Cardiac Imaging Techniques Research Articles

Imaging cardiac activation sequence during ventricular tachycardia in a canine model of nonischemic heart failure

Noninvasive cardiac activation imaging of ventricular tachycardia (VT) is important in the clinical diagnosis and treatment of arrhythmias in heart failure (HF) patients. This study investigated the ability of the three-dimensional cardiac electrical imaging (3DCEI) technique for characterizing the activation patterns of spontaneously occurring and norepinephrine (NE)-induced VTs in a newly developed arrhythmogenic canine model of nonischemic HF. HF was induced by aortic insufficiency followed by aortic constriction in three canines. Up to 128 body-surface ECGs were measured simultaneously with bipolar recordings from up to 232 intramural sites in a closed-chest condition. Data analysis was performed on the spontaneously occurring VTs (n=4) and the NE-induced nonsustained VTs (n=8) in HF canines. Both spontaneously occurring and NE-induced nonsustained VTs initiated by a focal mechanism primarily from the subendocardium, but occasionally from the subepicardium of left ventricle. Most focal initiation sites were located at apex, right ventricular outflow tract, and left lateral wall. The NE-induced VTs were longer, more rapid, and had more focal sites than the spontaneously occurring VTs. Good correlation was obtained between imaged activation sequence and direct measurements (averaged correlation coefficient of ∼0.70 over 135 VT beats). The reconstructed initiation sites were ∼10 mm from measured initiation sites, suggesting good localization in such a large animal model with cardiac size similar to a human. Both spontaneously occurring and NE-induced nonsustained VTs had focal initiation in this canine model of nonischemic HF. 3DCEI is feasible to image the activation sequence and help define arrhythmia mechanism of nonischemic HF-associated VTs.

CAVITY SEGMENTATION AND STROKE VOLUME MEASUREMENT METHODS FROM ECHOCARDIOGRAPHIC IMAGES: REVIEW

The complexity and criticality of heart disease dia gnosis and treatment have frequently attracted the attention of researchers to develop approaches that can handle accurate clinical assessments. One of t hese complexities is measuring the Right Ventricle strok e volume. Therefore, different cardiac imaging techniques have been developed to help specialists in their regular clinical work and in the operating theatre to assist in the diagnosis, monitoring of the treat ment and to ensure the success of a cardiac interve ntion as far as possible. Echocardiography is one of the car diac imaging techniques and is considered as the mo st effective imaging technique as it is minimally inva sive, quick and the cheapest method. Many studies h ave been conducted on Right Ventricle assessment from echocariographic images. This review is aimed at presenting the previous technical elements and algo rithms used to measure the ventricle stroke volume from echocardiographic images. The review focuses on the five technical approaches that have been used, whi ch are pre-processing, End-Distally (ED) and End-Systo lic (ES) frame detection, cavity segmentation, the stoke volume measurement and 3D reconstruction. Finally, a summary will conclude this study.

T1 and T2 mapping: new perspectives in cardiac magnetic resonance imaging

Cardiac magnetic resonance (MR) imaging is currently considered the gold standard for characterizing changes in myocardial structure, in particular to assess myocardial edema and focal fibrosis. In spite of this potential capability, the traditional MR sequences usually employed for these purposes have significant limitations and provide only qualitative information. Recent developments in cardiac MR imaging techniques currently provide clinically-feasible mapping of T1 and T2 relaxation times, thus providing a quantitative assessment of the parameters of interest. Myocardial edema can be evaluated using T2 mapping techniques. These have shown a superior performance compared to the traditional T2-weighted and STIR sequences, both in acute inflammatory cardiomyopathies and in acute ischemic injury. T1 mapping techniques, performed both with and without contrast medium, enable to quantify diffuse myocardial fibrosis and to assess myocardial edema and infiltration. This article will review current methodologies for cardiac T1 and T2 parametric mapping and their potential and limitations in the assessment of myocardial damage.

Screening in asymptomatic coronary artery disease: helpful, redundant or harmful?

