Ventricular pre-excitation in cats: 17 cases.

OBJECTIVES: Atrioventricular accessory pathways are abnormal electrical connections between the atria and ventricles that predispose to ventricular pre-excitation (VPE) and tachycardias. ANIMALS: Seventeen cats with VPE and 15 healthy matched-control cats. MATERIAL AND METHODS: Multicenter case-control retrospective study. Clinical records were searched for cats with VPE, defined as preserved atrioventricular synchrony, reduced PQ interval, and increased QRS complex duration with a delta wave. Clinical, electrocardiography, echocardiographic, and outcome data were collated. RESULTS: Most cats with VPE were male (16/17 cats), non-pedigree cats (11/17 cats). Median age and mean body weight were 5.4 years (0.3-11.9 years) and 4.6 ± 0.8 kg, respectively. Clinical signs at presentation included lethargy (10/17 cats), tachypnea (6/17 cats), and/or syncope (3/17 cats). In two cats, VPE was an incidental finding. Congestive heart failure was uncommon (3/17 cats). Nine (9/17) cats had tachyarrhythmias: 7/9 cats had narrow QRS complex tachycardia and 2/9 cats had wide QRS complex tachycardia. Four cats had ventricular arrhythmias. Cats with VPE had larger left (P < 0.001) and right (P < 0.001) atria and thicker interventricular septum (P = 0.019) and left ventricular free wall (P = 0.028) than controls. Three cats had hypertrophic cardiomyopathy. Treatment included different combinations of sotalol (5/17 cats), diltiazem (5/17 cats), atenolol (4/17 cats), furosemide (4/17 cats), and platelet inhibitors (4/17 cats). Five cats died, all from cardiac death (median survival time 1882 days [2-1882 days]). CONCLUSIONS: Cats with VPE had a relatively long survival, albeit showing larger atria and thicker left ventricular walls than healthy cats.

Segmental septal dyskinesia associated with an accessory pathway and preexcitation in two Golden Retriever dogs.

Ventricular preexcitation secondary to anterograde conduction through an accessory pathway was diagnosed in two Golden Retriever dogs. Both dogs demonstrated similar segmental myocardial thinning and systolic dyskinesia of the basal interventricular wall on echocardiography. These changes are widely recognised in people with ventricular preexcitation but have not been previously described in dogs. Ventricular preexcitation should be considered as a potential cause for segmental wall motion abnormalities in these two dogs.

Preexcitation alternans in a dog.

Preexcitation alternans and orthodromic atrioventricular reciprocating tachycardia were diagnosed in a 3-month-old Boxer. The images described here show how conventional electrocardiographic techniques (12-lead surface electrocardiography, 24-hour Holter monitoring, and ladder diagram) can be interpreted to gain detailed information on presence of canine atrioventricular accessory pathways and their conduction properties.

Electrocardiographic observation on spontaneously occurring arrhythmias in chickens.

In order to clarify the spontaneous occurrence of arrhythmias in chickens, electrocardiograms using standard bipolar limb leads were recorded for 461 chickens of 7 breeds, including 3 pure breeds: Rhode Island Red (RIR, n = 125), Japanese Game (JG, n = 101), and White Leghorn (WL, n = 52); and 4 crossbreeds of RIR: the first filial generation (F1) obtained by mating RIR with JG (RIR x JG, n = 44), the backcross obtained by mating the Fl of RIR x JG with the parental JG ((RIR x JG) x JG, n = 10), the F1 obtained by mating RIR with WL (RIR x WL, n = 73), and the F1 obtained by mating RIR with the commercial hybrid chicken, Dekalb Amber Link (DAL)(RIR x DAL, n = 56). Nine types of arrhythmias were observed in 107 chickens (23.2%, 107/461): 66 had sinus arrhythmia, 19 had atrial premature contraction, 9 had ventricular preexcitation syndrome, 7 had ventricular premature contraction, 2 had second-degree atrioventricular block. 1 had atrial fibrillation, I had aberrant ventricular conduction. I had intraventricular conduction disturbance, and 1 had ventricular electrical alternans. Except for sinus arrhythmia, the incidence of other arrhythmias in RIR was significantly high, compared with that in pure breeds other than RIR (p < 0.001) and that in crossbreeds of RIR (p < 0.01). Arrhythmias other than ventricular premature contraction and sinus arrhythmia will be the first to be described as spontaneously occurring arrhythmias in chicken. Although the reason for both the highest incidence of sinus arrhythmia in WL and the predominance of other arrhythmias in RIR were obscure, the present results suggest the possibility of using chickens, especially RIR which shows a high incidence of arrhythmias, as a relevant animal for studying arrhythmias.

Ventricular preexcitation in seven dogs and nine cats.

Ventricular preexcitation was diagnosed in 6 dogs and 7 cats examined because of weakness, syncope, or congestive heart failure, and as an incidental finding in 1 dog and 2 cats. Reciprocating tachycardias were documented in 8 of the cases. Six of the cats had a pathologic diagnosis of primary cardiomyopathy. Two of the dogs had an associated congenital heart defect. Reciprocating tachycardias were controlled in 4 cases with digoxin, in 2 cases with propranolol, and in 1 case with quinidine. Conduction through the accessory pathway was altered by quinidine (2 cases), digoxin, and propranolol (1 case each), resulting in a lengthened P-R interval and more normal QRS complex configuration.