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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

Juxtaaortic counterpulsation: comparison with intraaortic counterpulsation in an animal model of acute heart failure.

This study was designed to compare the effects of juxtaaortic balloon counterpulsation (JABC), performed in ascending aorta and the aortic arch, with those yielded by intraaortic balloon counterpulsation (IABC) in descending aorta, in experimental animals during induced cardiac failure. JABC was achieved with a manufactured Dacron prosthesis and a balloon pump placed between the prosthesis and the wrapped aorta. JABC resulted in a significant increase of cardiac output (from 2.33+/-0.82 to 2.61+/-1.12 L/min, p < 0.05), cardiac index (from 0.071+/-0.025 to 0.080+/-0.033 L/min/kg, p < 0.05) and diastolic pressure augmentation evaluated through diastolic and systolic areas beneath the aortic pressure curve (DABAC/SABAC) index (from 0.94+/-0.21 to 1.10+/-0.33, p < 0.01). End diastolic aortic pressure showed a significant decrease with JABC (from 31.90+/-7.09 to 27.83+/-9.72 mm Hg, p < 0.05). A close association between percentage of DABAC/SABAC increases obtained with IABC and JABC was observed (r2 = 0.67; p < 0.001). Counterpulsation obtained by a juxtaaortic catheter placed in the arch and the ascending wrapped aorta results in an effective hemodynamic improvement comparable with that achieved by an intraaortic catheter in open chest sheep.

Animals↗
PubMed2002

Effects of enhanced external counterpulsation on Health-Related Quality of Life continue 12 months after treatment: a substudy of the Multicenter Study of Enhanced External Counterpulsation.

BACKGROUND: The Multicenter Study of Enhanced External Counterpulsation (MUST-EECP) was the first prospective, randomized, blinded, sham-controlled study of enhanced external counterpulsation (EECP) in the treatment of chronic stable angina. We previously reported that EECP therapy lengthens the time to exercise-induced myocardial ischemia and reduces angina. We now describe the effects of EECP therapy versus a sham-treated control group in terms of patients' functioning, their senses of well-being and other Health-Related Quality Of Life (HQOL) parameters from baseline to end of treatment and from baseline to 12 months after treatment. OBJECTIVE: To determine whether a 35-hour course of EECP affects the HQOL of patients with symptomatic coronary artery disease, 12 months following treatment. METHODS: Seventy-one of the 139 patients enrolled in MUST-EECP provided evaluable patient-completed questionnaires at baseline, at the end of treatment, and 12 months post-treatment. The Medical Outcomes Study 36-Item Short-Form Health Survey and the Quality of Life Index-Cardiac Version III were used to assess effects on HQOL. RESULTS: Both groups had similar HQOL scores at baseline. At end of treatment and at 12-month follow up, patients who had active-CP reported greater improvement than those who had inactive-CP in all nine quality of life scales, including ability to perform activities of daily living, ability to work, bodily pain, confidence in health, energy, ability to engage in social activities with family and friends, anxiety and depression, and quality of life issues from the effects of angina on health and functioning. Despite small sample sizes, active-CP patients demonstrated significantly greater improvement at 12 months following treatment in bodily pain, social functioning, and quality of life specific to cardiac patients compared with inactive-CP patients. CONCLUSION: Significant health-related quality of life improvements were measurable up to 12 months after the completion of treatment with EECP. Improvements in this controlled study are consistent with HQOL changes reported in case series and patient registries. Larger studies are warranted.

Aged↗
PubMedDate not supplied

New graduated pressure regimen for external counterpulsation reduces mortality and improves outcomes in congestive heart failure: a report from the Cardiomedics External Counterpulsation Patient Registry.

