Conventional and advanced echocardiographic assessment of systolic function in dogs sedated with dexmedetomidine or acepromazine.

Dexmedetomidine and acepromazine, sedatives commonly used in dogs have opposite vascular effects, resulting in afterload increase and decrease, respectively. This could variably affect systolic myocardial function. Previous echocardiographic studies assessing the cardiovascular effects of these drugs used conventional echocardiography, while advanced techniques such as speckle tracking echocardiography (STE) and tissue Doppler imaging (TDI), which are known to provide a more accurate assessment of systolic function, have been rarely used for this aim. Moreover, in the few studies using advanced techniques, the drugs where combined with opioids. Therefore, the main objective of this prospective study was to assess systolic myocardial function by conventional and advanced echocardiography (STE and TDI), in dogs sedated exclusively with dexmedetomidine or acepromazine not combined with other drugs. Twenty healthy dogs were randomly divided into two groups, Group A (acepromazine, 20 µg/kg IM), and Group D (dexmedetomidine, 5 µg/kg IM), cardiovascular parameters were assessed before sedation (T0), and thirty minutes afterwards (T1). Systolic arterial pressure and heart rate decreased in both groups at T1 as compared to T0. Only one conventional echocardiographic raw variable (left ventricular internal dimension in systole) and three out of five advanced echocardiographic variables (radial TDI systolic velocities at the epicardial region of the left ventricular free wall, longitudinal TDI systolic velocities of the septal mitral valve annulus and the STE-derived left ventricular global strain), were affected in Group D. A systolic impairment was observed in Group D and better estimated by advanced echocardiography. In Group A, only the end diastolic voume index (conventional echocardiography) was decreased. Both protocols seem to induce echocardiographic changes more likely secondary to their vascular action.

Heart rhythm characterization during sudden cardiac death in dogs.

INTRODUCTION/OBJECTIVES: Inherited or acquired arrhythmic disorders and cardiac disease have been associated with sudden cardiac death (SCD) in dogs. The electrical mechanism related to death in most of these cases is unknown. This retrospective study aimed to describe arrhythmic events in dogs that experienced SCD during Holter monitoring. ANIMALS, MATERIALS AND METHODS: Nineteen client-owned dogs that experienced SCD during Holter examination were included. Clinical records from a Holter service database were reviewed, and both the rhythm preceding death and the dominant rhythm causing SCD were analysed. Clinical data, Holter diaries and echocardiographic diagnosis were also evaluated. RESULTS: Structural heart disease was identified in 12/19 dogs (dilated cardiomyopathy in five dogs, arrhythmogenic right ventricular cardiomyopathy in four dogs, myxomatous mitral valve disease in two dogs, and suspected myocarditis in one dog), five of which had concurrent congestive heart failure. Sudden cardiac death was related to ventricular premature complexes or monomorphic ventricular tachycardia degenerating into ventricular fibrillation in 42% of dogs, polymorphic ventricular tachycardia, or torsade de pointes-like inducing ventricular fibrillation in 21%, and asystole or presumptive agonal pulseless electrical activity triggered by malignant bradyarrhythmias in 37%. CONCLUSIONS: The most common rhythm associated with SCD in our population of dogs was ventricular tachycardia leading to ventricular fibrillation, although bradyarrhythmia-related SCD, possibly related to inappropriate vagal reflexes, was also a notable cause.

The variety of phenotypes behind 'double outlet right ventricle': clinical and imaging presentations in four dogs and a cat.

This report describes five cases of double outlet right ventricle (DORV) in four dogs (aged 3-18 months, two males and two females) and a domestic shorthair cat (aged 6 months, female) who presented with various clinical signs including tachypnea (n = 5), exercise intolerance (n = 5), mucous cyanosis (n = 3), delayed growth (n = 2), and/or lethargy (n = 2). The represented canine breeds were poodle, Yorkshire terrier, Samoyed, and Shetland sheepdog. For all animals, echocardiography revealed marked aortic dextroposition with both arterial trunks totally arising from the right ventricle, associated with a ventricular septal defect and various other congenital abnormalities, including subvalvular aortic stenosis (n = 2), minor aortic insufficiency (n = 5), subvalvular pulmonic stenosis with pulmonary trunk hypoplasia (n = 1), patent ductus arteriosus (n = 1), minor mitral and/or tricuspid dysplasia (n = 3). Subsequent cardiac remodeling was characterized by marked right ventricular hypertrophy for all patients, associated with right ventricular and right atrial dilation for most of them (4/5). Two dogs died soon after the initial DORV diagnosis (i.e. after 24 h and two months). A surgical correction attempted for another dog confirmed the presence of a DORV associated with patent ductus arteriosus, but the animal died during the procedure from sudden cardiac arrest. The fourth dog underwent a contrast-enhanced retrospective electrocardiogram-gated multidetector computed tomography angiography under general anesthesia, which confirmed the conotruncal malformation. Despite episodes of exercise intolerance, this dog is still alive, at the age of 53 months, as is the cat at the age of 21 months.

