for Right Ventricular Failure: 11. Clinical Experience

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1 Pulmonary Artery Balloon Counterpulsation for Right Ventricular Failure: 11. Clinical Experience John M. Moran, M.D., Milos Opravil, M.D., Andrew J. Gorman, Ph.D., Hassan Rastegar, M.D., Sheridan N. Meyers, M.D., and Lawrence L. Michaelis, M.D. ABSTRACT The use of pulmonary artery balloon counterpulsation (PABC) provided immediate salvage following cardiac surgical procedures in 2 patients with biventricular failure in whom inotropic drugs and intraaortic balloon counterpulsation did not provide sufficient support to allow weaning from cardiopulmonary bypass. Although both patients eventually died, the hemodynamic effectiveness of PABC was documented. The various clinical settings for right ventricular as well as biventricular failure are reviewed, the currently available options for treatment are summarized, and the directions for future laboratory investigation and possible clinical applications are presented. Cardiac assist devices have been designed primarily to aid the failing left ventricle because of the obvious importance of left ventricular function to overall cardiac performance. With failure of left ventricular function due to a variety of causes, the effectiveness of intraaortic balloon counterpulsation (IABC) has proven itself beyond doubt and has provided notable salvage in terms of survival and quality of life. Right ventricular assist, on the other hand, has received very little attention either experimentally or clinically. There are a number of situations in which primary right ventricular failure in the presence of normal left ventricular function may result in low cardiac output and death. These include right ventricular infarction, primary and secondary pulmonary hypertension, pulmonary embolization, a variety of congenital anomalies, and surgical absence of the pulmonary valve. More common than isolated right ventricular failure, however, is secondary right heart failure that is caused by left ventricular failure. This is seen most often in the postoperative setting after various procedures that involve a compromised left ventricle resulting from either underlying myocardial disease or inadequate myocardial protection. Clinical Material We have encountered 2 patients with biventricular failure in whom weaning from cardiopulmonary bypass From the Department of Surgery, Cardiothoracic Division, and Department of Medicine, Section of Cardiology, Northwestern University, Chicago, IL. Accepted for publication Dec 12, Address reprint requests to Dr. Moran, Division of Cardiothoracic Surgery, Brown University, 110 Lockwood St, Providence, RI was unsuccessful despite the use of IABC and in whom pulmonary artery balloon counterpulsation (PABC) was employed. Patient 1 A 71-year-old man experienced out-of-hospital ventricular fibrillation with sudden death. At subsequent electrophysiological study with programmed stimulation, ventricular tachycardia was induced readily and degenerated to ventricular fibrillation. Angiocardiography revealed a large apical and interventricular septal aneurysm, an ejection fraction of approximately 30%, occlusion of the left anterior descending and right coronary arteries with poor visualization of both vessels beyond the occluded portion, and a large circumflex system reconstituted primarily as an obtuse marginal artery with a tight stenosis at its origin. Forty-eight hours prior to operation, the patient experienced an episode of ventricular fibrillation that required prolonged cardiopulmonary resuscitation. It was believed that operative intervention was his only hope for survival. On December 24, 1981, epicardial and endocardia1 mapping, left ventricular aneurysmectomy with endocardial resection and septal patch, and single saphenous vein bypass to the obtuse marginal artery were carried out. With attempts to wean the patient from cardiopulmonary bypass, it became apparent that unassisted myocardial performance would be inadequate for survival; intensive inotropic support had failed. Because the patient had extensive aortoiliac occlusive disease, a 40 cc intraaortic balloon was placed in the descending thoracic aorta through the ascending aorta to provide counterpulsation support. With IABC there was temporary improvement in the quality of left ventricular contraction. Pulmonary artery diastolic pressures ranged from 25 to 30 mm Hg. Right ventricular contraction progressively diminished, with increasing distention, and feeble contractions were seen only in the region of the infundibulum, despite the combination of IABC and inotropic support. The decision was made to attempt PABC. A 20 mm Dacron graft was sewn onto the pulmonary artery, and a 40 cc intraaortic balloon was inserted well into the pulmonary tree until it would go no farther; it was then withdrawn slightly. The graft was secured around the balloon catheter with heavy ligatures, and pulmonary artery pumping was begun. With manipulation of timing of the two consoles, effective counterpulsation was achieved in both the pulmonary artery and the aorta. There was visible improvement in the quality of contraction of the right ventricle, the augmented sys- 254

