Latex-induced transmural
myocardial infarction or epicardial application of
phenol interrupts sympathetic fibers innervating myocardium apical to the
infarction or to the
phenol-painted area. These denervated regions subsequently show supersensitive shortening of effective refractory period (ERP) in response to the infusion of
norepinephrine (
denervation supersensitivity). The purpose of this study was to test the hypothesis that such
denervation supersensitivity is arrhythmogenic. Ventricular arrhythmias were elicited by programmed ventricular stimulation (PVS) during a control period, during bilateral stimulation of the ansae subclaviae (4 msec pulses, 4 Hz and 3 mA), and during the infusion of
norepinephrine (0.5 microgram/kg/min). Study groups consisted of 14
sham-operated dogs, 16 dogs with
phenol painted over a diagonal branch, 13 dogs with
latex embolization of a diagonal branch that resulted in transmural
myocardial infarction, 14 dogs with a one-stage
ligation of a diagonal branch producing nontransmural
myocardial infarction, and 12 dogs undergoing both
phenol painting and one-stage
ligation of a diagonal branch. Four to 22 days after the first operation, PVS was performed in anesthetized, open-chest dogs after neural decentralization of the heart. Dogs with
phenol painting on the epicardium and dogs in which
latex was injected into a diagonal branch showed supersensitive shortening of ERP to infused
norepinephrine at apical sites. PVS resulted in
ventricular fibrillation more often during stimulation of the ansae subclaviae (p less than .001) and infusion of
norepinephrine (p less than .001) than during the control state in dogs treated with
phenol alone. The incidence of
ventricular fibrillation was highest in dogs with
ligation-induced
infarction that received
phenol compared with all other groups during control (p less than .001), stimulation of the ansae subclaviae (p less than .002), and the infusion of
norepinephrine (p less than .01).
Propranolol (0.5 mg/kg or 10 mg iv at maximum) attenuated supersensitive shortening of ERP and decreased the incidence of induction of
ventricular fibrillation.(ABSTRACT TRUNCATED AT 400 WORDS)