The effects of intra-aortic counterpulsation on cardiac performance and metabolism in shock associated with acute myocardial infarction

Mechanical Circulatory Support in Right Ventricular Failure

Right ventricular dysfunction presents unique challenges in patients with cardiopulmonary disease. When optimal medical therapy fails, mechanical circulatory support is considered. Devices can by classified according to whether they are deployed percutaneously or surgically, whether the pump is axial or centrifugal, whether the right ventricle is bypassed directly or indirectly, and whether the support is short term or long term. Each device has advantages and disadvantages. Acute mechanical circulatory support is a suitable temporizing strategy in advanced heart failure. Future research in right ventricular mechanical circulatory support will optimize device management, refine patient selection, and ultimately improve clinical outcomes.

Complications from percutaneous-left ventricular assist devices versus intra-aortic balloon pump in acute myocardial infarction-cardiogenic shock

BACKGROUND

There are limited data on the complications with a percutaneous left ventricular assist device (pLVAD) vs. intra-aortic balloon pump (IABP) in acute myocardial infarction-cardiogenic shock (AMI-CS).

OBJECTIVE

To assess the trends, rates and predictors of complications.

METHODS

Using a 17-year AMI-CS population from the National Inpatient Sample, AMI-CS admissions receiving pLVAD and IABP support were evaluated for vascular, lower limb amputation, hematologic, neurologic and acute kidney injury (AKI) complications. In-hospital mortality, hospitalization costs and length of stay in pLVAD and IABP cohorts with complications was studied.

RESULTS

Of 168,645 admissions, 7,855 (4.7%) receiving pLVAD support. The pLVAD cohort had higher comorbidity, cardiac arrest (36.1% vs. 29.7%) and non-cardiac organ failure (74.7% vs. 56.9%) rates. Complications were higher in pLVAD compared to IABP cohort-overall 69.0% vs. 54.7%; vascular 3.8% vs. 2.1%; lower limb amputation 0.3% vs. 0.3%; hematologic 36.0% vs. 27.7%; neurologic 4.9% vs. 3.5% and AKI 55.4% vs. 39.1% (all p<0.001 except for amputation). Non-White race, higher comorbidity, organ failure, and extracorporeal membrane oxygen use were predictors of complications for both cohorts. The pLVAD cohort with complications had higher in-hospital mortality (45.5% vs. 33.1%; adjusted odds ratio 1.65 [95% confidence interval 1.55-1.75]), shorter duration of hospital stay, and higher hospitalization costs compared to the IABP cohort with complications (all p<0.001). These results were consistent in propensity-matched pairs.

CONCLUSIONS

AMI-CS admissions receiving pLVAD had higher rates of complications compared to the IABP, with worse in-hospital outcomes in the cohort with complications.

Mechanical Circulatory Assist Devices: Available Modalities and Review of Literature

Despite advancements in the field interventional cardiology, the prognosis in patients who suffer from cardiogenic shock is poor. Over the years, the use of percutaneous mechanical circulatory support (MCS) devices has increased with the aim to improve short- and long-term outcomes. In this article, we aim to review the different modalities available for MCS devices and current literature comparing their uses.

Complications of Temporary Percutaneous Mechanical Circulatory Support for Cardiogenic Shock: An Appraisal of Contemporary Literature

Cardiogenic shock (CS) is associated with hemodynamic compromise and end-organ hypoperfusion due to a primary cardiac etiology. In addition to vasoactive medications, percutaneous mechanical circulatory support (MCS) devices offer the ability to support the hemodynamics and prevent acute organ failure. Despite the wide array of available MCS devices for CS, there are limited data on the complications from these devices. In this review, we seek to summarize the complications of MCS devices in the contemporary era. Using a systems-based approach, this review covers domains of hematological, neurological, vascular, infectious, mechanical, and miscellaneous complications. These data are intended to provide a balanced narrative and aid in risk-benefit decision-making in this acutely ill population.

How New Support Devices Change Critical Care Delivery

Mechanical support devices are used to support failing cardiac, respiratory, or both systems. Since Gibbon developed the cardiopulmonary bypass in 1953, collaborative efforts by medical centers, bioengineers, industry, and the National Institutes of Health have led to development of mechanical devices to support heart, lung, or both. These devices are used as a temporary or long-term measures for acute collapse of circulatory system and/or respiratory failure. Patients are managed on these support devices as a bridge to recovery, bridge to long term devices, or bridge to transplant. The progress in development of these devices has improved mortality and quality of life in select groups of patients. Care of these patients requires a multidisciplinary team approach, which includes cardiac surgeons, critical care physicians, cardiologists, pulmonologists, nursing staff, and perfusionists. Using a team approach improves outcomes in these patients.

Assessment of Intra-Aortic Counterpulsation in an Animal Model of Heart Failure and Myocardial Ischemia

The effectiveness of intra-aortic balloon pumping (IABP) is currently evaluated using indirect indexes. The diastolic pressure augmentation is quantified using the subendocardial viability ratio (SEVR) and the DABAC/SABAC index (areas beneath the aortic pressure-time signals during the diastolic and systolic periods, respectively). The SEVR requires invasive recordings of left ventricular pressure; the DABAC/SABAC index may represent an alternative, since it only requires an aortic pressure signal. Nonetheless, it has never been used in an animal model of counterpulsated heart failure and ischemia-reperfusion episode. The aims of this work were: (i) to develop an animal model of heart failure, with a myocardial ischemia-reperfusion episode, treated with IABP during the reperfusion period; (ii) to evaluate the effects of the IABP using the SEVR and DABAC/SABAC indices; and (iii) to assess the relationship between both ratios. Cardiovascular parameters were obtained in anesthetized sheep, in which induced heart failure and ischemia-reperfusion episodes were monitored with and without IABP 1:2. Systolic and diastolic blood pressure signals were assessed in the aorta and in the left ventricle. Values of cardiac output and left ventricular wall thickness signals were obtained. Induction of ischemia and heart failure determined decreases in SEVR and DABAC/SABAC indices with respect to their basal stage (0.807 ± 0.118 vs. 0.601 ± 0.107, P < 0.05 and 1.062 ± 0.136 vs. 0.902 ± 0.161, P < 0.05, respectively). Counterpulsated animals whose myocardial reperfusion was accompanied by heart failure showed a significant improvement of wall thickening fraction along time (R²  = 0.7627, P < 0.001). During counterpulsated heart failure accompanied by myocardial reperfusion, the SEVR was positively correlated with DABAC/SABAC index.

