Surface-induced Deep Hypothermia Research Articles

Short- and long-term results of chordal reconstruction using artificial suture material (polytetrafluoroethylene and polypropylene) in the dog

No previous reports have compared the suitability of expanded polytetrafluoroethylene (ePTFE) and polypropylene as artificial suture materials for chordal reconstruction in mitral valve plasty (MVP) in the dog. Twelve normal dogs were subjected to MVP using surfaceinduced deep hypothermia. In the short-term group (1.5-4 months after surgery), all ePTFE sutures were covered by a tissue sheath including the paired suture arms, which gave the appearance of native chordae from 2 months after surgery. In contrast, all polypropylene sutures were not covered by tissue, and appeared the same as the paired polypropylene suture arms at the operation. In the long-term group (12 months after surgery), all ePTFE sutures were covered by a tissue sheath, which appeared the same as that in the short-term group, and had flexibility without increased thickness with time. In contrast, although the polypropylene suture was covered completely by a tissue sheath in 1 dog, all the other polypropylene sutures were exposed except for both ends of the suture. ePTFE may be superior to polypropylene as an artificial suture material for chordal reconstruction in MVP.

Blood anesthetic levels during surface-induced deep hypothermia under halothane-diethyl ether azeotrope anesthesia.

Blood anesthetic concentration and clinical indicators related to anesthetic management during surface-induced deep hypothermia were determined in seven adult mongrel dogs. The azeotrope of halothane and diethyl ether was assayed by gas chromatography. Blood concentration of halothane ranged from a pre-cooling control of 0.74 vol % to 0.11 vol % at 20 degrees C rewarming; ether ranged from 0.06 vol % at 20 degrees C rewarming to 0.22 vol % at 35 degrees C rewarming. Administration of anesthetic was reduced during cooling because of the spontaneous decrease in mean arterial pressure and heart rate. After elective circulatory arrest was induced, anesthetic was not required until after cardiac resuscitation at about 22 degrees C rewarming. Initial clinical signs indicating a need to increase administration of anesthetic included spontaneous respiration and an increase in mean arterial pressure. Blood azeotrope concentration was significantly lower during rewarming than at comparable temperatures during cooling. We conclude that blood concentration of halothane and ether changes as a function of body temperature and that anesthetic demand may be diminished following total circulatory arrest.

Circulatory Dynamics during Surface-Induced Hypothermia under Halothane-Ether Azeotrope Anesthesia

Circulatory dynamics during surface-induced deep hypothermia using the halothanediethyl ether azeotrope in 100% oxygen (O 2) without circulatory arrest and in 95% O 2 and 5% carbon dioxide (CO 2) with and without 60 minutes of arrest were evaluated in 15 adult mongrel dogs. Mean arterial pressure was lower in animals given 5% CO 2 than in animals given 100% O 2 during cooling. Cardiac output in the 5% CO 2 groups increased until 30°C cooling and then gradually decreased to 29% of control at 20°C. Cardiac output in the 100% O 2 group progressively decreased to 16% of control at 20°C cooling and was 51 to 77% of the output in the 5% CO 2 animals at comparable temperatures throughout the hypothermia procedure. The differences in cardiac output were attributed primarily to changes in stroke volume since heart rates were not significantly different. These changes were probably secondary to differences in systemic vascular resistance, which had increased sixfold in the animals given 100% O 2 and had only doubled in the 5% CO 2 groups at 20°C during cooling. Hemodynamic variables in animals given 5% CO 2 did not reveal significant differences in arrested versus nonarrested animals during early rewarming. However, with further warming, cardiac output, stroke volume, left ventricular stroke work, and mean pulmonary arterial and pulmonary artery wedge pressures were lower, and systemic and pulmonary vascular resistances were higher in the arrest group. We conclude that the improved results with halothane–diethyl ether azeotrope in 95% O 2 and 5% CO 2 during surface hypothermia are due to a greater cardiac output and reduced peripheral vascular resistance.

Changes of kallikrein and serotonin in plasma during and after open-heart surgery.

