Hypothermic protection (26-25 degrees C) without perfusion cooling for surgery of congenital cardiac defects using prolonged occlusion.

Abstract

Open heart surgery was performed without perfusion under deep hypothermia in 343 patients with congenital heart defects aged from 1 year 3 months to 44 years. Cooling to a temperature of 26-250C in the oesophagus was achieved by covering the body with crushed ice. The patients were maintained under superficial ether narcosis and they were given morphine (0 5 mg/kg) and tubocurarine (0-5-1l0 mg/kg). The duration of circulatory arrest was 30 minutes in 190 and longer in 153 patients-60-77 minutes in 10 patients. It took an average of7-6 minutes for resumption of normal cardiac activity after circulatory arrest prolonged beyond 60 minutes. Of the 343 patients operated on 32 (9-3%) died. Analysis ofthe mortality pattern showed that patients with acute cardiac insufficiency contributed most to the total number of deaths (19 patients, 5 5%); those with pulmonary oedema ranked second (4 patients, 1 2%) and those with brain oedema third (3 patients, 0-9%). Neurological complications were observed in 13 patients (3-8%). Their frequency was significantly related to the duration of circulatory arrest. Circulatory inadequacy in patients with poor myocardial function who had undergone extensive repair appeared to be a contributory factor. The results obtained without perfusion under deep (26-250C) hypothermic protection suggest that 75 minutes is a safe time, in terms of brain damage, for circulatory arrest. Under these conditions complex cardiac defects can be repaired.

Development of Cardiac Sensitivity to Oxygen Deficiency: Comparative and Ontogenetic Aspects

“…Systemic hypothermia with or without circulatory arrest continues to be used for cardiac protection during pediatric heart surgery; it has been reported that in the neonatal heart, hypothermia permits a "safe" ischemic period for at least 90 min (107). Despite this, clinical studies have reported a 10% mortality using deep (15°C) hypothermia, with 50% of these deaths ascribed to acute cardiac insufficiency (111). It would appear, therefore, that not all hearts are afforded equal protection by hypothermia.…”

Cardiac Surgery under Perfusionless Hypothermia: Siberian Experience

“…This is due to progress in cardiac surgery in general as well as changes we have adopted over the years. 12,13 Due to relatively higher mortality in the group with highrisk congenital heart defects in the past, we now operate on these patients under cardiopulmonary bypass. 12,13 It is apparent that the number of operations has reduced in recent years and this is due to our policy of operating under hypothermia only on selected patients, such as those with uncomplicated acyanotic congenital heart lesions, a body weight between 10 and 65 kg, and anticipated circulatory arrest time < 60 minutes.…”

“…In stage II, when the esophageal temperature reaches 24°C to 28°C, the actual tympanic temperature drops a further 6°C to 7°C, which provides anti-hypoxic protection of the brain for 60 minutes or more during the circulatory arrest period. 12,13 To prevent cerebral venous congestion, all intravenous fluids were administered through the femoral vein during aortic occlusion. In 4 patients who had circulatory arrest of more than 60 minutes (76 minutes in one case), the cardiac restoration time was quick, and they did not show any neurological deficit postoperatively.…”

“…The general principles of anesthesia and operative technique were not significantly different from those described previously. 12,13 Induction of anesthesia with atropine 0.01 mg·kg −1 , diazepam 0.15 to 0.25 mg·kg −1 , ketamine 5 mg·kg −1 , and pipecuronium 0.08 to 0.1 μg·kg −1 was followed by endotracheal intubation. Anesthesia was maintained with ether and with total muscle relaxation (pipecuronium, 0.06 μg·kg −1 ).…”

“…Our center, established over 40 years ago, continued using this method and developed it further as a safe technique for use in definitive surgery for congenital heart defects. 12,13 This study reviews the outcome of operations during the 5-year period 1995 to 1999, in the light of previous experience.…”