Showing papers in "Current Cardiology Reports in 2005"

Coarctation of the aorta

Abstract: Coarctation of the aorta is an important, treatable cause of secondary hypertension. Its prevalence varies from 5% to 8% of all congenital heart defects. This condition is most often detected because of a murmur or hypertension found on routine examination. Delayed or absent femoral pulses and an arm/leg systolic blood pressure difference of 20 mm Hg or more in favor of the arms may be considered as evidence for aortic coarctation. The coarctation may be demonstrated on a suprasternal notch two-dimensional echocardiographic view along with increased Doppler flow velocities across the coarctation site. Cardiac catheterization reveals significant systolic pressure gradient (> 20 mm Hg) across the coarctation and angiography demonstrates the degree and type of aortic narrowing. Aortic obstruction may be relieved by surgery or by transcatheter techniques; the latter include balloon angioplasty and stent implantation. In the past, surgery has been used exclusively, but because of morbidity and complications associated with surgery, catheter techniques are increasingly used in the management of aortic coarctation. Balloon angioplasty in children and stents in adolescents and adults are becoming initial therapeutic options for management of coarctation. Studies evaluating long-term follow-up results of the interventional techniques are needed.

Percutaneous approaches to valvular heart disease.

Abstract: Percutaneous endovascular therapy has now become a reality. From early balloon valvotomy for valvular stenosis, technologies have been developed that allow percutaneous replacement of pulmonic and aortic valves and repair of regurgitant mitral valves in selected patients. Following extensive investigations in animals, early clinical reports have shown successes in selected patients. As criteria for patient selection and clinical safety and efficacy trials progress, the role of these new technologies in patient care strategy will become better understood.

Obstructive sleep apnea and hypertension.

Abstract: There is growing evidence of a causal relationship between obstructive sleep apnea (OSA) and hypertension. Untreated OSA may have direct and deleterious effects on cardiovascular function and structure through several mechanisms, including sympathetic activation, oxidative stress, inflammation, and endothelial dysfunction. OSA may contribute to or augment elevated blood pressure levels in a large proportion of the hypertensive patient population. It is important to consider OSA in the differential diagnosis of hypertensive patients who are obese. OSA should be especially considered in those hypertensive patients who respond poorly to combination therapy with antihypertensive medications.

Obesity and lipids.

Abstract: Obesity increases cardiovascular risk through multiple mechanisms. Abdominal (visceral) adiposity is metabolically active and is largely responsible for the atherogenic dyslipidemia, hyperinsulinemia, hypertension, chronic inflammatory state, and prothrombotic state that constitute the metabolic syndrome, and the subsequent increased risk for cardiovascular disease and acute coronary events. Cholesterol guidelines for assessing cardiovascular risk have traditionally focused on low-density lipoprotein (LDL) levels, and reduction of plasma LDL has been shown to reduce cardiovascular events and total mortality. However, the cardiovascular risks associated with the dyslipidemia of obesity--characterized by low levels of high-density lipoprotein; increased triglycerides; increased subfractions of small, dense LDL; and increased levels of apolipoprotein B-100--are also now well recognized.

When is concomitant aortic valve replacement indicated in patients with mild to moderate stenosis undergoing coronary revascularization

Abstract: Mild to moderate aortic stenosis is a common finding in patients presenting for coronary artery bypass grafting (CABG), and its management is controversial. However, review of available data suggests a surgical strategy for these patients. Recent data demonstrate that 1) progression of aortic stenosis is more rapid in those with leaflet calcification; 2) the addition of aortic valve replacement to CABG in patients with mild to moderate stenosis does not increase hospital mortality when compared with bypass surgery alone; 3) hospital mortality for aortic valve replacement after previous bypass surgery has declined in recent years; 4) aortic valve replacement places the patient at risk for prosthesisrelated complications; 5) the limited 10-year survival (competing risk of death) leaves only a minority of individuals with mild aortic stenosis alive and eligible for aortic valve replacement 10 years after bypass surgery; and 6) combined aortic valve replacement and CABG confers a survival benefit in those with moderate aortic stenosis but not in those with mild aortic stenosis. Therefore, in the coronary artery bypass patient with moderate aortic stenosis, leaflet calcification, and life expectancy greater than 5 years, concomitant aortic valve replacement is advised. In contrast, aortic valve replacement is rarely indicated in those with mild aortic stenosis.

