The Annals of Thoracic Surgery, Vol 41, 150-154, Copyright © 1986 by The Society of Thoracic Surgeons
Preservation of myocardial high-energy phosphates with vagal stimulation and hypothermic cardioplegia
JM Levett, JH Ip, MH Kadowaki, CA Stennis and RB Karp
We examined three methods of inducing hypothermic cardioplegic arrest and
related each to preservation of high-energy phosphates. Levels of adenosine
triphosphate (ATP) and creatine phosphate (CP) in baseline rat hearts were
compared with levels found after vagal stimulation combined with
cardioplegia containing 15 mEq of potassium chloride (KCl) per liter,
cardioplegia with 15 mEq of KCl per liter alone, and cardioplegia with 30
mEq of KCl per liter alone. Vagal stimulation produced complete
electromechanical arrest in a shorter time than either 15 or 30 mEq of KCl
alone (p less than 0.001 for both cardioplegic solutions compared with
vagal stimulation), with fewer ventricular beats after ischemia than
cardioplegic solution containing 15 or 30 mEq of KCl (p less than 0.001 and
less than 0.01, respectively). Levels of ATP and CP, although less than
baseline levels (p less than 0.01 and less than 0.001, respectively), were
greater with vagal stimulation than with either 15 or 30 mEq of KCl (p less
than 0.001 and less than 0.05, respectively, for ATP and p less than 0.001
for both CP levels). Furthermore, when all groups were combined, ATP and CP
levels were found to correlate negatively with arrest time (r = - 0.851 and
-0.788, respectively; both r values significant at p less than 0.01) and
with the number of ventricular beats after ischemia (r = -0.927 and -0.851,
respectively; both r values significant at p less than 0.01). We conclude
that electromechanical work quantified as time to arrest after aortic
cross-clamping and as number of ventricular beats after ischemia correlates
negatively with ATP and CP levels.(ABSTRACT TRUNCATED AT 250 WORDS)