Intra-aortic balloon pump in cardiogenic shock: state of the art

ABSTRACT The clinical definition of cardiogenic shock is that of a low cardiac output and evidence of tissue hypoxia in the presence of adequate blood volume. Cardiogenic shock is the main cause of death related to acute myocardial infarction (AMI), with a mortality rate of 45-70% in the absence of aggressive and highly specialized technical care. The intra-aortic balloon pump (IABP) is one of the most widely used mechanical assisting devices. During the last two decades, about 42% of patients with AMI who evolved with cardiogenic shock received mechanical circulatory assistance with IABP. Its clinical indication has been based on non-randomized studies and registry data. Recent studies have shown that the use of IABP did not reduce 30-day mortality in patients with AMI and cardiogenic shock treated with the strategy of early myocardial revascularization as the planned primary objective. The guidelines of the American Heart Association and of the European Society of Cardiology have reassessed their recommendations based on the results of meta-analyzes, including the IABP-SCHOCK II Trial study, which did not evidence an increase in survival of patients who received mechanical support with IABP. This review article addresses the clinical impact of IABP use in the cardiogenic shock caused by AMI.

Impact of intra-aortic balloon pump on short-term clinical outcomes in ST-elevation myocardial infarction complicated by cardiogenic shock: A "real life" single center experience

OBJECTIVE

To analyze the use and impact of the intra-aortic balloon pump (IABP) upon the 30-day mortality rate and short-term clinical outcome of non-selected patients with ST-elevation acute myocardial infarction (acute STEMI) complicated by cardiogenic shock (CS).

DESIGN

A single-center retrospective case-control study was carried out.

SETTING

Coronary Care Unit.

PATIENTS

Data were collected from 825 consecutive patients with acute STEMI admitted to a Coronary Care Unit from January 2009 to August 2015. Seventy-three patients with CS upon admission subjected to emergency percutaneous coronary intervention (PCI) were finally included in the analysis and were stratified according to IABP use (44 patients receiving IABP).

VARIABLES

Cardiovascular history, hemodynamic situation upon admission, angiographic and procedural characteristics, and variables derived from admission to the Coronary Care Unit.

RESULTS

Cumulative 30-day mortality was similar in the patients subjected to IABP and in those who received conventional medical therapy only (29.5% and 27.6%, respectively; HR with IABP 1.10, 95% CI 0.38-3.11; p=0.85). Similarly, no significant differences were found in terms of the short-term clinical outcome between the groups: time on mechanical ventilation, days to hemodynamic stabilization, vasoactive drug requirements and stay in the Coronary Care Unit. Poorer renal function (HR 3.9, 95% CI 1.4-10.6; p=0.008), known peripheral artery disease (HR 3.3, 95% CI 1.2-9.1; p=0.019) and a history of diabetes mellitus (HR 3.2, 95% CI 1.2-8.1; p=0.018) were the only variables independently associated to increased 30-day mortality.

CONCLUSION

In our "real life" experience, IABP does not modify 30-day mortality or the short-term clinical outcome in patients presenting STEMI complicated with CS and subjected to emergency percutaneous coronary revascularization.

Management of Cardiogenic Shock Due to Acute Coronary Syndromes

Despite advances in the treatment of patients with acute coronary syndromes, there has been no significant decrease in the incidence of cardiogenic shock, while its mortality remains frustratingly high. Shock is a progressive state of hypotension (systolic blood pressure <90 mm Hg) lasting at least 30 minutes, which leads to systemic hypoperfusion. It is more common in patients with ST-segment elevation myocardial infarction than in patients with other acute coronary syndromes. Revascularization is associated with better outcomes than intensive medical therapy, especially in patients <75 years of age with cardiogenic shock. Adjunctive therapies include inotropes, vasopressor therapy, intra-aortic balloon pump counterpulsation, and IIb/IIIa blockade to prevent no-reflow phenomenon during primary percutaneous transluminal coronary angioplasty. Other adjunctive therapies which are investigated are improved mechanical support devices, and as medical therapy for myocyte protection nicorandil, glucose/insulin/potassium infusions and direct inhibition of Na+/H+ exchanger.

Clinical characteristics and outcomes after unplanned intraaortic balloon counterpulsation in the Counterpulsation to Reduce Infarct Size Pre-PCI Acute Myocardial Infarction trial

BACKGROUND

Despite advances in primary percutaneous coronary intervention (pPCI) and regional systems of care, the development of cardiogenic shock is associated with poor clinical outcomes in patients with ST-segment elevation myocardial infarction (STEMI). We sought to better characterize the baseline characteristics and clinical outcomes of patients who underwent crossover to intraaortic balloon counterpulsation (IABC) in the CRISP AMI trial.

METHODS

Patients with anterior STEMI were randomized to IABC before pPCI or pPCI alone. Infarct size and 6-month clinical outcomes were evaluated in patients both in the pPCI-alone group who did undergo crossover to IABC and those who did not undergo crossover to IABC.

RESULTS

Among 176 patients randomized to pPCI alone, 161 patients did not later receive IABC during the index hospitalization, and 15 patients (8.5%) underwent crossover and did receive unplanned IABC. Hypotension and/or cardiogenic shock precipitated crossover to IABC in 12 patients (80%). Patients who underwent crossover to IABC demonstrated lower systolic and diastolic blood pressures on admission. At 6 months, rates of death (26.7% vs 3.1%, P = .003), readmission for severe hypotension (53.3% vs 3.7%, P < .001), resuscitated cardiac arrest, and ventricular arrhythmia were higher in the group that did crossover to IABC. Crossover to IABC was not associated with increased infarct size.

CONCLUSIONS

The most significant predictor of crossover to IABC in the setting of anterior STEMI was relative hypotension at the time of hospital admission, and crossover to IABC in CRISP AMI was associated with significantly worse clinical outcomes.

