Sudden cardiac death from structural heart diseases in adults: imaging findings with cardiovascular computed tomography and magnetic resonance

Sudden cardiac death (SCD) is defined as the unexpected natural death from a cardiac cause within an hour of the onset of symptoms in the absence of any other cause. Although such a rapid course of death is mainly attributed to a cardiac arrhythmia, identification of structural heart disease by cardiovascular computed tomography (CCT) and cardiovascular magnetic resonance (CMR) imaging is important to predict the long-term risk of SCD. In adults, SCD most commonly results from coronary artery diseases, coronary artery anomalies, inherited cardiomyopathies, valvular heart diseases, myocarditis, and aortic dissection with coronary artery involvement or acute aortic regurgitation. This review describes the CCT and CMR findings of structural heart diseases related to SCD, which are essential for radiologists to diagnose or predict.     

Cardiac CT for acute chest pain in the emergency department: advantages of prospective triggering

Coronary CT angiography (CCTA) is emerging as a powerful tool for the diagnosis and characterization of coronary artery disease. In the emergency department (ED) setting, the high negative predictive value of CCTA has been shown to reduce the length of stay and the cost of care in the evaluation of patients at low and intermediate risk for an acute coronary syndrome (ACS). In addition, CCTA and triple-rule-out protocol CT examinations which simultaneously evaluate the coronary arteries, aorta and pulmonary arteries, have the potential to diagnose not only significant atherosclerotic coronary artery disease (CAD) and coronary artery anomalies, but noncoronary etiologies of chest pain, including pulmonary embolism, aortic dissection, infection, pleural and pericardial disease. Caution has been raised about the widespread use of CCTA in this setting, particularly given the prevalence of repeat ED visits for chest pain, due to the radiation exposure associated with retrospectively-gated CCTA. However, the recent development of prospectively-triggered coronary artery CTA makes the ED evaluation possible with a substantially lower radiation exposure to the patient. Although most studies of CCTA to date are performed with retrospective ECG gating, early reports on prospectively triggered CCTA demonstrate equivalent image quality and accuracy when compared to studies acquired with retrospective ECG gating.     

Cardiac CT for acute chest pain in the emergency department: advantages of prospective triggering

Coronary CT angiography (CCTA) is emerging as a powerful tool for the diagnosis and characterization of coronary artery disease. In the emergency department (ED) setting, the high negative predictive value of CCTA has been shown to reduce the length of stay and the cost of care in the evaluation of patients at low and intermediate risk for an acute coronary syndrome (ACS). In addition, CCTA and triple-rule-out protocol CT examinations which simultaneously evaluate the coronary arteries, aorta and pulmonary arteries, have the potential to diagnose not only significant atherosclerotic coronary artery disease (CAD) and coronary artery anomalies, but noncoronary etiologies of chest pain, including pulmonary embolism, aortic dissection, infection, pleural and pericardial disease. Caution has been raised about the widespread use of CCTA in this setting, particularly given the prevalence of repeat ED visits for chest pain, due to the radiation exposure associated with retrospectively-gated CCTA. However, the recent development of prospectively-triggered coronary artery CTA makes the ED evaluation possible with a substantially lower radiation exposure to the patient. Although most studies of CCTA to date are performed with retrospective ECG gating, early reports on prospectively triggered CCTA demonstrate equivalent image quality and accuracy when compared to studies acquired with retrospective ECG gating.     

Cardiac Computed Tomography

Computed tomography (CT) has emerged in the past decade as an important tool in the evaluation of cardiac pathology, specifically in the diagnosis of coronary artery disease (CAD). This article will review the technique and role of CT and CT angiography (CTA) in modern cardiovascular care. CT techniques are described, as are the applications of CT in the assessment of CAD including both calcium scoring and CTA. Although CAD is the mainstay of cardiac CT, important noncoronary cardiac applications including the evaluation of cardiac function, masses, valvular disease, and pericardial disease, are reviewed as well. The nursing care of the patient undergoing CTA is reviewed as are future developments within this field.     

