Mark R. Starling

Comparative accuracy of apical biplane cross-sectional echocardiography and gated equilibrium radionuclide angiography for estimating left ventricular size and performance.

To compare measurements of left ventricular size and performance obtained by apical biplane cross-sectional echocardiography (CSE) and gated equilibrium radionuclide angiography (RNA), we studied 70 patients, all of whom had single-plane and 30 of whom had biplane left ventricular cineangiography. Wideangle, phased-array CSE images were obtained from two orthogonal apical views and left ventricular volumes were calculated using a microprocessor-controlled, video light-pen system programmed for a Simpsons rule algorithm. The average CSE end-diastolic volume (EDV) for all 70 patients of 158 ± 56 ml (± SD) was less than the single-plane angiographic value of 176 ± 68 ml (p < 0.001, r = 0.80). The average CSE end-systolic volume (ESV) of 78 ± 57 ml was not different from the angiographic value of 84 ± 70 ml (r = 0.88). The average CSE and single-plane angiographic ejection fraction (EF) values of 55 ± 16% and 57 ± 19% were not different (r = 0.90). In the 30 patients who underwent biplane angiography, the average CSE EDV of 166 ± 62 ml was less than the biplane angiographic EDV of 217 ± 87 ml (p < 0.001, r = 0.81), and the average CSE ESV of 89 ± 69 ml was also less than the angiographic value of 114 ± 89 ml (p < 0.001, r = 0.92). The average CSE LV EF of 52 ± 19% was not different from the biplane angiographic value of 52 ± 17% (r = 0.87). In the 25 patients who underwent CSE, RNA and biplane angiography, the average LVEF values were 51 ± 20%, 46 ± 18% and 50 ± 17%, respectively, and the CSE and RNA values correlated with the biplane angiographic value (r = 0.90 and 0.93, respectively). Therefore, apical biplane CSE estimates of left ventricular volume correlate linearly with single-plane and biplane cineangiographic determinations, and this CSE technique compares favorably with gated equilibrium RNA for assessing left ventricular performance.

Exercise testing early after myocardial infarction: Predictive value for subsequent unstable angina and death

Recently, modified treadmill exercise testing before hospital discharge has been reported to be safe in patients after uncomplicated myocardial infarction. Accordingly, the frequency of treadmill exercise-induced abnormalities and their prognostic value were evaluated in 130 patients with uncomplicated myocardial infarction. Seventy-eight patients (60 percent) had one or more treadmill exercise-induced abnormalities; 42 had S-T segment depression, 35 had angina and 17 had an inadequate blood pressure response. During the mean follow-up period of 11 months, 27 patients experienced unstable angina, 12 had a recurrent myocardial infarction and 10 died of cardiac causes. Compared with patients with no exercise-induced abnormality, patients with S-T segment depression, angina pectoris or an inadequate blood pressure response had a significantly greater (p < 0.001) incidence of all cardiac events during the follow-up period. Furthermore, unstable angina pectoris was significantly more frequent (p < 0.005) in patients with S-T segment depression or angina pectoris. Finally, when the patients with ischemic treadmill abnormalities were combined with the patients exhibiting an inadequate blood pressure response, they had a statistically greater (p < 0.005) incidence of cardiac death than that of patients with no treadmill abnormalities. Therefore, these three abnormalities during modified treadmill exercise testing before hospital discharge identify patients with uncomplicated myocardial infarction who are at risk for a future cardiac event.

Right ventricular infarction: Identification by hemodynamic measurements before and after volume loading and correlation with noninvasive techniques

To evaluate the potential occurrence of right ventricular infarction, 53 patients with acute inferior transmural myocardial infarction were studied within 36 hours of symptoms by right heart catheterization, equilibrium radionuclide angiography and two-dimensional echocardiography. Technetium-99m pyrophosphate myocardial scintigraphy was performed 3 days after the onset of symptoms. The hemodynamic standard for right ventricular infarction was defined as both a right atrial pressure of 10 mm Hg or more and a right atrial/pulmonary artery wedge pressure ratio of 0.8 or more. Eight (15%) of the 53 patients had hemodynamic measurements at rest characteristic of right ventricular infarction, and 6 (11%) additional patients met these criteria after volume loading (p less than 0.05). Nineteen (37%) of the 51 patients who had radionuclide angiography had right ventricular dysfunction manifested by both a reduced right ventricular ejection fraction (less than 40%) and right ventricular regional wall motion abnormalities (akinesia or dyskinesia). An abnormal radionuclide angiogram was observed in 12 of 13 patients with hemodynamic measurements indicating right ventricular infarction. In 12 patients with an abnormal radionuclide angiographic study, right ventricular ejection fraction improved 6 to 12 weeks after infarction (27 +/- 7 to 36 +/- 9%, p less than 0.01). Twenty-two (49%) of the 45 patients with adequate two-dimensional echocardiograms had a right ventricular regional wall motion abnormality. An abnormal two-dimensional echocardiogram was seen in 9 of 11 patients with hemodynamic measurements characteristic of right ventricular infarction. Technetium-99m pyrophosphate scintigraphy was positive for right ventricular infarction in 3 of 12 patients who had hemodynamic measurements indicating right ventricular infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Impaired left ventricular contractile function in patients with long-term mitral regurgitation and normal ejection fraction☆☆☆