Control of acute phase intestinal bleeding after percutaneous coronary intervention by discontinuing dual antiplatelet therapy and implementing intra-aortic balloon pumping

Aspirin's efficacy for the prevention of secondary vascular disease is well supported. However, more attention should be given to its side effects, especially gastrointestinal injury. A 62-year-old man suffered acute myocardial infarction of the left main trunk. Although a percutaneous coronary intervention, using a bare metal stent, was successful, intractable in-bowel bleeding developed. To control the bleeding, we discontinued dual antiplatelet therapy during the acute phase, and used intra-aortic balloon pumping to provide sufficient coronary flow to prevent stent thrombosis. This strategy controlled intestinal bleeding without any thrombotic complications, indicating that intra-aortic balloon pumping is effective for preventing stent thrombosis. <Learning objective: Aspirin often causes bleeding complications, especially in the gastrointestinal tract. We experienced a case with severe intestinal bleeding of unknown origin during the acute phase after percutaneous coronary intervention for acute myocardial infarction. The dual antiplatelet therapy was necessarily stopped, which could have resulted in stent thrombosis. We used intra-aortic balloon pumping to prevent the stent thrombosis through coronary flow augmentation.>.

Intra-aortic balloon counterpulsation in contemporary practice - where are we?

The intra-aortic balloon pump (IABP) remains the most widely used form of mechanical circulatory support in current clinical practice. This article will review the current evidence to guide IABP use, focussing on large registry and prospective, randomised data, and seek to establish appropriate roles for the IABP in contemporary practice. Despite a paucity of clinical evidence, the IABP remains a useful clinical tool in selected settings, although its routine, up-front use in relatively unselected MI populations is not supported by data. Although current evidence no longer supports routine use in certain high-risk groups, further studies of appropriately selected high-risk patients may yet demonstrate benefit in patients with moderate-severe degrees of shock.

Intra-aortic balloon pump in patients with cardiogenic shock complicating myocardial infarction: a systematic review and meta-analysis of randomized trials (protocol)

BACKGROUND

Cardiogenic shock is the leading cause of death in patients with acute myocardial infarction. Despite significant advancements in health technology and research, hospital mortality approaches 50%. The intra-aortic balloon pump is a mechanical hemodynamic assist device that has been used for over 40 years in the management of patients with cardiogenic shock. A recent randomized trial suggests that the use of intra-aortic balloon pumps does not reduce mortality in patients with ischemic cardiogenic shock.

METHODS

We plan to search MEDLINE, EMBASE, and the Cochrane Trial Registry for potentially eligible randomized trials that compare the use of intra-aortic balloon pump with no mechanical device support in patients with cardiogenic shock. No date, language or journal limitations will be applied. Two reviewers will independently screen and identify eligible studies using predefined eligibility criteria. Data abstraction will be done independently and in duplicate. We plan to use RevMan software to generate pooled estimates across included studies, using the previously published method of DerSimonian and Laird. We will report pooled estimates as risk ratios with 95% confidence intervals for binary outcomes, and as mean differences with 95% confidence intervals for continuous outcomes. We will assess the quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

DISCUSSION

The aim of this systematic review and meta-analysis is to summarize the available evidence on the efficacy of the intra-aortic balloon pump in cardiogenic shock. Systematic review registration: PROSPERO CRD42014007056.

Counterpulsation: a concept with a remarkable past, an established present and a challenging future

The intra-aortic balloon pump (IABP), which is the main representative of the counterpulsation technique, has been an invaluable tool in cardiologists' and cardiac surgeons' armamentarium for approximately half a century. The IABP confers a wide variety of vaguely understood effects on cardiac physiology and mechano-energetics. Although, the recommendations for its use are multiple, most are not substantially evidence-based. Indicatively, the results of recently performed prospective studies have put IABP's utility in the setting of post-infarction cardiogenic shock into question. However, the particular issue remains open to further research. IABP support in high-risk patients undergoing PCI is associated with favorable long-term clinical outcome. In cardiac surgery, the use of IABP in cases of peri-operative low-output syndrome, refractory angina or ischemia-related mechanical complications is a usual, but poorly justified strategy. Anecdotal cases of treatment of incessant ventricular arrhythmias, reversal of right ventricular dysfunction and partial myocardial recovery have also been reported with its use. Converging data demonstrate the potential of safe long-term IABP support as a bridge to decision making or a bridge to transplantation modality in patients with heart failure. The feasibility of IABP insertion via other than the femoral artery sites enhances this potential. Despite the fact that several other counterpulsation devices have been developed and tested overtime none has managed to substitute the IABP, which continues to be most frequently used mechanical assist device.

Review: The New Concept of ‘‘Interventional Heart Failure Therapy’’: Part 2—Inotropes, Valvular Disease, Pumps, and Transplantation

Recent advances in heart failure therapy include a variety of mechanical and device-based technologies that target structural aspects of heart failure that cannot be treated with drug therapy alone; these newer therapies can collectively be described as interventional heart failure therapy. This article is the second in a 2-part series reviewing interventional heart failure therapy. Interventions included in this discussion include those indicated for the treatment of end-stage refractory heart failure, including interventional medical therapy, interventional treatment of valvular disease, mechanical assist devices, and heart transplantation. Also included is a review of the currently available catheter-based pumps, which are intended to provide temporary support in patients with acute hemodynamic compromise. The use of cellular or stem cell therapy for the treatment of heart failure is an emerging interventional therapy and data supporting its use for the treatment heart failure will also be presented, as will a discussion of the role of palliative care and self-care in heart failure therapy.

Peripheral hemodynamics in assisted circulation with intra-aortic balloon pumping in patients with cardiogenic shock

Seven patients treated for cardiogenic shock were studied with and without intra-aortic balloon pumping (IABP). Calf and forearm blood flows were determined with a Dohn plethysmograph and arterial pressures were registered intra-arterially and in the great toe and thumb with the cuff method. During IABP, an augmented flow was registered in the arms and legs and accurate arterial BPs could also be determined from the extremities. The findings demonstrate a beneficial effect of IABP on peripheral flow, expecially in patients who could be weaned off the pump.

