Percutaneous mechanical circulatory support devices in high-risk patients undergoing percutaneous coronary intervention: A meta-analysis of randomized trials

BACKGROUND

Percutaneous mechanical circulatory support devices (pMCSDs) are increasingly used on the assumption (but without solid proof) that their use will improve prognosis. A meta-analysis was undertaken according to the PRISMA guidelines to evaluate the benefits of pMCSDs in patients undergoing high-risk percutaneous coronary intervention (hr-PCI).

METHODS

We searched PubMed, EMbase, Cochrane Library, Clinical Trial.gov, and other databases to identify eligible studies. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated for 30-day and 6-month all-cause mortality rates, reinfarction, and other adverse events using a random effect model.

RESULTS

Sixteen randomized controlled trials (RCTs) were included in this study. In the pooled analysis, intra-aortic balloon pump (IABP) was not associated with a decrease in 30-day and 6-month all-cause mortality (RR 1.01 95% CI 0.61-1.66; RR 0.88 95% CI 0.66-1.17), reinfarction (RR 0.89 95% CI 0.69-1.14), stroke/transient ischemic attack (TIA) (RR 1.75 95% CI 0.47-6.42), heart failure (HF) (RR 0.54 95% CI 0.11-2.66), repeat revascularization (RR 0.73 95% CI 0.25-2.10), embolization (RR 3.00 95% CI 0.13-71.61), or arrhythmia (RR 2.81 95% CI 0.30-26.11). Compared with IABP, left ventricular assist devices (LVADs) were not associated with a decrease in 30-day and 6-month all-cause mortality (RR 0.96 95% CI 0.71-1.29; RR 1.23 95% CI 0.88-1.72), reinfarction (RR 0.98 95% CI 0.68-1.42), stroke/TIA (RR 0.45 95% CI 0.1-1.95), acute kidney injury (AKI) (RR 0.83 95% CI 0.38-1.80), or arrhythmia (RR 1.52 95% CI 0.71-3.27), but LVADs were associated with a decrease in repeat revascularization (RR 0.26 95% CI 0.08-0.83). However, LVADs significantly increased the risk of bleeding compared with IABP (RR 2.85 95% CI 1.72-4.73).

CONCLUSIONS

Neither LVADs nor IABP improves short or long-term survival in hr-PCI patients. LVADs are more likely to reduce repeat revascularization after PCI, but to increase the risk of bleeding events than IABP.

[Support of damaged heart with the Impella pump]

Temporary mechanical circulatory support is increasingly used, particularly in patients with cardiogenic shock or during high-risk percutaneous coronary interventions. In the last five years there have been numerous developments in this field. Experience has been gained from usage of temporary heart pumps, and new pumps have arrived on the market. Until recently, the intra-aortal balloon pump was the standard treatment for patients with cardiogenic shock; however, results from the latest research into the effectiveness of this pump have rendered it less popular. An alternative modality is the Impella system. Since 2012, usage of a heart pump in cardiogenic shock treatment is reimbursed by healthcare insurers in the Netherlands. Recently, the FDA approved the Impella system for said indication.

[The use of preoperative intra-aortic balloon in myocardial revascularization surgery associated to severe ventricular dysfunction]

OBJECTIVE

To evaluate the effectiveness of prophylactic intra-aortic balloon (IAB) in elective myocardial revascularization surgery (MRS), to prevent trans or post-operative infarction and reduce intra-hospital mortality in patients with low left ventricular ejection fraction.

METHODS

Using a cohort study model, 239 patients with left ventricular ejection fraction < or = 40%, submitted to elective MRS with extracorporeal circulation (ECC) were evaluated from March 1995 to February 2001.

RESULTS

Of these, 58 patients received preoperative IAB and the remainder underwent surgery without circulatory assistance (control group). The two groups of patients had similar characteristics regarding factors associated to the pertaining outcomes. There were five demises (8.6%) in the group with IAB and 21 (11.6%) in the control group (non-significant difference). There were 2 (3.4%) infarctions in the IAB group and 28 (15.5%) in the control group (p< 0.05), relative risk of 0.22 with an interval of confidence of 95% from 0.05 to 0.85.

CONCLUSION

The use of pre-operative IAB can significantly reduce the risk of trans or post-operative acute myocardial infarction (AMI) in patients with decreased systolic function, without increasing vascular complications. In this same situation, the IAB does not significantly decrease mortality. Randomized studies are necessary to establish more precise conclusions.

