Severe coronary tortuosity or myocardial bridging in patients with chest pain, normal coronary arteries, and reversible myocardial perfusion defects

Coronary Tortuosity Index vs. Angle Measurement Method for the Quantification of the Tortuosity of Coronary Arteries in Non-Obstructive Coronary Disease

Coronary tortuosity has been recognized as a potential pathophysiological mechanism in the development of non-obstructive coronary artery disease (CAD). The aim of this study was to examine the role of two coronary tortuosity measurement methods in the detection of clinically significant coronary tortuosity. The study included 160 patients with angina symptoms and myocardial ischemia detected by cardiac stress tests in chronic settings and those diagnosed with acute coronary syndrome. After coronary angiography, tortuosity of coronary arteries was assessed by two methods, including measurement of tortuosity angles and calculating of tortuosity index. Significantly more tortuous coronary arteries were detected in the group with non-obstructive CAD (p < 0.01 for all three arteries), with significantly higher tortuosity index (TI) for all three coronary arteries in this group of patients, compared to patients with obstructive CAD. The highest TI for LCX was found in patients with lateral ischemia (p < 0.001) and for LAD in patients with anterior ischemia (p < 0.001). When measured by the angle method, the only association was found between LCX tortuosity and lateral ischemia (OR 4.9, p = 0.046). In conclusion, coronary tortuosity represents a pathophysiological mechanism for myocardial ischemia in non-obstructive CAD. The coronary tortuosity index could be a reliable and widely applicable tool for the quantification of coronary tortuosity.

Coronary artery tortuosity and mid-term all-cause mortality of patients with ischemia and non-obstructive coronary arteries

Background: Coronary artery tortuosity (CAT) is a frequently encountered angiographic feature of patients with ischemia and non-obstructive coronary arteries (INOCA). However, there is limited data regarding the possible correlation between CAT and all-cause mortality in these patients. Aim: To assess the survival prognostic implications of CAT in INOCA patients and the predictors of all-cause mid-term mortality of these patients. Methods: All consecutive INOCA patients, with preserved ejection fraction evaluated for clinical ischemia by coronary angiography in our department between January 2014 and December 2020 were considered for inclusion. Patients with epicardial coronary artery stenosis ≥ 50%, severe pulmonary hypertension, or decompensated extra cardiac disease were excluded. Eleid classification was used for CAT severity characterization. We assessed all-cause mortality in January 2023. Results: Our sample included 328 INOCA patients. 15.54% died during the mean follow-up of 3.75 ± 1.32 years. 79.88% had CAT. CAT patients were older (65.10±9.09 versus 61.24±10.02 years, p=0.002), and more often female (67.18% versus 31.82%, p<0.001). CAT was inversely correlated with all-cause mid-term mortality (OR 0.35, 95%CI 0.16 - 0.77, p=0.01). CAT severity had no impact on survival. In CAT patients the initial multivariable analysis identified NT-proBNP levels (HR 3.96, p=0.01), diabetes mellitus (DM) (HR 4.76, p=0.003), and atrial fibrillation (HR 2.68, p=0.06) as independent predictors of all-cause mortality. In the final analysis, NT-proBNP and DM were the main independent predictors of survival. Conclusions : In our INOCA cohort, CAT patients were older and more likely female. CAT was inversely correlated with mid-term all-cause mortality. NT-proBNP and DM were the main independent predictors of mortality of CAT patients.

Evaluation of left atrial and left ventricular functions with 3D speckle-tracking echocardiography in patients with coronary artery tortuosity

BACKGROUND

Tortuosity in the coronary arteries is a very common entity encountered during angiography. The effect of coronary artery tortuosity (CAT) on the myocardium has not been completely investigated. The aim of the current study was to assess the effects of CAT on left atrial (LA) and left ventricular (LV) myocardial functions by 3D speckle-tracking echocardiography (3D-STE).

METHODS

Seventy-five patients with CAT and 80 age- and gender-matched controls who proved to have normal coronary angiograms (CAG) were enrolled into the study. Following CAG, the 2D images were obtained first, and then 3D images were obtained for strain analysis.

RESULTS

The LAS-r, LAS-active, and LV-GLS were significantly depressed in the CAT (+) group (p < .001, p < .001, p = .012, respectively). The multivariate regression models demonstrated that LAS-r (p < .001), LAS-active (p = .009), and LV-GLS (p = .024) were found to be independent factors predicting CAT.

CONCLUSION

The current study is the first to focus on the assessing both LA and LV myocardial dynamics in CAT (+) patients by strain echocardiography. The results of our study support the patients with CAT may have subclinical LA and LV myocardial involvements.

Contrast Stress Echocardiography Findings in Myocardial Bridging Compared to Normal Coronary Course, With and Without Coronary Artery Disease

BACKGROUND

Myocardial bridging (MB) correlation with ischemia remains a diagnostic challenge. There is a lack of studies that have assessed MB using contrast stress echo and compared the findings with those in patients demonstrating a normal coronary course, with or without obstructive coronary artery disease (CAD).

METHODS

We evaluated all consecutive patients who underwent contrast stress echocardiography and coronary computed tomography angiography (CCTA) due to suspected symptoms of CAD within 3 months in Parma Hospital. Coronary computed tomography angiography served as the reference standard for detecting MB and obstructive CAD. The patients were divided into 3 groups: (1) MB and no evidence of obstructive CAD (MB group, N = 64), (2) no evidence of obstructive CAD or MB (NoCAD group, N = 135), (3) obstructive CAD without MB (CAD group, N = 68).

RESULTS

The coronary flow velocity reserve in the LAD (CFVR-LAD) was reduced in the MB and CAD groups, measuring 1.91 ± 0.21 and 1.82 ± 0.28, respectively, whereas it was 2.27 ± 0.34 in the NoCAD group (P < .001). The MB and CAD groups exhibited a higher prevalence of reversible myocardial perfusion defects (rMPDs) compared to the NoCAD group (57.8% vs 64.7% vs 3.7%, P < .001). Reversible wall motion abnormalities were frequently observed in the CAD group and rarely found in the MB and NoCAD groups (47.1% vs 18.8% vs 4.4%, P < .001). In multivariable analyses, the presence of MB was independently associated with reduced CFVR-LAD (odds ratio = 14.55; 95% CI, 6.84-30.93; P < .001) and the presence of rMPD (odds ratio = 37.96; 95% CI, 13.49-106.84; P < .001). Patients with deep MB (>2 mm depth) and very deep MB (≥5 mm depth) exhibited significantly greater CFVR-LAD reduction and rMPD than those with superficial MB.

CONCLUSIONS

Myocardial bridging is capable of inducing rMPD and reducing CFVR-LAD similar to obstructive CAD. The depth of the MB correlates with the abnormalities found in the stress echo evaluation. Contrast stress echo may serve as a valuable noninvasive tool for evaluating patients with MB.

