[Muscle bridges over the left anterior descending coronary artery: their influence on arterial disease (author's transl)]

Implications of Myocardial Bridge on Coronary Atherosclerosis and Survival

Background: In this study, we aimed to describe the impact of MBs on atherosclerosis and survival, in patients with coronary artery disease (CAD). Methods: We retrospectively studied 1920 consecutive patients who underwent conventional coronary angiography for suspected CAD. Atherosclerotic load (AL), defined as the sum of degrees of stenosis, and general atherosclerotic load (GAL), representing the sum of AL, were compared between patients with MB and a control group without MB; patients in these groups were similar in age and sex. We assessed survival at 10 years after the last enrolled patient. Results: Prevalence of MB was 3.96%, predominantly in the mid-segment of left anterior descendent artery (LAD). In the presence of MB, GAL was lower (158.1 ± 93.7 vs. 205.3 ± 117.9, p = 0.004) with a lesser AL in the proximal (30.3 ± 39.9 vs. 42.9 ± 41.1, p = 0.038) and mid-segments (8.1 ± 20.0 vs. 25.3 ± 35.9, p < 0.001) of LAD. Based on a Multinominal Logistic Regression, we found that the presence of MB on LAD (regardless of its location on this artery) is a protective factor against atherosclerotic lesions, decreasing the probability of significant stenosis, especially of those ≥70%, on the entire artery (B −1.539, OR 4660; 95% CI = 1.873−11.595, p = 0.001) and on each of its segments as well: proximal LAD (B −1.275, OR 0.280; 95% CI = 0.015−5.073; p = 0.038), mid-LAD (B −1.879, OR 6.545; 95% CI = 1.492−28.712; p = 0.013) and distal LAD (B −0.900, OR 2.459, 95% CI = 2.459−2.459, p = 0.032). However, 10-year survival was similar between groups (76.70% vs. 74.30%, p = 0.740). Conclusion: The presence of MB on LAD proved to be a protective factor against atherosclerosis for the entire artery and for each of its segments, but it does not influence long-term survival in patients with CAD.

Clinical characteristics and factors associated with coronary stenosis proximal to a myocardial bridge: a retrospective study

BACKGROUND

The association of myocardial bridge (MB) with cardiovascular risk and the possible cardiovascular risk factors remain unclear. This study aimed to explore the clinical characteristics and related factors of coronary stenosis proximal to an MB.

METHODS

This was a retrospective study of patients with symptoms of coronary atherosclerotic heart disease admitted between 10/2011 and 12/2014 to the Emergency and Cardiology Department of Bayannur Hospital, who underwent selective coronary angiography (SCAG). The patients were assigned to the non-stenosis and stenosis groups according to whether coronary stenosis was proximal to the MB.

RESULTS

Among 244 patients with MB and cardiovascular symptoms, 91 (37.3%) had stenosis proximal to the MB. Compared with the non-stenosis group, there were more males (80.2% vs. 55.6%, P < 0.001) and smokers (including those who had quit smoking) (P < 0.001) in the stenosis group. There were no significant differences in blood lipid-related indexes (TG, TC, HDL-C, LDL-C, and VLDL-C) between the two groups. Multivariable analysis suggested that MB location in the middle distal or distal segment of the left anterior descending artery (LAD) increased the odds of coronary stenosis proximal to the MB (OR = 0.439, 95% CI: 1.57-7.532, P = 0.002), which was then considered an independent factor associated with coronary stenosis proximal to the MB.

CONCLUSIONS

In patients diagnosed with an MB by SCAG, only MB located in the middle distal or distal segment of the LAD is independently associated with coronary stenosis proximal to the MB.

Myocardial bridge as a structure of "double-edged sword" for the coronary artery

Myocardial bridge (MB) is a chance anatomical structure, comprised of the myocardial tissue, with which the coronary artery running in epicardial adipose tissue is partly covered. It is predominantly present in the left anterior descending artery (LAD) and recognizable through imaging techniques as changes in blood flow within the LAD that arises from MB contraction at cardiac systole. Such changes in blood flow influence the pathophysiology of coronary circulation and atherosclerosis development, thus generating controversy as to whether MB predisposes individual to myocardial infarction (MI). However, recent histomorphometric studies have shown that the individual anatomic properties of MB, such as location, length and thickness, consistently play a critical role in the occurrence of MI. This review article comprehensively addresses the pathophysiological mechanisms of MI occurrence together with the benign suppressive effect of coronary atherosclerosis by MB.

(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.