Routine preoperative insertion of IABP in high-risk off-pump coronary artery bypass grafting

The beneficial effects of intraaortic balloon pump (IABP) in coronary artery bypass graft surgery with cardiopulmonary bypass have been reported. However, whether preoperative insertion of IABP in high-risk off-pump coronary artery bypass grafting (OPCAB) has any beneficial effects remains to be established. We report our experience of preoperative insertion of IABP in OPCAB.

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.

[The effect and role of the intraaortic balloon pumping in off-pump coronary artery bypass]

Eighty consecutive patients who underwent off-pump coronary artery bypass (OPCAB) were studied. They were divided into group I (n = 10) which received preoperative intraaortic balloon pumping (IABP), and group II (n = 70) which did not receive IABP. The indications for preoperative IABP were severe left main coronary artery disease in 7 patients, severe 3 vessel disease in 3 patients, unstable angina in 5 patients, acute myocardial infarction in 3 patients. There was no operative mortality in both groups. The average number of distal anastomosis 2.7/patients in group I and 3.3/patients in group II. There was no differences in ventilator support time, length of stay in the intensive care unit and morbidity between 2 groups. The average postoperative IABP support time was 5.4 hours. There was no IABP-related complication in group I. IABP was very effective to perform OPCAB surgery safety. Preoperative IABP may be effective modality to support OPCAB surgery not only in emergent case but also in elective case.

Effect of intra-aortic occlusion balloon in external thoracic compressions during CPR in pigs

This study was performed to compare the effectiveness of external thoracic compressions with and without intra-aortic occlusion balloon with capnography and coronary and cerebral perfusion pressure (CPP) in the normothermic and traumatic-less cardiopulmonary arrest provoked by a ventricular fibrillation in pigs. This was an experimental study (cross-over study) in 14 pigs with similar characteristics (23 +/- 2 kg, 10-12 weeks of age). After an 8-minute nonintervention period, the cardiopulmonary resuscitation (CPR) consists of 4 periods of 5 minutes alternating CPR with and without intra-aortic occlusion balloon. Main outcomes measured are end-tidal CO(2) (ETCO(2)); intra-aortic, coronary, and cerebral perfusion pressures; blood gas analysis; and blood lactate concentration. At the end of each period, levels are obtained. Postmortem study was made. Inflation of the occlusion balloon provokes an expansion in the ETCO(2) of about 38%. The coronary perfusion pressure initially goes from 10.21 to 29.0 mm Hg after the occlusion of the aorta, which means an increase of 150%. The CPP goes from 12.54 to 39.71 mm Hg after the balloon was inflated, which means an increase of 200%. In all cases the differences are statistically significant (P <.0001). These increases are less important in the final periods. Intra-aortic balloon occlusion increased ETCO(2), coronary, and cerebral perfusion pressures. An early application of this technique was important.

The current practice of intra-aortic balloon counterpulsation: results from the Benchmark Registry

OBJECTIVES

This study presents clinical data from the first large registry of aortic counterpulsation, a computerized database that incorporates prospectively gathered data on indications for intra-aortic balloon counterpulsation (IABP) use, patient demographics, concomitant medication and in-hospital outcomes and complications.

BACKGROUND

The intra-aortic balloon pump (IABP) is widely used to provide circulatory support for patients experiencing hemodynamic instability due to myocardial infarction, cardiogenic shock, or in very high risk patients undergoing angioplasty or coronary artery bypass grafting.

METHODS

Between June 1996 and August 2000, 203 hospitals worldwide (90% U.S., 10% non-U.S.) collected 16,909 patient case records (68.8% men, 31.2% women; mean age 65.9 +/- 11.7 years).

RESULTS

The most frequent indications for use of IABP were as follows: to provide hemodynamic support during or after cardiac catheterization (20.6%), cardiogenic shock (18.8%), weaning from cardiopulmonary bypass (16.1%), preoperative use in high risk patients (13.0%) and refractory unstable angina (12.3%). Major IABP complications (major limb ischemia, severe bleeding, balloon leak, death directly due to IABP insertion or failure) occurred in 2.6% of cases; in-hospital mortality was 21.2% (11.6% with the balloon in place). Female gender, high age and peripheral vascular disease were independent predictors of a serious complication.

CONCLUSIONS

This registry provides a useful tool for monitoring the evolving practice of IABP. In the modern-day practice of IABP, complication rates are generally low, although in-hospital mortality remains high. There is an increased risk of major complications in women, older patients and patients with peripheral vascular disease.