Cardiovascular disease in women: sex differences in presentation, risk factors, and evaluation.

Abstract: Cardiovascular disease (CVD) is the leading cause of mortality in women. Pathophysiology, risk factors, clinical presentation, and outcomes of coronary artery disease (CAD) differ in women, and a better understanding of the sex differences in these factors will potentially lead to a slowing of this epidemic in women. Often forgotten, women have higher complication rates post revascularization and higher in-hospital mortality post myocardial infarction compared with men despite a smaller burden of disease in women. Though overall women share the same risk factors as men in the development of CAD, certain risk factors appear to be particularly ominous, such as the presence of diabetes mellitus, low values of high-density lipoprotein cholesterol, high triglycerides, and psychologic depression. Disease detection in advanced CAD is more accurate with stress echocardiography (ECG) and perfusion single-photon emission computed tomography imaging in women than with stress ECG. Subclincial atherosclerotic disease detection with carotid artery intima media thickness assessment provides an opportunity to target preventive measures in women. This article focuses on some of the sex-specific differences.

Effective use of combination lipid therapy.

Abstract: Despite the benefits of statin therapy, low-density lipoprotein cholesterol (LDL-C) management remains suboptimal and many patients do not achieve their recommended target goals. The aim of combination lipid drug therapy in high-risk patients is to achieve LDL-C and non-high-density lipoprotein cholesterol (HDL-C) goals with a minimum of serious adverse effects. Although statins are the drug of first choice, statin monotherapy may be limited by intolerance of dose escalation or failure to attain non-HDL-C goals in those with mixed hyperlipidemia. Statins plus bile acid resins or ezetimibe can achieve greater than 50% reduction in LDL-C, with little or no increase in adverse effects. Fibrates, niacin, and omega-3 fatty acids, when added to statins, can reduce triglycerides, increase HDL-C, and reduce non-HDL-C to a greater extent than statin monotherapy. The safety profile of combination lipid therapy is acceptable, if the global coronary heart disease risk of the patient is high, thus producing a favorable risk to benefit ratio. Careful surveillance of hepatic transaminases, avoidance of gemfibrozil in statin-fibrate combinations, and awareness of statin-concomitant drug interactions is key to safe and efficacious use of combination lipid drug therapy.

The link between obstructive sleep apnea and heart failure: underappreciated opportunity for treatment.

Abstract: Obstructive sleep apnea (OSA) is a newly recognized risk factor for the development of systemic hypertension, ischemic heart disease and congestive heart failure. Mechanisms responsible for these links include OSA-related hypoxemia and arousal from sleep-induced increased sympathetic activity, large negative intrathoracic pressure-induced increased left ventricular transmural pressure gradient, and impaired vagal activity plus oxygen radial formation. Secondary phenomena include increased platelet aggregability, insulin resistance, and endothelial dysfunction with reduced endogenous nitric oxide production. Safe nonpharmacologic, nonsurgical therapy, namely continuous positive airway pressure, can attenuate OSA, and improve cardiac function and quality of life. Searching for signs or symptoms of OSA from the patient (or bed partner), namely loud habitual snoring, apneas, nocturnal choking, orthopnea, paroxysmal nocturnal dyspnea, excessive daytime sleepiness, or cardiovascular disease, which is difficult to control, may reward the curious physician with another treatment avenue.

Diastolic dysfunction and diastolic heart failure: mechanisms and epidemiology.

