Systolic coronary occlusion due to myocardial bridging--a rare cause of ischaemia

Computed tomography of the coronary arteries in diagnosis

IMPORTANCE OF THE FIELD

Cardiac computed tomography (CT) has recently emerged as a non-invasive alternative to catheter angiography for the assessment of coronary artery disease. Rapid technological advances have rendered coronary CT angiography to a robust, accurate and fast imaging modality to assess coronary artery disease in selected patients. The list of further indications in which cardiac CT is an appropriate test remains a topic of discussion.

AREAS COVERED IN THIS REVIEW

This review discusses the main literature available on the use of cardiac CT in the indications considered appropriate in the 2006 Appropriateness Criteria by the American College of Radiology with special emphasis on the temporal trends in the utilization of cardiac CT in clinical practice and in the opinion of the experts, and provides an outlook on how cardiac CT might evolve in the future.

WHAT THE READER WILL GAIN

The reader will gain insight into the strengths and shortcomings of CT of the coronary arteries in coronary artery diagnosis and will learn why cardiac CT is appropriate in some indications but not in others.

TAKE HOME MESSAGE

Recent research in cardiac CT has substantially improved the evaluation of the coronary arteries with CT, and the list of indications cardiac CT is appropriate for might expand further in the coming years.

Comparison of frequency of coronary spasm in Korean patients with versus without myocardial bridging

The longstanding compression-relaxation effects of myocardial bridging may produce endothelial dysfunction by direct stress on the endothelium. We tested the hypothesis that myocardial bridging induces endothelial dysfunction and subsequently increases the risk of coronary spasm and investigated the symptomatic response to medication in patients with documented myocardial bridging and coronary spasm. In 81 patients with myocardial bridging (44 men; mean age 57.2 years) and 195 control patients without bridging and atherosclerotic lesions confirmed by angiography (97 men; mean age 58.4 years), spasm provocation testing was done by incremental acetylcholine infusion into the left coronary artery. Spasm was documented in 62 of 81 patients with bridging and in 31 of 195 controls (p <0.001). A focal spasm was limited to the bridging segments compared with controls (p <0.001). In conclusion, the results of this study showed that myocardial bridging increased the risk of coronary spasm by endothelial dysfunction in the bridging segment.

Systolic compression of the left anterior descending coronary artery: a case series, review of the literature, and therapeutic options including stenting

Six cases in our institution of various presentations of left anterior descending (LAD) myocardial bridging were found on coronary angiography. Generally a benign condition, this finding can result in ischemia or infarction as seen in some of our cases. We found one case in which the bridge resulted in an anterior myocardial infarction in an elderly patient, one case with fixed stenoses at the entry and exit point of the bridge causing ischemia, another with vasospasm within the bridged segment, one case in which the patient was referred for intervention of a fixed stenosis which after intracoronary nitroglycerin (NTG) was found to be an LAD bridge, another case in which the thallium myocardial perfusion scan revealed a reversible anterior defect, and finally one case with anginal chest pain despite a normal coronary flow reserve proximal and distal to the bridged segment. Our treatments varied from stenting in three patients to medical therapy in the remaining patients. We concluded that a thorough evaluation in this population should include functional testing for ischemia, intravascular ultrasound to assess wall thickness, and coronary flow reserve measurements in order to determine the significance of the these bridges. Stenting may have a role in select patients. However, additional studies are needed.

[Long-term prognosis of patients with myocardial bridge and angiographic milking of the left anterior descending coronary artery]

INTRODUCTION

Myocardial bridging with systolic compression (milking) of the left anterior descending coronary artery may be associated with myocardial ischemia. Little information is available about the long-term prognosis of patients with this coronary anomaly.

MATERIAL AND METHODS

A review was made of coronary angiographies of patients diagnosed as ischemic heart disease made between 1994 and 1999 in two centers. The long-term follow-up of patients with myocardial bridging and systolic compression of the left anterior descending coronary artery was analyzed. Data were collected by reviewing medical records and completed by telephone interview.

RESULTS

Prevalence: 0.72%. Milking was observed in 60 patients, but 25 of them were excluded due to associated hypertrophic cardiomyopathy, severe valvular disease, or coronary artery disease. The clinical follow-up was available for all patients (median: 43 months, range: 12-80 months). Mean age 55.7 years (SD = 11.9). Men 74%.

CLINICAL PRESENTATION

angina 26 patients, atypical chest pain with positive non-invasive test 8, acute myocardial infarction 1. During follow-up, 1 patient died of sudden cardiac death. Seven patients continued to present stable angina CCS class I-II, coronary angiography was repeated in 5 patients, and one required percutaneous revascularization for symptoms. In 63% of cases, antianginal drugs were still needed at the end of follow-up period (beta-blockers or calcium antagonists).

