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

Coronary Artery Anomalies - State of the Art Review

Coronary artery anomalies (CAAs) comprise a wide spectrum of anatomic entities, with diverse clinical phenotypes. We present a case of an anomalous right coronary artery arising from the left aortic sinus with an interarterial course, a potentially fatal condition that can precipitate ischemia and sudden cardiac death. CAAs are increasingly detected in adults, mostly as incidental findings in the course of cardiac evaluation. This is due to the expanding use of invasive and noninvasive cardiac imaging, usually in the work-up for possible CAD. The prognostic implications of CAAs in this group of patients remain unclear. In AAOCA patients, appropriate work-up with anatomical and functional imaging should be performed for risk stratification. An individualized approach to management should be adopted, considering symptoms, age, sporting activities and the presence of high-risk anatomical features and physiologic consequences (such as ischemia, myocardial fibrosis, or cardiac arrhythmias) detected on multimodality imaging or other functional cardiac investigations. This comprehensive and up to date review seeks to crystallize current data in the recent literature, and proposes a clinical management algorithm for the clinician faced with the conundrum of managing such conditions.

Systematic Review and Meta-Analysis of Cardiovascular Consequences of Myocardial Bridging in Hypertrophic Cardiomyopathy

Myocardial bridging (MB) is a congenital variant in which a segment of a coronary artery follows an atypical intramural course under a "bridge" of myocardium and is notably common in hypertrophic cardiomyopathy (HCM). This systematic review and meta-analysis explored the clinical consequences of MB in patients with HCM. A total of 3 outcome domains were investigated: cardiovascular mortality, nonfatal adverse cardiac events, and investigative indicators of myocardial ischemia. A meta-analysis was performed on 10 observational studies comparing outcomes in patients with HCM with and without MB. Studies were identified through a systematic search of 4 databases (PubMed, Scopus, Medline Complete, and Web of Science). The quality of the studies was assessed using a modified version of the Downs and Black tool, from which studies could score a maximum of 23 points. The mean score was 17.5 ± 1.3 (good). The meta-analysis showed that MB was not associated with cardiovascular mortality (odds ratio [OR] 1.70, 95% confidence interval [CI] 0.56 to 5.15, p = 0.35) or nonfatal adverse cardiac events (OR 1.80, 95% CI 0.98 to 3.28, p = 0.06) but was associated with myocardial ischemia (OR 1.89, 95% CI 1.03 to 3.44, p = 0.04). In conclusion, the potential prognostic implications of MB in HCM, especially in those with hemodynamically significant bridges and/or severe underlying disease, should not be ignored. The focus of future studies should be to establish functional and morphologic thresholds, by which MB may adversely influence prognosis by corroborating imaging findings with clinical outcome data.

Coronary artery anomalies evaluation with cardiac computed tomography: A review

Coronary artery anomalies involve either their origin, course, or termination of the vessel. Coronary artery anomalies are congenital and relatively few develop symptoms, which can include potentially serious effects like arrhythmia, chest pain, syncope, myocardial infarction, or sudden death. Conventional coronary angiography has been used extensively in the past few decades for evaluation of coronary anomalies. With recent advancements in the software and hardware, noninvasive nature, and excellent temporal and spatial resolution; coronary computed tomographic angiography (CTA) is now the mainstay in the diagnosis of coronary arterial anomalies. Many studies have shown better performance of cardiac CTA compared to invasive angiography in detection of anomalous coronary arteries.

Update on the Diagnostic Pitfalls of Autopsy and Post-Mortem Genetic Testing in Cardiomyopathies

Inherited cardiomyopathies are frequent causes of sudden cardiac death (SCD), especially in young patients. Despite at the autopsy they usually have distinctive microscopic and/or macroscopic diagnostic features, their phenotypes may be mild or ambiguous, possibly leading to misdiagnoses or missed diagnoses. In this review, the main differential diagnoses of hypertrophic cardiomyopathy (e.g., athlete's heart, idiopathic left ventricular hypertrophy), arrhythmogenic cardiomyopathy (e.g., adipositas cordis, myocarditis) and dilated cardiomyopathy (e.g., acquired forms of dilated cardiomyopathy, left ventricular noncompaction) are discussed. Moreover, the diagnostic issues in SCD victims affected by phenotype-negative hypertrophic cardiomyopathy and the relationship between myocardial bridging and hypertrophic cardiomyopathy are analyzed. Finally, the applications/limits of virtopsy and post-mortem genetic testing in this field are discussed, with particular attention to the issues related to the assessment of the significance of the genetic variants.