Successful transcatheter pulmonary valve implantation in a dog: first clinical report.

Transcatheter pulmonary valve (TPV) implantation is a therapeutic approach approved by the United States Food and Drug Administration for human patients with failing pulmonary conduits in 2010 and for failing bioprosthetic surgical pulmonary valves in 2017. We report here the first successful transcatheter implantation of a stented valve in a pulmonary position in a dog with congenital pulmonary valve disease. A 3-year-old, 10.9 kg, client-owned Beagle dog was referred for a follow-up visit after a percutaneous balloon valvuloplasty performed 22 months before for treatment of a severe type A valvular pulmonary stenosis. The Doppler-derived peak pressure gradient was 348 mmHg before the procedure and 66 mmHg 24 h after. The dog was lethargic. Echocardiography revealed a mild pulmonary stenosis (pressure gradient-43 mmHg), severe pulmonary regurgitation, and secondary severe right ventricular and right atrial dilation. Worsening of right heart dilation was observed 2 months later despite medical therapy. A TPV implantation was performed using a prestented Melody bovine jugular bioprosthetic valve. The dog recovered uneventfully and was discharged 10 days after the procedure. Right heart dilation resolved within 15 days. The dog was doing well 7 months after valve implantation. This case demonstrates that TPV implantation with a stented valve is technically feasible in dogs with severe pulmonary valve disease. Stringent postoperative care, with particular attention to thrombosis and infectious endocarditis, and appropriate sizing and positioning of the valve stent are keys to the success of this procedure.

Echocardiographic evaluation of the cardiovascular effects of medetomidine, acepromazine and their combination in healthy dogs.

The aim of this study was to compare the cardiovascular effects of medetomidine, acepromazine and their combination administered intravenously in healthy dogs. Ten dogs were included in this study and randomly assigned to the three different sedative protocols: medetomidine (2 µg/kg, protocol M), acepromazine (20 µg/kg, protocol A) and acepromazine followed by medetomidine with the same doses as above (protocol AM), in three different times. In all subjects before (Tbase) and 15 (T15), 50 (T50) and 80 (T80) minutes after the administration of the drugs, the following non-invasive measurements were obtained: blood pressure with oscillometric method, ECG, and echocardiography. Blood pressure and echocardiography evidenced decrease in left ventricular afterload secondary to acepromazine and an increase in right ventricular afterload due to medetomidine. The combination of the two drugs mitigated the effects expected by the single drugs used alone, and prevented the onset of atrioventricular blocks, such as seen in protocol M. The three protocols were eligible for sedation and premedication in healthy dogs. Moreover they had little impact on the echocardiographic variables evaluated in this study.

Intraoperative contrast echocardiography to verify the surgical occlusion of a single extrahepatic portosystemic shunt in a dog.

This report details a bubble echocardiographic study carried out during the surgical treatment of a congenital single extrahepatic portosystemic shunt (PSS) in a Labrador Retriever. After celiotomy, agitated saline was injected through a jejunal vein and microbubbles appeared rapidly in the right cardiac chambers. The test confirmed the presence of a PSS, helping the surgeon to identify the vessel concerned and to rule out a second shunt. Successively, portography confirmed what the exploratory celiotomy had revealed before with the aid of the bubble study: a single shunt was located between the portal vein and the right renal vein. It was completely ligated, as all the criteria for this solution were met. Intraoperative contrast echocardiography (ICE) was easy to perform, helpful and undemanding. It is proposed here as an intraoperative ancillary test to diagnose all PSS and to confirm successful treatment when complete shunt closure is possible.