Right ventricular systolic and diastolic function at rest in patients with coronary artery disease. Assessment with equilibrium radionuclide ventriculography

Right ventricular systolic and diastolic function was studied in patients with ischemic heart disease using equilibrium radionuclide ventriculography. In patients with inferior myocardial infarction and proximal right coronary lesions, the right ventricular ejection fraction (0.43 +/- 0.06, n = 10, mean +/- SD) and peak filling rate (1.7 +/- 0.4 EDV/sec) were lower than normals (0.57 +/- 0.07 and 2.7 +/- 0.4 EDV/sec, n = 10, p less than 0.001, respectively). In these patients, the right ventricular time to peak filling rate was longer than in normals (225 +/- 36 msec vs 136 +/- 45 msec, p less than 0.001), while the left ventricular ejection fraction remained normal. In patients with inferior myocardial infarction and distal right coronary lesions, the right ventricular ejection fraction, peak filling rate and time to peak filling rate were not different from those in normals. Even in patients with proximal right coronary lesions, the right ventricular ejection fraction was normal unless they had an inferior myocardial infarction. A decreased left ventricular ejection fraction and abnormal motion of the ventricular septum did not affect the right ventricular ejection fraction. The present results suggest that patients with an inferior myocardial infarction and proximal right coronary lesion often develop right ventricular systolic and diastolic dysfunction.     

Comparative effects of intracoronary fibrinolysis and conventional treatment of myocardial infarction

57 patients with a complete coronary thrombosis were treated by intracoronary fibrinolysis during the first 6 hours of inaugural myocardial infarction. The artery was revascularised in 37 cases (65 p. 100). Eleven patients had isolated stenosis of the left anterior descending artery and 16 patients isolated stenosis of the right coronary artery. These patients were compared with 27 other patients admitted between the 6th and 18th hours of primary myocardial infarction treated conventionally, in whom coronary angiography performed between the 14th and 21st day after infarction showed isolated left anterior descending disease in 14 cases (9 thromboses and 5 stenoses) and isolated right coronary disease in 13 cases (7 thromboses and 6 stenoses). The haemodynamic data and heart rates were identical in both groups during control coronary angiography between the 14th and the 21st days. Global left ventricular function and regional wall motion were studied by 30 degrees right anterior oblique ventriculography using the Stanford method before fibrinolysis in the first group and at the end of the 3rd week in both groups. In LAD, repermeabilisation by fibrinolysis, significant improvements were observed in ejection fraction (EF p. 100 = 42 +/- 9 vs 50.6 +/- 14 p. 100, p less than 0.05); fractional shortening of the hypokinetic segment (FS p. 100 = 4.5 +/- 4.6 vs 12.4 +/- 8.8 p. 100, p less than 0.001), and in the number of hypokinetic or akinetic segments (6.0 +/- 1.1 vs 4.2 +/- 2.1, p less than 0.05). Segmental and global left ventricular function was much poorer in the group treated conventionally at the 21st day (EF p. 100 = 44 +/- 11 p. 100, p less than 0.05; FS p.t100 = 5.8 +/- 9.7 p.t100, p less than 0.05; number of diseased segments: 6.0 +/- 1.4, p less than 0.01). On the other hand, the improvement was less marked in patients with inferior wall infarction; the results in the two groups were comparable.     

Right ventricular myocardial infarction in patients with chronic lung disease: possible role of right ventricular hypertrophy

