Coronary Artery Segments Research Articles

Left main coronary artery disease: pathophysiology, diagnosis, and treatment.

The advent of coronary angiography in the 1960s allowed for the risk stratification of patients with stable angina. Patients with unprotected left main coronary artery disease have an increased risk of death related to the large amount of myocardium supplied by this vessel. Although coronary angiography remains the preferred imaging modality for the evaluation of left main coronary artery stenosis, this technique has important limitations. Angiograms of the left main coronary artery segment can be difficult to interpret, and almost one-third of patients can be misclassified when fractional flow reserve is used as the reference. In patients with clinically significant unprotected left main coronary artery disease, surgical revascularization was shown to improve survival compared with medical therapy and has been regarded as the treatment of choice for unprotected left main coronary artery disease. Two large-scale clinical trials published in 2016 support the usefulness of catheter-based revascularization in selected patients with unprotected left main coronary artery disease. In this Review, we describe the pathophysiology of unprotected left main coronary artery disease, discuss diagnostic approaches in light of new noninvasive and invasive imaging techniques, and detail risk stratification models to aid the Heart Team in the decision-making process for determining the best revascularization strategy for these patients.

Radiation Dose Reduction at Low Tube Voltage CCTA Based on the CNR Index

We compared the radiation dose and diagnostic accuracy on 120- and 100-kVp coronary computed tomography angiography (CCTA) scans whose contrast-to-noise ratio (CNR) was the same. We studied 1311 coronary artery segments from 100 patients. For 120-kVp scans, the targeted image level was set at 25 Hounsfield units (HU). For 100-kVp scans, the targeted noise level was set at 30 HU to obtain the same CNR as at 120 kVp. We compared the CNR and the radiation dose on scans acquired at 120 and 100 kVp. Invasive coronary angiography (ICA) images were evaluated by an interventional coronary angiography specialist, and CCTA images were evaluated by a radiologist. Coronary artery disease was defined as a luminal narrowing ≧50% for ICA and CCTA. With ICA considered the gold standard, the diagnostic accuracy (sensitivity, specificity, positive predictive value, and negative predictive value) was analyzed on both 120- and 100-kVp CCTA images. We also compared the diagnostic accuracy for area under the receiver operating characteristic curve of the ICA and CCTA performed at 120 and 100 kVp. Two blinded observers visually evaluated the septal branch. The mean dose-length product was 48% lower at 100 kVp than at 120 kVp (P < .01). Under the 120-kVp CCTA protocol, the area under the curve, 95% confidence interval, sensitivity, specificity, positive predictive value, and negative predictive value were 0.94%, 0.91%-0.96%, 94.0%, 93.0%, 82.3%, and 98.1%, respectively; at 100 kVp these values were 0.94%, 0.92%-0.97%, 96.1%, 92.0%, 85.2%, and 98.0%, respectively. Area under the receiver operating characteristic curve analysis revealed no significant difference in diagnostic accuracy between the two protocols (P = .87). At the same CNR, the 100-kVp CCTA protocol may help to reduce the radiation dose by approximately 50% compared to the 120-kVp protocol without degradation of diagnostic accuracy.

Art care: A multi-modality coronary 3D reconstruction and hemodynamic status assessment software.

Due to the incremental increase of clinical interest in the development of software that allows the 3-dimensional (3D) reconstruction and the functional assessment of the coronary vasculature, several software packages have been developed and are available today. Taking this into consideration, we have developed an innovative suite of software modules that perform 3D reconstruction of coronary arterial segments using different coronary imaging modalities such as IntraVascular UltraSound (IVUS) and invasive coronary angiography images (ICA), Optical Coherence Tomography (OCT) and ICA images, or plain ICA images and can safely and accurately assess the hemodynamic status of the artery of interest. The user can perform automated or manual segmentation of the IVUS or OCT images, visualize in 3D the reconstructed vessel and export it to formats, which are compatible with other Computer Aided Design (CAD) software systems. We employ finite elements to provide the capability to assess the hemodynamic functionality of the reconstructed vessels by calculating the virtual functional assessment index (vFAI), an index that corresponds and has been shown to correlate well to the actual fractional flow reserve (FFR) value. All the modules of the proposed system have been thoroughly validated. In brief, the 3D-QCA module, compared to a successful commercial software of the same genre, presented very good correlation using several validation metrics, with a Pearson's correlation coefficient (R) for the calculated volumes, vFAI, length and minimum lumen diameter of 0.99, 0.99, 0.99 and 0.88, respectively. Moreover, the automatic lumen detection modules for IVUS and OCT presented very high accuracy compared to the annotations by medical experts with the Pearson's correlation coefficient reaching the values of 0.94 and 0.99, respectively. In this study, we have presented a user-friendly software for the 3D reconstruction of coronary arterial segments and the accurate hemodynamic assessment of the severity of existing stenosis.

