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PubMed1991

Skeletal muscle extraaortic counterpulsation. A true arterial counterpulsation.

Reduction of left ventricular work load during systole, a critical component of arterial counterpulsation, has not previously been documented for skeletal muscle-powered extraaortic counterpulsation. To assess its capacity for afterload reduction, a skeletal muscle extraaortic counterpulsator was connected to the thoracic aorta and counterpulsated. Canine hearts (n = 7) were instrumented with left ventricular Millar catheters (Millar Instruments, Inc., Houston, Tex.) for pressure measurements and with piezoelectric ultrasonic crystals for measurement of the left ventricular minor axis dimension and wall thickness. During systole, skeletal muscle extraaortic counterpulsation resulted in a significant change in all three determinants of left ventricular circumferential wall stress compared with control conditions (no counterpulsation). Pressure decreased (peak systole, 100 +/- 5 versus 75 +/- 6 mm Hg; p less than 0.05 by paired t test), minor axis dimension decreased (end systole, 46.4 +/- 1.1 versus 45.8 +/- 1.1 mm; p less than 0.05 by paired t test), and wall thickness increased (end systole, 10.4 +/- 0.7 versus 10.6 +/- 0.7 mm; p less than 0.05 by paired t test). Left ventricular wall stress/dimension work loops showed a shift downward and to the left, a shift consistent with afterload reduction. The mean systolic left ventricular wall stress was significantly reduced, from 67.3 +/- 10.6 to 47.7 +/- 8.1 10(3) dyne/cm2 (p less than 0.05 by paired t test). Skeletal muscle extraaortic counterpulsation increased the diastolic aortic pressure from 72 +/- 6 to 105 +/- 8 mm Hg (p less than 0.05 by paired t test). Our data, which documented the counterpulsator's direct effects on left ventricular functional mechanics, showed that skeletal muscle extraaortic counterpulsation is capable of both diastolic augmentation of arterial pressure and systolic unloading of the left ventricle. Skeletal muscle extraaortic counterpulsation has potential application for ventricular unloading in the treatment of chronic end-stage heart failure.

Animals↗

PubMedDate not supplied

Additional salutary hemodynamic effects of the combined use of the paraaortic counterpulsation device and intraaortic balloon pump versus a paraaortic counterpulsation device alone.

The hemodynamic effects of the combined use of the paraaortic counterpulsation device (PACD) (stroke volume 65 ml) implanted on the ascending aorta, and a 20 ml intraaortic balloon pump (IABP) placed in the descending aorta, were compared with the PACD working alone in 12 dogs after the induction of heart failure. Heart failure was characterized by left ventricular end-diastolic pressure (LVEDP) greater than 18 mmHg and systolic aortic pressure (SAP) in stage A: 116 mmHg greater than or equal to SAP greater than 70 mmHg; in stage B: 70 mmHg greater than or equal to SAP greater than 30 mmHg; and in stage C: SAP less than or equal to 30 mmHg. Both modalities of mechanical assistance produced significant salutary hemodynamic effects in stages A and B. No difference was observed in stage C. In conclusion, the combined use of PACD and IABP is more effective than the use of either of these devices alone. This modality of mechanical assistance may easily be applied in patients that cannot be weaned from extracorporeal circulation, and in whom IABP was unsuccessfully applied.

Animals↗

PubMed1990

Implantable rate-responsive counterpulsation assist system.

To apply the potential energy source available from skeletal muscle in cardiac assistance, we developed an implantable counterpulsation assist system. This study reports the results using this implantable counterpulsation assist system in an acute in vivo animal model. Twelve dogs had a dual-chambered, extraaortic counter-pulsation pump anastomosed in parallel to the thoracic aorta. The left latissimus dorsi muscle was used to power the pump. A newly developed implantable stimulator was used to make the muscle contract in synchrony with the diastolic phase. The unique feature of this stimulator is its ability to adjust timing of muscle contraction according to changing heart rates. The stimulator is also able to detect arrhythmias, and as a safety measure, shuts down until a normal rhythm is resumed. During counterpulsation assist with the implantable counterpulsation assist system, diastolic pressure increased an average of 34 mm Hg from baseline, equivalent to a 69% augmentation. Systolic peak pressure decreased an average of 10 mm Hg, equivalent to an 11% unloading. With induced heart rate changes, the implantable counterpulsation assist system readjusted its timing, maintaining optimal counterpulsation without systolic interference. Induced ventricular tachycardia resulted in immediate shutdown of the stimulator until resumption of a normal rhythm. The feasibility of using an intraaortic balloon pump console as back-up was also demonstrated. Excellent counterpulsation was obtained with either muscle power or balloon pump console. We conclude that the implantable counterpulsation assist system can provide effective counterpulsation assist and has the potential for continuous cardiac support.

