Abstract:
A method for mechanically assisting the pumping action of the heart. A catheter is provided comprising an elongate member having a proximal end, a distal region, an expandable member attached in the distal region, and an inflatable member in the distal region and attached distal the expandable member. The catheter is advanced into the aorta. The expandable member is expanded to at least partially obstruct the aorta. The inflatable member is inflated during diastole. The inflatable member is then deflated during the ejection phase of the left ventricle while expansion of the expandable member is maintained. The pumping action of the heart is thereby mechanically assisted. Cerebral perfusion augmentation may also be achieved by use of combined coarctation-counterpulsation devices and methods. Devices for practicing methods with increased volume-displacement efficiency are also described.

Description:
This is a divisional of U.S. application Ser. No. 10/654,368, filed Sep. 2, 2003, now abandoned which is hereby expressly incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to methods and devices for coarctation and counterpulsation for left ventricular assist and enhancement of cerebral blood flow. More particularly, the invention relates to catheters with propagating balloon inflation for intraaortic balloon pumping with increased volume-displacement efficiency. 
     BACKGROUND OF THE INVENTION 
     Despite recent advances made in diagnosing and treating cardiovascular disorders, coronary heart disease remains the leading cause of mortality in the United States. In 2001, 1.1 million Americans were expected to have a new or recurrent myocardial infarction. Approximately one third to one half of patients who experience their first myocardial infarction will die as a result of complications related to their acute event. Despite modern pharmacologic support, cardiogenic shock, defined as inadequate tissue perfusion resulting from a decline in cardiac output, is still a highly lethal complication of an acute myocardial infarction. 
     A variety of left ventricular assist devices have been developed to support the failing myocardium. The intraaortic balloon pump (IABP), which assists the ischemic ventricle through improving coronary perfusion and reducing systemic vascular resistance by counterpulsation, is by far the most widely used left ventricular assist device. The conventional IABP catheter comprises a central lumen for passage of a guidewire during insertion and for monitoring aortic blood pressure. A balloon made of polyurethane is mounted on the catheter and communicates with an outer lumen that provides a passageway for gas exchange and is connected to a console that synchronizes inflation and deflation with the cardiac cycle. The principal of counterpulsation works by deflating the balloon during systole, resulting in a reduction in systemic afterload and vascular resistance. The balloon is inflated during diastole resulting in an improvement of left ventricular performance through an increase in coronary perfusion and a decrease in myocardial oxygen consumption. Counterpulsation also causes an increase in peripheral blood flow. 
     Counterpulsation has been found to be successful in reversing the shock state in 80 to 85 percent of patients with cardiogenic shock after myocardial infarction. Counterpulsation is also very effective in the initial stabilization of patients with mechanical intracardiac defects complicating myocardial infarction, such as acute mitral regurgitation and ventricular septal defect. Other uses of counterpulsation include (1) treating patients with unstable angina, (2) weaning patients from cardiopulmonary bypass, (3) providing mechanical support for patients in heart failure while waiting for cardiac transplant, and (4) prophylactic application in patients with severe left ventricular dysfunction prior to or during surgery or percutaneous angioplasty. 
     At the present time, balloons on the IABP catheter for percutaneous insertion are available in 30 cc, 40 cc, and 50 cc volumes. Although the sizes and design of these balloons are somewhat successful in improving cardiac performance, a relatively large balloon size is required to accomplish adequate displacement of blood volume during its inflation, and to accomplish adequate backflow of blood volume during its deflation. Large balloon size is required because, during inflation, blood is displaced not only upstream (as intended for cardiac assist), but also downstream (unproductive for cardiac assist), and therefore a substantial volume of blood is dispersed to the peripheral vasculature. Likewise, during deflation, backflow occurs to draw blood not only from upstream (as intended to reduce afterload), but also from downstream (unproductive for cardiac assist), and therefore substantial backflow is wasted on drawing blood from the peripheral vasculature. Thus, new devices and methods are needed for increasing the displacement and backflow efficiency of the intraaortic balloon pump and counterpulsation, while decreasing balloon size. 
