Relation between conduction delay and ventricular fibrillation: Characteristics of conduction of premature impulses during acute myocardial ischemia

1981 ◽  
Vol 48 (2) ◽  
pp. 287-294 ◽  
Author(s):  
Toshifumi Fujimoto ◽  
Hiromu Hamamoto ◽  
Thomas Peter ◽  
William J. Mandel ◽  
Avile McCullen
Keyword(s):  
Ventricular Fibrillation ◽  
Myocardial Ischemia ◽  
Acute Myocardial Ischemia ◽  
Conduction Delay

Vagal reflexes and survival during acute myocardial ischemia in conscious dogs with healed myocardial infarction

1991 ◽  
Vol 261 (1) ◽  
pp. H63-H69 ◽  
Author(s):  
G. M. De Ferrari ◽  
E. Vanoli ◽  
M. Stramba-Badiale ◽  
S. S. Hull ◽  
R. D. Foreman ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Heart Rate ◽  
Coronary Artery ◽  
Ventricular Fibrillation ◽  
Myocardial Ischemia ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Acute Myocardial Ischemia ◽  
Acute Ischemia ◽  
Control Test

The role of vagal tone and reflexes in the genesis of life-threatening arrhythmias was investigated in a clinically relevant animal model for sudden cardiac death. Forty-five dogs with a healed anterior myocardial infarction in which transient myocardial ischemia during exercise did not induce malignant arrhythmias were utilized for the study. They underwent a further exercise and ischemia test in which atropine (75 micrograms/kg) was injected before coronary artery occlusion. Novel occurrence of ventricular arrhythmia, or worsening of the type of arrhythmia present in the control test, occurred in 23 of 45 dogs (51%) and ventricular fibrillation occurred in 11 of 45 (24%, P = 0.001). Analysis of heart rate response to acute ischemia in the control test indicates that these 11 animals had powerful vagal reflexes during coronary artery occlusion, compared with the 34 survivors (-32 +/- 35 vs. +2 +/- 27 beats/min, P = 0.003). This study indicates that approximately 75% of animals resistant to ventricular fibrillation are characterized by weak sympathetic reflexes in response to acute myocardial ischemia. In the remaining 25% powerful vagal reflexes counteract concomitant reflex sympathetic hyperactivity, decrease heart rate, and are essential for survival.

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