Acute induction of sustained ventricular tachycardia: a new porcine model.
In this study we evaluated the possibility of initiating long-lasting ventricular tachycardias acutely, using isolated porcine hearts and thus avoiding an open-chest operation model. This set-up was designed especially to investigate defibrillating or antitachycardiac pacing devices, which terminate these malignant arrhythmias if medical treatment fails. The experiments were performed on 42 pigs, weighing 20-25 kg. After thoracotomy their hearts were removed and adapted to a Langendorff perfusion system. Supplied with their own blood, beating hearts were manipulated in three different ways: direct current impulses (4.5 V, 750 ms) or programmed ventricular stimulation, creation of a small myocardial infarction, and application of antiarrhythmic drugs (ajmalin, lidocaine, sotalol). Out of all possibilities the combination of ajmalin (mean concentration 0.041 micrograms/ml) and a small anteroapical myocardial infarction (3-6 cm2) along with direct current impulses (4.5 V), led to sustained ventricular tachycardias in the highest proportion (93%) of trials (P less than 0.001). The heart rate was 251 beats per minute on average. Lidocaine trials were less successful (53%), while programmed ventricular stimulation and sotalol failed to induce ventricular tachycardias. This study supports the evidence that the combination of ajmalin and a small myocardial infarction with direct current impulses is a reliable model for sustained ventricular tachycardias in isolated pig hearts. Although it is a rather artificial organ model, tachycardias can be induced acutely without any long-term pretreatment. Animal models based on chronic myocardial infarctions will therefore be unnecessary for the investigation of defibrillating systems and antitachycardiac pacing devices.
Schmid
C
C
Dept. of Thoracic and Cardiovascular Surgery, Hannover Medical School, Federal Republic of Germany.
Nitsch
J
J
Lüderitz
B
B
D000818:Animals; D004195:Disease Models, Animal; D004558:Electric Stimulation; D004562:Electrocardiography; D006321:Heart / Q000503:physiopathology; D006352:Heart Ventricles; D008012:Lidocaine / Q000494:pharmacology; D009203:Myocardial Infarction; D013015:Sotalol / Q000494:pharmacology; D013552:Swine; D013610:Tachycardia / Q000503:physiopathology*; D013997:Time Factors; D014693:Ventricular Fibrillation
D008012:Lidocaine; D013015:Sotalol