The Association of Severe Coronary Tortuosity and Non-Obstructive Coronary Artery Disease

Background and Objectives: There is an increasing interest in the coronary tortuosity as a novel pathophysiological mechanism of ischemia in coronary artery disease without significant obstruction, but there are a lack of studies to confirm this relationship in the clinical setting. The aim of our study was to evaluate the association of severe coronary tortuosity and the potential role of coronary blood supply dominance in the appearance of myocardial ischemia in patients with non-obstructive coronary artery disease (non-CAD), compared to patients with obstructive coronary artery disease (CAD). Materials and Methods: The study enrolled 131 participants (71 male and 60 female), recruited among patients referred to cardiologists due to angina symptoms with ischemic alterations established by cardiac stress tests, as well as those admitted to the hospital for acute coronary syndrome. Results: Mean age of recruited patients was 61.6 (±10.1) years. According to the coronary angiography, they were divided into two groups: non-obstructive and obstructive CAD (77 and 54, respectively). There were significantly more women (61% vs. 24%, p < 0.001) in the non-CAD group. Both tortuous coronary arteries (50.6% vs. 14.8%, p < 0.001) and left coronary dominance (37.7% vs. 16.7%, p = 0.006) were more frequent in the non-CAD group compared to the CAD group. Female sex (OR = 17.516, p = 0.001), tortuous coronary arteries (OR = 7.962, p = 0.006) and left dominance of blood supply were significant predictors for non-CAD. Conclusions: Non-obstructive CAD is common among patients, especially women, who are referred for coronary angiography. Severe coronary artery tortuosity is the strongest independent predictor of non-obstructive CAD, followed by female gender and left coronary dominance.

Novel deep learning method for coronary artery tortuosity detection through coronary angiography

Coronary artery tortuosity is usually an undetected condition in patients undergoing coronary angiography. This condition requires a longer examination by the specialist to be detected. Yet, detailed knowledge of the morphology of coronary arteries is essential for planning any interventional treatment, such as stenting. We aimed to analyze coronary artery tortuosity in coronary angiography with artificial intelligence techniques to develop an algorithm capable of automatically detecting this condition in patients. This work uses deep learning techniques, in particular, convolutional neural networks, to classify patients into tortuous or non-tortuous based on their coronary angiography. The developed model was trained both on left (Spider) and right (45°/0°) coronary angiographies following a fivefold cross-validation procedure. A total of 658 coronary angiographies were included. Experimental results demonstrated satisfactory performance of our image-based tortuosity detection system, with a test accuracy of (87 ± 6)%. The deep learning model had a mean area under the curve of 0.96 ± 0.03 over the test sets. The sensitivity, specificity, positive predictive values, and negative predictive values of the model for detecting coronary artery tortuosity were (87 ± 10)%, (88 ± 10)%, (89 ± 8)%, and (88 ± 9)%, respectively. Deep learning convolutional neural networks were found to have comparable sensitivity and specificity with independent experts' radiological visual examination for detecting coronary artery tortuosity for a conservative threshold of 0.5. These findings have promising applications in the field of cardiology and medical imaging.

Treatment of Highly Angulated Lesions Using SuperCross Microcatheter

Unusually angulated coronary anatomy can decrease the success rate of coronary interventions by hindering successful wiring and equipment delivery. Additionally, due to the technical challenges involved, there is increased risk for complications such as perforations, dissections, stent loss, and equipment entrapment. In this case series, we illustrate the advantages of using angulated microcatheters to facilitate successful treatment of such patients in various clinical scenarios.

Epicardial atherosclerosis and coronary tortuosity in patients with acetylcholine-induced coronary spasm

BACKGROUND

Angina pectoris in the absence of relevant epicardial stenoses is frequently caused by coronary spasm. This mechanism of angina is common yet underdiagnosed in daily clinical practice. The pathophysiology of coronary spasm is complex, multifactorial, and not completely understood. The purpose of this study was to analyze the relationship between macroscopic coronary morphologies and coronary spasm.

METHODS

Epicardial atherosclerosis, coronary vessel tortuosity, coronary aneurysms, and myocardial bridges were analyzed angiographically in 610 patients and a potential association with the result of an intracoronary acetylcholine (ACh) provocation test was investigated.

RESULTS

The comparison showed that angiographic morphologic variations in the coronary arteries are related to the occurrence of coronary spasm. We observed a strong association between the presence of epicardial atherosclerosis and epicardial spasm [87 patients of 179 with epicardial spasm had epicardial atherosclerosis (49%) vs. 45 patients of 172 with microvascular spasm (26%) vs. 89 patients of 259 with negative/inconclusive ACh test (36%); P < 0.005]. Moreover, we found a higher frequency of coronary tortuosity in patients with microvascular spasm [99 patients of 172 with microvascular spasm had at least moderate coronary tortuosity (58%) vs. 76 patients of 179 with epicardial spasm (43%) vs. 126 patients of 259 with negative/inconclusive ACh test (49%); P = 0.017]. Multivariable analysis revealed epicardial atherosclerosis (<50% stenosis) on coronary angiography as a predictor for epicardial spasm (OR, 2.096; 95% CI, 1.467-2.995; P < 0.0005). Female sex (OR, 5.469; 95% CI, 3.433-8.713; P < 0.0005), and exertional angina (OR, 2.411; 95% CI, 1.597-3.639; P < 0.0005) were predictors of microvascular spasm in multivariable analysis.

CONCLUSION

In angina patients with no obstructive coronary artery disease, epicardial atherosclerosis is associated with ACh-induced epicardial coronary spasm. Moreover, coronary microvascular spasm is more prevalent in female patients and those with exertional angina. Our results provide insights into the relationship between coronary morphology and coronary vasomotor function.

Coronary Tortuosity as a New Phenotype for Ischemia without Coronary Artery Disease

BACKGROUND

Coronary arteries tend to be more tortuous than other arteries and follow the repeated flexion and relaxation movements that occur during the cardiac cycle. Coronary tortuosity (CorT) leads to changes in coronary flow with a reduction in distal perfusion pressure, which could cause myocardial ischemia.

OBJECTIVE

To assess the association between CorT and myocardial ischemia.

METHODS

Between January 2015 and December 2017, 57 patients with angina and nonobstructive coronary artery disease detected by invasive coronary angiography (ICA) were retrospectively enrolled. Angiographic variables were analyzed to assess the presence and degree of tortuosity and correlated with their respective vascular territories on stress myocardial perfusion imaging (MPI). CorT was defined as coronary arteries with three or more bend angles ≤90°, measured during diastole. Statistical significance was determined at the 5% level.

RESULTS

A total of 17 men and 40 women were enrolled (mean age 58.3 years). CorT was observed in 16 patients (28%) and in 24 of 171 arteries. There was a significant association between CorT and ischemia when analyzed per artery (p<0.0001). The angiographic factor most associated with ischemia was the number of bend angles in an epicardial artery measured at systole (p=0.021).

CONCLUSION

This study showed an association of CorT and myocardial ischemia in patients with unobstructed coronary arteries and angina. An increased number of coronary bend angles measured by angiography during systole was related to ischemia.