Animals↗

PubMed1986

Current status of external counterpulsation.

This article traces the development of external counterpulsation from its beginnings to the present. Initially, counterpulsation was carried out by cannulating the femoral artery. The hemodynamic goals were to reduce the afterload of the left ventricle, and to raise or augment the diastolic pressure. This gave rise to the term "counterpulsation." The intra-aortic balloon is capable of producing these salutary effects because of its proximity to the outlet of the left ventricle. The same hemodynamic effects can be obtained by external counterpulsation. However, one must produce a negative pressure during cardiac systole, and ensure that this is applied to the lower extremities. The only clinical study in which this was done was in the treatment of patients in cardiogenic shock by Soroff and colleagues. The results of the clinical studies reviewed are all suggestive of benefits derived from external counterpulsation in a variety of clinical settings. These studies suggest the following avenues for improvement in the equipment used to carry out external counterpulsation: 1. Inclusion of the vascular bed of the buttocks to be subjected to the external pressures, as advocated by Zheng. 2. Inclusion of a negative pressure blanket, as advocated by Soroff. 3. Further investigation of graded-sequential external counterpulsation, using the buttocks and negative pressure. 4. Application of external counterpulsation earlier in cardiogenic shock and for at least 4 hours in acute myocardial infarction. Our evaluation is that this method has not been studied in a way that demonstrates its full potential. We feel that it is on the threshold of being shown to be useful in all of the clinical settings reviewed, and we hope that the necessary equipment will be created to allow investigators to establish its proper place in our therapeutic armamentarium.

Acute Disease↗

PubMed1991

Development of mock circulation models for the assessment of counterpulsation systems.

STUDY OBJECTIVE: This study entailed the development of mock circulation models to assess and compare the haemodynamic efficacy of extra-aortic counterpulsation (using trained skeletal muscle wrapped around the proximal descending aorta) and conventional intra-aortic balloon counterpulsation. DESIGN AND EXPERIMENTAL MATERIALS: Hydraulic Windkessel type lumped parameter models were used either in conjunction with native skeletal muscle or as a dynamic simulation of counterpulsation. The haemodynamic performance of the wrapped latissimus dorsi muscle of the normal sheep was assessed using an artificial load to simulate the pressurised proximal descending aorta. Mock circulation models of counterpulsation comprised Windkessel compliance chambers, laminar flow resistors, a blood analogue, a prosthetic blood pump, and a purpose made hydraulic counterpulsator. MEASUREMENTS AND MAIN RESULTS: An electrically stimulated muscle wrap, 5 cm in length, previously trained for 2 weeks at 3 V and 35 Hz, was assessed for haemodynamic performance in a mock circulation: volume of fluid displaced = 14.1(SD 1.8) ml; pressure increase from 100 mm Hg = 14.9(2.1) mm Hg; external work per contraction cycle = 180(70)mJ; external mean power = 800(100) mW. In a simulation of intra-aortic balloon counterpulsation, haemodynamic benefit (ie, an increase in proximal flow rate and endocardial viability ratio and a reduction in left ventricular stroke power) was assessed with respect to defined parameters. CONCLUSIONS: This paper demonstrates the potential of the mock circulation models both for the investigation of muscle wrap performance and for the comparison of extra-aortic muscle with intra-aortic balloon counterpulsation.

Counterpulsation↗

PubMed1985

Intraaortic balloon counterpulsation as a temporary support measure in decompensated critical aortic stenosis.

Intraaortic balloon counterpulsation was instituted in two adult patients whose condition was rapidly deteriorating because of critical decompensated valvular aortic stenosis. The acute hemodynamic effect of counterpulsation in these patients was compared with the effect of counterpulsation in three control patients with unstable angina and no aortic valve disease. Augmentation of aortic diastolic pressure was similar in both groups; however, in contrast to the patients with unstable angina, the patients with aortic stenosis had no decrease in left ventricular systolic pressure. Counterpulsation resulted in an increase in the transvalvular pressure gradient, which was associated with a slight increase in stroke volume. In both patients with aortic stenosis, the institution of counterpulsation resulted in marked clinical improvement, which facilitated successful valve replacement surgery. The benefit from counterpulsation in critically decompensated aortic stenosis appears to be derived almost entirely from augmentation of the diastolic coronary filling gradient. The improvement that results from counterpulsation suggests that ischemia is the major cause of decompensation.

