Etienne Côté

Ventricular Tachyarrhythmias in 106 Cats: Associated Structural Cardiac Disorders

BACKGROUND Ventricular tachyarrhythmias occur in association with cardiac and extracardiac disorders in many species of animals, but information identifying concurrent disorders in cats with such arrhythmias is scarce. METHODS We investigated coexisting diseases by retrospectively evaluating medical records of cats with ventricular tachyarrhythmias seen during a 51-month period at 1 institution. For comparative purposes, we evaluated records of dogs with similar arrhythmias during the same time period. All cats and dogs had premature ventricular complexes, accelerated idioventricular rhythm, ventricular tachycardia, or some combination of these arrhythmias, and all had undergone echocardiography during the same visit that led to the diagnosis of ventricular tachyarrhythmia. RESULTS AND CONCLUSIONS Most (102/106; 96%) cats had at least 1 echocardiographically apparent abnormality concurrent with ventricular tachyarrhythmias. Ventricular tachyarrhythmias in cats were most commonly associated with myocardial disease (eg, left ventricular concentric hypertrophy [n = 66], restrictive or unclassified cardiomyopathy [n = 17], and dilated cardiomyopathy [n = 6]). When comparing dogs and cats that had ventricular tachyarrhythmias and were diagnosed on the same clinical service of the same institution, an echocardiographically apparent cardiac lesion was seen more often in cats (102/106, 96%) than in dogs (95/138, 69%) (P < .001).

Wide-complex tachycardia associated with severe hyperkalemia in three cats

The well recognized cardiac effects of severe hyperkalemia include progressive rhythm and conduction disturbances such as bradycardia, spiked and narrow T waves, widening QRS complex, widening and flattening P wave, disappearance of the P wave, and cardiac arrest. Paradoxically, a heart rate greater than 200 beats/min may coexist with hyperkalemia in some cats. This report describes three cats with moderate to severe hyperkalemia and concurrent rapid heart rate. In each cat, the serum potassium (K+) concentration was ≥7.5 mEq/dl with a concurrent heart rate>200 beats/min. In each cat, nine-lead electrocardiograms demonstrate an absence of P waves and a wide-complex tachycardia. Hyperkalemia should be considered in the differential diagnosis when a feline electrocardiogram demonstrates a wide-complex tachycardia without identifiable P waves.

Management of incidentally detected heart murmurs in dogs and cats.

A dog or a cat has an incidentally detected heart murmur if the murmur is an unexpected discovery during a veterinary consultation that was not initially focused on the cardiovascular system. This document presents approaches for managing dogs and cats that have incidentally-detected heart murmurs, with an emphasis on murmur characteristics, signalment profiling, and multifactorial decision-making to choose an optimal course for a given patient.

Evaluation of platelet function in dogs with cardiac disease using the PFA-100 platelet function analyzer

BACKGROUND Cardiac disease has the potential to alter platelet function in dogs. Evaluation of platelet function using the PFA-100 analyzer in dogs of multiple breeds and with a broad range of cardiac conditions would help clarify the effect of cardiac disease on platelets. OBJECTIVES The objective of this study was to assess differences in closure time (CT) in dogs with cardiac disease associated with murmurs, when compared with that of healthy dogs. METHODS Thirty-nine dogs with cardiac murmurs and turbulent blood flow as determined echocardiographically were included in the study. The dogs represented 23 different breeds. Dogs with murmurs were further divided into those with atrioventricular valvular insufficiency (n=23) and subaortic stenosis (n=9). Fifty-eight clinically healthy dogs were used as controls. CTs were determined in duplicate on a PFA-100 analyzer using collagen/ADP cartridges. RESULTS Compared with CTs in the control group (mean+/-SD, 57.6+/-5.9 seconds; median, 56.5 seconds; reference interval, 48.0-77.0 seconds), dogs with valvular insufficiency (mean+/-SD, 81.9+/-26.3 seconds; median, 78.0 seconds; range, 52.5-187 seconds), subaortic stenosis (71.4+/-16.5 seconds; median, 66.0 seconds; range, 51.5-95.0 seconds), and all dogs with murmurs combined (79.6+/-24.1 seconds; median, 74.0 seconds; range, 48.0-187 seconds) had significantly prolonged CTs (P<.01). CONCLUSIONS The PFA-100 analyzer is useful in detecting platelet function defects in dogs with cardiac murmurs, most notably those caused by mitral and/or tricuspid valvular insufficiency or subaortic stenosis. The form of turbulent blood flow does not appear to be an important factor in platelet hypofunction in these forms of cardiac disease.

Cardiogenic Shock and Cardiac Arrest

Severe heart disease may cause hypotension and hypoperfusion, and ultimately circulation may cease altogether. These two clinical syndromes are cardiogenic shock and cardiac arrest, respectively. This review summarizes the causes and clinical features of each, and describes the treatment options available to clinicians managing patients in cardiogenic shock.

