Clinical and hemodynamic results of intraortic balloon counterpulsation and surgery for cardiogenic shock

A review of cardiogenic shock in acute myocardial infarction

Cardiogenic shock continues to be the most common cause of death in patients hospitalized with acute myocardial infarction. It has also been frequently associated with ST-segment elevation myocardial infarction (STEMI) and patients with co-morbidities. Cardiogenic shock presents with low systolic blood pressure and clinical signs of hypoperfusion. Rapid diagnosis and supportive therapy in the form of medications, airway support and intra-aortic balloon counterpulsation is required. Initial stabilization can be followed by reperfusion by fibrinolytic therapy, emergent percutaneous intervention (PCI) or coronary artery bypass grafting (CABG). The latter two have been found to decrease mortality in the long term. Research is being carried out on the role of inflammatory mediators in the clinical manifestation of cardiogenic shock. Mechanical support devices also show promise in the future.

Cardiogenic shock: a historical perspective

Significant progress has been made over the past 60 years in defining and recognizing cardiogenic shock (CS), and there have been tremendous advances in the care of patients who have this illness. Although there are many causes of this condition, acute myocardial infarction with loss of a large amount of functioning myocardium is the most frequent cause. It was recognized early in the study of CS that prompt diagnosis and rapid initiation of therapy could improve the prognosis, and this remains true today. Although the mortality from CS remains high, especially in elderly populations, modern therapies improve the chance of survival from this critical illness.

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.

Cardiogenic shock complicating acute coronary syndromes

Cardiogenic shock remains the major cause of death among patients with all types of acute coronary syndromes. Thus, there is a growing interest in the identification of patients who are at risk for developing cardiogenic shock, in the exploration of different therapeutic approaches to preventing its development, and in the improvement of outcome when it occurs. This article reviews the aetiology and pathophysiology of cardiogenic shock, its epidemiology, its treatment (including pharmaceutical agents, counterpulsation, and revascularisation), and its outcome. Algorithms are presented that predict its occurrence in both ST-segment-elevation myocardial infarction and unstable angina or non-ST-elevation myocardial infarction, and that predict its mortality in patients with ST-segment-elevation acute myocardial infarction. Such new areas as metabolic therapy and glycoprotein IIb/IIIa inhibitors are discussed, as are the economic implications of shock.

Association Between Serial Measures of Systemic Blood Pressure and Early Coronary Arterial Perfusion Status Following Intravenous Thrombolytic Therapy

Background: Systemic hypotension, at times transient while in other instances more prolonged, is common among patients with myocardial infarction (MI). It also is a characteristic feature for patients experiencing either advanced congestive heart failure or cardiogenic shock. In this group of patients, thrombolytic therapy has failed to exert. favorable impact on their high in-hospital mortality. Although it has been postulated that the success of thrombolytic therapy is directly linked to systemic blood pressure' there is little information available in human subjects. Methods and Results: In a University of Massachusetts Thrombolysis Data Bank Study, 127 patients with MI who were given intravenous thrombolytic therapy (tPA or streptokinase) within 6 hours from symptom onset (4.2 +/- 1.5 hours) had serial systemic blood pressure measurements (at the time of hospital arrival, treatment initiation, and every 30 minutes during the thrombolytic infusion) and underwent coronary angiography within 120 minutes of treatment initiation. All patients received intravenous heparin and oral aspirin. By univariate analysis, disastolic blood pressure below 80 mmHg at the time of treatment initiation was associated with a reduced angiographic coronary perfusion grade [Thrombolysis in Myocardial Infarction (TIMI) flow grade; p + 0.02]. A correlation analysis of tPA-treated patients indicated that a greater maximum change in diastolic blood pressure during treatment correlated inversely with coronary perfusion (r +.24, p < 0.05). By multivariate regression analysis, however, only shorter time to treatment (p + 0.001) and thrombolysis with tPA (p + 0.02) were independent predictors of coronary arterial perfusion grade. Conclusion: Systemic blood pressure (and presumably proximal coronary arterial perfusion pressure) in the ranges investigated in this study is not an independent predictor of coronary reperfusion following intravenous thrombolytic therapy with either tPA or streptokinase. It seems likely, therefore, that properties intrinsic to the ruptured plaque and occlusive thrombus, and potentially the local metabolic environment, either alone or acting synergistically with perfusion pressure, are determinants of thrombolytic success. Further investigation of factors influencing the efficacy of thrombolysis should be undertaken.