Sudden Death and Coronary Artery Anomalies

Congenital coronary artery anomalies (CAA) include a wide spectrum of malformations present at birth with various clinical manifestations and degrees of severity. Patients may be asymptomatic, and CAA may be an incidental finding during cardiac imaging or at autopsy. However, in other cases, ischemia-related signs and symptoms, leading to an increased risk of sudden cardiac death (SCD), often as first presentation may occur. In this chapter, we discuss the normal anatomy of the coronary arteries (CA) and the pathology of CAA at risk of SCD, including our experience with victims of SCD among the young population (age <40 years) and among athletes.

Computed Tomography Angiographic Features of Anomalous Origination of the Coronary Arteries in Adult Patients: A Literature Review and Coronary Computed Tomography Angiographic Illustrations

Computed tomography angiography not only detects atherosclerotic coronary artery disease but also helps delineate the anomalous coronary arterial anatomy that may be more than just an incidental finding and could contribute to patients' symptomatology. Additionally, identification of coronary artery anomalies is clinically significant for preoperative planning and optimizing the approach for coronary catheterizations or surgical treatments. In this work, we review rare origination anomalies of coronary arteries and illustrate their characteristics through computed tomography images.

Overview of coronary artery variants, aberrations and anomalies

Coronary artery anomalies and variants are relatively uncommon congenital disorders of the coronary artery anatomy and constitute the second most common cause of sudden cardiac death in young competitive athletes. The rapid advancement of imaging techniques, including computed tomography, magnetic resonance imaging, intravascular ultrasound and optical coherence tomography, have provided us with a wealth of new information on the subject. Anomalous origin of a coronary artery from the contralateral sinus is the anomaly most frequently associated with sudden cardiac death, in particular if the anomalous coronary artery has a course between the aorta and the pulmonary artery. However, other coronary anomalies, like anomalous origin of the left coronary artery from the pulmonary artery, atresia of the left main stem and coronary fistulae, have also been implicated in cases of sudden cardiac death. Patients are usually asymptomatic, and in most of the cases, coronary anomalies are discovered incidentally during coronary angiography or on autopsy following sudden cardiac death. However, in some cases, symptoms like angina, syncope, heart failure and myocardial infarction may occur. The aims of this article are to present a brief overview of the diverse coronary variants and anomalies, focusing especially on anatomical features, clinical manifestations, risk of sudden cardiac death and pathophysiologic mechanism of symptoms, as well as to provide valuable information regarding diagnostic workup, follow-up, therapeutic choices and timing of surgical treatment.

Coronary Artery Abnormalities as the Cause of Sudden Cardiac Death: A 20-Year Review

In this case series, we delve into the database of medicolegal cases of the Forensic Pathology Department at Hamilton Health Sciences in Hamilton Ontario from the last 20 years (1996-2017), and review cases of sudden cardiac death due to coronary artery abnormalities. We found 17 cases that fit the criteria, which gave us an incidence of 1.34 per 1000 cases. These cases were further audited for age, sex, type of coronary artery abnormality, symptoms before demise, circumstances of death, presence of significant atherosclerotic disease, and toxicology. Two more recent cases underwent postmortem genetic testing, and we reported on the result of one of these molecular studies. In our case series, the most commonly affected coronary artery was the right coronary artery, with the most common anomaly being abnormal origin from the left sinus of Valsalva. Although the literature maintains that left coronary artery from the opposite sinus is associated with higher incidence of SCD, our study shows that RCAs from the opposite aortic sinus, including those deemed to be low risk by classification, can be causes of SCD.

A potential protective element of myocardial bridge against severe obstructive atherosclerosis in the whole coronary system

BACKGROUND

Myocardial bridge (MB) is generally described as a congenital benign variation. Previous studies have suggested that MB prevents atherosclerotic plaques from accumulating within the bridge segment but promotes coronary stenosis in the proximal segment adjacent to MB. However, it is still not clear whether MB has positive or negative effects on severe obstructive atherosclerosis in the whole coronary artery system.

METHODS

In this study, 6774 patients with symptoms of angina who were clinically diagnosed coronary artery disease (CAD) or suspected CAD underwent coronary angiography (CAG) in our center. The presence of MB was diagnosed, and a retrospective analysis was performed between MB and severe obstructive CAD requiring percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) in the whole coronary system.

RESULTS

Among 6774 patients, 3583 (52.89%) were diagnosed with severe obstructive CAD (SOCAD) requiring a treatment of PCI or CABG and enrolled into the SOCAD group; and 3191 (47.11%) without SOCAD into the non-SOCAD group. Non-SOCAD and SOCAD groups had 512(16.05%) and 66(1.84%) patients with MB, respectively (P <  0.0001). The rate of SOCAD requiring PCI or CABG in patients with MB was much lower than that in patients without MB (11.42% vs. 56.76%, P <  0.0001). After adjusting for sex, age, diabetes mellitus, hypertension, and other risk factors, MB still had some positive role in preventing severe obstructive CAD (log-OR = - 2.134, p-value < 0.0001) through logistic regression.

