Myocardial stunning associated with a myocardial bridge

A chart review on surgical myocardial debridging in symptomatic patients: a safe procedure with good long-term clinical outcome and coronary computed tomographic angiography results

OBJECTIVES

Myocardial bridging is mostly diagnosed as an incidental imaging finding but can result in severe vessel compression and significant clinical adverse complications. Since there is still an ongoing debate when to propose surgical unroofing, we studied a group of patients where this was performed as an isolated procedure.

METHODS

In 16 patients (38.9 ± 15.7 years, 75% men) who had surgical unroofing for symptomatic isolated myocardial bridges of the left anterior descending artery, we retrospectively analysed symptomatology, medication, imaging modalities used, operative techniques, complications and long-term outcome. Computed tomographic fractional flow reserve was calculated to understand its potential value for decision-making.

RESULTS

Most procedures were performed on-pump (75%, mean cardiopulmonary bypass 56.5 ± 27.9 min, mean aortic cross-clamping 36.4 ± 19.7 min). Three patients needed a left internal mammary artery bypass since the artery dived inside the ventricle. There were no major complications or deaths. The mean follow-up was 5.5 years. Although there was a dramatic improvement in symptoms, still 31% experienced atypical chest pain at various moments during follow-up. Postoperative radiological control was performed in 88%, showing no residual compression or recurrent myocardial bridge and patent bypass if performed. All postoperative computed tomographic flow calculations (7) showed a normalization of coronary flow.

CONCLUSIONS

Surgical unroofing for symptomatic isolated myocardial bridging is a safe procedure. Patient selection remains difficult but introducing standard coronary computed tomographic angiography with flow calculations could be helpful in preoperative decision-making and during follow-up.

Use of Novel Blunt Dissection Technique for Surgical Unroofing in Myocardial Bridging Patients

Background

Myocardial bridging (MB) is a congenital anomaly involving the myocardial tissue encasement of a segment of the coronary artery. The purpose of the present study was to assess safety and efficacy of two surgical methods used for treating MB patients at our institute.

Methods

Off-pump MB unroofing was performed in 45 adult patients between January 2016 and December 2021 by traditional surgical unroofing techniques (conventional group, n = 26) and blunt dissection techniques (blunt dissection group, n = 19). We retrospectively reviewed our patients by examining the baseline clinical characteristics, risk factors, medications, and diagnostic data for coronary artery disease. The Seattle Angina Questionnaire (SAQ) was used to assess angina symptoms both preoperatively and 6 months postsurgery.

Results

No significant difference in preoperative clinical characteristics was observed between the two groups. The blunt dissection group had shorter unroofed period (14.69 vs. 18.91 mins, P=0.001), less ventilator time (16.26 vs. 24.62 hours, P < 0.001), and a shorter hospital stay (8.74 vs. 12.89 days, P < 0.001). Although both traditional and blunt dissection techniques significantly improved postoperative SAQ scores including physical limitation due to angina, anginal stability, anginal frequency, treatment satisfaction, and quality of life (P < 0.001), no significant difference was observed between the traditional and blunt dissection techniques for SAQ. No cases of left anterior descending (LAD) injury in the blunt dissection group were observed although seven patients in the conventional group had LAD injuries.

Conclusions

In our single-center experience of MB unroofing, the blunt dissection technique is a safe, effective technique that significantly reduces surgical and ventilator time and hospital stay. MB patients with severe angina who underwent the blunt dissection for surgical unroofing experienced significant improvements in anginal symptoms and quality of life six months after the surgery.

Therapeutic Dilemmas Faced When Managing a Life-Threatening Presentation of a Myocardial Bridge