Abstract: Studies have demonstrated that diastolic dysfunction is frequently present in asymptomatic community-based individuals, especially in the elderly with hypertension, coronary artery disease, and diabetes. The presence of diastolic dysfunction is a predictor for the development of heart failure (HF) and confers a higher risk of mortality. These findings have raised the question of whether treating preclinical diastolic dysfunction will be helpful in preventing or delaying the onset of clinical HF and mortality, as has been proven with treatment of asymptomatic left ventricular systolic dysfunction. In addition, in some individuals, diastolic dysfunction in the presence of a normal ejection fraction is associated with exercise intolerance as well as symptomatic clinical HF, referred to as diastolic HF. Patients with diastolic HF, who are more often elderly women, have a significant mortality and morbidity burden compared with age-matched controls. Studies that further our understanding of mechanisms underlying diastolic dysfunction and diastolic HF will provide potential new targets for development of effective therapies for these conditions.

The future of real-time cardiac magnetic resonance imaging.

Abstract: Dynamic changes in cardiac structure and function are usually examined by real-time imaging techniques such as angiography or echocardiography. MRI has many advantages compared with these established cardiac imaging modalities. However, system hardware and software limitations have limited cardiac MRI to gated acquisitions that are lengthy and often result in failed acquisitions and examinations. Recently, MRI has evolved into a technique capable of imaging dynamic processes in real time. Improvements in hardware, pulse sequences, and image reconstruction algorithms have enabled real-time cardiac MRI with high spatial resolution, high temporal resolution, and various types of image contrast without requiring cardiac gating or breath-holding. This article provides an overview of current capability and highlights key technical and clinical advances. The future prospects of real-time cardiac MRI will depend on 1) the development of techniques that further improve signal to noise ratio, contrast, spatial resolution, and temporal resolution, without introducing artifacts; 2) the development of software infrastructure that facilitates rapid interactive examination; and 3) the development and validation of several new clinical assessments.

Treatment of dyslipidemia in children and adolescents.

Abstract: The early lesions of atherosclerosis begin in childhood, and are related to antecedent cardiovascular disease risk factors. Environmental and genetic factors such as diet, obesity, exercise, and certain inherited dyslipidemias influence the progression of such lesions. The identification of youth at risk for atherosclerosis includes an integrated assessment of these predisposing factors. Treatment starts with a diet low in total and saturated fat and cholesterol, the use of water-soluble fiber and plant sterols, weight control, and exercise. Drug therapy, for example, with inhibitors of hydroxymethylglutaryl CoA reductase, bile acid sequestrants, and cholesterol absorption inhibitors, can be considered in those with a positive family history of premature coronary artery disease and a low-density lipoprotein cholesterol above 160 mg/dL, after dietary and hygienic measures. Candidates for drug therapy often include those with familial hypercholesterolemia, familial combined hyperlipidemia, the metabolic syndrome, polycystic ovarian syndrome, type I diabetes, and the nephrotic syndrome. We review the safety and efficacy of dietary and drug therapy, and propose an updated diagnostic and therapeutic algorithm that includes the metabolic syndrome. The early identification and treatment of youth with dyslipidemias is likely to retard the atherosclerotic process.

Small vessel strokes.

Abstract: Small vessel disease is a common cause of cerebrovascular disease. It is responsible for ischemic and hemorrhagic strokes, cognitive decline, and asymptomatic disease. Millions of Americans are affected by silent strokes and white matter abnormalities. Lacunar stroke is the most common manifestation. Despite its importance, small vessel strokes remain understudied. There is a need for research focused on this prevalent stroke subtype to define optimal interventions to prevent stroke recurrence and cognitive impairment.

Sudden cardiac death without structural heart disease: update on the long QT and Brugada syndromes.

Abstract: The long QT syndrome (LQTS) and the Brugada syndrome (BrS) are the most common genetic causes of malignant ventricular arrhythmias and sudden cardiac death in young patients with normal cardiac morphology. To date, more than 250 different mutations in seven genes have been identified as causing LQTS, whereas the only gene identified to be linked to BrS is SCN5A. In both syndromes, genespecific mutations have been shown to be associated with specific phenotypic expressions. Risk stratification in LQTS and BrS is based mainly upon a constellation of electrocardiographic findings and a history of prior symptoms. In patients identified as high risk for arrhythmic mortality, the implantable cardioverter defibrillator is the most effective treatment and has been shown to provide near-complete protection during long-term follow-up.

