Ventricular compliance in ischemic right ventricular dysfunction

Effect of a reduced donor heart right ventricular distensibility on post-heart transplant haemodynamics

OBJECTIVES

This study aimed to investigate the characteristics of a reduced right ventricular distensibility after heart transplant.

METHODS

This study enrolled 64 adult patients who underwent heart transplant at our institution. The degree of right ventricular distensibility was quantified by calculating the difference between right atrial pressures (RAPs) of X descent and Y descent (X-Y) from the RAP waveform in right heart catheterization. Histologically, the ratio of the interstitial tissue in myocardial biopsy samples was calculated.

RESULTS

Of the 64 patients, 35 (55%) had a reduced right ventricular distensibility at 1 week after heart transplant (X-Y > 1 mmHg, RD group), and 29 (45%) had a normal right ventricular distensibility (X-Y ≤ 1 mmHg, ND group). The mean RAP and mean pulmonary capillary wedge pressure 1 week after heart transplant in the RD group were significantly higher than that in the ND group. The mean RAP and mean pulmonary capillary wedge pressure in the RD group gradually normalized 12 weeks postoperation. The ratio of the interstitial tissue of biopsy samples significantly correlated with the X-Y value. The number of patients who required inotropic support >14 days was higher in the RD group than in the ND group.

CONCLUSIONS

Reduced donor heart distensibility was a common impairment early after heart transplant. It might result from interstitial oedema in the myocardial tissue of the donor heart. Reduced donor heart distensibility after heart transplant might be associated with early clinical outcomes; however, further investigation is required.

Kussmaul's sign for the diagnosis of right ventricular myocardial infarction: a systematic review and meta-analysis of diagnostic test accuracy studies

INTRODUCTION

Kussmaul's sign, the absence of a drop in jugular venous pressure or a paradoxical increase in jugular venous pressure on inspiration, can be evaluated as an indicator of right ventricular myocardial infarction. Right ventricular myocardial infarction complicates 30-50% of inferior myocardial infarctions and is associated with increased mortality when compared to inferior myocardial infarction without right ventricular involvement. Early recognition allows maintenance of preload. We reviewed the diagnostic test accuracy studies for Kussmaul's sign for diagnosis of right ventricular myocardial infarction.

METHODS

We conducted a librarian-assisted search using PubMed, Medline, Embase, and the Cochrane database from 1965 to October 2019. Only English language restriction was imposed. We identified studies that assessed patients presenting to a hospital with a suspected myocardial infarction who underwent an assessment for Kussmaul's sign and a diagnostic test for right ventricular myocardial infarction. Four independent reviewers extracted data from relevant studies. Study quality was assessed using the QUADAS-2 tool. A bivariate random effects meta-analysis was performed.

RESULTS

We identified 122 studies; ten were selected for full review. Eight studies had comparable populations with a total of 469 consecutive patients admitted with acute inferior myocardial infarction and were included in the analysis. Prevalence of right ventricular myocardial infarction was 36% (confidence interval [CI] 95% 31.8-40.5). All reference standards were combined. Kussmaul's sign had a sensitivity of 62.5% (44.6, 77.5), specificity 90% (73.0, 96.8), negative likelihood ratio (LR) 0.2 (0.1-0.8) and positive LR 5.8 (2.5, 13.3).

CONCLUSION

In the presence of acute myocardial infarction, Kussmaul's sign is specific for acute right ventricular myocardial infarction and may serve as an important clinical sign of right ventricular dysfunction requiring preload preserving management.

Analytic Review: Right Ventricular Infarction

Right ventricular myocardial infarction (RVMI) usually occurs after occlusion of a dominant right coronary artery, and the amount of right ventricular necrosis depends on whether this occlusion occurs proximal or distal along the length of the coronary artery. In patients who have a considerable amount of right ventricular necrosis, the physical examination reveals an elevated jugular venous pressure and Kussmaul's sign. Acute hemodynamic monitoring demonstrates a disproportionate elevation of the right atrial pressure (RAP) when compared with the pulmonary artery wedge pressure (PAWP). Previously validated hemodynamic criteria for identifying hemodynamically important RVMI include an RAP greater than or equal to 10 mm Hg and a RAP: PAWP ratio greater than or equal to 0.8. These hemodynamic findings can be seen in approximately 10% of patients who are seen with acute inferior transmural myocardial infarction; the findings can be produced in another 10% of patients after volume loading.

Radionuclide angiography accurately assesses right ventricular systolic function using either the first pass or equilibrium technique. When the right ventricular ejection fraction is less than 40% and there is evidence of right ventricular wall motion abnormalities, the presence of hemodynamically important RVMI is highly likely. When a patient presents with hypotension and low cardiac index, volume therapy should be instituted initially. However, if cardiac index does not improve after RAP and PAWP have increased to greater than 20% above control values, intravenous dobutamine should be instituted without delay to restore circulatory stability. The acute and long-term prognosis of patients with RVMI is excellent as long as extensive left ventricular necrosis does not occur concomitantly. Furthermore, right ventricular systolic function has been shown to improve significantly in the recovery period so that the patient's functional capacity is not imparied.

Pulmonary Artery Catheters: An Update

Pulmonary artery (PA) catheters are widely used in the care of the critically ill. Numerous catheter designs are available, and the list of indications for their use is con stantly expanding. Extensive physiological data are sup plied by catheters. Right atrial, right ventricular, PA, and PA wedge pressure waveforms, as well as cardiac output and several derived parameters (e.g., systemic vascular resistance, pulmonary vascular resistance) are easily measured. Clinical application of these data may aid in diagnosis and management of acutely ill patients. Physi cians using catheters need to be aware of the numerous complications associated with their use. Scrupulous at tention to insertion and maintenance techniques will minimize the incidence of many of these complications. The undefined risk/benefit ratio of PA catheterization has caused controversy among physicians. Prospective studies to define better the risks versus benefits of PA catheters are currently being planned. Physicians using PA catheters should recognize that the catheters have no direct therapeutic benefit and that PA catheterization should neither replace bedside clinical evaluation nor delay treatment of the patient.

