A Comparative Study between Hypothermic and Normothermic Cardiopulmonary Bypass in Open Heart Surgery in Dogs. Effects on Systemic Hemodynamics.

Abstract

ABSTRACT. Open heart surgery was performed on two groups of dogs under extracorporeal circulation with or without hypothermia to investigate hemodynamic changes during extracorporeal circulation. During hypothermic cardiopulmonary bypass (CPB), arterial O 2 tension and postoperative blood pressure were favorably maintained, indicating that hypothermic extracorporeal circulation can be performed for a long period of time. On the other hand, during normothermic CPB, the average surgical duration was significantly shorter, and marked shifts in the concentrations of various enzymes were suppressed. However, due to reductions in arterial O 2 tension, the length of cardiac arrest time was restricted, demonstrating that this method is suitable for performing extracorporeal circulation for CPB of relatively short duration. If circulation circuitry can be improved, such as through the development of a surpassing oxygenator, normothermic CPB would incur less stress on the body, thus making it preferential to hypothermic CPB in most cases.-KEY WORDS: canine, extracorporeal circulation, hypothermia, normothermia.J. Vet. Med. Sci. 61(4): 331-336, 1999 normothermic CPB in humans have yet to be fully clarified. The present study investigate the effect of extracorporeal circulation using an artificial heart-lung machine with or without hypothermia on pathophysiology of dogs (in particular, hemodynamics). MATERIALS AND METHODS Animals:Fourteen clinically healthy male beagles were examined. All dogs were cared for in accordance with the experimental animal guidelines of Tokyo University of Agriculture and Technology. The animals were randomly divided into two groups. Group H (hypothermic CPB, age 2.2 ± 1.2 years (mean ± standard error), weight 10.0 ± 0.8 kg, n=7), in which their body temperature was reduced to 24-26°C, and Group N (normothermic CPB, age 2.0 ± 0.4 years, weight 10.4 ± 0.3kg, n=7), in which their body temperature was maintained at 36°C. To obtain clinically useful data, open heart surgery was performed assuming that the dogs would live for at least one month after surgery.Surgical technique and cardiopulmonary bypass system: Dilation and remodeling of the right ventricular outflow tract of all dogs was performed using a patch graft technique as if they had pulmonary stenosis. The artificial heart-lung machine (NAPS-III, Fig. 1) [18,19,21] that was used in the present study consists of three two-roller pumps, a membrane oxygenator, a heat exchanger, and a circuit. Before starting extracorporeal circulation, the machine was primed with lactated Ringer solution, 5% glucose, 7% sodium bicarbonate, and 20% mannitol, without using whole blood. The dogs were pretreated with atropine sulfate (0.04 mg/kg) and acepromazine maleate (0.4 mg/kg), and whenCurrent techniques in open heart surgery in humans involve establishing extracorporeal circulation using an artificial heart-lung machine. In this method, the artificial heart-lung machine performs systemic respiration and circulation so that the heart can be temporarily sto...

Efficacy of open patch‐grafting under cardiopulmonary bypass for pulmonic stenosis in small dogs

“…CPB 16,18–22 enables the maintenance of cardiac arrest for more than 60 mins, with satisfactory recovery in healthy Beagle dogs. In Japan, PS is often diagnosed in toy dogs such as the Pomeranian and Shih Tzu, and we have developed an artificial heart–lung machine especially for dogs of this size.…”

A Long Term Comparison between Denacol EX-313-Treated Bovine Jugular Vein Graft and Ultrafine Polyester Fiber Graft for Reconstruction of Right Ventricular Outflow Tract in Dogs.

“…Operative technique: Reconstruction of the right ventricular outflow tract using a patch graft was performed in the two groups of dogs employing an extracorporeal circulation system with an artificial heart-lung machine [12,13]. The Denacol grafts and the UFPF (Toray Graft, Toray Co., Tokyo, Japan) grafts with a thickness of 0.5 mm were trimmed to produce a patch with a length of 40 mm and a width of 20 mm.…”

Comparison of Extracapillary and Endocapillary Blood Flow Oxygenators for Open Heart Surgery in Dogs: Efficiency of Gas Exchange and Platelet Conservation.

“…The myocardium was protected by antegrade injection of cold cardioplegia solution, and the surface of the heart was cooled regionally using ice slush. Dilation and remodeling of the right ventricular outflow tract in all dogs was performed using a patch graft technique to simulate pulmonary stenosis [10,17]. After completing the necessary procedures, switching back to partial extracorporeal circulation, the heart was massaged manually, and cardiac activity was reinitiated using a defibrillator.…”

“…However, this oxygenator can cause blood cell destruction because of high pressure gradients across the apparatus [2,6,17].…”