Intraaortic balloon counterpulsation: its influence alone and combined with various pharmacological agents on regional myocardial blood flow during experimental acute coronary occlusion

Review article : Mechanical ventricular support in the management of postcardiotomy cardiogenic shock

'For many reasons clinicians hesitate to employ mechanical devices of unproved efficacy except in the most critically ill patients and then only as a desperate measure. These approaches accounted for a substantial lag time between intra-aortic balloon pump availability and widespread utilization. Ventricular assist devices, recently approved for initial clinical trials, face the same dilemmas'. Norman, 1977.1

Intra-aortic balloon counterpulsation

Intra-aortic balloon counterpulsation (IABP) is sometimes used in critically ill patients with cardiac disease. By increasing diastolic arterial pressure and decreasing systolic pressure, it reduces left ventricular afterload. IABP may be beneficial in subjects with cardiogenic shock, mechanical complications of myocardial infarction, intractable ventricular arrhythmias, or advanced heart failure or those who undergo "high-risk" surgical or percutaneous revascularization, but the evidence to support its use in these patient groups is largely observational. Contraindications to IABP include severe peripheral vascular disease as well as aortic regurgitation, dissection, or aneurysm. The potential benefits of IABP must be weighed against its possible complications (bleeding, systemic thromboembolism, limb ischemia, and, rarely, death).

Treatment of post resuscitation myocardial dysfunction: aortic counterpulsation versus dobutamine

BACKGROUND

Post resuscitation myocardial stunning is well described and recognized as a significant contributor to poor long-term outcome following cardiac arrest. Optimal strategies for treatment have not been determined.

METHODS

Ten domestic swine (49+/-3 kg) underwent 15 min of untreated ventricular fibrillation before being successfully resuscitated. Left ventricular systolic and diastolic function was measured at pre-arrest baseline, at 30 min and at 6 h post resuscitation. Five animals were treated immediately after resuscitation with intra-aortic balloon counterpulsation (IABP) and five were given dobutamine (5 mcg/kg per min).

RESULTS

No baseline differences were found. At 30 min post resuscitation pulmonary capillary wedge pressure and LVEDP were significantly higher (16+/-3 vs. 7+/-1 and 20+/-2 vs. 11+/-1 mmHg) while LV isovolumic relaxation ('Tau') was significantly longer (34+/-2 vs. 20+/-2 ms) in the IABP treated versus the dobutamine treated animals. Likewise, at 6 h post resuscitation LV ejection fraction was significantly less (21+/-6 vs. 39+/-4%), and LVEDP significantly higher (18 vs. 10 mmHg) in the IABP group. Heart rate was not different between the groups at any time post resuscitation.

CONCLUSION

Dobutamine was superior to IABP for treatment of post resuscitation left ventricular systolic and diastolic dysfunction. The hypothesized advantage of IABP for treatment of post resuscitation myocardial stunning without excessively raising the heart rate like dobutamine was not realized.

Hemodynamic evaluation of descending aortomyoplasty versus intra-aortic balloon pump performed in normal animals: an acute study

OBJECTIVE

Aortomyoplasty is a surgical procedure that aims to induce hemodynamic benefits similar to those of the intra-aortic-balloon-pump (IABP). The objective of this study was to compare the coronary blood flow augmentation and afterload reduction produced by IABP and descending aortomyoplasty counterpulsation.

METHODS

From a series of fifteen mongrel dogs (18-35 kg), eight underwent acute descending aortomyoplasty and seven had IABP application. Left anterior descending (LAD) coronary artery blood flow was measured using a Doppler flow probe. Left ventricular pressure in addition to aortic pressures both proximal and distal to either the aortomyoplasty site or the IABP position were monitored continuously. All experiments were acute and performed in normal hearts.

RESULTS

Descending aortomyoplasty induced a 27% increase in the LAD blood flow integral during assisted beats (14.0+/-6 ml/min integral compared to 10.8+/-4 ml/min integral in unassisted beats [P<0.001]). This was comparable to an 18% rise in the LAD blood flow integral during IABP counterpulsation (from 8.6+/-3 ml/min to 10.2+/-4 ml/min [P<0.001]). Conversely, while IABP counterpulsation reduced the left ventricular afterload by 16% (from 102+/-23 mmHg to 86+/-26 mmHg [P<0.001]), descending aortomyoplasty did not result in afterload reduction.

CONCLUSIONS

Descending aortomyoplasty produces coronary blood flow augmentation comparable to that achieved by the IABP. This may be important for end-stage ischemic patients. However, afterload reduction achieved by the IABP was not reproduced during descending aortomyoplasty counterpulsation. The surgical technique of descending aortomyoplasty should be modified to attain afterload reduction, thus improving treatment for congestive heart failure patients.