Acute Disease↗

PubMed1979

Medically refractory unstable angina pectoris. II. Hemodynamic and angiographic effects of intraaortic balloon counterpulsation.

Of 60 patients receiving intraaortic balloon counterpulsation for angina refractory to maximal medical therapy, a subgroup of 10 patients underwent left ventricular angiography both with and without counterpulsation. Severe stenosis of the left anterior descending coronary artery was present in all 10 patients. Counterpulsation resulted in a significant decrease in systolic and end-diastolic left ventricular pressures and no increase in cardiac index. Left ventricular diastolic and systolic volume, ejection fraction and regional contraction patterns, often abnormal, were unchanged. However, mean normalized systolic ejection rate was improved by the addition of counterpulsation. It is concluded that intraaortic balloon counterpulsation has relatively little effect on the left ventricular volume of patients with medically refractory angina pectoris. The symptomatic improvement that takes place seems to occur mainly through the effect of counterpulsation on preload and afterload.

Administration, Oral↗

PubMed1975

[Treatment of cardiogenic shock complicating myocardial infarct by the methods of counterpulsation].

The results of treatment of myocardial infarction complicated by cardiogenic shock by-means of arterial counterpulsation and that with an intra-arterial ballon are presented. In order to determine the indications for counterpulsation the authors introduce a classification of cardiogenic shock that takes into account the reactivity of the patient and the speed of decompensation of the systemic circulation. Both methods of counterpulsation permitted to reverse the cardiogenic shock in 81.8% of the cases. In 18.2% the shock appeared to be areactive in nature, 15.9% of the patients died due to a recurrence of the cardiogenic shock after it had been reversed by means of assisted circulation. Other complications of myocardial infarction caused the death of 43.3% of the rest. Hospital mortality comprised 77.4%. The main factors that determine the stable positive countershock effect of counterpulsation in myocardial infarction cases complicated by cardiogenic shock include early introduction of counterpulsation into the set of therapeutic and resuscitation measures, high capacity of assisted circulation devices (up to 31/min.), long duration of continuous counterpulsation (not less than 12 hours).

Assisted Circulation↗

PubMed1985

Pulmonary artery balloon counterpulsation in the management of right heart failure during left heart bypass.

Pulmonary artery balloon counterpulsation was instituted in 10 pigs when right ventricular failure limited cardiac output. Global myocardial depression was produced by infusion of propranolol, and the left ventricle was fully supported by left heart bypass. A stable model of failure was achieved in six pigs. Following application of pulmonary artery balloon counterpulsation right atrial pressure decreased from 18.2 +/- 2.1 to 15.9 +/- 2.5 mm Hg (p less than 0.05). Cardiac output increased from 416 +/- 94 to 758 +/- 127 ml/min (p less than 0.001). Right ventricular stroke work increased from 0.29 +/- 0.07 to 0.65 +/- 0.12 gm X m. (p less than 0.05). There was no cardiac output before or after institution of balloon counterpulsation in four pigs studied during ventricular fibrillation or asystole. We conclude that pulmonary artery balloon counterpulsation improved cardiac output and right ventricular stroke work in a model of right ventricular failure where the pulmonary circulation was unaltered and the left ventricle supported by left heart bypass. Balloon counterpulsation was not effective during ventricular fibrillation or asystole. Pulmonary artery balloon counterpulsation should be considered when right ventricular failure limits cardiac output during left heart bypass.

Animals↗

PubMed1992

Evaluation of an extraaortic counterpulsation device in severe cardiac failure.