Background. Myocardial bridges are congenital abnormalities, where a segment of coronary artery travels intramyocardially, rather than the typical epicardial course. The overlying muscle segment is termed “the bridge”. Most myocardial bridges are asymptomatic, but some can result in myocardial ischaemia, arrhythmias, and sudden cardiac death. Case Presentation. A 31-year-old male with no past medical history presented to our tertiary cardiac centre following an out-of-hospital ventricular fibrillation arrest. Coronary angiography and computed tomography of the coronary arteries revealed a 2 cm myocardial bridge overlying the left anterior descending (LAD) artery. An exercise echocardiogram demonstrated severe apical ballooning and hypokinesis during peak exercise, with corresponding ST-segment elevation, resolving on rest. Options for medical therapy of a symptomatic myocardial bridge include beta blockers, calcium channel blockers, ivabradine, or a combination thereof. Surgical interventions include deroofing the bridge and revascularisation of the affected region with bypass grafting. However, a lack of trial data comparing medical regimens and surgical interventions makes it difficult to ascertain the most effective management strategy for each patient. There was disagreement between experts at different tertiary centres over the optimal management of this patient. He was treated with multiple regimes of medical therapy with ongoing ischaemia on stress testing, before undergoing a negative stress test on amlodipine, diltiazem, and isosorbide mononitrate. It was felt that no further intervention was necessary at this time given his exercise test was now negative for ischaemia. However, after seeking a second opinion, he underwent surgical intervention with bypass grafting of his left anterior descending artery, followed by implantation of an implantable cardiac defibrillator. Subsequently, an angiogram postsurgery demonstrated concomitant spasm of the LAD and he was resumed on medical therapy with calcium channel blockers and nitrates. Discussion. Without randomised trials, it is impossible to determine the optimal management strategy for each patient. It is possible that some patients with myocardial bridges are not being trialled on optimal medical therapy prior to undergoing invasive and irreversible interventions.

Morphological analysis of myocardial bridges and coronary arterial dominance in northeast Brazil

BACKGROUND

Coronary arterial dominance and myocardial bridges have clinical implications, since a left dominant pattern associated to the presence of myocardial bridges is often associated to a higher incidence of arteriosclerosis and higher mortality by myocardial infarction.

OBJECTIVE

To determine the presence and position of myocardial bridges and their relation with coronary arterial dominance.

METHODS

Fifty-seven human cadaveric hearts were analyzed into three groups, as follows: right dominance; left dominance; codominance. Each group was then divided into two subgroups: with or without myocardial bridges. Finally, each subgroup with myocardial bridges was classified according to the position of the myocardial bridge according to the main axis of the heart (proximal, middle and distal third).

RESULTS

The right dominance occurred in most hearts (30 hearts-52,6%). Twenty-three myocardial bridges (40,3%) were identified and mostly occurred on left dominant hearts (22,8%). The pattern of coronary dominance presented a statistically significant correlation with the presence of myocardial bridges (P=0.048). The middle third of the heart axis showed the highest occurrence of myocardial bridges.

CONCLUSION

These findings suggest there is a clear relationship between the presence of myocardial bridges and left dominant pattern. Middle third of the heart axis present the higher occurrence of myocardial bridges. Knowledge of the myocardial bridges morphology is of great clinical significance, improving patient care.

Bridging the Gap in a Rare Cause of Angina

Myocardial bridging occurs when coronary arteries run intramurally. Episodes of tachycardia can cause a dynamic obstruction that extends into diastole, compromising coronary filling time, and subsequently leading to ischaemia. Myocardial ischaemia, acute coronary syndrome, coronary spasm, myocardial stunning, arrhythmia, takotsubo cardiomyopathy, and sudden cardiac death have all been reported with bridging. Atherosclerotic plaques develop proximally in the bridge due to low shear stress and high oscillatory wall-flow. Factors affecting atherosclerotic build-up include disrupted flow patterns (particularly flow recirculation, which exacerbates LDL internalisation), cell adhesion and monocyte adhesion to the endothelium. Endothelial health depends on arterial flow patterns, given that the vessel reacts differently to various flow types, as confirmed in 3D simulations. Medication is the first-line therapy, while surgical de-roofing and coronary bypass are reserved for severe stenosis. Distinguishing physiological arterial compression from pathological stenosis is essential. Deeper bridges correlating with recurrent angina with an instantaneous wave-free ratio ≤0.89 or fractional flow reserve ≤0.80 are treated.

Surgical treatment of symptomatic left anterior descending myocardial bridges: myotomy vs. bypass surgery

PURPOSE

To compare the effects of myotomy and bypass surgery for treating myocardial bridges (MBs) over the left anterior descending artery (LAD) in a single-center observation study.