Responsible Use of Computed Tomography in the Evaluation of Coronary Artery Disease and Chest Pain

Many options are available to clinicians for the noninvasive evaluation of the cardiovascular system and patient concerns about chest discomfort. Cardiac computed tomography (CT) is a rapidly advancing field of noninvasive imaging. Computed tomography incorporates coronary artery calcium scoring, coronary angiography, ventricular functional analysis, and information about noncardiac thoracic anatomy. We searched the PubMed database and Google from inception to September 2009 for resources on the accuracy, risk, and predictive capacity of coronary artery calcium scoring and CT coronary angiography and have reviewed them herein. Cardiac CT provides diagnostic information comparable to echocardiography, nuclear myocardial perfusion imaging, positron emission tomography, and magnetic resonance imaging. A cardiac CT study can be completed in minutes. In patients with a nondiagnostic stress test result, cardiac CT can preclude the need for invasive angiography. Prognostic information portends excellent outcomes in patients with normal study results. Use of cardiac CT can reduce health care costs and length of emergency department stays for patients with chest pain. Cardiac CT examination provides clinically relevant information at a radiation dose similar to well-established technologies, such as nuclear myocardial perfusion imaging. Advances in technique can reduce radiation dose by 90%. With appropriate patient selection, cardiac CT can accurately diagnose heart disease, markedly decrease health care costs, and reliably predict clinical outcomes.CAC = coronary artery calcium; CAD = coronary artery disease; CT = computed tomography; CTA = coronary computed tomographic angiography; EBCT = electron beam CT; ED = emergency department; ICA = invasive coronary angiography; MDCT = multidetector helical CT; MI = myocardial infarction; MPI = myocardial perfusion imaging; NPV = negative predictive value; PPV = positive predictive valueCardiac computed tomography (CT) is a rapidly evolving technology for the noninvasive evaluation of the cardiovascular system. Numerous potential roles for cardiac CT have been developed recently, such as investigating anomalous coronary arteries, evaluating for pulmonary vein stenoses, and preparing for repeated coronary artery bypass grafting. However, the indication of most interest to the public and physicians is evaluating patients for native vessel coronary artery disease (CAD) using coronary artery calcium (CAC) scoring and coronary computed tomographic angiography (CTA).We searched the PubMed database and Google, from inception to September 2009, for keywords coronary artery calcium, coronary CT angiography, and radiation risk to identify information sources of interest. We also searched references in other review articles. From Google, we selected publications from trusted sources, such as the Food and Drug Administration and the National Academy of Sciences. From PubMed, we selected articles about test performance characteristics based on the quality of their methods, preferentially using randomized controlled trial data. We selected articles about clinical outcomes from randomized trials when available and from large cohorts as secondary sources. The purpose of this review is to summarize the recent data regarding accuracy, sensitivity, and specificity of CTA and the responsible use of cardiac CT.     

Cardiac CT in the Diagnosis and Postoperative Assessment of Congenital Heart Disease

Patients with complex congenital heart disease require serial diagnostic evaluation throughout their lives. Although echocardiography and cardiac MRI are the primary modes of evaluation in the current era, cardiac computed tomography (CT) plays an increasingly important role for specific indications. The high temporal and spatial resolution of the most modern CT scanners used for cardiac imaging allows for rapid, high quality image acquisition. The decreased need for sedation and anesthesia combined with recent developments markedly reducing radiation exposure make it an ideal imaging modality for certain indications in congenital heart disease. This article will briefly review the current use of noninvasive diagnostics in congenital heart disease, focusing on the use of CT for the most common congenital heart lesions referred for surgical intervention. When used appropriately, CT angiography (CTA) can provide critical information necessary to care for patients with congenital heart disease who require evaluation in addition to echocardiography.     