A valveless, single-orifice polyurethane ventricle with a maximum stroke volume of 60 mL was implanted on the brachiocephalic artery just above the aortic arch in sheep (n = 14) to act as an extraaortic counterpulsation device. In parallel, an intraaortic balloon was placed in the descending thoracic aorta. Both devices were pneumatically driven with an intraaortic balloon pump console that was gated by the electrocardiogram to provide aortic diastolic augmentation at a stroke volume of 40 mL. To compare the efficacy of counterpulsation for each device during severe cardiac failure, biventricular block was induced by continuous infusion of esmolol (100 to 600 micrograms.kg-1.min-1), titrated to reduce aortic flow and pressure to less than 75% of baseline. Pulsatile coronary and aortic flows were recorded with ultrasonic flow probes placed around their respective vessels. Aortic root and left ventricular pressures were recorded using micromanometers. The enhancement of hemodynamic variables for both devices were compared for optimal timing conditions, which were defined as inflation set just before the dicrotic notch and deflation bordering on isovolumetric systole. The extraaortic counterpulsation device was able to significantly augment aortic and coronary flows while simultaneously decreasing left ventricular tension time index and aortic end-diastolic pressure (p less than 0.02). The intraarotic balloon pump was able to significantly reduce only tension time index (p less than 0.002) to a lesser extent that the extraaortic counterpulsation device. All analysis was performed with the paired-samples t test. The extraaortic counterpulsation device greatly improves the myocardial oxygen supply-consumption ratio of the left ventricle by increasing diastolic coronary flow and reducing left ventricular wall tension during systole.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

A new implantable burst generator for skeletal muscle powered aortic counterpulsation.

Skeletal muscle (SM) can be used for long-term circulatory assist. To generate contractions of appropriate duration and strength, SM requires bursts of electrical pulse trains. Presently, the implantable pulse train stimulator for SM assist is unable, at different heart rates, to adjust pulse burst duration or delay time, adversely affecting timing of counterpulsation. A prototype implantable microprocessor based stimulator (Medtronic Prometheus) has been developed to address this issue. The purpose of this study was to test this generator in an acute dog model. A dual chambered counterpulsation device was connected to the aorta in six dogs, using the latissimus dorsi to power the pump. The generator was connected by sensing/stimulating leads to the heart/left thoracodorsal nerve, programmed to give bursts of 2 V, 30 Hz, and pulse widths of 180 microsecs. Burst delay and duration was set as a fixed percent of the R-R interval of the EKG. The baseline aortic pressures ranged from 75/33 to 118/87 mmHg. During counterpulsation, diastolic pressure increased from 17 to 50 mmHg (30-111% increase). With changing heart rates, the pulse generator spontaneously readjusted its burst delay and duration, maintaining optimal diastolic counterpulsation without systolic interference. We conclude that this new pulse generator can stimulate SM for counterpulsation at varying heart rates, and is suitable for implantation in chronic studies.

Animals↗

PubMedDate not supplied

Comparison of an extraaortic counterpulsation device versus intraaortic balloon pumping in severe cardiac failure.

A valveless, single orifice polyurethane ventricle was implanted on the brachiocephalic artery in sheep (n = 14) to provide extraaortic counterpulsation. In parallel, an intraaortic balloon was placed in the descending thoracic aorta. Both devices were pneumatically driven by a standard intraaortic balloon pump (IABP) console at a preload of 40 cc. Severe cardiac failure was induced with high dosages of esmolol. Measured parameters were aortic pressure (PA) and flow (QA), coronary flow (QC), and left ventricular pressure (PLV). Tension time index (TTI), total QA and QC, and end-diastolic aortic pressure (EDP) were computed to compare the efficacy of counterpulsation between assisted and unassisted conditions. Three conditions of inflation/deflation timing were examined: Normal timing (NT), early inflation (EI), and late deflation (LD). Results indicated that extraaortic counterpulsation device actuation yielded statistically significant increases in QC, and significant decreases in EDP and TTI for all timing conditions examined, when compared with unassisted conditions. Flow was significantly increased only for EI and NT timing conditions. Counterpulsation delivered with IABP yielded statistically significant increases in EDP for LD timing, and significant decreases in TTI for NT only. These results indicate that EACD is much less dependent on inflation/deflation timing when compared with IABP. The extraaortic counterpulsation device consistently increases QC and decreases TTI, which enhances the oxygen supply/consumption ratio (S/C) of the left ventricle. The intraaortic balloon pump does not significantly increase S/C in severe cardiac failure, and will increase afterload if deflation timing is not properly set.

Animals↗

PubMedDate not supplied

Pulmonary artery counterpulsation with a skeletal muscle power source.

