CAFFEINE AND CARDIAC-ARRHYTHMIAS - AN EXPERIMENTAL-STUDY IN DOGS WITHREVIEW OF LITERATURE

Caffeine and cardiac arrhythmias. An experimental study in dogs with r eview of literature - In spite of widespread belief among clinicians t hat caffeinated drinks are linked with palpitations, tachycardia and d ysrhythmia there is paucity of documentary evidence. We investigated t he arrhythmogenic activity of caffeine in canine model. The alkaloid w as given IV to perform 51 experiments in 13 anesthetized dogs in three different doses. The Low dose generated significant Sinus (S) bradyca rdia (70%; p<0.006, S. arrhythmia (70%; p < 0.02), S. arrest (50%; p < 0.04), Atrial (A) ectopics (40%; p<0.016), Wandering of pacemaker (WP M) (50%; p<0.04), and Ventricular premature contractions (VPC - unifoc al 40%; p<0.05) as compared with control ECGs. Medium dose induced sig nificant S. arrhythmia (62%; p<0.001), A. ectopics (25%; p<0.01), A. t achycardia (25%; p<0.01), WPM (25%; p<0.01), VPCs - unifocal (50%; p<0 .002), multi;focal (25%; p<0.01), couplets (25%; p<0.01) and interpola ted (25%; p<0.0l). High dose of caffeine revealed significant S. arrhy thmia (56%; p<0.002), A. ectopics (44%; p<0.005), A. tachycardia (32%; p<0.01), WPM (32%; p<0.01) and VPCs - unifocal (64%; p<0.001), multif ocal (32%, p<0.01), couplets (32%, p<0.01), interpolated (32%; p<0.01) and Ventricular tachycardia (VT) (20%; p<0.01). A. flutter and fibril lation each were observed in two experiments only. In conclusion, thes e data indicate a dose dependent arrhythmogenecity of caffeine. Small dose, mostly, generated, benign arrhythmias due to vagal stimulation. More severe arrhythmias like VT, multifocal VPC, A. flutter and A. fib rillation were generated with higher dose of caffeine. Mechanism remai ns uncertain as caffeine has multiple actions. Further studies in huma n beings with normal and compromised myocardium may elucidate arrhythm ogenic effects of caffeine.