Janice M. Bright

Association of Age and Heart Rate with Pulsed-Wave Doppler Measurements in Healthy, Nonsedated Cats

BACKGROUND Associations of age and heart rate with blood flow velocities and durations assessed by pulsed-wave (PW) Doppler echocardiography in cats are incompletely understood. OBJECTIVES To determine the effects of age and heart rate on blood flow velocities and durations of cardiac events obtained by PW Doppler echocardiography in healthy, nonsedated cats. ANIMALS A convenience sample of 87 healthy, nonsedated cats aged 3 months to 19 years. METHODS Prospective, observational study. PW Doppler measurements were obtained by echocardiography. Association of age and heart rate with PW Doppler values was evaluated by simple and multiple linear regressions and ANCOVA. RESULTS Significant weak positive relationships were found between age and isovolumic relaxation time (IVRT) (R2= 0.18; P< or = .001), and between age and duration of pulmonary venous retrograde flow (R2= 0.07; P= .041). There was a significant weak negative relationship between age and transmitral peak early diastolic velocity (R2= 0.19; P< or = .001). Age and heart rate were significantly related to pulmonary venous peak systolic velocity (R2= 0.13; P= .008). Heart rate affected transmitral peak late diastolic velocity (R2= 0.11; P= .006). After adjusting for heart rate effect, the PW Doppler variables that were significantly different between age groups were transmitral peak early diastolic velocity (P< or = .001), duration of transmitral late diastolic flow (P< or = .001), IVRT (P< or = .001), and the ratio of duration of transmitral late diastolic flow to duration of pulmonary venous retrograde flow (P= .029). CONCLUSIONS AND CLINICAL IMPORTANCE The association of several PW Doppler-derived variables and age and heart rate is weak and not clinically important.

Echocardiographic Evidence of Left Ventricular Hypertrophy in Obese Dogs

BACKGROUND Cardiomyopathy of obesity occurs in humans, but the gross and cellular myocardial response to obesity in dogs is not well defined. OBJECTIVES To characterize in vivo myocardial morphology and function in normotensive obese dogs, and quantitate collagen, triglyceride and myocyte cross-sectional area (CSA) in postmortem tissues from obese dogs. ANIMALS Echocardiographic-Doppler measurements of normotensive obese dogs (n = 19) without historical or physical examination evidence of disease, and lean healthy dogs (n = 19) matched for age and ideal weight. Postmortem data were obtained from a separate population of 4 obese and 12 lean dogs without evidence of cardiac disease. METHODS A prospective, observational study of myocardial morphology and function was conducted by echocardiographic-Doppler measurement. Left ventricular (LV) tissue was collected for quantitation of triglyceride, collagen, and myocyte CSA. RESULTS Compared with lean control dogs, obese dogs had increased systolic blood pressure (obese 153 ± 19 mm Hg; lean 133 ± 20 mm Hg; P = .003), and increased LV free wall thickness at end-diastole (obese 9.9 ± 1.8 mm, lean 8.7 ± 1.5 mm; P = .03) and end-systole (obese 15.2 ± 2.3 mm, lean 12.9 ± 2.3 mm; P = .004). Isovolumic relaxation time was prolonged in 7/19 (37%) of obese dogs, compared with normal ranges. Myocardial triglyceride and collagen content and myocyte CSA were similar between groups. CONCLUSIONS AND CLINICAL IMPORTANCE As in humans, LV hypertrophy and diastolic dysfunction can be an early myocardial change in some obese dogs.