We evaluated the feasibility of using skeletal muscle (SM) to provide pulmonary artery (PA) counterpulsation in an acute pulmonary hypertension (PHT) model. PA counterpulsation was achieved in six dogs with a dual chambered pump powered by the latissimus dorsi muscle. A rate-responsive stimulator was used to make the muscle contract in counterpulsation. Graded PHT was induced by infusing 150 microns glass beads into the PA, while RV and PA pressures were monitored. With PA pressures ranging from 19/10 to 115/62 mmHg, effective counterpulsation was observed. The degree of counterpulsation was influenced by the extent of PHT induced, with the amount of RV tension-time index (TTI) unloading correlated with the level of PA systole (r = 0.92). Therefore, results were divided into two groups (Group 1: PA systole less than or equal to 40 mmHg, and Group 2: PA systole greater than 40 mmHg). In Group 1, RV TTI decreased from 11.29 +/- 0.76 to 9.99 +/- 0.72 mmHg.sec, PA diastole increased from 20 +/- 2.3 to 31 +/- 3.0 mmHg, and PA mean increased from 24 +/- 2.2 to 2.9 +/- 2.2 mmHg (all p less than 0.05). In Group 2, RV TT1 decreased from 15.12 +/- 1.83 to 10.99 +/- 0.90 mmHg.sec, PA diastole increased from 41 +/- 3.5 to 64 +/- 6.2 mmHg, and PA mean increased from 49 +/- 4.8 to 55 +/- 5.7 mmHg (all p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Pulmonary artery balloon counterpulsation for right ventricular failure after right ventriculotomy in the swine.

To assess the efficacy of intrapulmonary balloon counterpulsation in the management of right ventricular failure after right ventriculotomy, we undertook an experimental study in a swine model. To mimic the clinical settings more closely, (1) we left the automatic control of the heart intact (2) did not use cardiopulmonary bypass to support the left side of the heart, and (3) induced right ventricular failure by means of a generous surgical incision (50% to 70% of the anterior wall) of the right ventricle. The criteria set for right ventricular failure were (1) 50% increase in right ventricular end-diastolic pressure, (2) 30% decrease in mean arterial pressure, and (3) 30% decrease in cardiac output. Right ventricular failure was attained in all animals studied: A 230% increase in right ventricular end-diastolic pressure, a 43% decrease in cardiac output, and a 34% decrease in mean arterial pressure were evident after the right ventriculotomy. A specially designed intrapulmonary balloon catheter (Datascope Corp., Oakland, N.J.) was placed into the left pulmonary artery through the right ventricular outflow tract. A Datascope console was used for counterpulsation. Effects of counterpulsation for 40 minutes in a 1:1 mode were assessed after surgical induction of right ventricular failure in 14 swine. Each animal served as its own control. The mean hemodynamic changes are outlined: Right ventricular end-diastolic pressure decreased by 48.9% (p = 0.01). Mean arterial pressure increased by 68.8% (p = 0.01) and cardiac output by 44.2% (p = 0.01). Histologic studies disclosed no morphologic damage to the pulmonary artery or valve in the specimens analyzed. In addition, these results were compared with those in a second group of seven swine in which right ventricular failure was induced by right ventriculotomy and a balloon was placed into the left pulmonary artery but not activated. These results of short-term counterpulsation should be evaluated in a longer term model so as to mimic more closely the clinical setting. If the hemodynamic benefits are duplicated, intrapulmonary balloon counterpulsation should be considered as a simple, effective device when right ventricular failure develops after right ventriculotomy. It effectively improves right ventricular function without damaging the pulmonary artery or valve.

Animals↗

PubMed1976

Effect of hypertonic mannitol and intraaortic counterpulsation on regional myocardial blood flow and ventricular performance in dogs during myocardial ischemia.