Usefulness of multiaxis echocardiography in assessment of the left ventricle in ischemic heart disease. A review

Echoventriculography, a multiaxis M-mode echocardiographic technique, was developed to examine in detail the regional wall motions of the left ventricle. The basic technical aspects and limitations are described, and experience is reviewed on 263 healthy subjects or patients with ischaemic heart disease. The reliability in detecting site and size of asynergic segments was excellent as related to electrocardiographic and thallium scintigraphic sites of acute infarction, and with left ventricular cineangiograms in chronic coronary heart disease. The correlation with pathologic anatomic size of infarct in 24 consecutive patients was r = 0.88 (p less than 0.001) when expressed by a percentage of the left ventricular horizontal circumference. 94% of 111 infarcted segments were correctly detected by echo; only the posteroseptal and the most lateral regions remain out of the methodological range. The method separated old infarct scars from fresh necrosis. Decreasing echo contraction index correlated with increasing severity of coronary obstructions in 43 patients studied for coronary artery surgery. In 15 infarct patients the M-mode technique was more sensitive than two-dimensional echocardiography in recording asynergic segments or endocardial echoes. The multiple segmental echoventriculographic index decreased parallel with clinical severity of acute infarction (r = -0.79, p less than 0.001; 30 patients). There was a 88% (p less than 0.01) concordance between the reduction of the ST segments (-30%) and the recovery of the mechanical function in the ischaemic myocardial segments (+26%) after beta blockade with pindolol in 22 patients with acute infarction. Methylprednisolone showed no improvement. With dopamine the left ventricular size decreased markedly (p less than 0.0005). Echoventriculography thus seems to be very informative in evaluation of chronic or acute left ventricular dysfunction, despite the rather demanding nature of the technique in practice.

Effects of metabolic and pharmacologic interventions on myocardial infarct size following coronary occlusion

A number of hemodynamic, pharmacologic and metabolic interventions were found to change the extent of acute ischemic injury of the myocardium and subsequent necrosis following experimental coronary artery occlusion. Reduction in myocardial damage occurred by decreasing myocardial oxygen demands (beta-adrenergic blocking agents, intra-aortic balloon counterpulsation, external counterpulsation, nitroglycerin, decreasing afterload in hypertensive patients, inhibition of lipolysis, and digitalis in the failing heart); by increasing myocardial oxygen supply either directly (coronary artery reperfusion or elevating arterial pO2), or through collateral vessels (elevation of coronary perfusion pressure by alpha-adrenergic agonists, intra-aortic balloon counterpulsation); or by increasing plasma osmolality (mannitol, hypertonic glucose); presumably by augmenting anaerobic metabolism (glucose-insulin-potassium, hypertonic glucose); by enhancing transport to the ischemic zone of substrates utilized in energy production (hyaluronidase); by protecting against autolytic and heterolytic damage (hydrocortisone, cobra venom factor, aprotinin). Augmentation of myocardial ischemic damage occurred as a consequence of increasing myocardial oxygen requirements (isoproterenol, glucagon, ouabain, bretylium tosylate, tachycardia); by decreasing myocardial oxygen supply either directly (hypoxia, anemia) or through reduction of collateral flow (hemorrhagic hypotension, minoxidil) or by decreasing substrate availability glycemia). Pilot studies have been carried out in patients with hyaluronidase, nitroglycerin, intra-aortic balloon counterpulsation, beta-blocking agents and Arfonad and have shown that these interventions may also reduce myocardial damage, suggesting that the concept of reduction in infarct size following coronary occlusion is applicable clinically.

Prophylactic intra-aortic balloon pump is useful to facilitate percutaneous coronary interventions: images from rescue cases

Images are presented of coronary reperfusion that occurred shortly after insertion of an intra-aortic balloon pump for counter-pulsation in 3 patients with acute myocardial infarction refractory to thrombolytic therapy and hemodynamic derangement. It is shown that prophylactic intra-aortic balloon pump use may facilitate percutaneous coronary intervention during acute myocardial infarction and it is useful to provide a visual assessment of myocardial flow restoring.

Effects of intra-aortic balloon counterpulsation on coronary pressure in patients with stenotic coronary arteries

BACKGROUND

The benefits of intra-aortic balloon pumping (IABP) usage reportedly occur through systolic unloading of the left ventricle and the augmentation of diastolic coronary flow. The aim of this study was to assess the change in intracoronary pressure distal to the coronary stenosis after the IABP by using an intracoronary pressure wire.

METHODS

Hemodynamic variables and intracoronary pressure data were measured in 16 patients requiring IABP for clinical indication (11 vessels with coronary stenosis and 5 normal vessels were enrolled). Coronary pressure was measured directly in each vessel with and without IABP support.

RESULTS

The diastolic aortic pressure during IABP increased compared with that without the IABP (97.9 +/- 11.7 vs 80.3 +/- 10.7 mm Hg, P < .01). The systolic aortic and intracoronary pressure during the IABP decreased (aortic pressure: 83.8 +/- 10.4 vs 95.9 +/- 11.3 mm Hg, P < .01, intracoronary pressure: 67.6 +/- 16.5 vs 76.2 +/- 20.4 mm Hg, P < .01). The diastolic distal coronary pressure (Pd) increased during the IABP in healthy coronary arteries (87.3 +/- 4.8 vs 72.1 +/- 10.3 mm Hg, P < .05). However, Pd in stenotic coronary arteries with the IABP did not increase statistically compared with those without the IABP (44.0 +/- 21.3 vs 42.8 +/- 17.9 mm Hg). There was a significant correlation between the change in Pd after IABP insertion and percent diameter stenosis calculated by quantitative coronary angiography (r2 = 0.51, P < .001).

CONCLUSIONS

In the presence of a critical coronary stenosis, the IABP does not increase the diastolic coronary pressure distal to the stenosis. Thus, the major effect of IABP on high-risk patients with severe coronary stenosis may relate to the reduction of oxygen demand by systolic unloading more than diastolic augmentation of the coronary flow.