Comparative Study between Multislice Computed Tomography Coronary Angiography and Invasive Coronary Angiography in Diagnosis of Mid and Distal Segment Coronary Artery Stenosis

AbstractBackground: Computed Tomography Coronary Angiog-raphy (CCTA) is a promising method for detection and exclu-sion of obstructive coronary artery stenosis. Mid and distal segments of coronary arteries were chosen because they are usually small in caliber especially distal segment (usually less than 1.5mm) and they are affected by cardiac motion on the contrary, the proximal segment is always away from the myocardium and usually larger in diameter so that it can be easily diagnosed by CCTA.Objective: The purpose of this study was to evaluate the added value of CT coronary angiography for detecting Coro-nary Artery Disease (CAD) in mid and distal segment lesions using invasive coronary angiography as a reference standard.Methods: We prospectively evaluated 20 patients who suspected to have CAD and underwent CTA. we assessed mid and distal segment lesions using invasive coronary angiography as a reference standard. We excluded proximal segment lesion, high calcium score (800), arrhythmias, post percutaneous coronary intervention and post coronary artery bypass graft.Results: A total of 20 subjects underwent both CCTA and ICA (60% were females with mean age: 58.1 years). On a patient based model, the sensitivity, specificity, and positive and negative predictive values to detect mid segment lesions were 88.9%, 95.2%, 88.9%, and 95.2% respectively and for distal lesions were 85%, 100%, 100%, 98.1%, respectively. Diagnosis of mid and distal segment lesions by both CT and coronary angiography showed statistically significant strong positive correlation.Conclusion: CT angiography is a reliable tool and has high accuracy for detection of CAD in both mid and distal segment lesions. Importantly, the high NPV (97%) firmly establishes CCTA as an effective noninvasive method to rule out obstructive coronary artery stenosis in patient with mod-erate pre-test probability.

A Preliminary Study of Computed Tomography Coronary Angiography Within a Single Cardiac Cycle in Patients With Atrial Fibrillation Using 256-Row Detector Computed Tomography.

The purpose of this study was to evaluate the image quality and radiation dose of computed tomography (CT) coronary angiography using a 256-row detector CT scanner in a single cardiac cycle in patients with atrial fibrillation (AF). Seventy consecutive patients (41 men and 29 women; age range was from 37 to 84 years, mean age was 61.7 ± 10.2 years; body mass index range was from 15.08 to 36.45 kg/m, mean body mass index was 25.9 ± 3.5 kg/m) with persistent or paroxysmal AF during acquisition, who were not receiving any medications for heart rate (HR) regulation, were imaged with a 256-row detector CT scanner (Revolution CT, GE healthcare). According to the HR or HR variability (HRV) the patients were divided into 4 groups: group A (HR, ≥75 bpm; n = 36), group B (HR, <75 bpm; n = 34), group C (HRV, ≥50 bpm; n = 26), and group D (HRV, <50 bpm; n = 44). The snapshot freeze algorithm reconstruction was used to reduce motion artifacts whenever necessary. Two experienced radiologists, who were blinded to the electrocardiograph and reconstruction information, independently graded the CT images in terms of visibility and artifacts with a 4-grade rating scale (1, excellent; 2, good; 3, poor; 4, insufficient) using the 18-segment model. Subjective image quality scores and effective dose (ED) were calculated and compared between these groups. The HR during acquisition ranged from 47 to 222 bpm (88.24 ± 36.80 bpm). A total of 917 in 936 coronary artery segments were rated as diagnostically evaluable (98.2 ± 0.04%). There was no significant linear correlation between mean image quality and HR or HRV (P > 0.05). Snapshot freeze reconstruction technique was applied in 28 patients to reduce motion artifacts and thus showed image quality was improved from 93.2% to 98.4%. The ED was 3.05 ± 2.23 mSv (0.49-11.86 mSv) for all patients, and 3.76 ± 2.22 mSv (0.92-11.17 mSv), 2.30 ± 2.02 mSv (0.49-11.86 mSv), 3.89 ± 2.35 mSv (1.18-11.86 mSv), and 2.56 ± 2.03 mSv (0.49-11.17 mSv) for groups A, B, C, and D, respectively. There were significant differences in mean ED between groups A and B, as well as C and D (P <0.05). This study shows that CT coronary angiography with use of a new 256-row detector CT in single cardiac cycle achieves diagnostic image quality but with lower radiation dose in patients with AF. Heart rate or HRV has no significant effect on image quality.