Screening asymptomatic individuals remains the subject of intense debate in medicine. In the beginning of 2014 the use of screening for breast cancer in women was seriously questioned based on studies from Canada (Toronto) and the Netherlands (Leiden). It was shown that, particularly in women over 70 years, screening for breast cancer might even bring more harm than benefit in terms of over diagnosis and thus overtreatment. With respect to carotid artery disease, in September of this year the United States Preventive Services Task Force (USPSTF) published a recommendation to oppose the screening of the general adult population to detect asymptomatic carotid artery stenosis [1]. The Task Force found that ultrasound may produce false-positives resulting in angiography or even surgery, with the accompanying high risk of stroke, heart attack, or death. This recommendation may be important because it may influence insurance coverage. How about screening individuals with asymptomatic coronary artery disease? In a review article from the Netherlands (Rotterdam) a systematic review of guidelines on imaging of asymptomatic coronary artery disease showed the light in 2011 [2]. It turned out that guideline on risk assessment by imaging of asymptomatic coronary artery disease contained conflicting recommendations. Out of the 14 guidelines that met the inclusion criteria, eight guidelines recommended against or found insufficient evidence for testing individuals with asymptomatic coronary artery disease. The authors suggested therefore that more research, including randomized controlled trials, is needed to evaluate the impact of imaging on clinical outcomes and costs. Over the past years cardiac computed tomography (CT) has emerged as a screening tool - in addition to the proven use of major risk factors - to detect coronary artery disease in an early stage of its process [3–7]. Both calcium scoring and coronary CT angiography have been shown useful to identify coronary artery lesions. However, how does one manage the issue of using coronary CT as a screening test in asymptomatic individuals? According to the 2013 ESC Guidelines on Stable Angina Pectoris [8], both coronary calcium detection by CT and coronary CT angiography receive a Class III indication, meaning that there is ‘evidence and/or general agreement that the procedure is not useful/effective and in some cases may be harmful’. The inherent guideline recommendations were twofold: 1) coronary calcium detection by CT is not recommended to identify individuals with coronary artery disease, and 2) coronary CT angiography is not recommended as a screening test in asymptomatic individuals without clinical suspicion of coronary artery disease. Apart from the lack of usefulness of applying CT in asymptomatic individuals one should always be aware of the risk of radiation exposure using ionising imaging modalities to detect patients with coronary artery disease. To that purpose, the American Heart Association (AHA) very recently issued a scientific statement on cardiac imaging, published online on 29 September 2014 in the journal Circulation [9]. The AHA scientific statement recommended that exposure to radiation should be part of the discussion on cardiac imaging for both referring and performing physicians. Physicians should be required to know which cardiac imaging tests use ionising radiation, understand the basics of exposure, and know the typical dose estimates for the most commonly used cardiac imaging procedures. In addition, they should counsel patients on the risks as well as on potential benefits so that patients can give truly informed consent. Consequently, before referring a patient for a cardiac imaging test, the AHA recommends that physicians address important questions such as 1) how will the test help diagnose or treat the cardiac problem, 2) are there alternative modalities not using radiation, 3) what are the levels of radiation exposure, 4) how will it affect the risk of cancer later in life, and 5) how does that compare with the risk from other common activities. These questions remain pertinent despite successful technological attempts to reduce radiation exposure, which holds in particular for cardiac CT. To conclude, although screening for coronary artery disease -especially using advanced ionising cardiac imaging techniques [10] - may be helpful in patients with a intermediate to high probability of disease, it may be redundant in patients with a low prevalence of disease and even harmful in asymptomatic individuals.

Effects of bariatric surgery on right ventricular structure and function.

