Acute myocardial infarction caused by a myocardial bridge treated with intracoronary stenting

Myocardial bridges: A review

Much has been written regarding the potential clinical significance of myocardial bridges. As such bridging is often seen in normal individuals, it is clear that not all arteries bridged by myocardial segments produce clinical symptoms thereby suggesting that this feature may simply be an anatomical variant. However, some authors who have considered these bridges as the cause of cardiac ischemia have suggested two potential mechanisms for their pathophysiology. The first is a phasic systolic compression of the bridged segment with persistent mid-to-late diastolic reduction in arterial diameter and the second proposes a reduction in arterial flow. Both mechanisms may contribute to a reduced reserve in coronary blood flow. In this review, we discuss the evidence that exists regarding myocardial bridging and the potential for bridging to cause myocardial ischemia.

Myocardial infarction with distal embolization associated with myocardial bridging in a postoperative patient: a case report

Myocardial bridging is associated with myocardial infarction (MI) on rare occasions. The mechanism by which this occurs is unclear; vessel occlusion in this setting may be due to superimposed thrombosis or vasospasm. An unusual case is presented of postoperative MI from thrombosis associated with myocardial bridging and intravascular volume depletion, with subsequent distal embolization. Endothelial injury as a result of myocardial bridging may predispose to thrombus formation. To avoid MI, adequate fluid hydration is recommended during the perioperative period in patients with myocardial bridging.

Self-expanding intracoronary stent for symptomatic myocardial bridging

Myocardial bridging has been recognized as a potential cause of symptoms of angina, arrhythmias and even infarction. Various treatment strategies including beta-blockers, surgery and more recently intra-coronary stents have been used to manage bridging. We report a novel case of use of self-expanding stent for myocardial bridging in a patient with symptoms of angina and ischemia on nuclear imaging. We further present the 18-month follow up showing minimal in-stent stenosis. To our knowledge, this is the first report of using a self-expanding stent in myocardial bridging. The use of self-expanding stents could be a potential treatment for symptomatic myocardial bridging.

The relationship of myocardial bridges to coronary artery dominance in the adult human heart

Myocardial bridging is recognized as an anatomical variation of the human coronary circulation in which an epicardial artery lies in the myocardium for part of its course. Thus, the vessel is 'bridged' by myocardium. The anterior interventricular branch of the left coronary artery has been reported as the most common site of myocardial bridges but other locations have been reported. The purpose of this study was to provide more definitive information on the vessels with myocardial bridges, the length and depth of the bridged segment, and the relationship between the presence of bridges and coronary dominance. Two hundred formalin-fixed human hearts were examined. Myocardial bridges were found in 69 (34.5%) of the hearts with a total of 81 bridges. One bridge was found in 59 of these hearts and multiple bridges were observed in ten (eight with double bridges and two with triple bridges). Bridges were most often found over the anterior interventricular artery (35 hearts). Bridges were also found over the diagonal branch of the left coronary artery (14), over the left marginal branch (five) and over the inferior interventricular branch of the left coronary artery (six). Bridges were also found over the right coronary artery (15 hearts), over the right marginal branch (four) and over the inferior interventricular branch of the right coronary artery (two). The presence of bridges appeared to be related to coronary dominance, especially in the left coronary circulation. Forty-six (66.6%) of the hearts with bridges were left dominant. Forty-two of these had bridges over the left coronary circulation and four over the right coronary circulation. Seventeen hearts (24.6%) were right dominant. Eleven of these had bridges over the right coronary circulation and six over the left coronary circulation. The remaining six hearts were co-dominant with four having bridges over the left coronary circulation and two over the right coronary circulation. The mean length of the bridges was 31 mm and the mean depth was 12 mm. The possible clinical implications of myocardial bridging may vary from protection against atherosclerosis to systolic vessel compression and resultant myocardial ischaemia.

Detection of myocardial bridging with ECG-gated MDCT and multiplanar reconstruction

OBJECTIVE

The aim of this study was to evaluate the incidence of myocardial bridging in 626 patients examined with MDCT angiography of the coronary arteries.

