System and apparatus comprising a multi-sensor catheter for right heart and pulmonary artery catheterization

Abstract

A system and apparatus comprising a multi-sensor catheter for right heart and pulmonary artery catheterization is disclosed. The multi-sensor catheter comprises multi-lumen catheter tubing into which at least three optical pressure sensors, and their respective optical fibers, are inserted. The three optical pressure sensors are arranged within a distal end portion of the catheter, spaced apart lengthwise within the distal end portion for measuring pressure concurrently at each sensor location. The sensor locations are configured for placement of at least one sensor in each of the right atrium, the right ventricle and the pulmonary artery, for concurrent measurement of pressure at each sensor location. The sensor arrangement may further comprise an optical thermo-dilution sensor, and another lumen is provided for fluid injection for thermo-dilution measurements. The catheter may comprise an inflatable balloon tip and a guidewire lumen, and preferably has an outside diameter of 6 French or less.

Claims

1. A multi-sensor catheter for direct measurement of blood pressure during cardiac catheterization comprising: a length of catheter tubing comprising a plurality of lumens extending between a proximal end and a distal end, and the distal end comprising a distal tip; a plurality of optical sensors and a plurality of optical fibers; a sensor end of each optical fiber being attached and optically coupled to an individual one of the plurality of optical sensors; the plurality of optical sensors and optical fibers being inserted into the plurality of lumens, the sensor ends of each optical fiber being spaced apart lengthwise to provide a sensor arrangement with said plurality of optical sensors positioned at respective sensor locations within a distal end portion of the catheter tubing; a proximal end of each of the plurality of optical fibers being coupled to an optical input/output connector at the proximal end of the multi-sensor catheter for connection to an optical control system; and the plurality of optical sensors of the sensor arrangement comprising at least two optical pressure sensors, with an aperture in the catheter tubing adjacent each optical pressure sensor for fluid contact; and wherein the sensor locations are configured to enable positioning of the at least two optical pressure sensors at positions within chambers of the heart, aorta and pulmonary artery comprising one of: a) right atrium and pulmonary artery; b) right atrium and right ventricle; c) left ventricle and left atrium; d) right atrium and left atrium; e) aorta and left ventricle; and f) right ventricle and pulmonary artery, to provide concurrent measurements of blood pressure waveforms by said at least two optical pressure sensors as positioned during cardiac catheterization.

2. The multi-sensor catheter of claim 1, having an outside diameter sized to allow insertion through a vein in an upper or lower arm.

3. The multi-sensor catheter of claim 1, comprising an inflatable balloon near the distal tip, the inflatable balloon being coupled by a balloon inflation lumen of the catheter tubing to a balloon inflation port at the proximal end of the catheter tubing.

4. The multi-sensor catheter of claim 1, further comprising a guidewire lumen.

5. The multi-sensor catheter of claim 1, further comprising: a guidewire lumen; an inflatable balloon near the distal tip, the inflatable balloon being coupled by a balloon inflation lumen of the catheter tubing to a balloon inflation port at the proximal end of the catheter tubing; and wherein the catheter tubing has an outside diameter sized to allow insertion into the heart through a vein in an upper or lower arm.

6. A multi-sensor catheter for direct monitoring of blood pressure at first and second locations during cardiac catheterization, comprising: a length of catheter tubing comprising first and second lumens extending between a proximal end and a distal end comprising an atraumatic distal tip; first and second optical pressure sensors and first and second optical fibers, a sensor end of each optical fiber being attached and optically coupled to an individual one of the optical pressure sensors; the first and second optical fibers being inserted respectively into the first and second lumens of the catheter tubing, the sensor ends of each optical fiber being spaced apart lengthwise to provide a sensor arrangement with said first and second optical pressure sensors positioned at respective first and second sensor locations within a distal end portion of the catheter tubing; a proximal end of each of the first and second optical fibers being coupled to an optical input/output connector at the proximal end of the catheter for connection to an optical control system; an aperture in the catheter tubing adjacent each optical pressure sensor for fluid contact; wherein said first and second sensor locations are spaced apart lengthwise to enable positioning of the first and second optical pressure sensors at first and second positions within one of: two chambers of the heart: a chamber of the heart and aorta; and a chamber of the heart and pulmonary artery; to provide concurrent blood pressure measurements by said first and second optical pressure sensors as positioned during cardiac catheterization.

7. The multi-sensor catheter of claim 6, wherein said first and second positions are one of: a) right atrium and pulmonary artery; b) right atrium and right ventricle; c) left ventricle and left atrium; d) right atrium and left atrium; e) aorta and left ventricle; and f) right ventricle and pulmonary artery.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings, identical or corresponding elements in the different Figures have the same reference numeral.

(2) FIG. 1 (Prior Art) shows a schematic longitudinal cross-sectional view of a known type of conventional PA catheter, which may be referred to as a Swan Ganz catheter;

(3) FIG. 2 (Prior Art) shows an enlarged transverse cross-sectional view of the PA catheter illustrated in FIG. 1 taken through plane A-A of FIG. 1 to show the lumens of the multi-lumen catheter tubing;

(4) FIG. 3 (Prior Art) shows schematic partial cross-sectional view of a human heart to illustrate placement of a conventional PA catheter within the right heart and the PA for measurement of pressure in the PA and for measurement of blood flow by thermo-dilution;

(5) FIG. 4 (Prior Art) shows schematic diagrams of a human heart to illustrate schematically placement of the conventional PA catheter within the right heart and PA for pressure measurements, at each the following positions: A. in the right atrium (RA); B. in the right ventricle (RV); C. in the pulmonary artery (PA); and D. in a pulmonary capillary wedge position (PCWP); the underlying plots show examples of a sequence of typical blood pressure waveform for each of positions A, B, C and D;

(6) FIG. 5 illustrates schematically a system according to a first embodiment, comprising an apparatus for right heart and PA catheterization comprising a multi-sensor PA catheter, which is optically coupled to a control unit;

(7) FIG. 6 shows a schematic longitudinal cross-sectional view of an apparatus for right heart and PA catheterization comprising a multi-sensor PA catheter according to the first embodiment of the present invention;

(8) FIG. 7 shows an enlarged axial cross-sectional view of the multi-lumen catheter illustrated in FIG. 6 taken through plane A-A of FIG. 6;

(9) FIG. 8 shows an enlarged axial cross-sectional view of the multi-lumen catheter illustrated in FIG. 6 taken through plane B-B of FIG. 6;

(10) FIG. 9 shows a schematic partial cross-sectional diagram of a human heart to illustrate placement of the multi-sensor PA catheter of the first embodiment within the right heart and PA for diagnostic measurements of hemodynamic parameters, including concurrent measurements of blood pressure in the RA, in the RV, in the PA and the PCWP;

(11) FIG. 10 shows a schematic longitudinal cross-sectional view of an apparatus for right heart and PA catheterization comprising a multi-sensor PA catheter according to the second embodiment of the present invention;

(12) FIG. 11 shows an enlarged axial cross-sectional view of the multi-lumen catheter illustrated in FIG. 10 taken through plane A-A of FIG. 10; and

(13) FIG. 12 shows an enlarged axial cross-sectional view of the multi-lumen catheter illustrated in FIG. 10 taken through plane B-B of FIG. 10.

