The distribution pattern of a cold (3-4ºC), crystalloid cardioplegic solution (CS) in the myocardium was studied in 15 mongrel dogs, with 10-15 kg of body weight. Alter anesthesia and median sternal thoracotomy. The pericardium was opened and extracorporeal circulation established. The following routes were employed for cardioplegic perfusion: 1) Antegrade - through ascending aortic canullation bellow the aortic occlusion clamp;2) Selective retrograde - through coronary synus (Co.S - 25 mmHg) using a self-inflating ballooned cannula; 3) Total retrograde, (Co.S - 40 mmHg) - through a cannula inserted in the right atrium (RA); 4) Sequencial retrograde, Co.S-RA - with the CS flowing first through the coronary synus lowering the interventricular septal temperature to 16 ºC and after through the RA cannula as in the total retrograde technique with the pulmonary artery occluded and;5) Sequencial retrograde, Co.S-RV - the RV chamber being directly cannulated through the tricuspid valve and perfused, instead of the RA in the latter technique. The temperature variation of the myocardium in the left ventricule (LV), RVt RA and sinus node region (SN) was controlled employing an Omega needle termistor and thermometer. With the antegrade technique (70 mmHg pressure) the most uniform myocardial cooling, the lowest CS volume and perfusion time duration was observed, followed In excelence by the Co.S-RA Sequencial retrograde technique and the Co.S-RV sequencial technique. The present data indicate that sequencial retrograde cardioplegic perfusion techinique is significantly better than the usual Co.S or RA total retrograde technique alone for myocardial protection when compared with the aortic root antegrade perfusion technique.
Heart arrest; Heart arrest; Myocardium; Cardioplegy; Myocardial protection