OBJECTIVES We tested the hypotheses that left ventricular chamber elastance would detect impaired contractile function in patients with long-term mitral regurgitation and a normal ejection fraction and that these patients would have unique temporal left ventricular size and ejection fraction responses to mitral valve surgery. BACKGROUND Although it has been suggested that left ventricular contractile function may begin deteriorating in patients with long-term mitral regurgitation whereas ejection fraction remains normal, no data exist in humans. METHODS We studied 11 control patients and 28 patients with long-term mitral regurgitation using micromanometer-measured pressures, biplane contrast cineventriculography and radionuclide angiography under control conditions and with alterations in load during right atrial pacing to calculate left ventricular chamber elastance and myocardial stiffness. RESULTS The patients with mitral regurgitation were classified into subgroups: Group I, normal contractile function; Group II, impaired contractile function (reduced Emax) but normal ejection fraction, and Group III, impaired contractile function (reduced Emax) with reduced systolic myocardial stiffness. Twenty-two of the patients with mitral regurgitation underwent mitral valve surgery. In Group I, comparable decreases in left ventricular volume indexes (p < 0.01 and p = 0.05, respectively) were associated with no change in ejection fraction at 3 months and 1 year. In contrast, in Group II, reductions in volume indexes (p < 0.0001 and p < 0.001) were associated with a short-term decrease in ejection fraction (p < 0.001) that recovered at 1 year (p < 0.01 vs. short-term). Finally, in Group III, variable responses in volume indexes were associated with a consistent decrease in ejection fraction at 3 months and 1 year. CONCLUSIONS An analysis of left ventricular chamber elastance provides data to support the concepts that 1) contractile function is impaired in some patients with long-term mitral regurgitation and a normal ejection fraction, 2) impaired contractile function may not be irreversible in all of these patients, and 3) an earlier consideration of mitral valve surgery may be warranted to preserve contractile function in these patients.

Comparative effects of volume loading, dobutamine, and nitroprusside in patients with predominant right ventricular infarction.

To assess the value of volume loading and to determine the relative efficacy of dobutamine compared with nitroprusside therapy in acute right ventricular infarction (RVMI), 13 patients with clinical, hemodynamic, and radionuclide angiographic evidence of RVMI were evaluated. In 10 patients who had an initial pulmonary arterial wedge pressure less than 18 mm Hg, volume loading did not improve cardiac index (1.9 +/- 0.5 [SD] to 2.1 +/- 0.4 liters/min/m2), despite significant increases in mean right atrial pressure (11 +/- 2 to 15 +/- 2 mm Hg, p less than .001) and pulmonary arterial wedge pressure (10 +/- 4 to 15 +/- 2 mm Hg, p less than .001). Nine patients received dobutamine or nitroprusside in random order, while hemodynamic measurements and radionuclide angiograms were obtained simultaneously. Compared with nitroprusside, dobutamine produced a statistically significant increase in cardiac index (2.0 +/- 0.4 to 2.7 +/- 0.5 vs 2.1 +/- 0.4 to 2.3 +/- 0.5 liters/min/m2, p less than .001), stroke volume index (29 +/- 6 to 36 +/- 8 vs 29 +/- 6 to 30 +/- 6 ml/m2, p = .02), and right ventricular ejection fraction (30 +/- 8% to 42 +/- 7% vs 34 +/- 8% to 37 +/- 4%, p less than .01) by two-way analysis of variance. We conclude that volume loading does not improve cardiac index in patients with acute RVMI despite a rise in cardiac filling pressures and that infusion of dobutamine, after appropriate volume loading, produces a significant improvement in cardiac index and right ventricular ejection fraction over those after infusion of nitroprusside.