METHODS

Fifty-four eligible patients (34 males, median age of 60 years old) with symptomatic LAD-MBs who underwent myotomy (31 patients) or bypass surgery (23 patients) were included in this study. The primary endpoints were the occurrence of major adverse cardiac events (MACEs) and angiographic demonstration of adverse angiographic results.

RESULTS

No surgical death was observed. During a median follow-up of 26 months, 11 patients developed MACEs (7.4% for myotomy vs. 40.9% for bypass surgery, p = 0.007). Surgical strategy (bypass surgery vs. myotomy) was an independent risk factor for MACEs (odds ratio = 3.681, 95% confidence interval 1.814-8.685, p = 0.011). Myotomy compared with bypass surgery had a significantly lower incidence of adverse angiographic results (3.7% of residual compression vs. 40.9% of LIMA graft failure, p = 0.003). Among ten patients suffering from LAD-MBs with concomitant proximal coronary stenosis who underwent bypass surgery, only one reported transient recurrent exertional chest pain, and all LIMA grafts were patent.

CONCLUSIONS

Myotomy of symptomatic LAD-MBs may be associated with encouraging midterm results. Bypass surgery may be recommended for treating symptomatic LAD-MBs with concomitant proximal coronary stenosis.

Extensive unroofing of myocardial bridge: A case report and literature review

Background:

Myocardial bridge is defined as a segment of a coronary artery that takes an intramyocardial course. The presence of myocardial bridge has been observed in as many as 40%–80% of cases on autopsy, angiographically from 0.5% to 16.0%, and often asymptomatic. However, it has been associated with angina, coronary spasm, myocardial infarction, arrhythmias, syncope, sudden cardiac arrest, and death. Conflicting opinions exist on the timing of surgical intervention for myocardial bridge.

Methods:

We present an unusual case of a young female, with prior aortic surgery, who had refractory chest pain despite optimal medical therapy. Stress testing revealed anterior ischemia. Cardiac catherization showed myocardial bridge of the left anterior descending artery with significant compromise of blood flow (fractional flow reserve = 0.75 with adenosine). We proceeded with surgery. Intraoperatively, we found an unusually long (10-cm) intramyocardial segment of the left anterior descending artery which was managed by surgically unroofing. Our patient felt better post procedure. Repeat cardiac catheterization showed no further narrowing of the left anterior descending artery with a fractional flow reserve of 0.87 in its distal segment.

Results/discussion:

Myocardial bridge is present mostly in female patients (74.5%), with median age at 56.2 years and mostly involving the left anterior descending artery (77.2%). The average length of myocardial bridge is 21.85 ± 16.10 mm (range: 5–70 mm). Our case is unique as the involved myocardial bridge was 10 cm in length, the longest ever reported. Multiple imaging modality revealed significant coronary insufficiency, with a subsequent clinical and angiographic improvement upon unroofing of the culprit coronary vessel.

Conclusion:

Management decision on myocardial bridge remains controversial. This is a case of the longest symptomatic myocardial bridge, with a subsequent improvement post unroofing.

Multiple myocardial bridges associated with left-ventricular dysfunction, intermittent left bundle branch block, and cardiac memory: A case report

Myocardial bridges are a congenital anomaly in which a segment of the coronary artery takes a "tunneled" intramuscular course. Few reports have associated myocardial bridges with left-ventricular dysfunction in patients with ischemia. Intermittent left bundle branch block is a conduction disturbance that has been described to be associated with myocardial bridges and cardiac memory. This study reports unusual associations of multiple myocardial bridges, angina, left-ventricular dysfunction, intermittent left bundle branch block, and cardiac memory.

Three-vessel myocardial bridging: A possible cause of myocardial stunning

The authors report a rare clinical case of myocardial bridging of the three major coronary arteries, which manifested in an unusual way with severe biventricular dysfunction in the context of tachycardia. For the diagnosis, the authors relied on non-invasive multimodality cardiac imaging, including cardiac magnetic resonance, computed tomography angiography and myocardial perfusion scintigraphy. The implementation of targeted medical and neurohormonal therapy resulted in the recovery of ventricular function and clinical improvement.

