Calcium-induced ventricular contraction during cardioplegic arrest

• Published in: The Journal of thoracic and cardiovascular surgery Vol. 94; no. 4; pp. 606 - 613
• Main Authors: Torchiana, DF, Love, TR, Hendren, WG, Geffin, GA, Titus, JS, Redonnett, BE, O'Keefe, DD, Daggett, WM
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA AATS/WTSA 01.10.1987; Elsevier
• Subjects: Adenine Nucleotides - analysis; Anesthesia; Anesthesia depending on type of surgery; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Biological and medical sciences; Blood Pressure - drug effects; Calcium - administration & dosage; Calcium - pharmacology; Cardioplegic Solutions - pharmacology; Dogs; Heart Arrest, Induced; Magnesium - pharmacology; Male; Medical sciences; Myocardial Contraction - drug effects; Myocardium - analysis; Phosphocreatine - analysis; Rats; Rats, Inbred Strains; Thoracic and cardiovascular surgery. Cardiopulmonary bypass; Vascular Resistance - drug effects; Hyperkaliemia; Cardioplegic solution; Vertebrata; Mammalia; Rat; Rodentia; General anesthesia; Experimental study; Induced cardiocirculatory arrest
• ISSN: 0022-5223; 1097-685X
• DOI: 10.1016/s0022-5223(19)36226-9

Cardiac arrest induced by hyperkalemic perfusion is generally considered to represent a state of complete electromechanical arrest. However, high-energy phosphate concentrations and ventricular function decrease with increasing cardioplegic calcium concentrations, possibly because of elevated resting muscle tone produced by calcium influx. We examined isolated rat hearts containing an isovolumic intraventricular balloon for the presence of contractile activity during the administration at 10 degrees C of a cardioplegic solution containing potassium, 20 mEq/L. Significant left ventricular pressure was developed (35.6% +/- 4.3% of prearrest systolic pressure) during administration of a solution containing a calcium concentration of 1.0 mmol/L and far less (9.7% +/- 1.6% of prearrest systolic pressure) with a calcium-free cardioplegic solution. The muscle contraction diminished with repeated doses, was increased by increasing cardioplegic calcium content, and was inhibited by magnesium. Adenosine triphosphate and creatine phosphate concentrations were 9.0 +/- 1.4 and 7.0 +/- 0.9 nmol/mg dry weight immediately after infusion of 15 ml of a hypoxic cardioplegic solution containing calcium, versus 13.3 +/- 1.3 (p less than 0.02) and 31.9 +/- 3.5 nmol/mg dry weight (p less than 0.0001) after a hypoxic acalcemic solution was given. When repeated doses of a hypoxic cardioplegic solution containing calcium in a concentration of 1.0 mmol/L were given at 15 minute intervals at 10 degrees C, ischemic contracture (a sustained development of ventricular pressure, mean 51% +/- 4% of prearrest systolic pressure) resulted within 1 hour. Coronary vascular resistance was increased during the muscle contractions induced by calcium-containing solutions, markedly so during contracture. Calcium-related mechanical activity was also observed during hypothermic cardioplegic arrest in five of six isolated isovolumic canine hearts. We conclude that hearts remain potentially active mechanically during cold hyperkalemic arrest and undergo energetically wasteful contraction when stimulated with calcium-containing hyperkalemic cardioplegic solutions.