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Published on: August 2, 2019
Ventricular function after normothermic versus hypothermic cardioplegia
T M Yau1, J S Ikonomidis, R D Weisel
1Division of Cardiovascular Surgery, Toronto Hospital, Ontario, Canada.
Insights
Warm cardioplegia improved postoperative left ventricular function compared to cold cardioplegia. This cardiac surgery technique enhanced systolic function and early diastolic relaxation, suggesting better myocardial protection.
Area of Science:
- Cardiovascular Surgery
- Cardiac Anesthesia
- Cardiomyocyte Physiology
Background:
- Traditional cold intermittent cardioplegia is standard in cardiac surgery.
- The impact of warm cardioplegia on postoperative left ventricular function remains unclear.
Purpose of the Study:
- To compare the effects of warm versus cold blood cardioplegia on ventricular function.
- To evaluate load-independent indices of ventricular function post-cardiac surgery.
Main Methods:
- Randomized clinical trial involving 53 patients undergoing cardiac surgery.
- Assessment of myocardial metabolism (oxygen consumption, lactate, adenine nucleotides).
- Measurement of left ventricular function using pressure-volume loops 3 hours post-operation.
Main Results:
- Warm cardioplegia showed improved recovery of myocardial oxygen consumption and reduced creatine kinase MB isoenzyme release.
- Patients receiving warm cardioplegia exhibited increased end-systolic elastance and preload-recruitable stroke work index.
- Enhanced early diastolic relaxation was observed in the warm cardioplegia group.
Conclusions:
- Warm blood cardioplegia may offer improved myocardial protection and enhanced postoperative left ventricular systolic and diastolic function.
- Potential benefits may be linked to improved myocardial metabolism, lactate levels, or catecholamine activity.
- Further research is warranted to elucidate the mechanisms behind improved cardiac function with warm cardioplegia.
Abstract:
Warm cardioplegia produced by essentially continuous infusion has been used as an alternative to traditional cold intermittent infusion techniques during cardiac surgery, but its effects on postoperative left ventricular function have not been defined. We performed a randomized clinical trial to assess the effects of warm and cold blood cardioplegia on load-independent indices of ventricular function. Fifty-three patients were randomized to warm (n = 27) or cold (n = 26) cardioplegia. Myocardial oxygen consumption, lactate production, adenine nucleotides, and adenine nucleotide degradation products were measured during cardioplegia and reperfusion. In 13 patients per group, pressure-volume loops were constructed and ventricular function was assessed 3 hours after the operation. Warm cardioplegia resulted in greater myocardial lactate production but improved recovery of oxygen consumption during reperfusion. Depletion of adenosine triphosphate was similar between groups, but total adenine nucleotides (adenosine triphosphate + adenosine diphosphate + adenosine monophosphate) fell further during warm cardioplegia. Cold cardioplegia was associated with an accumulation of adenosine diphosphate and adenosine monophosphate. Creatine kinase MB isoenzyme release was reduced in the warm group. Three hours after the operation, end-systolic elastance and preload-recruitable stroke work index were increased after warm cardioplegia, and early diastolic relaxation was also increased. Increased systolic function after warm cardioplegia may have been related to improved myocardial protection, elevated arterial lactate concentrations, or increased circulating catecholamine levels. Altered diastolic compliance in the warm group may reflect greater active relaxation during early diastolic filling.