External counterpulsation (ECP) has been shown to increase exercise tolerance and reduce angina episodes, Canadian Cardiovascular Society Functional (CCSF) class, anginal medication usage, and hospitalizations in refractive CCSF class III and IV stable angina. However, the high pressures and resulting 1.5:1-2:1 peak diastolic to peak systolic pressure (D/S) ratios shown to be optimal in the treatment of angina can cause excessive preload and adverse effects in congestive heart failure (CHF) patients, particularly those with left ventricular ejection fractions <40%. Data were retrospectively analyzed from the Cardiomedics ECP Registry on 127 New York Heart Association (NYHA) class II-IV CHF patients (79.6% men; average age +/- SD, 68.2+/-15.6 years), with a comorbidity of CCSF class III-IV refractive angina, who were serially treated with 35 hours of ECP (1 h/d, 5 d/wk for 7 weeks) at unconventionally low pressures and D/S ratios under a new graduated pressure regimen. The pressures and D/S ratios were gradually increased in stages over the 7-week ECP regimen. The patients were divided into three groups based on the pressures applied and the resulting average D/S ratios (Low, Mid, and High). In the Low D/S ratio group (average D/S ratio 0.7:1), all-cause mortality in the year following ECP treatment was only 1.85% (one of 54 patients), whereas over the same time period in the Mid D/S ratio group (average D/S ratio 1.08:1), all-cause mortality was 7.69% (three of 39 patients) and in the High D/S ratio group (average D/S ratio 1.32:1), all-cause mortality was 8.82% (three of 34 patients). For the Low, Mid, and High D/S ratio groups, respectively: 1) average left ventricular ejection fractions increased 23.0%, 20.1%, and 17.5%; 2) NYHA class declined 36.6%, 29.6%, and 29.6%; and 3) all-cause hospitalizations, including terminal admissions, were reduced 85.7%, 82.6%, and 57.1% in the year following ECP therapy from the prior year. There were no adverse effects or withdrawals from the ECP therapy and no significant difference in sex-based outcomes. Consequently, ECP applied at low pressures and average D/S ratios of 0.7:1 under the new graduated pressure regimen is safe and effective in the treatment of CHF and produces a significant reduction in mortality, compared with the 8.5% annualized mortality of the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) (N=1232) of NYHA class II-III CHF and the 12.2% annual mortality of the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) study (N=595) of NYHA class III-IV CHF. Lower pressures improve patient comfort and may encourage more CHF patients to seek treatment. The reduction in hospitalizations should significantly reduce the cost of treating CHF.

Aged↗
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↗
PubMed1994

Use of aortic counterpulsation to improve sustained coronary artery patency during acute myocardial infarction. Results of a randomized trial. The Randomized IABP Study Group.

BACKGROUND: Aortic counterpulsation has been observed to reduce the rate of reocclusion of the infarct-related artery after patency has been restored during acute myocardial infarction in observational studies. To evaluate the benefit-to-risk ratio of aortic counterpulsation during the early phase of myocardial infarction, a multicenter randomized clinical trial was performed. METHODS AND RESULTS: Patients who had patency restored during acute cardiac catheterization within the first 24 hours of onset of myocardial infarction were randomly assigned to aortic counterpulsation for 48 hours versus standard care. Intravenous heparin was used similarly in both groups and was continued for a median (25th, 75th percentile) of 5 (2,7) days. A total of 182 patients were enrolled; 96 were assigned to aortic counterpulsation and 86 to standard care. Repeat cardiac catheterization was performed at a median of 5 (4,6) days after randomization in 89% of patients assigned to aortic counterpulsation and in 90% of control patients. Patients randomized to aortic counterpulsation had similar rates of severe bleeding complications (2% versus 1%), number of units of blood transfused (mean, 1.3 +/- 2.6 versus 0.9 +/- 1.8 units), and vascular repair or thrombectomy (5% versus 2%) compared with patients treated in a conventional manner. Patients randomized to aortic counterpulsation had significantly less reocclusion of the infarct-related artery during follow-up compared with control patients (8% versus 21%, P < .03). In addition, there was a significantly lower event rate in patients assigned to aortic counterpulsation in terms of a composite clinical end point (death, stroke, reinfarction, need for emergency revascularization with angioplasty or bypass surgery, or recurrent ischemia): 13% versus 24%, P < .04. CONCLUSIONS: This randomized trial showed that careful use of prophylactic aortic counterpulsation can prevent reocclusion of the infarct-related artery and improve overall clinical outcome in patients undergoing acute cardiac catheterization during myocardial infarction.

