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Ventricular Arrhythmias 1033

Chronic Treatment Possible Complications • Do not use drugs of similar classes to those
used before development of the disease.
One or more may be indicated: Tissue necrosis and secondary infection; sep- • Monitor closely for adverse reactions to
VetBooks.ir • Pentoxifylline (increases erythrocyte plastic- have nondermatologic manifestations (e.g., Prevention Diseases and Disorders
ticemia. Underlying cause of vasculitis might
• Consider doxycycline while awaiting infec-
therapy.
tious disease titers.
dermatomyosytis can cause myositis; SLE can
ity) 15-25 mg/kg PO q 12h or 10-15 mg/
kg q 8h; give after a meal cause protein-losing nephropathy). Vaccinate dogs with caution if there is a history
• Tetracycline and niacinamide >10 kg, Recommended Monitoring of rabies vaccine–induced vasculitis; repeat
500 mg of each drug PO q 8h (<10 kg, Depends on disease and treatment; monitor for occurrences and risk of a generalized vasculitis
250 mg of each drug) for a minimum of adverse reactions to drug therapies as appropriate. or anaphylactic reaction have been suggested.
3 months; tapering is based on a favorable
response. PROGNOSIS & OUTCOME Technician Tips
• Prednisone or prednisolone 2-4 mg/kg PO To reduce the risk of a nondiagnostic sample,
q 24h starting dose, tapering is based on a • Some cases resolve, whereas others are chronic be careful not to biopsy the center of an ulcer;
favorable response. or recurrent. Damage to other organs (renal, the margin of a lesion or an elliptical incision
• Azathioprine (dogs) 2.2 mg/kg PO q neurologic) also affects prognosis. is recommended.
24h for the first 1-3 weeks, then q 48h (with • Proliferative thrombovascular necrosis of the
prednisone or prednisolone) pinnae: varied response may require surgery. Client Education
• Chlorambucil (cats) 0.1-0.2 mg/kg PO q • Idiopathic: may require long-term/indefinite Long-term treatment (4-6 months, sometimes
24-48h (with prednisolone) treatment indefinitely) is often needed.
• Dapsone (dogs) 1 mg/kg PO q 8h • Urticarial: depends on identification of
• Sulfasalazine (dogs) 22-44 mg/kg PO q 8h underlying cause; rule out food allergy (p. 345). SUGGESTED READING
• Cyclosporine 5 mg/kg PO q 24h Innera M: Cutaneous vasculitis in small animals. Vet
• Tacrolimus 0.1% topically q 12h, can be con- PEARLS & CONSIDERATIONS Clin North Am Small Anim Pract 43:113-134,
sidered in cases with focal disease, especially 2013.
as a substitute for topical corticosteroids. Comments AUTHOR: Stephen Waisglass, DVM, CertSAD, DACVD
Wear gloves to apply. • Multiple skin biopsies are the key to EDITOR: Manon Paradis, DMV, MVSc, DACVD
diagnosis.

Ventricular Arrhythmias Bonus Material Client Education
Online
Sheet

BASIC INFORMATION GENETICS, BREED PREDISPOSITION HISTORY, CHIEF COMPLAINT
• Boxers: arrhythmogenic cardiomyopathy Incidental finding (more common):
Definition (p. 76) • Animal is presented for evaluation of a
• Ventricular arrhythmias are electrical • Doberman pinschers and other dog breeds: disorder other than syncope.
discharges occurring spontaneously in the dilated cardiomyopathy (p. 263) • Arrhythmia is noted during physical exam
ventricles. • German shepherds: inherited VT of young or subsequent monitoring.
• The term ventricular premature complex(es) adults Clinically overt:
(VPCs) applies to one, two, or three con- • Large-breed dogs: splenic masses, gastric • Syncope/episodic collapse
secutive premature ventricular impulses, dilation/volvulus (GDV) • Episodic stumbling, disorientation, confusion
whereas four or more in a row are defined • Cats (males > females): hypertrophic • Animal may be well (and even playful and
as ventricular tachycardia (VT). cardiomyopathy (p. 505) active) before and after episodes or may be
• VT involves a ventricular rate of 180 beats/ lethargic, weak, or anorexic.
min or more in dogs and 240 beats/min or RISK FACTORS
more in cats. • Outdoor, roaming dogs: traumatic myocar- PHYSICAL EXAM FINDINGS
• Strictly speaking, this chapter focuses on ditis (hit by car) Incidental finding:
ventricular tachyarrhythmias (not ventricular • Primary heart disease or systemic disturbance, • Physical exam findings reflect the underly-
escape rhythms); for simplicity, the term if sufficiently severe, can cause ventricular ing disorder, but an arrhythmia is noted on
ventricular arrhythmia is used for designating arrhythmias. physical exam.
VPCs and VT. • With VT, the arrhythmia is rapid and
GEOGRAPHY AND SEASONALITY may be irregular (usually polymorphic on
Synonyms Chagas’ disease: myocarditis (southern parts of electrocardiogram [ECG]) or regular (usually
• Ventricular ectopy, extrasystoles, or tachyar- the United States and Latin America) monomorphic on ECG).
rhythmias • Pulse deficit
• VPCs are synonymous with premature ASSOCIATED DISORDERS ○ Premature heartbeat ausculted, without
ventricular complexes (PVCs), premature Syncope (rapid VT) a corresponding palpable pulse for that
ventricular depolarizations (PVDs), and Clinical Presentation beat
similar variations. ○ Common with ventricular arrhythmias
DISEASE FORMS/SUBTYPES ○ Depends on the degree of prema-
Epidemiology • Incidental finding turity of VPCs (how underfilled are
SPECIES, AGE, SEX • Clinically overt (e.g., causing syncope) the ventricles when the VPC causes
Any animal can be affected. • Accelerated idioventricular rhythm (AIVR) contraction?)

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