Neurocardiogenic Syncope Following Inferior MYOCARDIAL Infarction; Reports of a new phenomenon.
David O'Donnell*, Angas Hamer, Mark Horrigan,
Austin and Repatriation Medical Centre, Heidleberg Victoria
Neurocardiogenic Syndromme (NCS) results from stimulation of mechanoreceptors in the posterior left ventricular wall, which is heavily supplied with parasympathetic nerve fibres. Inappropriate autonomic responses result in pre-syncope and syncope in susceptible individuals.
Six patients(pts) developed typical NCS for the first time following inferior myocardial infarction. Five males mean age 52 years (48-57) and a female aged 73, developed NCS for the first time within three months of a Q-wave inferior myocardial infarction. All pts had a significant regional wall motion abnormality. In five patients myocardial perfusion imaging studies were performed; in each case there was evidence of infarction with minimal reversible ischaemia. Coronary angiography was performed in all six patients. In 2 pts the right coronary artery (RCA) was occluded and in 2 pts the RCA was critically diseased- these 4 pts underwent balloon angioplasty and stent insertion with minimal residual stenosis. The other two pts had a diseased RCA but with minimal ischaemia on perfusion studies, intervention was not performed. The culprit lesion in each case was in the distal RCA before the crux.
Five patients underwent Tilt Table Tests (TTT), each of which was clearly positive. The predominant response was cardioinhibitory in the four male patients and vasodepressor in the older female patient. The sixth patient had such severe and distressing symptoms it was felt that a TTT was not warranted.
Conclusion: Six patients developed NCS for the first time following Q-wave inferior myocardial infarction with a culprit lesion in the distal RCA. This is the first report of the association of NCS and myocardial infarction. Alterations in structure or function of the posterior wall of the left ventricle may precipitate NCS in pts with susceptible autonomic responses.