     SUMMARY OF THE INVENTION 
     The present invention relates to devices and methods for mechanically assisting the pumping action of the heart. In one embodiment, the device comprises a catheter comprising an elongate member having a proximal end and a distal region. The catheter further comprises an expandable member (e.g., a balloon or impermeable membrane) attached in the distal region and an inflatable member in the distal region and attached distal the expandable member. The inflatable member (e.g., a balloon) typically has a volume of between 10-30 cc. The catheter has a lumen that communicates with the inflatable member and extends proximally. 
     The catheter may also have a guidewire lumen. In certain cases, the catheter is further provided with a first blood pressure measuring mechanism for measuring blood pressure between the expandable member and the inflatable member, and a second blood pressure measuring mechanism for measuring blood pressure upstream the inflatable member. The pressure measuring mechanism may take the form of either a pressure lumen that communicates with an external blood pressure transducer or a blood pressure transducer mounted on the catheter. 
     In use, the distal end of the catheter is advanced into the aorta and typically positioned so that the expandable member and the inflatable member are within the descending aorta. The expandable member is expanded to partially obstruct (e.g., to achieve 60% or more, 70% or more, 80% or more, or 90% or more luminal obstruction) or to fully obstruct the aorta. Where the expandable member is a balloon, it can be filled with saline or a gas (e.g., carbon dioxide or helium). The expandable member may be maintained in an expanded state during systole and diastole with either complete or partial aortic obstruction. Alternatively, the expandable member is cycled between an expanded state and a contracted state. If the expandable member is cycled, then typically it will be expanded before inflating the inflatable member, and contracted after deflating the inflatable member. That is, the expandable member may be timed with the cardiac cycle as is the inflatable member. Moreover, the expandable member may be a volume displacement member in the manner of the inflatable member. 
     After the expandable member is expanded to at least partially obstruct the aorta, the inflatable member is inflated with a gas (e.g., carbon dioxide or helium) during diastole and deflated by withdrawing the gas during systole, i.e., the ejection phase of the left ventricle. In certain cases, the methods will include measuring an electrocardiogram and synchronizing inflation with the R wave of the electrocardiogram, so that maximum inflation occurs at the peak of the T wave (which corresponds approximately with closure of the aortic valve), and deflation is timed to occur just before the next QRS complex of the electrocardiogram (which correlates with ventricular systole). Alternatively, synchronization can be accomplished using (1) an arterial waveform from an arterial line in the radial or femoral artery (upstroke of arterial mode is sensed by console), or (2) an external pacemaker, where inflation is timed to occur at the pacing artifact (i.e., pacemaker spike). By repeating this cycle of inflating with a gas during diastole and deflating by withdrawing the gas during systole, the pumping action of the heart is mechanically assisted by (1) reducing systemic afterload, (2) increasing coronary perfusion, and (3) decreasing myocardial oxygen consumption. Moreover, cerebral blood flow is also augmented by the combined action of the inflatable member and the expandable member. 
     Other methods of using the devices of the invention will include measuring a physiologic parameter, and adjusting the expansion of the expandable member based on the measured physiologic parameter. In certain cases, the physiologic parameter is blood pressure measured at a location upstream the expandable member and/or downstream the expandable member. In other cases, the physiologic parameter is cerebral blood flow. Still other methods will include deploying an interventional catheter (e.g., PTCA, stent, atherectomy, thrombectomy, ablation, electrophysiology, laser) or diagnostic catheter (e.g., angiography, ultrasound, fiber optics, optical coherence tomography) slideably inserted through the guidewire lumen of the catheter. 
     In another embodiment, the catheter is designed to achieve a propagated volume displacement toward and away from the heart. The catheter comprises an elongate tubular member having a proximal end, a distal end, and a distal region. A first balloon is attached to the elongate tubular member at the distal region and communicates with a first inflation lumen. The first balloon has an inflation volume of 10-30 cc. A second balloon is also attached to the elongate tubular member at the distal region and located distal the first balloon, and communicates with a second inflation lumen. The second balloon has an inflation volume of 10-30 cc. A third balloon is attached to the elongate tubular member at the distal region and located distal the second balloon, and communicates with a third inflation lumen. The third balloon has an inflation volume of 10-30 cc. 