Estimation of timing errors for the intraaortic balloon pump use in pediatric patients

The use of the intraaortic balloon pump (IABP) for managing acute left ventricular failure in pediatric patients is less successful than in adults. It is often reported that rapid pediatric heart rates make accurate timing difficult to achieve. Traditional IABP theory requires that the balloon inflate during diastole (after aortic valve closure), for optimum coronary pressure and flow augmentation, and deflate just before the next systole for optimal ventricular afterload reduction. Errors in timing balloon inflation and deflation may result in the reduced IABP efficacy seen in children. To investigate timing errors when using the traditional IABP inflation and deflation markers in pediatric patients, six patients (age, 2.2+/-1.4 years; weight, 11.5+/-3.9 kg) were studied intraoperatively. Radial artery pressure (RAP) waveforms from a standard, fluid-filled pressure monitoring system were recorded on an FM data tape recorder simultaneously with high-fidelity, aortic root pressure waveforms, aortic root flow waveforms, and M-mode echocardiography. For each patient, a sequence of five recorded waveforms was analyzed. The mean +/- standard deviation of the time delay between aortic root and RAP markers and percentage delay of the corresponding part of the cardiac cycle were determined. When compared with aortic root waveforms, the RAP waveform consistently showed a delay in the IABP timing markers. A 107+/-23 msec (53+/-11%) delay in diastolic inflation and a 92+/-11 msec (40+/-4%) delay in presystolic deflation was found. If IABP timing to the RAP markers were to be used, the delay in IABP inflation would result in reduced diastolic augmentation, and the delay in IABP deflation into the systolic period would increase afterload. M-mode echocardiography provided timing markers that were identical to those provided by high-fidelity aortic root pressure waveforms. The combined effect of these delays on IABP function could substantially reduce the efficacy of the IABP in pediatric patients, indicating the need for more accurate indices for IABP timing in this patient group.

Clinical evaluation of pulsatile flow mode of Terumo Capiox centrifugal pump

The Terumo Capiox centrifugal pump system possesses an automatic priming function in which the motor repeatedly stops and runs intermittently to eliminate air bubbles in the circuit through the micropores of the hollow-fiber membrane oxygenator. By modifying this mechanism, we have developed a pulsatile flow mode. In this mode, maximum and minimum pump rotational speeds can be independently set every 20 rpm in the range of 0 to 3,000 rpm. The duration of the pump run at maximum and minimum speeds can also be independently set every 0.1 s in the range of 0.2 to 15 s. In a clinical trial, after obtaining the desired flow rate, 2.4 L/min/m2 in nonpulsatile flow mode, a pulsatile flow mode of 60 cycles/min (with 1 cycle being maximum speed for 0.4 s and minimum speed for 0.6 s) was obtained by adding and subtracting 500 rpm to and from the rotational speed in nonpulsatile flow mode. Pulse pressures in the femoral artery and in the circuit just proximal to the perfusion cannula (6.5 mm Sarns high flow cannula with metal tip) were measured in 5 patients who underwent pulsatile cardiopulmonary bypass (CPB) for a coronary artery bypass graft (CABG), and compared to pulse pressures obtained by intraaortic balloon pumping (IABP) in 3 patients and by the pulsatile mode of the 3M Delphin pump in 3 patients. The platelet count, free hemoglobin, and beta-thromboglobulin (beta-TG) were measured and compared with measurements from another 5 patients who underwent nonpulsatile CPB. Although the pulse pressure measured in the circuit was 180 mm Hg on average, the pressure in the femoral artery was only 15 to 40 mm Hg with a mean of 20 mm Hg. In the same patients, 60 to 80 mm Hg pulse pressure was obtained with IABP. The pulse pressure obtained with the Delphin pump was not more than that obtained with the Terumo pump. There were no significant differences in percents of preoperative levels of platelet counts (pulsatile, 87.6 +/- 15.8% and nonpulsatile, 72.4 +/- 40.6%), free hemoglobin (pulsatile, 18 +/- 8 mg/dl and nonpulsatile, 25 = 7 mg/dl), and beta-TG (pulsatile 298 +/- 28 ng/ml and nonpulsatile, 312 +/- 143 ng/ml). In conclusion, although the pulsatile mode of the Terumo centrifugal pump did not exhibit any adverse effects hematologically, the pulse pressure obtained was unsatisfactorily small, mainly because of dumping caused by the perfusion cannula.