Studies were performed to determine if intervention with hypertonic mannitol and intraaortic balloon counterpulsation increases regional myocardial blood flow during acute myocardial ischemia. Anesthetized dogs on right heart bypass were studied. Heart rate was kept constant by atrial pacing. Myocardial ischemia was provided by ligating the proximal left anterior descending coronary artery for 12 minute periods. Infusion of hypertonic mannitol begun immediately after ligation increased coronary blood flow to the ischemic area by 36 +/- 9.0% (standard error) (P less than 0.01) and to the nonischemic left ventricle by 21 +/- 8.8% (P less than 0.05) as compared with flow in the same regions during the control coronary ligation. Intraaortic balloon counterpulsation begun immediately after ligation increased regional coronary flow to the ischemic region by 20 +/- 8.4% (P less than 0.05) but did not significantly alter flow to the nonischemic left ventricle as compared with levels during the control ligation. Combined intraaortic counterpulsation and hypertonic mannitol increased coronary flow to the ischemic region by 46 +/- 13% (P less than 0.02) and to the nonischemic left ventricle by 59 +/- 22% (P less than 0.05) as compared with flow during occlusion of the left anterior descending artery with mannitol alone. The data demonstrate that both hypertonic mannitol and intraaortic counterpulsation increase left ventricular ischemic regional flow and that combined hypertonic mannitol and intraaortic balloon counterpulsation provide a greater increase in regional coronary blood flow to both the ischemic and nonischemic regions of the left ventricle than mannitol alone.

Acute Disease↗

PubMed1975

Intra-aortic balloon counterpulsation: potential for therapy in hemorrhagic shock with associated myocardial failure.

After attaching appropriate monitoring devices enabling the measurement of the slope of the left ventricular function curve, left atrial pressure, mean aortic pressure, peak left ventricular pressure, and tension time index, three groups of ten dogs were subjected to varying periods of hemorrhagic shock until a slope of their ventricular function curve was reduced to either 75% (Group I), 50% (Group II), or 25% (Group III) of their baseline value. Resuscitation was attempted in all dogs by the intravenous infusion of shed blood plus additional balanced salt solution. This infusate was administered to maintain either the mean aortic pressure within 15 mm Hg of the baseline value or a left atrial pressure of 15 mm Hg, whichever occurred forst. One half of the dogs received, in addition, intra-aortic balloon counterpulsation. All dogs not receiving counterpulsation expired within two hours. There was no apparent effect of counterpulsation on Group I animals. Three of five animals (Group II) and four of five animals (Group III) receiving counterpulsation survived to the end of the experiment with significant (p smaller than .01) improvement in the parameters monitored. The utilization of counterpulsation as an adjunct to treatment in hemorrhagic shock is suggested.

Animals↗

PubMed1979

Arterial counterpulsation in severe refractory heart failure complicating acute myocardial infarction.

The role of arterial counterpulsation was sought in 100 patients with severe refractory cardiac failure complicating myocardial infarction. Seventy-four were in shock and 26 were not. Average duration of counterpulsation was 7.0 days. Hospital survival was 34 per cent (25/74) in shock (predicted less than 10%) and 65 per cent in patients who were not in shock (predicted less than 50%). Survival at 4 years was 10 +/- 4 per cent in shock and 37 +/- 11 per cent in patients not in shock; functional status was class 1 or 2 in 5 of 9 patients in shock and in 8 of 12 survivors not in shock. Results were best when counterpulsation was started early after onset of symptoms, when ischaemic pain was still present, or when a mechanical defect was corrected surgically. Early coronary artery bypass surgery performed alone in 9 patients did not influence survival or functional status. Complications of counterpulsation occurred in 17 patients in shock and in 2 patients not in shock, all but 6 on the first day; none directly caused death. Counterpulsation is an effective and safe adjunct to medical treatment of complicated infarction provided the intervention is prompt.

Adult↗

PubMed1989

Pulmonary artery counterpulsation to improve right ventricular function after heart transplantation.

The effectiveness of pulmonary artery counterpulsation in improving right ventricular function after heart transplantation was evaluated in a pig model. The balloon catheter was introduced through the anterior wall of the pulmonary artery distal to the pulmonary valve. A Millar catheter with a distal high-fidelity pressure transducer was placed in the right ventricle, where the peak rate of pressure rise, dP/dT, was measured. Pulmonary artery counterpulsation significantly improved right ventricular function, increasing both dP/dT and systolic pressure. A diastolic dip in pulmonary artery pressure and a fall in the early portion of the right ventricular pressure curve were seen. Inflation of the balloon caused a second (suprasystolic) wave in that curve. Improved right ventricular function was also seen when normal pig hearts were counterpulsated after occlusion of the right coronary artery and following increased afterload due to occlusion of a main pulmonary artery. There were no changes in central venous or systemic pressure. The results indicate that pulmonary artery counterpulsation may be valuable when the transplanted heart has a poorly functioning right ventricle.

Animals↗