Hybrid technique for ventricular septal defect closure in a dog using an Amplatzer® Duct Occluder II.

A left-to-right shunting muscular ventricular septal defect (VSD) was diagnosed in a 4-month-old, female, 1.8 kg Bichon Frise - poodle mix dog. Echocardiographic evidence of cardiac remodeling, calculated pulmonary blood flow (Qp) to systemic blood flow (Qs) ratio of 2.8, and radiographic evidence of pulmonary edema supported the diagnosis of a hemodynamically important VSD. Using a combination of surgery and interventional catheter-based techniques to approach the VSD through the right ventricle, the VSD was occluded with an Amplatzer(®) Duct Occluder (ADO) II device. The ADO II is a low profile, flexible device originally developed for patent ductus arteriosus closure in humans that has been used to close muscular and perimembranous VSD in children. This report describes the hybrid procedure and imaging that was essential for successful occlusion of the VSD in this dog.

An intrapericardial technique for PDA ligation: surgical description and clinical outcome in 35 dogs.

A number of surgical techniques have been reported for dissection and ligation of patent ductus arteriosi (PDAs) in dogs. The objectives of this study were to provide a detailed description of an intrapericardial technique for PDA dissection and ligation and to report the clinical outcome of that technique in dogs. Medical records of 35 dogs were retrospectively reviewed for signalment, clinical signs, echocardiographic findings, surgical time, intra- and postoperative complications, and completeness of ductal closure. Median surgery time was 60 min (range, 35-125 min). Neither intraoperative nor postoperative complications occurred. Within 48 hr of surgery, the continuous left basilar heart murmur was absent in all dogs, and complete echocardiographic closure was confirmed in 29 of 32 dogs. Residual flow was identified echocardiographically in three dogs within 48 hr of surgery. Residual flow was decreased in one dog at 1 mo, which resolved within 33 mo. One dog had mild residual flow postoperatively but did not return for follow-up. The intrapericardial technique was successful for PDA dissection and ligation and had a lower rate (6%) of echocardiographic residual flow compared with previously reported techniques.

Minimally invasive transxiphoid approach to the cardiac apex and caudoventral intrathoracic space.

OBJECTIVE: To describe a minimally invasive surgical technique for procedures involving the caudoventral compartment of the thoracic cavity. STUDY DESIGN: Case series. ANIMALS: Dogs (n = 13). METHODS: Thirteen dogs; undergoing epicardial pacemaker implantation (9), palliative pericardial window (2), perforated right ventricle repair with epicardial pacemaker implantation (1), and peritoneopericardial diaphragmatic hernia (1) were operated by a transxiphoid approach. Dogs were positioned in dorsal recumbency and the bony xiphoid process was dissected free of adjoining tissue and transected proximally and distally. The distal transection was proximal to the cartilaginous junction of the process and the diaphragm. Entry to the thoracic cavity without penetration of the abdomen provided access for surgical treatment. RESULTS: All dogs recovered without complication. No dogs required thoracostomy tube placement. CONCLUSIONS: Transxiphoid approach is minimally invasive and provides adequate exposure for disorders of the caudoventral thoracic cavity.

Pharmacodynamic and efficacy profile of TGN 255, a novel direct thrombin inhibitor, in canine cardiopulmonary bypass and simulated mitral valve repair.

Heparin-induced thrombocytopenia can be a life-threatening sequel to conventional use of unfractionated heparin in cardiopulmonary bypass (CPB). This study evaluated the pharmacokinetic/pharmacodynamic (PK/PD) and efficacy profile of a novel direct thrombin inhibitor, TGN 255, during cardiac surgery in dogs. Point-of-care coagulation monitoring was also compared against the plasma concentrations of TRI 50c, the active metabolite of TGN 255. The study was conducted in three phases using 10 animals: phase 1 was a dose-ranging study in conscious animals (n = 6), phase 2 was a similar but terminal dose-ranging study in dogs undergoing CPB (n = 6), and phase 3 was with animals undergoing simulated mitral valve repair (terminal) using optimal TGN 255 dose regimens derived from phases I and II (n = 4). During the study, PD markers and drug plasma levels were determined. In addition, determinations of hematologic markers and blood loss were undertaken. Phase 1 studies showed that a high-dose regimen of a 5-mg/kg bolus and infusion of 20 mg/kg/h elevated PD markers in conscious animals, at which time there were no measured effects on platelet or red blood cell counts, and the mean plasma concentration of TRI 50C was 20.6 microg/mL. In the phase 2 CPB dose-ranging study, this dosing regimen significantly elevated all the PD markers and produced hemorrhagic and paradoxical thrombogenic effects. In the phase 3 surgical study, a lower TGN 255 dose regimen of a 2.5-mg/kg bolus plus 10 mg/kg/h produced anticoagulation, elevated PD markers, and produced minimal post-operative blood loss in the animals. Plasma levels of TRI 50C trended well with the conventional point-of-care coagulation monitoring. TGN 255 provided effective anticoagulation in a canine CPB procedure, enabling successful completion with minimal blood loss. These findings support further evaluation of TGN 255 as an anticoagulant for CPB.

