Page 87 - Feline Cardiology

10

Congenital Heart Malformations

Key Points

• Congenital heart malformations occur in a small proportion of feline cardiology patients (<10% of cases).
• In general, echocardiography will be needed to diagnose the exact malformation because there is a tremendous amount of
overlap between physical examination, electrocardiographic, and radiographic findings for most malformations.
• Treatment is generally directed at controlling clinical signs that may develop due to heart failure or arrhythmias because
treatment of the primary defect is not usually possible.

INTRODUCTION malformations are patent ductus arteriosus, aortic ste-
nosis, tetralogy of Fallot, atrial septal defect, common
Congenital heart malformations are developmental atrioventricular canal, and pulmonic stenosis (Riesen
defects of the heart that are present at birth. They may et al. 2007).
be inherited or may develop spontaneously without any
known familial pattern.
In general, feline congenital heart disease is much less HISTORY AND CHIEF COMPLAINT
common than acquired heart diseases like the cardiomy- Many kittens and cats with congenital heart malforma-
opathies. Approximately 5% of cats examined by the tions are asymptomatic, but in others, clinical signs may
cardiology service at the School of Veterinary Medicine be intermittent and include exercise intolerance, syncope,
at the University of California-Davis over a 10-year and dyspnea. Animals that have progressed to the point
period were diagnosed with a congenital heart malfor- of development of congestive heart failure may show
mation (MacDonald 2006). A recent study from two other vague clinical signs including loss of appetite,
veterinary cardiology services in Switzerland identified depression, and exercise intolerance.
that 12% of the feline cardiology cases had congenital
heart disease (Riesen et al. 2007). A prospective study of PHYSICAL EXAMINATION
circulating biomarkers in cats presented to a private
referral practice revealed a ratio of myocardial disease to In many cases, careful evaluation of a juvenile cat with
congenital heart malformations of 23:1 (Ettinger 2010). a congenital heart malformation defect will identify a
The most commonly reported feline congenital heart heart murmur and/or arrhythmia, although some cases
malformations are mitral and tricuspid valve malforma- may not have any auscultatory abnormalities. The loca-
tions and ventricular septal defects, although which tion and timing of the murmur can help to narrow the
defect is actually more common seems to vary depend- differential diagnosis list substantially (see Chapter 1).
ing on the study. Less commonly reported feline heart Cyanosis may be noted in some cases.

Feline Cardiology, First Edition. Etienne Côté, Kristin A. MacDonald, Kathryn M. Meurs, Meg M. Sleeper.
© 2011 John Wiley & Sons, Inc. Published 2011 by John Wiley & Sons, Inc.

85