Arrhythmogenesis in heart failure

In a rabbit model of heart failure produced by combined pressure and volume overload, nonsustained ventricular tachycardias developed in 15 of 23 fail ing rabbits. Sinus rate was increased in rabbits dying suddenly, but was de creased in survivors. This also was true in isolated preparations. Microele ctrode recordings from ventricular trabeculae both from patients with end-s tage failure and from failing rabbits showed that in half of the preparatio ns, delayed afterdepolarizations and triggered activity occurred, but only in the presence of norepinephrine and a lowered extracellular K+ concentrat ion of 3 mM, This was due to spontaneous release of Ca2+ from the sarcoplas mic reticulum.