Determinants of the Y Descent and its Usefulness as a Predictor of Ventricular Filling

Our objective was to determine if the magnitude of the Y descent in the central venous pressure tracing could be used to determine which patients have restrictive hemodynamics. To better understand the determinants of the Y descent, we also examined the effects of changes in blood volume, changes in pleural pressure, and respiratory maneuvers on its magnitude. Studies were performed in both humans and dogs. In six anesthetized dogs, we examined the effect on the Y descent in central venous pressure (CVP) of an infusion of normal saline, a decrease in pleural pressure produced by having animals perform a Mueller maneuver, and the combination of a Mueller maneuver and volume loading. Observations were made with the chest closed, chest open, and chest and pericardium open. The state of the chest did not effect the Y descent. The Y descent was only significantly increased when a Mueller maneuver was combined with volume loading. There was a significant inverse relationship between the magnitude of the decrease in esophageal pressure and the Y descent. There was also a linear relationship between the CVP and Y descent. For the human studies, we examined patients undergoing routine cardiac surgery. They were examined during spontaneous breathing before intubation, with positive pressure breathing and closed chest, with positive pressure breathing and open chest, with an open pericardium, with a closed chest and positive pressure breathing postsurgery, and with spontaneous breathing after extubation following surgery. The Y descent was greater in spontaneous breaths postsurgery compared to before surgery, and this was associated with an increase in CVP. However, the magnitude of CVP did not correlate with the magnitude of the Y descent. A restrictive pattern in cardiac filling was identified by a lack of respiratory variation in right atrial pressure during spontaneous breaths. All patients with large Y descents had a restrictive pattern, but many patients with restrictive filling patterns did not have a large Y descent. The magnitude of the Y descent is affected by the volume status, the magnitude and direction of the changes in pleural pressure, and the compliance of the pericardial compartment. A large Y descent indicates a restrictive cardiac state, but a small Y descent does not rule out a restrictive condition because of the many interacting variables.

Right ventricular infarction--diagnosis and treatment

Right ventricular infarction (RVI) as assessed by various diagnostic methods accompanies inferior-posterior wall myocardial infarction (MI) in 30 to 50% of patients. Recognition of the syndrome of RVI is important as it defines a significant clinical entity, which is associated with considerable immediate morbidity and mortality and has a well-delineated set of priorities for its management. Patients may clinically present with hypotension, elevated jugular venous pulse (JVP), and occasionally shock, all in the presence of clear lung fields. The ST-segment elevation of > or = 0.1 mV in the right precordial leads V4R is a readily available electrocardiographic sign used for diagnosis of RVI. Other diagnostic approaches for assessing RVI include echocardiography, radionuclide ventriculography, technetium pyrophosphate scanning, and hemodynamic measurements. The proper management of RVI includes volume loading to maintain adequate right ventricular preload, ionotropic support, and maintenance of atrioventricular synchrony. Reperfusion therapy should be initiated at the earliest signs of right ventricular dysfunction. Finally, complete recovery over a period of weeks to months is a rule in a majority of patients, suggesting right ventricular "stunning" rather than irreversible necrosis has occurred.

Pathophysiology and management of right heart ischemia

Acute right coronary artery occlusion proximal to the right ventricular (RV) branches results in right ventricular free wall dysfunction, exerting mechanically disadvantageous effects on biventricular performance. Depressed RV systolic function decreases transpulmonary delivery of left ventricular (LV) preload, resulting in diminished cardiac output. The ischemic right ventricle is stiff, dilated, and volume dependent, resulting in pandiastolic RV dysfunction and septally mediated alterations in LV compliance, which are exacerbated by elevated intrapericardial pressure. Under these conditions, RV pressure generation and output are dependent on LV-septal contractile contributions, governed by both primary septal contraction and paradoxical septal motion. When the culprit coronary lesion is distal to the right atrial (RA) branches, augmented RA contractility enhances RV performance and optimizes cardiac output. Conversely, more proximal occlusions result in ischemic depression of RA contractility, which impairs RV filling and performance, resulting in more severe hemodynamic compromise. Bradyarrhythmias limit output generated by the rate-dependent noncompliant ventricles. Hemodynamic compromise may respond to volume resuscitation and restoration of physiologic rhythm. Vasodilators and diuretics should generally be avoided. In some patients, parenteral inotropic stimulation may be required. The right ventricle appears to be relatively resistant to infarction and recovers even after prolonged occlusion. The term RV "infarction" appears to be somewhat of a misnomer, for in most patients acute RV dysfunction represents ischemic but predominantly viable myocardium. Although RV performance improves spontaneously even in the absence of reperfusion, recovery of function may be slow and associated with high in-hospital mortality. Reperfusion enhances recovery of RV performance and improves the clinical course and survival.

Right heart ischemia: pathophysiology, natural history, and clinical management

Right ventricular (RV) ischemia occurs in 50% of patients with acute inferior myocardial infarction, and may result in severe hemodynamic compromise associated with poor clinical outcome. Acute right coronary artery (RCA) occlusion proximal to the RV branches results in right ventricular free wall (RVFW) dysfunction. The ischemic, dyskinetic RVFW exerts mechanically disadvantageous effects on biventricular performance. Depressed RV systolic function leads to a decrease in transpulmonary delivery of left ventricular (LV) preload, resulting in diminished cardiac output. The ischemic right ventricle is stiff, dilated, and volume dependent, resulting in pandiastolic RV dysfunction and septally-mediated alterations in LV compliance, which are exacerbated by elevated intrapericardial pressure. Under these conditions, RV pressure generation and output are dependent on LV-septal contractile contributions, governed by both primary septal contraction and paradoxical septal motion. When the culprit coronary lesion is distal to the right atrial (RA) branches, augmented RA contractility enhances RV performance and optimizes cardiac output. Conversely, more proximal occlusions result in ischemic depression of RA contractility, which impairs RV filling, thereby resulting in further depression of RV performance and more severe hemodynamic compromise. Bradyarrhythmias limit the output generated by the rate-dependent noncompliant ventricles. Patients with right ventricular infarction and hemodynamic compromise often respond to volume resuscitation and restoration of a physiological rhythm. Vasodilators and diuretics should generally be avoided. In some, parenteral inotropic stimulation may be required. The right ventricle appears to be relatively resistant to infarction and has a remarkable ability to recover even after prolonged occlusion. Therefore, the term RV infarction appears to be somewhat of a misnomer, for in most patients a substantial proportion of acute RV dysfunction represents ischemic but viable myocardium. Although RV performance improves spontaneously even in the absence of reperfusion, recovery of function may be slow and associated with high in-hospital mortality. Reperfusion enhances the recovery of RV performance and improves the clinical course and survival of patients with ischemic RV dysfunction.

In-hospital outcome of elderly patients with acute inferior myocardial infarction and right ventricular involvement

BACKGROUND

There are some specific high-risk subgroups of patients with acute inferior myocardial infarction, such as older patients and those with right ventricular involvement. However, the clinical implications of right ventricular infarction in elderly subjects have not been studied previously.