Left ventricular (LV) changes associated with obesity, including LV hypertrophy and impaired LV function, have been shown to be reverted by bariatric surgery. Little is known about the effects of bariatric procedures on right ventricle (RV). We analyzed the literature in order to provide a comprehensive information on RV structural and functional changes, as assessed by imaging techniques, after bariatric surgery. The studies were identified by the following search terms: 'bariatric surgery', 'obesity', 'left ventricle', 'right ventricle', 'left ventricular hypertrophy', 'right ventricular hypertrophy', 'cardiac hypertrophy', 'ventricular dysfunction', 'echocardiography', 'magnetic resonance imaging' and 'cardiac imaging techniques'.In a pooled population of 537 obese patients with preserved systolic function enrolled in eight studies, bariatric surgery induced beneficial effects on RV morphology and function; the procedures reverted obesity-related right ventricular hypertrophy as suggested by a significant decrease in RV mass, and improved systolic and diastolic RV performance as assessed by traditional and newer echocardiographic indexes. Decrements in body mass index and improvement in obstructive sleep apnea were major factors independently related to the improved RV structure and function. The present review shows that bariatric surgery exerts beneficial effects on RV structure and function in morbidly obese patients. As RV changes are independent predictors of outcomes, improvement of RV structure and function may contribute to the cardioprotective effects of bariatric surgery.

Evolution of Cardiac Imaging According to the Number of Scientific Articles in Medical Journals: a Long and Fruitful Journey

The use of cardiac imaging techniques as a diagnostic method in the understanding of physiopathology, as well as in cardiology research has been one of the most important revolutions in the management of cardiac patients, our understanding of physiopathology, and basic research in almost all heart diseases. This article analyzes the literature on echocardiography, cardiovascular magnetic resonance imaging, computed tomography, and nuclear medicine during the last 60 years and provides an overview of how these techniques have developed and how their introduction into daily practice has changed attitudes among cardiologists. The literature not only shows that the implementation of these techniques in daily practice requires an immense amount of research and effort by many working groups throughout the scientific world, but also that techniques that once seemed promising may finally be discarded.

Evolución de la imagen cardiaca a través de las publicaciones científicas en revistas médicas: un largo y fecundo camino

The use of cardiac imaging techniques as a diagnostic method in the understanding of physiopathology, as well as in cardiology research has been one of the most important revolutions in the management of cardiac patients, our understanding of physiopathology, and basic research in almost all heart diseases. This article analyzes the literature on echocardiography, cardiovascular magnetic resonance imaging, computed tomography, and nuclear medicine during the last 60 years and provides an overview of how these techniques have developed and how their introduction into daily practice has changed attitudes among cardiologists. The literature not only shows that the implementation of these techniques in daily practice requires an immense amount of research and effort by many working groups throughout the scientific world, but also that techniques that once seemed promising may finally be discarded.Full English text available from:www.revespcardiol.org/en

094 * OFF-PUMP TRANSAPICAL MITRAL VALVE REPAIR WITH NEOCHORDAE

Objectives: On-pump mitral valve repair is well established and currently the gold standard. Off-pump mitral valve repair has so far not been feasible. Based on improved online cardiac imaging techniques such as 3D echocardiography, a closed application technique of neochordae in prolapsed leaflet segments with a newly developed device, Neochord DS 1000, has been developed. We present our experience with this technique in 8 patients with mitral valve prolapse. Methods: Eight patients, age 60 ± 12.8 years, 5 male, presented with severe mitral regurgitation with mitral valve (MV) prolapse of the posterior mitral leaflet, left ventricular ejection fraction 51.6 ± 7.4%, pulmonary arterial pressure 52.5 ± 20.3 (40–100) mmHg, atrial fibrillation in 2 patients, left atrial diameter 47.1 ± 3.3 mm, left ventricular end diastolic diameter 61.9 ± 8.3 mm, AP diameter (MV) 41.9 ± 1.45 mm. Surgery was performed via left mini-thoracotomy (5th intercostal space, medioclavicular line). The chordal implantation tool was inserted 2D/3D guided under heparin (activated clotting time >300 s) through the ventricular apex laterally on beating heart. Under sophisticated 2D/3D echo-guidance, the artificial chordae (GoreTex 4-0) were placed with the Neochord DS 1000 System; the number of neochordae was 3 in 6 patients and 4 in 2 patients. Adjustment was done under continuous 2D/3D echo-control. Results: There were no operative complications and no blood transfusions. Residual MI was zero in 5, trace in 2 and I–II in 1 patient. All patients were extubated within 3 h. Echo at discharge as well as at follow-up (4.1 ± 1.9 months) was stable except for one patient with increase of MI due to ventricular remodelling. Conclusion: Off-pump minimal invasive mitral valve repair with artificial chordae is feasible with excellent short-term results. Long-term observation is neccessary to confirm durability.