German cardiac CT registry: indications,procedural data and clinical consequences in 7061 patients undergoing cardiac computed tomography

Cardiac computed tomography permits quantification of coronary calcification as well as detection of coronary artery stenoses after contrast enhancement. Moreover, cardiac CT offers high-resolution morphologic and functional imaging of cardiac structures which is valuable for various structural heart disease interventions and electrophysiology procedures. So far, only limited data exist regarding the spectrum of indications, image acquisition parameters as well as results and clinical consequences of cardiac CT examinations using state-of-the-art CT systems in experienced centers. Twelve cardiology centers with profound expertise in cardiovascular imaging participated in the German Cardiac CT Registry. Criteria for participation included adequate experience in cardiac CT as well of the availability of a 64-slice or newer CT system. Between 2009 and 2014, 7061 patients were prospectively enrolled. For all cardiac CT examinations, patient parameters, procedural data, indication and clinical consequences of the examination were documented. Mean patient age was 61?±?12 years, 63% were males. The majority (63%) of all cardiac CT examinations were performed in an outpatient setting, 37% were performed during an inpatient stay. 91% were elective and 9% were scheduled in an acute setting. In most examinations (48%), reporting was performed by cardiologists, in 4% by radiologists and in 47% of the cases as a consensus reading. Cardiac CT was limited to native acquisitions for assessment of coronary artery calcification in 9% of patients, only contrast-enhanced coronary CT angiography was performed in 16.6% and combined native and contrast-enhanced coronary CT angiography was performed in 57.7% of patients. Non-coronary cardiac CT examinations constituted 16.6% of all cases. Coronary artery calcification assessment was performed using prospectively ECG-triggered acquisition in 76.9% of all cases. The median dose length product (DLP) was 42 mGy cm (estimated effective radiation dose of 0.6 mSv). Coronary CT angiography was performed using prospectively ECG-triggered acquisition in 77.3% of all cases. Tube voltage was 120 kV in 67.8% of patients and 100 kV in 30.7% of patients, with a resultant median DLP of 256 mGy cm (estimated effective dose of 3.6 mSv). Clinical consequences of cardiac CT were as follows: in 46.8% of the cases, invasive coronary angiography could be avoided; ischemia testing was recommended in 4.7% of the cases, invasive coronary angiography was recommended in 16.4% of the cases and change in medication in 21.6% of the examinations. Cardiac CT is performed in the majority of patients for non-invasive evaluation of the coronary arteries. CT frequently resulted in medication change, and otherwise planned downstream testing including invasive angiography could be avoided in a high percentage of patients. Radiation exposure in experienced centers is relatively low.     

Integrative computed tomographic imaging of coronary artery disease

Rapid technological evolution in multislice computed tomography (CT) over the last decade with improved spatial and temporal resolution has enabled cardiac CT to become a viable and effective alternative in the diagnosis of coronary artery disease. Within recent years CT coronary angiography has demonstrated high sensitivity and specificity, and in particular a very high negative-predictive value, making it a valuable imaging modality for ruling out suspected coronary artery disease. In addition, CT angiography demonstrates accuracy in the detection and characterization of coronary plaques, and it has been reported to play an important role in predicting disease progression and cardiac events. The goal of this article is to provide an overview on the role and current clinical applications of cardiac CT in the evaluation of coronary artery disease. Emerging areas of cardiac CT, including dual-energy CT and CT myocardial perfusion are also discussed, as well as the limitations and future directions of cardiac CT.     

Ultrafast CT and the cardiovascular system

Ultrafast computed tomography (CT) is a new imaging technique that relies on electron beam technology. Its rapid image acquisition speeds make it ideal for evaluating the cardiovascular system. The high-resolution, flow, and cine-modes are unique and provide complimentary information about cardiovascular anatomy, function, and flow dynamics. Ultrafast CT can provide quantitative measurements of cardiac output, ejection fraction, ventricular volumes, and ventricular mass as well as evaluation of segmental cardiac function. This technique can be used to assess coronary artery bypass graft patency as well as to screen for coronary artery calcium. Intracardiac thrombus or tumor, valvular disease, and disorders of the pericardium can be evaluated and characterized using ultrafast CT. The diagnosis of congenital lesions of the heart and great vessels is facilitated by this imaging modality, which can help determine complex anatomic abnormalities and quantitate shunt lesions. Acquired lesions of the great vessels, such as aortic dissection and aneurysm, can be diagnosed by ultrafast CT, which can also be used for serial examination and conservative management.     

