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Multicentre investigation of myocardial protection with cold cardioplegia
Insights
Optimizing myocardial protection during open-heart surgery involves managing aortic occlusion time and myocardial temperature. Lower temperatures and shorter occlusion times significantly reduce postoperative complications like conduction disturbances and enzyme release.
Area of Science:
- Cardiology
- Cardiac Surgery
- Cardiovascular Research
Background:
- Myocardial protection is crucial during open-heart surgery.
- Various cardioplegic techniques exist, but their comparative efficacy requires further analysis.
- Assessing protection efficiency is key to improving patient outcomes.
Purpose of the Study:
- To analyze factors influencing myocardial protection efficiency in isolated aortic valve replacement.
- To evaluate the impact of different cardioplegic techniques and operative parameters.
- To identify optimal strategies for minimizing myocardial damage during surgery.
Main Methods:
- Study of 144 patients undergoing isolated aortic valve replacement.
- Comparison of cardioplegic techniques: Bretschneider, St. Thomas, Ringer-potassium, and blood cardioplegia (single/multi-dose and continuous).
- Assessment of myocardial protection via postoperative conduction disturbances, enzyme release (CK-MB), and inotropic support requirements.
Main Results:
- Aortic occlusion duration and myocardial temperature were critical factors.
- Longer aortic occlusion (>80 min) correlated with higher conduction disturbances (32%) and enzyme release.
- Myocardial temperatures below 18°C consistently showed low enzyme activities, indicating effective protection.
Conclusions:
- Optimal myocardial protection is achieved with hypothermia (25-27°C), single/multi-dose blood cardioplegia, and efficient local cardiac cooling.
- Minimizing aortic occlusion time and maintaining low myocardial temperatures are paramount for reducing postoperative complications.
- Preoperative risk factors had minimal impact compared to intraoperative management strategies.
Abstract:
In order to analyze factors of importance for the efficiency of myocardial protection during open-heart surgery, a study was made of 144 patients undergoing isolated aortic valve replacement with various cardioplegic techniques. The cardioplegia was of Bretschneider type in 54 cases, St Thomas in 31 and Ringer-potassium type in 11 cases. Single or multi-dose blood cardioplegia was used in 11 cases and continuous blood cardioplegia in 30 cases. Local cardiac hypothermia was additionally employed in all patients. The efficiency of myocardial protection was assessed mainly from the incidence of postoperative conduction disturbances, myocardial enzyme release and need for inotropic support. All patients survived the operation. In 20% surgery was followed by transient or persistent disturbance of conduction, in 9% by abnormally increased CK-MB release and in 5% by requirement for inotropic support. Preoperative risk factors such as high age or severe left ventricular (LV) hypertrophy or dysfunction had little influence on the results. Patients in whom aortic stenosis (AS) was dominant in the complex with aortic insufficiency (AS + AI) showed 20-hour postoperative CK-MB enzyme activity twice as high as those with pure aortic insufficiency. The most important factors in myocardial protection were the duration of aortic occlusion and the myocardial temperature during cardioplegia. When the aortic occlusion lasted more than 80 min there was a 32% incidence of conduction disturbances and 20-hour CK-MB activity thrice as high as after shorter occlusion. Patients with mean myocardial temperature below 18 degrees C during cardioplegia invariably had low enzyme activities, which indicated good myocardial protection. The best overall results were obtained in patients operated on during hypothermia at 25-27 degrees C, with single or multi-dose blood cardioplegia and with efficient local cooling of the heart.