Toward microendoscopy-inspired cardiac optogenetics in vivo: technical overview and perspective.

The ability to perform precise, spatially localized actuation and measurements of electrical activity in the heart is crucial in understanding cardiac electrophysiology and devising new therapeutic solutions for control of cardiac arrhythmias. Current cardiac imaging techniques (i.e. optical mapping) employ voltage- or calcium-sensitive fluorescent dyes to visualize the electrical signal propagation through cardiac syncytium in vitro or in situ with very high-spatiotemporal resolution. The extension of optogenetics into the cardiac field, where cardiac tissue is genetically altered to express light-sensitive ion channels allowing electrical activity to be elicited or suppressed in a precise cell-specific way, has opened the possibility for all-optical interrogation of cardiac electrophysiology. In vivo application of cardiac optogenetics faces multiple challenges and necessitates suitable optical systems employing fiber optics to actuate and sense electrical signals. In this technical perspective, we present a compendium of clinically relevant access routes to different parts of the cardiac electrical conduction system based on currently employed catheter imaging systems and determine the quantitative size constraints for endoscopic cardiac optogenetics. We discuss the relevant technical advancements in microendoscopy, cardiac imaging, and optogenetics and outline the strategies for combining them to create a portable, miniaturized fiber-based system for all-optical interrogation of cardiac electrophysiology in vivo.

Cardiac imaging in prosthetic paravalvular leaks.

Prosthetic paravalvular leaks (PVL) is an uncommon but serious complication after surgical valve replacement. Although surgery has been the traditional treatment of choice in hemodynamically significant PVL, percutaneous transcatheter closure is emerging as a novel and less invasive option for patients with high operative risk. Cardiac imaging, especially two- and three-dimensional transoesophageal echocardiography, plays an essential role in the diagnosis, guidance of intervention and subsequently in the evaluation of the outcomes of the procedure. The aim of this manuscript is to review the role of cardiac imaging techniques in the interventional management of patients with symptomatic PVL.

Beyond ultrasound: advances in multimodality cardiac imaging.

The rapid technological evolution accomplished in noninvasive cardiac imaging techniques over the past few decades has provided physicians with a large armamentarium for the evaluation of patients with known or suspected coronary heart disease. Noninvasive assessment of coronary artery calcium or noninvasive coronary angiography may be performed using computed tomography or magnetic resonance imaging. These techniques evaluate the presence of atherosclerosis rather than ischemia. Conversely, nuclear cardiology is the most widely used noninvasive approach for the assessment of myocardial perfusion and function. These techniques coupled with the development of dedicated image fusion software packages to merge data sets from different modalities have paved the way for hybrid imaging. This article provides a description of the available noninvasive imaging techniques in the assessment of coronary anatomy, myocardial perfusion, and cardiac function in patients with known or suspected coronary heart disease.

Pre-clinical functional Magnetic Resonance Imaging part II: The heart

One third of all deaths worldwide in 2008 were caused by cardiovascular diseases (CVD), and the incidence of CVD related deaths rises ever more. Thus, improved imaging techniques and modalities are needed for the evaluation of cardiac morphology and function.Cardiac magnetic resonance imaging (CMRI) is a minimally invasive technique that is increasingly important due to its high spatial and temporal resolution, its high soft tissue contrast and its ability of functional and quantitative imaging. It is widely accepted as the gold standard of cardiac functional analysis.In the short period of small animal MRI, remarkable progress has been achieved concerning new, fast imaging schemes as well as purpose-built equipment. Dedicated small animal scanners allow for tapping the full potential of recently developed animal models of cardiac disease. In this paper, we review state-of-the-art cardiac magnetic resonance imaging techniques and applications in small animals at ultra-high fields (UHF).