To determine the relation between right ventricular hypertrophy and right ventricular myocardial infarction in patients with chronic lung disease, the records of 28 patients with chronic lung disease, inferior myocardial infarction and significant coronary artery disease (group I) and 20 patients with right ventricular hypertrophy, chronic lung disease without inferior myocardial infarction or significant coronary artery disease (group II) were reviewed. Chronic lung disease was diagnosed by clinical criteria, chest radiographs and pulmonary function tests. All patients had postmortem examinations. Patients in group I were classified into two subgroups: group Ia (without right ventricular hypertrophy) and group Ib (with right ventricular hypertrophy). Right ventricular wall thickness was 3.3 mm +/- 0.5 in group Ia, 6.0 mm +/- 1.1 in group Ib and 8.8 mm +/- 2.4 in group II (group Ia versus Ib, p less than 0.001; group Ia versus II, p less than 0.001; group Ib versus II, p less than 0.001). Eleven patients (78.6%) in group Ib (chronic lung disease with both right ventricular hypertrophy and inferior myocardial infarction) had right ventricular myocardial infarction compared with only 3 patients (21.9%) in group Ia (chronic lung disease without right ventricular hypertrophy and with inferior myocardial infarction) (p less than 0.008). Isolated right ventricular myocardial infarction occurred in four patients (20%) in group II (chronic lung disease with right ventricular hypertrophy, but without evidence of infarction of the left ventricle or significant coronary artery disease). There was no significant difference in the extent of anatomic coronary disease in groups Ia and Ib.(ABSTRACT TRUNCATED AT 250 WORDS)     

Involvement and function of the right ventricle in acute myocardial infarct. Hemodynamic, echocardiographic and angioscintigraphic correlations

To assess the acute effects of myocardial infarction on right ventricular function 22 patients were studied utilizing right heart catheterization, radionuclide angiography and two dimensional echocardiography. Thirteen patients had inferior myocardial infarction (Group I) and 9 anteroseptal or anterior (Group II). Hemodynamic findings suggesting right ventricular infarction were present in 3 patients of Group I. Mean radionuclide right ventricular ejection fraction was lower in inferior myocardial patients (38.2 +/- 7.6-Group I vs 50.3 +/- 11.4-Group II, p less than 0.005), while left ventricular ejection fraction in anteroseptal, and anterior myocardial infarction patients (36.8 +/- 10.5-Group II vs 55.9 +/- 7.6-Group I, p less than 0.001). Six patients in Group I presented a depressed radionuclide right ventricular ejection fraction (less than 40%): moreover right ventricular ejection fraction correlated with left ventricular ejection fraction in Group II (r = 0.79, p less than 0.001) but not in Group I (r = 0.55, p = NS). By mean of 2 dimensional echocardiography Group I patients had an increased right ventricular end diastolic area (15.3 +/- 3.8 vs 12.1 +/- 1.2 cm2, p less than 0.05) while Group II an increased right ventricular free wall motion (47.3 +/- 10.7 vs 32.4 +/- 14.1%, p less than 0.005); right ventricular end diastolic area correlated with right ventricular ejection fraction only in Group I (r = 0.60, p less than 0.05). Five patients in Group I and no patients in Group II had an enlarged right ventricular end diastolic area. Therefore, radionuclide and echocardiographic evidence of right ventricular involvement were not always associated with abnormal hemodynamics. Thus, the damaged right ventricular chamber dilates to allow an adequate stroke volume in presence of low ejection fraction; hemodynamic significant right ventricular myocardial infarction becomes evident only in patients with more severe right ventricular compromise; the increase in right ventricular free wall motion in anterior myocardial infarction patients compensates the loss of contribution of interventricular septum contraction.     

The effects of right ventricular involvement on heart rate variability and ventricular late potentials in acute inferior myocardial infarction