CONCLUSIONS

Our results provided a clue that MB might act as a potential protective element against severe obstructive atherosclerosis in the whole coronary artery system.

Coronary artery anomalies overview: The normal and the abnormal

The aim of this review is to give a comprehensive and concise overview of coronary embryology and normal coronary anatomy, describe common variants of normal and summarize typical patterns of anomalous coronary artery anatomy. Extensive iconography supports the text, with particular attention to images obtained in vivo using non-invasive imaging. We have divided this article into three groups, according to their frequency in the general population: Normal, normal variant and anomaly. Although congenital coronary artery anomalies are relatively uncommon, they are the second most common cause of sudden cardiac death among young athletes and therefore warrant detailed review. Based on the functional relevance of each abnormality, coronary artery anomalies can be classified as anomalies with obligatory ischemia, without ischemia or with exceptional ischemia. The clinical symptoms may include chest pain, dyspnea, palpitations, syncope, cardiomyopathy, arrhythmia, myocardial infarction and sudden cardiac death. Moreover, it is important to also identify variants and anomalies without clinical relevance in their own right as complications during surgery or angioplasty can occur.

Congenital coronary artery anomalies for the pathologist

Congenital coronary artery anomalies are rare. Pathologists are exposed to those in mainly two settings; in association with sudden death and usually extreme exercise in young adults, and in association with complex congenital heart disease in the pediatric and perinatal population. Pediatric pathologists, other pathologists and pathologists' assistants performing pediatric or forensic autopsies therefore need to be familiar with coronary artery anomalies.

Morphological aspects of myocardial bridges

Although some myocardial bridges can be asymptomatic, their presence often causes coronary disease either through direct compression of the "tunnel" segment or through stimulation and accelerated development of atherosclerosis in the segment proximally to the myocardial bridge. The studied material contained 30 human hearts received from the Department of Anatomy. The hearts were preserved 3 to 5 days in 10% formalin solution. Thereafter, the fatty tissue was removed and arterial blood vessels prepared by careful dissection with special reference to the presence of the myocardial bridges. Length and thickness of the bridges were measured by the precise electronic caliper. The angle between the myocardial bridge fibre axis and other axis of the crossed blood vessel was measured by a goniometer. The presence of the bridges was confirmed in 53.33% of the researched material, most frequently (43.33%) above the anterior interventricular branch. The mean length of the bridges was 14.64 ± 9.03 mm and the mean thickness was 1.23 ± 1.32 mm. Myocardial bridge fibres pass over the descending blood vessel at the angle of 10-90 degrees. The results obtained on a limited sample suggest that the muscular index of myocardial bridge is the highest for bridges located on RIA, but that the difference is not significant in relation to bridges located on other branches. The results obtained suggest that bridges located on other branches, not only those on RIA, could have a great contractive power and, consequently, a great compressive force, which would be exerted on the wall of a crossed blood vessel.

Myocardial bridging analysis by coronary computed tomographic angiography in a Saudi population

AIM: To assess the incidence, location, morphology and clinical association of myocardial bridging in a Saudi population using coronary computed tomographic angiography (CCTA).

METHODS: A total of 350 CCTA of Saudi patients were included in this study (236 men, 114 women) with a mean age of 56.3 years. All patients were examined for appropriateness criteria of CCTA indications (typical chest pain, recent onset cardiomyopathy, left bundle branch block, etc.). The scans were retrospectively reviewed for the presence of myocardial bridging and any other pathological association.

RESULTS: Myocardial bridging was found in 89 of 350 (22.5%) patients. Most of the intramuscular segments were of the superficial type and found in the mid left anterior descending (LAD) (24.6%), followed by distal LAD (3.7%), diagonal branches (2%), ramus intermedius artery (1.4%) and obtuse marginal artery (0.8%). No myocardial bridging was detected in the right coronary or circumflex arteries. No significant differences were found between males and females (P = 0.14). Coronary artery atherosclerosis was found in 51 of 89 (57.3%) patients with MB. Atherosclerotic plaques were not detected in the intramuscular or distal segment of bridging arteries. Dynamic compression was observed in 35 (94.5%) patients with full encasement. No evidence of myocardial hypoperfusion was found in the territories supplied by the bridging arteries.