A retrospective evaluation of transthoracic biphasic electrical cardioversion for atrial fibrillation in dogs

OBJECTIVES To evaluate safety, efficacy, and clinical usefulness of biphasic transthoracic cardioversion for management of dogs with atrial fibrillation (AF). BACKGROUND In dogs AF is usually managed with heart rate control rather than by restoration of sinus rhythm (SR). However, restoration of SR has potential advantages of improving cardiac output and reducing ventricular filling pressures, and biphasic cardioversion provides an improved benefit/risk ratio compared to traditional monophasic cardioversion. ANIMALS, MATERIALS AND METHODS Retrospective analysis of data from 39 dogs with spontaneous AF managed with biphasic transthoracic cardioversion was done. Conversion characteristics, adverse effects, and duration of SR were evaluated. Effects of heart disease and pretreatment with amiodarone on success of cardioversion and on duration of SR were also evaluated. RESULTS Restoration of SR was achieved in 36 of 39 dogs (92.3%). Presence of heart disease or atrial enlargement had no effect on cardioversion characteristics or ability to restore SR. Median duration of SR following cardioversion and treatment with amiodarone was 120 days. Dogs with lone AF remained in SR longer than those with heart disease. CONCLUSIONS Biphasic cardioversion is safe and effective. Although duration of SR varied, a majority of dogs remained in SR long enough to benefit.

Transcatheter intravascular stent placement to relieve supravalvular pulmonic stenosis.

Valvular pulmonic stenosis has been successfully treated in dogs via minimally invasive transcatheter balloon dilation procedures for almost 20years. Supravalvular pulmonic stenosis however is not amenable to balloon dilation procedures. Although several surgical procedures are described for treatment of pulmonic stenosis, the morbidity and mortality of these procedures are significantly higher than for transcatheter approaches. Two cases of supravalvular pulmonic stenosis are presented, one acquired and one congenital, which were successfully treated with transcatheter intravascular stent placement. The procedure alleviated the stenotic lesion and resolved clinical signs.

Echocardiographic Findings in 11 Cats with Acromegaly

Background Information regarding cardiac changes in domestic cats with acromegaly is limited. Hypothesis/Objectives The objective of this study was to describe the echocardiographic findings in cats with acromegaly. Animals Eighteen cats diagnosed with acromegaly at Colorado State University between 2008 and 2012. Of these 18 cats, 11 had echocardiography performed. Methods A retrospective review of medical records was made to identify cats with acromegaly that also had echocardiography performed. Results Of the 11 cats identified, 7 had left ventricular concentric hypertrophy, 6 had left atrial enlargement, and 7 had evidence of abnormal diastolic function. All 11 cats had evidence of structural or functional cardiac disease. Conclusions and Clinical Importance Cardiovascular abnormalities frequently are present in cats with acromegaly, and a complete cardiac evaluation should be considered in these patients.

Transvenous occlusion of patent ductus arteriosus in 56 consecutive dogs.

OBJECTIVE Document safety and efficacy of transvenous catheter occlusion of patent ductus arteriosus (PDA) over a wide range of ductal and patient sizes. ANIMALS, MATERIALS AND METHODS Retrospective study of fifty-six consecutive dogs referred to Colorado State University with diagnosis of PDA. All cases utilized the transvenous approach, via the femoral vein. Occlusion was achieved using a coil (Flipper) in dogs with PDA minimal dimension of <or=4 mm. Amplatzer duct occluder or Amplatzer vascular plugs were used in dogs with PDA minimal dimension >4 mm, or if a coil was unstable following deployment. RESULTS Ductal occlusion was achieved using the transvenous route alone in 54/56 dogs (96.4%). Occlusion was achieved using detachable Flipper coils in 39/42 dogs (92.9%) in which coil occlusion was attempted, with 38/39 dogs (97.4%) requiring only a single coil. In 16 dogs, occlusion was achieved using an Amplatzer duct occluder or vascular plug. Post-procedure residual ductal flow was absent or only mild in 36/39 (92.3%) dogs in which it was assessed. Procedural mortality rate was 1.7%, and major complication rate 7.0%. CONCLUSION Transcatheter occlusion via a transvenous approach is a safe and effective method for treating PDA in dogs and is useful for small dogs (<2.5 kg).