Aortic counterpulsation: A review of the hemodynamic effects and indications for use

In the ever evolving field of cardiovascular medicine and coronary intervention, the intra-aortic balloon pump (IABP) is a mature technology, which still plays an important role. The balloon pump invasively supports patient hemodynamics by augmenting diastolic perfusion and increasing diastolic blood pressure, thereby increasing coronary perfusion and reducing afterload. Its efficacy has been demonstrated in a multitude of clinical situations, including acute coronary syndromes, high-risk coronary interventions, cardiogenic shock, and cardiovascular surgery. The potential complications of aortic counterpulsation are serious, although much lower than once feared. With proper patient selection, insertion technique, and management, the IABP is a powerful tool to assist in the treatment of patients with cardiovascular disease. This article will review the hemodynamics, indications, and complications associated with its use.

Relation between hospital intra-aortic balloon counterpulsation volume and mortality in acute myocardial infarction complicated by cardiogenic shock

BACKGROUND

Increasing evidence suggests an inverse relationship between outcome and the total number of invasive cardiac procedures performed at a given hospital. The purpose of the present study was to determine if a similar relationship exists between the number of intra-aortic balloon counterpulsation (IABP) procedures performed at a given hospital per year and the in-hospital mortality rate of patients with acute myocardial infarction complicated by cardiogenic shock.

METHODS AND RESULTS

We analyzed data of 12 730 patients at 750 hospitals enrolled in the National Registry of Myocardial Infarction 2 from 1994 to 1998. The hospitals were divided into tertiles (low-, intermediate-, and high-IABP volume hospitals) according to the number of IABPs performed at the given hospital per year. The median number of IABPs performed per hospital per year was 3.4, 12.7, and 37.4 IABPs at low-, intermediate-, and high-volume hospitals, respectively. Of those patients who underwent IABP, there were only minor differences in baseline patient characteristics between the 3 groups. Crude mortality rate decreased with increasing IABP volume: 65.4%, lowest volume tertile; 54.1%, intermediate volume tertile; and 50.6%, highest volume tertile (P for trend <0.001). This mortality difference represented 150 fewer deaths per 1000 patients treated at the high IABP hospitals. In the multivariate analysis, high hospital IABP volume for patients with acute myocardial infarction was associated with lower mortality (OR=0.71, 95% CI=0.56 to 0.90), independent of baseline patient characteristics, hospital factors, treatment, and procedures such as PTCA.

CONCLUSIONS

Among the myocardial infarction patients with cardiogenic shock who underwent IABP placement, mortality rate was significantly lower at high-IABP volume hospitals compared with low-IABP volume hospitals.

Effect of intraaortic balloon pumping on left ventricular function in patients with persistent ST segment elevation after revascularization for acute myocardial infarction

The purpose of the present study was to assess the impact of intraaortic balloon pumping (IABP) in patients with persistent ST elevation who underwent revascularization within 6 h of their first acute anterior myocardial infarction (AMI). Persistent ST elevation after revascularization was defined as being > or =50% of the initial value on return to the coronary care unit. Twenty-four patients were treated without IABP (control group) and 27 patients were treated with IABP (IABP group). There was no significant difference between the 2 groups in pretreatment left ventricular ejection fraction (LVEF), end-diastolic volume index or end-systolic volume index. After 137+/-46 days, the change in the LVEF was significantly higher in the IABP group than in the control group (5+/-13% vs 13+/-15%, p=0.04). However, the left ventricular end-diastolic volume index was similar between the 2 groups during follow-up (pretreatment: 77+/-19 ml/m(2) vs 74+/-13 ml/m(2), p=0.54; follow-up: 86+/-22 ml/m(2) vs 83+/-18 ml/m(2), p=0.60). These data suggest that IABP enhances the improvement in LVEF independent of remodeling in AMI patients with persistent ST elevation after revascularization.

Intra-aortic balloon counterpulsation in the emergency department: a 7-year review and analysis of predictors of survival

BACKGROUND

Intra-aortic balloon pump (IABP) counterpulsation in cardiogenic shock (CS) is suggested as bridging therapy to definite emergency revascularization, heart transplantation and acute valvular repair. Data concerning the use of IABP counterpulsation in an emergency department (ED) are rare.

PATIENTS AND METHODS

We reviewed retrospectively the charts of patients who had been treated by IABP counterpulsation in the ED of a tertiary care university hospital during a 7-year period. We analyzed indications for IABP treatment, complications of IABP use and studied various predictors for 30-day survival.

RESULTS

Overall 88 (68 male) patients, median age 60 years (IQR 53-69 years) were treated with IABP counterpulsation. CS was caused by acute coronary syndrome (ACS), acute cardiomyopathy decompensation of (CMP) and aortic stenosis (AS) in 77 (87%), ten (12%) and one (1%) patients, respectively. Complications attributed to the insertion or maintenance of IABP were observed in nine (10%) patients. Thirty four patients (38%; 24 male) survived. Compared to non-survivors, these patients were younger (56 vs. 63 years; P<0.023) and had significant lower serum lactate levels before IABP insertion (3 vs. 5.5 mmol/l; P<0.002). Logistic regression analysis identified age (P<0.04) and serum lactate serum level before IABP (P<0.01) as independent predictors for survival. In the 77 patients with ACS PTCA tended to be associated with a higher rate of survival (P<0.09).

CONCLUSION

Initiation of IABP counterpulsation in patients with CS in an ED appears safe. Low levels of serum lactate and younger age were independent predictors of survival. In patients with ACS PTCA may contribute to improved outcome.

The use of intra-aortic balloon counterpulsation in patients with cardiogenic shock complicating acute myocardial infarction: data from the National Registry of Myocardial Infarction 2

BACKGROUND

Cardiogenic shock complicating acute myocardial infarction (AMI) remains the leading cause of death in patients hospitalized with AMI. Although several studies have demonstrated the importance of establishing and maintaining a patent infarct-related artery, it remains unclear as to whether intra-aortic balloon counterpulsation (IABP) provides incremental benefit to reperfusion therapy. The purpose of this study was to determine whether IABP use is associated with lower in-hospital mortality rates in patients with AMI complicated by cardiogenic shock in a large AMI registry.