     A blood pressure measuring mechanism may be included for measuring blood pressure upstream of the third balloon, between the second and third balloon, between the first and second balloon, and/or downstream to the first balloon. The one or more pressure measuring mechanisms may take the form of either a pressure lumen that communicates with an external blood pressure transducer or a blood pressure transducer mounted on the catheter. During use, the first, second, and third balloons are sequentially inflated during diastole to propagate blood flow retrograde to the coronary and carotid arteries. The third, second, and first balloons are then sequentially deflated during the ejection phase of the left ventricle to propagate blood flow antegrade and mechanically assist the pumping action of the heart. 
     The catheter may optionally further include a fourth balloon attached to the elongate tubular member at the distal region, that communicates with a fourth inflation lumen. The fourth balloon is located distal the third balloon and has an inflation volume of 10-30 cc. The catheter may optionally include a fifth balloon attached to the elongate tubular member at the distal region, that communicates with a fifth inflation lumen. The fifth balloon is located distal the fourth balloon and has an inflation volume of 10-30 cc. The catheter may further include an additional lumen that extends from the proximal end to the distal region and is adapted to slideably receive and pass a guidewire and/or an interventional catheter. 
     In use, the distal end of the catheter is advanced into the aorta, and typically is placed so that the first, second, and third balloons are positioned in the descending aorta. The first balloon, the second balloon, and the third balloon are sequentially inflated during diastole to partially or fully obstruct the aorta, thereby propagating blood flow retrograde to the coronary arteries and the carotid arteries. After balloon inflation, the third balloon, the second balloon, and the first balloon are sequentially deflated during the ejection phase of the left ventricle to draw blood flow antegrade. Where optional fourth and fifth balloons are present, these balloons are included in the inflation and deflation sequence. 
     Here too, the methods will include measuring an electrocardiogram and synchronizing inflation with the R wave of the electrocardiogram, so that maximum inflation occurs at the peak of the T wave (which corresponds approximately with closure of the aortic valve), and deflation is timed to occur just before the next QRS complex of the electrocardiogram (which correlates with ventricular systole). Alternatively, synchronization can be accomplished using (1) an arterial waveform from an arterial line in the radial or femoral artery (upstroke of arterial mode is sensed by console), or (2) an external pacemaker, where inflation is timed to occur at the pacing artifact (i.e., pacemaker spike). 
     By repeating this cycle of sequentially inflating the balloons with a gas during diastole and sequentially deflating the balloons by withdrawing the gas during systole, the pumping action of the heart is mechanically assisted by (1) reducing systemic afterload, (2) increasing coronary perfusion, and (3) decreasing myocardial oxygen consumption. Moreover, cerebral blood flow is also augmented by the combined action of the inflatable member and the expandable member. 
     In still another method for mechanically assisting the pumping action of the heart, a catheter is provided comprising an elongate member having a proximal end and a distal region. The catheter further includes an expandable member attached in the distal region and an inflatable member in the distal region and attached proximal the expandable member. The catheter is equipped with a lumen that communicates with the inflatable member and extends proximally and, where the expandable member is also a balloon, a second lumen that communicates with the expandable member. The catheter is inserted into a subclavian artery, and then the distal end of the catheter is advanced into the aorta. The expandable member is expanded to at least partially obstruct the aorta. The inflatable member is then inflated during diastole and deflated during the ejection phase of the left ventricle. The pumping action of the heart is thereby mechanically assisted in the manner described herein above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  depicts a distal region of an embodiment of the intraaortic balloon pump catheter according to the present invention. 
         FIG. 1B  depicts a proximal region of the catheter of  FIG. 1A . 
         FIG. 2A  depicts a distal region of another embodiment of the intraaortic balloon pump catheter having an additional lumen for introducing interventional devices. 
