TRANSESOPHAGEAL ECHOCARDIOGRAPHY OF THE LEFT VENTRICULAR OUTFLOW TRACT, AORTIC VALVE AND ASCENDING AORTA IN BOXER DOGS WITH HEART MURMURS

Heartworm Removal Guided by Transesophageal Echocardiography in a Dog with Naturally Acquired Caval Syndrome

A 14 mo old shih tzu was referred for dyspnea, hemoptysis, and hematuria. Heartworm disease with caval syndrome was diagnosed by laboratory tests, thoracic radiography, and transthoracic echocardiography. The minimally invasive heartworm removal procedure was performed using flexible alligator forceps guided by transesophageal echocardiography. The procedure was successfully performed removing over 94% of heartworms displayed echocardiographically without any intraoperative complication.

The influence of emotional stress on Doppler-derived aortic peak velocity in boxer dogs

Background

Subaortic stenosis (SAS) is a common congenital heart disease in Boxers. Doppler‐derived aortic peak velocity (AoPV) is a diagnostic criterion for the disease.

Objectives

To investigate the influence of emotional stress during echocardiographic examination on AoPV in normal and SAS‐affected Boxers. To evaluate the effects of aortic root diameters on AoPV in normal Boxers.

Dogs

Two hundred and fifteen normal and 19 SAS‐affected Boxers.

Methods

The AoPV was recorded at the beginning of echocardiographic examination (T0), and when the emotional stress of the dog was assumed to decrease based on behavioral parameters and heart rate (T1). AoPV0–AoPV1 was calculated. In normal dogs, stroke volume index was calculated at T0 and T1. Aortic root diameters were measured and their relationship with AoPV and AoPV0–AoPV1 was evaluated.

Results

In normal dogs, AoPV was higher at T0 (median, 1.95 m/s; range, 1.60–2.50 m/s) than at T1 (median, 1.76 m/s; range, 1.40–2.20 m/s; P < .0001; reduction 9.2%). The stroke volume index at T0 also was greater than at T1 (P < .0001). Weak negative correlations were detected between aortic root size and aortic velocities. In SAS‐affected dogs, AoPV0 was higher than AoPV1 (P < .0001; reduction 7.3%).

Conclusion and Clinical Importance

Aortic peak velocity was affected by emotional stress during echocardiographic examination both in SAS‐affected and normal Boxers. In normal Boxers, aortic root size weakly affected AoPVs, but did not affect AoPV0–AoPV1. Stroke volume seems to play a major role in stress‐related AoPV increases in normal Boxers. Emotional stress should be taken into account when screening for SAS in the Boxer breed.

Advanced techniques in echocardiography in small animals

Transthoracic echocardiography has become a major imaging tool for the diagnosis and management of canine and feline cardiovascular diseases. During the last decade, more recent advances in ultrasound technology with the introduction of newer imaging modalities, such as tissue Doppler imaging, strain and strain rate imaging, and 2-dimensional speckle tracking echocardiography, have provided new parameters to assess myocardial performance, including regional myocardial velocities and deformation, ventricular twist, and mechanical synchrony. An outline of these 4 recent ultrasound techniques, their impact on the understanding of right and left ventricular function in small animals, and their application in research and clinical settings are given in this article.

Use of auscultation and Doppler echocardiography in Boxer puppies to predict development of subaortic or pulmonary stenosis

BACKGROUND

Boxers are predisposed to subaortic and pulmonic stenosis (SAS, PS). Screening of puppies may be useful in estimating the risk of their developing a defect that potentially compromises life expectancy or exercise tolerance.

HYPOTHESIS

Presence of SAS or PS in adult Boxers can be predicted by auscultation and Doppler echocardiography at 9-10 weeks of age.

ANIMALS

Eighty-five Boxer puppies examined at 9-10 weeks of age and at 12 months of age.

METHODS

Prospective, longitudinal observational study. Auscultation by stethoscope and continuous wave-Doppler echocardiography for peak velocities (V(max)) in the aorta (Ao) and pulmonary artery (PA).

RESULTS

Intensity of heart murmurs in puppies correlated with V(max)Ao and V(max)PA in adults. V(max)Ao and V(max)PA in puppies correlated with V(max)Ao and V(max)PA in adults, respectively. From puppy to adult, V(max)Ao increased and V(max)PA remained unchanged. The negative predictive value for absent or only a soft (< or =II/VI) murmur in puppies being associated with V(max)Ao and PA < or = 2.4 m/s as an adult was 90% and < or =3.5 m/s 100%. The negative predictive value of a V(max)< or = 2.4 m/s as a puppy still being < or =2.4 m/s as an adult was 94% for Ao and 96% for PA, and of a V(max)< or = 3.5 m/s, 99% for Ao and 100% for PA.

CONCLUSIONS AND CLINICAL IMPORTANCE

Even though V(max)Ao increases during growth in Boxer puppies, indicating relative narrowing of the aorta, puppies with V(max)Ao < or = 2.4 m/s do not usually progress to clinically have relevant SAS at 12 months of age.

Tachycardia-induced cardiomyopathy in a young Boxer dog with supraventricular tachycardia due to an accessory pathway

A 1-year-old male Boxer dog presented with sustained supraventricular tachycardia and tachycardia-induced cardiomyopathy. Conversion to sinus rhythm was achieved initially with intravenous lignocaine and subsequently with oral procainamide. Oral procainamide treatment was relatively successful in maintaining normal sinus rhythm with no side effects apart from a reversible change in coat colour. Electrophysiological studies demonstrated the presence of an accessory pathway connecting the right atrium to the right ventricle and confirmed the diagnosis of orthodromic atrioventricular reciprocating tachycardia. Radiofrequency catheter ablation of the accessory pathway led to permanent resolution of the supraventricular tachycardia and for 9.5 years the dog has had no further signs of cardiac disease. The successful treatment of this condition highlights the importance of differentiating tachycardia-induced cardiomyopathy from dilated cardiomyopathy.