CONCLUSION: CCTA is excellent in analyzing myocardial bridging in a Saudi population and the results are comparable to other populations. However, finding the real incidence may need a large multicenter study.

Prevalence and predictors of bridging of coronary arteries in a large Indonesian population, as detected by 64-slice computed tomography scan

BACKGROUND

Multislice computed tomography (MSCT) can be used to detect myocardial bridging (MB) of coronary arteries. However, most published studies included small cohorts and did not collect data about predictors. We investigated prevalence and predictors of MB in an Indonesian population.

METHODS

All patients who had MSCT at Cinere Hospital, Jakarta, Indonesia between 2006 and 2009 were included in a prospective registry. MB was defined when at least half of the coronary artery was imbedded within the myocardium with a normal epicardial course of the proximal and distal portion.

RESULTS

Of the 934 patients (mean age 53 years, 37.8 % female), MB could be observed in 152 patients (16.3 %). Patients with MB were younger compared with those without MB. Coronary risk factors were not different between the two groups. Coronary calcifications and moderate to severe coronary stenoses were less prevalent in patients with MB, also after adjusting for differences in age. At the time of diagnosis, only a few patients with MB were treated with beta-blockers (35 %) or calcium channel blockers (13 %).

CONCLUSIONS

Prevalence of myocardial bridging as detected by MSCT is relatively high. Patients with MB were younger and had a lower prevalence of coronary sclerosis. MB could be the cause of their unexplained symptoms. Follow-up studies are necessary to assess the symptoms of these patients, their response to treatment and the incidence of (coronary) events. MSCT can be used to identify patients for potential new treatment strategies.

Myocardial bridging: what have we learned in the past and will new diagnostic modalities provide new insights?

The clinical significance of myocardial bridging has been a subject of discussion and controversy since the introduction of coronary arteriography (CAG) in the early 1960s. More recently computed tomography coronary angiography (CTCA) has made it possible to visualise the overlying muscular bands and appears to have a higher sensitivity for detecting myocardial bridging than CAG. Combining CTCA with invasive techniques such as CAG should make it possible to improve our understanding of the pathophysiology of myocardial bridging and to provide answers to hitherto unresolved questions. This paper critically reviews the outcomes of previous studies and defines remaining questions that should be answered to optimise the management of the presumably fast growing number of patients in whom a diagnosis of myocardial bridging has been made.

Myocardial bridging on coronary CTA: an innocent bystander or a culprit in myocardial infarction?

Myocardial bridging describes the clinical entity whereby a segment of coronary artery is either partially or completely covered by surrounding myocardium. It represents the most frequent congenital coronary anomaly and has an estimated prevalence of ≤13% on angiographic series. With the emergence of cardiac computed tomography and its ability to simultaneously image the coronary arteries and also the myocardium, there has been an apparent increase in the detection rates of myocardial bridges (prevalence as high as 44%). It has now become important to evaluate their clinical significance. Myocardial bridging is generally considered a benign entity with survival rates of 97% at 5 years; however, there is now emerging evidence that certain myocardial bridge characteristics may be associated with cardiovascular morbidity. The length and depth of myocardial bridges have been associated with increased atherosclerosis, whereas the degree of systolic compression has been associated with ischemia on myocardial perfusion single-photon emission tomography. On the basis of current evidence, it appears that limiting further testing for ischemia to symptomatic patients with long and/or deep myocardial brides would be appropriate.

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.

Anatomical characteristics of myocardial bridge in patients with myocardial infarction by multi-detector computed tomography

BACKGROUND

Recent development of multi-detector computed tomography (MDCT) has made the detection of myocardial bridge (MB) easier on the left anterior descending coronary artery (LAD). The LAD segment proximal to the MB is well known to be susceptible to atherosclerosis. Anatomical characteristics of MB on LAD in patients with myocardial infarction (MI) were examined by MDCT.

METHODS AND RESULTS

Subjects were 43 MI patients who had MB in the LAD and comprised 2 groups: 14 with culprit lesions in the LAD proximal to MB (culprit group) and 29 without culprit lesions in the LAD (non-culprit group). MB length, MB thickness, and the distance from the orifice of left main trunk (LMT) to MB entrance were compared. Age and coronary risk factors showed no significant difference between the 2 groups. MB length (P=0.011), MB thickness (P=0.035), and index of the length multiplied by thickness of MB (P=0.031) were significantly greater in the culprit group. The distance from the orifice of the LMT to MB entrance was significantly shorter in the culprit group (P=0.006).

CONCLUSIONS

Anatomical properties of MB, such as length and thickness of MB as well as MB location, are associated with the formation of culprit lesions of LAD proximal to MB in MI.

