MT10-001: Does treatment of anesthetic-induced hypotension with dopamine or phenylephrine cause myocardial damage in cats with hypertrophic cardiomyopathy?

Hypertrophic cardiomyopathy (HCM) is the most common cardiac disease of clinical significance in cats. Inhalant anesthetics are generally used for maintenance of anesthesia in cats, including those with HCM. However, these drugs produce vasodilation leading to hypotension and reduced myocardial contractility, leading to decreased cardiac output. While the first line of pharmacological intervention to treat anesthetic-induced hypotension usually relies on the administration of a positive inotrope (i.e., dopamine) in patients with HCM, the use of vasoconstrictors (i.e., phenylephrine) has been advocated, because of the disease’s pathophysiology. Use of dopamine as a positive inotrope increases the dynamic obstruction of the ventricular outflow tract and may precipitate myocardial damage by increasing myocardial oxygen consumption. Conversely, vasoconstrictors may increase cardiac output by decreasing dynamic ventricular outflow tract obstruction with less change in myocardial oxygen consumption. In a recent study, the above co-investigators found the effects of dopamine appeared more beneficial than those of phenylephrine in treating isoflurane-induced hypotension in cats with severe HCM. Using samples taken during the prior study, the proposed study will measure troponin I concentration (cardiac myocyte enzymes) in plasma to determine whether increasing myocardial contractility with dopamine results in more myocardial damage than treating hypotension with phenylephrine. The resulting information will help veterinarians make the most appropriate drug choice to treat anesthetic-induced hypotension in cats with hypertrophic cardiomyopathy.

Grant ID: MT10-001

Status: Active

Year Funded: 2010

Amount awarded: $1,134

Investigator: Bruno H. Pypendop, DrMedVet, DrVetSci, Dipl. ACVA; Ashley J. Wiese, DMV, MS.; Linda S. Barter, MVSc, PhD, Dipl. ACVA; Jan E. Ilkiw, BVSc, PhD, Dipl. ECVA, University of California, Davis