Role of three-dimensional echocardiography in management of acquired intracardiac shunts.

Gerbode defect and sinus of Valsalva aneurysm fistula are congenital and acquired forms of intracardiac shunt. The increasing prevalence of invasive, recurrent cardiovascular procedures cause tissue damage and has led to more iatrogenic and acquired cases of predominantly congenital shunt over time. We report 2 cases of acquired intracardiac fistula precisely defined by Real time three-dimensional transesophageal echocardiography (3DTEE). The first case is a 70-year-old male with Gerbode defect after second aortic valve replacement surgery due to prosthetic valve endocarditis and the other case is a 41-year-old male with sinus of Valsalva aneurysm fistula between aorta and right atrium post subclinical infective endocarditis. Advanced cardiac imaging techniques such as cardiac computerized tomography, MRI and Real time three-dimensional (3D) echocardiography help to precisely detect intracardiac fistula and provide detailed anatomic and physiologic information. The relatively low cost, lack of radiation exposure, portability and guiding characteristic make real time 3DTEE an imaging technique with arguably the most advantages. Surgical repair is the usual treatment for intracardiac shunt, and percutaneous catheter-based closure is a less invasive alternative.

Why is a new journal dedicated to echocardiography required?

Why is a new journal dedicated to echocardiography required?

The role of echocardiography in the evaluation of cardiac damage in hypertensive obese patient.

Obesity rates are rising worldwide. Often obesity is associated with hypertension leading to an increased cardiovascular risk. Both obesity and hypertension induce several modifications in cardiac structure and function, particularly atrial and ventricular remodeling is a common finding shared by these two conditions. It has been demonstrated obesity leads to: left ventricular (LV) mass increase, LV systolic and diastolic dysfunction, left atrium (LA) size increase, LA function alterations and pericardial fat accumulation. Nowadays, the development of cardiac imaging techniques allows to early identifying any preclinical damage related to hypertension and obesity. This could be very important in order to improve patient management and medical therapy.

Temporal changes in left ventricular mechanics: impact of bed rest and exercise (884.23)

BACKGROUND: The use of more sensitive and specific echocardiographic techniques, such as speckle‐tracking imaging, may address the current limitations of conventional cardiac imaging techniques to provide insight into the magnitude and time course of cardiac deconditioning following spaceflight or head‐down tilt bed rest (HDTBR). METHODS: Speckle‐tracking assessment of longitudinal, radial, and circumferential strain and twist was used to evaluate the impact of 70 days of HDTBR (n=7) and HDTBR + exercise (n=11) on temporal changes in left ventricular (LV) mechanics. Echocardiograms were performed before (BR‐2), during (BR31, 70), and following (BR+4h) HDTBR. Repeated measures ANOVA was used to evaluate the effect of HDTBR on cardiac variables in control and exercise subjects. RESULTS: After sedentary HDTBR, longitudinal (‐19.0 ± 1.8% vs. ‐14.9 ± 2.4%) and radial (15.0 ± 1.9% vs. 11.3 ± 2.2%) strain and twist (18.0 ± 4.0° vs. 17.0 ± 3.6°) were significantly impaired. In contrast, exercise preserved LV mechanics, and there were non‐significant improvements from BR‐2 to BR70 in longitudinal strain (‐18.7 ± 1.5% vs. ‐20.4 ± 2.7%), radial strain (13.2 ± 2.4% vs. 14.2 ± 1.6%), and twist (16.3 ± 3.6° vs. 18.6 ± 5.9°). CONCLUSIONS: Speckle‐tracking echocardiography provides important new insight into temporal changes in LV mechanics during disuse and exercise training.Grant Funding Source: NASA Johnson Space Center’s Human Research Program

PT388 Impact of introduction of CT coronary angiography into the Australian Medicare Benefits Schedule on use of other non-invasive cardiac diagnostic imaging techniques