Relationship between Coronary Artery Tortuosity and Cardiorespiratory Fitness in Patients without Obstructed Coronaries

OBJECTIVE

This study aimed to analyze the relationship between cardiorespiratory fitness (CRF) and the increasing severity of coronary artery tortuosity (CAT) in patients with non-stenosed coronaries.

METHODS

A total of 396 patients who underwent coronary angiography and cardiopulmonary exercise testing (CPET) between August 2020 and July 2021 were included in this single-center retrospective study after excluding patients with significant coronary artery disease (≥50% stenosis). Patients were divided into two groups: no or mild coronary artery tortuosity (N/M-CAT) and moderate to severe coronary artery tortuosity (M/S-CAT) and laboratory electrocardiographic, echocardiographic, and CPET parameters were compared between two groups.

RESULTS

M/S-CAT was found in 46.9% of the study participants, with 66.7% being women. M/S-CAT was significantly associated with advanced age (P=0.014) and females (P=0.001). Diastolic dysfunction parameters, E velocity (P=0.011), and E/A ratio (P=0.004) also revealed significant differences between the M/S-CAT group and N/M-CAT group. VO₂@peak (1.22±0.39 vs. 1.07±0.39, P<0.01) and VO₂@AT (0.77±0.22 vs. 0.71±0.21, P=0.017) were significantly lower in the M/S-CAT group than in the N/M-CAT group. Multivariate logistic regression analysis identified females (OR=0.448; 95% CI, 0.296-0.676; P=0.000) and E/A ratio (OR=0.307; 95% CI, 0.139-0.680; P=0.004) to be independent risk factors of M/S-CAT and showed no association of CPET parameters to M/S-CAT.

CONCLUSION

The results indicate that increasing severity of CAT is strongly associated with female gender and E/A ratio and is not directly correlated with decreasing CRF. Further research with a larger patient population and a longer follow-up time is required to fully comprehend the impact of CAT on CRF.

Pathological Roles of Oxidative Stress in Cardiac Microvascular Injury

Cardiac microvascular injury can be a fundamental pathological process that causes high incidence cardiovascular diseases such heart failure, diabetic cardiomyopathy, and hypertension. It is also an independent risk factor for cardiovascular disease. Oxidative stress is a significant pathological process in which the body interferes with the balance of the endogenous antioxidant defense system by producing reactive oxygen species, leading to property changes and dysfunction. It has been demonstrated that oxidative stress is one of the major causes of cardiac microvascular disease. Therefore, additional investigation into the relationship between oxidative stress and cardiac microvascular injury will direct clinical management in the future. In order to give suggestions and support for future in-depth studies, we give a basic overview of the cardiac microvasculature in relation to physiopathology in this review. We also summarize the role of oxidative stress of mitochondrial and non-mitochondrial origin in cardiac microvascular injury and related drug studies.

Non-electrocardiography- and electrocardiography-gated computed tomography angiography for the evaluation of feline coronary arteries

Objectives

Few studies have directly compared the clinical feasibility of electrocardiography-gated and non-electrocardiography-gated multidetector computed tomography for evaluating coronary arteries in veterinary medicine. We aimed to characterize and visualize feline coronary arteries using these two imaging modalities. We hypothesed that ECG-gated MDCT is superior to or advantageous to the non-ECG gated.

Methods

This prospective, controlled, comparative pilot study examined six client-owned cats (five clinically normal and one with hypertrophic cardiomyopathy) using non-electrocardiography-gated and retrospective electrocardiography-gated scans. Optimal non-electrocardiography scan timing or electrocardiography-gated R-R reconstruction interval for coronary artery visualization was determined. The degree of opacification and sharpness of proximal coronary branches was subjectively graded; coronary dominance, left coronary artery branching types, and the diameter and length of coronary artery branches were also assessed.

Results

Non-electrocardiography-gated images provided the least information on the bilateral coronary artery ostium and proximal segments, while electrocardiography-gated images clarified the detailed course of the main coronary branches at diastole in all cats. The degree of opacification and sharpness of the coronary arteries was subjectively evaluated as good/excellent in all cats. Coronary dominance (left: four; right: two) and left coronary artery branching types (three different patterns, two additional tortuous branches) varied. Body weight and sex were not significantly associated with coronary artery length or diameter. Vertebral heart score positively correlated with the right coronary artery and negatively correlated with the left main coronary artery.

Clinical significance

Electrocardiography-gated multidetector computed tomography provides images with adequate resolution to identify the anatomy of feline coronary arteries. Detailed morphological knowledge of feline coronary vessels will enable novel diagnostic and therapeutic methods in veterinary medicine.

Effect of coronary tortuosity on invasive physiology

We present a case of angina, where extreme coronary tortuosity affected invasive physiology interpretation. Extreme coronary tortuosity may lower fractional flow reserve and instantaneous wave-free ratio. Therefore, invasive physiology can be misleading in this setting, when used to evaluate stenosis significance, or when used post-percutaneous coronary (PCI) intervention for physiology guided stent optimisation.

Influence of myocardial bridge on atherosclerotic plaque distribution and characteristics evaluated by near-infrared spectroscopy intravascular ultrasound

BACKGROUND

This study aims to clarify whether myocardial bridge (MB) could influence atherosclerotic plaque characteristics assessed using near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS) imaging.

METHODS

One hundred and sixteen patients who underwent percutaneous coronary intervention (PCI) using NIRS-IVUS imaging were included. MB was defined as an echo-lucent band surrounding left anterior descending artery (LAD). In MB patients, LAD was divided into three segments: proximal, MB, and distal segments. In non-MB patients, corresponding three segments were defined based on the average length of the above segments. Segmental maximum plaque burden and lipid content derived from NIRS-IVUS imaging in the section of maximum plaque burden were evaluated in each segment. Lipid content of atherosclerotic plaque was evaluated as lipid core burden index (LCBI) and maxLCBI_4mm. LCBI is the fraction of pixels indicating lipid within a region multiplied by 1000, and the maximum LCBI in any 4-mm region was defined as maxLCBI_4mm.

RESULTS

MB was identified in 42 patients. MB was not associated with maximum plaque burden in proximal segment. LCBI and maxLCBI_4mm were significantly lower in patients with MB than those without in proximal segment. Multivariable analysis demonstrated both MB and maximum plaque burden in proximal segment to be independent predictors of LCBI in proximal segment.

CONCLUSIONS

Lipid content of atherosclerotic plaque assessed by NIRS-IVUS imaging was significantly smaller in patients with MB than those without. MB could be considered as a predictor of lipid content of atherosclerotic plaque when assessed by NIRS-IVUS imaging.

