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Calcium-induced ventricular contraction during cardioplegic arrest
D F Torchiana1, T R Love, W G Hendren
1Department of Surgery, Massachusetts General Hospital, Boston 02114.
The Journal of Thoracic and Cardiovascular Surgery
|October 1, 1987
Summary
Hearts can remain mechanically active during cold hyperkalemic arrest, with calcium-containing solutions inducing wasteful contractions. This challenges the notion of complete electromechanical arrest in cardiac procedures.
Area of Science:
- Cardiology
- Physiology
- Biochemistry
Background:
- Cardiac arrest via hyperkalemic perfusion is typically viewed as complete electromechanical arrest.
- Elevated calcium in cardioplegic solutions may decrease high-energy phosphate levels and ventricular function due to increased muscle tone.
Purpose of the Study:
- To investigate the presence of contractile activity in isolated rat and canine hearts during cold hyperkalemic cardioplegic arrest.
- To determine the effect of calcium concentration in cardioplegic solutions on myocardial mechanical activity and energy status.
Main Methods:
- Isolated rat and canine hearts with intraventricular balloons were perfused with cold (10°C) hyperkalemic cardioplegic solutions.
- Left ventricular pressure was measured to assess contractile activity.
- Adenosine triphosphate (ATP) and creatine phosphate (CP) concentrations were analyzed after hypoxic perfusion.
Main Results:
- Significant left ventricular pressure developed with calcium-containing solutions (35.6% of prearrest systolic pressure) compared to calcium-free solutions (9.7%).
- Repeated doses of calcium-containing solutions led to diminished contraction and ischemic contracture (51% of prearrest systolic pressure).
- ATP and CP levels were significantly lower after hypoxic perfusion with calcium-containing solutions compared to acalcemic solutions.
Conclusions:
- Hearts retain mechanical activity during cold hyperkalemic arrest.
- Calcium-containing hyperkalemic cardioplegic solutions induce energetically wasteful contractions and impair energy status.
- This mechanical activity and energy expenditure must be considered in cardiac surgical procedures.