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Influence of diltiazem on cardiac function at organ and molecular level during hypothermic cardiac arrest
1Department of Physiology and Cardiovascular Surgery, College of Medicine, University of Saskatchewan, Saskatoon.
Insights
Cold crystalloid cardioplegia impairs heart function and calcium uptake. Adding diltiazem improves myocardial contractility and reduces injury during cardiac arrest recovery.
Area of Science:
- Cardiology
- Cardiovascular Surgery
- Biochemistry
Background:
- Cold crystalloid cardioplegia is used to protect the heart during cardiac arrest.
- The effects of diltiazem on myocardial recovery after ischemia are not fully understood.
Purpose of the Study:
- To evaluate the impact of cold crystalloid cardioplegia, with and without diltiazem, on cardiac function.
- To assess effects on sarcoplasmic reticulum calcium handling and myocardial injury markers.
Main Methods:
- Dogs underwent 1 hour of ischemic cardiac arrest followed by 1.5 hours of reperfusion.
- Groups received sham bypass, cold crystalloid cardioplegia, or cardioplegia with diltiazem.
- Cardiac contractility, sarcoplasmic reticulum function, and MB fraction of creatine kinase (MBCK) were measured.
Main Results:
- Cold crystalloid cardioplegia decreased cardiac contractility and sarcoplasmic reticulum calcium uptake.
- Diltiazem partially preserved myocardial contractility and showed a trend towards improved calcium uptake.
- Diltiazem reduced MBCK release, indicating less myocardial injury.
Conclusions:
- Cold crystalloid cardioplegia impairs cardiac function and calcium handling.
- Diltiazem offers a protective effect against ischemic and reperfusion injury.
- Diltiazem may improve functional recovery by modulating calcium uptake mechanisms.
Abstract:
The present study was undertaken to assess the effects of cold crystalloid cardioplegia with and without diltiazem on the functional recovery of the heart, calcium binding and uptake by the sarcoplasmic reticulum, Ca++ATPase of sarcoplasmic reticulum and coronary sinus serum MBCK (MB fraction of creatine kinase) of dogs, after 1.5 h of reperfusion following 1 h of ischemic cardiac arrest. The dogs were divided into three groups: group I, sham bypass (no ischemic cardiac arrest); group II, cold crystalloid cardioplegia; group III, cold crystalloid cardioplegia with diltiazem. The results showed that the decrease in the index of cardiac contractility and cardiac index which accompanies cold crystalloid cardioplegia is associated with a decrease in the calcium uptake by sarcoplasmic reticulum. The index of myocardial contractility was better preserved with cold crystalloid plus diltiazem than with cold crystalloid alone. This improvement, although partial, in cardiac contractility with cold crystalloid plus diltiazem, was associated with a tendency for an increase towards control values in the calcium uptake by sarcoplasmic reticulum. There were no changes in Ca++ATPase of, and calcium binding by, the sarcoplasmic reticulum of groups II and III when compared to group I. There was a progressive increase in the MBCK of coronary sinus blood in groups II and III. The MBCK of group I was unchanged throughout the experimental protocol. The increases in the MBCK of coronary sinus blood were less in group III than in group II indicating the protective effect of diltiazem on ischemic and reperfusion myocardial injury.(ABSTRACT TRUNCATED AT 250 WORDS)