MATERIALS AND METHODS

Six hundred twenty-six patients who were referred to Florence Nightingale and Atatürk University Hospitals were involved in this study. These patients had atypical chest pain, symptoms suggestive of coronary artery disease, or no significant cardiac complaint. Patients were in sinus rhythm and were premedicated with metoprolol tartrate (5 mg/mL IV bolus) to decrease the heart rate and nitroglycerin (5 mg sublingual 1 min before the examination) to dilate the coronary arteries. MDCT was performed on two different 16-MDCT scanners.

RESULTS

Among the 626 patients, 22 cases (3.5%) of myocardial bridging were detected. Fifteen cases of myocardial bridging (2.4%) were located at the middle third of the left anterior descending coronary artery (LAD), five (0.8%) were at the distal third of the LAD, and two (0.3%) were at the proximal third of the LAD. In these patients, the length of tunneled artery was between 6 and 22 mm, with a mean of 17 mm, and the depth of tunneled artery was between 1.2 and 3.3 mm, with a mean of 2.5 mm.

CONCLUSION

We found the incidence of myocardial bridging in this patient group to be 3.5%. This result is in agreement with some of the angiographic studies in the literature. Our study showed that MDCT is a reliable and noninvasive tool for diagnosing coronary myocardial bridging. After evaluating resource axial images, it is necessary to also evaluate the sagittal multiplanar reconstruction images for myocardial bridging.

Diastolic coronary artery compression in a cardiac transplant recipient: Treatment with a stent

Myocardial bridges, with resultant systolic compression of the coronary artery, are common inborn anomalies that generally have a benign course. Diastolic compression of the coronary artery, however, is a rare finding that is believed to be an acquired lesion. It can be hypothesized that during diastole, when left ventricular filling occurs, the coronary artery is compressed against epicardial scar tissue or a noncompliant pericardium. This can then lead to diminished intracoronary blood flow. We present a case of functionally significant diastolic coronary artery compression in a cardiac transplant recipient who was successfully treated with intracoronary stent placement.

Myocardial Bridging

An epicardial segment of a coronary artery that courses through the myocardium is termed "myocardial bridging". Generally, this is a benign condition but it may lead to angina, ischemia or infarction. The current diagnostic standard of reference is coronary catheter angiography. Intravascular ultrasound (IVUS) and intracoronary Doppler (ICD) have been recently introduced as well. These are all invasive imaging modalities. We describe the utilization of gated multidetector CT (MDCT) as a non-invasive alternative for diagnosis of this anomaly. Information regarding the tunneled coronary artery including its length, depth, precise location and surrounding myocardium is easily obtainable.

Coronary stenting for a muscular bridge in a patient with hypertrophic obstructive cardiomyopathy

A young woman with hypertrophic cardiomyopathy presented with intractable chest pain due to a myocardial bridge over the left anterior descending artery, producing severe compression during systole. Percutaneous intracoronary stenting was performed. The patient, however, developed severe and diffuse restenosis within 30 days of the procedure. Myotomy may provide a more effective treatment option for such patients with symptomatic myocardial bridging.

Importance of diastolic fractional flow reserve and dobutamine challenge in physiologic assessment of myocardial bridging

OBJECTIVES

This study reports a comparative assessment of the hemodynamic relevance of myocardial bridges (MB) using two modalities of fractional flow reserve (FFR), with and without concomitant inotropic challenge.

BACKGROUND

Extravascular coronary compression by means of MB is modulated by myocardial inotropism and causes intracoronary systolic pressure overshooting and negative systolic gradients across the MB. The former characteristic suggests that adequate hemodynamic assessment of MB should include inotropic stimulation. The latter characteristic might interfere with FFR by decreasing the mean pressure gradient.

METHODS

We compared the hemodynamic relevance of 12 lone MB in symptomatic patients using conventional (mean) and diastolic FFR. Diastolic FFR was obtained from post-processed, digitally acquired electrocardiogram and pressure signals. Previously validated cut off values of 0.75 (mean FFR) and 0.76 (diastolic FFR) for hemodynamic relevance were used. Measurements were performed at baseline and after incremental intravenous dobutamine doses.