Vasomotor function in rat arteries after ex vivo and intragastric exposure to food-grade titanium dioxide and vegetable carbon particles

BackgroundHumans are continuously exposed to particles in the gastrointestinal tract. Exposure may occur directly through ingestion of particles via food or indirectly by removal of inhaled material from the airways by the mucociliary clearance system. We examined the effects of food-grade particle exposure on vasomotor function and systemic oxidative stress in an ex vivo study and intragastrically exposed rats.MethodsIn an ex vivo study, aorta rings from naïve Sprague-Dawley rats were exposed for 30 min to food-grade TiO2 (E171), benchmark TiO2 (Aeroxide P25), food-grade vegetable carbon (E153) or benchmark carbon black (Printex 90). Subsequently, the vasomotor function was assessed in wire myographs. In an in vivo study, lean Zucker rats were exposed intragastrically once a week for 10 weeks to vehicle, E171 or E153. Doses were comparable to human daily intake. Vasomotor function in the coronary arteries and aorta was assessed using wire myographs. Tetrahydrobiopterin, ascorbate, malondialdehyde and asymmetric dimethylarginine were measured in blood as markers of oxidative stress and vascular function.ResultsDirect exposure of E171 to aorta rings ex vivo increased the acetylcholine-induced vasorelaxation and 5-hydroxytryptamine-induced vasocontraction. E153 only increased acetylcholine-induced vasorelaxation, and Printex 90 increased the 5-hydroxytryptamine-induced vasocontraction, whereas Aeroxide P25 did not affect the vasomotor function. In vivo exposure showed similar results as ex vivo exposure; increased acetylcholine-induced vasorelaxation in coronary artery segments of E153 and E171 exposed rats, whereas E171 exposure altered 5-hydroxytryptamine-induced vasocontraction in distal coronary artery segments. Plasma levels of markers of oxidative stress and vascular function showed no differences between groups.ConclusionGastrointestinal tract exposure to E171 and E153 was associated with modest albeit statistically significant alterations in the vasocontraction and vasorelaxation responses. Direct particle exposure to aorta rings elicited a similar type of response. The vasomotor responses were not related to biomarkers of systemic oxidative stress.

Research Progress and Forensic Application on the Pathogenesis of Coronary Artery Spasm

Coronary artery spasm （CAS） is a hyper-contraction of segmental coronary artery in response to multiple stimuli. At present, it's still in lack of specific diagnostic indicators of sudden cardiac death caused by CAS. This review summarizes current researches on the mechanisms of CAS and describes the roles of vascular endothelial dysfunction and vascular smooth muscle hypersensitivity in the course of CAS. Furthermore, the molecular mechanisms of the endogenous NO and endothelin-1 cause vascular endothelial dysfunction, and the phosphorylation of MLC2, Rho kinase and endoplasmic reticulum stress related to vascular smooth muscle hypersensitivity are discussed. Meanwhile, the possibility of forensic application for the related molecules on the diagnosis of sudden cardiac death caused by CAS are also explored.

