Chest Pain + Bezold-Jarisch Reflex

Thanks to Dr. Levin today for her case of chest pain which reminded us of coronary anatomy distribution on ECGs and post-MI complications. It also highlighted the importance of good sign-out during transitions of care.

 Image adopted from  ecgwaves.com  for reference. 

Image adopted from ecgwaves.com for reference. 

Remember to correlate the ST changes on the ECG to the myocardial territory and the coronary anatomy. This will help you think through complications and what other tests may be useful (i.e. posterior or right sided ECG).

ecg.PNG

One complication of myocardial ischemia is arrhythmia. Many may recall that the SA node is supplied by the RCA (60%) or LCX (40%) and, the AV node is supply by the RCA (90%) or LCX (10%). Thus, RCA infarcts can lead to bradycardia via loss of blood supply to those regions. However, another physiologic response called the Bezold-Jarisch Reflex (BJR) is another explanation for arrhythmias. The BJR plausits that myocardial ischemia results in hypotension and bradycardia via stimulation of the cardioinhbitory C fiber afferent receptors in the myocardium. The greatest concentration of these fibers are in the inferior and posterior wall of the heart which just so happen to be supplied by the RCA and LCX. This reflux was thought to be the result of the transient bradycardia and hypotension in this patient who had a distal RCA occlusion on coronary angiogram. For more information of the BJR take a look at this review article in Anesthesiology from 2003.

For additional review on chest pain and CAD diagnosis, evaluation and treatment, please see Dr. Lesselroth's handy pocket cards.