Chronicity of Atrial Fibrillation Affects Duration of Sinus Rhythm after Transthoracic Cardioversion of Dogs with Naturally Occurring Atrial Fibrillation

BACKGROUND Atrial fibrillation (AF) in dogs can be managed by electrical cardioversion to sinus rhythm, but early recurrence of AF occurs in some dogs. In humans, the commonly evaluated clinical variables for prediction of early relapse of AF are left atrial size and duration of AF. It is unclear whether the duration of AF affects maintenance of sinus rhythm after cardioversion in dogs with spontaneous AF. HYPOTHESIS That duration of sinus rhythm after cardioversion is related to the chronicity of AF. ANIMALS Forty-one consecutive dogs that had undergone successful transthoracic cardioversion for spontaneous AF were evaluated. METHODS The relationship between the duration of documented AF and the duration of sinus rhythm after cardioversion was statistically evaluated using data obtained retrospectively. The effects of structural heart disease and pretreatment with amiodarone were also evaluated. RESULTS The presence of structural heart disease and the duration of documented AF had significant effects on maintenance of sinus rhythm after cardioversion (P <.001 and P=.022, respectively). The duration of documented AF was inversely related to the duration of sinus rhythm (P=.022) in dogs with and without structural heart disease. CONCLUSIONS AND CLINICAL IMPORTANCE Estimates of duration of sinus rhythm based on the duration of documented AF are provided for dogs with and without heart disease allowing prediction of risk for early AF relapse.

Thrombotic complications associated with atrial fibrillation in three dogs.

Atrial fibrillation (AF) is the most common chronic pathologic arrhythmia in dogs, and whereas thromboembolism is a common complication of AF in humans, this complication has not been previously reported in dogs. This report describes thrombotic complications associated with AF in three dogs. A spherical left atrial mass consistent with a thrombus was identified in two dogs during echocardiographic examination. A third dog experienced arterial thromboembolism confirmed with ultrasound and postmortem examination. These cases provide a unique antemortem description of intra-atrial thrombus formation and cardioembolic disease associated with AF in dogs, and raise awareness of the importance of thorough echocardiographic evaluation of the atria for thrombus prior to pharmacologic cardioversion or direct current cardioversion.

Chronic cardiac tamponade in a cat caused by an intrapericardial biliary cyst

A 1-year-old domestic longhair cat presented to our hospital with a 4-month history of progressive exercise intolerance and coughing. Two-dimensional echocardiography confirmed the presence of an intrapericardial cyst and cardiac tamponade. Tamponade was relieved via percutaneous aspiration of the cyst. The cyst was surgically excised 4 days later, and histopathology was consistent with a biliary cyst. The cats clinical signs completely resolved following surgery.

Pulmonary artery dissection in eight dogs with patent ductus arteriosus

OBJECTIVES To describe a series of dogs with pulmonary artery dissection and patent ductus arteriosus (PDA). ANIMALS Eight dogs. METHODS Retrospective case series. RESULTS Pulmonary artery dissection was diagnosed in 8 dogs, 3 were Weimaraners. Four dogs presented in left-sided congestive heart failure, 4 presented for murmur evaluation and without clinical signs, and 1 presented in right-sided congestive heart failure. In 7 dogs the dissection was first documented concurrent with a diagnosis of uncorrected PDA. In the other dog, with pulmonary valve stenosis and PDA, the dissection was observed on autopsy examination 17 months after balloon pulmonary valvuloplasty and ductal closure. Median age at presentation for the 7 dogs with antemortem diagnosis of pulmonary artery dissection was 3.5 years (range, 1.5-4 years). Three dogs had the PDA surgically ligated, 2 dogs did not undergo PDA closure, 1 dog failed transcatheter occlusion of the PDA with subsequent surgical ligation, 1 dog underwent successful transcatheter device occlusion of the PDA, and 1 dog had the PDA closed by transcatheter coil delivery 17 months prior to the diagnosis of pulmonary artery dissection. The 2 dogs that did not have the PDA closed died 1 and 3 years after diagnosis due to heart failure. CONCLUSIONS Pulmonary artery dissection is a potential complication of PDA in dogs, the Weimaraner breed may be at increased risk, presentation is often in mature dogs, and closure of the PDA can be performed and appears to improve outcome.