Coronary artery perforation following implantation of a drug-eluting stent rescued by deployment of a covered stent in symptomatic myocardial bridging

We successfully rescued a patient whose coronary artery perforated following implantation of a drug-eluting stent (DES), by deploying a stent-graft in symptomatic myocardial bridging. Our case demonstrated that coronary perforation could be handled without difficulty when perforated myocardial bridging is confined to the interventricular groove

(1) coronary events caused by myocardial bridge

Myocardial bridge (MB), which covers a part of the left anterior descending coronary artery (LAD), is a normal anatomical variant structure (45% in frequency by autopsy) in LAD. MB contraction plays the role of a "double-edged sword" on the coronary events, suppressing coronary atherosclerosis under the MB, yet generating abnormal blood flow associated with coronary heart diseases (CHDs). High shear stress driven by MB compression causes the suppression of vascular permeability and vasoactive protein expression such as e-NOS and endothelin-1, which leads to the suppression of atherosclerosis in the LAD segment under the MB. However, despite the prevalent view of MB as benignancy by conventional coronary angiography (5-6% in frequency), with advance of imaging technique such as multislice spiral computed tomography [(MSCT); 16% in frequency], cardiologists are now frequently aware of symptomatic MB occurring not only in hospitalized patients, but also in young athletes free from atherosclerosis. Moreover, the large mass volume of MB muscle induces atherosclerosis evolution at the settled site in LAD proximal to MB and contributes to the occurrence of myocardial infarction. These events upon the coronary events result from the different pathophysiological mechanisms induced by contractile force of MB, which is solely determined just by the integration of anatomical properties of MB, such as the location, length and thickness of MB in an individual LAD. A recent MSCT provides the objective quantification of the anatomical variables that correlate with the histopathological results in relation to the occurrence of CHD. In this review, we therefore discuss the necessity to explore MB as a inherent chance anatomical risk factor for CHD.

Myocardial bridging in Taiwan: depiction by multidetector computed tomography coronary angiography

BACKGROUND/PURPOSE

Myocardial bridging (MB) is a condition in which a segment of the major epicardial coronary artery is tunneled within and surrounded by the myocardium. This condition has been linked to severe complications. The aim of this study was to evaluate the incidence of MB in Taiwanese subjects examined with electrocardiogram-gated, 16-slice, multidetector computed tomography (MDCT) coronary angiography, as well as to determine the location, depth, and length of the bridged segments and the concomitant atherosclerosis of MB.

METHODS

From August 2004 to May 2005, 276 consecutive subjects referred to our department for MDCT coronary angiography were enrolled in the study after written informed consent was obtained from each participant.

RESULTS

Twenty-four subjects (8.7%) had at least one coronary segment that was completely surrounded by myocardium. Patients ranged in age from 27 to 76 years, with an average of 54 +/- 12 years. Thirty coronary segments were found to have MB. The most common location of MB was in segment 7, which accounted for 14 coronary segments (46.7%) of the total number of bridged segments; left anterior descending artery (LAD) segments accounted for 23 (76.7%); and right coronary artery and left circumflex artery segments accounted for three (10%) and two (6.7%), respectively. The length of bridged segments ranged from 5.2 to 50.6 mm, with an average length of 24.6 +/- 11.8 mm, and the depth of the bridged segments ranged from 0.5 to 9.1 mm, with an average depth of 3.65 +/- 1.89 mm. Two bridged segments (6.7%) had concomitant atherosclerosis; these were located in segment 7 (24.0 mm long and 6.10 mm deep) and segment 8 (27.1 mm long and 7.0 mm deep). Bridged segments with concomitant atherosclerosis were deeper, but not longer, compared with bridged segments without concomitant atherosclerosis (p < 0.05).

CONCLUSION

Electrocardiogram-gated MDCT is an effective noninvasive tool for evaluating MB in a clinical setting. The most common location of MB was in the LAD, especially in segment 7. Bridged segments with concomitant atherosclerosis were deeper, but not longer, compared with bridged segments without concomitant atherosclerosis.

Anatomic Properties of Myocardial Bridge Predisposing to Myocardial Infarction

Background— A myocardial bridge (MB) that partially covers the course of the left anterior descending coronary artery (LAD) sometimes causes myocardial ischemia, primarily because of hemodynamic deterioration, but without atherosclerosis. However, the mechanism of occurrence of myocardial infarction (MI) as a result of an MB in patients with spontaneously developing atherosclerosis is unclear.

