[Role of the increased cholinergic activity in prevention of reperfusion-induced arrhythmia in dog experiments].
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Animals↗
Biomedical subjects
D Leosco
Publications and source records attributed to D Leosco.
Use of the epinephrine test in diagnosis of coronary artery disease.
Two-dimensional echocardiographic (2-D echo) and electrocardiographic (ECG) monitoring was performed in 53 patients with anginal chest pain during infusion of physiologic doses of epinephrine. Technically adequate 2-D echo studies were recorded in 45 patients. Of these 45 patients, 35 had significant coronary artery disease. Twenty-two patients showed ECG changes during the test (ECG sensitivity 63%), 13 of whom also showed wall motion abnormalities (2-D echo sensitivity 48.5%). Combined ECG and 2-D echo criteria of a positive test yielded a sensitivity of 74%. None of the 10 patients without coronary artery disease had electrical or mechanical abnormalities during the test (specificity 100%). Thus, the epinephrine test during simultaneous 2-D echo and ECG monitoring is a valid alternative to echocardiographic exercise stress testing. Furthermore, the adequate images obtained during the infusion allow better investigation of relation between wall motion abnormalities and ECG changes during myocardial ischemia.
Adult↗
Two-dimensional echocardiographic evaluation of ventricular asynergy induced by dipyridamole: correlation with thallium scanning.
Myocardial asynergies detected by two-dimensional echocardiography during intravenous administration of Dipyridamole (0.75 mg/kg) were evaluated in 54 patients referred for angiographic evaluation of chest pain. Technically adequate two-dimensional echocardiograms suitable for analysis were recorded in 42 of 54 (77.7%) patients studied. Thallium-201 myocardial perfusion scintigraphy, during dipyridamole test was performed in the same patients. Thirty of the 42 patients studied showed significant coronary narrowing at cardiac catheterization. Dipyridamole-induced wall motion abnormalities and myocardial perfusion defects were detected, respectively, in 19 (63.3%) and 21 (70%) of 30 patients with significant coronary artery disease. Wall by wall comparison of the distribution of dipyridamole-induced echocardiographic asynergy with reversible thallium-201 (201Tl) perfusion defects demonstrated complete correlation in 42 segments examined. Three segments with perfusion defects at thallium scanning did not show asynergy during the test while two segments showing wall motion abnormalities during dipyridamole infusion did not manifest perfusion defects. Our study demonstrates that two-dimensional echocardiography during dipyridamole testing is useful in detecting patients with coronary artery disease. Furthermore, ventricular asynergies detected during the test show a high correspondence with site of myocardial perfusion defects at thallium scanning.
Cardiac Catheterization↗
[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.
Adult↗
Effect of mexiletine on reperfusion-induced ventricular arrhythmias: comparison with lidocaine.
Thirty mongrel dogs underwent proximal occlusion of the left anterior descending coronary artery to evaluate the comparative action of mexiletine and lidocaine on ventricular arrhythmias during myocardial reperfusion. Heart rate, arterial blood pressure, left ventricular end-diastolic pressure and dp/dt max were evaluated before and at the 20th and 25th min after coronary occlusion; at the 25th min coronary occlusion was removed. Dogs were randomly assigned to one of the following groups of 10: 1) control group; 2) dogs given i.v. mexiletine; 3) dogs given i.v. lidocaine. As expected, during ischemia, myocardial contractility decreased after mexiletine or lidocaine administration more than in the control group. Ventricular arrhythmias during myocardial reperfusion occurred in 9 dogs of the control group (ventricular tachycardia in 2 cases and ventricular fibrillation in 7 cases). Among dogs given mexiletine only 1 had ventricular fibrillation (p less than 0.001 vs control). Six of the 10 dogs given lidocaine had ventricular arrhythmias (ventricular tachycardia in 5 cases and ventricular fibrillation in 1 case) (p = ns vs control group; p less than 0.05 vs mexiletine group). Thus mexiletine and lidocaine had similar effects on cardiac function during myocardial ischemia and only mexiletine showed a protective effect against reperfusion ventricular arrhythmias.