METHODS

We evaluated patients participating in the National Registry of Myocardial Infarction 2 who had cardiogenic shock at initial examination or in whom cardiogenic shock developed during hospitalization (n = 23,180).

RESULTS

The mean age of patients in the study was 72 years, 54% were men, and the majority were white. The overall mortality rate in all patients who had cardiogenic shock or in whom cardiogenic shock developed was 70%. IABP was used in 7268 (31%) patients. IABP use was associated with a significant reduction in mortality rates in patients who received thrombolytic therapy (67% vs 49%) but was not associated with any benefit in patients treated with primary angioplasty (45% vs 47%). In a multivariate model, the use of IABP in conjunction with thrombolytic therapy decreased the odds of death by 18% (odds ratio, 0.82; 95% confidence interval, 0.72 to 0.93).

CONCLUSIONS

Patients with AMI complicated by cardiogenic shock may have substantial benefit from IABP when used in combination with thrombolytic therapy.

Acute descending aortomyoplasty induces coronary blood flow augmentation

BACKGROUND

Aortomyoplasty is a procedure aimed to improve cardiac output in patients suffering from heart failure. Stimulation of the latissimus dorsi muscle around the aorta produces hemodynamic effects similar to those of the intraaortic balloon pump. These may be maintained without the accompanying complications or the need for anticoagulation. The objective of this study was to test the acute effects of aortomyoplasty on coronary artery blood flow.

METHODS

Eight mongrel dogs (18 to 30 kg) underwent acute descending aortomyoplasty. Several stimulation protocols were applied after wrapping of the latissimus dorsi muscle around the aorta in different surgical configurations. The left anterior descending coronary blood flow was measured using a transonic Doppler flow probe. Left ventricular and aortic pressures, proximal and distal to the aortomyoplasty site, were monitored continuously.

RESULTS

Significant aortic diastolic pressure augmentation was expressed both as an increase in peak values, from 110 +/- 24 mm Hg to 120 +/- 24 mm Hg (p < 0.001) and as an increase in the diastolic integral, from 64 +/- 23 mm Hg x s to 84 +/- 37 mm Hg x s (p < 0.001). Concomitantly, peak left anterior descending coronary blood flow increased from 26 +/- 10 mL/min to 32 +/- 12 mL/min (p < 0.001). This was associated with an increase in the diastolic flow integral from 11 +/- 4 mL to 14 +/- 6 mL (p < 0.001).

CONCLUSIONS

Descending aortomyoplasty induces significant augmentation of coronary blood flow. Optimal timing of muscle stimulation is important in achieving the best assist. This procedure may prove beneficial for end-stage ischemic patients.

Hemodynamic effects of new intra-aortic balloon counterpulsation timing methods in patients: a multicenter evaluation

BACKGROUND

To test whether later intra-aortic balloon pump (IABP) deflation approaching or simultaneous with left ventricular ejection would improve hemodynamics and myocardial efficiency with the use of new balloon deflation methods, 4 IABP timing techniques were evaluated in 43 patients.

METHODS AND RESULTS

Later balloon deflation produced significantly greater percentage changes in mean aortic pressure (6% vs 1%), systolic pressure time index (-27% vs -20%), diastolic pressure time index (35% vs 19%), and the systolic pressure-time index/diastolic pressure-time index ratio (97% vs 51%), respectively. However, these changes increased peak systolic pressure (-15% vs -11%). Cardiac output and stroke volume indexes were not significantly altered over the 4 settings.

CONCLUSIONS

These data suggest that systemic hemodynamics and myocardial efficiency may be improved by later balloon deflation approaching left ventricular ejection in comparison to conventional IABP timing.

Regional effects of aortomyoplasty in acute ischemia

BACKGROUND

Aortomyoplasty is a technique for achieving autogenous diastolic counterpulsation. This experiment was designed to determine if aortomyoplasty using conditioned latissimus dorsi muscle could improve regional myocardial function during coronary ischemia.

METHODS

Six mongrel dogs underwent a staged operation in which the left latissimus dorsi was conditioned in situ for 4 weeks, then wrapped around the descending aorta and stimulated during diastole with each cardiac contraction. Regional ischemia was caused by occlusion of the left anterior descending coronary artery. Regional function was measured with somomicrometry in the region of ischemia and in a control area. An intraaortic balloon pump was inserted for comparison with aortomyoplasty performance.

RESULTS

Coronary artery occlusion caused a significant decrease in the percentage of regional shortening (14.2 +/- 7.9 to -2.2 +/- 4.0; p = 0.001) and thickening (11.9 +/- 4.6 to -5.8 +/- 3.3; p < 0.001). Aortomyoplasty improved regional motion in both percentage shortening (-2.2 +/- 4.0 to 2.3 +/- 3.7; p = 0.008) and thickening (-5.8 +/- 3.3 to 2.8 +/- 1.9; p < 0.001). The intraaortic balloon pump also improved percentage shortening (-3.7 +/- 2.0 to 0.7 +/- 1.9; p = 0.01) and thickening (-5.0 +/- 2.8 to 2.4 +/- 3.8; p < 0.001), and was not significantly different than aortomyoplasty.

CONCLUSIONS

These data show that aortomyoplasty has beneficial effects on ischemic left ventricular contractility, and may therefore be useful for treating inoperable coronary artery disease.

Short-term effects of intra-aortic balloon pumping on renal blood flow and renal oxygen consumption in cardiogenic shock

Intra-aortic balloon pumping is frequently used in patients with cardiogenic shock when oliguria persists despite maximal pharmacologic support. The objective of this study was to measure the effect of intra-aortic balloon pumping on renal blood flow, renal oxygen delivery, and renal oxygen consumption in such patients. Central hemodynamics, renal blood flow, and oxygen transport were measured in 10 patients in low cardiac output states. Measurements were made with and without intra-aortic balloon counterpulsation. Renal blood flow was measured by continuous renal vein thermodilution. Small improvements were observed in cardiac output (3.1 +/- 0.8 vs 3.5 +/- 0.8 L/min, P < .01) and pulmonary capillary wedge pressure (22 +/- 5.6 vs 19 +/- 5.3 mmHg, P < .05), but mean arterial blood pressure was unchanged (69 +/- 11 vs 69 +/- 5 mmHg, not significant). Baseline renal blood flow was reduced to approximately 37%, renal oxygen delivery to 31%, and renal oxygen consumption to 60% of normal values. No significant improvement was seen in single-kidney renal blood flow (184 +/- 108 vs 193 +/- 107 mL/min), renal oxygen delivery (28 +/- 16 vs 30 +/- 16 mL/min), or renal oxygen consumption (4.9 +/- 2.0 vs 4.7 +/- 2.5 mL/min) in response to 1:1 counterpulsation. In comparison with measurements made during short-term suspension of counterpulsation, 1:1 aortic balloon pumping failed to result in an increase in renal blood flow, oxygen delivery, or oxygen consumption from the low levels observed in these patients.

