Evaluation of a new smartphone-based digital stethoscope featuring phonocardiography and electrocardiography in dogs and cats.

This study assessed a new smartphone-based digital stethoscope (DS) featuring simultaneous phonocardiographic and one-lead electrocardiogram (ECG) recording in dogs and cats. The audio files and ECG traces obtained by the device were compared with conventional auscultation and standard ECG. A total of 99 dogs and nine cats were prospectively included. All cases underwent conventional auscultation using an acoustic stethoscope, standard six-lead ECG, standard echocardiography and recordings with the DS. All the audio recordings, phonocardiographic files and ECG traces were then blind reviewed by an expert operator. The agreement between methods was assessed using Cohen's kappa and the Bland-Altman test. Audio recordings were considered interpretable in 90% animals. Substantial agreement was found in the diagnosis of heart murmur (κ = 0.691) and gallop sound (k = 0.740). In nine animals with an echocardiographic diagnosis of heart disease, only the DS detected a heart murmur or gallop sound. ECG traces recorded with the new device were deemed interpretable in 88 % animals. Diagnosis of heart rhythm showed moderate agreement in the identification of atrial fibrillation (k = 0.596). The detection of ventricular premature complexes and bundle branch blocks revealed an almost perfect agreement (k = 1). Overall, the DS showed a good diagnostic accuracy in detecting heart murmurs, gallop sounds, ventricular premature complexes and bundle branch blocks. A clinically relevant overdiagnosis of atrial fibrillation was found but without evidence of false negatives. The DS could represent a useful screening tool for heart sound abnormalities and cardiac arrhythmias..

Noninvasive electrocardiographic parameters to assess interventricular dyssynchrony in dogs with bundle branch blocks.

OBJECTIVES: To define electrocardiographic features of complete left bundle branch block (LBBB) and right bundle branch block (RBBB), and the use of R-peak time (RPT) to identify interventricular dyssynchrony in dogs with BBB. ANIMALS, MATERIALS AND METHODS: Twelve-lead ECG tracings of 20 dogs with RBBB, 20 with LBBB, and 60 healthy dogs were retrospectively analyzed and RPT was measured in precordial leads. Interventricular dyssynchrony index (IDI) was than calculated. RESULTS: In RBBB, mean electrical axis (MEA) was -111° [-120/-100°], V1RPT was significantly longer (61 ms [55-72 ms]) than left precordial leads RPT (V2:25 ms [22-30 ms]; V3:25 ms [22-29 ms]; V4:24 ms [21-29 ms]; V5:25 ms [22-29 ms]; V6:25 ms [22-29 ms]) and when compared to normal dogs (P < 0.001). In LBBB, MEA was 76° [70/81°], RPT in left precordial leads was significantly longer (V2:49 ms [34-58 ms]; V3:49 ms [43-57 ms]; V4:52 ms [45-62 ms]; V5:53 ms [45-63 ms]; V6:55 ms [45-63 ms]) than V1RPT (17 ms [15-20 ms]) and when compared to normal dogs (P < 0.001). V1RPT > 28 ms and V5RPT > 36 ms were found to predict the presence of RBBB and LBBB with a sensitivity of 100% and 96.7%, and a specificity of 96.7% and 99.5%, respectively. The IDI was 23% [16-29%] in normal dogs and significantly greater in dogs with RBBB (33% [30-38%]; P < 0.001) and LBBB (32% [23-41%]; P = 0.006). CONCLUSIONS: This study defines ECG features and RPT in dogs with BBB. Electrical interventricular dyssynchrony can be defined using IDI in dogs with BBB.

Three-dimensional electroanatomic mapping and radiofrequency catheter ablation of ventricular arrhythmia in a dog without structural heart disease.

A 1.5-year-old, female-spayed mix-breed dog was presented with recurrent episodes of shaking and excessive panting attributed to drug-refractory ventricular arrhythmia (VA) characterized predominantly by incessant periods of ventricular bigeminy. The VA had a narrow QRS morphology, suggestive of an origin near the His bundle or fascicular system. Diagnostic evaluation found no structural heart disease or underlying etiology. Three-dimensional electroanatomic mapping and radiofrequency catheter ablation were pursued. Voltage mapping demonstrated normal bi-ventricular voltage (≥1.5 mV) without any fractionated or multicomponent electrograms, indicating the absence of ventricular myocardial scar. Pace mapping identified an endocardial origin of the VA at the basal anterior septum of the left ventricle, distal to the His bundle and near the left bundle branch. Two ablation lesions were delivered to this site, and a left bundle branch block was temporarily induced. The dog recovered uneventfully. One month later, the owners reported a remarkable improvement in clinical signs, and follow-up 48-h Holter monitor found complete resolution of VA.

Trifascicular block in a cat infected with Cytauxzoon felis.