         FIG. 2B  depicts a proximal region of the catheter of  FIG. 2A . 
         FIG. 3  depicts a distal region of another embodiment of the intraaortic balloon pump catheter having three inflatable balloons. 
         FIG. 3A  depicts a cross-sectional view of the catheter of  FIG. 3  through section line A-A. 
         FIG. 4  depicts a distal region of another embodiment of the intraaortic balloon pump catheter having four inflatable balloons. 
         FIG. 4A  depicts a cross-sectional view of the catheter of  FIG. 4  through section line A-A. 
         FIG. 5A  depicts insertion of a guidewire through a needle in the right femoral artery in preparation for introduction of an intraaortic balloon pump catheter. 
         FIG. 5B  depicts insertion of an intraaortic balloon pump catheter through a dilator-introducer in the right femoral artery. 
         FIG. 6A  depicts inflation of the balloons of the intraaortic balloon pump catheter of  FIG. 1A  in the aorta. 
         FIG. 6B  depicts deflation of a balloon of the catheter in  FIG. 6A  to reduce cardiac afterload. 
         FIG. 7A  depicts inflation of balloons of the intraaortic balloon pump catheter of  FIG. 4  in the aorta. 
         FIG. 7B  depicts inflation of another balloon of the catheter of  FIG. 7A . 
         FIG. 7C  depicts inflation of all the balloons of the catheter of  FIG. 7B  to increase coronary blood flow. 
         FIG. 7D  depicts sequential deflation of balloons in the distal region of the catheter of  FIG. 7C  to assist in cardiac afterload reduction. 
         FIG. 7E  depicts deflation of the balloons in the distal region of the catheter of  FIG. 7C  to assist in cardiac afterload reduction. 
     
    
    
     DETAILED DESCRIPTION 
     An embodiment of the intraaortic balloon pump catheter having improved volume-displacement efficiency is shown in  FIGS. 1A and 1B . Catheter  1  comprises elongate tubular member  10  having lumen  15  extending between distal end  11  and proximal end  12 . First balloon  21  is attached to catheter  1  at the distal region. Second balloon  22  (typically made from a thin film of polyurethane because of its strength and antithrombotic properties) is attached to catheter  1  distal to first balloon  21 . Lumen  15  of the catheter communicates with balloon  22  for inflation of the second balloon. Similarly, lumen  16  of the catheter communicates with balloon  21  for inflation of the first balloon. Pressure lumen or manometer  19 , adapted for measuring blood pressure between balloons  21  and  22 , is located distal to balloon  21 . Pressure lumen or manometer  20 , adapted for measuring blood pressure upstream balloon  22 , is located distal balloon  22 . At proximal end  12  of catheter  1  as depicted in  FIG. 1B , port  24 , port  25 , and port  26  are housed within catheter hub  28 . Port  25  communicates with lumen  15  and is adapted for connecting to a console that synchronizes inflation and deflation of balloon  22  with cardiac cycle and makes automatic adjustments for changes in the heart rate and rhythm. Port  26  is adapted for connecting to a console that allows inflation and deflation of balloon  21  independent of cardiac cycle and balloon  22 . Port  24 , which communicates with manometers  19  and  20 , is adapted for connecting to a blood pressure monitor. Where pressure lumens  19  and  20  are present, these lumens communicate separately and independently with separate and independent ports  24   a  and  24   b , which in turn are connected to external manometers. The proximal end of the catheter also includes suture flanges  29  for securing the catheter in place after insertion. 
     Another embodiment of the intraaortic balloon pump catheter having a third lumen adapted for insertion of interventional catheters is shown in  FIGS. 2A and 2B . Lumen  17  communicates proximally with port  27  and distally with port  30 . Interventional catheters, such as an angioplasty catheter, an angiography catheter, a stent deployment catheter, a thrombectomy catheter, an embolectomy catheter, an electrophysiology study catheter, a blood filter, or an intravascular ultrasound catheter, may be introduced through port  27 , lumen  17 , and port  30  to perform desired interventional procedures upstream of catheter  1  when placed in the descending aorta. 