Depressed heart rate variability and presence of ventricular late potentials in acute myocardial infarction are associated with a poor prognosis. Although it is known that the abnormalities vary according to anterior or inferior location of acute myocardial infarction, the relationship with right ventricular acute myocardial infarction is not clear. The effects of right ventricular myocardial infarction on heart rate variability and ventricular late potentials are studied. The study was performed with a total of 46 patients (38 males; aged 56 +/-13 yr, range, 33 to 70 yr). Twenty-six patients had isolated inferior myocardial infarction while 20 patients had accompanying right ventricular involvement. For all patients, ambulatory Holter recordings between 24 and 48 hours following myocardial infarction, echocardiography in first 48 hours, and signal-averaged electrocardiography with submaximal exercise at average day 6 (range, 5 to 8 days) were performed. Heart rate variability and signal-averaged electrocardiography recordings were repeated after discharge (average, 39 days). During the first 24 to 48 hr, time domain parameters (SDNN1 and SD1) were significantly lower (SDNN1: 62 +/- 17 vs 100 +/- 20 ms, p = 0.001; SD: 37 +/- 10 vs 50 +/- 16 ms, p = 0.03) in patients with isolated inferior MI than in those with right ventricular involvement, whereas root-mean-square voltage (RMS-SD1) showed no significant difference in both groups (28 +/- 7 vs 35 +/- 8 ms). In post-discharge heart rate variability recordings, there were no significant differences (SDNN2: 86 +/- 13 vs 95 +/- 15 ms; SD2: 48 +/- 11 vs 57 +/- 13 ms; RMS-SD2: 32 +/- 14 vs 35 +/- 9 ms). In pre-discharge tests, the mean value of low-amplitude signals (LAS1) was higher (26 +/- 9 vs 33 +/- 11 ms, p = 0.03) in patients with isolated inferior myocardial infarction than in those with right ventricular involvement, while other signal-averaged electrocardiography parameters were not significantly different (filtered QRS: 102 +/- 5 vs 105 +/- 10 ms, RMS-40(1): 44 +/- 13 vs 26 +/- 10 microV; incidence of ventricular late potentials: 23% vs 30%, p = NS, respectively). In post-discharge tests, all of signal-averaged electrocardiography parameters were similar in both groups (filtered QRS2: 112 +/- 12 vs 114 +/- 8 ms, LAS2: 28 +/- 9 vs 32 +/- 13 ms, RMS-40(2): 36 +/- 10 vs 34 +/- 11 microV, and frequency of ventricular late potentials2: 23% vs 30%, p = NS). These data suggest that right ventricular involvement in an acute inferior myocardial infarction is associated with improved heart rate variability parameters but not ventricular late potentials in pre-discharge period. However, the influence of right ventricular involvement on heart rate variability parameters fades away in the post-discharge period.     

Significance of ST segment depression in the precordial leads during the acute phase of inferior myocardial infarction

Reciprocal changes of the ST segment in the acute phase of inferior myocardial infarction are common but their significance remain controversial. We studied this problem by comparing the ECG on admission of 83 patients with acute inferior myocardial infarction, with the clinical outcome and haemodynamic and angiographic data obtained on average 3 weeks after the onset of symptoms. Fifty nine patients (Group I) had ST depression greater than or equal to 1 mm in at least one of the leads V1 to V4; 24 patients (Group II) had no ST depression in this territory. The patients in Group I were older (59.6 +/- 6.4 vs 54 +/- 5.3 years, p less than 0.01), had higher total CPK (1 835 +/- 940 vs 875 +/- 305, p less than 0.01) and MB fractions (269 +/- 102 vs 95 +/- 35), more complications during the hospital period (80%, mainly haemodynamic vs 38%, p less than 0.01) and more severe left ventricular dysfunction: ejection fraction 52.2 +/- 6% vs 59.2 +/- 7%, p less than 0.05; cardiac index 2.75 +/- 0.4 l/min/m2 vs 3.25 +/- 0.3 l/min/m2, p less than 0.005). There was no difference in left ventricular wall motion between the groups on biplane angiography. However, coronary angiography showed left coronary disease to be more common in Group I (84%) than in Group II (37%), p less than 0.005. Left anterior descending and left circumflex disease was equally common. Patients with persistent ST depression after 48 hours had lower ejection fractions than those in whom it regressed within 48 hours.(ABSTRACT TRUNCATED AT 250 WORDS)     

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."     

Right ventricular ejection fraction in patients with acute anterior and inferior myocardial infarction assessed by radionuclide angiography

We measured right and left ventricular ejection fracttion (EF) from high frequency time-activity curves obtained during the initial passage of an intravenous bolus of 99mTc (Sn) pyrophosphate. In 22 normal controls right ventricular EF averaged 0.52 +/- 0.04 (SD). In 24 acute anterior or lateral infarction patients right ventricular EF was normal (0.56 +/- 0.10), while left ventricular EF was reduced (0.45 +/- 0.10, P less than 0.001 vs controls). In 19 acute inferior infarction patients left ventricular EF also was depressed (0.51 +/- 0.09, P less than 0.001 vs controls). Among 7 of 19 inferior infarction patients with right ventricular by scintigraphy, right ventricular EF was reduced (0.39 +/- 0.05; P less than 0.001 vs normals; P less than 0.01 vs inferior infarction patients without right ventricular involvement). In the latter group right ventricular EF averaged 0.51 +/- 0.10 (NS vs normals). We conclude 1) a single injection of 99mTc (Sn) pyrophosphate can identify right and left ventricular dysfunction and infarct location in acute myocardial infarction, 2) right ventricular EF is well-preserved except when inferior infarction involves the right ventricle.     