Plasma kallikrein activity and plasma serotonin were studied during and after open-heart surgery in 15 patients with extracorporeal circulation and in 15 patients with surface-induced deep hypothermia. Following results were obtained: 1) Plasma kallikrein activity which reflects the activation of the kinin system, showed no significant change during extracorporeal circulation, and significantly increased three hours after the termination of perfusion. However, there was no significant difference in plasma kallikrein activity between the patients with and without low cardiac output syndrome (LOS). In surface-induced deep hypothermia, plasma kallikrein activity showed no significant change during and after operation. 2) Plasma serotonin significantly decreased during both extracorporeal circulation and hypothermia. Moreover, there was no significant difference in plasma serotonin between the patients with and without postoperative LOS or pulmonary hypertension. It is assumed that plasma serotonin may not play an important role in regulating blood pressure during or after open-heart surgery with either extracorporeal circulation or surface-induced deep hypothermia.

Pre- and postoperative arrhythmias in congenital heart disease: from the results of surgery using surface-induced deep hypothermia.

The incidence of arrhythmias in 3614 preoperative patients with congenital heart disease was 1.6 per cent. Pre- and postoperative serial ECGs in 186 patients with an isolated VSD and in 58 patients with TOF were reviewed. The incidence of CRBBB and CRBBB-LAH following VSD repair was 33% and 6.6%, respectively, and for TOF was 55% and 5.2%, respectively. Complete A-V block (CAVB) was seen in 2 patients following VSD repair, and none of TOF patients developed CAVB. Late cardiac or dysrrhythmic death was not recognized in our limited follow up period. The indications for surgery in membranous VSD should be determined more carefully, because the risk of the surgical damage to the conduction system is still higher. Moreover, we must keep in mind that damage to the A-V conduction system may occur naturally even in a patient with small VSD. Finally, it can never be overemphasized that physicians must pay attention to the occurrence and course of postoperative arrhythmias.

Enhancement of cooling and rewarming by a jet water system in surface-induced deep hypothermia.

To shorten the time of cooling and rewarming in surface-induced deep hypothermia, we devised a jet water system for hypothermia which was constructed within the water bath of the operating-table. In the clinical applications for open heart surgery under surface-induced deep hypothermia, we found that the time required for cooling and rewarming, particularly the later, was significantly reduced without any adverse effects.

Determination of cardiac output by thermodilution during hypothermia

The thermodilution method for estimating cardiac output was compared with the electromagnetic flowmeter technique in 10 mongrel dogs at normothermia and during surface-induced deep hypothermia. Thermodilution curves obtained during cooling or rewarming must be corrected for the baseline drift caused by changing core temperature. At normothermia, the correlation coefficient between the two methods was 0.96 and the reproducibility of the thermodilution technique was 5 percent. Comparable correlation was present during hypothermia. Curves corrected for baseline drift resulted in significantly different output values from those derived from uncorrected curves (p <0.05). The thermodilution method is valid at low body temperatures. Clinical confirmation of these results, particularly during open heart surgery in infants, is warranted.

主題 I-2 表面冷却超低体温法による1才未満開心術とその問題点

主題 I-2 表面冷却超低体温法による1才未満開心術とその問題点

Platelet kinetics during deep hypothermia

The effects of surface-induced deep hypothermia (20°C) on platelets in terms of their disappearance and location during cooling, recovery with rewarming, and subsequent survival were studied in splenectomized dogs utilizing 51Chromium-tagged autologous platelets. The curves for platelet counts and 51Cr activity were similar with both falling to about 10% of control value at 20°C and both returning to control levels within 1 hr of rewarming. No important differences were observed in the platelet count curves in groups of animals with or without a spleen, with or without 1 2 hr of circulatory arrest, and with or without administration of low molecular weight dextran. The mean platelet survival after hypothermia was somewhat longer (4.9 days) than in normothermic control dogs (4.2 days). The site of hypothermic sequestration was determined by counting 51Cr activity in various organs in animals sacrificed at 20°C; virtually all of the sequestered platelets were found in the liver. This was verified by electron micrographs of the liver. The results indicate that the thrombocytopenia of surface-induced deep hypothermia is due to completely reversible temporary sequestration of platelets in the liver and that the mean survival of platelets exposed to this procedure is not shortened.