THE EFFECT OF DEXMEDETOMIDINE ON RADIOGRAPHIC CARDIAC SILHOUETTE SIZE IN HEALTHY CATS

Dexmedetomidine, an alpha2 -adrenergic agonist, may be used in companion animals for chemical restraint, including cardiac evaluation. Echocardiographic changes associated with alpha2 -adrenergic agonists have been described; however reports of radiographic changes in cats were not found at the time of this study. Aims of this observational, prospective, experimental study were to describe the effects of dexmedetomidine on the radiographic appearance of the cardiac silhouette in healthy, adult cats. Fourteen healthy adult cats received dexmedetomidine 40 mcg/kg IM. Right lateral, left lateral, ventrodorsal, and dorsoventral thoracic radiographs were obtained for each cat at three time points: presedation, intrasedation, and postsedation (≥ two hours after reversal with atipamezole). Radiographs were evaluated in a blinded, randomized fashion by two independent observers using the vertebral heart score on all four views, the number of intercostal spaces on lateral projections, and the percent width of thorax on ventrodorsal and dorsoventral projections. Median vertebral heart score on right lateral view was significantly increased intrasedation (median = 7.8; range = 7.25-8.25) compared to presedation (median = 7.5; range = 7-8 [P = 0.001]). Median percentage width was significantly higher intrasedation (70% on VD; range 65-80 [P = 0.001], and 75% on DV; range 65-80 [P = 0.006]) compared to presedation (65%; range 65-75 on both projections). Dexmedetomidine was associated with a small but significant increase in cardiac silhouette size on right lateral (vertebral heart score), ventrodorsal (percentage width), and dorsoventral (percentage width) radiographs in healthy adult cats. This effect should be taken into consideration for future interpretation of thoracic radiographs in dexmedetomidine-sedated cats.

Comparison of peak flow velocity through the left ventricular outflow tract and effective orifice area indexed to body surface area in Golden Retriever puppies to predict development of subaortic stenosis in adult dogs

OBJECTIVE To evaluate the usefulness of Doppler-derived peak flow velocity through the left ventricular outflow tract (LVOT Vmax) and effective orifice area indexed to body surface area (EOAi) in puppies to predict development of subaortic stenosis (SAS) in the same dogs as adults. DESIGN Prospective, longitudinal, observational study. ANIMALS 38 Golden Retrievers. PROCEDURES Cardiac auscultation and echocardiography were performed on 2- to 6-month-old puppies, then repeated at 12 to 18 months. Subaortic stenosis was diagnosed when LVOT Vmax was ≥ 2.3 m/s in adult dogs with left basilar systolic murmurs. RESULTS All puppies with EOAi < 1.46 cm(2)/m(2) had SAS as adults. All adults with EOAi < 1.29 cm(2)/m(2) had SAS. An LVOT Vmax > 2.3 m/s in puppyhood was 63% sensitive and 100% specific for SAS in adulthood. In puppies, LVOT Vmax was more strongly associated with a future diagnosis of SAS (area under the curve [AUC], 0.89) than was EOAi (AUC, 0.80). In puppies, the combination of LVOT Vmax and EOAi yielded slightly higher sensitivity (69%) and specificity (100%) for adult SAS than did LVOT Vmax alone. In unaffected and affected dogs, LVOT Vmax increased significantly from puppyhood to adulthood but EOAi did not. CONCLUSIONS AND CLINICAL RELEVANCE In Golden Retriever puppies, LVOT Vmax > 2.3 m/s and EOAi < 1.46 cm(2)/m(2) were both associated with a diagnosis of SAS at adulthood. The combination of these 2 criteria may result in higher sensitivity for SAS screening. Unlike LVOT Vmax, EOAi did not change during growth in either unaffected Golden Retrievers or those with SAS.

Congenital coronary-pulmonary arterial shunt in a German shepherd dog: diagnosis and surgical correction.

BACKGROUND A 10 week-old intact female German shepherd dog was examined because of a heart murmur. METHODS An echocardiogram revealed an extracardiac left-to-right shunt. An angiogram identified shunting between the aorta and the pulmonary artery in an unusual location. RESULTS Thoracotomy was performed to better identify and correct the lesion; a tubular shunt between the left coronary artery and the pulmonary artery was found and ligated in a closed-heart procedure. The murmur resolved immediately upon ligation and the dogs heart size normalized over a period of several months after surgery. CONCLUSION In the dog, surgical correction of a coronary artery-pulmonary artery shunt can be performed without complications and can be associated with reversal of cardiac remodeling.

Feline Arrhythmias: An Update

In the cat, electrocardiography is indicated for assessing the rhythm of the heartbeat and identifying and monitoring the effect of certain systemic disorders on the heart. Basic information regarding feline electrocardiography is contained in several textbooks, and the reader is referred to these sources for background reading. This article describes selected clinical advances in feline cardiac arrhythmias and electrocardiography from the past decade.

Association between Aortoseptal Angle in Golden Retriever Puppies and Subaortic Stenosis in Adulthood

Background Predicting subaortic stenosis (SAS) in adult Golden Retriever dogs (GRs) by evaluating them as puppies is hampered by the progressive expression of the SAS phenotype in youth. In some children who develop SAS as adults, an abnormal aortoseptal angle (AoSA) precedes development of stenosis. Objectives To determine the normal AoSA in young adult GRs using echocardiography; to assess the value of AoSA in GR puppies for predicting development of the SAS phenotype. Animals Forty‐eight 2‐ to 6‐month‐old GR puppies. Methods Prospective study. Puppies were recruited from clients and breeders. Puppies were evaluated with a physical examination and an echocardiogram, and this evaluation was repeated when they were 12–18‐month‐old adults. Puppies were classified as unaffected (WNL) or affected (SAS) retroactively, based on their results as adults. Results In WNL young adult GRs, mean ± SD AoSA was 152.3 ± 6.5°. Mean ± SD AoSA in SAS puppies (144.9 ± 8.6°) was significantly different from mean AoSA in WNL puppies (155.7 ± 8.8°, P < .01). No puppy with AoSA >160° had the SAS phenotype as a young adult; 93% (75.7–99.1%) of puppies with AoSA <145° had the SAS phenotype as young adults. Peak LVOT velocity increased significantly between evaluations (P < .0001) whereas AoSA did not (P = .45). Conclusion and Clinical Significance A steep AoSA in GR puppies is associated with the SAS phenotype in young adulthood. Some GR puppies have an abnormal AoSA that persists in young adulthood and is detectable before peak LVOT velocity reaches levels consistent with SAS.