(14) FIG. 13A illustrates schematically a graphical display of the control system showing three concurrent blood pressure waveforms from: A. sensor position P1 in the pulmonary artery (balloon deflated); B. sensor position P2 in the right ventricle; and C. sensor position P3 in the right atrium; together with selected numeric data comprising hemodynamic parameters derived from the pressure waveforms;

(15) FIG. 13B illustrates schematically a graphical display of the control system showing three concurrent blood pressure waveforms from: D. sensor position P1 in the pulmonary capillary wedge position with the balloon inflated; B. sensor position P2 in the right ventricle; and C. sensor position P3 in the right atrium; together with selected numeric data comprising hemodynamic parameters derived from the pressure waveforms; and

(16) FIG. 14 illustrates schematically a graphical display of the control system showing concurrent pressure waveforms from: A. sensor position P1 in the aorta and B. sensor position P2 in the right ventricle, with numeric data comprising hemodynamic parameters derived from the pressure waveforms, including an aortic regurgitation index (AR Index).

DETAILED DESCRIPTION OF EMBODIMENTS

(17) As illustrated schematically in the longitudinal cross-sectional view shown in FIG. 1, a conventional PA catheter 1000, which may be referred to as a Swan Ganz catheter, comprises a length of multi-lumen catheter tubing 1002 having at its distal end 1120 an inflatable balloon 1160. The catheter typically comprises a multi-lumen catheter tubing 1002, such as illustrated in FIG. 2, which is a cross-sectional view through plane A-A of FIG. 1. By way of example, the catheter tubing shown in FIG. 2 has four lumens 1004-1, 1004-2, 1004-3 and 1004-4, and an outside diameter of 5 French. Referring back to FIG. 1, there is a hub 1006 at the proximal end of the catheter with individual proximal ports 1010-1, 1010-2, 1010-3, and 1010-4. Ports 1010-1, 1010-2, 1010-3 are coupled by individual lengths of flexible tubing 1007 through the hub 1006 to respective lumens 1004-1, 1004-2 and 1004-3 of the catheter tubing 1002. Port 1010-4 is an electrical connector for a thermistor 20 which is located within the fourth lumen 1004-4 proximal to the balloon tip 1160, towards the distal end. Electrical connections for the thermistor 20 extend through lumen 1004-4 from the thermistor 20 to an electrical cable 1009 extending from the hub 1006. For simplicity of illustration of the longitudinal cross-sectional view shown in FIG. 1, the inner walls of the lumens are not shown.

(18) Traditionally, the multi-lumen catheter tubing 1002 of a Swan Ganz catheter is colored yellow and each of the ports 1010-1 to 1010-4 is color coded. A first lumen 1004-1 provides for inflating the balloon and has a corresponding proximal port 1010-1 for coupling to an air filled syringe for inflating and deflating the balloon. The balloon inflation port is conventionally colored red. The balloon 1160 typically has a volume of 0.5 ml to 1.5 ml and is connected to the balloon inflation lumen 1004-1. A second lumen 1004-2 is has an aperture 1012-2 opening at the distal tip 1120 and is connected at the proximal end to a proximal port 1010-2 (conventionally colored yellow) for connection to an externally placed pressure transducer, so that, when this lumen is filled with fluid, the blood pressure at the tip 1120 can be sensed. This port and lumen may also be used for sampling of blood at the tip of the catheter. For measurement of flow by thermo-dilution using the thermistor 20, there is third lumen 1004-3, which has a proximal injectate port (conventionally coloured blue) to allow for injection of a bolus of cold thermo-dilution fluid; this lumen has an injectate opening 1012-3 a distance of approximately 30 cm from the distal tip 1120. The fourth lumen 1004-4 accommodates the thermistor 20, i.e. an electrical temperature sensor, which is typically located at a distance of about 4 cm from the distal tip 1120; the electrical wires (not shown in FIG. 1) for the thermistor 20 extend through lumen 1004-4 to a proximal port 1010-4 (conventionally colored yellow) which comprises an electrical connector for the thermistor T. In this example, the second lumen 1004-2, which has an opening 1012-2 at the distal tip 1120 and respective proximal port 1010-2 has a larger diameter to allow for insertion of a guidewire, e.g. a standard 0.025 inch or 0.018 inch guidewire, to assist with introduction of the PA catheter into the right heart.

(19) FIG. 3 illustrates schematically a partial cross-sectional view of a human heart 500 with a PA catheter 1001 positioned within the right heart and left branch of the PA. The PA catheter 1001 is similar to that shown in FIGS. 1 and 2 comprising four lumens, i.e. one for balloon inflation, one for pressure sensing, one for the thermistor and one for fluid injection for measurement of flow by thermo-dilution. Similar to the catheter shown in FIG. 1, the four lumens are connected through a hub 1006 to proximal ports 1010-1, 1010-2, 1010-3 and 1010-4. The first lumen 1004-1 opens to the inflatable balloon 1160 and the first lumen is connected to the balloon inflation/deflation port 1010-1 for connection to an air filled syringe; the second lumen has an opening 1012-2 at the distal tip 1120 and a distal port 1010-2. The distal port 1010-2 that is used for the guidewire insertion can also be used either for connection to an external pressure transducer for measurement of blood pressure at the distal tip 1120, or, for blood sampling, such as for measuring mixed venous oxygen saturation (SvO.sub.2). The third port 1010-3 is the proximal injection port which is connected to the third lumen 1004-3 (FIG. 2) for fluid injection into the right atrium 521 through opening 1012-3. The fourth port 1010-4 comprises an electrical connector for the thermistor 20 which is located in the fourth lumen 1004-4 near the distal tip 1120.

(20) To position the PA catheter 1001 as illustrated schematically in FIG. 3, the catheter tip 1120 is introduced into the right atrium (RA) 521, e.g. in this example upwards through the inferior vena cava 520, and through the atrioventricular (tricuspid) valve 522 and into the right ventricle (RV) 523. During introduction, partial inflation of the balloon 1160 allows for blood flow directed insertion. That is, with partial inflation of the balloon 1160 in the right ventricle 523, the tip 1120 of the catheter tends to be drawn by the blood flow through the pulmonic valve 524 into the PA 525 and then from the PA towards the right or left branches 526L and 526R of the PA, and towards smaller pulmonary vessels which lead to the lungs. Pressure sensing at the tip is achieved by the fluid filled lumen 1004-2 which has opening 1012-2 at the distal tip 1120, and a proximal port 1010-2 which is connected to the externally placed pressure transducer for monitoring pressure at the catheter tip 1120. The port 1010-4 provides for electrical connections for the thermistor 20 (T), which located about 4 cm proximally from the balloon tip 1160, for measurement of blood flow by thermo-dilution. As illustrated schematically in FIG. 3, the opening 1012-3 of the fluid injection lumen is positioned to allow for injection of a bolus of cold fluid into the right atrium of the heart, for detection of a temperature change by the thermistor 20 (T) when the cold fluid reaches the PA 525 and its left and right branches 526L and 526R, to measure blood flow by a conventional thermo-dilution technique.

(21) In use of the PA catheter 1001, as illustrated in FIG. 4 (Prior Art), when the tip 1120 of the catheter 1001 is first introduced into the heart 500, e.g., through the superior vena cava as illustrated, and into the RA 521 (position A), a pressure measurement is made in the RA to assess the RA waveform. Then the tip of the catheter is advanced through the tricuspid valve 522 into the RV 523 (position B), and a pressure measurement is made within the RV to assess the RV waveform. The balloon is partially inflated so that the blood flow draws the balloon from the right ventricle 523, through the pulmonic valve 524 into the PA 525. When the tip of the catheter is in the PA (position C), the balloon is deflated, and another pressure measurement is made to assess the PA waveform. The tip of the catheter is then allowed to be drawn further into the PA and the balloon at the tip of the catheter is further inflated. When the inflated balloon wedges in a smaller branch 527 of the pulmonary vessels (position D) another pressure measurement is made, called the PA occlusion pressure, or pulmonary capillary “wedge” pressure (PCWP) waveform. PCWP provides an indirect measure of the left atrial pressure (LAP) and left ventricular end-diastolic pressure (LVEDP). As illustrated by the blood pressure waveform in the low part of FIG. 4, as the catheter tip is advanced, the observed waveform changes sequentially and show the transition from a RA pressure waveform, a RV pressure waveform, a PA pressure waveform and then a PCWP waveform. The cardiac output (CO), which is the amount of blood that the heart pumps per minute, may also be determined during a right-heart and PA catheterization. Pressure measurements may be made before and after administration of intravenous (IV) heart medications. The catheter may need to be repositioned several times to allow for several pressure measurements to be made at each of the different locations A, B, C and D within the heart and PA.