Use of athrombogenic tubing for perfusion rewarming following surface-induced deep hypothermia

A method of heparinless, oxygenatorless, left heart bypass perfusion rewarming following surface hypothermia, with the use of a closed circuit with 130 ml. prime volume including heat exchanger, has been devised. The use of polyurethane-polyvinyl-graphite (PPG)-coated tubing has previously been reported. In this text, the use of an athrombogenic coating with cetyl-pyridinium chloride (CPC) as a regional heparin carrier was studied in dogs, comparing groups with PPG tubing and total systemic heparinization or plain polyvinyl tubing without systemic heparinization. Heparin compounded in the CPC coating eluted into the blood and caused mild transient whole-body heparinization during rewarming from 20 degrees to 25 degrees C., as evidenced by prolongation of the thrombin time. Alterations of hematologic parameters in all three groups were similar to those during surface rewarming except for those affected by heparinization. The left heart bypass method was found useful for hypothermic open-heart surgery when utilized with an athrombogenic surface coating or total body heparinization. It was concluded that the CPC coating is superior to the PPG coating since no cracking surface develops, it is translucent, and it provides a more effective athrombogenic surface.

Recent experiences with the Mustard procedure for the complete transposition of the great arteries by means of "bypass hypothermia".

This paper presents our recent results of the Mustard procedure (intra-artrial baffle operation) for the complete transposition of the great arteries performed in 24 infants and children during the past 6 years at the Tohoku University Hospital. All intracardiac repairs were performed using "bypass hypothermia" (surface-induced deep hypothermia, circulatory arrest, and limited cardiopulmonary bypass). The hospital mortality rate was 8% in patients with simple transposition without pulmonary hypertension (Group I, one death in 12 patients), 50% in patients with ventricular septal defect (VSD) and pulmonary hypertension (Group II, 3 deaths in 6 patients), and 20% in patients with VSD and pulmonary stenosis (Group III, one death in 5 patients). Various types of longstanding dysrhythmia were found in 6 out of 18 long-term survivors, and subsequent pace-maker implantation was necessary in one infant. Postoperative pulmonary venous obstruction occurred in 3 infants, and surgical relief of the obstruction was successfully undertaken in 2 of them. Prevention of postoperative dysrhythmia, pulmonary venous obstruction, and possible brain damage are also discussed.

Open-Heart surgery under surface-induced deep hypothermia in infants less than 1 year of age

Open-Heart surgery under surface-induced deep hypothermia in infants less than 1 year of age

Studies on lipid and carbohydrate metabolism during surface-induced deep hypothermia with circulatory arrest for open-heart surgery.

Plasma lipids, blood glucose, plasma insulin (IRI) and serum dopamine-beta-hydroxylase (DBH) were measured in 30 subjects undergoing surface-induced deep hypothermia with circulatory arrest for open-heart surgery. Non-esterified fatty acid (NEFA) in the plasma rapidly increased at the lowest temperature (23 degrees C) reached and other lipids in the plasma decreased during the cooling period. An increase of NEFA and a decrease of triglyceride have been attributed to the action of lipoprotein lipase activity stimulated by heparin. It is also likely that the decrease of other lipids and beta-lipoprotein in the plasma results from the transient hypofunction of the liver due to hypothermia. Blood glucose increased during the cooling period, while plasma insulin showed no significant change. Serum DBH reflecting catecholamine also showed no significant change during the cooling or rewarming periods. Therefore, hyperglycemia in hypothermic open-heart surgery may result from the decrease of peripheral utilization of glucose and from the inhibition of insulin secretion due to the transient pancreatic hypofunction.