Postinfarction ventricular septal rupture: the importance of location of infarction and right ventricular function in determining survival

Over a 5.5 year period, 1264 consecutive patients with acute myocardial infarction as confirmed by enzyme levels were prospectively identified. Of these, 25 (2%) suffered ventricular septal rupture (pulmonary/systemic flow range 1.5 to 6) 7 +/- 7 days after onset of myocardial infarction. Death occurred in 14 patients (56%) and was more common after inferior than anterior myocardial infarction (11 of 15 [73%] vs three of 10 [30%], p less than .05). Among 133 variables analyzed, survivors and nonsurvivors were similar with respect to all premorbid clinical characteristics, infarct size as assessed by peak creatine kinase values, shunt size, two-dimensional echocardiographic and hemodynamic indexes of left ventricular function, and extent of coronary disease. Compared with survivors, the nonsurvivors had greater impairment of right ventricular function as determined by a higher two-dimensional echocardiographically derived right ventricular wall motion index (RVWMI) (0.55 +/- 0.87 vs 1.70 +/- 0.45, p less than .001), greater elevation of right ventricular end-diastolic pressure (11 +/- 6 vs 17 +/- 6, p less than .02), and greater mean right atrial pressure (10 +/- 6 vs 16 +/- 3, p less than .01). Of interest, two of the three patients who presented with anterior myocardial infarction and who died had inferiorly extended infarcts and all had abnormal RVWMIs (greater than or equal to 1.0). As expected, cardiogenic shock shortly after onset of ventricular septal rupture was associated with a 91% mortality, but was more common after inferior than anterior myocardial infarction (60% vs 20%, p less than .05). The mean effective cardiac index was also higher in survivors than nonsurvivors (2.1 +/- 0.5 vs 1.2 +/- 0.5, p less than .001). Finally, multivariate analysis indicated that all nonsurvivors could be identified based on: an effective cardiac index of 1.75 liters/min/m2 or less, the presence of extensive right ventricular and septal dysfunction on the two-dimensional echocardiogram, a mean right atrial pressure of 12 mm Hg or more, and early onset of ventricular septal rupture. Thus, our data demonstrate that: mortality is higher when ventricular septal rupture complicates inferior than when it complicates anterior myocardial infarction, survivors can be distinguished from nonsurvivors and the prediction of outcome is highly accurate, and combined right ventricular and septal dysfunction has a substantial impact on prognosis.     

Serial assessment of right ventricular function in the acute and convalescent stages after successful reperfusion: relationship to infarct-related coronary artery

OBJECTIVES: To elucidate the relationship between the infarct-related coronary artery and the right ventricular function before and after successful recanalization. METHODS: Hemodynamics and right ventricular function were measured using a REF-1 thermodilution catheter before and shortly after recanalization and during the convalescent stage in 35 patients, 17 with anteroseptal and 18 with inferior acute myocardial infarction. RESULTS: Pulmonary arterial pressure significantly decreased in both anteroseptal and inferior myocardial infarction patients after recanalization. Right ventricular volume index in patients with anteroseptal myocardial infarction increased after recanalization, but again decreased during convalescence. The right ventricle became enlarged in patients with inferior myocardial infarction to maintain the right ventricular stroke volume constant. Right ventricular ejection fraction (RVEF) did not significantly change in patients with inferior myocardial infarction during convalescence (38 +/- 13%, 38 +/- 13%, 46 +/- 9%), whereas RVEF in patients with anteroseptal myocardial infarction temporarily decreased after recanalization, and then increased during convalescence (37 +/- 10%, 31 +/- 12%, 41 +/- 7%). Patients with inferior myocardial infarction were divided into two groups, patients with increased RVEF (n = 6) and decreased RVEF (n = 12) shortly after recanalization. Patients with increased RVEF showed significantly improved RVEF during convalescence (49 +/- 7% vs 37 +/- 6%, p < 0.05). The increase in RVEF shortly after recanalization in patients with inferior myocardial infarction was an independent factor for predicting RVEF during convalescence. CONCLUSIONS: Patients with anteroseptal myocardial infarction showed a different pattern of change in the right ventricular function during the acute and convalescent stages. An early change in RVEF in patients with inferior myocardial infarction can predict RVEF in the convalescent stage.     