(22) Limitations of conventional PA catheters of this type include: Pressure measurements are made by a fluid filled pressure sensing catheter Pressure is transmitted through fluid filled lumen to a remote pressure transducer; pressure measurements are not always accurate. Pressure is measured at the distal tip only, so pressure can be measured only at one point or location at a time. Pressure measurements are sensitive to relative positioning and re-positioning of the catheter and pressure transducer, e.g. raising or lowering it relative to the heart in order to set the zero pressure (0 cm H.sub.2O) on the transducer. Kinking or bending of the catheter may dampen the characteristic waveforms seen at each position; There is time lag (and hysteresis) between pressure being applied to the opening at the tip of the pressure sensing lumen and transmission of pressure through the fluid filled lumen to the remote transducer. Pullback and repositioning of the catheter for multiple measurements may cause cardiac arrhythmias.

(23) A system and apparatus comprising a multi-sensor catheter for use in cardiology, which may include diagnostic measurements of cardiovascular parameters during right heart and PA catheterization, according to an embodiment of the present invention will be illustrated and described, by way of example, with reference to a system 2000 comprising a multi-sensor PA catheter 2001, illustrated schematically in FIGS. 5 to 9.

(24) Firstly, referring to FIG. 5, this schematic diagram represents the system 2000 comprising an apparatus 2001 comprising a multi-sensor catheter for right heart and PA catheterization procedures, coupled to a control system 2150, which comprises a control unit 2151 and user interface, such as the illustrated touch screen display 2152. The multi-sensor catheter 2001 comprises some components of a conventional PA catheter, including multi-lumen catheter tubing 2002. In the multi-sensor catheter of this embodiment, the catheter tubing comprises seven lumens 2004-1 to 2004-7, as illustrated in the transverse cross-sectional view in FIG. 7, which is a cross-section through A-A of FIGS. 5, 6 and 9. Typically, the catheter tubing 2002 has an outside diameter in the range of about 3-8 French (see Table 1 below for equivalent dimensions in mm and inches), and extends to an atraumatic flexible tip 2120 comprising an inflatable balloon 2160, as shown schematically in FIGS. 5 and 6.

(25) TABLE-US-00001 TABLE 1 French Diameter Diameter (Gauge) (mm) (inches) 2 0.667 0.027 3 1.000 0.039 4 1.333 0.053 5 1.667 0.066 6 2.000 0.079 7 2.333 0.092 8 2.667 0.105

(26) By way of example, the catheter tubing may typically be about 110 cm in length from the distal tip 2120 to the proximal end, which comprises a connection hub 2006. This length is suitable for introduction of the catheter into the right heart and PA through the superior vena cava (e.g. reached through the subclavian vein or interior jugular vein in the neck, or through the median cubital vein in the arm) or the inferior vena cava (e.g. reached through a femoral vein). For some applications, the catheter length may be shorter, e.g. 60 cm, or longer than 110 cm.

(27) The PA catheter 2001 differs from a conventional PA catheter, in that, internally, as illustrated schematically in the longitudinal cross-sectional view in FIG. 6, it also contains a multi-sensor arrangement comprising a plurality of optical pressure sensors 10 and an optical temperature sensor 20, and respective optical fibers 2011. The optical sensors 10 and 20 are not externally visible in FIG. 5, so the sensor positions are indicated schematically by P1, P2, P3 for the optical pressure sensors and T for the optical temperature sensor. The sensor positions P1, P2, P3 and T are located along a length L distal end portion 2130, near the distal tip 2120. As illustrated schematically in FIG. 5, the connection hub 2006 provides connection ports 2010-n, where n=1 . . . 7, for each of the seven lumens. Four of the connection ports, 2010-2, 2010-3, 2010-4, 2010-5 are optical connectors which are coupled via flexible optical connections 2008 through the hub 2006 to the optical fibers and sensors within their respective lumens, i.e. lumens 2004-2, 2004-3, 2004-4, 2004-5 shown in the transverse cross section in FIG. 7. The optical connectors each for the four optical sensors (P1, P2, P3 and T) plug into corresponding optical ports 2153 of the optical controller 2151 shown in FIG. 5.

(28) Referring to the schematic longitudinal cross-sectional view shown in FIG. 6, and the transverse cross-sectional view shown in FIG. 7, for simplification of illustration, the internal walls of the lumens 2004-1 to 2004-7 are omitted from FIG. 6 and only the optical fibers 2011 and sensors 10 and 20 are shown within the catheter tubing; elements shown in FIG. 6 are not drawn to scale. Thus, in description of FIG. 6, references to the lumens 2004-1 to 2004-7 are made based on FIG. 7. Also, by way of example, FIG. 7 shows typical dimensions for catheter tubing comprising seven lumens and having an outside diameter of 6 French (0.079 inch/2.00 mm), and for optical fibers 2011 having a diameter of 0.155 mm.

(29) As is conventional, the PA catheter 2001 has an inflatable balloon 2160 connected to a balloon inflation lumen 2004-1 which is coupled through the hub 2006 and flexible tubing 2007, to a balloon inflation/deflation port 2010-1. Another lumen 2004-6 provides for fluid injection or infusion through a fluid injection/infusion port 2010-6 for injection of fluid through an aperture 2012-6 located close to the sensor location P3. A central lumen 2004-7, which has an opening 2012-7 at the distal tip 2120, has an internal diameter which is sized to receive a standard guidewire, such as a 0.025 inch guidewire, to allow for over-the-guidewire directed insertion of the PA catheter. Thus, of the seven ports 2010-n (n=1 to 7), four of those ports 2010-2, 2010-3, 2010-4, 2010-5 comprise standard optical fiber connectors and the other three ports 2010-1, 2010-6 and 2010-7 are standard ports, such as luer fittings, i.e. for attachment of an air filled syringe for balloon inflation/deflation, for fluid injection or for guidewire insertion.

