MYOCARDIAL DYSFUNCTION AFTER RESUSCITATION FROM CARDIAC-ARREST - AN EXAMPLE OF GLOBAL MYOCARDIAL STUNNING

Objectives. This study investigated the effect of prolonged cardiac ar rest and subsequent cardiopulmonary resuscitation on left ventricular systolic and diastolic function. Background. Cardiac arrest from ventr icular fibrillation results in cessation of forward blood flow, includ ing myocardial blood flow. During cardiopulmonary resuscitation, myoca rdial blood how remains suboptimal. Once the heart is defibrillated an d successful resuscitation achieved, reversible myocardial dysfunction , or ''stunning,'' may occur. The magnitude and time course of myocard ial stunning from cardiac arrest is unknown. Methods. Twenty-eight dom estic swine (26 +/- 1 kg) were studied with both invasive and noninvas ive measurements of ventricular function before and after 10 or 15 min of untreated cardiac arrest. Contrast left ventriculograms, ventricul ar pressures, cardiac output, isovolumetric relaxation time (tau) and transthoracic Doppler-echocardiographic studies were obtained. Results . Twenty-three of 28 animals were successfully resuscitated and postre suscitation data obtained. Left ventricular ejection fraction showed a significant reduction 30 min after resuscitation (p < 0.05). Regional wall motion analysis revealed diffuse, global left ventricular systol ic dysfunction. Left ventricular end-diastolic pressure increased sign ificantly in the postresuscitation period (p < 0.05). Isovolumetric re laxation time (tan) was significantly increased over baseline by 2 h a fter resuscitation (p < 0.05). Similar findings were noted with the Do ppler-echocardiographic analysis, including a reduction in fractional shortening (p < 0.05), a reduction in mitral valve deceleration time ( p < 0.05) and an increase in left ventricular isovolumetric relaxation time at 5 h after resuscitation (p < 0.05). By 23 h, these invasive a nd noninvasive variables of systolic and diastolic left ventricular fu nction had begun to improve. At 48 h, all measures of left ventricular function had returned to baseline levels. Conclusions. Myocardial sys tolic and diastolic dysfunction is severe after 10 to 15 min of untrea ted cardiac arrest and successful resuscitation. Full recovery of this postresuscitation myocardial stunning is seen by 48 h in this experim ental model of ventricular fibrillation cardiac arrest.