Karthikeyan Ananthasubramaniam

Rubidium-82 cardiac positron emission tomography imaging: an overview for the general cardiologist.

Cardiac positron emission tomography (PET) imaging has been used for more than 3 decades to study myocardial perfusion and metabolism, but for a majority of those years, confined to large academic and research centers with access to a cyclotron. With the advent of the generator-produced PET radionuclide Rubidium-82, PET myocardial perfusion imaging has become far more accessible in daily practice, and is backed by a strong evidence-base for the diagnosis and prognosis of coronary artery disease and myocardial viability. Intended to describe basic principles for the general cardiologist, this review highlights the role of Rb-82 in PET myocardial perfusion imaging and provides an overview of its properties, its diagnostic accuracy for diagnosing coronary artery disease and myocardial viability, and some unique applications.

Regadenoson: review of its established role in myocardial perfusion imaging and emerging applications.

Myocardial perfusion imaging is a well-established noninvasive modality for the diagnosis and prognosis of coronary artery disease. The pharmacologic stress agents adenosine and dipyridamole are widely used in imaging studies, but cause undesirable side effects, like atrioventricular block and bronchospasm, due to their nonselective adenosine receptor activation. Furthermore, the mode of administration of these agents as a bolus infusion is less preferred. Regadenoson, an A2A adenosine receptor selective pharmacologic stress agent was approved in 2008 and is widely used instead of adenosine and dipyridamole. This article reviews regadenosons structure, mechanism of action, advantages over adenosine and dipyridamole, and its role in various patient populations undergoing stress perfusion imaging. Emerging applications where regadenoson could be of potential use are also explored.

Rare Case of Unileaflet Mitral Valve

Unileaflet mitral valve is the rarest of the congenital mitral valve anomalies and is usually life threatening in infancy due to severe mitral regurgitation (MR). In most asymptomatic individuals, it is mostly due to hypoplastic posterior mitral leaflet. We present a 22-year-old male with palpitations, who was found to have an echocardiogram revealing an elongated anterior mitral valve leaflet with severely hypoplastic posterior mitral valve leaflet appearing as a unileaflet mitral valve without MR. Our case is one of the 11 reported cases in the literature so far. We hereby review those cases and conclude that these patients are likely to be at risk of developing worsening MR later in their lives.

Clinical utility of three-dimensional echocardiography for the evaluation of ventricular function.

The evaluation of ventricular function is a core component of 2-dimensional echocardiography (2DE). Given the known limitations of 2DE, a more accurate assessment of ventricular function has long been desired. Three-dimensional echocardiography (3DE) holds promise to fulfill this role while still maintaining the same benefits of low cost, portability, and efficiency of 2DE. Although 3DE has been investigated for over 30 years, the technology has seen little use in the modern clinical echocardiography lab. Although the benefit provided by the additional dimension of 2DE over M-Mode was immediately apparent, the clinical advantages of 3DE over 2DE have been difficult to appreciate. Several reasons for the lack of adoption include the learning curve, concerns about workflow, skepticism about clinical validity, and perceptions that the technology is too unrefined. Nonetheless, the past 2 decades have seen tremendous technical improvements in the field and a wealth of clinically applicable research. In particular, 3DE now has an established role in evaluating left ventricular systolic function. This review highlights the clinical relevancy of 3DE in evaluating ventricular function in terms of the history, relevant data, advantages, and the limitations of current generation 3DE.

Impact of Pre-Existing Left Ventricular Dysfunction on Kidney Transplantation Outcomes: Implications for Patient Selection

BACKGROUND End-stage kidney disease patients with decreased left ventricular ejection fraction (EF) are often denied kidney transplantation (KT) for fear of poor graft and patient survival. METHODS We retrospectively studied all patients who underwent KT at our center between 2001 and 2005 to determine the impact of low EF on outcomes post KT. Low EF was defined as <50% EF by noninvasive cardiac imaging. Follow-up was for 1 year post KT. Outcomes assessed included hospitalization for congestive heart failure (CHF), cardiac events, and renal allograft and patient survival. RESULTS Among 254 patients, 37 had low EF (study group) and 217 had normal EF (≥50%; control group). Post KT, the low EF group had a significantly higher rate of hospitalization for CHF. No significant difference was noted in the rate of cardiac events, graft loss, GFR, and all cause death at 12 months post KT. CONCLUSION Patients with low EF should not be excluded from transplantation, given favorable outcomes.