CONCLUSIONS

Patients with myocardial bridging and systolic compression of the left anterior descending artery have a good long-term prognosis, although more than half of them continue regular treatment with antianginal drugs. In a small percentage of cases percutaneous intervention must be performed and ischemic heart disease may appear in more aggressive forms (acute myocardial infarction or sudden death).

Dipyridamole TI-201 SPECT imaging in patients with myocardial bridging

PURPOSE: Exercise-induced myocardial perfusion abnormalities have been reported in patients with myocardial bridging, possibly by tachycardia-induced shortening of diastole. Dipyridamole TI-201 SPECT findings were evaluated in patients with myocardial bridging to assess perfusion abnormalities during dipyridamole stress. MATERIALS AND METHODS: Dipyridamole TI-201 SPECT images of 12 patients with myocardial bridging (> or = 50% systolic narrowing) were evaluated. The peak heart rate during dipyridamole stress was less than 110 beats/min in all patients. The control group was 118 patients with fixed left anterior descending artery (LAD) disease. RESULTS: Fourteen sites of systolic arterial narrowing were present in LAD: two in mid-LAD, seven in distal LAD, and five in septal branches. Dipyridamole TI-201 SPECT showed reversible perfusion defects in three of six sites with 50% to 70% systolic narrowing and seven of eight sites with more than 80% systolic narrowing. Overall, 71% (10 of 14) had a reversible perfusion defect. Five patients with septal branch compression had a perfusion defect in the midanteroseptal wall without an apical abnormality. In the control group, no patient had an isolated perfusion defect in the midanteroseptal wall or septal branch disease (5 of 12 compared with 0 of 118; P < 0.001). CONCLUSIONS: Perfusion abnormalities on dipyridamole TI-201 SPECT are observed in LAD or its branches in patients with high-grade myocardial bridging. Myocardial bridging may decrease coronary flow reserve but not necessarily via tachycardia. Isolated perfusion defects in the midanteroseptal wall may be a characteristic finding of septal branch compression, because a fixed lesion involving a septal branch only is rare.

Congenital coronary artery abnormalities

Congenital coronary artery abnormalities are rare and account for approximately 0.1 to 2% of congenital heart defects. They may pose significant risk of mortality or morbidity to the patient. The pediatrician and the pediatric cardiologist should be aware of their subtle but very serious presentations and diagnostic steps to be undertaken to pinpoint the diagnosis. Prevention of serious complications from these abnormalities can be achieved by making the appropriate diagnosis and performing timely surgical intervention. This review will discuss the most common congenital coronary artery abnormalities and their management.

Disturbed intracoronary hemodynamics in myocardial bridging: early normalization by intracoronary stent placement

BACKGROUND

The purpose of this study was to evaluate the hemodynamic mechanisms leading to myocardial ischemia in patients with myocardial bridging. Myocardial bridging is known to induce angina and even severe myocardial ischemia.

METHODS AND RESULTS

In 12 symptomatic patients with myocardial bridges, quantitative coronary angiography was performed to obtain systolic/diastolic vessel diameters within the bridged segments. Coronary flow velocities, flow reserve, and pressures were determined with a 0.014-in Doppler and a 0.014-in pressure microtransducer. In 3 symptomatic patients, coronary stents were implanted and hemodynamic measurements were repeated immediately and after 7 weeks. An in vitro validation of the pressure measurements was performed. Angiography revealed a systolic diameter reduction of 80.6+/-9.2% and a persistent diastolic reduction of 35.3+/-11% within the bridged segment. Diastolic flow velocities (cm/s) were increased (31.5+/-14.3 within versus 17.3+/-5.7 proximal and 15.2+/-6.3 distal, P<.001). Coronary flow reserve distal to the bridge was 2.5+/-0.5. There was an increased peak systolic pressure within the bridged segment (171+/-48 versus 113+/-10 mm Hg proximal, P<.001). Stent placement abolished the phasic lumen compression, the diastolic flow abnormalities, the intracoronary peak systolic pressure, and clinical symptoms. Coronary flow reserve improved to 3.8+/-0.3.

CONCLUSIONS

Coronary hemodynamics in myocardial bridges are characterized by a phasic systolic vessel compression with a localized peak pressure, persistent diastolic diameter reduction, increased blood flow velocities, retrograde flow, and a reduced flow reserve. These alterations may explain the occurrence of symptoms and ischemia in these patients. Intracoronary stent placement abolished all hemodynamic abnormalities and may improve clinical symptoms in otherwise unsuccessfully treated patients with myocardial bridges.