交叉肺动脉患儿临床及CT特点(附17例报道)

目的 探讨交叉肺动脉患儿的临床及CT特点。方法 回顾性分析17例交叉肺动脉患儿的临床及CT检查资料,记录合并心血管畸形、气道畸形、肺炎及其他临床合并症情况。结果 心胸CT三维重建图像可清晰显示交叉肺动脉及其合并心血管畸形、气道畸形、肺炎。其中合并房间隔缺损9例,室间隔缺损9例,主动脉右弓右降9例,动脉导管未闭5例,迷走左或右锁骨下动脉4例,主动脉缩窄3例,法洛四联症3例,主肺动脉间隔缺损2例,部分型肺静脉异位引流2例,左肺动脉狭窄1例,主动脉瓣狭窄1例,主动脉瓣二叶畸形1例,永存动脉干1例,右心室双出口1例,主动脉离断1例,肺动脉闭锁1例,冠状动脉起源异常1例,主动脉左弓右降1例,永存左上腔静脉1例,心肌致密化不全1例。10例合并肺炎,其中2例有支气管狭窄。其他临床合并症包括18-三体综合征、顽固性低钙血症、癫痫各1例。结论 交叉肺动脉是一种罕见的先天性心脏病,常伴其他心脏、大血管发育异常,且多合并肺炎。CT三维重建图像可直观、清晰显示交叉肺动脉及其合并心血管解剖异常,同时显示肺内、气道异常及其与大血管的立体关系。     

Noninvasive screening for coronary atherosclerosis and silent ischemia in asymptomatic high-risk populations

Asymptomatic subjects at risk for adverse cardiovascular events, based on clinical risk models, are further risk-stratified by noninvasive imaging of coronary atherosclerosis and silent ischemia. Coronary atherosclerosis can be detected by imaging coronary artery calcification (CAC). CAC scores more than 400 are associated with a higher cardiac event rate. Silent ischemia can be detected by stress perfusion imaging employing single photon emission CT or positron emission tomography. Asymptomatic type 2 diabetics and those with advanced kidney disease represent high-risk populations. Asymptomatic diabetics with high CAC scores have a higher prevalence and extent of silent ischemia than those with low scores. The greater the extent of CAC, the worse the outcome. For asymptomatic chronic kidney disease patients, the larger the extent of stress perfusion abnormalities, the higher the cardiac mortality rate. New molecular imaging approaches for assessing myocardial metabolism and detecting vulnerable coronary plaques hold promise for risk stratification.     

Cardiac Micro-PET-CT

Molecular imaging is a rapidly emerging field, with the use of multi-modality or hybrid technology scanners for in vivo investigations covering a broad spectrum of disease. Cardiac micro-PET-CT is one such promising multimodality. Standalone imaging technologies such as PET and CT have existed for several decades, however, they have only recently been utilized in concert, mainly for clinical cancer imaging. Cardiovascular events are responsible for nearly one-third of deaths in North America every year. Atherosclerosis, coronary artery disease (CAD), and heart failure are the most common types of heart disease. Cardiac imaging-related research into their prevention and treatment has contributed to a decrease in mortality. This review outlines the recent progress in the development and application of advanced cardiac micro-PET-CT technology. Current development of novel PET radiotracers focusing on diagnosis and characterization of different stages of atherosclerosis is discussed, as well as myocardial perfusion radiotracers mimicking previously established SPECT tracers and others. Small animal (mouse and rat) models of disease investigated with cardiac imaging are becoming more common, and will facilitate rapid translation to clinical studies with improvement in micro-PET-CT technology. Also, increasingly popular animal models for cardiovascular disease research such as mini-pigs and rabbits are used with interventional therapies, including catheterization due to larger artery sizes. The emergence of cardiac CT will be discussed with comparison between preclinical and clinical approaches, including consideration of radiation doses.     