Eighty-two-year-old man with a systolic murmur

Clinical Introduction An 82-year-old man with a history of coronary artery bypass surgery, hypertension and small bowel gastrointestinal stromal tumour underwent cardiac risk evaluation prior to surgical resection of his tumour. He was asymptomatic from a cardiovascular perspective, but his activity level was less than four metabolic equivalents. Physical examination was notable for a 2/6 systolic murmur at the apex. ECG showed sinus rhythm. A transthoracic echocardiogram was performed (figure 1 and online supplementary video 1). 10.1136/heartjnl-2018-313413.supp1 Supplementary file 1 Figure 1 Transthoracic echocardiography. (A) Mitral valve continuous wave Doppler and (B) tricuspid valve continuous wave Doppler. QUESTION: The findings in figure 1 are most likely due to which of the following? Atrioventricular conduction block. Acute severe aortic regurgitation. Patent ductus arteriosus. Atrial flutter. Severe mitral stenosis.

THE VALUE OF ADDITIONAL TESTING AFTER NON-DIAGNOSTIC STRESS ECHOCARDIOGRAPHY IN PATIENTS PRESENTING WITH CHEST PAIN: A SINGLE-CENTER ANALYSIS

Stress echocardiography (SE) is an important tool in the risk stratification and prognosis of patients with suspected coronary artery disease (CAD). Data regarding outcomes of patients with non-diagnostic SE are mixed. There is significant downstream resource utilization with additional testing in

DOES TRANSIENT ISCHEMIC DILATATION IN THE SETTING OF A NORMAL PHARMACOLOGIC NUCLEAR SCAN REALLY MATTER

Although Transient Ischemic Dilatation (TID) noted on SPECT perfusion images has been a well established marker of significant CAD its clinical significance in presence of otherwise NORMAL SPECT MPI has been recently called in question. We used our laboratory internally validated TID value for

Noninvasive Modalities for Coronary Angiography

Optimal diagnostic quality non-invasive alternatives for visualization of the coronary arteries has been a major goal with the advent of newer cardiovascular imaging mo‐ dalities such as coronary computed tomography angiography (CCTA) and magnetic resonance coronary angiography (MRCA). The challenges in imaging coronaries are ob‐ vious. The technology must be capable of visualizing arteries as small as 1.5 mm to delineate luminal and wall pathology which becomes challenging as many of the arter‐ ies are engulfed in tissue of similar composition. Coronary arteries exhibit rapid mo‐ tion which poses major issues with blurring of images due to substantial limitations of temporal resolution. Invasive coronary angiography current enjoys the best temporal resolution (less than 20 msec ) for real time visualization of coronaries and its branch‐ es but comes with its obvious limitations. CCTA has rapidly risen to this challenge and is already widely employed using 64 slice detector technology and is outstanding for exclusion of CAD with substantial advances in radiation reduction and speed of acquisition. MRCA has made significant improvements in technology which has made coronary imaging less challenging using navigator gating, whole heart imaging and us‐ ing 3Tesla magnets, with the big advantage of no radiation and capability of non-con‐ trast coronary imaging and most of all the promise of a true “ one stop “ comprehensive assessment. However, it is still suboptimal compared to CCTA as dis‐ cussed subsequently in detail. This chapters aims to discuss MRCA and CCTA with regards to coronary imaging and compare and contrast both these imaging modalities with one another and also highlight some emerging comparisons of CCTA to invasive coronary luminal assessment technologies.

Does presence of R wave forces on surface electrocardiogram predict myocardial viability in patients with coronary disease and left ventricular dysfunction? Correlation with cardiac MRI

Background Clinicians use presence of Q waves as a sign of transmural infarction although this is an imperfect marker to predict lack of myocardial viability (MV). We hypothesized that presence of R waves as a marker of electrical activity on surface electrocardiogram (ECG) may be a sensitive marker for presence of MV as determined by delayed enhanced cardiac magnetic resonance (DECMR) imaging.