Methods and Results— One hundred consecutive autopsied MI hearts either with MBs [MI(+)MB(+) group; n=46] or without MBs (n=54) were obtained, as were 200 normal hearts, 100 with MBs [MI(−)MB(+) group] and 100 without MBs. By microscopy on LADs that were consecutively cross-sectioned at 5-mm intervals, the extent and distribution of LAD atherosclerosis were investigated histomorphometrically in conjunction with the anatomic properties of the MB, such as its thickness, length, and location and the MB muscle index (MB thickness multiplied by MB length), according to MI and MB status. In the MI(+)MB(+) group, the MB showed a significantly greater thickness and greater MB muscle index ( P <0.05) than in the MI(−)MB(+) group. The intima-media ratio (intimal area/medial area) within 1.0 cm of the left coronary ostium was also greater ( P <0.05) in the MI(+)MB(+) group than in the other groups. In addition, in the MI(+)MB(+) group, the location of the segment that exhibited the greatest intima-media ratio in the LAD proximal to the MB correlated significantly ( P <0.001) with the location of the MB entrance, and furthermore, atherosclerosis progression in the LAD proximal to the MB was largest at 2.0 cm from the MB entrance.

Conclusions— In the proximal LAD with an MB, MB muscle index is associated with a shift of coronary disease more proximally, an effect that may increase the risk of MI.

Sudden adult death

In the investigation of sudden death in adults, channelopathies, such as long QT syndrome, have risen to the fore in the minds of forensic pathologists in recent years. Examples of these disorders are touched upon in this review as an absence of abnormal findings at postmortem examination is characteristic and the importance of considering the diagnosis lies in the heritable nature of these conditions. Typically, a diagnosis of a possible channelopathy is evoked as an explanation for a 'negative autopsy' in a case of apparent sudden natural death. However, the one potential adverse effect of this approach is that subtle causes of sudden death may be overlooked. The intention of this article is to review and discuss potential causes of sudden adult death (mostly natural) that should be considered before resorting to a diagnosis of possible channelopathy. Nonetheless, it becomes apparent that many of the potential causes of sudden death can have a genetic basis. Thus, it becomes an important consideration that there may be a genetic basis to sudden death that extends beyond the negative autopsy.

Myocardial bridging, a frequent component of the hypertrophic cardiomyopathy phenotype, lacks systematic association with sudden cardiac death

AIMS

The clinical significance attributable to myocardial bridging of left anterior descending coronary artery in hypertrophic cardiomyopathy (HCM) remains controversial.

METHODS AND RESULTS

Prevalence and depth of coronary artery bridges (CBs) were assessed in 255 hearts, including 115 with HCM (median age 29, range 5-90; 75% male), and 140 controls. Coronary artery bridges were more common in HCM (47/115; 41%) than in patients who died of a variety of non-HCM-related causes (21/100; 21%; P = 0.002), or in patients with congenital aortic stenosis and left ventricular (LV) hypertrophy (5/40; 12%; P = 0.001). Among the HCM hearts, CBs were present in 33 of 77 patients (43%) with sudden death, in 10 of 27 (37%) with heart failure death (or heart transplantation), and in 4 of 11 (36%) with other modes of death (P = 0.826). Deeply embedded CBs (> or =2 mm) occurred with similar frequency in HCM patients with sudden (21 of 77; 27%) or heart failure death (5 of 27; 13%; P = 0.191). In sudden death patients, the presence of CB was unrelated to gender (33% in women and 45% in men, P = 0.406) and age (41% <18 years vs. 44% > or =18 years; P = 0.827).

CONCLUSION

In this morphological analysis of more than 250 hearts, CBs are a frequent component of phenotypically expressed HCM, and more common than in other disorders with or without LV hypertrophy. Although no systematic association with HCM-related sudden death is evident, our findings do not exclude the possibility that CB could contribute to increased risk in some individual patients, potentially impacting management decision-making on a case-by-case basis.

Myocardial bridging: depiction rate and morphology at CT coronary angiography--comparison with conventional coronary angiography

PURPOSE

To prospectively assess the depiction rate and morphologic features of myocardial bridging (MB) of coronary arteries with 64-section computed tomographic (CT) coronary angiography in comparison to conventional coronary angiography.

MATERIALS AND METHODS

Patients were simultaneously enrolled in a prospective study comparing CT and conventional coronary angiography, for which ethics committee approval and informed consent were obtained. One hundred patients (38 women, 62 men; mean age, 63.8 years +/- 11.6 [standard deviation]) underwent 64-section CT and conventional coronary angiography. Fifty additional patients (19 women, 31 men; mean age, 59.2 years +/- 13.2) who underwent CT only were also included. CT images were analyzed for the direct signs length, depth, and degree of systolic compression, while conventional angiograms were analyzed for the indirect signs step down-step up phenomenon, milking effect, and systolic compression of the tunneled segment. Statistical analysis was performed with Pearson correlation analysis, the Wilcoxon two-sample test, and Fisher exact tests.

