Serial M-mode echocardiographic mapping in myocardial infarction: a quantitative evaluation of left ventricular wall motion abnormalities

Evaluation of effects of nitroglycerin therapy by echocardiography

Echocardiography (Echo) is a convenient method in diagnosing and in quantification of cardiac abnormalities, although dependent on registration quality. M-mode and two-dimensional Echo give adequate information regarding heart dimensions and cavity volume but only indirect information of pressures. M-mode Echo gives an ideal opportunity to study left ventricular wall motion as an expression of systolic and diastolic function. Both inter and intra patient comparisons will be possible to perform. Improved wall function after intake of nitroglycerin and other nitrate preparations, has been reported in Echo studies both in resting state and in induced acute myocardial ischemia during exercise in man or in acute coronary occlusion in dogs.

Long-term calcium antagonist treatment of human hypertension with mibefradil or amlodipine increases sympathetic nerve activity

OBJECTIVES

Calcium antagonists are vasodilating drugs, which may cause reflex activation of the sympathetic nervous system with potentially untoward effects. We studied the effects of long-term treatment with amlodipine, a long-acting dihydropyridine-type calcium antagonist, and mibefradil, a phenylalkylamine-type calcium antagonist, on sympathetic nerve activity.

METHODS

Fourteen patients with primary hypertension participated in a double-blind, cross-over study comparing the effects of 6 weeks of treatment with mibefradil 100 mg daily and amlodipine 10 mg daily. Heart rate, direct arterial blood pressure and cardiac output by echocardiography were registered. Global sympathetic activity was estimated using a [3H]noradrenaline isotope dilution method with arterial and venous sampling; cardiac sympathetic activity was assessed indirectly by heart rate variability and tissue velocity echocardiography.

RESULTS

Both drugs lowered mean arterial pressure; the decrease was more pronounced with mibefradil (from 118 +/- 3 to 99 +/- 2 mmHg, compared to 118 +/- 3 to 104 +/- 2 mmHg for amlodipine, P < 0.01 between drugs). Mibefradil decreased heart rate (66 +/- 2 to 57 +/- 2 bpm), whereas amlodipine caused a slight increase (66 +/- 2 to 70 +/- 2 bpm; P < 0.001 between drugs) and tended to increase cardiac output. Noradrenaline spillover increased similarly with the two drugs, from 3.44 +/- 0.27 to 5.20 +/- 0.48 nmol/min per m2(P < 0.01) during mibefradil and to 5.72 +/- 0.49 nmol/min per m2 (P < 0.001) during amlodipine. There were minor effects on cardiac sympatho-vagal balance, but systolic and diastolic myocardial velocities were increased similarly by both drugs.

CONCLUSIONS

Mibefradil and amlodipine treatment increase global sympathetic nerve activity similarly during long-term treatment, despite opposite effects on heart rate. Increases in myocardial velocities suggest concomitant cardiac sympathetic activation.

The atrioventricular plane displacement as a means of evaluating left ventricular systolic function in acute myocardial infarction

Displacement of the atrioventricular (AV) plane toward the cardiac apex in systole was studied quantitatively by echocardiography in 37 patients with first-time acute myocardial infarction (MI) in order to evaluate left ventricular systolic function. The amplitude of AV plane displacement was recorded from the apex at four different sites corresponding to the septal, lateral, anterior, and posterior walls of the left ventricle from apical 4- and 2-chamber views. The patients had a decreased displacement of the AV plane compared with controls which was more pronounced at the sites of infarction. The mean value of the AV plane displacement (AV mean) correlated linearly with the left ventricular (LV) ejection fraction calculated by radionuclide angiography (r = 0.87, p less than 0.001, SEE = 6.2). An AV mean of 10 mm or more had a high sensitivity (95%) and specificity (82%) in defining a normal ejection fraction (greater than or equal to 50%). A high correlation coefficient was found between LV wall motion index and the AV plane displacement. Thus, in acute MI the LV function can be assessed noninvasively using AV plane displacement.