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.

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.

Percutaneous transluminal coronary angioplasty in patients with cardiogenic shock

In cardiogenic shock complicating acute myocardial infarction, percutaneous transluminal coronary angioplasty has been reported to significantly improve the modest survival benefits afforded by emergency surgical revascularization and thrombolytic therapy. The records of all patients who underwent angioplasty for acute myocardial infarction complicated by cardiogenic shock were retrospectively reviewed to determine whether coronary angioplasty improves survival. Of the 45 patients, 28 (group 1, 62%) had successful dilation of the infarct-related artery and 17 (group 2, 38%) had unsuccessful angioplasty. The groups were similar in extent of coronary artery disease, infarct location, incidence of multivessel disease and hemodynamic variables. The overall hospital survival rate was 56% (71% in group 1 and 29% in group 2). Group 1 patients had more left main coronary artery disease, and group 2 patients were older and had a higher incidence of prior myocardial infarction. Multivariate analysis showed that the survival advantage in patients with successful angioplasty was statistically significant (p = 0.014) when these factors were taken into account. At a mean follow-up interval of 2.3 years (range 1 month to 5.6 years), there were five deaths (four cardiac and one noncardiac), for a 2.3-year survival rate of 80% in patients surviving to hospital discharge. During the follow-up period, 36% of hospital survivors had repeat hospitalization for cardiac evaluation, 8% had myocardial infarction, 8% had coronary artery bypass surgery and 24% had angina.

Limitations of thrombolytic therapy for acute myocardial infarction complicated by congestive heart failure and cardiogenic shock

As many as one quarter of patients treated with thrombolytic therapy present with congestive heart failure or cardiogenic shock. Although thrombolytic therapy has been shown to limit infarct size, preserve left ventricular ejection fraction and decrease mortality in most subgroups of patients, no apparent benefit has been demonstrated in patients with clinical left ventricular dysfunction. The lack of correlation between ejection fraction and other measurements of left ventricular dysfunction such as exercise time, cardiac output, filling pressures, activation of the neurohumoral system and regional perfusion bed abnormalities may partly explain this paradox. Alternatively, lower perfusion rates, higher reocclusion rates, associated mechanical complications or completed infarction may explain these findings. Preliminary data indicate that emergency coronary angioplasty or bypass graft surgery improves survival in selected patients with cardiogenic shock. Because these findings suggest that restoration of infarct artery patency is especially important in patients with clinical left ventricular dysfunction, additional studies are needed in these patients to investigate the potential benefit that new thrombolytic strategies, inotropic or vasodilator agents or intraaortic balloon counterpulsation might offer by augmenting coronary blood flow and improving reperfusion rates. Currently, acute mechanical revascularization should be considered for patients who present with congestive heart failure associated with hypotension or tachycardia and for patients with cardiogenic shock.

The in-hospital development of cardiogenic shock after myocardial infarction: incidence, predictors of occurrence, outcome and prognostic factors. The MILIS Study Group

The incidence, outcome and predictors of the in-hospital development of cardiogenic shock and its prognostic significance were analyzed in 845 patients presenting with acute myocardial infarction. Cardiogenic shock developed after hospitalization in 60 patients (7.1%). In half of these patients, cardiogenic shock developed at least 24 h after hospital admission. The in-hospital mortality rate was greater than 15 times higher for patients with cardiogenic shock than for patients without shock (65.0% versus 4.3%, respectively, p less than 0.001). Enzymatic evidence of infarct extension occurred in 23.3% of the patients with shock compared with 7.4% of those without shock (p less than 0.0001). Multivariate analysis indicated that independent predictors for the in-hospital development of cardiogenic shock were age greater than 65 years (p = 0.007), left ventricular ejection fraction on hospital admission less than 35% (p = 0.007), large infarct as estimated from serial enzyme determinations (that is, peak creatine kinase-MB isoenzyme greater than 160 IU/liter (p = 0.008), history of diabetes mellitus (p = 0.011) and previous myocardial infarction (p = 0.012). Patients with three, four or five of these risk factors had a 17.9%, 33.7% or 54.4% probability, respectively, of developing cardiogenic shock after hospital admission. Left ventricular function, as reflected by left ventricular ejection fraction (p = 0.04) and severity of left ventricular wall motion abnormality (p = 0.04), was the most important determinant of in-hospital mortality in the patients with cardiogenic shock.

