A New Animal Model of Atrial Flutter

A new, simple and reliable model of atrial flutter utilizing postpericardiotomy pericarditis was developed in the dog. Using a sterile technique, the pericardium was opened by way of a right thoracotomy, Teflon-coated, stainless steel wire electrodes were fixed to three selected sites on the atria and exteriorized, the atrial surfaces were generously dusted with talcum powder and a single layer of gauze was placed on the free left and right atrial walls. The dogs were allowed to recover. Subsequently, the inducibility of atrial flutter and selected electrophysiologic properties of the atria were determined by daily programmed atrial stimulation studies with the dogs in the conscious, nonsedated state. Atrial flutter could be induced in 23 of 25 dogs initially studied. It was sustained (that is, lasting greater than or equal to 5 min) in 17 of the 23. Neither atrial excitability, intraatrial conduction time nor atrial refractoriness determined by pacing and recording from the three fixed sites predicted the inducibility of atrial flutter. One hundred thirty-nine episodes of atrial flutter induced in these 23 dogs were analyzed. The mean sustained atrial flutter cycle length was 131 +/- 20 ms (mean +/- SD) (range 100 to 170); the atrial flutter cycle length was 150 ms or more in 23 episodes, between 120 and 150 ms in 64 episodes and 120 ms or less in 52 episodes. In five dogs, the stability of the atrial flutter cycle length during sustained atrial flutter was studied and shown to be remarkably stable in all five until interrupted by rapid atrial pacing 35 to 95 minutes after its induction.(ABSTRACT TRUNCATED AT 250 WORDS)