Publications by authors named "Merrill Stewart"

Background: On legacy 2D positron emission tomography (PET) systems utilizing a 50 mL/min Rb-82 profile, test-retest precision of quantitative perfusion is ∼10%. It is unclear whether Rb-82 infusion rate significantly impacts quantitative perfusion and/or image quality on modern analog 3D PET-CT systems. We aimed to determine whether the Rb-82 infusion profile significantly impacts test-retest precision of quantitative perfusion, perfusion metrics, and/or image quality on a modern analog 3D PET-CT scanner.

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Purpose Of Review: Hypertension (HTN) that can be attributed to a particular source is known as secondary HTN (SH). Often, SH is difficult to control and thus referred to as resistant HTN, although the two terms are not mutually exclusive.

Recent Findings: A common theme across several contributors to SH are coactivation of the sympathetic drive and hormonal changes, independent of hormonal axis activation.

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Purpose Of Review: The current article reviews obstructive forms of hypertrophic cardiomyopathy and associated morphologic cardiac abnormalities. It focuses on echocardiographic imaging of the left ventricular (LV) outflow tract obstruction, its evaluation, prognostication, and differentiation from other conditions mimicking obstructive hypertrophic cardiomyopathy.

Recent Findings: Symptomatic patients with LV outflow tract (LVOT) gradients at least 50 mmHg on maximally tolerated medical therapy are candidates for advanced therapies.

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Purpose Of Review: Hypertensive crisis (HTN-C) is a condition of increasing prevalence. It carries significant morbidity and mortality, and prompt recognition and treatment are crucial. There is a paucity of controlled trials, so a working knowledge of the most recent literature in the area of HTN-C is helpful.

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: Resting myocardial blood flow (rMBF) within regions of myocardial scar as measured by positron emission tomography (PET) has not yet been assessed with the radiotracer Rubidium (Rb) or correlated with scar thickness. Cardiac magnetic resonance imaging (cMRI) offers high spatial resolution and identifies myocardial scar with late gadolinium enhancement (LGE). Using Rb PET, we sought to characterize rMBF in regions of myocardial scar of varying thicknesses determined by cMRI.

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• LV IMD is a rare complication of blunt chest trauma. • Associated papillary muscle avulsion led to severe MR. • Transthoracic echocardiography provides a rapid diagnosis of this rare entity.

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Prothesis-patient mismatch (PPM) occurs when there is a mismatch between the effective orifice area (EOA) of the prosthetic valve and the required cardiac output to meet the need of the patient's body surface area (BSA). The clinical threshold for PPM occurs when the indexed effective orifice area (iEOA) is ≤0.65 cm/m for the aortic valve prosthesis, and ≤ 1.

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Purpose Of Review: Preeclampsia complicates 3-5% of first and 15% of subsequent pregnancies. This study reviews the evidence of increase cardiovascular risk in these women.

Recent Findings: Women with preeclampsia are at two-fold higher risk for development of coronary artery disease, stroke and death, and four-fold increased risk of heart failure.

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Chagas disease (CD) is a tropical vector-borne infection caused by the protozoan parasite Trypanosoma cruzi (T. cruzi), also known as American Trypanosomiasis. It is considered endemic in all South and Central America and in this past decades its becoming a burden particularly in the United States and Europe due to human migration.

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Hypertension (HTN) is a major modifiable risk factor for cardiovascular disease (CVD) morbidity and mortality. The left ventricle (LV) is a primary target for HTN end-organ damage. In addition to being a marker of HTN, LV geometrical changes: concentric remodeling, concentric or eccentric LV hypertrophy (LVH) are major independent risk factors for not only CVD morbidity and mortality but also for all-cause mortality and neurological pathologies.

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Purpose Of Review: Resistant hypertension is defined as blood pressure above patient goal despite three different antihypertensive agents at optimal dose including a diuretic. Resistant hypertension is increasingly common issue in clinical practice and it is a major risk factor of cardiovascular disease.

Recent Findings: All patients with resistant hypertension should be evaluated for possible correctable factors associated with pseudoresistance, such as poor adherence, white coat hypertension and suboptimal measurement of blood pressure.

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Purpose Of The Review: Pharmacology remains the mainstay of treatment for hypertension across the globe. In what may seem like a well-trodden field, there are actually an exciting array of new pathways for the treatment of hypertension on the horizon. This review seeks to discuss the most recent research in ongoing areas of drug development in the field of hypertension.

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Acute ischemic stroke is a condition with considerable mortality and morbidity. When used appropriately, Transesophageal Echocardiography (TEE) can be an incredibly useful tool to identify potential causes of stroke and guide management. The crucial distinction in this modality lies in separating common incidental findings from those likely to have contributed to ischemic stroke.

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Left ventricular hypertrophy (LVH) was one of the earliest studied echocardiographic characteristics of the left ventricle. As the myriad of measurable metrics has multiplied over recent years, this reliable and relevant variable can often be overlooked. In this paper, we discuss appropriate techniques for accurate analysis, underlying pathophysiology, and the contributions from various risk factors.

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With improved surgical techniques and medical therapies, many patients who are born with complex congenital heart defects are now living well into adulthood. As these patients age, an increasingly common cause of mortality is sudden cardiac death (SCD) from ventricular tachyarrhythmias. The implantable cardioverter-defibrillator (ICD) is a therapy with the ability to prevent some of these deaths; however, there are many diagnostic and technical challenges that remain in the congenital heart disease (CHD) population.

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Purpose Of Review: Hypertension (HTN) is a widespread and growing disease, with medication intolerance and side-effect present among many. To address these obstacles novel pharmacotherapy is an active area of drug development. This review seeks to explore future drug therapy for HTN in the preclinical and clinical arenas.

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Periprocedural management of anticoagulation for cardiac device implantation has evolved over the past 20 years. The traditional paradigm of vitamin K antagonist interruption with heparin bridging has now been shown to be less safe than continuation of vitamin K antagonists at therapeutic levels. Dual antiplatelet therapy during device implantation poses substantial risk but is often necessary.

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Cardiac valvular disease as consequence of radiation and chemotherapy during treatment for malignancy is growing in its awareness. While the overwhelming emphasis in this population has been on the monitoring and preservation of left ventricular systolic function, we are now developing a greater appreciation for the plethora of cardiac sequelae beyond this basic model. To this end many institutions across the country have developed cardio-oncology programs, which are collaborative practices between oncologists and cardiologists in order to minimize a patient's cardiovascular risk while allowing them to receive the necessary treatment for their cancer.

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Endovascular treatment of vertebral artery stenosis (VAS) is a safe and effective technique for treating symptoms caused by posterior circulation ischemia with high technical and clinical success rates, low complication rates and durable long-term results. Variable restenosis rates have been reported in the literature with small improvements demonstrated using drug eluting stents. Although there is insufficient evidence from randomized trials to demonstrate superiority of endovascular compared to optimal medical therapy for the treatment of this disease, patients who fail medical therapy should be considered for endovascular stenting for symptomatic VAS.

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Background: Mitral regurgitation (MR) is the second leading cause of valvular heart disease in the United States behind aortic stenosis. The percutaneous repair of the mitral valve (MitraClip, Abbott, Inc.) has been approved in the United States since 2013 as an alternative to traditional mitral valve surgery.

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Recent therapeutic trials regarding the management of acute heart failure (AHF) failed to demonstrate the efficacy of newer therapeutic modalities and agents. Low- versus high-dose and continuous administration of furosemide were shown not to matter. Ultrafiltration was not found to be more efficacious than sophisticated diuretic therapy including dose-adjusted intravenous furosemide and metolazone.

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