Computerized M-mode echocardiography in the assessment of cardiovascular effects during intravenous administration of...

Antianginal and antiarrhythmic long term therapy with amiodarone may be associated with side effects, therefore it should be used mainly in short term treatment of severe arrhythmias and acute coronary insufficiency. It is important to assess if any inotropic effect may be produced after intravenous administration of this drug in commonly accepted therapeutic doses (5 mg/kg body weight). To investigate this possibility we studied the effects of amiodarone on blood pressure (BP), on heart rate (HR) and on the maximal velocity of circumferential fiber shortening (Vcf Max). Simultaneous echocardiogram (UCG), electrocardiogram (lead DII) (ECG) and BP cuff measurement were performed on 12 subjects without cardiomegaly and clinical evidence of heart failure, immediately before a 30 second intravenous injection of amiodarone and every 30 seconds over a period of 6 minutes after drug administration. Amiodarone administration markedly raised HR within the first 30 seconds from the beginning of the injection and concomitantly decreased diastolic BP. No significant lowering of systolic BP was observed. Vcf Max (circ/sec) raised during the test concomitantly with HR increase, showing a significant relationship between left ventricular performance and HR. The same was also true during atrial pacing performed on one subject. No significant changes in any of the parameters studied were demonstrated after placebo (saline solution) administration to two presumable healthy subjects. Amiodarone does not seem to have any positive or negative intrinsic inotropic effect when administered intravenously at a dose of 5 mg/kg body weight.