Relation of hemodynamic variables to augmentation of left anterior descending coronary flow by intraaortic balloon pulsation in coronary artery disease

Recent studies suggest prophylactic intraaortic balloon-pulsation (IABP) in patients undergoing coronary reperfusion therapy. However, variable effects of IABP on coronary blood flow are reported. It is suggested that augmentation of coronary flow is more effective in patients with a compromised hemodynamic status, which might have potential relevance in selecting IABP treatment in patients undergoing reperfusion therapy.

Effects of intraaortic balloon pumping on septal arterial blood flow velocity waveform during severe left main coronary artery stenosis

OBJECTIVES

We sought to evaluate the effect of intraaortic balloon pumping on the phasic blood velocity waveform into myocardium with severe coronary artery stenosis.

BACKGROUND

In the presence of severe coronary artery stenosis, it is not clear whether intraaortic balloon pumping augments intramyocardial inflow during diastole or changes systolic retrograde blood flow from the myocardium to the extramural coronary arteries.

METHODS

Using anesthetized open chest dogs (n=7), we introduced severe stenosis in the left main coronary artery to reduce the poststenotic pressure to approximately 60 mm Hg (>90% diameter stenosis). Septal arterial blood flow velocities were measured with a 20-MHz, 80-channel ultrasound pulsed Doppler velocimeter. Left anterior descending arterial flow, aortic pressure and poststenotic distal coronary pressure were measured simultaneously. The diastolic anterograde flow integral and systolic retrograde flow integral were compared in the presence and absence of intraaortic balloon pumping.

RESULTS

Although intraaortic balloon pumping augmented diastolic aortic pressure, this pressure increase was not effectively transmitted through stenosis. Septal arterial diastolic flow velocity was not augmented, and left anterior descending arterial flow was unchanged during intraaortic balloon pumping.

CONCLUSIONS

In the presence of severe coronary artery stenosis, intraaortic balloon pumping failed to increase diastolic inflow in the myocardium and did not enhance systolic retrograde flow from the myocardium to the extramural coronary artery. Thus, the major effect of intraaortic balloon pumping on the ischemic heart with severe coronary artery stenosis may be achieved by reducing oxygen demand by systolic unloading.

Improved efficacy of intra-aortic balloon pumping by pharmacological myocardial protection for postoperative pump failure after coronary revascularization

Fifty patients took part in a randomized and prospective study to define the effect of pharmacological myocardial protection when using IABP in patients with postoperative pump failure, following coronary revascularization under cardiopulmonary bypass employing moderate hypothermia and cardioplegia. Pharmacological protection was given to 23 patients, administering coenzyme Q, 5 mg/kg, and aprotinin, 10,000 KIU/kg, intravenously, every 12 hours, following surgery. A single dose of each drug was also given intraoperatively. The postoperative haemodynamics, serum enzyme levels and success of weaning from IABP, were compared between the group of patients who received pharmacological protection (the treated group) and the control group which comprised 27 patients who were treated only with IABP. Among the surviving patients, no significant differences were seen in the hemodynamics or cardiac enzyme levels between the two groups. The rate of successful weaning from IABP however, was 95 per cent in the treated group as compared with only 74 per cent in the control group, p = 0.02. These results suggest that pharmacological myocardial protection, using coenzyme Q and aprotinin in both the intra- and post-operative periods, improves the efficacy of IABP in the treatment of post-operative pump failure following coronary revascularization.

Combined treatment of coenzyme Q10 and aprotinin with intraaortic balloon pumping following aorto-coronary bypass surgery

The effect of combined treatment of coenzyme Q10 (CoQ10) and aprotinin with intra-aortic balloon pumping (IABP) was evaluated in patients who underwent aorto-coronary bypass surgery. Forty-one patients were divided into two groups. Group A (27) were treated by IABP only and Group B (14) were treated by the concomitant use of CoQ10 and aprotinin with IABP. Both groups were subdivided into two groups with regard to the ability to be weaned from IABP (Group A-I, Group B-I) or the inability (Group A-II, Group B-II). CoQ10 was administrated intravenously at doses of 5-10 mg/kg/day and aprotinin was infused at doses 5,000-10,000 KU/kg/day. The percentile incidence of ability to be weaned from IABP was 93 per cent (13/14) in Group B was higher than that of 74 per cent (20/27) in Group A. There were no significant differences among Group A-I, Group A-II, and Group B-I with regard to preoperative and intraoperative factors. Serum GOT and CPK levels on the first postoperative day were significantly higher in Group A-II and Group B-I than those in Group A-I but there was no significant difference between GOT or CPK levels in Group A-II and Group B-I. These results suggest that concomitant treatment of CoQ10 and aprotinin with IABP leads to an improvement in postoperative low cardiac output syndrome.