Significant left ventricular unloading with transaortic catheter venting during venoarterial bypass

Insufficient unloading of the left ventricle with blood stagnation is a main cause of unsuccessful left ventricular (LV) recovery during percutaneous cardiopulmonary support (PCPS). The purpose of this investigation was to evaluate the effectiveness of transaortic catheter venting (TACV) for LV unloading. Six adult mongrel dogs (mean weight 16.3 kg, range 14-20 kg) underwent venoarterial bypass (VAB) with TACV. Bypass flow ranged from 0.8-1.2 L/min, and TACV flow ranged from 160-240 ml/min. In addition to monitoring the standard hemodynamic parameters, the slope of the LV end-systolic pressure-volume relation (Emax) during transient occlusion of the inferior vena cava, the slope of the LV end-systolic pressure-stroke-volume relation (Ea), the stroke work (SW), the LV pressure-volume area (PVA), and the slope of the SW end-diastolic volume relation, the preload recruitable stroke work (PRSW) were assessed by means of a microtip manometer and a conductance catheter. The LV contractility (Emax) and aortic elastance (Ea) were equivalent in the 2 groups with or without TACV (7.7 +/- 1.1 versus 8.4 +/- 1.5 mm Hg/ml and 8.2 +/- 1.4 versus 7.6 +/- 1.3 mm Hg/ml). Comparing the measurements for the baseline to those for VAB with TACV, the SW was significantly reduced, and the PVA/SW was increased by TACV (1,685 +/- 309 versus 867 +/- 188 x 10(-4) J, p < 0.05 and 1.32 +/- 0.03 versus 1.58 +/- 0.11, p < 0.05, respectively). Furthermore, the PRSW was gradually decreased from the baseline value to the value resulting from VAB with TACV (75 +/- 8 versus 44 +/- 3 x 10(-4) J/ml, p < 0.01). In comparison, the percent reduction of SW between VAB and VAB with TACV tended to be increased by TACV (23.2 +/- 7.2% versus 46.9 +/- 7.7%, p = 0.05). These results suggest that TACV might reduce LV work (SW and PRSW) and might increase the LV energetic charge. In conclusion, TACV would be an adjunctive technique to VAB or PCPS for patients with LV failure.

Are intraaortic balloons suitable for reuse? A survey study of 112 used intraaortic balloons

To assess the safety of reusing single-use intraaortic balloon devices (IABs), 112 used devices were investigated in terms of physical integrity, gas leakage inspection, mechanical performance, surface chemistry and morphology, and physical stability. These IABs were all used clinically only once, and the duration of the IABs in vivo ranged from 6 to 312 h. Macroscopic examination of the balloons and the outer catheters revealed no obvious change in either shape or color. No discernible abrasions or cracks were observed on the balloons. However, 61% of the balloons were creased, and 40% of the central lumens and 21% of the sheaths showed visible bending flaws. Moreover, 65% of the balloons and 38% of the central lumens were contaminated by visible residual organic debris. The physical integrity of each device was verified in a specially designed leakage-fatigue tester for 72 h. Ninety-seven percent of the devices passed the leakage inspection. Stress-strain testing, differential scanning calorimetry, attenuated total reflection-Fourier transform infrared, and scanning electron microscopy analyses clearly indicated that there were no significant differences in the mechanical properties, bulk material morphology, surface chemistry, and external surface morphology between the used balloons and virgin controls. Although some surface modifications occurred on the internal side of the balloons, the external surfaces of most balloons suffered no trauma. Most of the used IABs examined in this study maintained physical and mechanical properties similar to those of the virgin devices. The chemistry of the balloon material was stable after short-term in vivo use. However, it does not seem possible to establish a rigorous protocol of cleaning, sterilization, and inspection to guarantee a safer reuse of these devices. The presence of residual organic debris that cannot be eliminated results in an imperative preclusion not to reuse the IABs.