Development of collateral circulation after acute myocardial infarction: its role in preserving left ventricular function

The present study evaluated the effects of coronary collateral circulation developing after acute myocardial infarction on global and regional left ventricular function during the chronic stage. The study group consisted of 16 patients with initial myocardial infarction having total occlusion of the proximal left anterior descending coronary artery. To eliminate the effects of collateral circulation existing at the onset of infarction, patients with pre-infarction angina were excluded from this study. The patients were categorized in two groups depending on the extent of their collateral circulation (collateral index: CI 0-3): group A--patients with significant collateral circulation (CI = 2 or 3) to the infarct-related coronary artery; group B--patients without significant collateral circulation (CI = 0 or 1). Their heart rate, left ventricular peak systolic and end-diastolic pressures and cardiac index were similar in the two groups. The left ventricular end-systolic volume index in the group B was significantly greater than that in the group A (60 +/- 21 ml/m2 vs 34 +/- 9 ml/m2, p less than 0.05). Left ventricular ejection fraction in the group A was significantly greater than that of the group B (55 +/- 9% vs 39 +/- 15%, p less than 0.05), and a significant difference was observed in the percentage of segment shortening in the infarct area between the groups A and B (10.8 +/- 9.2% vs -0.2 +/- 5.4%, p less than 0.01). It was concluded that coronary collateral circulation which develops after acute myocardial infarction exerts beneficial effects on global and regional left ventricular function during the chronic stage.     

New parameters in identification of right ventricular myocardial infarction and proximal right coronary artery lesion

OBJECTIVE: The diagnosis of right ventricular myocardial infarction (RVMI) accompanied by acute inferior myocardial infarction (MI) is still a problem that we encounter. This study was designed to find out the usefulness both of peak myocardial systolic velocity (Sm) and of the myocardial performance index (MPI) of the right ventricle measured by pulsed-wave tissue Doppler imaging (TDI) in assessing right ventricular function. METHODS: Sixty patients who experienced a first acute inferior MI (mean [+/- SD] age, 57 +/- 9 years) were prospectively assessed. An ST-segment elevation of >or= 0.1 mV in V(4)-V(6)R lead derivations was defined as an RVMI. From the echocardiographic apical four-chamber view, the Sm, the peak early diastolic velocity, peak late diastolic velocity, the ejection time, the isovolumetric relaxation time, and the contraction time of the right ventricle were recorded at the level of the tricuspid annulus by using TDI. Then, the MPI was calculated. The patients were classified into the following three groups, according to the localization of the infarct-related artery (IRA) detected using coronary angiography: group I, proximal right coronary artery; group II, distal right coronary artery; and group III, circumflex coronary artery. RESULTS: RVMIs were detected in sixteen patients, and the IRA in 27 patients was the proximal right coronary artery. The right ventricular Sm was observed to be significantly low in patients with RVMIs and those in group I compared to those without RVMIs and those in groups II and III (10.9 +/- 1.3 vs 14.3 +/- 3.2 cm/s, respectively [p < 0.001]; 11.5 +/- 2.5 vs 15.1 +/- 3 cm/s, respectively; and 14.9 +/- 2.6 cm/s, respectively [p < 0.001]). In the diagnosis of RVMI, the values for sensitivity, specificity, negative predictive value, and positive predictive value of Sm < 12 cm/s were 81%, 82%, 92%, and 62% respectively, and in the diagnosis of the proximal right coronary artery as the IRA, those values were 63%, 88%, 74%, and 81%, respectively. The MPI was high in the same patient groups (0.83 +/- 0.12 vs 0.57 +/- 0.11 in those patients without RVMI, respectively, [p < 0.001]; 0.74 +/- 0.13 vs 0.56 +/- 0.15 in group II and 0.54 +/- 0.07 in group III, respectively [p < 0.001]). The sensitivity, specificity, negative predictive value, and positive predictive value of an MPI of > 0.70 in the diagnosis of RVMI were calculated as 94%, 80%, 97%, and 63%, respectively, and in the diagnosis of the proximal right coronary artery as the IRA, those values were 78%, 91%, 83%, and 88% respectively. CONCLUSIONS: An Sm <12 cm/s and an MPI > 0.70 obtained by TDI may define RVMI concomitant with acute inferior MI, and the IRA.     