Insulin resistance in an animal model of polycystic ovary disease is aggravated by vitamin D deficiency: Vascular consequences

Hyperandrogenic state in females is accompanied with metabolic syndrome, insulin resistance and vascular pathologies. A total of 67%-85% of hyperandrogenic women suffer also from vitamin D deficiency. We aimed to check a potential interplay between hyperandrogenism and vitamin D deficiency in producing insulin resistance and effects on coronary resistance arteries. Adolescent female rats were divided into four groups, 11-12 animals in each. Transdermal testosterone-treated and vehicle-treated animals were kept either on vitamin D-deficient or on vitamin D-supplemented diet for 8 weeks. Plasma sexual steroid, insulin, leptin and vitamin D plasma levels were measured, and oral glucose tolerance test was performed. In coronary arterioles, insulin receptor and vitamin D receptor expressions were tested by immunohistochemistry, and insulin-induced relaxation was measured in vitro on isolated coronary resistance artery segments. Testosterone impaired glucose tolerance, and it diminished insulin relaxation but did not affect the expression of insulin and vitamin D receptors in vascular tissue. Vitamin D deficiency elevated postprandial insulin levels and homeostatic model assessment insulin resistance. It also diminished insulin-induced coronary arteriole relaxation, while it raised the expression of vitamin D and insulin receptors in the endothelial and medial layers. Our conclusion is that both hyperandrogenism and vitamin D deficiency reduce sensitivity of coronary vascular tissue to insulin, but they do it with different mechanisms.

Prevalence and clinical characteristics of patients with myocardial bridging in a population from North Kerala

BackgroundMyocardial bridging refers to a condition in which a band of myocardial tissue overlies a segment of an epicardial coronary artery. The exact prevalence of this entity is not known and varies considerably in different studies. In this study, we aimed to estimate the prevalence of myocardial bridging from consecutive coronary angiograms done over a period of last seven years at our institute and also assess the clinical and angiographic profile of these patients. Method and resultsA total of 3146 coronary angiograms were reviewed and 153 patients were found to be having myocardial bridging. The prevalence of myocardial bridging was 4.86%, which was highest among the previously reported Indian studies. 89 (58.16%) patients had isolated myocardial bridging without significant coronary artery involvement where as the rest 64 (41.83%) had coronary artery disease (CAD). The incidence of diabetes mellitus and family history of CAD was significantly higher in patients with myocardial bridges and CAD compared to those with myocardial bridges without significant CAD. 49 patients with hypertrophic cardiomyopathy underwent coronary angiogram out of which myocardial bridging was seen in 8 (16.32%) patients. Among patients with rheumatic heart disease (RHD), the incidence of myocardial bridging was 3.44%. ConclusionThe study showed a higher incidence of myocardial bridging then that of previous Indian studies. A significant proportion of patients presented with angina and acute coronary syndrome despite having no coronary artery disease. The incidence was higher in patients with hypertrophic cardiomyopathy whereas it was similar to that of general population in patients with rheumatic heart disease.

Measurements of Lumen Areas and Diameters of Proximal and Middle Coronary Artery Segments in Subjects Without Coronary Atherosclerosis

There are plenty of data on morphology and lumen dimensions of diseased coronary arteries. However, information on normal coronary vessel anatomy is scarce. We provided computed tomography angiography-derived reference values of lumen dimensions in proximal and middle coronary segments in a healthy population with respect to gender and vessel dominance. Consecutive 2,849 computed tomography angiography examinations were reviewed to identify 201 subjects (77 men, patient age 50 ± 13 years) whose coronary arteries were free from any sign of atherosclerosis (calcium score 0, no detectable plaque). For all proximal and middle coronary segments, lumen areas (LAs) and lumen diameters were measured. Coronary vessel segmentation and dominance pattern were defined using the Syntax Score. Normal values of LAs and lumen diameters were significantly smaller for women compared with men except for the proximal right coronary artery and the left main coronary artery (LMCA) (20.2 ± 6.6 mm2 vs 23.0 ± 6.1 mm2, p = 0.0003, and 5.0 ± 0.8 mm vs 5.4 ± 0.7 mm, p = 0.0001). The lower limit of normal for the LMCA (defined as mean LA - 2 standard deviations) equaled 7.0 and 10.8 mm2 for women and men, respectively. Subjects with left (vs right) coronary dominance had significantly larger areas and diameters of the LMCA (26.2 ± 9.2 mm2 vs 20.7 ± 6.0 mm2, p = 0.0017, and 5.7 ± 1.0 mm vs 5.1 ± 0.7 mm, p = 0.0017, respectively) and proximal left circumflex (13.8 ± 2.7 mm2 vs 10.4 ± 3.8 mm2, p = 0.0001, and 4.2 ± 0.4 mm vs 3.6 ± 0.7 mm, p = 0.0001, respectively) and smaller areas and diameters of the proximal right coronary artery (7.1 ± 2.0 mm2 vs 13.3 ± 3.6 mm2, p <0.0001, and 3.0 ± 0.4 mm vs 4.1 ± 0.6 mm, p <0.0001, respectively). In conclusion, gender and coronary artery dominance pattern significantly impact normal LAs and dimensions in subjects without coronary atherosclerosis.

