[Show abstract][Hide abstract]ABSTRACT: Retrograde warm blood cardioplegia is now recognized as an effective method of myocardial protection, but concerns persist about its ability to adequately preserve the right ventricle.
A total of 75 patients in whom warm blood cardioplegia was continuously given through the coronary sinus were included in this three-part study. Part 1, which involved 30 patients undergoing coronary artery bypass grafting operations, was designed to assess whether the right ventricle incurred a greater degree of anaerobic metabolism than the left ventricle during warm arrest. Immediately before aortic unclamping, antegrade perfusion was resumed and, within 1 minute of washout, blood samples were simultaneously taken from the right ventricle and coronary sinus and assayed for lactate. There was no significant difference in lactate concentrations between the two sampling sites (right ventricle, 2.53 +/- 0.1 mmol/L; coronary sinus, 2.47 +/- 0.1 mmol/L). Part 2 focused on recovery of function. A complete set of postoperative hemodynamic measurements was obtained in 15 among the 30 patients enrolled in part 1 and compared with that obtained in 15 case-matched patients who received conventional cold antegrade crystalloid cardioplegia. Postoperative right ventricular stroke work index was not significantly different between the two groups (retrograde warm, 4.6 +/- 0.2 g.m-1.m-2; antegrade cold, 4.8 +/- 0.2 g.m-1.m-2). Part 3 was also targeted at functional end points but in 30 additional patients undergoing reoperative mitral valve replacement and consequently deemed to be at higher risk of right ventricular ischemia. Fifteen patients who received retrograde warm cardioplegia were compared with 15 case-matched control subjects in whom antegrade cold crystalloid cardioplegia was used. In keeping with data of part 3, postoperative right ventricular stroke work index was not significantly different between the two groups (retrograde warm, 6.9 +/- 0.4 g.m-1.m-2; antegrade cold, 7.7 +/- 0.5 g.m-1.m-2), nor was there a difference in clinical outcomes or biological recoveries of hepatic function.
Inadequate protection of the right ventricle associated with the use of retrograde warm blood cardioplegia does not appear to be a clinically founded concern since this technique preserves right ventricular function to the same extent as conventional antegrade cold cardioplegia does.
[Show abstract][Hide abstract]ABSTRACT: Peripheral vasodilation is commonly seen during and after warm heart operations and can become of clinical concern when it requires vasopressors because some of these drugs adversely affect coronary artery bypass graft flows. As hemodilution lowers systemic vascular resistance, we assessed whether peripheral vasodilation could be limited by a drastic reduction of the volume of infused cardioplegia. Fifty patients underwent isolated coronary artery bypass grafting procedures using normothermic (35 degrees to 37 degrees C) bypass and normothermic continuous retrograde blood cardioplegia. They were divided into two equal groups: in group 1, blood was diluted 4:1 with hyperkalemic crystalloid cardioplegia, whereas in group 2, the cardioplegic "solution" was limited to the sole arresting agents that were concentrated in a small volume (16 mEq potassium chloride and 3 mEq magnesium chloride in a 20-mL ampoule). This "mini-cardioplegia" was continuously added to arterial blood so as to keep the heart arrested. The average volume of cardioplegia per patient was 1,000 mL in group 1 and 58 mL in group 2 (p < 0.0001). The mini-cardioplegia technique resulted in a reduced incidence of perioperative systemic vasodilation: group 2 patients required significantly less vasopressors (p < 0.05) and less volume loading, as reflected by significantly lower right atrial and pulmonary capillary wedge pressures (p < 0.05 and p < 0.03 at 12 hours postoperatively, respectively), compared with group 1 patients who received traditional high-volume cardioplegia. There were no differences between the two groups with respect to myocardial recovery, as assessed by standard clinical and hemodynamic end points.(ABSTRACT TRUNCATED AT 250 WORDS)
Article · Dec 1993 · The Annals of Thoracic Surgery
[Show abstract][Hide abstract]ABSTRACT: This study was designed to assess whether an oxygenated fluorocarbon solution could reduce ischemie brain damage related to arterial air embolism. Air embolism was produced by injecting air bubbles into the carotid artery of barbiturate-anesthetized rats breathing 100% oxygen. Results were assessed on electrocorticogram. In an additional set of experiments, mass spectrometry was used to provide continuous monitoring of intracerebral tissue oxygen (Po2) and carbon dioxide (Pco2) tensions and intermittent measurement of cerebral blood flow (CBF). Fluorocarbon or saline solution (containing the emulsifying agent of fluorocarbons) was given intravenously after the initial air embolism (0.2 ml), and injections of air (0.1 ml) were repeated thereafter every five minutes. The maximal amount of air required to achieve complete and irreversible flattening of the electrocorticogram was 1.60 ± 0.06 ml (mean ± standard error of the mean) in the saline-treated rats and 5.20 ± 0.44 ml in the fluorocarbon-treated group (p < 10-7). In the second experiment, air embolism caused CBF to rise in both groups, the average percent of increase being higher in treated (41.6%) than in control animals (38.3%) (p < 0.02). However, in the control group, the increase in CBF did not prevent intracerebral tissue Po2 from decreasing by 7.4 ± 7.0% over the same period; conversely, in the fluorocarbon group, Po2 levels fell by only 2.5 ± 3.7% (p < 0.001 versus controls), but this time-averaged percentage was calculated over a longer period of cumulative ischemia because of the greater number of air emboli tolerated by treated animals. We conclude that fluorocarbons seem to be effective in extending the tolerance of the brain to ischemic damage secondary to air embolism. Their protective mechanism most likely involves increased availability of oxygen for ischemic tissues and possibly indirect reduction of the size of air bubbles through enhanced denitrogenation of blood.
Article · Sep 1992 · The Annals of Thoracic Surgery
[Show abstract][Hide abstract]ABSTRACT: Age over 70 years and critical stenosis of the left main coronary arterytrunk are two situations in which the use of the internal
mammary arteryhas been questioned. Because the coexistence of these two conditions isincreasingly seen, we reviewed our experience
with 53 patients 70 years ofage or older that underwent myocardial revascularization for left maindisease. In 17 patients,
the left anterior descending coronary artery wasgrafted with the left internal mammary artery whereas the 36 remainingpatients
were exclusively revascularized by means of saphenous veinconduits. There was no significant difference in postoperative mortality
ormorbidity between the two patient groups. We conclude that elderly patientswith left main disease should be offered the
benefits of a mammary arterygraft provided they are hemodynamically stable.
Article · Feb 1992 · European Journal of Cardio-Thoracic Surgery