Prevalence of myocardial bridging detected with 64-slice multidetector coronary computed tomography angiography in asymptomatic adults

OBJECTIVE

Myocardial bridging is a congenital condition in which a segment of an epicardial artery has an intramural course within the myocardium. The aim of the present study was to evaluate the prevalence of myocardial bridging and the ability of 64-slice coronary computed tomography angiography to identify myocardial bridging in asymptomatic adults.

METHODS

One hundred sixty-nine consecutive asymptomatic subjects underwent 64-row multidetector computed tomography (MDCT) of the coronary arteries. Two experienced CT radiologists identified myocardial bridging >1 mm in thickness, by consensus. We examined the frequency of myocardial bridging and evaluated the length, thickness, and coronary wall lesions.

RESULTS

Myocardial bridges were found in 28 (17%) of 165 subjects. Twenty-one subjects (75%) had 1 bridge and 7 subjects (25%) had 2, for a total of 35 myocardial bridges. Twenty-one bridges (60%) were located in the left anterior descending, 8.5% in the diagonal branch, and 2.8% in the circumflex arteries. The segment beneath the myocardial bridge was always free of coronary wall plaques, but the arterial segment proximal to it had significant coronary wall plaques in 24 cases (68.6%).

CONCLUSION

We found that the incidence of myocardial bridging in asymptomatic adults is 7%, which is in agreement with some pathologic studies in the literature. Our study shows that MDCT of the coronary arteries is a reliable and noninvasive technique, which can accurately locate the site of myocardial bridging, and measure its thickness, course, and length.

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.

Aplastic right coronary artery and left coronary artery with a separate origin of the circumflex branch in a 31-year-old woman

Singular coronary arteries are a rare feature appearing in approximately 0.05% of the population. The clinical relevance of those anomalies varies a lot. The wide range of descriptions reaches from asymptomatic cases to sudden cardiac death. This will be discussed in a case report concerning a 31-year-old woman who was found dead in her apartment. Due to drugs that were found next to her, a suicide was assumed. The autopsy yielded an aplastic right coronary artery and a left coronary artery with an anomalous origin of the circumflex branch as well as a myocardial scar. The autopsy findings and the results of the toxicological examinations are presented and discussed in view of the cause of death.

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.

The effect of myocardial bridging of the coronary artery on vasoactive agents and atherosclerosis localization

The relationship between alterations in the immunohistochemical expression of three vasoactive agents [endothelial nitric oxide synthase (eNOS), endothelin-1 (ET-1), and angiotensin-converting enzyme (ACE)] and the occurrence human atherosclerosis was investigated in relation to the myocardial bridge (MB) of the left anterior descending coronary artery (LAD), an anatomical site that experiences increased shear stress. Five millimetre cross-sections of LADs with MB from 22 autopsied cases were taken from the left coronary ostium to the cardiac apex and were immunohistochemically stained with antibodies against eNOS, ET-1, and ACE. The extent of atherosclerosis in each section was calculated using the atherosclerosis ratio (intimal cross-sectional area/medial cross-sectional area) determined by histomorphometry. The results were analysed according to their anatomical location relative to the MB, either proximal, beneath, or distal. The extent of atherosclerosis was significantly lower beneath the MB, compared with proximal and distal segments. The expression of eNOS, ET-1, and ACE was also significantly lower beneath the MB. The expression of these agents correlated significantly with the extent of atherosclerosis. Because nitric oxide, after its production by eNOS, is believed to be degraded by superoxide radicals, the effect of eNOS expression on atherosclerosis remains controversial. However, the present findings clearly indicate that the expression of ET-1 and ACE is directly related to the development of human coronary atherosclerosis in vivo through shear stress.

Coronary vasospasm at the site of myocardial bridge--report of two cases

Two patients with angina pectoris and postmyocardial infarction angina due to coronary vasospasm at the site of myocardial bridge are described. Intracoronary injection of isosorbide dinitrate led to resolution of coronary vasospasm on acetylcholine provocation test, and vasospastic angina pectoris has been well controlled after treatment with calcium channel blockers.

The effects of a myocardial bridge on coronary atherosclerosis and ischaemia

The term myocardial bridge (MB) describes the surprisingly common situation in which part of the left anterior descending coronary artery (LAD), running in epicardial adipose tissue, is covered by a bridge of myocardial tissue. The presence of an MB may influence arterial tissue through the alteration of haemodynamic forces by the myocardial contraction of the bridge itself. Histopathologically and ultrastructurally, any manifestations of atherosclerosis elsewhere in the LAD are suppressed in the intima beneath the MB. By scanning electron microscopy, abrupt changes in endothelial cell morphology indicate that the intima beneath the bridge is protected by haemodynamic factors. Furthermore, the closer the bridge to the left coronary ostium, the greater the extent of proximal intimal thickening. In parallel with this, considering the occurrence of myocardial infarction in cases of proximal MB together with previous reports on relationships between MB and coronary ischaemia, it appears that anatomical characteristics such as the location, length, and thickness of the MB have a bearing on the effects of this abnormality. When the pathologist examines the heart at autopsy, this quite common condition should be borne in mind, in view of its potential but complex relationship to atherosclerosis and ischaemic heart disease.