An Outflow Boundary Condition Model for Noninvasive Prediction of Fractional Flow Reserve in Diseased Coronary Arteries.

This paper reports on a new boundary condition formulation to model the total coronary myocardial flow and resistance characteristics of the myocardial vascular bed for any specific patient when considered for noninvasive diagnosis of ischemia. The developed boundary condition model gives an implicit representation of the downstream truncated coronary bed. Further, it is based on incorporating patient-specific physiological parameters that can be noninvasively extracted to account for blood flow demand to the myocardium at rest and hyperemic conditions. The model is coupled to a steady three-dimensional (3D) collocated pressure-based finite volume flow solver and used to characterize the "functional significance" of a patient diseased coronary artery segment without the need for predicting the hemodynamics of the entire arterial system. Predictions generated with this boundary condition provide a deep understanding of the inherent challenges behind noninvasive image-based diagnostic techniques when applied to human diseased coronary arteries. The overall numerical method and formulated boundary condition model are validated via two computational-based procedures and benchmarked with available measured data. The newly developed boundary condition is used via a designed computational methodology to (a) confirm the need for incorporating patient-specific physiological parameters when modeling the downstream coronary resistance, (b) explain the discrepancies presented in the literature between measured and computed fractional flow reserve (FFRCT), and

Extremely tortuous coronary arteries - when optical coherence tomography and fractional flow reserve did not help us much

Introduction. Extreme coronary tortuosity may lead to flow alteration resulting in a reduction in coronary pressure distal to the tortuous segment, subsequently leading to ischemia. Therefore the detection of a true cause of ischemia, i.e. whether a fixed stenosis or tortuosity by itself is responsible for its creation, with non-invasive and invasive methods is a real challenge. Case report. We presented a case of a patient with a history of stable angina [Canadian Cardiovascular Society (CCS class II)], an abnormal stress test and coronary tortuosity without hemodynamically significant stenosis. Due to suspected linear lesion between the two bends in proximal segment of Right coronary artery (RCA) we performed optical coherence tomography (OCT), minimum lumen area (MLA)-13.19 mm2) and fractional flow reserve (FFR) RCA (0.94). We opted for conservative treatment for stable angina. Conclusion. When tortuosities are associated with atherosclerosis in coronary artery for determination of true cause of ischemia invasive methods can be used, such as OCT and FFR. &lt;br&gt;&lt;br&gt;&lt;font color="red"&gt;&lt;b&gt; This article has been corrected. Link to the correction &lt;u&gt;&lt;a href="http://dx.doi.org/10.2298/VSP1912304E"&gt;10.2298/VSP1912304E&lt;/a&gt;&lt;u&gt;&lt;/b&gt;&lt;/font&gt;

Coronary artery-positive remodeling in current smokers.