Effects of Valve Surgery on Left Ventricular Contractile Function in Patients With Long-term Mitral Regurgitation

BACKGROUND Patients with long-term mitral regurgitation were studied both before and 1 year after successful valve surgery to test the hypothesis that impaired left ventricular contractile function improves after surgery for long-term mitral regurgitation in humans. METHODS AND RESULTS Fifteen patients with long-term mitral regurgitation were studied. Micromanometer left ventricular pressures and radionuclide angiograms for left ventricular volumes were acquired over a range of loading conditions both before and 1 year after successful valve surgery for long-term mitral regurgitation. To assess both left ventriculoarterial coupling to evaluate the interaction of the left ventricle with the arterial system with the use of the left ventricular contractile index, Ees, and effective arterial elastance, Ea. Left ventricular pump efficiency was expressed as the ratio of forward left ventricular stroke work to the corresponding pressure-volume area. All patients had successful mitral valve surgery as manifest by no or only trivial residual mitral regurgitation on physical examination and Doppler echocardiography. The average radionuclide regurgitant index of 1.28 +/- 0.56 was also less than the preoperative value of 2.70 +/- 0.80 (P < .0001). The mean left ventricular end-diastolic volume index decreased from 137 +/- 37 to 90 +/- 31 mL/m2 (P < .001), and the average left ventricular end-systolic volume index also decreased (59 +/- 29 to 45 +/- 27 mL/m2, P < .01), although individual variation was observed. The average left ventricular ejection fraction fell from 0.58 +/- 0.12 to 0.53 +/- 0.16, which was not significant. In contrast, Ees increased from a mean value of 0.95 +/- 0.66 mm Hg/mL during the preoperative study to 2.62 +/- 2.16 mm Hg/mL at the 1-year postsurgical study (P < .01). This improvement in left ventricular contractility was observed in patients with long-term mitral regurgitation, who before surgery had preserved left ventricular ejection fraction (P < .001), less left ventricular dilation at end diastole (P < .01) and end systole (P < .001), and less impaired left ventricular contractility. Because effective arterial elastance was unchanged, left ventriculoarterial coupling also improved from an average of 0.47 +/- 0.39 to 1.81 +/- 1.63 (P < .01). Consequently, left ventricular pump efficiency improved from a mean preoperative value of 0.23 +/- 0.10 to 0.55 +/- 0.22 at the 1-year postsurgical study (P < .0001). CONCLUSIONS The results indicate that left ventricular contractile impairment is reversible in many patients with long-term mitral regurgitation. In fact, these data indicate that mitral valve surgery can be recommended to preserve left ventricular contractility in patients with long-term mitral regurgitation, particularly in those patients who before surgery have normal left ventricular ejection fractions and less left ventricular dilation and contractile impairment.

Left ventricular-arterial coupling relations in the normal human heart

This investigation was undertaken to assess left ventricular-arterial coupling relations in the normal human heart under varying loading conditions and inotropic states and thereby to establish whether the working point of the normal human heart is at optimal output or mechanical efficiency under basal hemodynamic conditions. In 22 patients with an atypical chest pain syndrome who had normal coronary arteriograms, left ventricular (LV) pressures, volumes, ejection fractions, and masses at cardiac catheterization, we acquired radionuclide angiograms in duplicate simultaneously with micromanometer LV pressures. These values were derived under control conditions and during methoxamine and nitroprusside infusions with heart rate held constant by right atrial pacing. Seven other patients underwent the same protocol but, in addition, we acquired these parameters during a steady-state, intravenous infusion of dobutamine (5 micrograms/kg/min). The interaction of LV chamber elastance (Ees) and effective arterial elastance (Ea) revealed that the normal human heart was operating at an Ees/Ea ratio of 1.62, a stroke work of 76 +/- 31 gm-m, and a mechanical efficiency (stroke work to pressure-volume area ratio [SW/PVA]) of 0.65 +/- 0.10. With an increase in LV load, the Ees/Ea ratio approached 1 (p < 0.01), LV stroke work increased (p < 0.01), and mechanical efficiency declined (p < 0.01). In contrast, during vasodilation, the Ees/Ea ratio increased to slightly above 2.0 (p < 0.01), LV stroke work decreased (p < 0.001), and mechanical efficiency improved (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Load independence of the rate of isovolumic relaxation in man.