Stress-echocardiography or coronary computed tomography in suspected chronic coronary syndrome after the 2019 European Guidelines? A practical guide

Stress-echocardiography can rightly be considered one of the champions of cardiac functional imaging, thanks to its real-time imaging, high temporal resolution, high safety and very low cost. When stress-echocardiography is performed at top technical quality, hence taking advantage of ultrasound contrast media for endocardial border delineation at least for suboptimal cases, subjectivity is minimized, and with the routine use of coronary flow reserve measurement (left anterior descending coronary artery, stress/rest ratio reduced or normal, i.e. <>2.0) diagnostic sensitivity is strengthened. The true competitor of any type of functional imaging, stress-echocardiography included, is nowadays coronary computed tomography angiography, which is instead a diagnostic method directly, noninvasively assessing coronary anatomy, apparently the holy grail for any cardiologist. The new 2019 Guidelines on chronic coronary syndrome of the European Society of Cardiology change the existing landscape and clinical practice, while they probably cannot clarify which type of test, functional or anatomic, should be first chosen in different clinical scenarios of suspected chronic coronary syndrome. We review the existing data and the authors' personal view in order to assess how functional stress-echocardiography compares with coronary computed tomography angiography regarding three main aspects: diagnosis of coronary artery disease, guidance of therapy (coronary revascularization versus medical therapy) and risk stratification.

Impact of coronary artery tortuosity in ischemic and non-ischemic cardiovascular pathology

The aim of this paper was to review based on the existing literature the impact of coronary artery tortuosity on coronary pathology. Primarily, an attempt was made to establish the implication of coronary tortuosity as a physio-pathological mechanism of inducing ischemia in patients with non-obstructive coronary artery disease (CAD). Because the prevalence of tortuosity is higher in severe hypertensive patients, a second purpose of this paper was to review this association by understanding the physio-pathological processes and fluid dynamics in hypertrophic heart. Particularly, the effect of coronary tortuosity on systolic function with reference to longitudinal function and ventricular relaxation was addressed. Finally, the technical difficulties imposed by coronary tortuosity to percutaneous coronary interventions were discussed.

A Hemodynamic Comparison of Myocardial Bridging and Coronary Atherosclerotic Stenosis: A Computational Model With Experimental Evaluation

Myocardial bridging (MB) and coronary atherosclerotic stenosis can impair coronary blood flow and may cause myocardial ischemia or even heart attack. It remains unclear how MB and stenosis are similar or different regarding their impacts on coronary hemodynamics. The purpose of this study was to compare the hemodynamic effects of coronary stenosis and MB using experimental and computational fluid dynamics (CFD) approaches. For CFD modeling, three MB patients with different levels of lumen obstruction, mild, moderate, and severe were selected. Patient-specific left anterior descending (LAD) coronary artery models were reconstructed from biplane angiograms. For each MB patient, the virtually healthy and stenotic models were also simulated for comparison. In addition, an in vitro flow-loop was developed, and the pressure drop was measured for comparison. The CFD simulations results demonstrated that the difference between MB and stenosis increased with increasing MB/stenosis severity and flowrate. Experimental results showed that increasing the MB length (by 140%) only had significant impact on the pressure drop in the severe MB (39% increase at the exercise), but increasing the stenosis length dramatically increased the pressure drop in both moderate and severe stenoses at all flow rates (31% and 93% increase at the exercise, respectively). Both CFD and experimental results confirmed that the MB had a higher maximum and a lower mean pressure drop in comparison with the stenosis, regardless of the degree of lumen obstruction. A better understanding of MB and atherosclerotic stenosis may improve the therapeutic strategies in coronary disease patients and prevent acute coronary syndromes.

Impact of Coronary Artery Tortuosity on Outcomes Following Stenting: A Pooled Analysis From 6 Trials

OBJECTIVES

The authors sought to determine whether coronary artery tortuosity negatively affects clinical outcomes after stent implantation.

BACKGROUND

Coronary artery tortuosity is a common angiographic finding and has been associated with increased rates of early and late major adverse events after balloon angioplasty.

METHODS

Individual patient data from 6 prospective, randomized stent trials were pooled. Outcomes at 30 days and 5 years following percutaneous coronary intervention of a single coronary lesion were analyzed according to the presence or absence of moderate/severe vessel tortuosity, as determined by an angiographic core laboratory. The primary endpoint was target vessel failure (TVF) (composite of cardiac death, target vessel-related myocardial infarction [TV-MI], or ischemia-driven target vessel revascularization [ID-TVR]).

RESULTS

A total of 6,951 patients were included, 729 of whom (10.5%) underwent percutaneous coronary intervention in vessels with moderate/severe tortuosity. At 30 days, TVF was more frequent in patients with versus without moderate/severe tortuosity (3.8% vs. 2.4%; hazard ratio [HR]: 1.64; 95% confidence interval [CI]: 1.09 to 2.46; p = 0.02), a difference driven by a higher rate of TV-MI. At 5 years, TVF remained increased in patients with moderate/severe tortuosity (p = 0.003), driven by higher rates of TV-MI (p = 0.003) and ID-TVR (p = 0.01). Definite stent thrombosis was also greater in patients with versus without moderate/severe tortuosity (1.9% vs. 1.0%; HR: 1.86; 95% CI: 1.02 to 3.39; p = 0.04). After adjustment for baseline covariates, moderate/severe vessel tortuosity was independently associated with TV-MI and ID-TVR at 5 years (p = 0.04 for both).

CONCLUSIONS

Stent implantation in vessels with moderate/severe coronary artery tortuosity is associated with increased rates of TVF due to greater rates of TV-MI and ID-TVR.

Myocardial bridges: A meta-analysis

Myocardial bridges are anatomical entities characterized by myocardium covering segments of coronary arteries. In some patients, the presence of a myocardial bridge is benign and is only incidentally found on autopsy. In other patients, however, myocardial bridges can lead to compression of the coronary artery during systolic contraction and delayed diastolic relaxation, resulting in myocardial ischemia. This ischemia in turn can lead to myocardial infarction, ventricular arrhythmias and sudden cardiac death. Myocardial bridges have also been linked to an increased incidence of atherosclerosis, which has been attributed to increased shear stress and the presence of vasoactive factors. Other studies however, demonstrated the protective roles of myocardial bridges. In this study, using systematic review and a meta-analytical approach we investigate the prevalence and morphology of myocardial bridges in both clinical imaging and cadaveric dissections. We also discuss the pathophysiology, clinical significance, and management of these anatomical entities.

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.

Relationship between sclerostin and coronary tortuosity in postmenopausal females with non-obstructive coronary artery disease

BACKGROUND

Coronary tortuosity (CT) is commonly encountered in postmenopausal females and is usually present without obstructive lesions. Circulating sclerostin levels are elevated in postmenopausal females. In view of sclerostin's vasculoprotective effect, we aimed to find possible association between circulating sclerostin and CT.

METHOD

We prospectively enrolled 273 consecutive postmenopausal females with non-obstructive coronary artery disease diagnosed by coronary angiography. Presence and severity (by tortuosity score) of CT as well as serum sclerostin levels were assessed for each patient.