Surgical unroofing of hemodynamically significant myocardial bridges in a pediatric population

BACKGROUND

Although myocardial bridges (MBs) are traditionally regarded as incidental findings, it has been reported that adult patients with symptomatic MBs refractory to medical therapy benefit from unroofing. However, there is limited literature in the pediatric population. The aim of our study was to evaluate the indications and outcomes for unroofing in pediatric patients.

METHODS

We retrospectively reviewed all pediatric patients with MB in our institution who underwent surgical relief. Clinical characteristics, relevant diagnostic data, intraoperative findings, and postoperative outcomes were evaluated.

RESULTS

Between 2012 and 2016, 14 pediatric patients underwent surgical unroofing of left anterior descending artery MBs. Thirteen patients had anginal symptoms refractory to medical therapy, and 1 patient was asymptomatic until experiencing aborted sudden cardiac arrest during exercise. Thirteen patients underwent exercise stress echocardiography, all of which showed mid-septal dys-synergy. Coronary computed tomography imaging confirmed the presence of MBs in all patients. Intravascular ultrasound imaging confirmed the length of MBs: 28.2 ± 16.3 mm, halo thickness: 0.59 ± 0.24 mm, and compression of left anterior descending artery at resting heart rate: 33.0 ± 11.6%. Invasive hemodynamic assessment with dobutamine confirmed the physiologic significance of the MBs with diastolic fractional flow reserve: 0.59 ± 0.13. Unroofing was performed with the patient under cardiopulmonary bypass (CPB) in the initial 9 cases and without CPB in the subsequent 5 cases. All patients were discharged without complications. The 13 symptomatic patients reported resolution of symptoms on follow-up, and improvement in symptoms and quality of life was documented using the Seattle Angina Questionnaire version 7.

CONCLUSIONS

Unroofing of MBs can be safely performed in pediatric patients, with or without use of CPB. In symptomatic patients, unroofing can provide relief of symptoms refractory to medical therapy.

Current interpretation of myocardial stunning

Myocardial stunning is a temporary post-ischemic cardiac mechanical dysfunction. As such, it is a heterogeneous entity and different conditions can promote its occurrence. Transient coronary occlusion, increased production of catecholamines and endothelin, and myocardial inflammation are all possible causes of myocardial stunning. Possible underlying mechanisms include an oxyradical hypothesis, calcium overload, decreased responsiveness of myofilaments to calcium, and excitation-contraction uncoupling due to sarcoplasmic reticulum dysfunction. The aim of this review is to summarize the clinical conditions that may be responsible for stunned myocardium.

Assessment of indirect inflammatory markers in patients with myocardial bridging

Introduction:

Myocardial bridging (MB) is a congenital variant of the coronary artery in which a portion of the epicardial coronary artery takes an intramuscular course. Although it is considered a benign anomaly, it may lead to such complications as myocardial ischaemia, acute coronary syndrome, coronary spasm, exercise-induced dysrhythmias or even sudden death. MB may be related to increased inflammatory and atherosclerotic processes. This study was conducted with the aim of evaluating the relationship between neutrophil/ lymphocyte ratio (NLR) and MB.

Methods:

Taking into consideration the inclusion criteria, 86 patients with MB and 88 with normal coronary angiographies (control group) were included in the study. The association between MB and laboratory and other clinical parameters was evaluated.

Results:

The platelet distribution width (PDW) (17.3 ± 0.40 vs 16.1 ± 0 .5; p < 0.05), NLR (3.2 ± 1.3 vs 2.2 ± 0.9; p < 0.05) and red cell distribution width (RDW) (14.3 ± 1.3 vs 13.1 ± 1.1; p < 0.05) were significantly higher in the MB group than in the control group.

Conclusions:

This study demonstrated that compared to normal coronary arteries, PDW, NLR and RDW were significantly higher in MB patients. Further studies are needed to clarify the increased inflammatory parameters in patients with MB.

