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Myocardial dysfunction after resuscitation from cardiac arrest: an example of global myocardial stunning
K B Kern1, R W Hilwig, K H Rhee
1Department of Medicine, University of Arizona, Tucson 85724, USA.
Insights
Prolonged cardiac arrest and resuscitation cause severe heart dysfunction, but function returns to normal within 48 hours in this animal model.
Area of Science:
- Cardiology
- Critical Care Medicine
- Experimental Physiology
Background:
- Cardiac arrest (CA) from ventricular fibrillation (VF) halts blood flow, including to the myocardium.
- Cardiopulmonary resuscitation (CPR) provides suboptimal myocardial blood flow.
- Post-resuscitation myocardial stunning, a reversible dysfunction, can occur after successful resuscitation, but its extent and duration are unclear.
Purpose of the Study:
- To investigate the impact of prolonged cardiac arrest and subsequent cardiopulmonary resuscitation on left ventricular systolic and diastolic function.
- To determine the time course of myocardial stunning following successful resuscitation from cardiac arrest.
Main Methods:
- Twenty-eight domestic swine underwent 10 or 15 minutes of untreated cardiac arrest followed by resuscitation.
- Invasive (left ventriculograms, ventricular pressures, cardiac output) and noninvasive (transthoracic Doppler-echocardiography) measurements assessed ventricular function.
- Key parameters included ejection fraction, regional wall motion, end-diastolic pressure, and isovolumetric relaxation time (tau).
Main Results:
- Twenty-three animals were successfully resuscitated.
- Significant reductions in left ventricular ejection fraction and fractional shortening were observed post-resuscitation.
- Global systolic dysfunction and impaired diastolic function (increased isovolumetric relaxation time) were evident.
- Myocardial function began improving by 24 hours and returned to baseline by 48 hours post-resuscitation.
Conclusions:
- Severe myocardial systolic and diastolic dysfunction occurs after 10-15 minutes of cardiac arrest and resuscitation.
- This post-resuscitation myocardial stunning is fully reversible, with recovery observed by 48 hours in this experimental model.
- Findings highlight the significant but transient impact of cardiac arrest and CPR on cardiac function.
Objectives:
This study investigated the effect of prolonged cardiac arrest and subsequent cardiopulmonary resuscitation on left ventricular systolic and diastolic function.
Background:
Cardiac arrest from ventricular fibrillation results in cessation of forward blood flow, including myocardial blood flow. During cardiopulmonary resuscitation, myocardial blood flow remains suboptimal. Once the heart is defibrillated and successful resuscitation achieved, reversible myocardial dysfunction, or "stunning," may occur. The magnitude and time course of myocardial stunning from cardiac arrest is unknown.
Methods:
Twenty-eight domestic swine (26 +/- 1 kg) were studied with both invasive and noninvasive measurements of ventricular function before and after 10 or 15 min of untreated cardiac arrest. Contrast left ventriculograms, ventricular pressures, cardiac output, isovolumetric relaxation time (tau) and transthoracic Doppler-echocardiographic studies were obtained.
Results:
Twenty-three of 28 animals were successfully resuscitated and postresuscitation 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 systolic dysfunction. Left ventricular end-diastolic pressure increased significantly in the postresuscitation period (p < 0.05). Isovolumetric relaxation time (tau) was significantly increased over baseline by 2 h after resuscitation (p < 0.05). Similar findings were noted with the Doppler-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 24 h, these invasive and noninvasive variables of systolic and diastolic left ventricular function had begun to improve. At 48 h, all measures of left ventricular function had returned to baseline levels.
Conclusions:
Myocardial systolic and diastolic dysfunction is severe after 10 to 15 min of untreated cardiac arrest and successful resuscitation. Full recovery of this postresuscitation myocardial stunning is seen by 48 h in this experimental model of ventricular fibrillation cardiac arrest.