Myocardial Bridge: The Hidden Culprit Behind Chest Pain and Hypertension

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 Myocardial Bridge: The Hidden Culprit Behind Chest Pain and Hypertension

In the intricate anatomy of the human heart, coronary arteries play a pivotal role in supplying oxygen-rich blood to the myocardium. However, in some individuals, a congenital anomaly known as a myocardial bridge (MB) can alter this delicate balance, leading to potential cardiovascular complications.

Understanding Myocardial Bridge

A myocardial bridge occurs when a segment of a coronary artery, most commonly the left anterior descending (LAD) artery, tunnels through the myocardium instead of resting on its surface. During systole, the heart muscle contracts, compressing the bridged artery and potentially impeding blood flow. This compression can lead to myocardial ischemia, manifesting as chest pain or even more severe cardiac events in certain cases.

Prevalence and Clinical Significance

The prevalence of myocardial bridging varies, with studies indicating occurrences in approximately 15% to 25% of the population. Despite its relative commonality, many individuals with MB remain asymptomatic, and the condition is often considered benign. However, in symptomatic cases, MB has been associated with conditions such as myocardial infarction with non-obstructive coronary arteries (MINOCA), arrhythmias, and sudden cardiac death. 

Pathophysiology: Beyond Simple Compression

While the mechanical compression of the artery during systole is a hallmark of MB, recent studies have unveiled more complex pathophysiological mechanisms. These include:

  • Endothelial Dysfunction: Impaired endothelial function within the bridged segment can exacerbate ischemia.

  • Delayed Diastolic Relaxation: A delay in the relaxation of the bridged artery during diastole can prolong the period of compression.

  • Vasospasm: Increased sympathetic tone can lead to vasospasm in the bridged segment, further compromising blood flow.

  • Atherosclerotic Plaque Disruption: Mechanical stress on the artery can lead to plaque rupture or erosion, thereby increasing the risk of acute coronary events.

These mechanisms underscore the need for a comprehensive understanding of MB's pathophysiology to guide effective management strategies. 

Diagnostic Approaches

Accurate diagnosis of myocardial bridging requires a combination of imaging modalities:

  • Coronary Computed Tomography Angiography (CTA): Provides detailed visualization of the coronary anatomy, identifying the presence and extent of the myocardial bridge.

  • Intravascular Ultrasound (IVUS): Offers real-time imaging of the coronary artery, assessing the degree of compression and the length of the bridged segment.


  • Fractional Flow Reserve (FFR): Measures the pressure differences across the bridged segment to assess its functional significance.


Association between myocardial bridge grade, stress diastolic fractional flow reserve (FFR), and computed tomography-derived FFR. A grade 3 myocardial bridge as demonstrated in axial and multiplanar reconstruction views (A and C). Diastolic FFR in this case was 0.54. However, computed tomography-derived FFR was 0.88 as demonstrated in B. https://doi.org/10.1161/CIRCIMAGING.119.009576

  • Stress Echocardiography: Evaluates myocardial function under stress, identifying areas of ischemia associated with the myocardial bridge.

These diagnostic tools are essential in differentiating between incidental findings and clinically significant myocardial bridging. 

Management Strategies

The management of myocardial bridging is tailored to the individual's symptoms and the severity of the condition:

  • Medical Therapy: Beta-blockers are commonly used to reduce heart rate and myocardial oxygen demand, alleviating symptoms. Calcium channel blockers may be considered in cases with vasospasm. Nitrates are generally avoided due to their potential to exacerbate ischemic heart disease.

  • Surgical Intervention: In cases where medical therapy is ineffective, surgical options such as unroofing (myotomy) may be considered to relieve arterial compression. This procedure involves removing the myocardial tissue overlying the bridged artery, restoring normal blood flow. 

  • Lifestyle Modifications: Patients are advised to adopt heart-healthy lifestyles, including regular exercise, a balanced diet, and smoking cessation, to mitigate the risk of atherosclerosis and other cardiovascular diseases.

Prognosis and Long-Term Outlook

The prognosis for individuals with myocardial bridging is generally favorable, especially in asymptomatic cases. However, regular follow-up is recommended to monitor for the development of symptoms or complications. In symptomatic individuals, appropriate medical or surgical interventions can significantly improve outcomes. Early detection and personalized management are key to preventing adverse cardiovascular events.

Conclusion

Myocardial bridging is a congenital coronary anomaly that, while often benign, can lead to significant cardiovascular issues in certain individuals. A thorough understanding of its pathophysiology, accurate diagnostic evaluation, and tailored management strategies are essential for optimizing patient outcomes. As research continues to evolve, a more nuanced approach to myocardial bridging will enhance our ability to identify and treat this condition effectively.

Reference

  1. Corban, M. T., Hung, O. Y., Eshtehardi, P., Rasoul-Arzrumly, E., McDaniel, M., Mekonnen, G., ... & Samady, H. (2014). Myocardial bridging: contemporary understanding of pathophysiology with implications for diagnostic and therapeutic strategies. Journal of the American College of Cardiology, 63(22), 2346–2355. https://doi.org/10.1016/j.jacc.2014.01.049

  2. Möhlenkamp, S., Hort, W., Ge, J., & Erbel, R. (2002). Update on myocardial bridging. Circulation, 106(20), 2616–2622. https://doi.org/10.1161/01.CIR.0000038824.20684.46

  3. Tarantini, G., Migliore, F., Cademartiri, F., & Fraccaro, C. (2016). Left anterior descending artery myocardial bridging: a clinical approach. Journal of the American College of Cardiology: Cardiovascular Interventions, 9(9), 887–897. https://doi.org/10.1016/j.jcin.2016.03.008

  4. Kim, P. J., Hur, G., Kim, S. Y., Namgung, J., Hong, S. W., Kim, Y. H., ... & Koo, B. K. (2009). Frequency of myocardial bridging and its relation to coronary artery disease in a Korean population: A multislice CT coronary angiographic study. Korean Circulation Journal, 39(6), 219–223. https://doi.org/10.4070/kcj.2009.39.6.219

  5. Alegria, J. R., Herrmann, J., Holmes, D. R., Lerman, A., & Rihal, C. S. (2005). Myocardial bridging. European Heart Journal, 26(12), 1159–1168. https://doi.org/10.1093/eurheartj/ehi203

  6. Lee, M. S., Chen, C. H., & Shlofmitz, R. A. (2020). Current management and future directions of myocardial bridging. Journal of Clinical Medicine, 9(12), 3853. https://doi.org/10.3390/jcm9123853


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