Right ventricular strain and strain rate properties in patients with right ventricular myocardial infarction

BACKGROUND: This study was planned to assess strain and strain rate properties of right ventricle in patients with RV myocardial infarction. MATERIAL AND METHOD: Thirty patients with acute inferior myocardial infarction were included in this study. The presence of right ventricular infarction in association with an inferior myocardial infarction was defined by an ST-segment elevation 0.1 mV in lead V4 R. According to this definition, 15 patients had electrocardiographic signs of inferior myocardial infarction without right ventricular infarction (group I), and 15 patients had electrocardiographic signs of inferior myocardial infarction with right ventricular infarction (group II). Echocardiography was performed using a Vivid 5 System (GE Ultrasound; Horten, Norway) and a 2.5-MHz transducer. 2-dimensional color doppler myocardial imaging (CDMI) data for longitudinal function were recorded from the RV free wall using standard apical view. Offline analysis of the myocardial color Doppler data for regional velocity (V), strain rate (Sr), and strain (S) curves was performed using a special software program (EchoPac 6.4 Vingmed, Horten, Norway). They were assessed in basal, middle and apical segments of the RV. The differences between different groups were assessed with the Mann-Whitney U-test. A value of P < 0.05 was considered statistically significant. RESULTS: Systolic tissue velocity, strain, strain rate of basal (4.8 +/- 0.8 cm/s vs 6.5 +/- 1.2 cm/s, -12 +/- 3% vs -24 +/- 5%, 1.28 +/- 0.3/s vs -1.9 +/- 0.4/s; P < 0.001, <0.001, <0.001, respectively) and mid (4.2 +/- 0.5 cm/s vs 5.4 +/- 0.5 cm/s, -16 +/-3% vs -26 +/- 4%, -1.2 +/- 0.3/s vs -2.1 +/- 0.3/s; P < 0.001, <0.001, <0.001, respectively) segments of right ventricle were significantly lower in patients with RV infarction than in patients without RV infarction. There were no differences between groups for apical strain, strain rate, and systolic tissue velocity. CONCLUSION: This study demonstrates that right ventricular strain and strain rate were lower in patients with left ventricular inferior wall myocardial infarction with, compared to without, right ventricular infarction.     

Role of right ventricular asynergy and tricuspid regurgitation in hemodynamic alterations during acute inferior myocardial infarction

To elucidate the role of right ventricular asynergy and tricuspid regurgitation (TR) in hemodynamic alterations occurring during right ventricular infarction, left and right ventriculography with pressure measurements were performed in 22 patients with acute inferior myocardial infarction. Twelve patients with a proximal right coronary artery (RCA) occlusion (Group I) had elevated right atrial pressure (16 +/- 4 vs 8 +/- 5 mmHg, p less than 0.01), low cardiac output (2.5 +/- 0.7 vs 3.5 +/- 0.6 l/min/m2, p less than 0.05) and a greater degree of TR, compared with 10 patients with a distal RCA occlusion (Group II). Inferoposterior wall asynergy of the right and left ventricles was similar in Groups I and II. In Group I, there was an additional asynergy of the anterolateral free wall of the right ventricle. Cardiac output in those patients was not related to the left ventricular ejection fraction (EF) but to the right ventricular EF. A greater degree of TR was found in association with a lower right ventricular EF. The decrease in cardiac output was closely related to the extent of TR. These results indicate that right ventricular asynergy and TR due to proximal RCA occlusion may play important roles as causes of hemodynamic alterations seen during the acute phase of inferior myocardial infarction.     