2 255 Moran et al: Balloon Counterpulsation in RV Failure: 11. Clinical Experience Fig 1. (Patient 1.) Chest roentgenogram showing position ofpulrnonary artery balloon in the left pulmonary artery. The circle surrounds the marker at the end of the balloon. temic arterial systolic pressure ranged from 90 to 100 mm Hg, and the pulmonary artery diastolic pressure ranged from 20 to 25 mm Hg. Both balloon catheters were brought out in the subxiphoid area. The wound was closed, and the patient was transferred to the cardiac surgical intensive care unit. Chest roentgenogram revealed that the pulmonary artery balloon tip had been positioned well out in the left pulmonary artery (Fig 1). With adjustment of inotropic drug management and balloon timing, there was gradual improvement over the next 3 hours. The arterial systolic pressure ranged from 110 to 120 mm Hg, the pulmonary artery diastolic pressure was 25 to 30 mm Hg, and the cardiac output was 3.5 liters per minute. With 1 : 1 PABC, the radial artery pressure was 100/70 mm Hg and there was excellent pulmonary artery augmentation with a pressure of 65/28 mm Hg. With the pulmonary artery balloon pump turned down to 1 : 3 while maintaining 1 : 1 IABC, the radial artery pressure fell to mm Hg and the pulmonary artery diastolic pressure became elevated to 35 mm Hg (Fig 2). Further improvement continued during the next 12 hours. The patient awakened, was responsive, and moved all his extremities, and urinary output was excellent. The cardiac output was now 4 L/min. Dependence on pulmonary artery balloon support was demonstrated even more dramatically, with the radial artery systolic pressure falling precipitously by 15 mm Hg (from 100 to 85 mm Hg) with temporary discontinuation of PABC. Gradual improvement continued. Inotropic support was gradually being withdrawn when there was a failure of the pulmonary artery console such that neither filling of the balloon nor counterpulsation could be achieved. There was a 15-minute delay while another console was obtained; during this period, progressive hemodynamic deterioration took place. By the time the second console was functioning, the systemic arterial systolic pressure had dropped to 50 mm Hg. Progressive hemodynamic deterioration resulted in death within 2 hours. Cardiac output measured 5 minutes after discontinuation of pulmonary artery pumping had fallen to 2.5 L/min, thus quantitating the profound dependence on pulmonary artery pumping. Postmortem examination revealed intact septa1 patch and aneurysm repair as well as a patent vein graft. There was no thrombus on either balloon, and the pulmonary artery showed no sign of trauma where the balloon had resided. Patient 2 A 68-year-old man underwent extensive endocardia1 resection, aneurysmectomy, and single aortocoronary bypass for intractable ventricular tachycardia on December 17,1981. Subsequently, he had a reasonably satisfactory convalescence and was discharged from the hospital. Five weeks after operation, he began to experience increasing shortness of breath and was readmitted. Diagnostic studies revealed absence of ventricular arrhythmia, but there was moderate congestive failure. Pulmonary angiography showed abundant clot primarily in the right pulmonary artery; the pulmonary artery pressure was approximately 70/40 mm Hg. Following angiography, and despite fibrinolytic therapy, dyspnea and tachypnea increased. The pulmonary artery pressure remained elevated, and gradually the systemic arterial systolic pressure diminished to approximately 70 mm Hg despite increasing doses of dopamine. In this setting, it was believed that pulmonary embolectomy was necessary. As the mediastinum was entered through the previous sternotomy and both pleurae were opened, the lungs were noted to be very pale. After institution of cardiopulmonary bypass, the pulmonary artery was opened longitudinally. Despite pulmonary massage, irrigation, and the use of embolectomy catheters, only minimal clot was removed, primarily in the form of sludge. The lungs were now pink; after closure of the pulmonary arteriotomy and gradual weaning from cardiopulmonary bypass, there was marked improvement in gas exchange. Subsequently, however, failure of both ventricles developed. An attempt to insert an intraaortic balloon pump through the left femoral artery was unsuccessful because of abdominal aortic obstruction; a descending thoracic intraaortic balloon was then placed using the same technique as for Patient 1, with a 50 cc balloon. Subsequently, Patient 2 did well while off cardiopulmonary bypass for about 40 minutes; however, his condition gradually deteriorated with the pulmonary artery diastolic pressure rising to 40 mm Hg and the radial artery pressure falling to 70 mm Hg despite optimal inotropic support. At this point, a 20 mm Dacron graft was sewn to the lower end of the pulmonary artery incision and a 40 cc balloon inserted into the right pulmonary artery as far as it would comfortably go, with about half the balloon remaining outside the pulmonary

