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Rapid cooling contracture with cold cardioplegia
J A Lahorra1, D F Torchiana, G Tolis
1Cardiac Surgical Unit, Massachusetts General Hospital, Harvard Medical School, Boston, USA.
The Annals of Thoracic Surgery
|May 1, 1997
Summary
Rapid cooling during cardioplegia increases heart pressure and calcium levels, consuming energy. Avoiding rapid cooling may benefit warm heart surgeries and warm cardioplegic arrest induction.
Area of Science:
- Cardiovascular Surgery
- Cardioplegia Research
- Myocardial Protection
Background:
- Cold cardioplegia can cause rapid cooling contracture.
- The relationship between cooling contracture, myocardial temperature, and myocyte calcium is not well understood.
Purpose of the Study:
- To investigate the effects of different cardioplegia temperatures on myocardial function and intracellular calcium.
- To determine the impact of rapid cooling on myocardial energy consumption and contracture.
Main Methods:
- Rat hearts underwent crystalloid cardioplegia infusions at 4°C, 20°C, and 37°C.
- Intracellular calcium ([Ca2+]i) was measured using Indo-1.
- Hearts also received hypoxic, glucose-free cardioplegia at 4°C or 37°C.
Main Results:
- Cold cardioplegia (4°C and 20°C) significantly increased left ventricular pressure and [Ca2+]i compared to 37°C.
- Coronary flow decreased with colder temperatures.
- Warm induction of arrest reduced the negative effects of subsequent cold cardioplegia.
Conclusions:
- Rapid cooling during cardioplegia increases myocardial workload, intracellular calcium, and coronary resistance, leading to energy depletion.
- Warm heart operations and warm cardioplegic arrest induction may prevent rapid cooling contracture.