METHODS AND RESULTS

To determine the clinical impact of right ventricular involvement in elderly patients with inferior myocardial infarction, we studied the in-hospital outcome of 198 consecutive patients > or = 75 years of age with a first acute inferior myocardial infarction according to the presence of ECG or echocardiographic criteria of right ventricular infarction. In patients with right ventricular involvement (41%), in-hospital case fatality rate was 47% (mainly because of nonreversible low cardiac output cardiogenic shock) compared with 10% in patients without right ventricular involvement (P<.001). Patients with right ventricular involvement also had a significantly higher incidence of cardiogenic shock (32% versus 5%), which was independent of left ventricular ejection fraction, complete AV block (33% versus 9%), and interventricular septal rupture (9% versus 0%). After adjustment for age, sex, diabetes, shock on admission, left ventricular systolic dysfunction, and complete AV block, right ventricular infarction remained a powerful independent predictor of in-hospital death (adjusted odds ratio, 4.0; 95% confidence interval, 1.3 to 14.2).

CONCLUSIONS

Elderly patients with acute inferior myocardial infarction have a substantially increased risk of death during hospitalization when right ventricular involvement is present. The poorer outcome is due mainly to the high incidence of cardiogenic shock and its infrequent reversibility.

Jugular venous pressure and pulse wave form in the diagnosis of right ventricular infarction

Jugular venous pressure (measured clinically) and pulse wave form (recorded at 100 mm/s) were analysed in 44 cases of first acute myocardial infarction and 10 age-matched controls. Patients were divided into different groups according to site of infarction decided by detailed 2-D echocardiography. Raised jugular venous pressure had high specificity (96.8%) but low sensitivity (39%) in diagnosing right ventricular infarction. Positive Kussmaul's sign had equal specificity but lower sensitivity (26.1%). Rapid 'y' descent had high specificity (100%) but low sensitivity (17.3%) in diagnosing right ventricular infarction. Jugular venous pressure and pulse wave form are significantly affected by the magnitude of damage to interventricular septum and left ventricular free wall.

Pulmonary blood flow profiles with reduced right ventricular function in lambs

The determinants of right ventricular (RV) performance with damaged RV free wall, such as occurs with RV infarction, are still unclear. Using 20-MHz Doppler ultrasound equipment, we investigated the changes in pulmonary blood flow velocity profiles before and after ligation of the right coronary artery. RV dp/dt, stroke volume, RV stroke work, aortic pressure and cardiac output decreased and central venous pressure rose after the ligation. The RV stroke work-end-diastolic pressure relationship indicated impaired RV function following ligation. We observed shortened acceleration time (65.0 +/- 15.1 vs 54.4 +/- 6.2 ms, P < 0.05) and reduced maximum velocity of forward flow (59.0 +/- 5.9 vs 52.5 +/- 7.6 cm/s, P < 0.05) after the ligation. Acceleration was interrupted earlier after ligation than before ligation. These alterations in flow are thought to be a consequence of the altered movement of the RV free wall and ventricular septum induced by RV infarction.

Right-to-left flow through a patent foramen ovale in acute right ventricular infarction. Two case reports and a proposal for management

Right-to-left shunting through a foramen ovale complicating acute right ventricular infarction and resulting in severe arterial hypoxemia has been described eight times before. Treatment strategies have often aimed at reducing the shunt. Four patients died. Less attention has been paid to attempts at revascularization and, despite a high incidence of atrioventricular conduction disturbances, to temporary dual-chamber pacing. We describe herein two patients with postcardiac surgical right ventricular infarction complicated by severe right-to-left interatrial shunting. Treatment strategy was aimed at improving right ventricular function, and right-to-left shunting ceased. All efforts should be directed at treating right ventricular dysfunction, which is the cause of the clinical picture, and not at reducing the shunt, which is a secondary phenomenon.

Hemodynamic criteria for diagnosis of right ventricular ischemia associated with inferior wall left ventricular acute myocardial infarction

To test the diagnostic value of different hemodynamic indexes for the diagnosis of acute right ventricular (RV) ischemic dysfunction, we studied 2 groups of consecutive patients admitted for an acute left ventricular inferior wall myocardial infarction: 51 patients with (group 1) and 32 patients without (group 2) RV ischemia as determined by coronary angiography. In both groups, we analyzed by right-sided cardiac catheterization right-sided heart pressures, pulmonary capillary wedge pressure, and cardiac index. We also calculated pressure ratios (mean right atrial pressure or RV end-diastolic over pulmonary capillary wedge pressures), pulmonary vascular resistance, and RV stroke work index. We found significant differences (p < 0.01) between the 2 groups when comparing mean right atrial pressure, RV end-diastolic pressure, ratio of these 2 pressures over pulmonary capillary wedge pressure, RV stroke work index, and right atrial and RV pressure waveforms. The best combined sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were found for the right atrial M or W waveform pattern, isolated or combined with a disproportionate elevation of RV end-diastolic over pulmonary capillary wedge pressures (respectively, 92%, 94%, 90%, 87%, and 89%). Volume loading was performed in 27 patients (18 with and 9 without RV ischemia). Right heart pressures and RV stroke work index increased significantly and similarly in both groups. Cardiac index increased significantly only in patients without RV ischemia (p = 0.02). However, volume loading did not significantly modify the diagnostic value of the different hemodynamic criteria studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Relations between Doppler tracings of pulmonary regurgitation and invasive hemodynamics in acute right ventricular infarction complicating inferior wall left ventricular infarction

To test the hypothesis that flow characteristics from pulmonary regurgitation (PR) can predict right ventricular (RV) involvement in patients with inferior wall acute myocardial infarction, we prospectively recorded continuous-wave Doppler tracings and right-sided cardiac hemodynamics in 48 consecutive patients with inferior wall acute myocardial infarction and PR. Right heart hemodynamics enabled the identification of 29 patients with (group 1) and 19 without (group 2) RV involvement. In patients with RV involvement, the pulmonary regurgitant flow pattern was characterized by a rapid rise in flow velocity to a peak level followed by an abrupt deceleration in mid-diastole, whereas in patients without RV involvement, the deceleration in mid-diastole was gradual. The pressure half-time of PR (PHTPR) and the lowest mid-diastolic to peak early diastolic velocity ratio were significantly lower in group 1 than in group 2 (91 +/- 31 vs 214 +/- 57 ms [p < 0.001], 0.35 +/- 0.08 vs 0.59 +/- 0.13 [p < 0.001], respectively). The best diagnostic accuracy (95%) was obtained with cut-off values of PHTPR < or = 150 ms and the lowest mid-diastolic to peak early diastolic velocity ratio < or = 0.5: sensitivity 100%, specificity 89%, positive predictive value 94%, and negative predictive value 100%. Using multiple logistic regression analysis, we found that PHTPR was the strongest predictor of RV involvement. Thus, these parameters, derived from pulmonary regurgitant tracings, are useful in the noninvasive bedside diagnosis of RV infarction.