3 256 The Annals of Thoracic Surgery Vol 38 No 3 September 1984 IABP 111 IABP I I PABP I I PABP RADIAL ARTERY / PULMONARY ARTERY 50/35 Fig 2. (Patient 1.) Effect of 2:Z and 1:3 pulmonary artery balloon pumping (PABP) on radial artery and pulmonary artery pressures. lntraaortic balloon pumping (IABP) was maintained at 2 :1 for both levels of pulmona y balloon counterpulsation. artery in the Dacron graft. Following this procedure, there was immediate hemodynamic improvement. The incision was closed, and the patient was transferred to the intensive care unit with a systemic arterial systolic pressure of 100 mm Hg and a pulmonary artery diastolic pressure of 30 mm Hg. Chest roentgenogram showed that the pulmonary artery balloon had been positioned on the right and that the intraaortic balloon was in satisfactory position (Fig 3). Effective tandem counterpulsation was achieved in much the same manner as in Patient l. The patient had been anuric since before the operation. Convulsions developed that progressed gradually Fig 3. (Patient 2.) Chest roentgenogram showing position of pulmonay artey (left upper) and intruuortic balloons. Each circle indicates the markers at the tip of each balloon. to coma, and the abdomen became progressively distended. During the period of tandem pumping with the assistance of dopamine and epinephrine inotropic support, a cardiac output of 5.5 L/min was achieved. Atrial and ventricular arrhythmias developed but were largely suppressed by pacing. The patient died, but prior to his death, after 64 hours of tandem pumping hemodynamic studies were performed with the informed consent of the family (Fig 4). After baseline values were established with both balloon pumps turned off, IABC and then PABC were reinstituted; there was incremental improvement in mean systemic arterial and arterial systolic pressure, pulmonary artery systolic and diastolic pressure, and central venous pressure. The cardiac output in this terminal situation, however, did not improve. At postmortem examination, there was no thrombus in the pulmonary artery graft or on either balloon, and there was no sign of trauma to the right pulmonary artery despite 64 hours of pumping with the balloon well out in the pulmonary tree. The entire small bowel was infarcted, most probably because of a combination of low blood flow state and pressor agents, since no celiac or mesenteric arterial emboli were found. The coronary bypass graft was patent, the aneurysm repair was intact, and a modest amount of residual pulmonary thrombus was found in the distal right pulmonary artery. Comment Isolated Right Ventricular Failure Isolated right ventricular failure in the presence of good left ventricular function is not uncommon as a cause of low cardiac output and death following cardiac surgical procedures. In this clinical situation, those at risk are patients who have right ventricular hypertrophy and pulmonary hypertension following mitral valve procedures; patients with right ventricular infarction, including those who have relatively good left ventricular function but poor right ventricular function, following repair of acquired ventricular septa1 defect; patients who have had poor myocardial protection of the right ventricle compared with the left following coronary revascularization; patients who undergo repair of congenital anomalies that are characterized by right ventricular trauma, pulmonary hypertension, and absence of the pulmonary

4 257 Moran et al: Balloon Counterpulsation in RV Failure: 11. Clinical Experience RA '"[I BOTH PUMPS OFF IABP ONLY BOTH PUMPS ON /30-70/ PA ' 45/30 47/28 62/27... _. CVP I8 CO I Fig 4. (Patient 2.) Hemodynarnic studies done after 64 hours of tandem pumping. (IABP = intraaortic balloon pumping; RA = right atrial [pressure]; PA = pulmonary artery lpnssurel; CVP = central venous pressure; CO = cardiac output.) valve; and patients who have residual pulmonary hypertension and acute right ventricular failure following pulmonary embolectomy. In each of these clinical settings, support for the failing right ventricle without the need for left heart assist would be appropriate. Fledge and colleagues [l] have claimed the first successful clinical experience with PABC for isolated right heart failure by utilizing the method of Miller and associates [2], who had previously described the use of intraaortic balloons placed in a graft sewn to the pulmonary artery. A patient who had undergone mitral valve replacement could not be weaned from cardiopulmonary bypass because of profound right heart failure in the presence of low to normal left heart filling pressures and vigorous left ventricular contraction. After the institution of PABC through a graft sewn to the