RESULTS

Patients with CT (128, 47% of study group) were significantly older (P < 0.001), with higher prevalence of hypertension (P = 0.001) and had significantly higher levels of both sclerostin (P < 0.001) and hs-CRP (P = 0.001). Multivariate binary logistic regression revealed that the presence of CT (dependent variable) was associated with high sclerostin level (OR 8.9, 95% CI: 4.9-16.2, P < 0.001). Using ROC curve analysis, Sclerostin at a cut-off value of >650 pg/ml was found to be associated with presence of CT (AUC 0.69, 95% CI: 0.61-0.75, P < 0.001) with sensitivity and specificity of 75% and 72.4%, respectively. Using Pearson's correlation analysis, significant positive correlation between sclerostin and severity of CT was found (r = 0.29, P = 0.001).

CONCLUSION

High circulating sclerostin is associated with the presence and severity of CT in postmenopausal females. This may add to the literature on the incompletely understood pathogenesis of CT.

Coronary flow reserve and microcirculatory resistance in patients with coronary tortuosity and without atherosclerosis

Objective

Coronary tortuosity may affect epicardial coronary arterial blood flow. This study aimed to investigate the effect of coronary tortuosity on coronary flow reserve and the coronary microcirculation in patients without apparent coronary atherosclerosis.

Methods

Prospective patients (n = 8, 3 men, mean age: 58 ± 6.0 years) with coronary tortuosity and without apparent coronary atherosclerosis were enrolled. Coronary tortuosity was defined by the finding of ≥three bends (defined as a ≥45° change in vessel direction) along the main trunk of the left anterior descending artery or left circumflex artery. Coronary flow reserve and the index of microcirculatory resistance were measured by the thermodilution technique.

Results

A total of eight coronary arteries with coronary tortuosity were analyzed. The mean fractional flow reserve was 0.98 ± 0.007. The mean coronary flow reserve was 1.5 ± 0.3, which is much lower than that in the normal coronary artery as reported in the literature. The mean index of microcirculatory resistance was 26.7 ± 2.3, which is much higher than that in the normal coronary artery.

Conclusions

Coronary tortuosity is associated with decreased coronary flow reserve and an increased index of microcirculatory resistance.

Trial registration: This study is registered at the Chinese Clinical Trial Registry, NCT No: ChiCTR2000033671

Assessment of Myocardial Perfusion by Angiographic Methods in Tortuous Coronary Arteries

The relationship between coronary tortuosity (CorT) and tissue-level myocardial perfusion is not clear. We investigated tissue perfusion in myocardial territories supplied by tortuous coronary arteries. Among patients who had undergone coronary angiography, patients with reported CorT, those with ≥1 coronary artery were included in the study group (100 patients). The control group included patients with normal coronary arteries (100 patients). Thrombolysis In Myocardial Infarction frame count (TFC) and myocardial blush grade (MBG) were calculated for each coronary artery. Mean TFC was significantly higher in tortuous right coronary artery (RCA), left anterior descending (LAD) artery, and circumflex (Cx) artery compared to their non-tortuous counterparts (28.81 ± 6.463 vs 21.94 ± 3.328, P = .009; 43.28 ± 5.698 vs 36.17 ± 3.875, P = .006; 29.35 ± 4.111 vs 23.821 ± 2.639; P < .001, respectively). Mean MBG was also significantly lower in tortuous RCA, LAD, and Cx, compared to their normal counterparts (2.78 ± 0.417 vs 2.98 ± 0.155, P < .001; 2.74 ± 0.483 vs 2.97 ± 0.164, P < .001; 2.92 ± 0.277 vs 2.99 ± 0.110, P < .001, respectively). For each tortuous coronary artery, TFC was similar for every MBG category. Tortuous coronary arteries have higher TFC and lower MBG, suggesting impaired epicardial and microvascular coronary flow, when compared to normal coronary arteries.

Coronary tortuosity affects left ventricular myocardial functions: a 3D-speckle tracking echocardiography study

Coronary artery tortuosity (CAT) is a common finding in coronary angiography, and is defined as three fixed bends during both systole and diastole in at least one epicardial coronary artery, with each bend showing a 45° change in vessel direction. The impact of CAT on the myocardial deformation has not been completely evaluated using 3D-STE. As a result of this, we aimed to assess the effects of CAT on LV functions using 3D-STE in the present study. Eighty-two patients with CAT and 80 age- and gender-matched controls who proved to have normal coronary angiograms were enrolled into the study. 3D-STE was performed and LV-GLS, LV-GCS, LV-GAS, and LV-GRS were obtained for every patient after coronary angiography. The LV-GLS was significantly depressed in the CAT ( +) group than in the control group (p = 0.001). ROC analysis was performed to find out ideal LV-GLS cut off value to predict the presence of CAT. A LV-GLS value of > - 17 has 81.3% sensitivity, 56.7% specificity to detect the presence of CAT. The present study is the first to focus on the assessing LV myocardial functions in patients with CAT by 3D-STE. CAT has a considerable negative effect on LV myocardial longitudinal deformation as evaluated by 3D strain parameters. Our results support that patients with CAT may have subclinical LV longitudinal deformation abnormalities even though they are apparently healthy.

The significant coronary tortuosity and atherosclerotic coronary artery disease; What is the relation?

Introduction: Although coronary tortuosity is relatively common in coronary angiograms, there is much debate over the significance of this anatomical variation. So in this study the relation between significant coronary tortuosity (SCT) and coronary artery disease (CAD) was examined.

Methods: The cross-sectional study included 737 patients (57% male) who were admitted to the hospital for a coronary angiography, based on their symptoms or non-invasive imaging. Coronary arteries defined as SCT are in the presence of either ≥3 consecutive curvatures of 90◦ to 180◦ or ≥2 consecutive curvatures of ≥180◦ measured at the end-diastole, in a major epicardial coronary artery ≥2 mm in diameter.

Results: 29.17% of the patients had SCT of which females (64.7% vs. 34.1%, P < 0.001) and higher aged persons (62.9±8.4 vs. 57.8±10.7 years ± SD; P < 0.001) were significantly associated with SCT compared to non-SCT. Left anterior descending artery (LAD), left circumflex artery (LCX) and right coronary artery (RCA) with SCT in comparison to non-SCT, had lesser probability of CAD with stenosis severity of ≥50% (34.5% vs. 46.1%; P = 0.019 and 17.7% vs. 31.1%; P = 0.001 and 27.9% vs. 43.5%; P = 0.013 respectively) and also had significant lower Gensini scores (4.1±5.3 vs. 8.4±11.9; P = 0.011; 2.1±3.4 vs. 5.2±9.5; P = 0.01 and 1.2±1.9 vs. 5.03±8.9; P < 0.001 respectively) but higher TIMI frame count (15.7±5.3 vs. 11.9±4.6; P < 0.001 and 17.1±4.4 vs. 12.7±4.4; P < 0.001 and 15.2±3.9 vs. 11.6±4.8; P < 0.001 respectively).

Conclusion: SCT is negatively correlated with CAD and there is a significant association between SCT and reduced coronary flow rate.

Validity of tortuosity severity index in chest pain patients with abnormal exercise test and normal coronary angiography

BACKGROUND

Coronary tortuosity (CT) had different definitions and scores in literature with unclear pathophysiological impact.

