Cardiac anaphylaxis in isolated working guinea pig heart

Three distinct phases of response were seen after antigen challenge in isolated working guinea pig heart sensitized with crystallized ovalbumin: 1) Phase of augmcntation, characterizcd by sinus tachycardia and augmentation of cardiac function parameters; 2) Phase of arrhythmias, characterized by severe arrhythmias, decrease of coronary flow, and attenuation of cardiac functions; 3) Phase of recovery, characterized by the recovcry of sinus thythm and progressive decrease of the pump function. These results strongly demonstrate that the sequence of events during cardiac anaphylaxis are connected with the direct action of mediators released (histamine and other bioactive endogenous substances) on the heart solely, independent of pulmonary distress and peripheral vasomotor collapse.