Related Experiment Video
Updated: Sep 11, 2026
Murine Isolated Heart Model of Myocardial Stunning Associated with Cardioplegic Arrest
Published on: August 6, 2015
Ischemic tolerance of the arrested heart during warm cardioplegia
1Department of Surgery, New York Hospital, Cornell University Medical College, NY 10021.
Insights
Normothermic blood cardioplegia offers myocardial protection during cardiopulmonary bypass. Intermittent cardioplegia every 5 minutes maintained systolic function, while every 10 minutes impaired both systolic and diastolic functions.
Area of Science:
- Cardiovascular Surgery
- Cardiac Anesthesia
- Myocardial Protection
Background:
- Normothermic blood cardioplegia is a developing technique for myocardial protection during cardiopulmonary bypass (CPB).
- A key challenge is maintaining myocardial health during the obligatory interruption of coronary flow for distal coronary anastomosis.
Purpose of the Study:
- To determine the safe duration of normothermic ischemic time for an arrested and decompressed heart during CPB.
- To evaluate the impact of different intermittent warm blood cardioplegia strategies on cardiac function.
Main Methods:
- Twenty-one adult dogs were subjected to normothermic CPB (37°C).
- Initial cardioplegic arrest was induced with warm hyperkalemic blood cardioplegia.
- Hearts received continuous, intermittent (every 5 min), or intermittent (every 10 min) warm blood cardioplegia for 30 minutes of ischemic time.
- Left ventricular pressure-volume loops were analyzed using micromanometer and conductance catheters to assess systolic and diastolic function.
Main Results:
- The group receiving cardioplegia every 5 minutes showed minor diastolic function deterioration but maintained systolic function.
- The group receiving cardioplegia every 10 minutes experienced significant reductions in both diastolic and systolic functions.
- Septal wall pH dropped significantly in the intermittent groups, particularly in the every 10 minutes group.
Conclusions:
- Intermittent normothermic blood cardioplegia every 5 minutes appears to be a safe strategy for myocardial protection during CPB.
- Prolonged intervals (every 10 minutes) of normothermic ischemia can compromise cardiac function.
- Further research is needed to optimize cardioplegia delivery for extended surgical procedures.
Abstract:
Normothermic blood cardioplegia has recently generated interest as an alternative method of myocardial protection during cardiopulmonary bypass (CPB) surgery. One disadvantage is the obligatory interruption of coronary flow during the distal coronary anastomosis. This study was designed to determine the safe normothermic ischemic time of the arrested and decompressed heart. Under normothermic CPB (37 degrees C), initial cardioplegic arrest was induced with 750 cc of warm (37 degrees C) hyperkalemic blood cardioplegia in 21 adult dogs. The heart then received warm blood cardioplegia either continuously (50 cc/min), every 5 min (250 cc each) or every 10 min (350 cc each) for a total equivalent ischemic time of 30 min (n = 7 in each group). Left ventricular pressure-volume (PV) loops were measured by micromanometer and conductance (volume) catheters before, at 60 and 90 min after aortic cross-clamping. Systolic function was measured as the preload recruitable stroke work area derived from the stroke work-end diastolic volume relationship, and the diastolic stiffness constant (k) was derived from the exponential diastolic PV relationship. The q5 min group sustained minor deterioration in diastolic function while its systolic function was well maintained during recovery. There were significant reductions in both the diastolic and systolic functions in the q10 min group. The maximum drops in the septal wall pH during aortic cross-clamping were 0.05 +/- 0.02 (not significant), 0.19 +/- 0.06 (P < 0.05), and 0.40 +/- 0.09 (P < 0.01) for the continuous, q5 min and q10 min groups, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