Evaluation of intracardiac shunts with cardiac magnetic resonance

Abstract: Intracardiac shunts including atrial septal defect, ventricular septal defect, endocardial cushion defects, and surgical baffles may be identified, localized, and quantified using cardiac MRI methods. Both dark-blood and bright-blood techniques are helpful to identify anatomy. Contrast enhancement is especially useful for identifying associated vascular anomalies. Dynamic first-pass contrast agent signal-time studies may demonstrate rapid recirculation and shunting. Volumetric and phase contrast cine methods are useful to quantify flow. Pulmonary to systemic (Qp/Qs) flow ratios may be calculated noninvasively by comparing the pulmonary artery flow to the aortic flow measurement.

Genetic variation and lipid metabolism: Modulation by dietary factors

Abstract: Cardiovascular diseases (CVD) result from complex interactions between genetic and environmental factors The evidence supports that gene-environment interactions modulate plasma lipid concentrations and potentially CVD risk The findings from studies examining gene-diet interactions and lipid metabolism have been promising Several loci (eg, APOA1, APOE, LIPC) are providing proof of concept for the application of genetics in the context of personalized nutrition for CVD prevention The spectrum of candidate genes has been expanding to incorporate those involved in intracellular lipid metabolism (eg, iPPARs, CYP7A1) However, the practical application of these findings is not ready for prime time There is a compelling need for replication using a higher level of scientific evidence Moreover, we need to evolve from the simple scenarios examined nowadays (ie, one single dietary component, SNP, and risk factor) to more realistic situations involving multiple interactions In summary, there is need for both large population studies and well-standardized intervention studies

Resistance to antiplatelet therapy

Abstract: Cardiovascular mortality continues to be high and events continue to occur in patients taking antiplatelet medications. Aspirin and clopidogrel have become integral parts of management in patients with coronary artery disease and after percutaneous angioplasty. However, the platelet responses to aspirin and clopidogrel are not uniform. Diminished or lack of response to these agents has been termed aspirin resistance and clopidogrel resistance. These phenomena have tremendous clinical significance as together they may occur in more than 50% of all patients on chronic therapy with aspirin or clopidogrel. Postulated mechanisms of aspirin and clopidogrel resistance include alterations in genetic, pharmacokinetic, and platelet properties. There is a dearth of information in regard to their clinical significance, methods to test them, and strategies to treat them. Further research is necessary in these areas to identify these patients and treat them appropriately.

Molecular cardiovascular imaging.

Abstract: Imaging with radionuclides has historically played an important role in detection of cardiovascular disease as well as in risk stratification and prognostication. With the growth of molecular biology have come new therapeutic interventions and the requirement for new diagnostic imaging approaches. Noninvasive targeted radiotracer-based strategies require the development of new instrumentation to meet these needs. This progress has been made possible with the availability of many technologic advances, which include dedicated micro single-photon emission computed tomography (SPECT) and micro positron emission tomography (PET) hybrid systems for small animal imaging. This review is a brief overview on the subject of molecular imaging. Basic concepts of molecular imaging are reviewed, followed by description of current technologic advances, and current applications to evaluate ischemic heart disease and potential therapeutic intervention. The emphasis is on the use of both SPECT and PET radiotracers, although other imaging modalities are also briefly discussed.

Cardiovascular magnetic resonance and the evaluation of heart failure

Abstract: Cardiovascular magnetic resonance (CMR) has established itself as probably the single best way of phenotyping the failing heart. It is the accepted gold standard for measuring cardiac function, volumes, and mass, but within the same scan session additional techniques are available for greater definition. Tissue characterization with the contrast agent gadolinium is well validated and allows the precise visualization and quantification of myocardial infarction. This can be used for viability assessment and to determine heart failure etiology. Dobutamine stress CMR and CMR perfusion hold advantages over conventional techniques. The new frontiers of CMR in heart failure hold the promise of unique insights quantifying myocardial iron, nonischemic fibrosis, microvascular perfusion, plaque characterization, and CMR-targeted intervention. The development and validation of these techniques represent major research challenges for the future. From a clinical perspective, an equal challenge is in increasing the availability of the modality for patients and physicians.