Total one-stage repair of interrupted aortic arch associated with aortic septal defect and patent ductus arteriosus

Successful total repair in one stage was performed in a 3-year-old girl who had interrupted aortic arch associated with aortic septal defect and patent ductus arteriosus. Surface-induced deep hypothermia and interrupted perfusion were used. The results of postoperative catheterization and angiocardiographic studies are analyzed, and the literature and results of previous surgical attempts at correction are reviewed.

The role of the liver in the changes of acid-base balance and plasma lipids during surface-induced deep hypothermia.

The role of the liver in the changes of acid-base balance and plasma lipids in surface-induced deep hypothermia for open-heart surgery was investigated clinically and experimentally. The metabolic acidosis generally observed in open-heart surgery under surface-induced deep hypothermia is derived from lactacidemia. Although the accelerated anaerobic glycolysis is partly responsible, the depressed acidic metabolite-disposing ability of the liver also plays an important role. The evidence which is presented to show the decrease of plasma lipids other than NEFA under hypothermia is probably due to the hepatic accumulation of lipids and the decreased lipids release from the liver.

Surgical Correction in Infancy To Reduce Mortality in Transposition of the Great Arteries

The mortality for infants with transposition of the great arteries (TGA) prior to the introduction of medical and surgical septostomy was over 80% by 6 months of age. The mortality has fallen recently, due to balloon atrial septostomy (BAS), but still exceeds 25% by 6 months of age in major centers. The cumulative mortality rises to 40% by 1 year of age with or without additional surgical atrial septectomy. In our center, 12 patients with an average age of 3 months were operated on for interatrial baffle correction of their TGA under surface-induced deep hypothermia. BAS had been done preliminarily in those patients without an adequate atrial communication. Ten of these 12 patients (83%) survived. These patients have been followed up from one month to eight years with an average follow-up of over four years. Surgical correction during infancy offers a better survival rate for infants with TGA than does medical management, with or without palliative surgery.

Electroencephalographic and Neurological Correlates of Deep Hypothermia and Circulatory Arrest in Infants

At present there is much interest in the use of surface-induced deep hypothermia with circulatory arrest in infants undergoing an open-heart procedure for repair of congenital defects. This paper presents our experience with infants who have been monitored by preoperative, intraoperative, and postoperative electroencephalograms as well as by preoperative and postoperative neurological assessments. Our results indicate that young infants tolerate deep hypothermia with circulatory arrest quite well, and we therefore continue to advocate use of this procedure in operations for congenital cardiac disease.

Experimental studies on myocardial metabolism of carbohydrate and lipid in surface-induced deep hypothermia.

In surface-induced deep hypothermia, metabolic acidosis resulting from lactacidemia was observed. In the aspect of myocardial metabolism, the rate of reduction in coronary A-V difference ratio of lactate, pyruvate and NEFA was less than that of coronary flow and myocardial oxygen consumption in the hypothermic heart. Namely, it seems that lactate, pyruvate and NEFA play an important role as energy fuel in the hypothermic heart. On the other hand, myocardial metabolism of glucose was reduced in the hypothermic heart. Moreover, it seems that exogenous corticosteroid and ATP do not influence on the myocardial metabolism of carbohydrate and lipid in the hypothermic heart.

Oxygen Consumption during Surface-Induced Deep Hypothermia under Halothane Anesthesia

The effect of halothane-100% oxygen anesthesia on oxygen consumption was studied in 10 dogs subjected to surface-induced deep hypothermia with 30 minutes of circulatory arrest. The results were compared with previous oxygen consumption data under ether-100% oxygen anesthesia. Low cardiac output, especially during the rewarming period, low Pa02, and a large arteriovenous oxygen difference during rewarming were significantly different in the halothane group, despite identical oxygen consumption in both groups. These differences could not elucidate the exact cause of postoperative motor disturbances associated with 30 minutes of circulatory arrest in the halothane group. The possibility that there was higher oxygen consumption under halothane anesthesia is discussed.

表面冷却低体温下開心術における筋表面 pH の変動について

表面冷却低体温下開心術における筋表面 pH の変動について