European Journal of Cardio-Thoracic Surgery, Vol 3, 335-345, Copyright © 1989 by European Association for Cardio-thoracic Surgery
Systolic and diastolic interaction in the assessment of left ventricular function following surgical cardioplegia
BM Fabri, IB Krisch, PJ La Raia and MJ Buckley
Regional Adult Cardiothoracic Unit, Broadgreen Hospital, Liverpool, UK.
Using regionally implanted sonomicrometry crystals, we have evaluated a new
index of regional function (normalised systolic shortening [NSS]) which
integrates the systolic and diastolic properties of the left ventricle.
Eight dogs (group I) were subjected to standard cardiopulmonary bypass and
45 min of hypothermic (10 degrees C), hyperkalaemic (25 mEq) crystalloid
cardioplegia. Seven dogs (group II) underwent occlusion of the left
anterior descending (LAD) coronary artery 5 min prior to initiation of
cardiac arrest. The occlusion was released after 20 min, before the second
cardioplegia infusion. Sarnoff left ventricular (LV) function curves were
performed pre-arrest and 20, 40 and 60 min after removal of the
cross-clamp. Regional assessment of myocardial function showed 55% +/- 3%,
70% +/- 3% and 70% +/- 5% recovery in the LAD region and 52% +/- 2%, 83%
+/- 3% and 88% +/- 4% recovery in the circumflex (Cx) region of group I. In
group II the LAD region recovered 27% +/- 1%, 31% +/- 3% and 38% +/- 3% and
the Cx region showed 61% +/- 3%, 55% +/- 1% and 65% +/- 5% recovery.
Comparison of the new index of ventricular function to standard indices of
regional and global function demonstrate that the latter underestimate the
degree of myocardial dysfunction after cardioplegic arrest, particularly in
situations of acute regional myocardial ischaemia and uneven myocardial
protection. The utilization of this index should provide a better standard
for the more accurate assessment of interventions designed to decrease
myocardial injury during cardioplegic arrest.