This study aims to evaluate the association of the coronary artery-positive remodeling (CAPR) observed on cardiac computed tomography angiography (CCTA) with cigarette smoking. This retrospective case-control study enrolled 178 consecutive patients with CAPR plaque (case group) and 180 consecutive patients with coronary artery plaque, but no positive remodeling (control group). CAPR was evaluated in CCTA images and defined as at least 10% larger vessel diameter at the plaque site compared with a normal reference segment. The average age of this population was 61.8±11.5 years (30.4% women). In the case group, the prevalences of current smokers, former smokers, and nonsmokers were 15.7, 26.4, and 57.9%, respectively. In the control group, the prevalences were 6.1, 20.6, and 73.3%, respectively, which were significantly different from the control group (P=0.002 for all). In a subanalysis of the CAPR location in the CAPR group, CAPR was more prevalent in the proximal than the distal segments of the major coronary arteries. Most of the patients in the case group had only one segment involvement with CAPR (71.35%). Logistic regression analyses showed that a history of current smoking has a significant correlation with CAPR in both unadjusted and adjusted models after controlling for risk factors. Current smokers have a 3.5-fold higher risk of having CAPR compared with nonsmokers (P<0.01). There is a significant independent association between a history of cigarette smoking and CAPR evaluated by CCTA. Current cigarette smokers have a 3.5 times higher risk of having CAPR.

Intravascular Ultrasound-Guided Management of Proximal Left Anterior Descending Artery Aneurysm With Covered Stent - A Case Report

Coronary artery aneurysm is defined as the localized dilatation of a coronary artery segment more than 1.5 times the size of adjacent normal segments. The aneurysms of the coronary arteries are rare. Coronary aneurysms can be congenital or acquired. The majority are atherosclerotic in origin. The primary complication is myocardial ischemia or infarction, sudden cardiac death with rupture being rare. Some aneurysms are diagnosed incidentally in arteries other than the culprit artery. Treatment options include medical management with anticoagulation, percutaneous intervention with covered stents or surgery. We report a case of 67-year-old male who presented with acute coronary syndrome. Coronary angiogram showed a moderate size aneurysm of the proximal left anterior descending artery. This aneurysm was successfully managed percutaneously with a covered stent.

Impact of SSF on Diagnostic Performance of Coronary Computed Tomography Angiography Within 1 Heart Beat in Patients With High Heart Rate Using a 256-Row Detector Computed Tomography.

The aim of this study was to investigate the impact of a motion-correction algorithm on diagnostic accuracy of coronary computed tomography angiography (CCTA) within 1 heart beat in patients with high heart rate (HR) using a 256-row detector CT. Sixty-four consecutive patients with known or suspected coronary artery disease (symptomatic) and with HR of 75 beats per minute or greater (mean [SD] HR, 82.6 [7.3] beats per minute) undergoing CCTA and invasive coronary angiography within 4 weeks were prospectively enrolled. Coronary computed tomography angiography was performed with a 256-row detector CT (Revolution CT, GE Healthcare) using prospectively electrocardiography-triggered volume scan in 1 heart beat. All images were reconstructed using standard (STD) algorithm and a motion-correction algorithm reconstruction (Snapshot Freeze SSF; GE Healthcare) technique. The image quality of coronary artery segments was evaluated by 2 experienced radiologists using a 4-point scale based on the 18-segment model. Diagnostic accuracy was compared between STD and SSF for significant lumen stenosis (≥50%) of each segment with invasive coronary angiography as the reference standard for determining significant stenosis. The diagnostic sensitivity, specificity, positive predictive value, and negative predictive value with STD and SSF were 93.7%, 85.1%, 50.2%, and 98.8% versus 91.9%, 95.8%, 77.9%, and 98.7% on per-segment assessment; 98.7%, 74.0%, 62.9%, and 99.2% versus 96.2%, 94.4%, 77.9%, and 98.7% on per-artery assessment; and 100%, 14.3%, 70.5%, and 100% versus 100%, 85.7%, 93.5%, and 100% on per-patient assessment, respectively. There was a significant difference in accuracy between STD and SFF on per-patient level 71.9% versus 95.3%, on per-artery level 81.6% versus 94.9%, and per-segment level 86.3% versus 95.3%, respectively. The area under receiver operating characteristics curve analysis also showed a significant improvement on diagnostic performance with the SSF technique versus with the STD algorithm on per-patient level (P < 0.001), with corresponding area under the curve being 0.91 (95% confidence interval, 0.79-1.00) and 0.60 (95% confidence interval, 0.44-0.75). The mean effective dose was 2.0 mSv. Coronary computed tomography angiography can be performed in patients with high HR within 1 heart beat yielding low radiation dose. The use of SSF technique reconstruction for 1 heart beat CCTA achieves significant improvements in image quality and diagnostic value.