pulmonary artery, the patient was readily weaned from the pump. Progressive hemodynamic improvement occurred over the next three days, at which time operative removal of the pulmonary artery balloon was performed. The patient is currently asymptomatic 26 months after operation. Biventricular Failure The entity that most commonly predisposes to biventricular failure postoperatively is a left ventricle previously compromised by such complications of myocardial infarction as aneurysm, ventricular septal defect, ischemic mitral incompetence, and the diffusely scarred hypokinetic ventricle. Complex corrective procedures, often requiring additional operative time and trauma, may include valve replacement or septal defect repair in addition to aneurysmectomy, endocardia1 resection for treatment of malignant ventricular rhythm disturbances, and performance of multiple coronary artery bypass grafts. In addition, inadequate myocardial protection, especially of the vulnerable right ventricle, may contribute to biventricular failure in procedures for valvular and congenital heart disease, as well as in ischemic heart disease. Several groups of investigators have studied the interdependence of the two ventricles, including the dependence of ventricular distensibility on filling of the opposite ventricle [3-61. Some work indicates that this interdependence may be more significant with the open pericardium, as seen in the postbypass condition [7, 81. The role of the infarcted, scarred, and akinetic or aneurysmal septum is open to speculation, but in all probability it intensifies such interdependence. Pierce and colleagues [9] recently reviewed their 5-year experience with univentricular and biventricular extracorporeal assist. They documented an "unmasking" of right ventricular failure by the increased preload brought about by the left ventricular assist device. In two instances, they applied the assist device to the right atrium and pulmonary artery with hemodynamic improvement, but death resulted from causes other than biventricular failure. Lefemine [lo] also reviewed the interdependence of the two ventricles and the practical applications of biventricular assist, using extracorporeal circulation without an oxygenator, when right ventricular failure is recognized following the institution of left heart bypass. Parr and associates [ll] described 2 patients with biventricular failure after left ventricular anteroseptal aneurysmectomy who were salvaged. One patient fortuitously had a patent foramen ovale, which provided right heart decompression at the cost of partial desaturation; the other represents the only reported example to date of right heart extracorporeal pump assist without accompanying left ventricular assist, although IABC was utilized for left heart support. Miller and co-workers [2] reported one of the first clinical applications of PABC in the setting of biventricular failure and arrhythmias after repeat coronary bypass procedure that did not respond to IABC alone. The tech-

5 258 The Annals of Thoracic Surgery Vol 38 No 3 September 1984 nique they described involves inserting the intraaortic balloon into a 20 mm Dacron graft sewn to the main pulmonary artery. This technique was also used by Flege and colleagues [l] and in our 2 patients, with the difference that we chose to insert the balloon well into the pulmonary artery with only one-half to one-third of the balloon residing in the graft. In the report of Miller's group [2], the effectiveness of PABC was demonstrated and there was progressive hemodynamic improvement over a 30-hour period until death was caused by arrhythmia. Utilizing a biventricular failure model created by graded coronary embolization, we have demonstrated a synergistic effect of PABC and IABC in improving cardiac output to a greater degree than with either method alone.* In an isolated left ventricular failure model we have also demonstrated deterioration in cardiac output and left ventricular hemodynamics brought about by left heart preload as a result of PABC alone. These findings will be the subject of a future publication. Current Clinical Approaches to Intraoperative Right Ventricular Failure During attempts to wean patients from cardiopulmonary bypass in the high-risk settings described earlier, the surgeon must be aware of the possibility of either isolated right ventricular failure or right ventricular failure secondary to left ventricular dysfunction. As Pierce and colleagues [9] have pointed out, it is important to make prompt decisions concerning the need for both left ventricular and right ventricular assist in order to minimize the time on cardiopulmonary bypass. On the basis of current clinical and experimental evidence, PABC may be expected to provide adequate support in mild to moderate failure, but right ventricular assist by means of right atrium-pulmonary artery cannulation and a roller pump, or by a right ventricular assist device, will undoubtedly be required for severe right heart