Utility of 12-lead electrocardiogram for differentiating paroxysmal supraventricular tachycardias in dogs.

BACKGROUND: The 12-lead surface ECG is validated for differentiating supraventricular tachycardias (SVT) in humans. Despite the description of SVT in veterinary medicine, no studies have analyzed the electrocardiographic features of this type of arrhythmias in dogs. OBJECTIVE: To describe the specific electrocardiographic criteria used to differentiate the most common SVT in dogs. ANIMALS: Twenty-three dogs examined at Clinica Veterinaria Malpensa for SVT with the mechanism documented by electrophysiologic studies (EPS). METHODS: Twelve-lead electrocardiographic variables obtained from 14 dogs with orthodromic atrioventricular reciprocating tachycardia (OAVRT) and 9 dogs with focal atrial tachycardia (FAT) were compared. RESULTS: Dogs with FAT had faster heart rates (278 +/- 62 versus 229 +/- 42 bpm; P= .049) and less QRS alternans (33 versus 86%; P= .022). P waves appeared during tachycardia in 22 dogs, with a superior axis in 100% of OAVRT and 22% of FAT (P < .001). OAVRT was characterized by a shorter RP interval (85.0 +/- 16.8 versus 157.1 +/- 37.3 ms; P < .001) and smaller RP/PR ratio (0.60 +/- 0.18 versus 1.45 +/- 0.52; P < .001). Repolarization anomalies were present in 64% of OAVRT and no FAT (P < .001). Multivariate analysis identified QRS alternans and a positive P wave in aVR during tachycardia as independent predictors of arrhythmia type. CONCLUSION AND CLINICAL IMPORTANCE: Electrocardiographic criteria used in people for differentiating SVT can also be applied in dogs.

An intestinal neuroendocrine tumour associated with paroxysmal ventricular tachycardia and melaena in a 10-year-old boxer.

A 10-year-old female neutered boxer was presented with a five-week history of episodic collapse and melaena. Twenty-four-hour electrocardiograph (Holter) analysis revealed the collapsing episodes to coincide with episodes of paroxysmal ventricular tachycardia. Investigation of the dog's melaena revealed a gastric ulcer which was treated medically and an ileocaecal mass which was surgically excised. Histopathological examination of the mass was consistent with a neuroendocrine (carcinoid) tumour. The patient's recovery after surgery was unremarkable. At six-week follow-up, there had been no further episodes of melaena or collapse and repeat Holter analysis did not show any significant abnormalities. In this dog the gastric ulceration and paroxysmal ventricular tachycardia could be attributed to a paraneoplastic syndrome as a result of circulating vasoactive substances released by the tumour; this is supported by the evidence that all clinical signs resolved after surgical excision of the mass and the dog was clinically well 18 months after surgery.

Atrial paroxysmal tachycardia in dogs and its management with homeopathic Digitalis--two case reports.

Homeopathic Digitalis 6c was evaluated in two clinical cases of atrial paroxysmal tachycardia in dogs. Tachycardias are common cardiac problems in dogs, and atrial paroxysmal tachycardia is a serious cardiac arrhythmia that may lead to syncope. Both adult dogs (Labrador and German Shepherd) were treated with Digitalis 6c, 4 drops orally four times daily for 7 days. Following treatment with Digitalis 6c heart rate stabilised and synchronized atrial and ventricular electrical activity was restored in 7 days.

[Electrocardiography in the horse. (2). Disorders of impulse formation and impulse conduction]. / Elektrokardiographie beim Pferd. (2). Erregungsbildungs-und Erregungsleitungsstörungen.

The cardiac arrhythmias, classified in disturbances of impulse formation and conduction disturbances, their genesis and clinical significance are described and illustrated with electrocardiograms, registered with the bipolar chest leads.