Surgical correction of subaortic stenosis via right ventriculotomy and septal resection in a dog.

After 2 years of medical management with a beta-adrenoreceptor blocking agent, a 30-month-old castrated male Golden Retriever with subaortic stenosis was treated surgically because of progression of its condition. In an attempt to achieve complete relief of the left ventricular outflow obstruction, a modified Konno procedure consisting of right ventriculotomy and septal myectomy from the infundibular portion of the right ventricle was performed; this combination of procedures allowed wide resection of the septal portion of the left ventricular outflow obstruction. Two years after surgery, the mass of the dog's left ventricle had decreased and the peak calculated pressure gradient across the aortic valve had decreased to 40 mm Hg, compared with a preoperative value of 240 mm Hg; at that evaluation, the dog had gained weight and was able to play normally. It is suggested that use of this modified approach to the outflow tract may have a positive effect on long-term survival time in dogs with subaortic stenosis.

Monolayer-protected gold nanoparticles as a stationary phase for open tubular gas chromatography.

The use of a thin film of monolayer-protected gold nanoparticles (MPNs) as a stationary phase for gas chromatography (GC) is reported. Deposition of a MPN film was obtained in a 2-m, 530-microm-i.d. deactivated silica capillary using gravity to force the solution containing the MPN material through the capillary. By SEM analysis, the average film thickness was determined to be 60.7 nm. The retention behavior for the dodecanethiol MPN column was studied using four compound classes (alkanes, alcohols, aromatics, ketones), and retention orders were objectively compared to a commercially available column (AT-1, 100-nm film thickness). Separation of an eight-component mixture was performed using both isothermal and temperature-programming methods with the dodecanethiol MPN phase and compared to an isothermal separation with the AT-1 phase. The AT-1 phase separation had an efficiency, N, of 6200 (k' = 0.33) while the dodecanethiol MPN phase separation had an efficiency, N, of 5700 (k' = 0.21) for the same analyte, octane. The reduced plate height, h, for octane was found to be less than 1 at the optimum linear flow velocity, indicating the MPN column operated near the optimum possible performance level. Robustness of the MPN phase is also discussed with consistent performance observed over several months. Overall, MPNs appear promising as a stationary-phase material for GC and as an experimental platform to study their thermodynamic and mass-transfer properties.

Predicting acute renal failure after cardiac surgery: validation and re-definition of a risk-stratification algorithm.

BACKGROUND: Acute renal failure (ARF) after cardiac surgery is associated with significant morbidity and mortality, irrespective of the need for dialysis. Previous studies have attempted to identify predictors of ARF and develop risk stratification algorithms. This study aims to validate the algorithm in an independent cohort of patients that includes a significant proportion of female and black patients and compares two different definitions of renal outcome. METHODS: A large single center cardiac surgery database was examined (n, 24,660; 1993-2000) which included 29.9% females and 3.7% black patients. Post-operative ARF was defined as: a) ARF requiring dialysis, b) > 50% reduction in creatinine clearance relative to baseline or requiring dialysis. Clinical variables related to baseline renal function and cardiovascular disease were used in recursive partitioning analysis for both outcome definitions. Chi-square goodness of fit analysis was performed to validate the algorithm. RESULTS: The frequency of post-operative ARF requiring dialysis ranged between 0.5 and 15.5% based on the risk categories with the area under the receiver operating characteristic (ROC) curve of 0.78. Using the more inclusive definition of ARF, the frequency was significantly higher ranging from 2.6 to 25%(P < 0.001) with an area under ROC curve of 0.65. CONCLUSIONS: The renal risk stratification algorithm is valid in predicting post-operative ARF in an independent cohort of patients, well represented by differences in gender and race. Since the need for dialysis remains subjective, a more objective and inclusive definition of ARF may help in identifying a larger number of patients 'at-risk'.