Automatic Coronary Centerline Extraction Using Gradient Vector Flow Field and Fast Marching Method From CT Images

In current medical imaging, coronary artery stenosis quantification requires fast and accurate coronary centerline computation. This paper develops a new framework for extracting coronary centerlines from 3-D segmented coronary arteries models. The approach utilizes the gradient vector flow (GVF) filed-based speed image of the vessel model and implements a wavefront propagation technique for centerline branch tracking. The approach was validated over 17 3-D synthetic vessel models. The results showed a good agreement between the proposed method and ground truth centerline in synthetic vessel models with an average distance of 0.25 mm and overlap measure of 96.0%, given the CT scans with a resolution of about $0.3\,\,\mathrm {mm}\times 0.3\mathrm {mm}\times 0.4\mathrm {mm}$ . Second, the proposed method was further tested in six clinical coronary arteries models reconstructed from computed tomography coronary angiography in human patients and found to be applicable in both left coronary arteries and right coronary arteries with an average processing time of 16 minutes per case. In conclusion, the proposed GVF field and the fast marching-based method should have more routine clinical applicability.

Coronary computed tomography in heart transplant patients: detection of significant stenosis and cardiac allograft vasculopathy, image quality, and radiation dose.

Background Cardiac allograft vasculopathy (CAV) is an accelerated form of atherosclerosis unique to heart transplant (HTX) patients. Purpose To investigate the detection of significant coronary artery stenosis and CAV, determinants of image quality, and the radiation dose in coronary computed tomography angiography (CCTA) of HTX patients with 64-slice multidetector CT (64-MDCT). Material and Methods Fifty-two HTX recipients scheduled for invasive coronary angiography (ICA) were prospectively enrolled and underwent CCTA before ICA with intravascular ultrasound (IVUS). Results Interpretable CCTA images were acquired in 570 (95%) coronary artery segments ≥2 mm in diameter. Sensitivity, specificity, and positive and negative predictive values of CCTA for the detection of segments with significant stenosis (lumen reduction ≥50%) on ICA were 100%, 98%, 7.7%, and 100%, respectively. Twelve significant stenoses were located in segments with uninterpretable image quality or vessel diameter <2 mm; only one was eligible for intervention. IVUS detected CAV (maximal intimal thickness ≥0.5 mm) in 33/41 (81%) patients; CCTA and ICA identified CAV (any wall or luminal irregularity) in 18 (44%) and 14 (34%) of these 33 patients, respectively. The mean estimated radiation dose was 19.0 ± 3.4 mSv for CCTA and 5.7 ± 3.3 mSv for ICA ( P < 0.001). Conclusion CCTA with interpretable image quality had a high negative predictive value for ruling out significant stenoses suitable for intervention. The modest detection of CAV by CCTA implied a limited value in identifying subtle CAV. The high estimated radiation dose for 64-MDCT is of concern considering the need for repetitive examinations in the HTX population.

Sağ Koroner Arter Anjiyografisi Sırasında Opak Basıncına Bağlı Distalde Kese Görüntüsüne Neden Olan Subadventisiyal Diseksiyon Olgusu

Iatrogenic dissections during coronary interventions can be observed in daily practice. However, dissections due to opaque injection are much less common. Herein, we present a case of subaventitial dissection developed in the distal segment of right coronary artery after opaque injection. Dissection was not catheter-related and was conservatively treated as there was no leak out of the coronary artery.

UDP-sugars activate P2Y14 receptors to mediate vasoconstriction of the porcine coronary artery