failure. Alternatives are the creation of an atrial septa1 defect to achieve right ventricular unloading at the expense of partial desaturation or the use of peripheral venoarterial bypass. Since PABC is the least invasive method of all those available, its initial use would seem justified. In regard to left ventricular failure, Robinson and associates [12] have demonstrated increasingly effective metabolic and functional support of the left ventricle by IABC, left atrium-aorta bypass, and left ventricular assist devices. It may reasonably be expected that the right ventricle will respond similarly to this gradation of support systems. " Future Directions The limited experience to date with use of an intraaortic balloon for clinical PABC, together with experimental evidence for lack of acute pulmonary artery or pulmo- 'Opravil M, Gorman AJ, Moran JM: Right- and left-sided balloon counterpulsation for biventricular failure. (unpublished data, 1983) nary valve trauma, suggests that a dedicated pulmonary artery balloon inserted through the right ventricular outflow tract would be well tolerated in human beings for at least several days. To the end of designing a pulmonary artery balloon for human use, we have taken measurements of the length and diameter of the main pulmonary artery at the time of open-heart operation in 20 consecutive patients. We have also taken measurements of the pulmonary artery and its major branches from 20 pulmonary angiograms. These findings confirm those reported by Dotter and Steinberg [13]. Calculations of volumes of the main and right pulmonary arteries suggest that balloon displacement volumes of 50 to 60 cc could readily be achieved in the individual of average size. The primary advantage of a balloon designed to be inserted through the right ventricular outflow tract and positioned just beyond the pulmonary valve would be the ease of insertion at operation. In addition, the possible insertion of a pulmonary artery balloon through a peripheral vein, most appropriately the femoral vein, would utilize the same basic design. Possible disadvantages of this approach would be trauma to the pulmonary artery or pulmonary valve and absence of a reservoir in which the balloon would reside. Studies currently under way in our laboratory are designed to evaluate pulmonary artery and pulmonary valve trauma with long-term PABC in sheep and to compare the hemodynamics of pumping with and without a reservoir in the form of a pulmonary artery graft. With the design, testing, and approval of a dedicated pulmonary artery balloon for use in human beings and with adequate clinical experience, it is possible that femoral vein insertion will become the method of choice at operation. Moreover, it is conceivable that PABC may occasionally be appropriate in the nonoperative setting for primary or secondary right ventricular failure due to the various clinical conditions mentioned previously. References 1. Flege JB Jr, Wright CB, Reisinger TJ: Successful balloon counterpulsation for right ventricular failure. Ann Thorac Surg 37167, Miller DC, Moreno-Cabral RJ, Stinson EB, et al: Pulmonary artery balloon counterpulsation for acute right ventricular failure. J Thorac Cardiovasc Surg 80:760, Taylor RR, Cove1 JW, Sonnenblick EH, et al: Dependence of ventricular distensibility on filling of the opposite ventricle. Am J Physiol 213:711, Kelly DT, Spotnitz HM, Beiser GD, et al: Effects of chronic right ventricular volume and pressure loading on left ventricular performance. Circulation 44:403, Weiss JL, Brinker JA, Lappe DL, et al: Leftward displacement during right ventricular loading in man: demonstration by two dimensional echo (abstract). Am J Cardiol 41:362, Ludbrook PA, Bryne JD, McKnightRB: Influence of right ventricular hemodynamics on left ventricular diastolic pressure-volume relations in man. Circulation 59:21, Bemis CE, Serur JR, Borkenhagen D, et al: Influence of right

6 259 Moran et al: Balloon Counterpulsation in RV Failure: 11. Clinical Experience ventricular filling pressure on left ventricular pressure and dimension. Circ Res 34:498, Ross J Jr: Acute displacement of the diastolic pressure volume curve of the left ventricle: role of the pericardium and the right ventricle (editorial). Circulation 29:32, Pierce WS, Parr GVS, Myers JL, et al: Clinical effectiveness of mechanical ventricular bypass in treating postoperative heart failure. Artif Organs 7:25, Lefemine AA: Low flow right atrial and left ventricular assist device without an oxygenator for cardiogenic shock: a revised concept. In Unger F (ed): Assisted Circulation. Berlin, Springer-Verlag, Parr GVS, Pierce WS, Rosenberg G, et al: Right ventricular failure after repair of left ventricular aneurysm. J Thorac Cardiovasc Surg 80:79, Robinson WJ, Daly BDT, Hughes DA, et al: An abdominal left ventricular assist device: preclinical studies. Ann Thorac Surg 19:540, Dotter CT, Steinberg I: The angiocardiographic measurement of the normal great vessels. Radiology 52:353, 1949