     A further embodiment of an intraaortic balloon pump catheter is depicted in  FIG. 3 . Catheter  1  includes first balloon  21  that communicates with inflation lumen  37 . Second balloon  22  is mounted distal balloon  21 , and communicates with inflation lumen  36 . Third balloon  33  is mounted distal second balloon  22 , and communicates with inflation lumen  35 . Pressure lumen or manometer  19  is mounted distal first balloon  21  for obtaining aortic blood pressure readings upstream balloon  21 . Second pressure lumen or second manometer  20  is mounted distal third balloon  33  for obtaining aortic blood pressure readings upstream balloon  33 . A cross section through section line A-A of catheter  1  is shown in  FIG. 3A . Inflation lumens  35 ,  36 , and  37  are depicted, as well as pressure lumen or manometer lumen  40 . It will be understood that where the catheter includes pressure lumens  19  and  20  each communicating at a proximal end with an external manometer, pressure lumen  40  will actually be comprised of two separate and independent pressure lumens  40   a  and  40   b  (see  FIG. 4A ), each of which communicates with a separate and independent proximal port  24   a  and  24   b , each of which is connected to a separate and independent external manometer. 
     In another embodiment, catheter  1  is equipped with four balloons, as shown in  FIG. 4 . Catheter  1  includes first balloon  21  communicating with inflation lumen  37 . Second balloon  22  is mounted distal first balloon  21 , and communicates with inflation lumen  36 . Third balloon  33  is mounted distal second balloon  22 , and communicates with inflation lumen  35 . Fourth balloon  44  is mounted distal third balloon  33 , and communicates with inflation lumen  38 . Pressure lumen or manometer  19  is mounted distal first balloon  21  for obtaining aortic blood pressure readings upstream balloon  21 . Second pressure lumen or second manometer  20  is mounted distal fourth balloon  44  for obtaining aortic blood pressure readings upstream balloon  44 . A cross section through section line A-A of catheter  1  is shown in  FIG. 4A . Inflation lumens  35 ,  36 ,  37 , and  38  are depicted, as well as pressure lumens  40   a  and  40   b  which communicate separately with pressure elements  19  and  20 , respectively. Catheter  1  of  FIG. 4  also includes lumen  50  shown in  FIG. 4A  for passing an interventional or diagnostic catheter to a location (coronary arteries, carotid arteries, mitral valve, aortic valve, or other arteries of the bead and neck) upstream catheter  1 . 
     In use, the catheter is deployed though a femoral artery as shown in  FIGS. 5A and 5B . After the right groin is sterile prepared, needle  60  is inserted into right femoral artery  55 . Guidewire  61  is inserted through needle  60 , and is advanced into right femoral artery  55  and then into aorta  99  where it will be positioned in the thoracic aorta. Needle  60  is then removed and dilator/introducer  62  is inserted over guidewire  61  as shown in  FIG. 5B , or alternatively, catheter  1  may be inserted over the guidewire without the use of a dilator/introducer  62 . Catheter  1  is then advanced over guidewire  61  and through introducer/dilator  62 . The catheter is then advanced under fluoroscopy (to visualize one or more radio-opaque markers mounted on the distal region of catheter  1 ) until the distal end of the catheter is positioned approximately 2 centimeters downstream of the orifice of the left subclavian artery ( 98  in  FIG. 6A ). The guidewire may then be withdrawn from the patient, or alternatively the guidewire may be left in place to be used during a later interventional catheterization. 