Transposition of the great arteries: long-term outcome and current management

Abstract: There is a large group of young adults who survived atrial baffle repair of transposition of the great arteries. Most survivors are asymptomatic, although nearly all have decreased exercise capacity. Loss of sinus rhythm and atrial arrhythmias are common and increase with age. There is concern about the ability of the right ventricle to function long term as a systemic pump, and recent publications have highlighted right ventricular dysfunction in this patient population. Sudden death and congestive heart failure are the main causes of death, and outcomes beyond 30 years are unknown. Pulmonary artery banding, late arterial switch, and cardiac transplantation are employed when intractable arrhythmias or right ventricular failure threaten survival or quality of life.

Stroke in Black Americans.

Abstract: Black Americans bear a disproportionate stroke burden in the United States compared with other racial and ethnic groups. Poor stroke awareness, higher vascular risk factor burden, limited access to care, mistrust of the medical system, and inequities in diagnostic testing and treatment usage may account for some of the disparity. In addition, blacks have historically been under-represented in observational studies and clinical trials of stroke prevention and treatment. Therefore, our knowledge regarding stroke in black Americans is somewhat limited. This article provides an update on developments in our understanding regarding stroke in this at-risk population.

Pregnancy in women with congenital heart disease.

Abstract: Congenital heart disease is the most common form of structural heart disease affecting women of childbearing age in developed countries. Pregnancy in these patients is associated with an increased risk to both mother and fetus. Appropriate prepregnancy evaluation and counseling is recommended to assess the pregnancy-related maternal and fetal risk and to identify patients who should avoid pregnancy. Once pregnancy occurs, cardiovascular reevaluation is generally recommended; the frequency is individualized. Monitoring during delivery may be necessary and the post-partum period is a concern in select individuals. Data regarding the outcome of pregnancy in patients with operated congenital cardiac defects are available. Individualized care is mandatory.

Management of diuretic-refractory, volume-overloaded patients with acutely decompensated heart failure.

Abstract: Fluid overload is a common presentation for decompensated heart failure, yet management strategies are poorly defined because of relatively few randomized clinical trials that delineate an optimal strategy. Patients refractory to diuretic therapy may be considered for treatment with inotropes or vasodilators, and others may be considered for venovenous ultrafiltration. The rationale for use of each therapy is reviewed.

Use of cardiac magnetic resonance to assess viability.

Abstract: The accurate differentiation of viable and nonviable myocardium is crucial for therapy planning in patients with coronary artery disease and left ventricular dysfunction. Traditional techniques such as echocardiography, positron emission tomography, single photon emission computed tomography, and dobutamine echocardiography have established roles. Cardiac MRI (CMR) is a rapidly emerging new modality that is used at an increasing number of medical centers in Europe and the United States. This review describes the role of CMR for the assessment of myocardial viability in the setting of acute and chronic ischemic ventricular dysfunction.

An Update on Renovascular Hypertension

Abstract: Renovascular hypertension (RVH) represents a secondary and potentially remediable form of hypertension. Elevated blood pressure is only one of a broad array of pathophysiologic consequences that are associated with decreased renal perfusion. Our ability to accurately and noninvasively detect stenotic lesions within the renal artery is growing. However, functional assessment of renal parenchyma and hemodynamic significance of renal artery lesions is still limited. Advances in endovascular techniques spurred interest in the concept of ischemic nephropathy and the effect of renal artery revascularization on renal function. Despite the relative frequency of atherosclerotic renal artery stenosis (ARAS), there currently is no consensus on the most appropriate therapy. In this article, we focus on the two most common causes of RVH, ARAS and fibromuscular dysplasia. We discuss the therapeutic strategies, disease mechanisms, clinical findings, evolving trends, and developments.

Quantitative single-photon emission computed tomography imaging.