Angioplasty, Balloon, Coronary↗
PubMed1981

Randomized controlled trial of intraaortic balloon counterpulsation in early myocardial infarction with acute heart failure.

The value of intraaortic balloon counterpulsation in limiting infarct size and improving survival was studied in patients with early transmural myocardial infarction complicated by acute heart failure. Thirty such patients, previously well, were randomly assigned to counterpulsation (14 patients) or standard therapy (16 patients). Counterpulsation was begun 4.8 to 13.7 hours (mean 7.1) after the onset of pain and continued for less than 1 to 11 days (mean 4.5). Peak creatine kinase was 1,794 +/- 846 IU/liter (mean +/- standard deviation) in patients receiving counterpulsation compared with 1,688 +/- 908 for those receiving standard therapy; cumulative creatine kinase was 3,590 +/- 1,936 IU/liter for patients receiving counterpulsation and 2,945 +/- 1,803 for those receiving standard therapy. Hospital mortality was similar (counterpulsation, 7 of 14; standard therapy, 7 of 16 [p = 0.05 for 25 percent mortality reduction]) as was mortality at follow-up (counterpulsation, 8 of 14; standard therapy, 10 of 16 [p = 0.09 for 25 percent mortality reduction]). Functional class at follow-up examination 1 to 36 months (mean 15) after infarction was also similar in the two groups. Counterpulsation did not appear to modify infarct size or to alter morbidity or mortality when initiated as primary therapy 4.8 to 13.7 hours after the onset of symptoms of myocardial infarction.

Acute Disease↗
PubMed1994

Intraaortic balloon counterpulsation enhances coronary thrombolysis induced by intravenous administration of a thrombolytic agent.

OBJECTIVES: This study was designed to test the hypothesis that in the presence of moderate hypotension, intraaortic balloon counterpulsation would enhance coronary thrombolysis induced by intravenous administration of recombinant tissue-type plasminogen activator (rt-PA). BACKGROUND: Although many studies have confirmed the efficacy of thrombolytic therapy in acute myocardial infarction, few have systematically investigated the effects of alterations in aortic pressure on coronary thrombolysis, and none have previously investigated the effects of intraaortic balloon counterpulsation on thrombolysis. METHODS: The effects of intraaortic balloon counterpulsation on aortic pressure, coronary blood flow and coronary thrombolysis were studied in a canine model. Coronary thrombosis was induced in eight dogs by injection of radioactive blood clot through a catheter placed in the left anterior descending coronary artery. Subsequently, dogs underwent phlebotomy to decrease systolic aortic pressure to approximately 90 mm Hg. After phlebotomy, during a 15-min interval of intravenous administration of rt-PA, coronary thrombolysis and coronary flow were determined during and in the absence of counterpulsation. RESULTS: Intraaortic balloon counterpulsation significantly increased aortic diastolic pressure. Corresponding to the increase in pressure, intraaortic balloon counterpulsation significantly increased the rate of rt-PA-induced coronary thrombolysis. Although not statistically significant, peak diastolic coronary flow tended to increase with counterpulsation. CONCLUSIONS: These results indicate that in the presence of moderate systemic hypotension, intraaortic balloon counterpulsation enhances the rate of rt-PA-induced coronary thrombolysis.

Animals↗
PubMed1998

Complications of intra-aortic balloon counterpulsation. The role of catheter size and duration of support in a multivariate analysis of risk.