Intraaortic balloon counterpulsation

The physiologic principle of hemodynamic circulatory support for the failing left ventricle must be directed toward reducing left ventricular work and myocardial oxygen demand and increasing myocardial oxygen supply. This support can best be accomplished with the use of intraaortic balloon counterpulsation. Support of the failing heart after cardiopulmonary bypass was the most frequent indication for counterpulsation treatment in our reported series. This type of assist was required in 5.2 percent of my patients. I reviewed the reports from three medical centers and added our own results in patients who required intraaortic balloon counterpulsation for weaning from cardiopulmonary bypass. Of a total of 399 patients, 255 or 73 percent were weaned off the balloon assist device and of this group, 239 or 60 percent were subsequently discharged from the hospital. Among patients who required intraaortic balloon counterpulsation for postoperative pump failure, 43 (70 percent) of 66 patients were weaned off the intraaortic balloon device, and 35 (53 percent) were later discharged from the hospital. A 24 percent survival rate occurred in patients with cardiogenic shock treated solely with counterpulsation; however, the survival rate increased to 52 percent when those patients subsequently received cardiac catheterization and appropriate surgical intervention.

Percutaneous intraaortic balloon counterpulsation. Clinical effectiveness and hazards

Because of its greater ease and rapidity of insertion, the percutaneous intraaortic balloon in many institutions has become the primary method for implementing counterpulsation. We report the results and complications of 113 attempted procedures in a variety of clinical settings. We had a high (93.8 percent) insertion success rate. However, our 18.6 complication rate was similar to the experience reported for the surgical method of insertion. Thus, the original anticipation of reduced complications with this method has not been realized in this and other recent reports.

Percutaneous intraaortic balloon pumping: initial experience

The necessity of surgical procedures for insertion as well as for removal of the balloon catheter remains a serious disadvantage of IABP. The percutaneous technique of insertion and removal of a specially designed balloon catheter is therefore of a great interest. Our initial clinical experience shows that this is simple, rapid and safe and can be performed at the bedside in a few minutes by any physician experienced with arterial catheterization. Its hemodynamic efficiency is identical. No specific complications were encountered although two cases of pulmonary embolism were recorded. A causal relationship between pulmonary embolism and the percutaneous removal of a balloon catheter must therefore be considered.

Two dimensional echocardiographic visualization of ventricular septal rupture after acute anterior myocardial infarction

In three consecutive cases of ventricular septal rupture after acute anterior myocardial infarction, wide angle two dimensional echocardiography readily visualized the septal defect, permitting the defect to be localized and its size estimated. In addition, negative contrast echoventriculography identified a left to right shunt at the ventricular level. The echocardiographic findings were corroborated by cardiac catheterization data in all patients, by perioperative examination in two and by postmortem findings in one patient. Postoperative echocardiographic studies afforded demonstration of the patch closing the defect. In patients with acute myocardial infarction associated with the sudden appearance of a systolic murmur, two dimensional echocardiography should be performed promptly in order to guide the diagnosis and management of these critically ill patients. In some patients with severe cardiogenic shock, in whom a favorable prognosis depends on rapid treatment, two dimensional echocardiography may allow the patient to be taken to surgery immediately without further study.

