Blood cardioplegia reduces intraoperative ventricular fibrillation and transfusion requirements compared to crystalloid cardioplegia in canine mitral valve repair.

OBJECTIVE: Cardioplegic solutions are indispensable for open-heart surgeries, including mitral valve repair (MVR), a potentially curative treatment for myxomatous mitral valve disease in dogs. However, procedural methodologies are not fully established, and complications are yet to be comprehensively understood. Cardioplegic solutions contain various substances to protect the myocardium under temporal cardiac arrest. Nevertheless, ventricular fibrillation (VF) occurs as a common complication after releasing the crossclamp. Based on these backgrounds, the search for optimal cardioplegic solutions in dogs undergoing MVR is an urgent issue. This study aims to evaluate the occurrence of VF in dogs treated with blood cardioplegia (BCP) versus crystalloid cardioplegia (CCP) during MVR. ANIMALS: A total of 251 client-owned dogs who underwent MVR from November 2015 to November 2017 were included. METHODS: We retrospectively assessed the relationship between VF and type of cardioplegia (CCP or BCP) based on surgical records, including VF incidence, transfusion use, crossclamp time, and echocardiographic measurements. RESULTS: Logistic regression analysis showed that the CCP group was associated with the occurrence of VF (OR, 2.378; CI, 1.133-4.992; P = .022). In addition, the CCP group was associated with transfusion use (OR, 2.586; CI, 1.232-5.428, P = .022). There was no difference between the groups for the pre- and postoperative echocardiographic measurements. CLINICAL RELEVANCE: The BCP group had a lower incidence of VF and less transfusion use than the CCP group. This finding indicates that BCP may be a superior cardioplegic technique for MVR in dogs.

The development of ventricular fibrillation as a complication of pericardiectomy in 16 dogs.

OBJECTIVE: To describe the clinical characteristics, perioperative protocols, and outcomes in dogs diagnosed with ventricular fibrillation (VF) while undergoing pericardiectomy. STUDY DESIGN: Retrospective, multi-institutional study. ANIMALS: Sixteen client-owned dogs. METHODS: Cases were accrued through a listserve request posted to 3 subspecialty veterinary societies. Dogs were included if they developed VF during a pericardiectomy performed through an open or thoracoscopic approach. Data collected included signalment, history and physical examination, surgical approach, histopathology, treatment, and outcome. RESULTS: Indications for pericardiectomy included idiopathic chylothorax (n = 7), neoplasia (4), idiopathic pericardial effusion (4), and foreign body granuloma (1). Surgical approaches included thoracoscopy (12), intercostal thoracotomy (3) and median sternotomy (1). Electrosurgical devices were used to complete at least part of the pericardiectomy in 15 of 16 dogs. Ventricular fibrillation appeared to be initiated during electrosurgical use in 8/15 dogs. However, in 5/15 dogs it was not obviously associated with electrosurgical use. In 3/16 dogs the timing of initiation of VF was unclear. In 7/16 dogs, cardiac arrhythmias were noted prior to the development of VF. Fourteen of 16 dogs died from intraoperative VF. CONCLUSION: In most dogs ventricular fibrillation was a fatal complication of pericardiectomy. Ventricular fibrillation might be associated with the use of electrosurgical devices and cardiac manipulation during pericardiectomy although a causal link could not be established from the data in this study. CLINICAL SIGNIFICANCE: Surgeons must be aware of the risk of VF during pericardial surgery. Electrosurgery might need to be used judiciously during pericardiectomy, particularly in dogs exhibiting cardiac arrythmias.

Closed transventricular dilation of discrete subvalvular aortic stenosis in dogs.

Discrete subvalvular aortic stenosis with peak systolic pressure gradients of more than 60 mm Hg was treated by closed transventricular dilation in six young dogs. Peak systolic pressure gradients were measured by direct catheterization before surgery, immediately after dilation, and 3 months after surgery. Maximum instantaneous pressure gradients were measured by continuous wave Doppler echocardiography before surgery and 6 weeks to 9 months after surgery. All dogs survived the procedure, and two dogs were clinically normal after 9 and 14 months. Two dogs died at week 6 and month 7. One dog was receiving medication for pulmonary edema 15 months after surgery. One dog underwent open resection of the subvalvular ring at month 3, and was clinically normal 6 months after the second procedure. Complications included intraoperative ventricular fibrillation in one dog, and mild postoperative aortic insufficiency in one dog. Closed transventricular dilation resulted in an immediate 83% decrease in the peak systolic pressure gradient from a preoperative mean of 97 +/- 22 mm Hg to a mean of 14 +/- 15 mm Hg. However, systolic pressure gradients measured by direct catheterization at month 3 (77 +/- 26 mm Hg), and by Doppler echocardiography at week 6 to month 9 (85 +/- 32 mm Hg) were not significantly different from preoperative values, which suggested recurrence of the aortic stenosis. Closed transventricular dilation should not be considered a definitive treatment for discrete subvalvular aortic stenosis in dogs, but may be useful in young dogs with critical aortic stenosis as a bridge to more definitive surgery.