Myocardial bridging prevents safe laparoscopy? A case report

A 49-year-old male presented with atypical chest pain. Complete cardiac evaluation was normal except for cardiac catheterization, which revealed a myocardial bridge across the LAD (left anterior descending coronary artery) that caused a 50% systolic stenosis. Abdominal ultrasound revealed cholelithiasis. The patient became asymptomatic and was discharged only to return with biliary pancreatitis, which resolved over 2 weeks and laparoscopic cholecystectomy was attempted. Upon establishment of a pneumoperitoneum, he began to suffer cardiac ischemia, which immediately resolved upon desufflation. The procedure was converted to an uneventful open cholecystectomy. He did well without any further problems. This is the first report of myocardial bridging, a well-known cardiac anomaly, possibly preventing safe laparoscopy. This was possibly due to transmitted intraperitoneal pressure effect on the pericardium pushing closed that myocardial bridge.

Functional, angiographic and intracoronary Doppler flow characteristics in symptomatic patients with myocardial bridging: effect of short-term intravenous beta-blocker medication

OBJECTIVES

We sought to define the effects of short-term beta-adrenergic blocking medication on intracoronary flow characteristics, clinical symptoms and angiographic diameter changes in patients with severe myocardial bridging of the left anterior descending coronary artery.

BACKGROUND

Controversy exists regarding the pathophysiology, clinical relevance and optimal therapy in symptomatic patients with myocardial bridges because antianginal drugs have not been systematically tested.

METHODS

In 15 symptomatic patients with myocardial bridging of the left anterior descending coronary artery, maximal lumen diameter reductions were evaluated by quantitative coronary angiography. There were no angiographic signs of coronary artery disease. Coronary blood flow velocities (using a 0.014-in. [0.035 cm] Doppler guide wire) were measured at rest, during atrial pacing and during intravenous administration of a short-acting beta-blocker (esmolol, 50 to 500 micrograms/kg body weight per min) with continuous atrial pacing.

RESULTS

The maximal angiographic systolic lumen diameter reduction within the myocardial bridges was 83 +/- 9% at rest, with a persistent diastolic diameter reduction of 41 +/- 11% (mean +/- SD). Short-term intravenous beta-blocker therapy decreased the diameter reduction during both systole (from 83 +/- 9% to 62 +/- 11%) and diastole (from 41 +/- 11% to 30 +/- 9%, both p < 0.001). The average diastolic peak flow velocity was higher within the myocardial bridges (33 +/- 13 cm/s) than the proximal (26 +/- 13 cm/s) and distal bridges (17 +/- 4 cm/s, both p < 0.001). During tachypacing, average diastolic peak flow velocity increased within the bridged segments to 63 +/- 21 cm/s versus 29 +/- 12 cm/s in the proximal and 20 +/- 4 cm/s in the distal bridges (both p < 0.001). Beta-receptor blockade produced a return to baseline values (average diastolic peak flow velocity within bridge 35 +/- 16 cm/s, p < 0.001). ST segment changes and symptoms were abolished with beta-blocker administration.

CONCLUSIONS

In patients with myocardial bridges, administration of short-acting beta-blockers during atrial pacing alleviates anginal symptoms and signs of ischemia. This effect was mediated by a reduction of vascular compression and maximal flow velocities within the bridged coronary artery segment.

Myocardial bridging involving more than one site of the left anterior descending coronary artery: an uncommon cause of acute ischemic syndrome

An infrequent angiographic finding is reported of myocardial bridging involving more than one site of the left anterior descending coronary artery in a symptomatic patient with ischemia exacerbated by nitroglycerin administration. Beta-blocker therapy alone was followed by a favorable long-term outcome.

Intramural left anterior descending coronary artery: significance of the depth of the muscular tunnel

To establish whether an intramural left anterior descending coronary artery (LADA) is a simple anatomic or a singularly pathologic variant we studied 39 hearts, each with an intramural course of the LADA and no coronary artery disease, valvular derangement, cardiomyopathy, or congenital anomaly. Seventeen of the 39 hearts had no myocardial lesions, while 22 had gross and/or microscopic alterations in the myocardial territory supplied by the intramural LADA. The myocardial lesions consisted of one or more of the following: interstitial fibrosis, replacement fibrosis, contraction band necrosis, and/or increased vascular density in areas of focal fibrosis. The coronary anatomy of the 22 hearts with myocardial lesions (group 1) was compared with that of the 17 hearts without myocardial changes (group 2). Each of the group 1 hearts had an intramural LADA deeply placed within the ventricular wall and attenuation of potential collateral blood flow because of a co-existing intramural course of the posterior descending artery, other epicardial coronary arteries, and/or a diminutive right coronary artery. The myocardial changes in group 1 hearts and their absence in group 2 hearts suggest that the deep, intramural LADA of the group 1 hearts is abnormal rather than a simple anatomic variant of normal. Furthermore, the deep intramural LADA may be associated with sudden death since 13 of the 22 group 1 hearts were from sudden death victims. Six of these 13 persons died suddenly during vigorous exercise.