Current status of heart assist and replacement in Taiwan

The first clinical application of intraaortic balloon pumps (IABP) in Taiwan was in 1976 to treat post-cardiotomy cardiogenic shock. It is now the most commonly used circulatory assist. From 1991 to 1995, 186 patients received IABP support with an overall mortality rate 41.9%. The male patients had the best survival rate, 67%, after coronary artery bypass grafting. The first extracorporeal membrane oxygenation (ECMO) was in 1987 to treat intractable heart failure caused by severe acute rejection after heart transplantation. Because of poor outcome, patients only received ECMO sporadically during the past years. From November 1994 to November 1995, 30 patients received ECMO support with 50% of them eventually weaned from ECMO and 27% discharged. For short-term support or emergency rescue, ECMO was a good choice. When long-term support was required, the ventricular assist device (VAD) was a more suitable assist. One patient who received Thermedics VAD developed right heart failure and finally died of sepsis and multiple organ failure. VAD should be implanted before the secondary organ failure. The first successful clinical heart transplantation in Taiwan was performed on July 17, 1987. From 1991 to 1995, 102 patients underwent heart transplantation. The operative mortality was 3.9%, and the 1 and 5 year actuarial survival rates were 86 +/- 3% and 77 +/- 5%, respectively. To improve the success rate of clinical heart transplantation, organ donation should be encouraged.

Mock test characteristic of intraaortic balloon pump using linear motor

This article describes the composition of the intraaortic balloon pump (IABP) system, which uses a linear pulse motor, that is, the linear type of IABP, and the results of the mock test that was performed. The expansion time is 100-110 ms, and the contraction time is 85-95 ms at the balloon of the linear type IABP. This level is similar to that of the IABP system used in the market. When the speed of the mover is 0.3 m/s, the necessary thrust of the linear pulse motor to drive the balloon of the IABP is 200 N. The conversion efficiency from the bellows to the balloon is 5.6%, and the efficiency of the entire linear type IABP system is 0.6%. The volume of the entire system is 45 L, and the mass is 40 kg excluding the chassis. Therefore, there is an expectation that the IABP system can be miniaturized to about half of the conventional model.

Prognosis in cardiogenic shock after acute myocardial infarction in the interventional era

OBJECTIVES

The purpose of this study is to describe the outcome in cardiogenic shock treated with aggressive reperfusion therapy and to identify factors predictive of in-hospital and long-term mortality.

BACKGROUND

Cardiogenic shock is the most common cause of death in patients admitted to the coronary care unit. Although studies have reported lower mortality rates in shock treated with angioplasty, few studies have described a cohort of patients with shock who were not selected because they were most likely to benefit from reperfusion therapy.

METHODS

A consecutive series of 200 patients admitted with acute myocardial infarction complicated by cardiogenic shock were studied.

RESULTS

The in-hospital mortality rate was 53%. Variables with significant univariable association with in-hospital death included patency of the infarct-related artery, patient age, lowest cardiac index, highest arteriovenous oxygen difference and left main coronary artery disease. The most important independent predictors of in-hospital death were patency of the infarct-related artery, cardiac index and peak creatine kinase, MB fraction. The mortality rate in patients with patent infarct-related arteries was 33% versus 75% in those with closed arteries and 84% in those in whom arterial patency was unknown. Patients who survived to hospital discharge were followed up for a median of 2 years, with a mortality rate of 18% after 1 year. The best descriptors of the relation between these variables and postdischarge mortality included age, peak creatine kinase, ejection fraction and patency of the infarct-related artery.

CONCLUSIONS

In a large consecutive series of patients with cardiogenic shock with complete follow-up, patency of the infarct-related artery was most strongly associated with in-hospital and long-term mortality. This finding supports an aggressive interventional strategy in patients with cardiogenic shock.

Retroperfusion and balloon support to improve coronary revascularization

Coronary venous retroperfusion and Intra-Aortic Balloon Pump (IABP) support are methods currently utilized to reduce ischemic damage prior to revascularization of acutely ischemic myocardium. This study was undertaken to determine whether combining coronary venous retroperfusion using Pressure Controlled Intermittent Coronary Sinus Occlusion (PICSO) with the IABP would result in improved salvage of ischemic myocardium. In 40 adult pigs, the second and third diagonal vessels were occluded with snares for 1 1/2 hours followed by 1/2 hours of cardioplegic arrest and 3 hours of reperfusion with the snares released. During the period of coronary occlusion prior to arrest, 10 pigs received the IABP, 10 had PICSO, 10 had PICSO+IABP, while 10 had no intervention (Unmodified). Ischemic damage was assessed by echocardiographic wall motion scores, myocardial pH, and the area of necrosis/area of risk using histochemical staining. Both PICSO and the IABP alone significantly reduced ischemic damage. However, the best wall motion scores, highest pH, and least necrosis was seen in the IABP+PICSO group. We conclude that the combination of coronary venous retroperfusion using PICSO and the IABP results in the most optimal recovery of acutely ischemic myocardium during emergent surgical revascularization.