The use of intraaortic balloon counterpulsation in acute myocardial infarction and high risk coronary angioplasty

Patients with complex coronary arterial stenoses, decreased ejection fraction, or acute myocardial infarction are at increased risk during percutaneous coronary interventions. Intraaortic balloon counterpulsation (IABP) can provide benefit in such cases by several mechanisms. Myocardial perfusion is improved and left ventricular afterload is reduced by balloon counterpulsation. Patients with cardiogenic shock clearly benefit from balloon counterpulsation until revascularization can be performed. Recent studies have documented the utility of balloon counterpulsation in patients undergoing angioplasty as treatment for an acute myocardial infarction. Balloon counterpulsation is also an effective means to reduce ischemia and provide hemodynamic support during complex percutaneous coronary interventions. This review will summarize the benefits, indications, and complications of balloon counterpulsation during acute myocardial infarction and high-risk coronary angioplasty.

Hemodynamic, mechanical, and metabolic determinants of thrombolytic efficacy: a theoretic framework for assessing the limitations of thrombolysis in patients with cardiogenic shock

Although thrombolytic therapy has been shown to limit infarct size, preserve left ventricular function, and improve survival in most subgroups of patients with acute MI, a benefit has not been demonstrated in patients with clinical left ventricular dysfunction or overt cardiogenic shock before treatment is initiated. The reason(s) for the lack of benefit derived from thrombolytic therapy in these settings is unclear. Left ventricular dysfunction and overt cardiogenic shock are the result of extensive myocardial necrosis, typically in excess of 30% of the left ventricle, which progresses over time. The available data suggest that thrombolytic efficacy is decreased because of either hemodynamic, mechanical, or metabolic factors. As a result coronary patency is rarely achieved in a timely fashion, and if patency is achieved it typically is not maintained. The ability of mechanical revascularization by means of balloon angioplasty to reduce mortality suggests that reperfusion is a key determinant of outcome even among patients with large infarctions and early signs of left ventricular dysfunction. Thrombolytic therapy, which is widely available and extensively tested, represents the standard of care for patients with acute MI. Its apparent lack of efficacy in patients with congestive heart failure and cardiogenic shock is poorly understood. Further investigation must therefore be undertaken.

Augmentation of coronary blood flow by intra-aortic balloon pumping in patients after coronary angioplasty

BACKGROUND

Controversy exists regarding the ability of intra-aortic balloon pumping to increase coronary blood flow in patients with obstructive coronary artery disease. To assess the effects of intra-aortic balloon pumping on coronary hemodynamics, we measured coronary blood flow velocity with a 0.018-in. Doppler-tipped angioplasty guide wire in 15 patients who received an intra-aortic balloon pump for typical clinical indications.

METHODS AND RESULTS

Intra-aortic balloon pumping augmented diastolic pressure 83 +/- 35%. In nine patients before angioplasty, peak diastolic coronary flow velocity beyond the stenosis (mean diameter narrowing, 95 +/- 7%) was 5.3 +/- 9.6 cm/sec and was unaffected by intra-aortic balloon pumping. After angioplasty, the improved coronary luminal diameter narrowing (n = 12; mean narrowing, 18 +/- 12%) was associated with increased distal diastolic flow velocity integral and peak diastolic and mean velocities (13.3 +/- 8.4 units: 36.4 +/- 18.3 and 24.0 +/- 11.4 cm/sec, respectively; all p < 0.01 versus before angioplasty), which were further augmented (36 +/- 37%, 54 +/- 49%, and 26 +/- 17%, respectively; all p < 0.01) with intra-aortic balloon pumping. Intra-aortic balloon pumping did not significantly increase the distal systolic velocity integral (10 +/- 59%) or peak systolic velocity (3 +/- 33%). Similar degrees of balloon pump augmentation of distal coronary flow velocity values were observed in five angiographically normal reference arteries in four patients.

CONCLUSIONS

These data demonstrate lack of significant flow improvement beyond most critical stenoses with intra-aortic balloon pumping and the unequivocal restoration and intra-aortic balloon pump-mediated augmentation of both proximal and distal coronary blood flow velocities after amelioration of severe coronary obstructions in patients after successful coronary angioplasty.

Enhanced coronary blood flow velocity during intraaortic balloon counterpulsation in critically ill patients

OBJECTIVES

The aim of this study was to assess coronary blood flow during intraaortic balloon counterpulsation by direct measurement.

BACKGROUND

In a majority of human studies, increased coronary blood flow during intraaortic balloon counterpulsation measured by indirect techniques has not been consistently demonstrated.

METHODS

Hemodynamic variables and coronary blood flow velocity (20-MHz Doppler-tipped catheter) data were measured in 19 patients requiring intraaortic balloon pumping for clinical indications (11 patients had acute myocardial infarction [9 with shock], 6 had unstable angina, 1 had acute mitral regurgitation and 1 was at high risk undergoing angioplasty). Hemodynamic data, mean and phasic diastolic flow velocity and velocity-time integrals (computed from digitized waveforms) were analyzed during periods of 1:1 balloon counterpulsation.