Right ventricular hypertrophy is an important determinant of right ventricular infarction complicating acute inferior left ventricular infarction

To explore the role of right ventricular hypertrophy and chronic obstructive pulmonary disease in the pathogenesis of right ventricular infarction, 27 consecutive patients with a first inferior left ventricular infarction were prospectively studied. Right ventricular infarction was diagnosed using established hemodynamic criteria. Right ventricular hypertrophy was defined as right ventricular free wall thickness greater than or equal to 5 mm. Patients were classified into two groups: Group I patients with right ventricular infarction (n = 15), and Group II patients without right ventricular infarction (n = 12). The ratio of forced expiratory volume over forced vital capacity (FEV1/FVC) and forced expiratory flow between 25 and 75% expired volume (FEF) as a percent of predicted values were significantly reduced in Group I versus Group II (90 +/- 5 versus 105 +/- 6% and 63 +/- 13 versus 103 +/- 15%, respectively; p less than 0.05). This was associated with increased right ventricular wall thickness (Group I 5.5 +/- 0.3 mm versus Group II 3.9 +/- 0.2 mm, p less than 0.001). Multiple logistic regression analysis demonstrated that right ventricular wall thickness was the strongest predictor of right ventricular infarction (p less than 0.0005). No significant difference was found in the site of right coronary occlusion, collateral blood supply or extent of coronary artery disease between the two groups. These findings suggest that right ventricular hypertrophy predisposes patients with acute inferior myocardial infarction to right ventricular infarction independent of the site or extent of coronary artery disease.     

Comparison of the influence of acute transmural and nontransmural myocardial infarction on ventricular function

In order to assess the relative impact on left and right ventricular function of nontransmural and transmural acute myocardial infarction (AMI), we performed radionuclide ventriculography in 86 patients (54 men and 32 women) within 16 hours after a first infarct. Nontransmural infarction was present in 19 patients (11 anterior and 8 inferior). Transmural infarction was found in 67 patients (30 anterior and 37 inferior). Left ventricular ejection fractions were higher (0.57 +/- .014 vs 0.46 +/- 0.14, p less than 0.005) and left ventricular end-systolic volume lower (29 +/- 11 vs 42 +/- 20 ml/m2, p = 0.013) in patients with nontransmural infarction compared to those with transmural infarction. Right ventricular ejection fraction also may have been different in the two groups (0.63 +/- 0.15 vs 0.55 +/- 0.13, p = 0.057). In patients with inferior infarction, left and right ventricular ejection fractions were similar in patients with nontransmural and transmural infarction (0.60 +/- 0.09 vs 0.55 +/- 0.10, p = 0.119 and 0.58 +/- 0.14 vs 0.51 +/- 12, p = 0.226). On the other hand, patients with anterior transmural infarction had lower left ventricular ejection fractions (0.36 +/- 0.12 vs 0.54 +/- 0.17, p = 0.003) but similar right ventricular ejection fractions (0.60 +/- 0.13 vs 0.66 +/- 0.14, p = 0.14) compared to those with nontransmural anterior infarction. In 29 additional patients with a history of previous infarction, no differences in any of the parameters studied were found between those with transmural and those with nontransmural infarcts.(ABSTRACT TRUNCATED AT 250 WORDS)     

Early reperfusion therapy improves left ventricular function after acute inferior myocardial infarction associated with right coronary artery disease

Quantitative global and regional ventriculographic analysis was performed acutely and 1 week later in 46 patients undergoing reperfusion procedures within 6 hours of acute inferior myocardial infarction due to right coronary artery disease. While serial improvement in global left ventricular ejection fraction was not demonstrated for the group, infarct zone regional wall motion did improve (-2.7 +/- 0.9 vs -2.3 +/- 1.4 SD/chord, p less than 0.007). Serial improvement in global ejection fraction was demonstrated in the subgroup of patients treated within 2 hours of symptom onset (55 +/- 10 vs 62 +/- 10%; n = 5; p less than 0.03). Infarct zone regional wall motion improved serially only in the subgroup of patients treated within 3 hours of symptom onset (-2.4 +/- 1.1 vs -1.3 +/- 1.7 SD/chord; n = 11; p less than 0.007). Patients with initially patent arteries had a higher ejection fraction on follow-up catheterization than did those with initially occluded vessels (61 +/- 11 vs 55 +/- 7%; p less than 0.02), and patients with patent arteries at follow-up had a higher ejection fraction than did those whose arteries were occluded (60 +/- 9 vs 48 +/- 4%; p less than 0.0001). We conclude that significant improvement in global and regional left ventricular function in patients with inferior myocardial infarction is possible when reperfusion therapy is begun early or when arterial patency is achieved.     