Clinical Significance of Isolated Coronary Bridges

Myocardial bridging of a coronary artery has been noted in 0.5% to 1.6% of arteriograms but the clinical significance is controversial. We reviewed retrospectively 761 consecutive coronary arteriograms performed in the Chinese PLA General Hospital from 1986 to 1996. Myocardial bridging of a coronary artery was noted in 12 cases (1.5%), located exclusively in the left anterior descending coronary artery and isolated without fixed coronary artery stenosis. The bridges ranged in length from 10 to 50mm (mean 24 mm) and were classified as grade 1 (8% of cases), grade 2 (25%) and grade 3 (67%). All patients were hospitalized because of angina. Eight (67%) of the 12 patients suffered from anterioapical dyskinesia including 2 who had acute myocardial infarction with a left ventricular aneurysm. Three patients (25%) with a small posterior descending coronary artery died. In our view, when there is a hyperdominant left anterior descending coronary artery with a small posterior descending artery and a myocardial bridge, the patient appears to be in jeopardy and myocardial bridging can no longer be considered a benign coronary anomaly, especially when there is grade 3 narrowing of the left anterior descending coronary artery during systole.

High wall shear stress proximal to myocardial bridging and atherosclerosis: intracoronary ultrasound and pressure measurements

BACKGROUND

Studies have shown that myocardial bridging may prevent coronary atherosclerosis and that the segment proximal to the bridge is often sclerosed. The underlying mechanism is still unknown.

METHODS

Intracoronary ultrasound and pressure measurements were performed in a patient with myocardial bridging in the left anterior descending coronary artery. A 3.5 F, 20 MHz probe was used to measure the change in cross sectional area of the lumen during the cardiac cycle. Intracoronary pressure was measured with a Double tip, end mounted pressure transducer system, the catheter having two pressure sensors located at the end of the catheter 3 cm apart. Intracoronary pressure was recorded as the catheter was slowly advanced and pulled back through the left anterior descending coronary artery.

RESULTS

Systolic compression of the bridge segment was clearly visualised on ultrasonography and an eccentric plaque with calcium deposit was found in the segment proximal to the bridge. The pressure in the segment proximal to the bridge (160/26 mm Hg) was higher than that of the proximal normal segment (126/68 mm Hg). The pressure distal to the bridge was 68/30 mm Hg. A highly characteristic "sucking effect" was found in the bridge segment. The pressure in the bridge segment was 102/-40 mm Hg.

CONCLUSION

The pressure in the segment proximal to the myocardial bridging was higher than aortic pressure. Disturbance of blood flow and high wall stress proximal to myocardial bridging was a main contributor to the development of atherosclerosis in the segment proximal to the bridge.

Comparison of intravascular ultrasound and angiography in the assessment of myocardial bridging

BACKGROUND

In autopsy, myocardial bridging is a common finding. With coronary angiography, a systolic compression, mainly of the left anterior descending coronary artery, is observed in 1% to 3% of the patients. Controversy exists concerning the functional importance of this finding. To obtain a functional insight into the myocardial bridging, intravascular ultrasound and intracoronary Doppler were performed.

METHODS AND RESULTS

Intracoronary ultrasound and Doppler were performed in 14 patients with angiographic evidence of systolic vessel compression ("milking effect") in the left anterior descending coronary artery. The 4.8F, 20-MHz ultrasound catheter could not be advanced through the entire myocardial bridge segment in 6 of the 14 patients studied because the lumen was < 1.6 mm. In these patients, only the proximal parts of the bridge segment were scanned. The changes in cross-sectional shape during the cardiac cycle were determined for both the normal proximal segment and the bridge segment by use of a semiautomatic computer program. Intracoronary Doppler (20 MHz) was performed in 7 patients with a 3F catheter. A highly characteristic systolic eccentric or concentric compression with delayed relaxation in diastole of the myocardial bridging segment was clearly visualized in all patients. The cross-sectional lumen area variation was 40 +/- 25% in the bridging segments and 9 +/- 7% in the normal segments (P < .01). No atherosclerotic lesions were detected in the bridge or the distal segment in the 8 patients in whom the IVUS catheter was successfully advanced through the entire myocardial bridge. However, atherosclerotic plaques were found in the segments proximal to the bridge in 12 of 14 patients (86%). The resting mean flow velocity was 6.4 +/- 1.2 cm/s; the maximal mean flow velocity after intracoronary administration of 10 mg papaverine was 14.1 +/- 3.4 cm/s. The coronary flow velocity reserve was 2.2 +/- 0.7. A highly characteristic pattern showing a prominent peak in coronary velocity in early diastole was observed in 86% of patients, and this pattern was enhanced after injection of intracoronary papaverine.