Abstract: Over the past decade, quantitation of cardiac single-photon emission computed tomography (SPECT) data, once limited to perfusion assessment, has been extended to global and regional function assessment for both the left and the right ventricle, as well as to measurement of additional cardiac parameters of diagnostic and prognostic interest. A number of commercially available quantitative algorithms exist, based on different mathematic operators and with varying degrees of automation, that are capable of providing accurate and reproducible results. This article describes the many quantitative cardiac SPECT measurements available today, defining them in terms of validation, practical use, and limitations.

Prophylaxis and management of postoperative atrial fibrillation

Abstract: Atrial fibrillation (AF) is the most common cardiac arrhythmia seen after cardiac surgery. It is associated with prolongation of hospital stay, postoperative complications, stroke, mortality, and increased hospital cost. Several prevention strategies have been proven effective in reducing postoperative AF; in addition, active prevention of postoperative AF is associated with a decrease in the length of hospital stay and a reduction trend in hospital costs. In patients with postoperative AF, restoration and maintenance of sinus rhythm and rate control are adequate treatment alternatives in the majority of cases. In severely symptomatic or hemodynamically compromised patients urgent cardioversion is needed. Adequate oral anticoagulation may be indicated for a limited period of time.

Palpitations: a proper evaluation and approach to effective medical therapy.

Abstract: Palpitations are a common complaint seen in the outpatient setting and the vast majority are benign, although they are occasionally a manifestation of potentially life-threatening conditions. We offer a step-wise guide to the evaluation and management of these patients with the primary goal to identify patients at highest risk for serious arrhythmias. We offer a brief overview of effective management of the varied causes of palpitations.

Primary aldosteronism: diagnostic and therapeutic considerations.

Abstract: Recent evaluations indicate that primary aldosteronism (PA) is common in patients with hypertension. In patients with mild to moderate hypertension the prevalence of PA is 5% to 10%, whereas in subjects with resistant hypertension the prevalence is approximately 20%. As such, PA has become the most common secondary cause of hypertension. Such high prevalence rates are distinctly different from earlier assessments in which PA was found to be rare, with a prevalence of generally less than 1% of hypertensive patients. Why PA is seemingly so much more common now than when first described remains unknown. Accurate identification of PA allows for specific therapy with aldosterone antagonists or with surgical resection of aldosteroneproducing adenomas. Determination of the plasma aldosterone to plasma renin activity ratio is an effective screen for PA in that it has a high negative predictive value even in the setting of ongoing antihypertensive therapy. Its specificity, however, is low such that a high ratio is suggestive of PA but must be confirmed by demonstration of high and autonomous secretion of aldosterone.

Hyperacute imaging of ischemic stroke: role in therapeutic management.

Abstract: Ischemic stroke remains a significant cause of morbidity and mortality. Current therapeutic options for acute ischemic stroke include intravenous thrombolysis and endovascular approaches for recanalization of proximal arterial occlusion. The rapid identification of underlying stroke etiology or mechanism may facilitate selection criteria for emergent therapy. Hyperacute imaging plays an integral role in the delineation of stroke pathophysiology and the formulation of rational stroke therapy. Hyperacute imaging of ischemic stroke may demonstrate proximal vascular occlusion, compensatory collateral circulation, residual or collateral tissue perfusion, and the differentiation of ischemic core from penumbral regions. Characterization of the ischemic field, including core and penumbra, with various mismatch models on multimodal computed tomography or MRI may refine current therapeutic strategies for cerebral ischemia. The diagnostic and therapeutic role of hyperacute imaging has emerged as a pivotal component in the evaluation and management of ischemic stroke.

Approach to antiarrhythmic therapy in patients with ICDs and frequent activations.

Abstract: Patients with an implantable defibrillator may require concomitant antiarrhythmic drug therapy to reduce therapy from the device, especially shocks from the device. New evidence suggests that amiodarone, in combination with β-blockade, is the most effective treatment to reduce the frequency of defibrillator therapies, but sotalol and azimilide have also been shown to be effective. Electrical storm is a serious condition that occurs in 20% of patients living with a defibrillator, and its management requires a complex approach to the patient.