(30) The positioning of the optical sensors 10, 20 within the catheter tubing 2002 is illustrated in more detail in the schematic longitudinal cross-sectional view shown in FIG. 6. There are three optical sensors 10, at sensor locations P1, P2 and P3, for measuring pressure and one optical sensor 20, at sensor location T, for measuring temperature. Each optical sensor 10 and 20 is optically coupled to a respective individual optical fiber 2011. That is, each optical sensor is integral with a sensor end of the fiber, or is bonded to the optical fiber, to provide an optical coupling of the sensor and fiber. Each optical fiber, carrying its sensor at the end, extends through its own individual lumen 2004-2, 2004-3, 2004-4, 2004-5 of the multi-lumen catheter, as illustrated in the transverse cross-sectional view in FIGS. 7 and 8, which are taken through plane A-A and B-B, respectively, of FIG. 6. The central lumen 2004-7 is sized to accept a guidewire, such as a standard 0.025 inch guidewire to facilitate insertion of the catheter. The other six lumens are arranged symmetrically around the central lumen. A first lumen 2004-1 and its port 2010-1 provides for balloon inflation, as is conventional, with a distal opening (2012-1 not visible) coupled to the balloon. The proximal port 2010-1 is coupled via the hub 2006 to lumen 2004-1 via a length of flexible tubing 2007, and the port 2010-1 is typically a luer type fitting for connection to an air filled syringe (2100 in FIG. 5) for inflation and deflation of the balloon 2160. Second, third and fourth lumens, i.e. lumens 2004-2, 2004-3, 2004-4, each accommodate one of the optical pressure sensors 10 and its optical fiber 2011. Each of these lumens have a respective distal aperture 2012-2, 2012-3, 2012-4, adjacent to the respective sensor locations P1, P2, P3 for fluid contact. A fifth lumen 2004-5 accommodates the optical temperature sensor 20 and its optical fiber 2011. At the proximal end, the optical fibers 2011 for each sensor extend through a length of flexible tubing 2008 from the hub 2006 to the respective optical connector 2010-2, 2010-3, 2010-4, 2010-5. Thus the fibers are protected within the flexible tubing 2008 to provide a flexible optical connection of a desired length for connection to the control system. The sixth lumen, 2004-6 is provided for fluid injection of a bolus of cold fluid, to allow for flow to be determined by thermo-dilution by detection of temperature changes by optical temperature sensor 20. This fluid injection lumen 2004-6 has a distal opening 2012-6 positioned for delivering fluid to the right atrium, i.e. approximately 30 cm from the distal tip 2120, close to the sensor position P3. When the sixth lumen is not being used for injectate for thermo-dilution measurements, it may alternatively be used for fluid infusion or injection for other purposes. As mentioned above, the central or seventh lumen 2004-7 is provided for a guidewire, if guidewire assisted insertion is required. After withdrawal of the guidewire, optionally this lumen may be used for other purposes, such as blood sampling at the tip of the PA catheter, e.g. for mixed venous oxygen saturation (SvO.sub.2) measurements, or for measurement of cardiac output by the method of Fick.

(31) As illustrated schematically in FIG. 6, the three optical pressure sensors 10 at sensor positions P1, P2, P3, and the optical temperature sensor 20 at position T, are provided along a length of the distal end portion 2130 spaced by distances L.sub.1, L.sub.2 and L.sub.3 from sensor position P1. P1 is located at or close to the distal tip 2120, distal to the balloon 2160. P2 and P3 are arranged spaced apart lengthwise so that, in use, they can be located, respectively in the RV and the RA, when P1 is positioned in the PA. In use, corresponding apertures 2012-2, 2012-3, 2012-4 near each optical pressure sensor 10 allow for fluid contact with the optical pressure sensors. By way of example, P2 is located at a distance L.sub.2 from P1, typically L.sub.2 is about 20 cm; and P3 is located at a distance L.sub.3 from P1, typically L.sub.3 is about 30 cm. That is, the distance between P1 and P2, is about 20 cm and the distance between P2 and P3, is about 10 cm. The location of the optical temperature sensor T is proximal to the balloon and at a distance L.sub.1 from P1, where L.sub.1 is approximately 4 cm, so that the temperature sensor T is located in the PA when the pressure sensors locations P1, P2 and P3 are positioned, respectively, in the PA, the RV and the RA.

(32) The transverse cross-sectional view shown in FIG. 7 through plane A-A of FIG. 6, illustrates the arrangement of the seven lumens of the catheter tubing of the catheter 2001 of this embodiment. There is a central lumen 2004-7 for a guidewire, e.g. of a suitable diameter to receive a standard 0.025 inch guidewire. As mentioned above, the central lumen may also be used for fluid injection or infusion, or for blood sampling. The other six lumens 2004-1 to 2004-6 are arranged symmetrically around the central guidewire lumen 2004-7. As mentioned above, three of the lumens accommodate the three pressure sensors 10 at locations P1, P2 and P3 and their optical fibers 2011. One of the lumens accommodates the temperature sensor 20 at location T and its optical fiber 2011. One lumen, for example 2004-1, is provided for balloon inflation. The other lumen, for example 2004-6, is provided for fluid injection or infusion. Thus, as shown schematically in the cross-sectional view in FIG. 8, through B-B of FIG. 6, an aperture or orifice 2012-4 is provided adjacent sensor P3 for fluid contact. Correspondingly, as shown in longitudinal cross-sectional view in FIG. 6, an aperture is also provided near each of the other pressure sensors 10 for fluid contact The lumen for fluid injection has an opening 2012-6 that is located proximal to the aperture 2012-4 for P3 by a short distance, e.g. by 1 cm, or a distance L.sub.4, of about 31 cm from P1 at the distal tip 2120. The spacings of the three pressure sensors 10 are selected to allow sensor locations P2 to be placed in the RV and sensor location P3 to be placed in the RA when sensor P1 is in the PA, and so that the temperature sensor location T is positioned in the PA for measurement of blood flow in the PA by thermo-dilution.

(33) Referring back to FIG. 5, the proximal part of the apparatus 2001 provides for optical coupling of the proximal end 2102 to the control unit 2151. Four of the proximal ports 2010-2, 2010-3, 2010-4 and 2010-5, for the four optical sensors (P1, P2, P3 and T), comprise a standard type of optical fiber connector, each of which connects to a corresponding optical input/output connector 2153 of the control unit 2151. The control unit 2151 houses a control system comprising a controller with appropriate functionality, e.g. including a processor, data storage, and optical source and optical detector, and it provides a user interface, e.g. a keypad 2154, and touch screen display 2152, suitable for tactile user input, and for graphical display of sensor data. The user interface connection 2155 (e.g. a standard USB cable, or alternatively, a wireless connection) is used to transfer data between the control unit 2151 to the touch screen display 2152. The control unit 2151 and touch screen display 2152 may optionally be integrated within a single housing or module. As illustrated schematically in FIG. 5, each of the optical sensors is connected by an individual optical connector to the control unit. Alternatively, in other embodiments, the proximal ends of the optical fibers for each of the optical sensors may be bundled together and coupled into a single multi-fiber proximal optical connector for connection to a multi-fiber optical port of the control unit. At the proximal end 2102 of apparatus 2001, a hub 2006 couples each lumen of the catheter via a respective length of flexible tubing to an individual proximal port. The other three ports, 2010-1, 2010-6 and 2010-7 comprise standard connections, such as Luer fittings, for attachment of a syringe or tubing. When not in use, the latter ports would typically be supplied with sterile plugs. In use, port 2010-1 is connected to a small air filled syringe 2100 for inflation/deflation of the balloon tip 2160. Port 2010-6 is used for fluid injection or infusion. Port 2010-7 is sized to accept a guidewire 2200, e.g. a standard 0.025 inch guidewire, or this port can be used for blood sampling at the tip of the catheter.

(34) The optical pressure sensors 10 (P1, P2, P3) are preferably Fabry-Perot (FP) Micro-Opto-Mechanical System (MOMS) sensors, such as described by FISO Technologies (E. Pinet, “Pressure measurement with fiber-optic sensors: Commercial technologies and applications” 21st International Conference on Optical Fiber Sensors, edited by Wojtek J. Bock, Jacques Albert, Xiaoyi Bao, Proc. of SPIE Vol. 7753, (2011)). These optical pressure sensors comprise an optical fiber having a FP MOMS sensor at the sensor end of the fiber for sensing pressure. By way of example, for standard diameter optical fibers, each fiber (e.g., fibers 2011 in FIGS. 7 and 8) has a diameter of 0.155 mm (0.006 inch) and each optical pressure sensor (e.g., sensors 10 in FIG. 8) has a diameter of 0.260 mm (0.010 inch).