This investigation was designed to determine whether the rate of isovolumic left ventricular pressure decline is affected by load in man. Fourteen patients were instrumented with micromanometer left ventricular and right atrial pacing catheters to maintain a constant heart rate during control conditions and infusion of methoxamine or nitroprusside. The isovolumic relaxation period was defined as the time from peak (-)dP/dt to 5 mm Hg above left ventricular end-diastolic pressure of the following beat. The rate of isovolumic relaxation was calculated as time constants (Tau) from the linear regression of natural log pressure vs time (Tln) and instantaneous (-)dP/dt vs pressure (TD), which includes a variable asymptote (PB). The mean heart rates and average (+)dP/dt values normalized at 40 mm Hg development pressure (DP40) did not differ significantly, despite 33% and 43% increases in left ventricular peak and end-diastolic pressures during the infusion of methoxamine (p less than .001 and p less than .01, respectively) and 24% and 29% decreases during the infusion of nitroprusside (p less than .001 and p less than .01, respectively). The average Tln and TD values were not significantly affected by these alterations in load. In two patients, an inverse linear relationship was demonstrated between decreases in Tau and increases in contractile state produced by an infusion of dobutamine, as shown by correlation of Tln and TD with (+)dP/dt/DP40 (r = -.88 and -.83, respectively). We conclude that the time constants of left ventricular isovolumic relaxation are unaffected by modest alterations in loading conditions in man when heart rate is maintained constant.(ABSTRACT TRUNCATED AT 250 WORDS)

Physical Examination for Exclusion of Hemodynamically Important Right Ventricular Infarction

Fifty-three consecutive patients with inferior myocardial infarction were evaluated prospectively, by physical examination and right heart catheterization within 36 hours of the onset of symptoms, to determine whether physical findings can separate such patients into those with and without associated right ventricular infarction. Hemodynamic findings consistent with right ventricular infarction were defined as right atrial pressure of 10 mm Hg or greater and a right atrial: pulmonary artery wedge pressure ratio of 0.80 or greater. Eight patients (Group 1) had hemodynamic evidence of right ventricular infarction, whereas 45 patients (Group 2) did not meet these criteria. Group 1, compared with Group 2, had a lower cardiac index (1.8 +/- 0.3 versus 2.6 +/- 0.6 L/min X m2, p less than 0.001), and a lower right ventricular stroke work index (4.1 +/- 3.6 versus 7.3 +/- 3.2 g X m/m2, p less than 0.05). An elevated jugular venous pressure of 8 cm H2O or more was seen in 7 of 8 Group 1 and 14 of 45 Group 2 patients (p less than 0.01). In addition, a Kussmauls sign, substantiated by hemodynamic findings, was seen in all 8 Group 1 and in no Group 2 patients (p less than 0.001). The absence of both an elevated jugular venous pressure and a Kussmauls sign in patients with inferior myocardial infarction makes the presence of a hemodynamically significant right ventricular infarction highly unlikely.

A new two-dimensional echocardiographic technique for evaluating right ventricular size and performance in patients with obstructive lung disease.

To compare two-dimensional (2-D) echocardiographic estimates of right ventricular size and performance to similar determinations from equilibrium radionuclide angiography (RNA) before and after isosorbide dinitrate, we evaluated 19 patients with severe chronic obstructive pulmonary disease. The enddiastolic and end-systolic volumes estimated from subcostal 2-D echocardiographic views of the right ventricle correlated with the RNA end-diastolic and end-systolic counts (r = 0.76 and 0.82, respectively). The 2-D echocardiographic and RNA right ventricular ejection fraction (EF) estimates also correlated (r = 0.80), and the average right ventricular EF measures of 42 ± 11% and 40 ± 12%, respectively, did not differ significantly. Nitrate administration produced a significant increase in heart rate (99 ± 11 to 108 ± 14 beats/mm, p < 0.001) and a decrease in systolic arterial pressure (139 ± 23 to 120 ± 22 mm Hg, p < 0.001). Nitrates also significantly decreased the average 2-D echocardiographic end-diastolic and endsystolic volumes (22 ± 16% and 18 ± 12%, p < 0.001), as well as RNA end-diastolic and end-systolic counts (33 ± 17% and 32 ± 22%, p < 0.001), but did not significantly decrease the average right ventricular EF values (4 ± 12% and 4 ± 24%, respectively). Nevertheless, after isosorbide dinitrate, the 2- echocardiographic right ventricular end-diastolic and end-systolic volume estimates continued to correlate with the corresponding RNA count measures (r = 0.76 and 0.79, respectively), as did the 2-D echocardiographic and RNA right ventricular EF values (r = 0.75). We conclude that 2-D echocardiographic evaluation of right ventricular size and performance is feasible in selected patients with chronic obstructive pulmonary disease, and that 2-D echocardiographic measures of right ventricular size and performance compare favorably with similar determinations by RNA at rest and after nitrate administration.