Animals↗
Effect of flecainide acetate on reperfusion- and barium-induced ventricular tachyarrhythmias in the isolated perfused rat heart.
Flecainide acetate is a new antiarrhythmic drug which suppresses different kinds of experimental arrhythmias. We studied the efficacy of flecainide acetate on reperfusion- and barium-induced ventricular tachyarrhythmias in the isolated perfused rat heart by monitoring heart rate, coronary flow rate, left ventricular systolic pressure, dp/dtmax, and the voltage of the epicardial electrogram. Seventy-five male rats were randomized into 5 groups. In group I, after a 15 min period of stabilization, hearts were perfused by ischemic perfusion and then reperfused. In group II, flecainide acetate (10(-6) M) was given after stabilization and before ischaemic perfusion. In group III, barium chloride (10(-3) M) was given after stabilization. In group IV, flecainide acetate was given after stabilization and before barium chloride administration. In group V, acetylcholine chloride (10(-6) M) was given after stabilization and before barium chloride administration. In group I, we noted during ischemia a reduction in heart rate, coronary flow rate, left ventricular systolic pressure and dp/dtmax and an increase in the voltage of the epicardial electrogram. In group II, after administration of flecainide acetate, we observed a reduction in heart rate, left ventricular systolic pressure and dp/dtmax; during the ischaemic period there was no difference in these parameters with respect to group I. Reperfusion induced ventricular arrhythmias in 12 out of 15 hearts in group I and in only 3 out of 15 in group II (p less than 0.005). Barium induced ventricular arrhythmias in the 15 hearts studied in group III as well as in group IV. On the contrary, acetylcholine chloride in group V prevented the occurrence of barium-induced ventricular arrhythmias (p less than 0.005 vs group III and IV). Thus, flecainide acetate is able to reduce reperfusion-induced ventricular arrhythmias, but is unable to reduce barium-induced ventricular arrhythmias, presumably because of a different mechanism of these two types of arrhythmias.
Animals↗
Electrical and mechanical actions of magnesium sulfate during ischemia and reperfusion on isolated perfused rat heart.
Experimental and clinical studies have shown the action of magnesium salts on myocardial tissue and its antiarrhythmic action on digitalis-induced ventricular arrhythmias. We have evaluated the effects of magnesium sulfate (2.5 mM) on heart rate (HR), coronary flow rate (CFR), left ventricular systolic pressure (LVSP), dP/dt max and voltage epicardial electrogram (VEE) during ischemia and reperfusion in isolated perfused rat heart. Forty-five male rats were randomized into 3 groups. In the control group, after a 15 min period of stabilization, hearts were perfused by ischemic perfusion for 30 min and then reperfused. In group I, magnesium sulfate was given after stabilization and before the ischemic period. In group II, calcium concentration was increased by 0.5 mM and magnesium sulfate was given after stabilization and before the ischemic period. In the control group, we observed during ischemia a reduction in HR, CFR, LVSP, dP/dt max and an increase in VEE. In group I, after the administration of magnesium sulfate, we noted a decrease in HR, LVSP, dP/dt max, VEE and during the ischemic period there was no difference in these parameters with respect to the control group. In group II, the increase of extracellular calcium concentration caused an increase in LVSP, dP/dt max and the administration of magnesium sulfate abolished these effect, bringing the values back to basal values. Reperfusion provoked ventricular arrhythmias in 11/15 and 12/15 hearts in the control group and group II respectively, and only 3/15 in group I (p less than 0.005 group I vs control and group II). Thus, our results demonstrated that magnesium sulfate has varied effects on electrical and mechanical parameters and prevents reperfusion arrhythmias according to the hypothesis of a calcium-antagonist mechanism of magnesium.
Animals↗
[Different prognostic significance of ventricular tachycardia in patients with acute or previous myocardial infarction].
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Female↗