The myocardial protective effects of crystalloid, blood, and Fluosol-DA-20% cardioplegia were compared by subjecting hypertrophied pig hearts to 3 hours of hypothermic (10° to 15° C), hyperkalemic (20 mEq/L) cardioplegic arrest and 1 hour of normothermic reperfusion. Left ventricular hypertrophy was created in piglets by banding of the ascending aorta, with increase of the left ventricular weight-body weight ratio from 3.01 ± 0.2 gm/kg (control adult pigs) to 5.50 ± 0.2 gm/kg (p<0.001). An in vivo isolated heart preparation was established in 39 grown banded pigs, which were divided into three groups to receive aerated crystalloid (oxygen tension 141 ± 4 mm Hg), oxygenated blood (oxygen tension 584 ± 41 mm Hg), or oxygenated Fluosol- DA-20% (oxygen tension 586 ± 25 mm Hg) cardioplegic solutions. The use of crystalloid cardioplegia was associated with the following: a low cardioplegia-coronary sinus oxygen content difference (0.6 ± 0.1 vol%), progressive depletion of myocardial creatine phoshate and adenosine triphosphate during cardioplegic arrest, minimal recovery of developed pressure (16% ± 8%) and its first derivative (12% ± 7%), and marked structural deterioration during reperfusion. Enhanced oxygen uptake during cardioplegic infusions was observed with blood cardioplegia (5.0 ± 0.3 vol%), along with excellent preservation of high-energy phosphate stores and significantly improved postischemic left ventricular performance (developed pressure, 54% ± 4%; first derivative of left ventricular pressure, 50% ± 5%). The best results were obtained with Fluosol-DA-20% cardioplegia. This produced high cardioplegia-coronary sinus oxygen content difference (5.8 ± 0.1 vol%), effectively sustained myocardial creatine phosphate and adenosine triphosphate concentrations during the extended interval of arrest, and ensured the greatest hemodynamic recovery (developed pressure, 81% ± 6%, first derivative of left ventricular pressure, 80% ± 10%) and the least adverse morphologic, alterations during reperfusion. It is concluded that oxygenated Fluosol-DA-20% cardioplegia is superior to oxygenated blood and especially aerated crystalloid cardioplegia in protecting the hypertrophied pig myocardium during prolonged aortic clamping.
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine
- Cardiology and Cardiovascular Medicine