OBJECTIVES

To study degree of CT and it's relation to ischemic changes in patients with angina but normal coronary angiography (CA).

METHODS

We conducted a prospective study at University hospitals between May 2016 and January 2017. We included 200 consecutive patients who underwent CA due to chest pain assumed to be of cardiac origin, and their CA was normal (no diameter stenosis >30%, nor myocardial bridging). Patients were prospectively divided into 2 groups based on the presence (n = 113) or absence (n = 87) of ischemic changes during stress study and compared for clinical, echocardiographic and CA characteristics. A newly proposed Tortuosity Severity Index (TSI) was developed into significant (mild/moderate CT with more than 4 curvatures in total, or severe/extreme CT with any number of curvatures) or not significant TSI (mild CT with curvatures less than or equal to 4 curvatures in total).

RESULTS

Patients with ischemic changes had the highest rate of CT (76.5 vs 18%, p = 0.004) compared to those without. CT mostly affects the left anterior descending (LAD) coronary artery in mid and distal segments. Females, elderly, and hypertensives with left ventricular hypertrophy were strongly related to CT. Multivariate logistic regression analysis identified CT with significant TSI as the only predictor of ischemic changes in these patients (OR = 6.2, CI = 2.5-15.3, P = <0.001).

CONCLUSIONS

Coronary tortuosity is a strong predictor of anginal pain among patients with normal CA, despite positive stress study. This finding is more pronounced among elderly, hypertensive female patients.

Coronary tortuosity is negatively correlated with coronary atherosclerosis

Objective

The impact of coronary tortuosity on coronary atherosclerosis remains unclear. This study was performed to determine to the relationship between coronary tortuosity and the presence of coronary atherosclerosis.

Methods

Tortuosity and the presence of coronary atherosclerosis in the main coronary arteries were evaluated. The coronary artery was divided into non-tortuous and tortuous segments. The incidence of coronary atherosclerosis between the two segments was compared.

Results

The prevalence of coronary atherosclerotic stenosis was significantly lower in the tortuous than non-tortuous segment.

Conclusion

The prevalence of coronary atherosclerotic stenosis is lower in the coronary tortuous than non-tortuous segment, indicating that coronary tortuosity might be considered a protective factor for atherosclerosis.

Two-dimensional speckle-tracking echocardiographic evaluation of the longitudinal deformation of the left ventricular myocardium in patients with severe coronary artery tortuosity

PURPOSE

Coronary artery tortuosity (CAT) is an anatomical condition in which epicardial coronary arteries have abnormal curves or spiral courses. Although correlated with higher rates of positive stress test, its effects on the myocardial function remain to be clearly defined.

METHODS

We included in this cross-sectional study and evaluated with 2D speckle-tracking echocardiography 40 consecutive patients admitted to our hospital for selective coronary angiography which showed severe CAT without significant epicardial coronary artery stenosis, and 40 consecutive subjects matched for age, hypertension, and diabetes in whom selective coronary angiography showed neither CAT nor significant epicardial coronary artery stenosis.

RESULTS

Systolic strain, strain rate, and early and late diastolic strain rates were not significantly different between the 2 groups, even after adjustment for potential confounding variables.

CONCLUSION

The 2D speckle-tracking echocardiography-derived indices of longitudinal deformation of the left ventricular myocardium were not significantly different between the patients with severe CAT and controls.

Coronary tortuosity is associated with an elevated high-sensitivity C-reactive protein concentration and increased risk of ischemic stroke in hypertensive patients

Objective

The clinical implication of coronary tortuosity is unclear. The present study was conducted to determine the relationships between coronary tortuosity and the high-sensitivity C-reactive protein (hs-CRP) concentration and between coronary tortuosity and cerebrovascular accident in hypertensive patients without coronary artery disease.

Methods

In total, 236 patients with normal coronary angiography findings were categorized into 3 different groups: control participants (n = 58), who had neither hypertension nor coronary tortuosity; patients with hypertension but no coronary tortuosity (H-NCT group, n = 93); and patients with both hypertension and coronary tortuosity (H-CT group, n = 85). The hs-CRP concentration was measured in every patient, and 168 hypertensive patients were followed up for at least 2 years to check for the development of cerebrovascular accident.

Results

The hs-CRP concentration was significantly higher in the H-CT group than in the control and H-NCT groups (4.33 ± 3.15 vs. 1.52 ± 1.31 and 2.31 ± 2.09 mg/L, respectively). The incidence of lacunar infarction was higher in the H-CT than H-NCT group during the follow-up.

Conclusions

Hypertensive patients with coronary tortuosity have a higher serum hs-CRP level concentration and have a higher incidence of lacunar infarction than hypertensive patients without coronary tortuosity.

Stress echocardiography pattern: a promising noninvasive test for detection of myocardial bridging with haemodynamic relevance

: We reported a case of a young athlete with an underlying myocardial bridging in the left anterior descending coronary artery (LAD) causing myocardial ischemia suspected by contrast exercise stress echocardiography and confirmed by computed tomography coronary angiography. Our report demonstrated that a specific stress echocardiography pattern consisting of reversible focal buckling in the end-systolic to early-diastolic motion of the septum may suggest the presence of an underlying myocardial bridging in the LAD.

Coronary capillary blood flow in a rat model of congestive heart failure

The aim of this study was to explore the role of abnormal coronary microvasculature morphology and hemodynamics in the development of congestive heart failure (CHF). CHF was induced in rats by aortic banding, followed by ischemia-reperfusion and later aortic debanding. Polymerized casts of coronary vasculature were imaged under a scanning electron microscope (SEM). Matrix Laboratory (MATLAB) software was used to calculate capillary structure index (CSI), a measure of structural alignment also called mean vector length (MVL), for 93 SEM images of coronary capillaries (CSI→1 perfect linearity; CSI→0 circular disarray). CSI was incorporated as a constant to represent tortuosity and nonlaminar flow in Poiseuille's equation to estimate the differences in capillary blood flow rate, velocity, and resistance for CHF vs.

CONTROL

The morphology of CHF capillaries is significantly disordered and tortuous compared with control (CSI: 0.35 ± 0.02 for 61 images from 7 CHF rats; 0.58 ± 0.02 for 32 images from 7 control rats; P < 0.01). Estimated capillary resistance in CHF is elevated by 173% relative to control, while blood flow rate and blood velocity are 56 and 43% slower than control. Capillary resistance increased 67% due to the significantly narrower capillary diameter in CHF, while it increased an additional 105% due to tortuosity. The significant structural abnormalities of CHF coronary capillaries may drastically stagnate hemodynamics in myocardium and increase resistance to blood flow. This could play a role in the development of CHF. NEW & NOTEWORTHY In the present study, coronary capillary tortuosity was measured by applying Matrix Laboratory software to scanning electron microscope images of capillaries in a rat model of congestive heart failure. Stagnant blood flow in coronary capillaries may play a role in the development of congestive heart failure. The application of computer modeling to histological and physiological data to characterize the hemodynamics of coronary microcirculation is a new area of study.