Pharmacologic Stress Agents for Cardiac Imaging

Non-invasive cardiac imaging plays a major role in modern Cardiology and is becoming an essential step in the assessment of patients with known or suspected coronary artery disease. In this setting, cardiac imaging is combined with stress to assess the functional significance of coronary stenosis. Dynamic exercise is the most physiological form of stress and hence it is regarded as the stress modality of choice. When exercise is not possible, pharmacological stress can be used as an effective and safe alternative. We here describe the mechanism of action, protocols, indications and contraindications as well as the diagnostic performance and safety profile of all pharmacological agents currently available for stress imaging with an emphasis on the newly developed A_2A adenosine receptor agonist, regadenoson.     

Noninvasive cardiac imaging

Noninvasive cardiac imaging can be used for the diagnostic and prognostic assessment of patients with suspected or known coronary artery disease. It is central to the treatment of patients with myocardial infarction, coronary artery disease, or acute coronary syndromes with or without angina. Radionuclide cardiac imaging; echocardiography; and, increasingly, cardiac computed tomography and cardiac magnetic resonance imaging techniques play an important role in the diagnosis of coronary artery disease, which is the leading cause of mortality in adults in the United States. Contemporary imaging techniques, with either stress nuclear myocardial perfusion imaging or stress echocardiography, provide a high sensitivity and specificity in the detection and risk assessment of coronary artery disease, and have incremental value over exercise electrocardiography and clinical variables. They also are recommended for patients at intermediate to high pretest likelihood of coronary artery disease based on symptoms and risk factors. Cardiac magnetic resonance imaging and cardiac computed tomography are newly emerging modalities in the evaluation of patients with coronary artery disease. Cardiac magnetic resonance imaging is useful in the assessment of myocardial perfusion and viability, as well as function. It also is considered a first-line tool for the diagnosis of arrhythmogenic right ventricular dysplasia. Cardiac computed tomography detects and quantifies coronary calcium and evaluates the lumen and wall of the coronary artery. It is a clinical tool for the detection of subclinical coronary artery disease in select asymptomatic patients with an intermediate Framingham 10-year risk estimate of 10 to 20 percent. In addition, cardiac computed tomography is evolving as a noninvasive tool for the detection and quantification of coronary artery stenosis. Although guidelines can help with treating patients, treatment ultimately should be tailored to each person based on clinical judgment of the a priori risk of a cardiac event, symptoms, and the cardiac risk profile.     

The prominent role of cardiac magnetic resonance imaging in coronary artery disease

The role of cardiac magnetic resonance (CMR) in coronary artery disease is prominent. CMR provides functional and structural heart disease assessment with high accuracy. It allows accurate cardiac volume and flow quantification and wall motion analysis both at rest and at stress. CMR myocardial perfusion studies detect myocardial ischemia and provide insights into the morphology of the myocardial tissue. CMR imaging noninvasively differentiates causes of myocardial injury such as ischemia or inflammation; stages of myocardial injury, such as acute or chronic; grade of myocardial damage, such as reversible or irreversible; myocardial fibrosis or scar. There is an emerging role of CMR in patients with acute chest presentation since it can demonstrate causes of chest pain other than coronary artery disease such as myocarditis, pericarditis, aortic dissection and pulmonary embolism. CMR is noninvasive and radiation-free. It’s combined approach of functional and structural cardiac assessment makes it unique compared with other imaging modalities.     

Prevalence and Significance of Obstructive Coronary Artery Disease in Patients with Zero Coronary Artery Calcium Score

Abundant data have established coronary artery calcium score (CACS) in the algorithm of cardiovascular risk stratification, especially for those at intermediate risk of coronary artery disease (CAD). Absence of CACS is associated with a very low cardiac event rate in asymptomatic individuals and no further imaging is required. Cardiac event rates in symptomatic patients are comparatively higher but still relatively low and have to be interpreted in the context of the population included. Conflicting results from angiography literature with a reported presence of obstructive CAD in up to 39% of mostly symptomatic patients with zero CACS are explained by the higher-risk patients enrolled. CACS is an excellent test for asymptomatic patients in predicting cardiac events and absence of obstructive CAD but has a limited role in symptomatic and higher-risk patients encountered by a cardiovascular specialist, particularly those referred for CT angiography and invasive coronary angiography. This is especially true for relatively young patients (<45 years of age).     