(35) For measurement of flow by thermo-dilution, the optical temperature sensor 20 (T) may, for example, be a GaAs (Gallium Arsenide) fiber optic temperature sensor, as described by FISO technologies (E. Pinet et al., “Temperature fiber-optic point sensors: Commercial technologies and industrial applications”, MIDEM Conference Proceedings, Sep. 29-Oct. 1, 2010, Radenci, Slovenia).

(36) A typical material for fabrication of the multi-lumen catheter is a flexible polymer, such as, 4033 Pebax® (a Polyether block amide or PEBA, or other suitable thermoplastic elastomer (TPE)), which has regulatory approval for fabrication of conventional PA catheters. The wall thickness of the tubing may be ˜0.005 inch. The guidewire lumen has a diameter, for example, of 0.029 inch to accommodate a standard 0.025 inch guidewire. Conventional coloring of the standard ports may be provided. A different color coding may be provided for the optical ports to facilitate quick recognition and connection to correspondingly color coded ports of the optical controller. As illustrated schematically the transverse cross-sectional views in FIGS. 7 and 8, sensors and fibers of these dimensions can be accommodated within catheter tubing 2002 having an outside diameter of 6 French (0.079 inch or 2.0 mm—see Table 1).

(37) For some applications a larger diameter catheter, e.g. 7 French, may be acceptable.

(38) For smaller fibers, e.g. 0.100 mm fibers, and smaller diameter sensors, if a guidewire lumen is not required, or if the guidewire to be used is smaller than 0.025 inch, e.g. 0.018 inch, the dimensions of the lumens and the outside diameter of the catheter tubing may be reduced in size accordingly, e.g. to 5 French or less.

(39) It is preferable that the arrangement of the lumens has rotational symmetry about the longitudinal axis, and the wall thickness of each lumen is selected to provide the required mechanical characteristics, such as an appropriate degree of flexibility and stiffness, with symmetric torque characteristics along its length. For over the guidewire insertion, a more flexible catheter may be selected. For insertion without a guidewire, a stiffer catheter may be desirable. For example, while the catheter requires sufficient flexibility to traverse from the RA into the RV and then be guided into the PA, it is also desirable that the catheter has sufficient stiffness or rigidity (i.e. is not too floppy) to withstand turbulent blood flow within the ventricles, to withstand distortion or kinking, and to maintain a minimum bend radius of the optical fibers.

(40) When the optical pressure sensors are FP MOMs sensors, they measure pressure at point locations of the sensor at the end of the fiber, i.e. pressure exerted on the FP membrane, and optical measurements are based on interference measurements, i.e. frequency shifts, rather than amplitude measurements. Blood pressure measurements are made with greater accuracy and reliability compared to conventional pressure sensing with a fluid filled catheter and an external pressure transducer. FP MOMS sensors can provide significantly more accurate pressure measurements, with minimal drift, compared to electrical pressure sensors, such as piezo-electric sensors. Optical pressure sensors avoid the need for multiple long thin electrical connections, which not only have significant electrical drift, but are subject to cross-talk and electro-magnetic interference. For similar reasons, it is also preferable that for measurement of flow by thermo-dilution or thermo-convection, the temperature sensor is preferably also an optical sensor rather than an electrical sensor. For example, for thermo-dilution measurements, the temperature sensor may be a fiber optic sensor which measures temperature based on the temperature dependence of a GaAs sensor at the tip of the fiber, i.e. a temperature dependent shift in the peak wavelength of light reflected from the sensor.

(41) FIG. 9 provides a schematic diagram of the heart 500 to illustrate placement of the multi-sensor catheter 2001 of the first embodiment during a right heart and PA catheterization procedure to measure pressure concurrently in the right atrium 521, right ventricle 523 and PA 525. In this example, the multi-sensor catheter 2001 is introduced into the heart through the inferior vena cava 520, through the right atrium 521, through the tricuspid valve 522 into the right ventricle 523, through the pulmonic valve 524 and into the PA 525. The tip 2120 of the catheter extends into the left branch 526L of the PA. The aperture 2012-2 for pressure sensor P1, which is distal to the balloon 2160 is located in the left branch of the PA 526L. The temperature sensor T is also in the left branch of the PA 526L, proximal to the balloon. Aperture 2012-3 for pressure sensor P2 is located in the right ventricle 523. Aperture 2012-4 for pressure sensor P3 is located in the right atrium 521. The proximal fluid injection port 2012-6 is also located in the right atrium 521. Thus, when the optical connectors for the three optical pressure sensors P1, P2 and P3, and the optical temperature sensor T are connected to the optical control system, the pressure measurements in the RA, RV and PA can be made concurrently. Also, the optical temperature sensor T can be used for measurement of flow by a conventional thermo-dilution technique.

(42) For some applications, a temperature sensor for measurement of flow by thermo-dilution may not be required, and it may be omitted.

(43) A multi-sensor PA catheter 3001 of a second embodiment is illustrated in FIGS. 10, 11 and 12. As shown in a longitudinal cross-sectional view of FIG. 10, in this embodiment, the multi-sensor catheter comprises three optical pressure sensors 10, at sensor locations similar to those of the multi-sensor PA catheter 2001 of the first embodiment, but there is no temperature sensor. As illustrated in the transverse cross-sectional views in FIGS. 11 and 12, in this simplified version of the multi-sensor PA catheter, the catheter tubing 3002 comprises five lumens, i.e. a first lumen 3004-1 for balloon inflation; three lumens 3004-2, 3004-3, 3004-4, one for each of the three pressure sensors 10 and its respective optical fiber 3011; and the central lumen 3004-7 is provided for a guidewire, and/or for blood sampling, as described for the multi-sensor PA catheter of the first embodiment. As shown in FIG. 10, the optical fibers 3011 for the optical pressure sensors 10 are connected from the respective lumens, through connection hub 3006, and via flexible tubing 3008 to respective ports 3010-2, 3010-3 and 3010-4. Ports 3010-2, 3010-3, 3010-4 comprise optical connectors for the three optical pressure sensors 10 in the second, third and fourth lumens. Each of the three lumens 3004-2, 3004-3, 3004-4 has a respective aperture 3012-2, 3012-3 and 3012-4 for fluid contact with the respective optical pressure sensors 10. Port 3010-1 connects via tubing 3007 to the hub 3006 and the first lumen for inflation/deflation of the balloon 3160. Port 3010-7 connects via tubing 3007 to the central lumen which has an opening 3012-7 at the distal tip 3120 for a guidewire, or for blood sampling at the tip of the catheter. Radiopaque markers 3014 are provided along the length of the catheter tubing to assist in positioning the sensors 10 within the heart. As illustrated, by way of example, in FIGS. 11 and 12, the catheter tubing has an external diameter of 6 French, and provides a central lumen 3004-7 having an inside diameter which can accept a guidewire, e.g. a standard 0.025 inch guidewire, and four lumens arranged symmetrically around the central lumen. That is, one lumen for balloon inflation, and three lumens for three optical fibers of 0.155 mm diameter and FP-MOMS optical pressure sensors of 0.260 mm diameter. The outside diameter of the PA catheter tubing may be reduced if smaller diameter optical fibers and sensors are used, or for use with a smaller diameter guidewire.

(44) In comparing the multi-sensor catheters of the first and second embodiments, comprising 7 lumens and 5 lumens respectively, it will be appreciated that the dimensions of each catheters, such as the external diameter, the number of lumens and the thicknesses of the internal walls of the catheter defining each lumen are described by way of example only. As mentioned above, smaller optical sensors and smaller optical fibers may be accommodated within smaller lumens, to provide a catheter having a smaller outside diameter. This may be desirable for some applications. The material from which the catheter is made, and the wall thicknesses defining the lumens, may be selected to provide the catheter with a required stiffness or flexibility, and size.

