Potassium-channel opener cardioplegia is superior to St. Thomas' solution in the intact animal.
BACKGROUND
In isolated hearts, the potassium-channel opener pinacidil is an effective cardioplegic agent. This study tested the hypothesis that pinacidil is superior to St. Thomas' solution in the more clinically relevant intact animal.


METHODS
Sixteen pigs were placed on full cardiopulmonary bypass. Hearts underwent 2 hours of global ischemia (10 degrees to 15 degrees C). Either St. Thomas' or 100 micromol/L pinacidil was administered every 20 minutes (10 mL/kg). Preischemic and postreperfusion slopes of the preload-recruitable stroke work relationship were determined. Changes in myocardial adenine nucleotide levels and cellular ultrastructure were analyzed.


RESULTS
Pinacidil cardioplegia resulted in an insignificant change in the slope of the preload-recruitable stroke work relationship (40.6+/-2.1 mm Hg/mm before ischemia and 36.5+/-3.7 mm Hg/mm after ischemia; p = 0.466). In contrast, St. Thomas' solution resulted in a significant decrease in the slope after reperfusion (34.3+/-5.5 mm Hg/mm and 13.5+/-2.3 mm Hg/mm; p = 0.003). Adenine nucleotide levels, myocardial tissue water, and ultrastructural changes were similar between groups.


CONCLUSIONS
Pinacidil ameliorated myocardial stunning associated with traditional hyperkalemic cardioplegia without causing significant differences in cellular metabolism.
Section of Cardiothoracic and Vascular Surgery, The Milton S. Hershey Medical Center, Pennsylvania State Geisinger Health System, Hershey 17033, USA.
A M
AM
Jayawant
E R
ER
Stephenson
G S
GS
Matte
G A
GA
Prophet
K F
KF
LaNoue
J W
JW
Griffith
R J
RJ
Damiano
D000227:Adenine Nucleotides / Q000378:metabolism; D000818:Animals; D001639:Bicarbonates; D002122:Calcium Chloride; D002314:Cardioplegic Solutions; D002315:Cardiopulmonary Bypass; D008274:Magnesium; D009200:Myocardial Contraction; D015425:Myocardial Reperfusion; D017682:Myocardial Stunning / Q000378:metabolism / Q000473:pathology; D009206:Myocardium / Q000378:metabolism / Q000648:ultrastructure; D020110:Pinacidil; D015221:Potassium Channels / Q000187:drug effects*; D011189:Potassium Chloride; D012965:Sodium Chloride; D013318:Stroke Volume; D013552:Swine
D000227:Adenine Nucleotides; D001639:Bicarbonates; D002314:Cardioplegic Solutions; D015221:Potassium Channels; C041711:St. Thomas' Hospital cardioplegic solution; D012965:Sodium Chloride; D011189:Potassium Chloride; D020110:Pinacidil; D008274:Magnesium; D002122:Calcium Chloride