Myocardial bridging: contemporary understanding of pathophysiology with implications for diagnostic and therapeutic strategies

Patients with myocardial bridging are often asymptomatic, but this anomaly may be associated with exertional angina, acute coronary syndromes, cardiac arrhythmias, syncope, or even sudden cardiac death. This review presents our understanding of the pathophysiology of myocardial bridging and describes prevailing diagnostic modalities and therapeutic options for this challenging clinical entity.

Results of coronary artery bypass grafting in myocardial bridging of left anterior descending artery

BACKGROUND

We aimed to evaluate the graft patency rate following coronary artery bypass grafting (CABG) to the left anterior descending artery (LAD) with proximal myocardial bridging (MB). While MB is generally a benign coronary abnormality, ischemia, stunning, and sudden death have been reported. In symptomatic patients with proximal LAD systolic compression of >50%, positive for ischemic noninvasive testing and noneffective optimal medical therapy, coronary intervention could be indicated. Few studies of CABG in myocardial bridging have been reported. The influence of high flow in coronaries with MB on graft patency is cause for concern.

METHODS

We retrospectively studied 39 patients operated on for isolated MB of proximal LAD with >50% systolic compression. All patients were severely symptomatic despite optimal medical therapy and positive noninvasive tests for myocardial ischemia. CABG was performed through the midsternotomy with cardiopulmonary bypass and cardioplegia. Patients were divided into two groups: in 20 patients, LAD was bypassed with left internal mammary artery (LIMA) (Group 1) and in 19 patients with saphenous vein graft (SVG) (Group 2). All patients underwent follow-up coronary angiography.

RESULTS

Demographics and degree of systolic compression of the LAD were similar in both groups. There was no mortality or major morbidity. Freedom from angina was 68% in Group 1 and 94% in Group 2 at 18 months postoperatively (p = 0.58). Twelve LIMA grafts and three SVGs were found occluded (p = 0.002).

CONCLUSIONS

LIMA patency in myocardial bridging of the LAD can be low. SVGs should be considered in cases of CABG for myocardial bridging.

Takotsubo cardiomyopathy--a clinical review

Stress cardiomyopathy is characterised by reversible left ventricular dysfunction. It simulates an acute coronary syndrome (ACS), presenting with precordial pain or dyspnoea, changes of the ST segment, T wave, or QTc interval on electrocardiogram, and raised cardiac enzymes. Typical findings are disturbances of segmental contractility (apical hypokinesia or akinesia), with normal epicardial coronary arteries. The true prevalence is unknown, as the syndrome may be under-diagnosed; it is more common in postmenopausal women. There is usually a trigger in the form of physical or psychological stress. The electrocardiographic, echocardiographic, and ventriculographic changes resolve spontaneously over a variable period of time (from days to months). There are a number of pathophysiological theories, none of which has been shown to be definitive, suggesting that all of them may be involved to some extent. The prognosis is generally favourable, and recurrence is very rare.

Myocardial bridging in absence of coronary artery disease: proposal of a new classification based on clinical-angiographic data and long-term follow-up

BACKGROUND

There is no widely accepted classification to guide therapy in patients with symptomatic myocardial bridging (MB).

METHODS

A retrospective analysis of 157 patients with chest pain, angiographic MB of the left anterior descending artery without obstructive coronary artery disease (CAD) was performed. Patients were evaluated for clinical symptoms, objective signs of ischemia by stress test, intracoronary Doppler flow measurement and coronary flow reserve. 100 patients without CAD or MB served as controls.

RESULTS

There was no difference in clinical symptoms and objective signs of ischemia between controls and patients with MB. The length of MB was 22.6 +/- 7.8 mm, maximal systolic luminal diameter reduction 71 +/- 16%, and maximal mid-diastolic luminal reduction 34.7 +/- 13% as demonstrated by quantitative coronary angiography (QCA). Intracoronary Doppler showed significantly increased average peak flow velocity (APV), average systolic peak velocity (ASPV), average diastolic peak flow velocity (ADPV), and maximal peak velocity (MPV) in MB versus proximal and distal segments at rest and after maximal vasodilatation (p < 0.001 for all parameters). Coronary flow reserve was significantly higher proximally (2.9 +/- 0.9) compared with segments distal to the MB (2.0 +/- 0.6, p < 0.01). We propose a new MB classification for symptomatic patients with MB:Type A:incidental finding on angiography, no objective signs of ischemia; Type B: objective signs of ischemia, and Type C: with or without objective signs of ischemia and altered intracoronary hemodynamics (by QCA/CFR/intracoronary Doppler). 5-Year follow-up data based on this classification showed that types B and C responded well to beta-blockers or calcium channel antagonists. Patients with type C refractory to medical therapy were treated with stenting of the MB.