The effect of diabetes on heart rate and other determinants of myocardial oxygen demand in acute coronary syndromes.

AIMS: To compare major determinants of myocardial oxygen demand (heart rate, blood pressure and rate pressure product) in patients with and without diabetes admitted with acute coronary syndromes. METHODS: A cross-sectional study of the relation between diabetes and haemodynamic indices of myocardial oxygen demand in 2542 patients with acute coronary syndromes, of whom 1041 (41.0%) had acute myocardial infarction and 1501 (59.0%) unstable angina. RESULTS: Of the 2542 patients, 701 (27.6%) had diabetes. Major haemodynamic determinants of myocardial oxygen demand were higher in patients with than without diabetes: heart rate 80.0 +/- 20.4 vs. 75.2 +/- 19.2 beats/minute (P < 0.0001); systolic blood pressure 147.3 +/- 30.3 vs. 143.2 +/- 28.5 mmHg (P = 0.002); rate-pressure product 11533 +/- 4198 vs. 10541 +/- 3689 beats/minute x mmHg (P < 0.0001). Multiple regression analysis confirmed diabetes as a significant determinant of presenting heart rate [multiplicative coefficient (MC) 1.05; 95% confidence interval (CI) 1.03-1.07; P < 0.0001], rate pressure product (MC 1.09; CI 1.05-1.12; P < 0.0001) and systolic blood pressure, which was estimated to be 3.9 mmHg higher than in patients without diabetes (P=0.003). These effects of diabetes were independent of a range of baseline variables including acute left ventricular failure and mode of presentation (unstable angina or myocardial infarction). CONCLUSIONS: In acute coronary syndromes, heart rate and other determinants of myocardial oxygen demand are higher in patients with than without diabetes, providing a potential contributory mechanism of exaggerated regional ischaemia in this high-risk group.     

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.     

Chronic effects of myocardial infarction on right ventricular function: a noninvasive assessment

To assess the chronic effects of myocardial infarction on right ventricular function, 48 subjects were studied utilizing radionuclide angiography and two-dimensional echocardiography. Ten were normal subjects (group I), 11 had previous inferior wall myocardial infarction (group II), 10 had previous anteroseptal infarction (group III), 11 had combined anteroseptal and inferior infarction (group IV) and 6 had extensive anterolateral infarction (group V). The mean (+/- standard deviation) left ventricular ejection fraction was 0.66 +/- 0.03 in group I, 0.58 +/- 0.02 in group II, 0.52 +/- 0.02 in group III, 0.33 +/- 0.03 in group IV and 0.33 +/- 0.01 in group V. No systematic correlation between left and right ventricular ejection fraction was observed among the groups. The mean right ventricular ejection fraction was significantly reduced in the presence of inferior myocardial infarction (0.30 +/- 0.03 in group II and 0.29 +/- 0.03 in group IV compared with 0.43 +/- 0.02 in group I [p less than 0.001]). The group II and IV patients also had increased (p less than 0.001) right ventricular end-diastolic area and decreased (p less than 0.001) right ventricular free wall motion by two-dimensional echocardiography. In the presence of anteroseptal infarction (group III), right ventricular free wall motion was increased (p less than 0.05) compared with normal subjects (group I). Thus, the effects of prior myocardial infarction on right ventricular function depend more on the location of infarction than on the extent of left ventricular dysfunction. Inferior infarction was commonly associated with reduced right ventricular ejection fraction and increased right ventricular end-diastolic area. The right ventricular free wall excursion was increased in the presence of anteroseptal infarction, suggested loss of contribution of interventricular septal contraction to right ventricular ejection.