(45) In other alternative embodiments, when the catheter is to be flow directed by the balloon tip, and introduction over a guidewire is not required, the guidewire lumen may be omitted.

(46) For some applications, for example for pediatric or neonatal use, a significantly smaller diameter catheter may be required, e.g. 3 French. Correspondingly, the spacings of the optical pressure sensors would be closer together, i.e. matched to the smaller dimensions of the chambers of patient's heart, for placement of one sensor in the RA, one in the RV and one in the PA. In such a case the guidewire lumen may be omitted so that three pressure sensors can be accommodated within a multi-lumen catheter of the required diameter. While three pressure sensors are desirable for concurrent measurements of RA, RV and PA pressure waveforms, when a guidewire lumen is required for a smaller diameter catheter, it may only be possible to accommodate two optical pressure sensors. In this arrangement, the two sensors would be spaced apart so that initially, one sensor can be positioned in the RA and one in the RV for concurrent measurement of RA and RV pressure waveforms, and then subsequently the catheter would be advanced to position one sensor in the RV and one in the PA for concurrent measurement of RV and PA pressure waveforms, and for RV and PCWP pressure waveforms.

(47) The lengthwise spacings (L.sub.2 and L.sub.3) of the optical pressure sensors at locations P1, P2 and P3 described with respect to the multi-sensor catheters of the first and second embodiments, i.e. for measurement of pressure waveforms concurrently in the RA, RV and PA refer to typical spacings required for an adult human heart, where the distance from the RA to the RV is about 10 cm and the distance from the RV to the PA, in a region downstream of the pulmonic valve, is about 10 cm. The PCWP position is typically a further 10 cm into one of the right or left branches of the pulmonary artery, i.e. about 20 cm from the RV. Thus, to position P1 in the PA near the wedge position, P2 in the RV, and P3 in the RA, L.sub.2 is about 20 cm and L.sub.3 is about 30 cm. The location of the temperature sensor T is typically positioned between P1 and P2, spaced a distance L.sub.1 from P1, for measurement of blood flow within the PA, where L.sub.1 is e.g. about 4 cm to 10 cm. For pediatric and neonatal use, i.e. for smaller sized hearts, the spacings of the sensors would be reduced accordingly.

(48) While it is envisaged that multi-sensor catheters for right heart and PA catheterization may comprise more than three optical pressure sensors, there is a practical limit to how many sensors can be accommodated within a multi-lumen catheter of a particular outside diameter.

(49) Since multi-sensor PA catheters are intended as disposable, single use catheters, in practice, the number of optical sensors may also be limited by component costs and fabrication costs. Currently, standard diameter optical fibers and optical pressure sensors are lower cost than smaller diameter optical fibers and optical pressure sensors. Since each pressure sensor is in an individual lumen of the multi-lumen catheter, the available space for each lumen is also limited by the wall thickness and tolerances for each lumen of a multi-lumen catheter. As described herein, it is currently feasible to manufacture a multi-sensor PA catheter with three optical pressure sensors and one optical temperature sensor, within a 6 French multi-lumen catheter. Use of smaller fibers and sensors or smaller guidewire may allow the diameter to be reduced to 5 French or less.

(50) In a multi-sensor catheter of yet another embodiment, instead of three optical pressures sensors and one optical temperature sensor, it may be desirable to have four optical pressure sensors to enable concurrent pressure measurements in the right atrium, in the right ventricle, in the PA near the pulmonic valve and also in a branch of PA for measurement of the PCWP.

(51) For example, if a temperature sensor is not required for blood flow measurements, for example where blood flow is measured by an alternative technique, e.g. by the Fick method, a fourth optical pressure sensor may be provided instead of the optical temperature sensor, so that the multi-sensor catheter can be introduced so as to position one sensor in the RA, one sensor in the RV, one sensor in the PA, and one sensor for measuring PCWP when the balloon is inflated. By way of example, in such an arrangement, four pressure sensors P1, P2, P3 and P4 are spaced at intervals of ˜10 cm, i.e. the distance P1 to P2 (L.sub.1) is 10 cm, P1 to P3 (L.sub.2) is 20 cm, and P1 to P4 (L.sub.3) is 30 cm.

(52) This arrangement may be desirable for longer term monitoring of pressure waveforms in the RA, RV, PA, as well PCWP pressure waveforms. That is the catheter may be positioned in a fixed and stable location, to enable observation of pressure waveforms at each sensor location over an extended time period, e.g. for ICU patients requiring monitoring over several days or more.

(53) Alternatively, where it is not feasible to accommodate an optical temperature sensor as well as the desired number of optical pressure sensors, or for cost reasons, a conventional small sized, low cost, electrical flow sensor, i.e. a thermistor, may be used, with conventional electrical connections to the control system.

(54) In the embodiments described above, radiopaque markers may be provided near the balloon, and optionally near each sensor, to assist in locating the tip and positioning the sensors in use, i.e. using conventional radio-imaging techniques, when introducing the guidewire and positioning the pressure sensors in the right atrium, right ventricle and PA. The radiopaque markers typically comprise a suitable heavy metal e.g. barium, tantalum, gold or platinum. Alternatively, markers are provided at regular intervals, e.g. at 10 cm intervals along the length of the catheter tubing as is conventional for PA catheters.

(55) Preferably that the optical fibers have some freedom to move or slide within the lumen when the catheter is flexed. The fibers are of the appropriate length so that the sensors at the sensor end (distal end) of the fibers are appropriately positioned at sensor locations in the distal end portion of the catheter. Each of fibers may be secured near the proximal end, e.g. by adhesive bonding where they pass through the hub. Each fiber may also be secured in its lumen, near the sensor location, e.g. by injection of a medical grade adhesive through the wall of the lumen.

(56) If required, in use, the lumens containing the fibers and sensors may be flushed with fluid, e.g. saline solution, to remove air from the catheter lumens. Alternatively, an adhesive, or a medical grade gel, may serve to plug the lumen each side of the aperture surrounding the optical sensor, while leaving the sensor exposed for fluid contact. For example, a bolus of medical grade adhesive may be injected through the tubing to secure the fiber near each sensor and to plug the lumen around the fiber. Similarly, the adhesive may also be injected into the lumen distal to the aperture. Also, if required, components of the multi-sensor catheter may be coated to reduce blood clotting, for example, if the multi-sensor catheter is to be left in place for an extended period.

(57) The optical pressure sensors 10 at locations P1, P2, P3 are preferably Fabry-Perot Micro-Opto-Mechanical-Systems (FP MOMS) pressure sensors. As an example, a suitable commercially available FP MOMS pressure sensor is the Fiso FOP-M260. These FP MOMS sensors meet specifications for an appropriate pressure range and sensitivity for blood pressure measurements. They have an outside diameter of 0.260 mm (260 μm). Typically, they would be attached and optically coupled (i.e. integral with or bonded to) to a sensor end of an optical fiber with an outside diameter of 0.100 mm (100 μm) to 0.155 mm (155 μm). Optical fibers and FP MOMS sensors of smaller diameter tend to be more expensive, and may be used, when appropriate.

(58) The optional optical flow sensor 20 may comprise an optical thermo-dilution or an optical thermo-convection flow sensor, e.g. as described in U.S. patent application Ser. No. 14/354,588.

