TITLE:
Orthodromic Atrioventricular Reciprocating Tachycardia in a Dalmatian
AUTHORS:
Marlos G. Sousa, Stephany B. Lucina, Roberta Carareto
KEYWORDS:
Arrhythmia, Tachycardiomyopathy, Accessory Pathway, Reentrant Arrhythmia
JOURNAL NAME:
Open Journal of Veterinary Medicine,
Vol.8 No.1,
January
23,
2018
ABSTRACT: Supraventricular tachyarrhythmias may be caused by macroreentry circuits involving the AV node and accessory pathways. This paper reports a case of suspected orthodromic atrioventricular reciprocating tachycardia in an 18-month-old Dalmatian admitted with dyspnea and a lifelong history of fatigue. Cardiac auscultation documented a regular fast pace with no heart murmurs. The electrocardiogram characteristics were consistent with supraventricular tachycardia, with very regular RR interval and narrow QRS complexes. At lead II, we identified negative P waves buried within the ST segment, which resulted in a RP-to-PR ratio of 0.60, but in aVR these P waves were positive, suggesting a retrograde conduction of electrical impulses throughout the atrial myocardium. The echocardiographic study showed volume overload, and a decreased fractional shortening was calculated when SVT was sustained, highlighting its impact on systolic function. This is likely the first description of an orthodromic atrioventricular reciprocating tachycardia in a Dalmatian, and although cardiac mapping was not available to confirm this suspicion, all electrocardiograpic features were supportive of such arrhythmia.