     With the catheter now in place as shown in  FIG. 6A , the inflation lumen for balloon  22  is connected proximally to a console that synchronizes inflation and deflation with the cardiac cycle and makes automatic adjustment for changes in heart rate and rhythm. Balloon  21  is then expanded to partially or fully obstruct aorta  99 . Balloon  21  will be maintained expanded to 60% or more, 70% or more, 80% or more, 90% or luminal obstruction to achieve coarctation and enhancement of cerebral blood flow that is highly advantageous in a patient suffering a cerebral vascular accident. In this regard, Barbut et al., U.S. application Ser. No. 09/841,929, filed Apr. 24, 2001, is incorporated herein by reference in its entirety as if fully set forth herein. Maintenance of balloon  21  in an expanded state also enhances the efficiency of counterpulsation balloon  22 . Balloon  22  is then expanded during diastole ( FIG. 6A ) to enhance coronary perfusion, and deflated during systole ( FIG. 6B ) to reduce afterload in the manner described herein above. Throughout the procedure, blood pressure upstream second balloon  22  may be monitored by readings from pressure lumen or manometer  20  and blood pressure between second balloon  22  and first balloon  21  may be monitored by readings from pressure lumen or manometer  19 . 
     In using the intraaortic balloon pump catheter of  FIG. 4 , placement in the thoracic aorta is accomplished as described herein above, as shown in  FIGS. 7A through 7E . The lumens of balloons  22 ,  33 , and  44  are connected proximally to a console that synchronizes inflation and deflation with the cardiac cycle and makes automatic adjustment for changes in heart rate and rhythm. Balloon  21  is then expanded to partially or fully obstruct aorta  99 . Balloon  21  will be maintained expanded to 60% or more, 70% or more, 80% or more, 90% or more luminal obstruction to achieve coarctation and enhancement of cerebral blood flow which is highly advantageous in a patient suffering a cerebral vascular accident. Maintenance of balloon  21  in an expanded state also enhances the efficiency of counterpulsation balloons  22 ,  33 , and  44 . 
     As shown in  FIG. 7A , the inflation cycle begins with counterpulsation balloon  22  during diastole. Volume displacement occurs predominantly upstream because balloon  21  blocks volume displacement downstream. The expansion of balloon  22  is followed immediately by expansion of balloon  33  as shown in  FIG. 7B . Again volume displacement occurs predominantly upstream, enhancing coronary perfusion and myocardial oxygenation. Expansion of balloon  33  is followed immediately by expansion of balloon  44  as shown in  FIG. 7C . Once again volume displacement occurs predominantly upstream. The diastolic phase of the cardiac cycle is followed by the systolic phase of the cardiac cycle in which blood is ejected from the left ventricle following left ventricular contraction. During this phase of the cardiac cycle, the balloons of catheter  1  are deflated to cause in reduction of left ventricular afterload and systemic vascular resistance. As shown in  FIG. 7D , balloon  44  is first deflated to cause downstream volume reduction. Deflation of balloon  44  is followed immediately by deflation of balloon  33 . Volume reduction again draws blood from the left ventricle downstream. Deflation of balloon  33  is followed immediately by deflation of balloon  22  as shown in  FIG. 7E . The sequential deflation of balloon  44 ,  33 , and  22  is accomplished while balloon  21  is maintained in an expanded state so that volume reduction pulls blood downstream from the left ventricle, not upstream from the peripheral vasculature. 
     While intraaortic balloon pumping is being conducted using any of the devices described herein, it may be desirable to advance an interventional therapeutic or diagnostic catheter through a lumen of catheter  1  and beyond the distal tip in order to access a coronary obstruction, a diseased heart valve, a perforated septum, a ventricular thrombus, a stenosed carotid artery, arrythmiogenic myocardial tissue, and other lesions affecting the arteries of the head and neck. 
     The catheters in accordance with the devices described herein will typically have a length between approximately 75-150 cm, preferably approximately 80-110 cm. Balloon inflation volume will typically be approximately 10-40 cc for each balloon, preferably approximately 20-25 cc. The foregoing ranges are set forth solely for the purpose of illustrating typical device dimensions. The actual dimensions of a device constructed according to the principles of the present invention may obviously vary outside of the listed ranges without departing from those basic principles. 
     Although the foregoing invention has, for the purposes of clarity and understanding, been described in some detail by way of illustration and example, it will be obvious that certain changes and modifications may be practiced which will still fall within the scope of the appended claims.