(59) For operation of the optical sensors, the optical output ports 2010-2, 2010-3, 2010-4, 2012-5 couple to the respective optical ports of the control unit 2151 (e.g. see FIG. 5) for controlling operation of the optical sensors 10 and 20. The flexible tubing 2008 surrounding each of the optical fibers extends between the hub 2006 and the optical connector of the control unit to provide a flexible optical coupling from the hub 2006 to the control unit 2151. This tubing is provided to protect the optical fibers and can have any appropriate diameter and flexibility. Since the catheter is intended for single use only, preferably the optical connectors are standard low cost optical connectors. Similarly, the flexible tubing, and other connectors for the other ports are preferably standard materials and components, such as luer fittings or other medical standard fluid ports and electrical connectors, as appropriate, which can be sterilized, and so that the multi-sensor catheters can be provided in single-use sterile packaging, using conventional standard processes for medical devices.

(60) For protection of the sensors during assembly, it may be preferred to insert optical fibers and optical sensors through the respective lumen from the distal end of the catheter and subsequently form the optical connector at the proximal end, and then close the lumen at the distal tip. On the other hand, when the optical connector is pre-formed at the proximal end of the sub-assembly before insertion, the sensor end of the sub-assembly is inserted into the catheter from proximal end of the respective lumen. In either case, it is preferable that the catheter lumens have smooth rounded surfaces, with non-stick internal surfaces, i.e. to avoid sharp edges, so that the sensors and optical fibers can slide smoothly into their catheter lumen without catching on sharp edges or corners, to avoid mechanical damage to the sensors or optical fibers. However, in use of the multi-sensor catheter, it is preferable that the fibers are fixed at the proximal end only of the catheter tubing so that the fibers have some freedom to move or slide within the lumens when the catheter is flexed. If required, the optical fibers may also be adhesively bonded near the aperture to secure the sensor at the appropriate sensor location.

(61) As mentioned above, it is desirable that the multi-sensor PA catheter has mechanical characteristics, such as stiffness and flexibility, similar to a standard PA catheter. The optical fibers and optical sensors do not add significant stiffness to the catheter, and thus these characteristics are primarily determined by the type of material and wall thickness used for the multi-lumen catheter tubing.

(62) Other factors for consideration are: regulatory requirements for medical devices, ease of use and safety. For these reasons, it is desirable that the materials for fabrication of a multi-sensor PA catheter are based on a conventional tried and tested PA catheter or other medical device, i.e. based on a predicate device structure which has regulatory approval and which is fabricated with materials and components which already have FDA and/or CE mark regulatory approval.

(63) It will be appreciated that in alternative embodiments or variants of the multi-sensor catheters of the embodiments described in detail above, different combinations of one or more features disclosed herein, and features disclosed in the related patent applications referenced herein, may provide multi-sensor catheters of further alternative embodiments

(64) As disclosed herein, the cardiologist is offered multi-sensor catheters which have particular application for right heart and PA catheterization. These multi-sensor catheters are configured for monitoring and diagnostic measurements of hemodynamic parameters, including concurrent measurement of blood pressure within the RA, RV and PA.

(65) Control System and Graphical Display of Pressure Waveforms and Associated Hemodynamic Parameters.

(66) Referring to the control system, which was described above with reference to FIG. 5, and as described in the above referenced related patent applications, it will be apparent that the control system may be used with multi-sensor catheters and multi-sensor guidewires for concurrent blood pressure measurements at each pressure sensor location, using, two, three or more optical pressure sensors. Optionally, for flow measurements, the multi-sensor catheter or guidewire is further equipped with an optical or electrical flow sensor. The control system comprises a light source and detector and an optical interface for coupling, via respective input/output ports, to each of the optical fibers and optical sensors of the multi-sensor catheter or guidewire. The control system also comprises data storage and processing means configured for processing optical data indicative of pressure values and optionally, optical or electrical data indicative of flow velocity values. For use with multi-sensor catheters and multi-sensor guidewires, for example, the multi-sensor catheter disclosed herein having three optical pressure sensors, and an optional optical flow sensor, the control system would have a corresponding number of signal processing channels with optical inputs for each of the optical sensors. The signal processing elements for each channel may be referred to as a signal conditioning unit. For measuring blood pressure and flow within the heart and blood vessels, in particular for measuring intravascular or transvalvular blood pressure gradients, the processing means is further configured for graphically displaying pressure data, and optionally flow velocity data, comprising a plurality of blood pressure waveforms, i.e. a pressure waveform from each optical pressure sensor. The concurrent blood pressure waveforms for each of the optical sensors may be displayed for one or more time intervals, and during one or more cardiac cycles. Preferably, the processing means is further configured to derive hemodynamic parameters from the blood pressure data, and optionally from flow velocity data, and display numeric values of the parameters as well as display the pressure waveforms from each sensor. By way of example only, some schematic representations of pressure waveforms and associated numeric data, for a patient with a healthy or normally functioning heart, are shown in FIGS. 13A, 13B and 14. In practice, pressure waveforms and pressure values vary from patient to patient and may be dependent on a number of factors, such as, whether or not the patient has a healthy or diseased heart, or other conditions that may affect functioning of the heart. Skilled medical practitioners will recognize characteristic variations in each pressure waveform and associated pressure values, indicative of e.g. valvular stenosis or other patient physiology. Advantageously, in use of a multi-sensor catheter, concurrent pressure measurements from multiple optical pressure sensors enable the cardiologist to directly compare multiple pressure waveforms, in real-time, from the RA, RV and PA/PCWP.

(67) As an example, FIG. 13A represents a graphical display 2152-1 showing three blood pressure waveforms from a three sensor PA catheter: A. pressure sensor location P1 in the pulmonary artery; B. pressure sensor location P2 in the right ventricle; and C. pressure sensor location P3 in the right atrium. Pressure units are displayed in mmHg. Optionally, it may be desirable to select and display one or multiple pressure waveforms and related parameters in different formats. For example, during right heart and pulmonary artery catheterization with a multi-sensor catheter as disclosed herein, in addition to displaying concurrent blood pressure waveforms from each the right atrium, right ventricle and pulmonary artery, a plurality of numeric values, such as, peak pressures, mean pressures, peak-to-peak (PK-PK) pressure differentials for each curve, and pressure differentials or gradients between the right atrium and right ventricle, and between the right ventricle and pulmonary artery may be displayed in real time. For example, as illustrated schematically by the numeric data to the right of the graphical display shown in FIG. 13A, numeric data selected for display may include the mean pressure of the RA, systolic/diastolic pressure for RV/PA, a peak-to-peak gradient (PPG) for RV to PA, a PPG for RA to RV, and heart rate HR. As is conventional, the user interface may include a number of buttons or keys, such as shown at the bottom of the display in FIG. 13A, e.g. to select parameters for display, change display modes, and input identification. FIG. 13B represents a graphical display 2152-2 for three pressure waveforms, similar to that shown in FIG. 13A, except that waveform A for the PA pressure is replaced with waveform D for the pressure sensor location P1 is in the pulmonary capillary wedge position with the balloon inflated.

(68) Correspondingly, in use of a multi-sensor guidewire during TAVR, e.g. a multi-sensor guidewire with two optical pressure sensors to assess functioning of the aortic valve, before and after a TAVR procedure. As illustrated schematically in FIG. 14, the system comprises a graphical display 2052-3 which shows two pressure waveforms: A. from pressure sensor location P1 in the left ventricle and B. from pressure sensor location P2 in the aorta, together with numeric values derived from the pressure waveforms from the left ventricle and aorta, e.g. a transvalvular pressure gradient. For example, the system may automatically compute an aortic regurgitation index (ARi or AR Index) and display the ARi value in real time. The ARi may be computed from measured values of the left ventricular end-diastolic pressure (LVEDP), diastolic blood pressure (DBP), and systolic blood pressure (SBP), as illustrated in FIG. 14. and is defined as:
ARi=((DBP−LVEDP)/SBP)×100

(69) In one embodiment, the control system comprises a signal processing unit for receiving optical data and optionally electrical data, from a multi-sensor catheter or guidewire. The signal processing unit is coupled by a data connection to a general purpose computer system, which may be personal computer (PC), such as a laptop or tablet PC, comprising processing means, i.e. one or more processors and a computer program product, embodied in a non-transitory computer readable medium storing instructions, in the form of code, for execution by the processing means. The computer program product is, for example, a software application comprising instructions for execution in a processor of the tablet PC for receiving or retrieving data, and displaying a plurality of concurrent pressure waveforms from the optical pressure sensors, and for computing, and displaying in real-time, associated hemodynamic parameters or an index, such as ARi.