Radionuclide assessment of right ventricular contractile reserve after acute myocardial infarction

Conflicting data have been reported about the implications of a decreased right ventricular (RV) contractile reserve (i.e., a < 5% stress-induced increase in ejection fraction [EF]). If a reduced reserve corresponds to ischemia, it will probably be associated with an electrocardiographic marker of RV ischemia, stress-induced ST-segment elevation (increases ST) in leads V3R to V6R. To test this hypothesis, 98 asymptomatic postinfarction patients (27 with RV infarction) were assigned to a dobutamine stress test (maximal dose 40 micrograms/kg/min) with equilibrium radionuclide angiography and electrocardiographic study, including leads V3R to V6R. All but 11 patients underwent coronary angiography. A dobutamine-induced increases ST in VR leads was seen in 24 patients with and in 8 without RV infarction. This electrocardiographic sign was 75% sensitive and 84% specific for the diagnosis of proximal right coronary artery disease. It was 61% sensitive and 74% specific for the detection of reduced RV contractile reserve. Patients with RV infarction had reduced RVEF at rest (38 +/- 9%), but the mean contractile reserve was normal (12 +/- 12%). The contractile reserve was significantly smaller in patients with proximal versus distal or no right coronary artery disease. It was also smaller (P < 0.01) in patients with increased ST versus no increased ST. In conclusion, high doses of dobutamine are useful in assessing RV contractile reserve after acute myocardial infarction. In these patients, a reduced RV contractile reserve is related to proximal right coronary artery disease and is associated with stress-induced increased ST in VR leads.

Ischemia right ventricular dysfunction

For many years ischemic heart disease involving the right ventricle had received little attention. During the last 15 years, the initial works of Cohn, Isner, and others spawned a number of clinical and experimental studies that extended the understanding of the pathophysiology of ischemia in the right ventricle. Most of the work has been done in the setting of acute myocardial infarction, and information is still lacking in other conditions, such as chronic ischemic heart disease and perioperative right ventricular dysfunction. Acute right ventricular infarction rarely occurs in the absence of left ventricular necrosis and in most cases is the extension of an inferior left ventricular infarct. The majority of patients with right ventricular infarction only exhibit subtle signs of ischemic dysfunction. Elevated right atrial pressure is found only in the typical syndrome of elevated venous pressure; low output syndrome can be found only in 20% of the cases, and cardiogenic shock secondary to right ventricular necrosis is found only in 10%. It is also important to note that there is not a clear correlation between the severity of ischemic right ventricular dysfunction and the necrotic area. The discrepancy may be due to ischemia without necrosis of the right ventricular wall (stunned myocardium), but the intact pericardium and the necrosis of the interventricular septum may also play an important role. In the most severe form of ischemic right ventricular dysfunction, the entire right ventricular wall is akinetic. Right atrial, right ventricular, and pulmonary artery pressures become similar in magnitude and shape, and the pulmonary valve is opened during diastole, demonstrating a passive blood flow from the right atrium to the left ventricle through the low resistance pulmonary capillary bed. Volume loading, administration of dopamine or dobutamine, and careful use of vasodilators under hemodynamic monitoring are the therapeutic measures to control the severe forms of acute ischemic right ventricular dysfunction. The use of thrombolytic agents has decreased the incidence of right ventricular dysfunction after acute myocardial infarction. Mortality is high in the severe forms of acute ischemic right ventricular dysfunction, but after discharge from hospital the prognosis is good and right heart failure is unusual, even in those patients with shock during the first days of evolution of the infarct.

Right ventricular infarction

Right ventricular infarction complicates up to half of inferior left ventricular infarctions. The term represents a spectrum of disease from mild, asymptomatic right ventricular dysfunction to cardiogenic shock, and it includes transient ischemic myocardial dysfunction as well as myocardial necrosis. Right ventricular infarction is associated with considerable morbidity and mortality, and its presence defines a high-risk subgroup of patients with inferior left ventricular infarction. Diagnosis of this condition requires a high degree of suspicion based on clinical findings and the early recording of the electrocardiogram through right precordial leads, as well as elevated right-sided filling pressures out of proportion to left-sided filling pressures. The proper management of right ventricular infarction requires sustaining adequate right ventricular preload with volume loading and maintenance of atrioventricular synchrony, reduction of right ventricular afterload (particularly when left ventricular dysfunction is present), and inotropic support of the right ventricle. Early reperfusion with fibrinolytic therapy or direct angioplasty is also warranted. Survivors of right ventricular infarction generally have a restoration of normal right ventricular function with resolution of hemodynamic abnormalities.

Effects of acute, transient coronary occlusion on global and regional right ventricular function in humans

OBJECTIVES

The aim of this study was to investigate the changes in right ventricular function during acute coronary occlusion produced by inflating a coronary angioplasty balloon catheter.

BACKGROUND

Alterations in right ventricular function are well known to occur in patients with acute myocardial infarction or ischemic cardiomyopathy. However, the changes in right ventricular function resulting from acute, transient coronary occlusion of each of the major coronary arteries have been scantily studied, perhaps because of serious limitations of currently available technology.

METHODS

A newly designed, mobile, multiwire gamma camera, in combination with generator-produced tantalum-178, affords high count rate first-pass radionuclide angiography and is thus ideal for studying right ventricular function at the bedside. Accordingly, 46 patients underwent first-pass radionuclide angiography at baseline and during transient coronary occlusion induced by a coronary angioplasty balloon catheter.

RESULTS

A significant, albeit modest, decrease in global right ventricular ejection fraction occurred during occlusion of the left anterior descending (from 42.9 +/- 9.3% to 39 +/- 8.7%, p < 0.05) and left circumflex (from 44 +/- 9.1% to 38.8 +/- 7.9%, p = 0.03) coronary arteries, but diagonal artery occlusion caused no significant change in right ventricular ejection fraction. Occlusion of the right coronary artery proximal (but not distal) to the acute marginal branch caused a significant decrease in right ventricular ejection fraction (from 42.6 +/- 4.7% to 35.7 +/- 7.2%, p < 0.01). Although occlusion of the left anterior descending, left circumflex and proximal right coronary arteries all caused significant deterioration in regional right ventricular function, only proximal right coronary occlusion caused right ventricular dilation (p < 0.005).

CONCLUSIONS

Significant impairment of right ventricular function occurs during transient occlusion of the left anterior descending, left circumflex and proximal right coronary arteries, but only occlusion of the latter causes acute right ventricular dilation, probably as a result of ischemia.