Myocardial Bridging: A Meta-Analysis of Prevalence

The main objective of this article was to analyze prevalence data about myocardial bridging (MB) in published studies. To this purpose, we performed a meta-analysis of studies published in English literature that contained data about the prevalence of MB and its anatomical characteristics. The overall prevalence was 19% (CI: 17-21%); autopsy studies revealed an overall prevalence of 42% (CI: 30-55%), CT studies 22% (CI: 18-25%), and coronary angiography 6% (CI: 5-8%). Most bridges were located on the left anterior descending artery (82% overall, 63% on autopsy studies), had a mean thickness of 2.47 mm and a mean length of 19.3 mm. In conclusion, autopsy studies should be the gold standard in evaluating the actual prevalence of myocardial bridges, while in vivo high-resolution CT scanning should be preferred to coronary angiography studies.

Increased Coronary Tortuosity Is Associated with Increased Left Ventricular Longitudinal Myocardial Shortening

BACKGROUND

The mechanistic basis for tortuosity of the coronary arteries (TCA) is unclear. The aim of this study was to test the hypothesis that the relative degree of systolic longitudinal shortening of the left ventricle that deforms coaxially oriented coronary arteries is associated with TCA.

METHODS

Adult subjects undergoing coronary angiography and comprehensive echocardiography within 3 months were classified dichotomously as with (n = 32) or without (n = 42) TCA defined on the basis of number and severity of coronary angles. Systolic left ventricular (LV) longitudinal deformation was determined by mitral annular plane systolic excursion (MAPSE) from both B-mode displacement and tissue Doppler time-velocity integral; data were indexed to LV diastolic long-axis length.

RESULTS

There were no differences between groups with respect to age, gender, hypertension, or coronary artery disease. Patients with TCA had significantly (P < .01) lower LV mass index and a shorter total LV diastolic long-axis length (mean, 8.3 ± 1.9 vs 9.1 ± 2.2 cm; P < .01). Despite having a shorter length, those with TCA had greater MAPSE by both methods. MAPSE normalized to diastolic length was significantly greater (P < .01) in those with TCA, which remained the case after excluding subjects with reduced LV ejection fraction. Multiple linear regression found that lateral annular MAPSE had the largest effect size, with a 13-fold increase in likelihood for TCA for every 0.1 of normalized MAPSE.

CONCLUSIONS

TCA is not associated with increased LV mass but rather with smaller hearts that have greater relative longitudinal shortening of the left ventricle. This finding suggests that TCA could represent an adaptive response to longitudinal systolic distortion of coaxially oriented coronary arteries that dynamically produce shear stresses associated with expansive coronary remodeling.

Gender differences in the prevalence of coronary artery tortuosity and its association with coronary artery disease

Background

Little is known about the significance of severe coronary tortuosity (SCT) despite it being a relatively common finding on coronary angiography. We examined whether the presence of tortuosity was influenced by gender or cardiac risk factors.

Methods and results

We examined 870 patients (Men = 589, Women = 281) who presented to Westmead Hospital, Sydney, Australia for invasive coronary angiography for the assessment of chest pain due to suspected CAD. Female gender and age were significantly associated with SCT (p < 0.001 for age) with 45.2% of women having SCT as opposed to 19.7% of men (p < 0.001). Men with SCT had lower Extent scores only compared than those without tortuosity (22.4 vs. 32.4, p = 0.003). However, women with SCT had less severe coronary artery disease than those with no SCT as measured by both the Extent score (12.4 vs. 19.1, p = 0.03) and Gensini score (10.4 vs. 15.5, p = 0.02).

Conclusion

There is a significant relationship between coronary artery tortuosity and gender. Women with severe tortuosity are more likely to have normal coronary arteries or less severe disease than men despite presenting with chest pain.

Relationship between coronary tortuosity and plateletcrit coronary tortuosity and plateletcrit

Background

Coronary tortuosity (CorT) is a common angiographic finding and may be associated with myocardial ischaemia, even without coronary artery disease. Platelets play a crucial role in inflammatory and thrombotic processes and the physiopathology of cardiovascular disease. Larger platelets are more active enzymatically and have higher thrombotic ability compared to smaller platelets. Plateletcrit (PCT) provides complete information on total platelet mass. We aimed to evaluate the relationship between CorT and PCT in patients with chronic stable angina.

Methods

The medical records of consecutive patients who underwent coronary angiography from January 2013 to January 2016 were retrospectively reviewed for CorT. CorT and clinical, echocardiographic, haematological and biochemical parameters were evaluated. Taking into consideration the inclusion criteria, 106 patients with CorT and 108 with normal coronary angiographies (control group) were included in the study. CorT was defined as three fixed bends during both systole and diastole, with each bend ≥ 45°.

Results

The median PCT, mean platelet volume (MPV), platelet:large-cell ratio (P-LCR), neutrophil:lymphocyte ratio (NLR) and platelet:lymphocyte ratio (PLR) of the CorT group were significantly higher than those of the control group (0.26 ± 0.02 vs 0.2 ± 0.03%, p < 0.001; 10.6 ± 0.14 vs 9.6 ± 0.65 fl, p < 0.001; 29.3 ± 6.7 vs 23.4 ± 5.1, p < 0.001; 2.3 ± 1 vs 1.47 ± 0.48, p < 0.001; 1.28 ± 0.5 vs 0.82 ± 0.23, p < 0.001, respectively). The incidence of diabetes mellitus, hypertension and female gender were significantly higher in the CorT group (18.9 vs 1.9%, p < 0.001, 90.6 vs 50%, p < 0.001, 70.8 vs 44.4%, p < 0.001, respectively). Multivariate logistic regression analysis revealed age, hypertension, diabetes mellitus and plateletcrit were independently associated with CorT.

Conclusion

CorT was associated with increased PCT, MPV, P-LCR, NLR and PLR, even in the absence of coronary artery disease. Age, hypertension, diabetes mellitus and plateletcrit were independently associated with CorT.

Tortuosity, Recurrent Segments, and Bridging of the Epicardial Coronary Arteries in Patients With the Takotsubo Syndrome

Myocardial bridging (MB) and a long recurrent wraparound left anterior descending artery (wrap-LAD) are coronary anatomic variants that have been recently suggested to be associated with takotsubo syndrome (TS). Until now, coronary artery tortuosity (CAT) has never been investigated in this setting. Our study sought to evaluate the prevalence of the aforementioned anatomic variants in a large population with TS. In this retrospective angiographic study, 109 patients with TS were compared with 109 age- and gender-matched subjects without coronary artery disease, valve heart disease, or cardiomyopathy. CAT was identified by ≥3 consecutive curvatures ≥90° (criteria 1) or by ≥2 consecutive curvatures ≥180° (criteria 2). Wrap-LAD was defined if any part of the vessel outreached the apex of the left ventricle and MB as the presence of a milking effect or a step-up and step-down phenomenon. An anatomic variant was found in 79 patients with TS (72%) and in 48 controls (44%) (p <0.001). CAT in at least 1 vessel (criteria 1: 49% vs 20%, p <0.001; criteria 2: 38% vs 13%, p <0.001), ≥2 vessels (criteria 2: 14% vs 3%, p = 0.005), and wrap-LAD (41% vs 27%, p = 0.02) were significantly more frequent in patients with TS than in controls. The prevalence of MB (9% vs 5%, p = 0.18) did not differ between groups. In conclusion, CAT and wrap-LAD have higher prevalence in patients with TS than in matched controls. These findings could support the hypothesis that anatomic variants might act as potential pathogenic substrates in TS.