RESULTS

MB was detected with CT in 26 (26%) of 100 patients and with conventional angiography in 12 patients (12%). Mean tunneled segment length and depth at CT (n = 150) were 24.3 mm +/- 10.0 and 2.6 mm +/- 0.8, respectively. Systolic compression in the 12 patients was 31.3% +/- 11.0 at CT and 28.2% +/- 10.5 at conventional angiography (r = 0.72, P < .001). With CT, a significant correlation was not found between systolic compression and length (r = 0.16, P = .25, n = 150) but was found with depth (r = 0.65, P < .01, n = 150) of the tunneled segment. In 14 patients in whom MB was found at CT but not at conventional angiography, length, depth, and systolic compression were significantly lower than in patients in whom both modalities depicted the anomaly (P < .001, P < .01, and P < .001, respectively).

CONCLUSION

The depiction rate of MB is greater with 64-section CT coronary angiography than with conventional coronary angiography. The degree of systolic compression of MB significantly correlates with tunneled segment depth but not length.

The Angiographic Aspects of Myocardial Bridges in Turkish Patients who have Undergone Coronary Angiography

Introduction: Little is known of the clinical significance of myocardial bridges, which may be recognised as the narrowing of the systolic coronary artery as seen in an angiography. In this study, our goal was to review the literature information about the anatomic aspects, the clinical manifestations and implications, and the angiographic characteristics. Materials and Methods: The angiographic data of 7200 adult patients undergoing coronary angiography were retrospectively analysed for the diagnosis of myocardial bridge. The main angiographic evidence of a myocardial bridge that we required was the narrowing of a systolic coronary artery resulting in at least 50% reduction of lumen diameter in comparison with the diastolic phase. All coronary angiograms were reviewed independently by at least 2 of the authors and the case was included only if there was a consensus that the myocardial bridge resulted in 50% narrowing or more. Results: Myocardial bridge was present in 29 (0.4%) of the 7200 coronary angiographies. The location of the myocardial bridge was in the left anterior descending coronary artery in 28 cases (96.5%), and the left circumflex coronary artery in 1 case (3.4%). Myocardial bridge was most common in the middle segment of the left anterior descending coronary artery (78.5 %). Each of these patients with myocardial bridge was referred for angiography because of symptom of chest pain alone or symptom of chest pain, palpitations and dyspnoea. Of the 29 patients with myocardial bridge, 2 patients without any symptom, demonstrated ischaemia as assessed by Tc-99m MIBI myocardial perfusion scintigraphy. Conclusion: Chest pain was the common reason for angiography in patients with myocardial bridge. The incidence of myocardial bridge may vary according to population. Myocardial bridge is more frequently found in the middle segment of the left anterior descending coronary artery. Key words: Angiography, Myocardial bridge, Population

Could increased axial wall stress be responsible for the development of atheroma in the proximal segment of myocardial bridges?

BACKGROUND

A recent model describing the mechanical interaction between a stenosis and the vessel wall has shown that axial wall stress can considerably increase in the region immediately proximal to the stenosis during the (forward) flow phases, so that abnormal biological processes and wall damages are likely to be induced in that region. Our objective was to examine what this model predicts when applied to myocardial bridges.

METHOD

The model was adapted to the hemodynamic particularities of myocardial bridges and used to estimate by means of a numerical example the cyclic increase in axial wall stress in the vessel segment proximal to the bridge. The consistence of the results with reported observations on the presence of atheroma in the proximal, tunneled, and distal vessel segments of bridged coronary arteries was also examined.

RESULTS

1) Axial wall stress can markedly increase in the entrance region of the bridge during the cardiac cycle. 2) This is consistent with reported observations showing that this region is particularly prone to atherosclerosis.

CONCLUSION

The proposed mechanical explanation of atherosclerosis in bridged coronary arteries indicates that angioplasty and other similar interventions will not stop the development of atherosclerosis at the bridge entrance and in the proximal epicardial segment if the decrease of the lumen of the tunneled segment during systole is not considerably reduced.