CONCLUSION

Patients with MB without CAD did not have a higher prevalence of chest pain or abnormal non-invasive stress tests compared to patients without CAD or MB. Intracoronary hemodynamic measurement is a novel approach that may be valuable in defining the functional significance of MB. We propose a classification of symptomatic patients with MB without CAD using non-invasive and invasive parameters to guide therapeutic choices.

Myocardial bridging as evaluated by 16 row MDCT

PURPOSE

The purpose of this study is to find out the prevalence, appearance and clinical symptoms of myocardial bridging (MB) by MDCT coronary angiography (CTA).

MATERIALS AND METHODS

A total of 280 (50 females) consecutive patients followed with coronary artery disease or postoperative stent and bypass control, underwent CTA performed by 16-MDCT scanner between January 2006 and April 2006. Short axis multiplanar reformatted images were evaluated. MBs were classified as complete and incomplete bridges with respect to continuity of the myocardium over the tunneled segment of left anterior descending artery (LAD) in interventricular groove and the cut-off value is 1.3mm. Patients diagnosed with MB on CTA who had prior catheter angiography studies were re-evaluated for the presence of MB.

RESULTS

One hundred and twenty MBs [98 (81.6%) on LAD, 2 (1.6%) on diagonal branch, 11 (9.1%) on obtuse marginal, 4 (3.3%) on right coronary artery, 5 (4.1%) on ramus intermedius artery] were detected in 108 (38.5%) patients. Eighty-five (70.8%) of bridged segments in 79 (28.2%) patients were complete and the rest [35 (29.2%) in 34 (12.1%) patients] were incomplete. In 12 patients two MBs (either on different arteries or on the same artery) were detected. The length of bridged segments in patients with complete and incomplete MBs varied between 4-50.9mm (mean 18mm) and 4-37.3mm (mean 13.6mm), respectively, and the depth of myocardium over the artery ranged between 1-6.4mm (mean 2.3mm) and 1-1.2mm (mean 1mm), respectively. Thirty (27.7%) out of 108 patients, in whom MB was detected on CTA, were found to have correlative catheter angiography studies, retrospectively and MB was detected only in 4 (13.3%) out of 30 patients.

CONCLUSION

MDCT coronary angiography is a non-invasive, efficient method in the diagnosis of MB avoiding the procedural risks that catheter angiography carries. MDCT coronary angiography allows direct visualization of the bridge itself and may thus give the opportunity to differentiate between complete and incomplete myocardial bridges.

Myocardial bridging

Myocardial bridging, a congenital coronary anomaly, is a clinical condition with several possible manifestations, and its clinical relevance is debated. This article reviews current knowledge about the anatomy, pathophysiology, clinical relevance, and treatment of myocardial bridging. Myocardial bridging is present when a segment of a major epicardial coronary artery, the 'tunnelled artery', runs intramurally through the myocardium. With each systole, the coronary artery is compressed. Myocardial bridging has been associated with angina, arrhythmia, depressed left ventricular function, myocardial stunning, early death after cardiac transplantation, and sudden death. Evidence indicates that the intima beneath the bridge is protected from atherosclerosis, and the proximal segment is more susceptible to development of atherosclerotic lesions because of haemodynamic disturbances. New techniques (e.g. intravascular ultrasonography and intracoronary Doppler studies) have revealed new characteristics and pathophysiologic processes such as diastolic flow abnormalities. Medical treatment generally includes beta-blockers. Nitrates should be avoided because symptoms may worsen. Intracoronary stents and surgery have been attempted in selected patients. Additional research is needed to define patients in whom myocardial bridging is potentially pathologic, and randomized multicentre long-term follow-up studies are needed to assess the natural history, patient selection, and therapeutic approaches.