Coronary Artery CT Angiography for Plaque Imaging

Cardiac CT is becoming a mainstream and integral part of many cardiology practices based on a vast base of literature supporting and validating its clinical utility. As the technology continues to advance, coronary imaging has improved in stride. In the next several years, cardiac CT may become the “gatekeeper” of cardiac testing, surpassing the more common and widespread nuclear testing as the initial strategy in evaluating ischemia. Unfortunately, in spite of an arsenal of tests available to detect clinically significant stable coronary artery disease, many people continue to suffer acute myocardial infarction and other acute coronary syndromes, leading to significant morbidity and mortality due to unstable coronary artery disease. These unstable, “vulnerable” plaques continue to plague cardiologists across the globe. The ability to identify vulnerable plaque is a step in the right direction toward therapy. It is in this particular arena that advancements in cardiac CT technology may bear the most fruit. A growing body of evidence supporting the utility of cardiac CT in plaque imaging has emerged and has demonstrated that potentially unstable coronary artery disease is able to be identified accurately and noninvasively.     

Diagnosis of acute coronary syndrome

The term "acute coronary syndrome" encompasses a range of thrombotic coronary artery diseases, including unstable angina and both ST-segment elevation and non-ST-segment elevation myocardial infarction. Diagnosis requires an electrocardiogram and a careful review for signs and symptoms of cardiac ischemia. In acute coronary syndrome, common electrocardiographic abnormalities include T-wave tenting or inversion, ST-segment elevation or depression (including J-point elevation in multiple leads), and pathologic Q waves. Risk stratification allows appropriate referral of patients to a chest pain center or emergency department, where cardiac enzyme levels can be assessed. Most high-risk patients should be hospitalized. Intermediate-risk patients should undergo a structured evaluation, often in a chest pain unit. Many low-risk patients can be discharged with appropriate follow-up. Troponin T or I generally is the most sensitive determinant of acute coronary syndrome, although the MB isoenzyme of creatine kinase also is used. Early markers of acute ischemia include myoglobin and creatine kinase-MB subforms (or isoforms), when available. In the future, advanced diagnostic modalities, such as myocardial perfusion imaging, may have a role in reducing unnecessary hospitalizations.     

血浆血小板激活因子酰基脱水酶与心血管疾病

血小板激活因子 (PAF)为强有力的炎症介导剂 ,PAF酰基脱水酶 (PAF AH )能水解PAF使其失活 ,在一些心血管疾病中起重要作用 ,如在缺血与再灌注 (I/R)中起保护作用 ,也与冠心病、动脉粥样硬化、腹主动脉瘤、非家族性扩张型心肌病以及心外科围术期密切相关     

Calcification of the heart: mechanisms and therapeutic avenues

Introduction: Coronary artery calcification (CAC) is reflective of atherosclerotic disease and incrementally predictive of future cardiovascular events (CVE), independent of traditional risk factors. Extra coronary calcium such as aortic valve calcification, which can be identified and quantified by computed tomography (CT) imaging, has shown to predict future CVE in both asymptomatic and symptomatic (i.e. stable angina and acute coronary syndrome [ACS]) settings. It has hence been a vital tool in studies involving new therapies for cardiovascular disease.

Areas covered: In this review, promising therapies on the horizon are reviewed, along with the role of cardiac CT and coronary calcification in these studies. A Medline search for peer-reviewed publications using keywords related to coronary calcium score, aortic valve calcium, and therapies targeting the same was carried out.

Expert commentary: CT scanning provides a distinct means of detecting and quantifying coronary plaque as well as valvular calcification with excellent reproducibility. Based on voluminous data available, the absence of coronary calcium serves as a factor to de-risk patients for cardiovascular risk stratification and management algorithms. Newer therapies have shown to lower progression of coronary calcification, thus being beneficial in slowing progression of atherosclerotic disease. As British Epidemiologist Geoffrey Rose states, the best predictor of a life-threatening disease is the early manifestation of that disease. As CAC represents the early manifestation of atherosclerosis, it is the best-known stratifier of risk today, and its clinical use will continue to rise.