(70) In another example of a TVT procedure, a multi-sensor guidewire or catheter may be used for measurement of concurrent pressure waveforms upstream and downstream of the mitral valve, e.g. to assess functioning of the mitral valve before and after TMVI.

(71) For example, the tablet PC is configured for graphically displaying pressure data, and optionally flow velocity data, e.g. comprising a plurality of blood pressure waveforms. The concurrent blood pressure waveforms for each optical sensor may be displayed for one or more time intervals, and during one or more cardiac cycles. The processing means is further configured to derive and display hemodynamic parameters from the blood pressure data and flow velocity data. For example, during right heart and pulmonary artery catheterization with a multi-sensor catheter as disclosed herein, in addition to displaying blood pressure waveforms from the right atrium, right ventricle and pulmonary artery, a selected plurality of numeric values such as peak pressures, mean pressures, peak to peak pressure differentials for each curve, and pressure differentials or gradients between the right atrium and right ventricle, and between the right ventricle and pulmonary artery can be displayed in real time.

(72) As is conventional, the system may comprise a user interface, such as a keyboard or touchscreen, to allow the operator to select from available information which waveforms or parameters are to be displayed. The interface may allow the operator to input user data such as patient identification, and data interfaces may be provide to output data to other devices or systems, or receive data from other sources, such as from other sensors or monitoring systems, which are typically used in an ICU or OR. For example, in a cardiac catheterization laboratory, the control system for a multi-sensor catheter or guidewire may be coupled to, or part of, a computing system controlling other equipment, and which is equipped with one or more large screen displays close to the operating table, and other remote displays in a monitoring area. The latter are used to display various forms of data, sequentially, concurrently, or on demand. Such data may include, e.g. fluoroscopic imaging, with or without contrast media, and transesophageal echo-cardiography (TEE) images, as well as sensor data comprising pressure waveforms from the multi-sensor catheter or guidewire and associated hemodynamic parameters calculated or derived from the received optical pressure sensor data.

(73) While a specialized signal processing unit or interface, which may be referred to as a “signal conditioner”, is used to receive optical data from the multi-sensor catheter or multi-sensor guidewire, and generate output data indicative of pressure for display of pressure waveforms, the output data may be fed by a standard data connection, wired or wireless, to a processor, such as a general purpose computer, which is configured to provide the required functionality. For example, the system includes a processor and a computer program product (typically referred to as a software application or computer code), embodied in a non-transitory computer readable medium storing instructions, for execution in a processor of a control system for a multi-sensor catheter or a multi-sensor guidewire, for processing optical data received concurrently from a plurality of optical pressure sensors indicative of blood pressure, displaying a corresponding plurality of blood pressure waveforms, and optionally flow velocity data, and displaying numeric data relating to selected hemodynamic parameters and indexes.

(74) TABLE-US-00002 TABLE 2 Abbreviations or acronyms ARi or AR Index Aortic Regurgitation Index Cath Lab Cardiac Catheterization Laboratory CO Cardiac Output CVC Central Venous Pressure catheter DBP Diastolic Blood Pressure FP MOMS Sensor Fabry-Pérot Micro-Opto-Mechanical-System Sensor ICU Intensive Care Unit LAP Left Atrial Pressure LVEDP Left Ventricular End-Diastolic Pressure OR Operating Room PA Pulmonary Artery PCWP Pulmonary Capillary Wedge Position/Pressure PEBA PolyEther Block Amide RA Right Atrium RHC Right Heart Catheterization RV Right Ventricle SvO.sub.2 Mixed venous oxygen saturation SBP Systolic Blood Pressure TAVI or TAVR Transcatheter Aortic Valve Implantation or Replacement TMVI or TMVR Transcatheter Mitral Valve Implantation or Replacement TPE Thermoplastic elastomer TVR Transcatheter heart Valve Replacement TVT Transcatheter Valve Therapies (TVT).

INDUSTRIAL APPLICABILITY

(75) Multi-sensor PA catheters according to embodiments of the invention disclosed herein provide real-time, concurrent, multi-chamber (RA and RV) pressure measurements within the right heart and also the PA. Each pressure measurement is taken concurrently under identical and stable conditions, while the multi-sensor catheter is positioned to locate one sensor in each of the RA, RV and PA.

(76) In contrast, during RHC using a conventional PA catheter, it is necessary to move the catheter to get each pressure measurement, so each measurement is taken at a different time, under different conditions. For example, withdrawing a PA catheter from the PA to the RV may cause cardiac arrythmia or premature ventricular contraction (PVC). That is, the instantaneous condition for each pressure measurement is impacted by moving the catheter.

(77) In some instances, such as monitoring in an ICU, it may be too risky to move the PA catheter once the catheter tip is placed in the PA. For a conventional PA catheter, it would then only provide the PA pressure, not a RV and RA pressure. Thus, where appropriate, the multi-sensor catheter offers continuous real-time and concurrent monitoring of all of RA, RV and PA pressures for an extended time, e.g. over a period of days, for an ICU patient. In this scenario, RA pressure monitoring provides alternative to monitoring of central venous pressure (CVP).

(78) For post-operative monitoring, there may be risks in use of a Swan Ganz catheter, and there is a need to appropriately select patients who need Swan Ganz catheterization. For patients where Swan Ganz catheterization is appropriate, the multi-sensor PA catheter offers continuous real-time and concurrent monitoring of all of RA, RV and PA pressures.

(79) Since these pressure measurements also provide an indirect measure of left heart hemodynamic parameters, these measurements can help to identify pathology and physiological problems and select appropriate therapies, drugs, and procedures. For example, pressure measurements may help to differentiate patient physiologies, and identify a filling problem vs. a valve problem, such as, an obstruction of the tricuspid valve.

(80) For example, multiple concurrent blood pressure measurements during RHC may show, e.g., a high RA pressure and a low RV pressure, which may indicate tricuspid valve stenosis/obstruction. In conditions such as pulmonary edema, concurrent pressure measurements of the RA, RV, PA and PCWP may provide information which helps to determine or differentiate, e.g., whether is symptoms are caused by a RH or LH problem, a valve problem (stenosis or regurgitation), a muscle problem, cardiac restriction or constriction, PA hypertension, or a primary lung problem (such as Acute Respiratory Distress Syndrome).

(81) The number of TAVR procedures per year is projected to increase dramatically in the next few years. During left heart catheterization for TAVR, the Aortic Regurgitation index (ARi) is a widely used parameter for assessing function of the aortic valve before and after valve repair or replacement. It is also expected that the mitral valve replacement will increase in future years, but aortic valve replacement is much more common.

(82) By comparison, pulmonic valve interventions are rare and there is not a commonly used PA index. However, multi-sensor catheters providing concurrent pressure measurements in the RA, RV and PA may allow for an appropriate index to be adopted for RHC.

(83) Although embodiments of the invention have been described and illustrated in detail, it is to be clearly understood that the same is by way of illustration and example only and not to be taken by way of limitation, the scope of the present invention being limited only by the appended claims.