Effect of the 'specific bradycardic agent' alinidine on the function of ischemic myocardium.
In patients with coronary artery disease, the reduction of heart rate (HR) by beta-blockers can further impair myocardial function by reducing the contractility and coronary perfusion. This is possibly not the case for "specific bradycardic agents" like alinidine (ALI). The effect of ALI on ischemic myocardium, therefore, was studied in anesthetized open-chest dogs measuring left ventricular end-diastolic pressure (LVedP), dP/dt, aortic pressure (AoP) by catheter tip manometers, coronary blood flow (Q) electromagnetically, end-diastolic length (edL) and systolic shortening (sdL in %edL) of ischemic (RISC) and non-ischemic (NISC) wall segments by sonomicrometry. Group A (n = 11): Left coronary artery constriction to reduce Q (-53%) and poststenotic sdL (-54%), then i.v. injection of ALI (0.25 + 0.25 + 0.5 + 1.0 mg/kg), thereafter atrial pacing at HR before ALI. Group B (n = 9): Installation of an aorto-coronary bypass, pump-perfused at 50% of free flow, infusion of ALI into the bypass. The results showed that ALI iv dose-dependently reduced HR from 135/min to 90/min, LVedP rose from 8.6 to 10.0 mmHg and NISC-edL from 14.1 to 14.6 mm indicating increased ventricular filling. Non-ischemic systolic shortening did not change. Ischemic systolic shortening was improved from 9.2% to 17.5%, which was not due to an increase in RISC-edL (14.8 versus 14.7 mm), enhanced RISC-Q (13 versus 12 ml/min), reduced AoP (86 versus 84 mmHg) or change in inotropy (dP/dtmax: 2290 versus 2240 mmhg/s), but the increase in RISC-sdl correlated closely (r greater than 0.85) to the reduction in HR (oxygen-demand).(ABSTRACT TRUNCATED AT 250 WORDS)
Schad
H
H
Department of Cardiac and Vascular Surgery, German Heart Center, Munich.
Heimisch
W
W
Haas
F
F
Mendler
N
N
D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D002317:Cardiovascular Agents / Q000494:pharmacology*; D003000:Clonidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D003326:Coronary Circulation / Q000187:drug effects; D003327:Coronary Disease / Q000503:physiopathology*; D004285:Dogs; D005260:Female; D006321:Heart / Q000187:drug effects* / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D008297:Male
D000889:Anti-Arrhythmia Agents; D002317:Cardiovascular Agents; C022192:alinidine; D003000:Clonidine