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. Cardiopulmonary bypass was provided by a heart-lung machine h with an extracorporeal circuit, 0.5-m 2 oxygenator, and heat exchanger. i The CPB circuit was filled with 20% D-mannitol j (5 mL/kg), 7% sodium bicarbonate k (2 mL/kg [0.9 mL/lb]), heparin sodium l

Full access
in Journal of the American Veterinary Medical Association

SUMMARY

We investigated the relation between left ventricular dysfunction and myocardial edema in dogs with heartworm (Dirofilaria immitis) infection that were undergoing cardiopulmonary bypass. Dogs with and without D immitis were anesthetized by continuous thiopental infusion and were mechanically ventilated. Sonomicrometry crystals were placed on the long and short axes of the left ventricle, and a Millar pressure transducer was placed in the left ventricular chamber. Pressure-volume loops were digitized and continuously recorded. Dogs with and without D immitis were placed on standard hypothermic cardiopulmonary bypass, with 1 hour of aortic cross-clamp. Wet-to-dry weight ratio corrected for residual blood volume was used to quantitate the volume of myocardial edema. Preload recruitable stroke work was used as a preload-independent index of systolic function. Tau, the isovolumic relaxation time constant, was determined to assess diastolic relaxation. Dogs with D immitis had increased baseline myocardial wet-to-dry weight ratio. After cardiopulmonary bypass, myocardial edema increased in all dogs. Acute edema attributable to cardiopulmonary bypass decreased preload recruitable stroke work in all dogs of both groups, and dogs with D immitis could not be weaned from cardiopulmonary bypass. Myocardial edema increased diastolic relaxation times (τ) in dogs with and without D immitis. We conclude that cardiopulmonary bypass and heartworm infection induce myocardial edema. This edema compromises left ventricular systolic and diastolic function making D immitis an important confounding factor in weaning dogs from cardiopulmonary bypass.

Free access
in American Journal of Veterinary Research

chordae tendinae using Gore-Tex suture material and is performed under cardiopulmonary bypass. The aim is to substantially reduce the amount of mitral regurgitation, which, if successful, allows discontinuation of preoperative diuretic therapy, resolution

Free access
in Journal of the American Veterinary Medical Association

arrest while maintaining the flow of oxygenated blood to other organs via cardiopulmonary bypass. 5 , 6 This involves halting the heart’s electromechanical activity using a cold, potassium-rich cardioplegic solution, protecting the myocardium from

Open access
in American Journal of Veterinary Research

. Figure 3— Intraoperative photograph of the modified thoracic catheter secured in the right atrium. Following unsuccessful transcatheter closure, an open heart patch repair under cardiopulmonary bypass was discussed with and declined by the owner

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine effects of reducing the diameter of the left ventricle of dogs by plication of the left ventricular free wall.

Animals—8 healthy adult mixed-breed dogs.

Procedure—Left lateral thoracotomy and a T-shaped pericardiotomy were performed. The free wall of the left ventricle was imbricated with 3 interrupted transfixing sutures applied in a horizontal mattress pattern, using 3-0 polypropylene suture assembled on a straight cutting needle. Surgeons were careful to avoid the coronary vessels. Echocardiography was performed 24 hours before and 48 hours after surgery. Electrocardiography was performed before and 1, 2, 7, 15, 21, 30, and 60 days after surgery.

Results—Echocardiographic measurements revealed that the diameter of the left ventricle was reduced by a mean of 23.5%. Electrocardiography revealed ventricular premature complexes 24 hours after surgery that regressed without treatment during the first week after surgery.

Conclusions and Clinical Relevance—Plication of the left ventricular free wall of dogs can reduce enddiastolic and end-systolic dimensions of the left ventricle. The technique is simple and does not require cardiopulmonary bypass. According to Laplace's law, the reduction of cardiac diameter leads to reduction on free-wall tension and may improve left ventricular function in dilatated hearts. Thus, additional studies involving dogs with dilated cardiomyopathy should be conducted. (Am J Vet Res 2001;62:297–300)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare outcome and intermediateterm survival for dogs undergoing open surgical correction of subvalvular aortic stenosis (SAS) with those for dogs with SAS that did not undergo surgery.

Design—Retrospective study.

Animals—44 dogs with congenital SAS.

Procedure—Maximum instantaneous systolic pressure gradients were determined by use of Doppler echocardiography. Cardiopulmonary bypass and open surgical correction of SAS (membranectomy with or without septal myectomy) was performed in 22 dogs, whereas 22 dogs did not undergo surgical correction. Cumulative survival was compared between surgical and nonsurgical groups, using Kaplan-Meier nonparametric analysis and a Mantel-Cox log-rank test.

