INTRAVENOUS ADMINISTRATION OF DILTIAZEM IN THE TREATMENT OF SUPRAVENTRICULAR TACHYARRHYTHMIAS

The aim of the study was to investigate the efficacy of diltiazem bolu s intravenous administration, compared to disopyramide, in the treatme nt of various types of paroxysmal supraventricular tachyarrhythmias. M ethod: Fifty patients (23 males, 27 females, mean age 47.7 +/- 15.2 ye ars) with paroxysmal supraventricular tachyarrhythmia (20 with paroxys mal atrial tachycardia, 23 with paroxysmal atrial fibrillation and rap id ventricular response and 7 with atrial fluttering) were studied. Di ltiazem at a dose of 0.25-0.30 mg/kg BW or disopyramide at a dose of 5 0 mg were given bolus IV. If conversion of the arrhythmia to sinus rhy thm could not be achieved with the initial drug, the alternate was giv en. The order of administration of the drugs was random, independent o f the type of the arrhythmia. Before and during drug administration de tailed clinical examination and frequent blood pressure (BP) measureme nts were performed. Twenty-four how Holter monitoring was done in all patients, starting with the administration of the antiarrhythmic drug. Results. 1) Paroxysmal atrial tachycardia: diltiazem administration c onverted the arrhythmia to sinus rhythm in all patients while disopyra mide in only 1 of 9 patients who received this drug. 2) Paroxysmal aer ial fibrillation: disopyramide converted the arrhythmia in 5 patients without significant change in ventricular response in the others. Dilt iazem did not convert the arrhythmia though it caused significant decr ease in ventricular response (<100 bpm) and in 1 patient an important bradycardia (45 bpm). 3) Atrial fluttering: disopyramide converted the arrhythmia to sinus rhythm in 1 patient without significant change in the ventricular response in the others. Diltiazem caused significant decrease in the ventricular response without conversion to sinus rhyth m. During conversion to sinus rhythm an AV junctional rhythm of short duration (<1 min) was noticed in 5 patients and a short pause (<2 sec) with or without an initial premature contraction in the remaining 21. Disopyramide administration was not associated with side effects. Dil tiazem administration cause small (<20 mm Hg), transient (<30 min) dec rease of BP without symptoms with the exception of the patient with br adycardia in whom the BP decrease was significant (90/60 from 160/80 m m Hg) followed by intense symptoms which lasted for six hours. Conclus ions: Diltiazem administration is extremely effective in conversion of paroxysmal atrial tachycardia to sinus rhythm. In addition it retards ventricular response in patients with atrial fibrillation and flutter ing. Compared to disopyramide these effects of diltiazem are more pron ounced and clinically pertinent.