AIMS: The aim of this study was to assess the risk of intra-aortic balloon counterpulsation and to identify clinical and procedural variables that would predict complications. METHODS AND RESULTS: We analysed 381 consecutive patients who were treated between 1977 and 1995 at our catheterization laboratory and/or medical intensive care unit. The complications considered relevant were limb ischaemia requiring catheter removal, vascular injury, bleeding requiring transfusion, embolic events, and infection. In eight patients the balloon could not be inserted. The rate of complications for the remaining 373 patients was 12.9%. Between 1977 and 1980, surgical insertion was performed using a 12 French catheter with a complication rate of 30.4% (seven of 23 patients). Percutaneous implantation, performed after 1981, had an overall complication rate of 11.7% (41 of 350 patients). Using thinner catheters for percutaneous placement was associated with a reduction in the rate of complications, from 20.7% (17 of 82 patients) for 12 French catheters to 9.9% (10 of 101 patients) for 10.5 French catheters (P = 0.04), and 8.4% (14 of 167 patients) for 9.5 French catheters (P = 0.006). Multivariate logistic regression analysis identified duration of counterpulsation > 48 h (odds ratio 3.6), catheter size (odds ratio 3.4 for 12 French catheters), peripheral vascular disease (odds ratio 2.7), and shock (odds ratio 2.0) as independent risk factors for counterpulsation-associated complications. When considering 9.5 French catheters only (167 patients, all after 1992), the sole remaining independent risk factor was duration of counterpulsation > 48 h (odds ratio 3.8). Those patients with 9.5 French catheters in whom counterpulsation did not exceed 48 h had a low complication rate of 3.9%. CONCLUSION: The rate of percutaneous intra-aortic balloon counterpulsation complications was thus significantly reduced by employing thinner catheters. It was at an acceptable level for 9.5 French catheters, where a long duration of counterpulsation emerged as the most significant factor associated with complications. Whether using even thinner catheters in combination with a sheathless implantation technique further minimizes the risk of counterpulsation remains to be seen.

Aged↗
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↗
PubMed1999

Dynamic abdominal and thoracic aortomyoplasty in heart failure: assessment of counterpulsation.

BACKGROUND: Aortic counterpulsation, either biologic or mechanical, is a useful technique to support circulation during left ventricular dysfunction. METHODS: In this study we used an induced cardiac failure model in acute open chest sheep to compare hemodynamic improvements between thoracic and abdominal aortic counterpulsation. This was achieved with left latissimus dorsi and left hemidiaphragm muscle flaps. RESULTS: Thoracic and abdominal aortic counterpulsation in heart failure resulted in a significant improvement of hemodynamic parameters. Subendocardial viability index, defined as diastolic pressure-time index to systolic tension-time index, in thoracic and abdominal aortomyoplasty showed significant improvement (p<0.05) when cardiac assistance was performed by electrical stimulation of each muscle flap. A new counterpulsation index derived from diastolic and systolic areas beneath the aortic pressure curve was tested, obtaining a correlation coefficient with the subendocardial viability index of 0.758 (p<0.001). Values of subendocardial viability index and counterpulsation index showed minimal variability. CONCLUSIONS: Treatment of experimentally induced cardiac failure with dynamic abdominal aortic counterpulsation allows an effective hemodynamic improvement in open chest sheep. Furthermore, this diastolic arterial pressure augmentation could be evaluated through a new counterpulsation index derived from diastolic and systolic areas beneath the aortic pressure curve.

Animals↗
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↗
PubMedDate not supplied

Enhanced external counterpulsation in patients with heart failure: a multicenter feasibility study.

To assess the feasibility of using enhanced external counterpulsation to treat patients with heart failure, 26 patients with stable heart failure (New York Heart Association classes II-III), with a left ventricular ejection fraction at or below 35%, and without fluid overload, were treated with enhanced external counterpulsation (1 hour daily, 5 days a week, to a total of 35 hours). Patients were followed for 6 months after completing the course of enhanced external counterpulsation. The primary parameter was safety as reflected by adverse events or by changes in laboratory parameters. Secondary end points included changes in exercise capacity and quality of life. There were no clinically significant problems associated with the administration of enhanced external counterpulsation. Significant improvements were seen in exercise capacity (peak oxygen uptake and exercise duration), and in quality of life assessments, at 1 week and 6 months after the course of enhanced external counterpulsation. This study suggests that enhanced external counterpulsation is safe and well tolerated in patients with stable heart failure, and that a randomized, controlled study of enhanced external counterpulsation in these patients is warranted.