Results—Initial systolic pressure gradients were not significantly different for dogs undergoing surgery (128 ± 55 mm Hg), compared with those that did not undergo surgery (117 ± 57 mm Hg). Systolic pressure gradients were significantly decreased after surgery in dogs that underwent surgery (54 ± 27 mm Hg). Cumulative survival was not significantly different between dogs in the surgical and nonsurgical groups. Censoring surgery-related mortality in the analysis still did not reveal a significant difference in cumulative survival between the surgical and nonsurgical groups.

Conclusion and Clinical Relevance—Despite reductions in the systolic pressure gradient and possible associated improvement in exercise tolerance, a palliative benefit on survival was not documented in dogs undergoing surgery for SAS. (J Am Vet Med Assoc 2000;216:364–367)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate plication of the free wall of the left ventricle, which reduces the left ventricular area and volume, as a method to improve the left ventricular systolic function without cardiopulmonary bypass.

Animals—8 mixed-breed adult dogs.

Procedure—Dilated cardiomyopathy (DCM) was induced in each dog by administration of doxorubicin (30 mg/m2, IV, q 21 d for 168 days). Two dogs died during induction of cardiomyopathy. Plication surgery was performed in 4 dogs. Two dogs did not ondergo to surgery (control group). Values for cardiac output (CO), 2-dimensional and M-mode echocardiography, arterial blood pressure, electrocardiography, blood cell counts, and serum biochemical analyses were recorded after induction of DCM (baseline) and 1, 2, 7, 15, 21, 30, 60, 90, 120, 150, and 180 days after plication surgery. Ambulatory ECG (Holter) recordings were conducted for 24 hours on the day of surgery.

Results—1 dog died after plication surgery. The remaining dogs undergoing ventricular plication had a significant improvement in CO, ejection fraction, and fractional shortening and reductions of left ventricular area and volume after surgery. Electrocardiographic and Holter recordings revealed premature ventricular complexes, which resolved without treatment during the first week after surgery. Clinical condition of the control dogs declined, and these 2 dogs died approximately 40 days after induction of cardiomyopathy.

Conclusions and Clinical Relevance—Plication of the free wall of the left ventricle improved left ventricular systolic function in dogs with doxorubicininduced cardiomyopathy. Additional studies are needed to evaluate its application in dogs with naturally developing DCM. (Am J Vet Res 2005;66:238–243)

Full access
in American Journal of Veterinary Research

Objective

To describe the surgical technique for open resection of congenital subvalvular aortic stenosis in dogs and to determine outcome of dogs undergoing the procedure.

Design

Uncontrolled clinical trial.

Animals

17 dogs with congenital discrete subvalvular aortic stenosis.

Procedure

Dogs were placed on cardiopulmonary bypass by catheterizing the femoral artery and both vena cavae. The aorta was cross clamped, and cold cardioplegia solution was administered. The aortic root then was opened with a curvilinear incision. A subvalvular discrete fibrous ring was resected in all dogs. Septal myectomy was performed simultaneously on 11 dogs.

Results

15 of 17 dogs survived the operation and were discharged from the hospital. Mean ± SD maximal instantaneous aortic systolic pressure gradient measured by means of Doppler echocardiography was significantly reduced from 119 ± 42 mm of Hg before surgery to 41 ± 10 mm of Hg 12 months after surgery. Despite substantial reduction in the systolic pressure gradient, 4 of 15 dogs died suddenly between 7 days and 30 months after surgery. Three of the 4 dogs that died suddenly had pressure gradients ≥ 180 mm of Hg and ventricular tachycardia before surgery. Eleven dogs were still alive between 1 and 48 months after surgery.

Clinical Implications

The procedure resulted in substantial reductions in systolic pressure gradients in dogs with severe congenital subvalvular aortic stenosis. However, some dogs with severe aortic stenosis died suddenly after surgery. Thus, this surgery should not be considered curative. Proof of a survival benefit in dogs undergoing this surgery will have to await longer term follow-up. (J Am Vet Med Assoc 1996;209:1255–1261)

Free access
in Journal of the American Veterinary Medical Association

administration (eg, during cardiopulmonary bypass procedures, 3,4 prior to surgical intervention to treat subarachnoid hemorrhage, 5 following dental extraction in hemophiliac patients, 6 during extracorporeal membrane oxygenation in neonatal cardiac surgery

Full access
in American Journal of Veterinary Research