Quantitative indices of intra-aortic balloon pump (IABP) dependence during post-infarction cardiogenic shock

This study attempts to quantitate post-infarction cardiogenic shock IABP dependence in instances of massive myocardial infarction with the use of hemodynamic indices plotted over time-course trajectories. Mortality is predicted when age and hemodynamic performance are also considered. It appears that post-infarction IABP dependence can be quantitated and that such information can be useful in considering diagnostic and therapeutic alternatives during the course of IABP support and cardiogenic shock. The analysis suggests that such IABP-dependent patients could be considered for therapeutic alternatives. They do not expire during the first 50 hours of IABP support and neither improve nor deteriorate during the second 50 hours of support. They remain in Class B without the occurrence of life-threatening ventricular dysrhythmias for a sufficient time for cardiac catheterization to determine the appropriateness of corrective procedures.

Regional left ventricular function assessed by contrast angiography in acute myocardial infarction

The relationship of segmental left ventricular (LV) wall motion abnormalities to LV function 2-6 days after acute transmural myocardial infarction (MI) was investigated in 45 patients by quantitative contrast ventriculography. Patients were divided into four classes according to the MIRU criteria. Segmental wall motion was assessed by determining the percentage of systolic shortening (deltaS) along nine hemiaxes and the extent of akinetic or dyskinetic abnormally contracting segments (% ACS) expressed as a percentage of end-diastolic perimeter. When compared with that in 17 normal control-subjects, the LV end-diastolic volume was increased only in patients in class III and class IV; the LV end-systolic volume increased progressively from normal through class IV. Ejection fraction had a negative linear correlation with %ACS (r = 0.97). The size of ACS was larger in anterior (34 +/- 14%) than in inferior MIs (23 +/- 7%), resulting in greater LV dysfunction. However, for a comparable size of ACS, infarct location alone did not influence LV function parameters. In the noninfarcted zone, deltaS was increased when the size of ACS was less than 25% and reduced when the size of ACS was greater than 25%. Thus, the size of ACS is a major determinant of LV dysfunction in acute MI. The compensatory mechanisms operate either through an augmented mechanical function of residual myocardium when the infarct is small, or through the Frank-Starling mechanism when the infarct is large.

Arterial counterpulsation in severe refractory heart failure complicating acute myocardial infarction

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

Modification of intraaortic balloon catheter to permit introduction by cardiac catheterization techniques

Intraaortic balloon counterpulsation has been widely applied for treatment of left ventricular pump failure and intractable angina. However, its use has been limited by the difficulty of balloon insertion in some patients and vascular complications in others. An AVCO intraaortic balloon was modified by the addition of a central lumen to allow pressure monitoring, injection of contrast medium and passage of a guide wire. The device was successfully used in 15 of 16 patients, including 4 of 5 in whom attempts to place a standard balloon catheter had failed. No significant vascular complications occurred in any patient. The modified balloon catheter appears to increase the efficacy and safety of insertion and allows immediate and continuous monitoring of arterial pressure.

Mechanical circulatory assistance by intra-aortic balloon pumping for the treatment of cardiogenic shock

Although the shock state due to acute myocardial infarction may be reversed by IABP in 80 per cent of patients, 55 to 65 per cent remain balloon-dependent. Therefore some attempt to correct the underlying anatomic abnormalities (reversible ischaemic areas and/or mechanical defects) appears necessary if these patients are to survive. With IABP catheterization studies performed in these critically-ill patients are well tolerated. Myocardial depression after cardiopulmonary by-pass is often related to subendocardial ischaemia. The combination of IABP and surgery has resulted in survival of approximately 50 per cent of patients in cardiogenic shock secondary either to a mechanical defect complicating myocardial infarction or to open-heart surgery.

Posterior rupture of the interventricular septum after acute myocardial infarction: successful early surgical repair

A patient with a large posterior ventricular septal defect complicating an acute inferior myocardial infarction is reported. Because of medically intractable biventricular failure, temporary circulatory assistance was initiated using intraaortic balloon pumping. Emergency coronary angiography, ventriculography, and subsequent operation were carried out. Operative repair involved closure of the septal defect with the use of a Dacron patch, infarctectomy, and aortocoronary bypass grafting and resulted in long-term survival of the patient.