Diagnosis of right ventricular acute myocardial infarction by dual isotope thallium-201 and indium-111 antimyosin SPECT imaging

To assess the diagnostic value of indium-111 antimyosin for detecting right ventricular (RV) wall acute infarction, 30 patients with electrocardiographic-documented left ventricular inferior (posterior) wall acute myocardial infarction underwent simultaneous dual isotope indium-111 antimyosin and thallium-201 single-photon emission computed tomography (SPECT) within 2 days of admission. RV necrosis was defined as uptake of indium-111 antimyosin anterior and to the right of septal thallium uptake. Twenty-nine of the 30 patients (97%) had indium-111 antimyosin uptake in the inferior, posterior or lateral walls of the left ventricle and 14 of 30 (47%) had additional RV antimyosin uptake. Three different patterns of RV uptake of indium-111 antimyosin were observed: crescent-shaped, focal and apical. Twenty-seven patients underwent gated blood pool scanning before hospital discharge. Twelve of the 14 patients with RV antimyosin uptake had gated blood pool scintigraphy and 7 of 12 had RV dysfunction; 5 had normal RV function. Except for 1 patient who had questionable RV antimyosin uptake and had RV dysfunction, no patient without RV antimyosin uptake had RV dysfunction. In summary, right and left ventricular necrosis can be detected on tomographic images of indium-111 antimyosin uptake in patients with inferior infarctions when simultaneous uptake of a perfusion tracer, thallium-201, is imaged and used as an aid to reconstruction and anatomic localization.

Stress-induced ST segment shift in leads V3R and V4R after acute myocardial infarction

A total of 107 patients with acute myocardial infarction underwent a dobutamine stress test and received increasing doses of the drug (5, 10, 15, 20, and up to 40 micrograms/kg/min). Coronary angiography was performed within the first month. The 12 conventional ECG leads plus the right chest leads V3R and V4R were recorded under basal conditions and after each dose of dobutamine. In 51 patients (group A) there was an ST shift greater than or equal to 0.5 mm in the right chest leads, with two different patterns: rightward (V2 less than V1 less than V3R V less than V4R) (n = 26) and leftward (V2 less than V1 less than V3R greater than V4R) (n = 25). In 56 patients (group B) no ST shift in the right chest leads was induced. An ST segment elevation greater than or equal to 0.5 mm in V4R was 43% sensitive and 86% specific for the detection of proximal right coronary artery disease. Four subgroups were established in group A: A1R, rightward ST elevation (n = 23); A1L, leftward ST elevation (n = 12); A2R, rightward ST depression (n = 3); and A2L, leftward ST depression (n = 13). Group A1R had predominantly inferior infarcts and right coronary artery stenoses, group A1L had predominantly anterior infarcts and left anterior descending coronary stenoses, and group A2L had posteroinferior infarcts and right or left circumflex stenoses, all of them with low sensitivity (less than 50%) and high specificity (greater than 87%) for a such diagnosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Optimal right ventricular filling pressures and the role of pericardial constraint in right ventricular infarction in dogs

BACKGROUND

Previous studies have reported an important role for right ventricular function in the pathophysiology of the low cardiac output state that can accompany right ventricular infarction. Some studies have suggested that right ventricular distensibility impairs right ventricular filling and stroke output; others have demonstrated that the pericardium can mediate depressed left ventricular filling and stroke output.

METHODS AND RESULTS

To determine the role of pericardial constraint and optimal volume loading in an experimental model of right ventricular wall infarction, six mongrel dogs were studied before and after right ventricular wall infarction and after volume loading. The pericardium was then opened in two phases. In the first phase, the pericardium was opened partially to allow the atria to distend freely, and in the second phase, the pericardium was opened completely. The animals were preinstrumented with two sets of piezoelectric crystals attached to the right ventricular free wall, one in the infarct and the other in the noninfarct territory. Left ventricular size was estimated by left ventricular crystals on the anterior wall of the left ventricle. Right ventricular and left ventricular Millar catheters were used to assess intracavitary pressure, and a flat balloon was used to assess intrapericardial pressure. Right ventricular infarction reduced cardiac output by 23% and stroke volume by 30%. End-diastolic segment length and transmural pressure of the left ventricle decreased. Volume loading restored cardiac output to baseline values and was mediated by a significant increase in end-diastolic length in the noninfarct territory. This was achieved by increasing right ventricular end-diastolic pressure from 9 +/- 2 to 16 +/- 3 mm Hg (p less than 0.01). Partial opening of the pericardium mediated significant increases in both end-diastolic segment lengths of the left ventricle and the noninfarct territory. Left ventricular end-diastolic pressure decreased slightly by 3 mm Hg (p = NS). Complete opening of the pericardium increased cardiac output and stroke volume and mediated a significant decrease in right and left ventricular end-diastolic pressures. Left ventricular transmural pressure and end-diastolic segment lengths of the left ventricle and the noninfarct territory increased. Left ventricular diastolic pressure-segment length relations were shifted upward by right ventricular infarction. A partial opening of the pericardium shifted this relation downward in all animals, and complete opening of the pericardium shifted the relation rightward and further downward.

CONCLUSIONS

Cardiac output is restored to baseline values by volume loading sufficient to increase the right ventricular diastolic pressure to 16 +/- 3 mm Hg. Evidence of pericardial constraint was observed and appears to be mediated by an atrioventricular interaction in addition to the direct ventricular interaction.

Determinants of hemodynamic compromise with severe right ventricular infarction

To elucidate determinants of hemodynamic compromise in patients with acute right ventricular (RV) infarction, we studied 16 patients with hemodynamically severe RV infarction by right heart catheterization and two-dimensional ultrasound. Severe RV systolic dysfunction, evident by ultrasound in all patients as RV dilatation and depressed RV free wall motion, was associated with a broad sluggish RV waveform, diminished peak RV systolic pressure (27.6 +/- 4.5 mm Hg), and depressed RV stroke work (4.6 +/- 2.4 g.m/m2). Paradoxical septal motion was consistently noted. In some cases, the septum bulged into the right ventricle in a pistonlike fashion and appeared to mediate systolic ventricular interaction through which left ventricular septal contraction contributed to RV pressure generation. RV diastolic dysfunction was indicated by elevated RV end-diastolic pressures (13.7 +/- 2.7 mm Hg), RV "dip and plateau," equalization of diastolic filling pressures, and reversal of diastolic septal curvature toward the volume-deprived left ventricle. A prominent right atrial (RA) X and blunted Y descent, indicative of impairment of RV filling throughout diastole, were confirmed in all patients by their relation to RV systolic events. Patients manifested one of two distinct RA waveform morphologies differentiated by A wave amplitude and associated with disparate clinical courses. In eight patients, an RA W pattern was evident, characterized by augmented A waves; eight others manifested an M pattern constituted by depressed A waves. Compared with those with an M pattern, patients with a W pattern had higher peak RV pressures (29.6 +/- 3.8 versus 25.5 +/- 4.3 mm Hg, p less than 0.05), better cardiac output (3.4 +/- 0.3 versus 2.9 +/- 0.7 l/min, p less than 0.05), more favorable response to volume and inotropes, and less frequently required emergency revascularization for refractory shock (none versus five for those with an M pattern). Patients with a W pattern were more severely compromised if atrioventricular dyssynchrony developed and were more dramatically improved by restoration of physiological rhythm. Angiography in patients with depressed A waves demonstrated more proximal coronary obstruction leading to ischemic compromise of RA function, whereas in those with augmented A waves, the culprit lesion was proximal to the RV but distal to the RA branches. These results indicate that hemodynamic compromise in patients with RV infarction is exacerbated by decreased preload reserve that is dependent on atrial systole. The amplitude of the RA A wave, an indication of the status of RA function, is an important determinant of RV performance and hemodynamic compromise.