Prophylactic use of the intra-aortic balloon pump in high-risk cardiac patients undergoing noncardiac surgery: a decision analytic view

OBJECTIVE

As the indications for the intra-aortic balloon pump (IABP) continue to evolve, a potential new use may be the prophylactic preoperative insertion of the IABP in the high-risk cardiac patient undergoing noncardiac surgery. Our objective is to present a general approach to the high-risk cardiac patient who may benefit from the prophylactic insertion of the IABP.

DESIGN

Case reports and a decision analysis.

METHODS

A decision model was constructed that weighs the risk of life-threatening postoperative complications against the risk of vascular complications, including surgery and possible amputation, from IABP insertion.

RESULTS AND CONCLUSIONS

A review of the literature identified 10 patients who underwent IABP placement prior to noncardiac surgery. These patients, along with our three cases, define a population of patients for whom the prophylactic IABP may be useful. This population includes patients with coronary artery disease (CAD) for whom bypass grafting is not an option due to: (1) inoperable CAD; (2) a severe coexisting disease process (such as a malignancy); or (3) the emergent nature of the noncardiac procedure. The decision analysis suggests that patients whose preoperative assessment places them at very high risk for postoperative complications (Goldman class IV or Detsky class III undergoing major surgery) may benefit the most from prophylactic placement of an IABP prior to noncardiac surgery.

Effect of intra-aortic balloon counterpulsation on right-left shunt following right ventricular infarction

Intra-aortic balloon counterpulsations decrease the left ventricular end-diastolic pressure and, subsequently, the left atrial pressure in patients with impaired myocardial function following myocardial infarction. This paper reports a case of right ventricular infarction in a patient with patency of the oval foramen where the use of intra-aortic balloon counterpulsation led to the perpetuation of the right-to-left shunt.

Clinical evaluation of the Percor percutaneous intraaortic balloon: cooperative study of 722 cases

Clinical experience with the Percor percutaneous intraaortic balloon (IAB) was reviewed in 722 cases performed by 59 clinicians (35 surgeons and 24 cardiologists). Compared with standard IABs, Percor was judged to provide easier insertion by 88% of clinicians, easier femoral-iliac passage by 29%, easier aortic passage by 36%, and easier final positioning by 19%; the Percor IAB was rated more difficult in these respects by 2-5% of users; the rest of the responders found no significant difference in these measures. Technical problems included an inability to negotiate sclerotic vessels in 12.6%, delayed hemostasis in 1.9%, and the need for surgical repair of the arteriotomy site in 2%. Medical complications included peripheral ischemia in 5.3%, emboli in 3.6%, arterial dissection in 1.9%, dislodged arterial plaque in 1.1%, perforation of the arterial tree in 1.0%, local femoral thrombosis in 1.0%, and poor intraoperative hemostasis in 0.3%. Local wound infection, ischemic amputation or neuropathic sequelae were not reported. Mechanical counterpulsation with Pecor was equivalent to that of standard IABs, but by subjective judgments, 80% rated Percor more desirable and 47% safer; 3% rated it less desirable and 10% less safe. With Percor, earlier clinical use of IAB pumping was seen by 73%, and new or additional indications were recommended by 19%.

[The efficacy of the intra-aortic balloon pump for patients with heart failure complicating acute myocardial infarction (author's transl)]

Assisted circulation was carried out with the help of an intra-aortic balloon pump in 22 patients with acute transmural myocardial infarction and heart failure (despite medication). Two patients died in hospital. The combination of the balloon pump and nitrates proved to be particularly effective. The follow-up examination of the survivors showed a distinct pulmonary arterial pressure during ergometry. All of the examined patients revealed extensive akinetic and diskinetic areas, significant stenosis being detectable either in the proximal area of the Ramus descendens anterior or in two or three blood vessels.

[Means of improving the operational safety of balloon-pump counter-pulsation apparatus]

The apparatus of assisted circulation, in particular those intended for counter-pulsation with the pump-balloon, as concerns their reliability and safety to units whose failure presents immediate danger for the patient's life. An analysis of modern batch manufactured apparatus revealed a tendency toward widening the scope and complicating the signallization means of automatic protection and preventing failures. It is shown that the reliability of the units for counter-pulsation with the pump-balloon is not only a technical, but also a biomedicocybernetic problem. Substance is given to the need for introduction into the system of the apparatus for assisted circulation of sand-by actuating mechanisms for secure a purposeful influence on the physiological parameters of the organism.