PT388 Impact of introduction of CT coronary angiography into the Australian Medicare Benefits Schedule on use of other non-invasive cardiac diagnostic imaging techniques

Myocardial Clefts, Crypts, or Crevices

With the increasing accuracy of cardiac imaging techniques, new findings, not or rarely observed before, come to light. In particular, the improvement in high spatial resolution of a multiplanar imaging technique such as cardiac magnetic resonance (CMR), associated with its increased contrast between blood and endocardial border surface of current cine images, led the appreciation of subtle left ventricular (LV) wall structural features, not seen or neglected by 2-dimensional echocardiography. This is the case of myocardial clefts, described both in hypertrophic cardiomyopathy (HCM) and in healthy volunteers, thus providing another hot potato to the hands of the clinical cardiologist. Article see p 259 These myocardial invaginations have been variably called clefts, crypts, fissures, crevices, and atypical LV noncompaction. Although the etiopathogenesis remains a matter of debate, it is a common belief that they represent a failure to resorb the trabeculated part of ventricular wall during normal embryological development, as seen in isolated LV noncompaction.1,2 Before the development of coronary circulation, the myocardium consists of a spongy meshwork of interwoven myocardial fibers organized into trabeculae with deep recesses, the latter communicating with the LV cavity and enabling a direct blood supply to the myocardium. Myocardial crypts have been described within the LV wall of patients with HCM since early postmortem studies.3–5 In particular, to the best of our knowledge, the first pathological description of a myocardial cleft dates back to 1958, in the historical publication of Donald Teare.3 Noteworthy, Teare …

Sequence Comparison for Non-Enhanced MRA of the Lower Extremity Arteries at 7 Tesla

In this study three sequences for non-contrast-enhanced MRA of the lower extremity arteries at 7T were compared. Cardiac triggering was used with the aim to reduce signal variations in the arteries. Two fast single-shot 2D sequences, a modified Ultrafast Spoiled Gradient Echo (UGRE) sequence and a variant of the Quiescent-Interval Single-Shot (QISS) sequence were triggered via phonocardiogram and compared in volunteer examinations to a non-triggered 2D gradient echo (GRE) sequence. For image acquisition, a 16-channel transmit/receive coil and a manually positionable AngioSURF table were used. To tackle B1 inhomogeneities at 7T, Time-Interleaved Acquisition of Modes (TIAMO) was integrated in GRE and UGRE. To compare the three sequences quantitatively, a vessel-to-background ratio (VBR) was measured in all volunteers and stations. In conclusion, cardiac triggering was able to suppress flow artifacts satisfactorily. The modified UGRE showed only moderate image artifacts. Averaged over all volunteers and stations, GRE reached a VBR of 4.18±0.05, UGRE 5.20±0.06, and QISS 2.72±0.03. Using cardiac triggering and TIAMO imaging technique was essential to perform non-enhanced MRA of the lower extremities vessels at 7T. The modified UGRE performed best, as observed artifacts were only moderate and the highest average VBR was reached.

Significance of left ventricular clefts—A case report

We describe the case of a 48-year-old patient who presented with an out-of-hospital cardiac arrest due to an acute ST-elevation myocardial infarction. Left ventriculography performed during the initial coronary angiography revealed the presence of structural abnormalities in the myocardial wall which subsequently, with the use of contrast echocardiography and cardiac magnetic resonance imaging, were confirmed to represent ventricular clefts. We reviewed the pathophysiological significance of these defects and compared them with similarly looking abnormalities such as aneurysms, pseudoaneurysms, and diverticula. In conclusion, recognition of ventricular clefts is needed to allow clinicians to differentiate them from other myocardial wall defects with different pathological profile and clinical significance.<Learning objective: With emerging techniques in cardiac imaging some cardiac abnormalities such as left ventricular (LV) clefts are recognized more frequently. This case report describes an incidental finding of LV cleft and provides an extensive review of the literature regarding the clinical significance and differential from other similar findings of different pathology. That will help physicians to distinguish these overlapping findings and tailor patients’ management accordingly.>