AimsUDP-sugars can act as extracellular signalling molecules, but relatively little is known about their cardiovascular actions. The P2Y14 receptor is a Gi/o-coupled receptor which is activated by UDP-glucose and related sugar nucleotides. In this study we sought to investigate whether P2Y14 receptors are functionally expressed in the porcine coronary artery using a selective P2Y14 receptor agonist, MRS2690, and a novel selective P2Y14 receptor antagonist, PPTN (4,7-disubstituted naphthoic acid derivative). Methods and resultsIsometric tension recordings were used to evaluate the effects of UDP-sugars in porcine isolated coronary artery segments. The effects of the P2 receptor antagonists suramin and PPADS, the P2Y14 receptor antagonist PPTN, and the P2Y6 receptor antagonist MRS2578, were investigated. Measurement of vasodilator-stimulated phosphoprotein (VASP) phosphorylation using flow cytometry was used to assess changes in cAMP levels. UDP-glucose, UDP-glucuronic acid UDP-N-acetylglucosamine (P2Y14 receptor agonists), elicited concentration-dependent contractions of the porcine coronary artery. MRS2690 was a more potent vasoconstrictor than the UDP-sugars. Concentration dependent contractile responses to MRS2690 and UDP-sugars were enhanced in the presence of forskolin (activator of cAMP), where the level of basal tone was maintained by addition of U46619, a thromboxane A2 mimetic. Contractile responses to MRS2690 were blocked by PPTN, but not by MRS2578. Contractile responses to UDP-glucose were also attenuated by PPTN and suramin, but not by MRS2578. Forskolin-induced VASP-phosphorylation was reduced in porcine coronary arteries exposed to UDP-glucose and MRS2690, consistent with P2Y14 receptor coupling to Gi/o proteins and inhibition of adenylyl cyclase activity. ConclusionsOur data support a role of UDP-sugars as extracellular signalling molecules and show for the first time that they mediate contraction of porcine coronary arteries via P2Y14 receptors.

Influence of irregular heart rhythm on radiation exposure, image quality and diagnostic impact of cardiac computed tomography angiography in 4,339 patients. Data from the German Cardiac Computed Tomography Registry

BackgroundCoronary computed tomography angiography (coronary CTA) provides non-invasive evaluation of the coronary arteries with high precision for the detection of significant coronary artery disease (CAD). AimTo investigate whether irregular heart rhythm including atrial fibrillation and premature beats during data acquisition influences (i) radiation and contrast media exposure, (ii) number of non-evaluable coronary segments and (iii) diagnostic impact of coronary CTA. MethodsTwelve tertiary care centers with ≥64 slice CT scanners and ≥5 years of experience with cardiovascular imaging participated in this registry. Between 2009 and 2014, 4339 examinations were analysed in patients who underwent clinically indicated coronary CTA for suspected CAD. Clinical and epidemiologic data were gathered from all patients. In addition, clinical presentation, heart rate and rhythm during the scan, Agatston score, radiation and contrast media exposure and the diagnostic impact of coronary CTA were systematically analysed. ResultsOf 4339 patients in total, 260 (6.0%) had irregular heart rhythm, whereas the remaining 4079 (94.0%) had stable sinus rhythm. Patients with irregular heart rhythm were older (63.2 ± 12.5yrs versus 58.6 ± 11.4yrs. p < 0.001), exhibited a higher rate of pathologic stress tests before CTA (37.1% versus 26.1%, p < 0.01) and higher heart rates during CTA compared to those with sinus rhythm (62.5 ± 11.6bpm versus 58.9 ± 8.5bpm, p < 0.001). Both contrast media exposure and radiation exposure were significantly higher in patients with irregular heart rhythm (90 mL (95%CI = 80–110 mL) versus 80 mL (95%CI = 70–90 mL) and 6.2 mSv (95%CI = 2.5–11.7) versus 3.3 mSv (95%CI = 1.7–6.9), p < 0.001 for both). Coronary CTA excluded significant CAD less frequently in patients with irregular heart rhythm (32.9% versus 44.8%, p < 0.001). This was attributed to the higher rate of examinations with at least one non-diagnostic coronary segment in patients with irregular heart rhythm (10.8% versus 4.6%, p < 0.001). Subsequent invasive angiography could be avoided in 47.2% of patients with irregular heart rhythm compared to 52.9% of patients with sinus rhythm (p = NS), whereas downstream stress testing was recommended in 3.2% of patients with irregular heart rhythm versus 4.0% of patients with sinus rhythm (p = NS). ConclusionA significant number of patients scheduled for coronary CTA have irregular heart rhythm in a real-world clinical setting. In such patients, heart rate during coronary CTA is higher, possibly resulting in (i) higher radiation and contrast agent exposure and (ii) more frequent coronary CTA examinations with at least one non-diagnostic coronary artery segment. However, this does not seem to lead to increased downstream stress testing or subsequent invasive procedures.