CONCLUSION

Intravascular ultrasound demonstrated a characteristic systolic compression of the bridge segments. The delayed compression release may explain the characteristic sharp early diastolic peak in coronary flow velocity found with intracoronary Doppler in vessels with myocardial bridging. Reduced coronary flow reserve may be related to this phenomenon, possibly explaining signs of ischemia detected in some of the patients, but may alternatively be a result of the presence of atherosclerosis in the segment proximal to the bridge in these patients.

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

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

The relationship between the directions of myocardial bridges and of the branches of the coronary arteries in the human heart

The variations of the direction of the myocardial bundles of the bridges over coronary arteries and branches were studied in relation to the direction of the vessels over which they are found. The investigation was performed on 82 hearts of individuals whose death was accidental and unrelated to cardiac disease. The hearts were obtained from cadavers of individuals of either sex and different racial groups, whose age ranged from 7 to 68 years. The angle between the direction of the musculature and of the vessels may explain why in some cases there is no change in the structure of the "pontine portion" of the wall.

Surgical treatment of myocardial bridging causing coronary artery obstruction

Nine patients with obstruction of coronary artery blood flow caused by myocardial bridging underwent surgery after failure of medical treatment. The diagnoses were made angiographically at rest or during beta-stimulation. Impaired blood flow was found only in the left anterior descending artery in seven patients and additionally in the diagonal branch in two. The operations, performed with cardiopulmonary bypass consisted of complete dissection of the overlying myocardium. All patients survived the operation. Major intraoperative complications were accidental opening of the right ventricle in two patients. Postoperative scintigraphic and angiographic studies demonstrated restoration of coronary flow and myocardial perfusion without residual myocardial bridges under beta-stimulation. Surgical relief of myocardial ischemia due to systolic compression of intramyocardial coronary arteries can be accomplished with low operative risk and with excellent functional results.

Incidence and clinical significance of bridges of myocardium over the coronary arteries and their branches

The incidence of bridges of myocardium seen on the external surface of the heart, through the epicardium, over portions of coronary arteries and their branches, was studied in 50 cadavers and found to be 78%. The bridges of the myocardium varied in size and in number (from one to six). Their location was predominantly found at the level of the anterior ventricular branch of the left coronary artery also called left anterior descending artery (52%), whereas in the territory of the right coronary artery the highest percentage was at the level of the anterior ventricular branch (12%). This myocardio-arterial relationship might be responsible for periodic or permanent reduction of the lumen, partial or total arterial obliteration, ischemia, atherosclerosis, angina, and sudden death.

The significance of myocardial bridge upon atherosclerosis in the left anterior descending coronary artery

The relation between myocardial bridges (MB) and atherosclerosis in the left anterior descending coronary artery (LAD) was explored using morphometric methods in 642 hearts. The location of myocardial bridges in the LAD was classified according to distribution as proximal, middle and distal. Myocardial bridges were found in 48 per cent of males and 36 per cent of females. When proximal myocardial bridging was present intimal thickening and macroscopic raised lesion were increased just before the bridge as compared with the corresponding site in the other two categories. Underneath bridges eccentric plaques and raised lesions are absent although there is often concentric intimal thickening. The overall frequency of myocardial infarction was the same in patients with and without myocardial bridges. However, when infarction occurred in the patients having bridges, it was almost confined to those in the proximal group despite this being infrequent in the general distribution of myocardial bridges in the left anterior descending artery. It is postulated that hypertension may enhance infarction in the case of myocardial bridges in the very proximal left anterior descending artery. It is concluded that the location of myocardial bridges greatly alters the distribution of physical force against the arterial wall and influences the extent of atherosclerosis.

[Forensic medicine aspects of fatal coronary insufficiency with normal coronary arteries]

Clinical experiences give examples for the existence of various courses of anginal symptomatology even with cases of sudden heart death demonstrating angiographically normal coronary arteries. Pathogenetically may be considered spasms of regular or little changed coronary arteries, coronary muscle bridges and acute arrhythmias. In cases of recurrent myocardial ischemias an interstitial fibrosis and endocardial fibrosis can be proved histologically in the myocardial supply area. However an acute coronary insufficiency based on rheological and metabolic etiology cannot be found with morphological methods. The results are discussed, considering forensic aspects in cases of competitive causes of death.