A 3-year-old female spayed indoor/outdoor Siamese cat was diagnosed with cytauxzoonosis and irregular heart rhythm was appreciated during a physical examination. On electrocardiogram, the cat had an average ventricular rate of 144 beats/min with Wenckebach type (Mobitz type I) atrioventricular block. The QRS complexes of sinus conducted beats had left anterior fascicular block morphology, they were followed by two subsequent beats presented with a prolonged P-R interval and QRS conducted with a left bundle branch block. The finding of alternating left anterior fascicular block and left bundle branch block along with atrioventricular block is consistent with trifascicular block. No structural heart changes were noted on echocardiography. Approximately 48 h after presentation to the emergency service, the cat acutely decompensated and spontaneously died.

Transient myocardial thickening in a Bartonella henselae-positive cat.

A 3-year-old castrated male domestic shorthair presented to the Cornell University Hospital for Animals for acute onset respiratory distress. Thoracic radiographs, echocardiogram, and electrocardiogram (ECG) revealed left-sided congestive heart failure, myocardial thickening with left atrial dilation, and sinus rhythm conducted with a left bundle branch block, respectively. Cardiac troponin I was elevated and continued to increase over 36 h (1.9 ng/mL, 3.1 ng/mL, and 3.5 ng/mL, sequentially every 12 h). The cat tested positive for Bartonella henselae and was treated with azithromycin (30 mg/kg by mouth (PO) every 24 h for 30 days), along with furosemide (1 mg/kg PO every 24 h), benazepril (0.4 mg/kg PO every 24 h), pimobendan (0.23 mg/kg PO every 12 h), and clopidogrel (18.75 mg PO every 24 h). Reevaluation at 6 weeks revealed normal respiratory rate on physical examination, normal cardiac structures and function on echocardiogram, resolution of left bundle branch block on ECG, and normal cardiac troponin I levels (0.06 ng/mL). All medications were discontinued at this time, and the cat continued to do well 5 months after reevaluation. Here, we report a case of transient myocardial thickening in a cat that was also positive for B. henselae.

Usefulness of dyssynchrony indices based on two-dimensional speckle tracking echocardiography in a canine model of left bundle branch block.

INTRODUCTION: Determine the usefulness of dyssynchrony indices derived from two-dimensional speckle tracking echocardiography for the detection of mechanical dyssynchrony in a canine model of left bundle branch block. ANIMALS: Ten healthy beagles. MATERIALS AND METHODS: Segmental, time-radial strain curves were obtained using two-dimensional speckle tracking echocardiography. The maximum difference and standard deviation of the time to peak radial strain for six predefined segments (MaxD-TpSR and 6SD-TpSR) were calculated, together with the left ventricular dyssynchrony by radial strain (DysSR), before and after ablation of the left bundle branch block. Receiver operating characteristic curve analysis was performed using dogs after ablation as positive controls. RESULTS: After ablation, all dogs showed multiple peaks in at least one segment on the time-radial strain curve, while all dyssynchrony indices increased significantly (MaxD-TpSR from 16.25 ± 16.04 [mean ± standard deviation] to 44.4 ± 26.18 ms, 6SD-TpSR from 7.59 ± 7.40 to 19.62 ± 11.91 ms, and DysSR from 4.20 ± 2.12 to 10.87± 2.92%, p<0.05). In receiver operating characteristic curve analysis, the areas under the curve for MaxD-TpSR, 6SD-TpSR, and DysSR were 0.825, 0.800, and 0.980, respectively. CONCLUSIONS: Left ventricular dyssynchrony by radial strain can detect mechanical dyssynchrony with higher sensitivity and specificity than dyssynchrony indices, based on the time to peak radial strain.

Arrhythmogenic right ventricular cardiomyopathy in boxers.

Arrhythmogenic right ventricular cardiomyopathy, formerly termed boxer cardiomyopathy, is a familial primary myocardial disease that is prevalent in boxers. Unique histopathologic changes in the myocardium lead to conduction abnormalities that typically manifest as ventricular tachyarrhythmias with left bundle branch block morphology. Affected dogs can be asymptomatic or may have syncope and/or exercise intolerance. Diagnosis can be difficult, and indications for antiarrhythmic therapy are not always clear. A small number of dogs present with systolic dysfunction and/or congestive heart failure. Screening in asymptomatic breeding dogs was difficult until the recent development of genetic testing.

Ebstein's anomaly in a beagle dog.

An intact male beagle dog aged 1 year was referred because of shortness of breath, exercise intolerance and cardiac murmur. Based on the results from electrocardiography, thoracic radiography and echocardiography, the dog was diagnosed as Ebstein's anomaly. Although the orally administered digoxin, vasodilators and diuretics partially improved congestive signs, the dog became to be refractory and died 20 months after the diagnosis. Necropsy confirmed malformation and apical displacement of the basal attachment of tricuspid valve leaflets.