RESULTS

Intraaortic balloon pumping decreased systolic pressure (6 +/- 10%, p < 0.001) and increased diastolic pressure (80 +/- 30% from baseline, p < 0.001) without changing RR interval. Peak phasic, mean coronary flow velocity and diastolic flow velocity integral were significantly increased (115 +/- 115%, 67 +/- 61%, 103 +/- 81%, respectively, all p < 0.001) during intraaortic balloon pumping. In addition, although a wide splay of data was evident due to operator set variations in balloon inflation and deflation timing, the greater increases in diastolic flow velocity integral (DFVi) occurred in patients with basal systolic pressure < or = 90 mm Hg (% delta DFVi = 102 - 0.1.[unaugmented systolic pressure], SEE = 21.7 mm Hg, r = 0.30, p < 0.001).

CONCLUSIONS

Intraaortic balloon pumping unequivocally and significantly augments proximal coronary blood flow velocity, nearly doubling the coronary flow velocity integral in most patients. This mechanism may be a significant means of ischemia relief in hypotensive patients.

Effects of intraaortic balloon pumping on coronary hemodynamics after coronary angioplasty in patients with acute myocardial infarction

It has been reported that intraaortic balloon pumping can prevent reocclusion after coronary angioplasty for acute myocardial infarction. The speculated mechanism has been the production of markedly enhanced diastolic coronary perfusion pressure; however, most studies have reported that intraaortic balloon pumping has little effect on coronary blood flow. To assess the effectiveness of this procedure, we studied 12 patients with acute anterior myocardial infarction who were undergoing coronary angioplasty and intraaortic balloon pumping. After successful angioplasty, coronary blood flow velocity was measured with a coronary Doppler catheter before and during intraaortic balloon pumping. Although mean coronary blood flow velocity was unchanged, intraaortic balloon pumping increased peak coronary blood flow velocity from 34.6 +/- 5.0 cm/sec (mean +/- SEM) to 46.7 +/- 5.8 cm/sec (p < 0.005). Such an increase in peak coronary blood flow velocity seemed to be a mechanism by which intraaortic balloon pumping could prevent reocclusion after coronary angioplasty for acute myocardial infarction.

Observations of coronary flow augmentation and balloon function during intraaortic balloon counterpulsation using transesophageal echocardiography

The intraaortic balloon pump has been shown to decrease myocardial oxygen demand by afterload reduction, while increasing myocardial oxygen supply by diastolic augmentation of coronary blood flow. This diastolic augmentation of coronary flow has been demonstrated experimentally with invasive methods. Noninvasively, transesophageal echocardiography has demonstrated efficacy in enabling visualization of the proximal left coronary artery and in recording coronary blood flow velocity. To assess the potential of this technique in demonstrating quantitatively the increase in coronary flow during counterpulsation, 6 patients were studied during intermittent balloon pumping. Peak diastolic coronary blood flow velocity increased by a mean of 117% (range 62 to 287) during balloon inflation (p = 0.002). Furthermore, coronary flow velocity integral increased by a mean of 87% (range 43 to 176; p = 0.003). Problems associated with intraaortic balloon pumping were discovered by transesophageal echocardiography in 4 patients (incorrect balloon placement, damage to the aortic wall [2 patients], and premature balloon deflation time). Transesophageal echocardiography can be used in evaluating intraaortic balloon positioning within the aorta and in monitoring coronary artery flow augmentation during counterpulsation. This relatively noninvasive technique adds another dimension to the evaluation of balloon function and may help in optimizing the benefits of counterpulsation.

Cardiogenic shock after acute myocardial infarction. Incidence and mortality from a community-wide perspective, 1975 to 1988

BACKGROUND

Cardiogenic shock resulting from acute myocardial infarction is a serious complication with a high mortality rate, but little is known about whether its incidence or outcome has changed over time. As part of an ongoing population-based study of acute myocardial infarction, we examined trends over time in the incidence and mortality rate of cardiogenic shock after acute myocardial infarction.

METHODS

We studied 4762 patients with acute myocardial infarction who were admitted to 16 hospitals in the Worcester, Massachusetts, metropolitan area between 1975 and 1988. We determined the incidence of and short-term and long-term mortality due to cardiogenic shock in each of six years during this study period.

RESULTS

The incidence of cardiogenic shock complicating acute myocardial infarction remained relatively constant, averaging 7.5 percent. Multivariate regression analysis that controlled for variables affecting incidence revealed significant though inconsistent temporal trends in the incidence of cardiogenic shock. As compared with the risk in 1975, the adjusted relative risk (with 95 percent confidence interval) was 0.83 (0.54 to 1.28) in 1978, 0.96 (0.63 to 1.48) in 1981, 0.68 (0.42 to 1.12) in 1984, 1.16 (0.70 to 1.92) in 1986, and 1.65 (0.99 to 2.77) in 1988. The overall in-hospital mortality rate among patients with cardiogenic shock was significantly higher than that among patients without this complication (77.7 percent vs. 13.5 percent, P less than 0.001). The in-hospital mortality among the patients with shock did not improve between 1975 (73.7 percent) and 1988 (81.7 percent). Long-term survival during the 14-year follow-up period was significantly worse among patients who survived cardiogenic shock during hospitalization than among patients who did not have shock (P less than 0.001).

CONCLUSIONS

The results of this observational, community-wide study suggest that neither the incidence nor the prognosis of cardiogenic shock resulting from acute myocardial infarction has improved over time. Both in-hospital and long-term survival remain poor for patients with this complication.

Intraaortic balloon pumping as the postangioplasty strategy in acute myocardial infarction

To assess the usefulness of intraaortic balloon pumping (IABP) in acute myocardial infarction (AMI), 114 patients with anterior AMI undergoing emergency percutaneous transluminal coronary angioplasty (PTCA) for total occlusion of the left anterior descending artery were studied. After successful PTCA 66 patients were treated with conventional therapy (group I), and 48 patients were treated with IABP for 25 +/- 8 hours (group II). The reocclusion rate was significantly lower in group II (2.4% vs 17.7% p less than 0.05). An increase in ejection fraction in group II compared with group I was marginally significant (4.5 +/- 12.2% vs 9.2 +/- 13.0%, p = 0.08). Vascular complications occurred in two patients, but there were no deaths from IABP. These results suggest that after successful PTCA for acute myocardial infarction, IABP prevents reocclusion and may add strength to reperfusion in the improvement of left ventricular function.