Effect of opening the pericardium on right ventricular hemodynamics during cardiac surgery

The impact of the pericardium on right ventricular performance in the presence of normal filling pressures was evaluated using a rapid response RVEF thermodilution pulmonary artery catheter and TEE. In eight patients with normal right coronary arteries undergoing coronary artery bypass surgery, hemodynamic measurements revealed increased right ventricular end-diastolic and end-systolic volumes with diminished RVEF after opening the pericardium. In eight additional patients with right coronary artery disease, directionally similar changes in right ventricular volume were seen. Ejection fraction, however, was unchanged possibly due to altered right ventricular compliance. Echocardiogram evaluation of right ventricular area changes in patients with compromised right coronary systems corresponded to ejection fraction determinations obtained with thermodilution technique.

Hemodynamic importance of systolic ventricular interaction, augmented right atrial contractility and atrioventricular synchrony in acute right ventricular dysfunction

To delineate the determinants of right ventricular performance with acute right ventricular dysfunction, surgical electrical isolation of the right ventricular free wall was produced in 13 dogs. During atrioventricular (AV) pacing, hemodynamic and wall motion measurements were normal. When not paced, the right ventricular free wall became asystolic, resulting in a depressed and bifid right ventricular systolic pressure (33 +/- 5 to 18 +/- 4 mm Hg) and decreased left ventricular systolic pressure (100 +/- 18 to 80 +/- 18 mm Hg) and stroke volume (14 +/- 4 to 10.3 +/- 3.5 ml) (all p less than 0.05). Ultrasound demonstrated right ventricular free wall dyskinesia, increased right ventricular end-diastolic size (155 +/- 13% of control), but decreased left ventricular size (69 +/- 11% of control) (both p less than 0.05). Right atrial pressure increased (5.8 +/- 2.5 to 7.6 +/- 2.8 mm Hg, p less than 0.05) with an augmented A wave and blunted Y descent, indicating pandiastolic right ventricular dysfunction. The septum demonstrated reversed curvature in diastole and bulged paradoxically into the right ventricle during early systole, generating the initial peak of right ventricular pressure and reducing its volume. Later, posterior septal motion coincided with maximal left ventricular pressure and the second peak of the right ventricular waveform. Left ventricular pacing alone led to further decreases in right ventricular systolic pressure and size, left ventricular systolic pressure and stroke volume. The previously augmented A wave was replaced by a prominent V wave. Therefore, when contractility of its free wall is acutely depressed, right ventricular performance is dependent on left ventricular-septal contractile contributions transmitted by the septum.(ABSTRACT TRUNCATED AT 250 WORDS)

Right ventricular infarction

Right ventricular infarction commonly occurs in association with acute inferior left ventricular infarction, but is uncommon when infarction involves other areas of the left ventricle. Evidence of right ventricular infarction often can be detected by physical examination, electrocardiography, echocardiography, or radionuclide ventriculography. However, hemodynamically significant infarction (i.e., hypotension or shock) is much less frequent, occurring in approximately 10% of patients with other evidence of right ventricular infarction. Right ventricular infarction increases ventricular stiffness, thereby impeding diastolic filling. This results in hemodynamic changes similar to those found in constrictive pericarditis: elevated systemic venous pressure, a Y descent greater than the X descent, and an inspiratory increase in venous pressure. The increase in venous pressure generally equals or even exceeds left atrial pressure. When hypotension or shock occurs, expansion of vascular volume is generally employed as initial therapy. In nonresponders, dobutamine or similar inotropic agents may be helpful. The prognosis during the acute phases is guarded, but, in survivors, prognosis is favorable and generally related to the extent of left ventricular involvement.

Inversion of the normal interatrial septum convexity in acute myocardial infarction: incidence, clinical relevance and prognostic significance

Inversion of the normal interatrial septum convexity has been described in patients with right atrial pressure or volume overload, but there is no reference to this abnormality in acute myocardial infarction. A group of 576 consecutive patients with acute infarction and serial echocardiographic studies were prospectively evaluated during a mean follow-up period of 406 days. Inverted interatrial septum convexity was found in 30 patients (5.2%); 29 of the 30 presented with inferior infarction with right ventricular involvement (29 [24.4%] of 119) and the remaining presented with cardiac tamponade secondary to heart rupture. The incidence of inverted interatrial septum convexity rapidly decreased, and after 3 months it was present in only five patients. All patients with inverted interatrial septum convexity had a right atrial pressure greater than or equal to pulmonary capillary pressure, a relation found in only 2 of 43 patients with right ventricular involvement and normal septal convexity. In patients with right ventricular infarction, right atrial pressure was higher in the presence of inverted septal convexity (15.9 +/- 4.1 versus 10.5 +/- 4.1 mm Hg, p less than 0.0001) and the incidence of hypotension (10 [34.4%] of 29 versus 15 [17.4%] of 90, p = 0.04) and third degree atrioventricular block (10 [34.4%] of 29 versus 11 [12.2%] of 90, p = 0.006) as well as the mortality rate after 3 months (9 [31%] of 29 versus 11 [12.2%] of 90, p = 0.04) were higher in the presence of inverted convexity than in patients with normal septal convexity.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial natriuretic factor in patients with right ventricular infarction

To determine the possible role of atrial natriuretic factor in right ventricular infarction, serial measurements of this hormone were performed in 21 patients with acute inferior myocardial infarction. All patients underwent enzymatic, electrocardiographic, echocardiographic and coronary arteriographic studies. Ten patients also had right heart hemodynamic measurements. Eight patients had evidence of an associated right ventricular infarction (Group I) and 13 patients did not (Group II). Enzymatically estimated infarct size, presence of left heart failure and arrhythmias were similar in both groups. Mean arterial pressure in Group I (72.1 +/- 4.4 mm Hg) was significantly lower (p = 0.02) than in Group II (89.5 +/- 4.6 mm Hg). Seven (88%) of the eight patients in Group I had elevated right atrial pressures and a higher incidence than Group II of prolonged hypotension (75%) and right ventricular dysfunction (75%) clinically and by echocardiography. Plasma atrial natriuretic factor levels (mean values +/- SEM in pg/ml) for days 1, 2, 3 and 7 after infarction were, respectively: 152 +/- 30, 165 +/- 48, 199 +/- 27 and 189 +/- 31 for Group I versus 55 +/- 9, 55 +/- 11, 61 +/- 13 and 77 +/- 20 for Group II. The difference between groups was significant for days 1 (p less than 0.05), 3 and 7 (p less than 0.01) and not significant for day 2 (p = 0.07). These findings show that atrial natriuretic factor elevation is part of the neurohumoral response to right ventricular infarction and are consistent with the hypothesis that atrial natriuretic factor may play a pathophysiologic role in the right ventricular infarct syndrome.

