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Anesthesia in the Patient with Cardiac Disease

Bruno H. Pypendop

Key Points

• Anesthetic management of cats with heart disorders is based on the underlying heart structure, which can be divided into five
functional categories:
• Systolic myocardial failure (e.g., dilated cardiomyopathy)
• Diastolic dysfunction (increased ventricular wall thickness or other forms of ventricular wall stiffening, e.g., hypertrophic
cardiomyopathy [HCM], restrictive cardiomyopathy [RCM])
• Ventricular volume overload (e.g., ventricular septal defect)
• Ventricular volume underload (e.g., dehydration)
• Structurally normal heart (e.g., physiologic heart murmur)
• Preanesthetic preparation includes assessment of the state of cardiac disease with a minimum database (CBC, serum chemistry
profile, urinalysis), thoracic radiographs, electrocardiogram, blood pressure, and optimally an echocardiogram.
• Cardiac medications, with the exception of angiotensin converting enzyme (ACE) inhibitors, should be administered the
morning of anesthesia.
• Correction of anemia and electrolyte disturbances prior to anesthesia is recommended as an important step toward minimizing
anesthetic risk.
• An anesthetic induction protocol with minimal cardiovascular adverse effects in most stable, asymptomatic cats is propofol
and a benzodiazepine (diazepam or midazolam) for induction, and isoflurane or sevoflurane for maintenance. For cats with
symptomatic disease, the preferred technique is induction with etomidate and a benzodiazepine and maintenance with
isoflurane or sevoflurane.
• In cats with significant heart disease (e.g., cardiac enlargement on thoracic radiographs or echocardiogram), lower IV fluid
rates of 3–5 ml/kg/hr are recommended to avoid fluid overload and precipitation of congestive heart failure.
• Intra-anesthetic hypotension is initially managed by reducing the anesthetic concentration to as low as possible and careful
intravenous fluid resuscitation (3–5 ml/kg IV with additional volume titrated if necessary) if hypovolemia is present.
• Persistent hypotension is managed by administering either vasoconstrictors (phenylephrine) in cats with diastolic dysfunction
(e.g., thickened ventricular walls), or positive inotropes (dobutamine or dopamine) in cats with myocardial failure or eccentric
hypertrophy.
• Cardiac biomarkers (plasma NT-proBNP, serum cardiac troponins) are not known to help stratify anesthetic risk in cats and do
not replace the minimum database for preanesthetic screening.

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.

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