Multimodality Imaging in the Assessment of the Physiological Significance of Myocardial Bridging

In myocardial bridging (MB) a segment of the coronary artery is covered by the myocardium. MB can be seen as a systolic compression by invasive coronary angiography (ICA) or as an intramural course by computed tomography angiography (CTA). Intramural course is a common incidental finding in CTA studies. Only minority of the bridging segments are associated with systolic compression causing a possible impairment of myocardial perfusion. The relationship between myocardial blood flow and MB is complex and poorly evaluated by anatomic imaging. Furthermore, provocation tests are frequently needed to uncover systolic compression. Fractional flow reserve can be used to assess the hemodynamic significance of MB. Nuclear perfusion imaging can demonstrate flow abnormalities associated with MB. Stress echocardiography can demonstrate ischemic wall motion abnormalities. They can be complemented by hybrid imaging with CTA to distinguish epicardial coronary artery disease and MB. This article will review different imaging modalities for the evaluation of the physiologic significance of MB.

Effects of Vessel Tortuosity on Coronary Hemodynamics: An Idealized and Patient-Specific Computational Study

Although coronary tortuosity can influence the hemodynamics of coronary arteries, the relationship between tortuosity and flow has not been thoroughly investigated partly due to the absence of a widely accepted definition of tortuosity and the lack of patient-specific studies that analyze complete coronary trees. Using a computational approach we investigated the effects of tortuosity on coronary flow parameters including pressure drop, wall shear stress, and helical flow strength as measured by helicity intensity. Our analysis considered idealized and patient-specific geometries. Overall results indicate that perfusion pressure decreases with increased tortuosity, but the patient-specific results show that more tortuous vessels have higher physiological wall shear stress values. Differences between the idealized and patient-specific results reveal that an accurate representation of coronary tortuosity must account for all relevant geometric aspects, including curvature imposed by the heart shape. The patient-specific results exhibit a strong correlation between tortuosity and helicity intensity, and the corresponding helical flow contributes directly to the observed increase in wall shear stress. Therefore, helicity intensity may prove helpful in developing a universal parameter to describe tortuosity and assess its impact on patient health. Our data suggest that increased tortuosity could have a deleterious impact via a reduction in coronary perfusion pressure, but the attendant increase in wall shear stress could afford protection against atherosclerosis.

Invasive evaluation of patients with angina in the absence of obstructive coronary artery disease

BACKGROUND

More than 20% of patients presenting to the cardiac catheterization laboratory with angina have no angiographic evidence of coronary artery disease. Despite a "normal" angiogram, these patients often have persistent symptoms, recurrent hospitalizations, a poor functional status, and adverse cardiovascular outcomes, without a clear diagnosis.

METHODS AND RESULTS

In 139 patients with angina in the absence of obstructive coronary artery disease (no diameter stenosis >50%), endothelial function was assessed; the index of microcirculatory resistance, coronary flow reserve, and fractional flow reserve were measured; and intravascular ultrasound was performed. There were no complications. The average age was 54.0±11.4 years, and 107 (77%) were women. All patients had at least some evidence of atherosclerosis based on an intravascular ultrasound examination of the left anterior descending artery. Endothelial dysfunction (a decrease in luminal diameter of >20% after intracoronary acetylcholine) was present in 61 patients (44%). Microvascular impairment (an index of microcirculatory resistance ≥25) was present in 29 patients (21%). Seven patients (5%) had a fractional flow reserve ≤0.80. A myocardial bridge was present in 70 patients (58%). Overall, only 32 patients (23%) had no coronary explanation for their angina, with normal endothelial function, normal coronary physiological assessment, and no myocardial bridging.

CONCLUSIONS

The majority of patients with angina in the absence of obstructive coronary artery disease have occult coronary abnormalities. A comprehensive invasive assessment of these patients at the time of coronary angiography can be performed safely and provides important diagnostic information that may affect treatment and outcomes.

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.

Impact of coronary tortuosity on the coronary blood flow: a 3D computational study

Tortuous coronary arteries are commonly observed but the etiology and clinical importance are still unclear. Hemodynamic factors are vital modulators of the vascular structure and a full understanding of hemodynamic changes caused by the coronary tortuosity (CT) is meaningful for clinical researches. A three-dimensional computational fluid dynamic study was conducted to evaluate hemodynamic changes caused by the CT. Six idealized small sections of the left anterior descending coronary artery (LAD) with different levels of tortuosity were employed. The dynamic vessel motion was added to the three-dimensional tortuous coronary models to make the computational results more realistic. The rest and exercise conditions were modeled by specifying proper boundary conditions. Results showed that a low and oscillated wall shear stress (WSS) region was formed at the inner wall downstream of the bend section when the bend angle was larger than 120°. The resistance of the coronary arteries increased up to 92% due to the CT during exercise. A maximum increase of 96% was observed in the mean diastole driving pressure for the CT model as compared to the non-tortuous model during exercise. This study indicated that the severe CT may be a risk factor for atherosclerosis and may make the regulation of the blood flow ineffective during exercise.

Impact of coronary tortuosity on coronary blood supply: a patient-specific study

BACKGROUND

Tortuous coronary arteries are commonly observed in clinical screenings and it may cause a reduction of the coronary pressure. However, whether this reduction leads to significant decreasing in the coronary blood supply is still unknown. The purpose of this study was to investigate the effect of the coronary tortuosity (CT) on the coronary blood supply.

METHOD

A computational fluid dynamics (CFD) study was conducted to evaluate the impact of tortuosity on the coronary blood supply. Two patient-specific left anterior descending coronary artery (LAD) models and the corresponding non-tortuous models were reconstructed to perform three-dimensional CFD analysis. The lumped parameter model was coupled to the outlet of the simulated branches to represent the absent downstream vasculatures. The rest and exercise conditions were modeled by specifying proper boundary conditions.

RESULT

Under resting condition, the mean flow rate could be maintained by decreasing less than 8% of the downstream vascular bed's resistance for tortuous models. While during exercise (maximal dilatation condition), the maximal coronary blood supply would reduce up to 14.9% due to tortuosity. Assuming that the flow rate can be maintained by the auto-regulation effect under the maximal dilatation condition, the distal resistances for CT models still have to reduce more than 23% to maintain blood perfusion.

CONCLUSIONS

Coronary tortuosity has minor influence on coronary blood supply at rest; while during exercise, patients with CT may lack the ability to adjust distal resistance sufficiently to compensate for the extra resistances generated by tortuosity and this may further lead to an ineffective regulation of the blood supply.