Adult↗
PubMed2004

Impact of intraaortic balloon counterpulsation on arterial blood flow in juvenile pigs with heart failure.

OBJECTIVES: To assess the impact of intraaortic balloon counterpulsation on coronary, renal and aortic blood flow in an animal heart failure model. BACKGROUND: Heart failure exacerbations are still often treated with inotropic medications despite a lack of evidence demonstrating any benefit with these drugs. Intraaortic balloon counterpulsation may be considered in certain cases a bridge to recovery. METHODS: Four juvenile pigs underwent pacemaker implantation to induce a rapid-pacing mediated dilated cardiomyopathy. After approximately 4 weeks of rapid pacing, the mean ejection fraction was reduced to 28.8+/-9.5% with a mean systolic blood pressure of 64/44 mmHg. The pigs then underwent surgical placement of flow probes around the circumflex coronary artery, renal artery and infrarenal aorta. A Millar catheter was used to calculate Dp/Dt and a Swan-Ganz to calculate cardiac output. Data were recorded at baseline and after 10 minutes of balloon pumping. The pigs were euthanized post-procedure. RESULTS: Coronary blood flow was increased 9.7% by balloon counterpulsation from 38.3 +/- 12.0 to 42.0+/-11.4 ml/s (p=NS). Renal blood flow was reduced 11.9% by counterpulsation from 130.0+/-88.6 ml/s to 114.5+/-76.6 ml/s (p=NS). Infrarenal aortic blood flow was not changed (mean of 900 ml/s with and without counterpulsation); blood pressure, cardiac output and Dp/Dt were not changed after 10 minutes of pumping. There was little impact observed by changing the position of the balloon closer to or farther away from the apex of the aortic arch. CONCLUSION: Intraaortic balloon counterpulsation did not significantly improve hemodynamics in the pig heart failure model. This may be attributed to the high compliance of the juvenile pig's aorta, thus attenuating the pressure wave generated by counterpulsation. A larger volume balloon would merit investigation for this application.

Animals↗
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↗
PubMed1993

Pulmonary artery balloon counterpulsation: safe after peripheral placement.

Pulmonary artery balloon counterpulsation is a promising experimental technique for treatment of right ventricular failure. However, clinical application has been limited in that the only device presently available (the large-volume intraaortic balloon) must be placed within a synthetic graft. Because a balloon with a smaller volume (which could be placed through a peripheral vein and be contained entirely within the pulmonary artery) would make the technique feasible on a wider scale, we tested an 8-mL pulmonary artery balloon placed through the femoral vein in 12 dogs. Two groups of animals were compared. One group had the pulmonary artery balloon in place but not counterpulsating; the other had the pulmonary artery balloon in place and counterpulsating. Each group was studied for 12 hours. A variety of hemodynamic parameters were measured. Effective diastolic augmentation and systolic unloading were noted in all 6 dogs that underwent counterpulsation (5.0 +/- 1.1 mm Hg of diastolic augmentation and 9.5 +/- 1.6 mm Hg of systolic unloading). Pulmonary function, as measured by arterial blood gas sampling and pulmonary vascular resistance, was not impaired. Examination of the heart and lungs showed no detrimental pathologic effects of pulmonary artery balloon counterpulsation. Placement of the balloon through a peripheral vein with a guidewire was easy and uncomplicated. We conclude that pulmonary artery balloon counterpulsation is safe over an extended period of 12 hours in the canine model and that diastolic augmentation and systolic unloading can be produced.

Animals↗