Diagnosis of constrictive pericarditis by pulsed Doppler echocardiography of the hepatic vein

The diagnostic value of hepatic venous flow patterns was evaluated for constrictive pericarditis by pulsed Doppler. A characteristic flow pattern was assumed to be associated with the well-known atrial pressure curve. Thirteen patients with constrictive pericarditis were compared to 13 control subjects and to 25 patients with right ventricular pressure overload including 13 patients with tricuspid regurgitation. The characteristic finding in constrictive pericarditis was a W-wave pattern of flow velocities in the dilated hepatic veins, with abrupt reversal of flow late in systole and diastole before the A wave (100% specificity, 68% sensitivity). This depends, however, on the absence of tricuspid regurgitation (for its systolic component) or fast sinus rhythm (for its diastolic component). Additional diagnostic markers were systolic deceleration time of forward flow (40 to 130 ms) and systolic integral of flow velocities (4.3 to -4.0 cm) (sensitivity and specificity greater than or equal to 92%). In the presence of tricuspid regurgitation, diastolic deceleration time less than 150 ms and diastolic integral of flow velocities less than 6 cm were useful diagnostic signs. If combined, these criteria had 100% sensitivity and specificity for the diagnosis. Thus, pulsed Doppler assessment of flow velocities in the hepatic vein facilitates the diagnosis of constrictive pericarditis in clinical routine, using an auxiliary site with unlimited diagnostic access to the characteristic flow velocity pattern, which reflects right atrial pressure curve and filling abnormalities.

Assessment of right ventricular function in acute inferior myocardial infarction using 133-xenon imaging

The detection of right ventricular dysfunction in acute inferior myocardial infarction is important because of its potentially serious consequences which may be remediable with the appropriate therapeutic manoeuvres. A technique has been developed to assess right ventricular function using 133-xenon. This technique was applied to 26 patients who had sustained an acute inferior myocardial infarction. Right ventricular ejection fractions ranged from 7-54%, mean 30 +/- 11%, which was significantly lower than values obtained from normal volunteers (n = 21), mean 43 +/- 5%, and patients with arteriographically proven coronary artery disease without previous myocardial infarction (n = 12), mean 39 +/- 9%, P less than 0.001, and P less than 0.001, respectively. In the patients with acute inferior myocardial infarction 18 patients (69%) had evidence of right ventricular dysfunction (right ventricular ejection fraction less than 35%). 13/26 patients (50%) had clinical evidence of right ventricular dysfunction with a mean right ventricular ejection fraction 26 +/- 11% (range 7-54%) which was significantly lower than the patients without evidence of right ventricular dysfunction, mean 35 +/- 9% (range 16-49%), P less than 0.001. The clinical signs had a sensitivity of 72% (13/18), a specificity of 87.5% (7/8) and a predictive accuracy of 76% (20/26) when compared to the imaging data.

IN CONCLUSION

(1) gated 133-xenon imaging provides a method for assessing right ventricular function in the setting of acute myocardial infarction; (2) a wide spectrum of right ventricular dysfunction occurs following inferior myocardial infarction which may not manifest itself clinically.

Beyond the wedge: clinical physiology and the Swan-Ganz catheter

The Swan-Ganz catheter was introduced into general clinical medicine in 1970 and quickly gained widespread use in the management of critically ill patients. The device offers highly sophisticated physiologic information; however, in many instances, only the wedge pressure and the cardiac output are utilized when managing acutely ill patients. The purpose of this review is to illustrate and explain the array of physiologic data available from the Swan-Ganz catheter in most circumstances. A basic understanding of the information that can be obtained with the Swan-Ganz catheter is quite useful in the diagnosis and management of a variety of cardiovascular disorders. In addition, the Swan-Ganz catheter can be a helpful tool for teaching cardiovascular pathophysiology.

Variable spectrum and prognostic implications of left and right ventricular ejection fractions in patients with and without clinical heart failure after acute myocardial infarction

To determine the spectrum and prognostic implications of left and right ventricular (LV and RV) ejection fractions (EFs) in acute myocardial infarction (AMI), radionuclide ventriculography was performed in 114 consecutive patients, admitted without (Killip class I, 78 patients) or with (killip class II, 36 patients) clinical signs of pulmonary congestion within 24 hours of onset of symptoms of a transmural AMI. Mean LVEF was significantly lower in patients in Killip class II than in those in class I (0.32 +/- 0.11 vs 0.46 +/- 0.15, p less than 0.001) and in patients with anterior than inferior AMI (0.34 +/- 0.11 vs 0.52 +/- 0.14, p less than 0.001). Of the 36 patients with a severely depressed (0.30 or less) LVEF, 15 (42%) were in Killip class I. Mean RVEF did not differ significantly between Killip class I and II patients (0.42 +/- 0.11 vs 0.40 +/- 0.12, difference not significant) but was significantly lower in patients with inferior than anterior AMI (0.38 +/- 0.09 vs 0.44 +/- 0.11, p = 0.005). In patients with inferior AMI, a depressed RVEF (0.38 or less) was associated with a normal LVEF in 30% and a depressed LVEF in 20%, whereas in those with anterior AMI, a depressed RVEF, observed in 25% of patients, occurred only in association with a depressed LVEF.(ABSTRACT TRUNCATED AT 250 WORDS)

Scintigraphically detected predominant right ventricular dysfunction in acute myocardial infarction: clinical and hemodynamic correlates and implications for therapy and prognosis

