Differential local spasticity in myocardial bridges

Abstract

To illustrate the effect of myocardial bridges on coronary vascular tone, we describe the cases of 2 patients with different clinical presentations in the context of reproducible increased spasticity at the site of myocardial bridging. One had an episode of takotsubo cardiomyopathy, and one developed typical Prinzmetal angina while receiving desmopressin treatment for pituitary insufficiency. In both patients, acetylcholine challenge clearly revealed both the presence and the severity of myocardial bridging while producing several recognizable degrees of abnormal spastic tendency.Both baseline functional states and responses to different medications correlate with spastic tendency and enable the characterization of individual cases. Understanding the spectrum of spastic conditions might help to clarify the causes of atypical ischemic events, especially in patients with myocardial bridging.

Keywords: Acetylcholine/diagnostic use; Prinzmetal angina; angina pectoris, variant; coronary vasospasm/chemically induced/diagnosis; endothelial dysfunction; myocardial bridging; takotsubo cardiomyopathy.

Fig. 1 Patient 1. Baseline coronary angiogram of the left coronary artery shows no significant fixed stenosis. There is a hint of proximal left anterior descending coronary artery systolic compression. Real-time motion image is available at www.texasheart.org/journal.

Fig. 2 Patient 1. Systolic frame from baseline 4-chamber echocardiogram, taken during the patient's early recovery period, shows mild residual apical hypokinesia in a subacute phase of recovery after an episode of takotsubo cardiomyopathy. Real-time motion image is available at www.texasheart.org/journal.

Fig. 3 Patient 1. A) Cine coronary angiogram during infusion of 25 µg of acetylcholine (ACH 25) shows an extreme and diffuse spastic reaction. B) Systolic frame from a simultaneously obtained left ventricular echocardiogram shows the reproduction of severe apical dyskinesia and cavity dilation. Real-time motion images are available at www.texasheart.org/journal.

Fig. 4 Patient 1. Coronary angiograms from a felodipine/acetylcholine (ACH) test. A) To test the effect of a calcium antagonist in preventing spasm, 200 µg of felodipine was used before a repeat test with 25 µg of acetylcholine. B) Significant fixed, localized stenosis (spasm) appears at the level of the proximal left anterior descending myocardial bridge. C) Nitroglycerin promptly relieved the spasm, as indicated by phasic systolic narrowing typical of a myocardial bridge. Real-time motion images of Figures 4A and 4B are available at www.texasheart.org/journal.

Fig. 5 Patient 2. A) Baseline angiographic frame during systole indicates a myocardial bridge at the proximal left anterior descending coronary artery. B) After the administration of 75 µg of acetylcholine, subtotal obstruction of the same segment occurred. C) Nitroglycerin (NTG) eliminated the fixed stenosis; however, more obvious systolic narrowing of the myocardial bridge occurred. Real-time motion images are available at www.texasheart.org/journal.