RESULTS

Fractional flow reserve decreased during dobutamine challenge: mean FFR was 0.90 +/- 0.04 at baseline and 0.84 +/- 0.06 after dobutamine (p = 0.0008); similarly, diastolic FFR was 0.88 +/- 0.05 and 0.77 +/- 0.10 before and after dobutamine, respectively (p = 0.0006). Diastolic FFR identified hemodynamic relevance in five patients, whereas mean FFR did so in only one patient. The discrepancy between mean FFR and diastolic FFR increased with dobutamine challenge: the ratio of mean FFR/diastolic FFR was 1.03 at baseline and 1.09 after dobutamine (p = 0.02). During the administration of dobutamine, the discrepancy was inversely related to the systolic pressure gradient (r = 0.58, P = 0.04).

CONCLUSIONS

Physiologic assessment of MB should include dobutamine challenge. Because the overshooting of systolic pressure interferes with and is a cause of error in FFR measurements based on mean pressures, diastolic FFR appears to be the technique of choice for MB assessment, whereas mean FFR should be used with caution.

Myocardial Bridge: a clinical review

Human coronary arteries occasionally course intramyocardially--a condition termed Myocardial Bridge. We review the anatomic and pathophysiological basis of the Myocardial Bridge and discuss clinical presentations, prognoses and the current treatment options for this interesting coronary angiographic variant.

A stratified approach to the treatment of a symptomatic myocardial bridge

A case of symptomatic myocardial bridge requiring intracoronary stent complicated by in-stent restenosis is reported. A stratified approach for the treatment of a symptomatic myocardial bridge is proposed.

Successful surgical resection of a muscular bridge in a patient with nonobstructive hypertrophic cardiomyopathy--a case report

The authors report a case of myocardial bridging associated with nonobstructive hypertrophic cardiomyopathy and severe intractable chest pain that was relieved by surgical resection of the muscular bridge. Surgical resection of a myocardial bridge may be considered in patients with refractory symptoms that can clearly be attributed to muscular bridge.

Long term angiographic and clinical follow up in patients with stent implantation for symptomatic myocardial bridging

OBJECTIVE

To assess long term results of coronary stent implantation in patients with symptomatic myocardial bridging.

METHODS

Intracoronary stent implantation was performed within the intramural course of the left anterior descending coronary artery in 11 patients with objective signs of myocardial ischaemia and absence of other cardiac disorders. All had myocardial bridging of the central portion of the left anterior descending coronary artery. Quantitative coronary angiography was performed before and after stent deployment, and again at seven weeks and six months. Clinical evaluation was done at two years.

RESULTS

After stent deployment, quantitative coronary angiography showed absence of systolic compression along the left anterior descending coronary artery; the minimum luminal diameter (mean (SD)) increased from 0.6 (0.3) mm before stent implantation to 1.9 (0.3) mm after implantation (p < 0. 05). Intravascular ultrasound showed an increase in cross sectional area from 3.3 (1.3) mm(2) at baseline to 6.8 (0.9) mm(2) (p < 0.005) after stent deployment. Coronary flow reserve was normalised from 2. 6 (0.5) at baseline to 4.0 (0.5) (p < 0.005) after stent implantation. At seven weeks, quantitative coronary angiography showed mild to moderate or severe in-stent stenosis in five of the 11 patients; four of these underwent repeat target vessel revascularisation (percutaneous transluminal coronary angioplasty in two; coronary artery bypass grafting in two). At six months, all patients (n = 9) showed good angiographic results, including those who had target vessel revascularisation. On clinical evaluation at two years, all patients (including those with target vessel revascularisation) remained free of angina and cardiac events.

CONCLUSIONS

Intracoronary stent implantation prevents external compression of bridged coronary artery segments, with increase in luminal diameter and alleviation of symptoms. The incidence of in-stent stenosis requiring target vessel revascularisation (36%) is comparable with that of lesions of 25 mm length in coronary artery disease. The symptom free and event free two year follow up data suggest that stent implantation is a useful way of treating symptomatic patients with myocardial bridges.