Drug eluting stent implantation for the treatment of symptomatic myocardial bridging is associated with favorable peri-procedural results and short-term outcomes

Myocardial bridging is the most common congenital coronary abnormality, and is frequently found on post-mortem cardiac examination. Although often asymptomatic, clinical presentation can vary from unstable angina to sudden cardiac death. Only isolated cases of using drug eluting stents (DES) for bridging segments have been described. Our objective was to retrospectively analyze a series of patients undergoing percutaneous coronary intervention (PCI) with DES for symptomatic myocardial bridging and follow post-procedure outcomes. Results revealed favorable peri-procedural angiographic and short-term clinical results with DES implantation. Although initial data regarding DES implantation for symptomatic myocardial bridging are promising, long-term follow up, particularly related to in-stent restenosis will be important.

Myocardial bridging of coronary arteries: A risk factor for myocardial fibrosis?

Myocardial bridging of a coronary artery is an anatomic anomaly in which a major epicardial coronary artery extends intramurally into the myocardium for a part of the vessel's course. The left anterior descending coronary artery (LAD) is most frequently involved. Myocardial bridging is often asymptomatic, although myocardial pathology, arrhythmias and sudden cardiac death have been reported. In this study we quantitated the degree of myocardial intersitial fibrosis in histological sections of the anterior wall of the left ventricle obtained from the hearts of 6 individuals with myocardial bridging of the LAD and compared it to age-, weight-, and sex-matched controls without bridging. We found that patients with the bridging of the LAD had 33% increased myocardial interstitial fibrosis as compared to the control group (P=0.0006). Our data suggest that myocardial bridging may be an independent risk factor for development of myocardial ischemia and interstitial fibrosis.

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 bridge and evaluation of its anatomical properties by coronary multislice spiral computed tomography

BACKGROUND

Myocardial bridge (MB) is a common anatomical condition, under which a part of the coronary artery running in the epicardial adipose tissue, is covered with myocardial tissue. It regulates atherosclerosis development and sometimes evokes coronary heart disease through haemodynamic alterations. We attempted to efficiently detect MB and evaluate the anatomical properties of MB by coronary multislice spiral computed tomography (MSCT).

METHODS

Sixteen-row MSCT was conducted on 148 patients with coronary heart disease. MSCT images were reconstructed and reformed with transverse scans, curved planar reformat and three-dimensional volume-rendered images. The MB, over 1.0 mm in thickness, was identified by the presence of the "step-down and step-up" appearance. After "trial and error" essays, we could consistently examine the frequency of MB and evaluate the anatomical properties of MB, especially its thickness, together with coronary wall lesions.

RESULTS

Twenty-three patients (15.8%) had MB over 1.0 mm in thickness: 21 MBs (87.5%) were located in the left anterior descending artery with a mean thickness and length of 1.8+/-0.7 and 20.0+/-8.6 mm. Moreover, although the tunneled segment beneath MB was always free of coronary wall lesions, 79.2% (19/24) of the segments proximal to MB demonstrated coronary wall lesions. Of special significance were three symptomatic MB patients without any atherosclerotic lesion throughout all the coronary arteries.

CONCLUSION

Coronary MSCT is a new imaging technique that provides a non-invasive diagnostic tool for MB and yields much better results of MB detection than previous imaging methods.

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.

Significance of anatomical properties of myocardial bridge on atherosclerosis evolution in the left anterior descending coronary artery

Myocardial bridge (MB) is frequently detected in the left anterior descending coronary artery (LAD), and LAD intima under MB is significantly spared from atherosclerotic evolution. Significance of anatomical features of MB on the extent of atherosclerosis of LAD was histomorphometrically investigated. Full-length 200 LADs with MB and 100 control LADs without MB were cross-sectioned at 5 mm intervals, and atherosclerosis ratio and intimal lesion types were evaluated. In cases with MB located within 5 cm from the left coronary ostium, atherosclerosis ratio in the proximal part of LAD was significantly lower than in control group, but, in cases with MB locating more than 5 cm from the ostium, atherosclerosis ratio in this part was similar to that in control cases. MB thickness was significantly correlated with its length, and the longer the MB the more proximally it tended to be located in LAD. Atherosclerosis ratio under MB was lower in cases with thick or long MBs than in cases with thinner or shorter MBs. In addition, intimal lesion in segments proximal to MB tended to be eccentric. Our results suggest that these anatomical properties of MB are the critical modulators for atherosclerosis evolution in the entire course of LAD.

Multidetector row computed tomography: imaging congenital coronary artery anomalies in adults

The quality of the imaging of the main coronary arteries and side branches provided by multidetector row computed tomography (MDCT) may have importance when assessing congenital coronary artery anomalies. This review discusses the rationale for using MDCT for this indication and examines the advantages and disadvantages of the technique. Examples of MDCT imaging of congenital coronary artery anomalies are presented. These images provide persuasive evidence to support clinical use of MDCT cardiac imaging in the context of suspected congenital coronary artery anomalies as a first line investigation.