To determine the clinical and hemodynamic correlates as well as therapeutic and prognostic implications of predominant right ventricular dysfunction complicating acute myocardial infarction, 43 consecutive patients with scintigraphic evidence of right ventricular dyssynergy and a depressed right ventricular ejection fraction (less than 0.39) in association with normal or near normal left ventricular ejection fraction (greater than or equal to 0.45) were prospectively evaluated. All 43 patients had acute inferior infarction, forming 40% of patients with acute inferior infarction, and only eight (24%) had elevated jugular venous pressure on admission. On hemodynamic monitoring, 74% of patients had a depressed cardiac index (less than or equal to 2.5 liters/min per m2), averaging 2.0 +/- 0.05 for the group. Of these, 30% did not demonstrate previously described hemodynamic criteria of predominant right ventricular infarction (right atrial pressure greater than or equal to 10 mm Hg or right atrial to pulmonary capillary wedge pressure ratio greater than or equal to 0.8, or both). The left ventricular end-diastolic volume was reduced to 49 +/- 11 ml/m2 (n = 22) and correlated significantly with the stroke volume index (r = 0.82; p less than 0.0001) and cardiac index (r = 0.57; p = 0.005). The follow-up right ventricular ejection fraction, determined in 33 patients, showed an increase of 10% or greater in 26 (79%), increasing from a mean value of 0.30 +/- 0.06 to 0.40 +/- 0.09 (p less than 0.0001) without a significant overall change in the mean left ventricular ejection fraction (0.56 +/- 0.10 to 0.56 +/- 0.11, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

A prospective clinical, scintigraphic, angiographic and functional evaluation of patients after inferior myocardial infarction with and without right ventricular dysfunction

To elucidate the functional and prognostic significance of right ventricular dysfunction after acute inferior wall myocardial infarction, 74 consecutive patients with inferior infarction were prospectively evaluated with gated equilibrium blood pool imaging at rest, submaximal exercise thallium-201 scintigraphy and coronary angiography before hospital discharge. In addition, symptom-limited stress thallium-201 scintigraphy was performed in 61 patients at 3 months, and all patients were followed up clinically for 23 +/- 15 months. Utilizing predetermined radionuclide angiographic criteria, 47 patients (Group I) had normal right ventricular function, 12 patients (Group II) had mild to moderate dysfunction and 15 patients (Group III) had severe right ventricular dysfunction. There were no significant differences among the groups with regard to age, history of prior myocardial infarction, peak creatine kinase values, maximal Killip functional class, number or type of in-hospital complications, left ventricular ejection fraction, prevalence of multivessel disease or the distribution and severity of disease affecting the infarct-related vessel. Exercise tolerance as assessed by treadmill time, blood pressure-heart rate product and peak work load in METS was comparable among the three groups, both before hospital discharge and at 3 month follow-up. No differences in indicators of exercise-induced ischemia were noted among the groups, including the prevalence of redistribution thallium-201 defects, ST segment depression or symptoms of chest pain. Finally, cardiac mortality, reinfarction rate and the incidence of medically refractory angina pectoris were similar in the three groups. Thus, right ventricular dysfunction after acute inferior wall myocardial infarction does not appear to limit exercise tolerance or identify a subgroup of patients at higher risk for recurrent cardiac events.

Effect of coronary artery recanalization on right ventricular function in patients with acute myocardial infarction

The effects of coronary artery recanalization by intracoronary administration of streptokinase on left ventricular function during acute myocardial infarction have received increasing attention in recent years. Although myocardial dysfunction is often more pronounced in the right ventricle than in the left ventricle in patients with acute inferior wall myocardial infarction, the effect of coronary artery recanalization on right ventricular dysfunction has not been previously addressed. Accordingly, in this investigation, 54 patients who participated in a prospective, controlled, randomized trial of recanalization during acute myocardial infarction were studied. Among 30 patients with inferior wall infarction, 19 had right ventricular dysfunction on admission; 11 of these 19 had positive uptake of technetium-99m pyrophosphate in the right ventricle, indicative of right ventricular infarction. Patients with successful recanalization (n = 6) exhibited improved right ventricular ejection fraction from admission to day 10 (26 +/- 7 to 39 +/- 14%, p less than 0.03). However, control patients (n = 6) and patients who did not undergo recanalization (n = 7) also exhibited improvement (20 +/- 7 to 29 +/- 11% [p less than 0.02] and 30 +/- 8 to 40 +/- 6% [p less than 0.03], respectively). Improvement in several other variables of right ventricular dysfunction evolved at an equal rate with the ejection fraction changes. Patients with or without right ventricular infarction improved similarly. These data indicate that the right ventricular dysfunction commonly associated with inferior wall infarction is often transient, and improvement is the rule, irrespective of early recanalization of the "infarct vessel."

Characterization of the human right ventricular pressure-volume relation: effect of dobutamine and right coronary artery stenosis

Right ventricular function was assessed in 15 patients using right ventricular pressure-volume loops. Right ventricular pressure using a micromanometer-tipped catheter, thermodilution cardiac output and gated blood pool scintigrams were simultaneously obtained. To help isolate the right ventricle, a slant hole collimator was used. The measurements were repeated during dobutamine infusion, which was titrated so there was minimal change in systemic pressure and heart rate. The right ventricular pressure-volume loop resembles the usual left ventricular loop except that the isovolumic contraction phase is often not as distinct, and right-sided ejection may continue well beyond right ventricular peak systolic pressure. Systolic but not diastolic function improved with dobutamine administration. There was no significant difference in right ventricular systolic function (ejection fraction, stroke work index, stroke volume index and cardiac index) or in end-diastolic volume index between patients without (Group I) and with (Group II) significant right coronary artery stenosis. However, there was a small but significant difference in right ventricular end-diastolic pressure (5.3 +/- 2.5 and 8.1 +/- 1.8 mm Hg [p less than 0.05]) for Group I and II, respectively. Thus, the right ventricular pressure-volume loop can be used to graphically display right ventricular function and improvement in contractility with dobutamine. The right ventricular isovolumic contraction phase and ejection phase differ from those in the usual left ventricular loop. Although there was a small difference in right ventricular end-diastolic pressure in patients with and without right coronary artery stenosis, the right ventricular pressure-volume loop did not provide additional discriminatory information between these two groups of patients.

Ischemic cardiomyopathy

The term "ischemic cardiomyopathy" was used initially to describe a clinical syndrome that was indistinguishable from primary congestive cardiomyopathy but due to severe, diffuse coronary artery disease. The term has been expanded to include the larger category of myocardial disease secondary to coronary artery disease. Using this expanded definition, we have discussed the varied clinical presentations of congestive ischemic cardiomyopathy and restrictive ischemic cardiomyopathy (stiff heart syndrome and right ventricular infarction), and how the effects of ischemia on left ventricular systolic and diastolic performance may cause these varied presentations. The prognosis of any ischemic cardiomyopathy is related primarily to the degree of ventricular dysfunction and the extent of coronary artery disease. Therapy is aimed at preventing or ameliorating myocardial ischemia and halting the progression of, or even reversing, the deterioration in myocardial function.