Items in AFP with MESH term: Death, Sudden, Cardiac
ABSTRACT: In approximately 5 percent of sudden cardiac deaths, no demonstrable anatomic abnormality is found. Some cases are caused by sudden arrhythmia death syndrome. A prolonged QT interval is a common thread among the various entities associated with sudden arrhythmia death syndrome. A number of drugs are known to cause QT prolongation (e.g., terfenadine), as are hypokalemia, hypomagnesemia, myocarditis, and endocrine and nutritional disorders. Recently, attention has focused on a group of inherited gene mutations in cardiac ion channels that cause long QT syndrome and carry an increased risk for sudden death. Some of the highest rates of inherited long QT syndrome occur in Southeast Asian and Pacific Rim countries. The median age of persons who die of long QT syndrome is 32 years; men are predominately affected. In addition to a prolonged QT interval, which occurs in some but not all persons with long QT syndrome, another characteristic electrocardiographic abnormality is the so-called Brugada sign (an upward deflection of the terminal portion of the QRS complex). Most cardiac events are precipitated by vigorous exercise or emotional stress, but they also can occur during sleep. Torsades de pointes and ventricular fibrillation are the usual fatal arrhythmias. Long QT syndrome should be suspected in patients with recurrent syncope during exertion and those with family histories of sudden, unexpected death. Unfortunately, not all persons with long QT syndrome have premonitory symptoms or identifiable electrocardiographic abnormalities, and they may first present with sudden death. Beta blockers, potassium supplements, and implantable defibrillators have been used for treatment of long QT syndrome. Identifying the specific gene mutation in a given patient with long QT syndrome can help guide prophylactic therapy.
ABSTRACT: Arrhythmogenic right ventricular dysplasia (ARVD) is a disorder in which normal myocardium is replaced by fibrofatty tissue. This disorder usually involves the right ventricle, but the left ventricle and septum also may be affected. Although the exact prevalence of ARVD is unknown, it is thought to occur in six per 10,000 persons in certain populations. After hypertrophic heart disease, it is the number one cause of sudden cardiac death in young persons, especially athletes. Patients with ARVD are usually men younger than 35 years who complain of chest pain or rapid heart rate. In some cases, sudden cardiac death is the first presentation. The initial diagnosis of ARVD is based on the presence of major and minor criteria established in 1994. Further confirmation of the diagnosis includes noninvasive studies, such as echocardiography and magnetic resonance imaging of the heart, and invasive studies such as ventricular angiography and endomyocardial biopsy. Patients with ARVD are treated initially with antiarrhythmic agents with serious consideration for automatic implantable cardioverter-defibrillator placement. In patients with persistent symptomatic arrhythmias, radiofrequency ablation, ventriculotomy, or even cardiac transplant may be necessary.
ABSTRACT: Thousands of young athletes receive preparticipation evaluations each year in the United States. One objective of these evaluations is to detect underlying cardiovascular abnormalities that may predispose an athlete to sudden death. The leading cardiovascular causes of sudden death in young athletes include hypertrophic cardiomyopathy, congenital coronary artery anomalies, repolarization abnormalities, and Marfan syndrome. Because these abnormalities are rare and difficult to detect clinically, it is recommended that family physicians use standardized history questions and examination techniques. Athletes, accompanied by their parents, if possible, should be asked about family history of cardiac disease and sudden death; personal cardiac history; and exercise-related symptoms, specifically syncope, chest pain, and palpitations. The physical examination should include blood pressure measurement, palpation of radial and femoral pulses, dynamic cardiac auscultation, and evaluation for Marfan syndrome. Athletes with "red flag" signs or symptoms may need activity restriction, special testing, and referral if the diagnosis is unclear.
ABSTRACT: Sudden cardiac death is a major public health problem, affecting 500,000 patients in the United States annually. An implantable cardioverter-defibrillator (ICD) can terminate malignant ventricular arrhythmias and has been shown to improve survival in high-risk populations. Although sudden cardiac death is a heterogeneous condition, left ventricular ejection fraction of 35 percent or less remains the single best factor to stratify patients for prophylactic ICD implantation, and randomized trials have shown mortality benefit in this population. Therefore, in patients with heart disease, assessment of ejection fraction remains the most important step to identify patients at risk of sudden cardiac death who would benefit from ICD implantation. Physician understanding of each patient’s ICD type, indication, etiology of heart disease, and cardiovascular status is essential for optimal care. If the ICD was placed for secondary prevention, the circumstances relating to the index event should be explored. Evaluation of defibrillator shocks merits careful assessment of the patient’s cardiovascular status. Consultation with a subspecialist and interrogation of the ICD can determine if shocks were appropriate or inappropriate and can facilitate management.
Outpatient Approach to Palpitations - Article
ABSTRACT: Palpitations are a common problem seen in family medicine; most are of cardiac origin, although an underlying psychiatric disorder, such as anxiety, is also common. Even if a psychiatric comorbidity does exist, it should not be assumed that palpitations are of a noncardiac etiology. Discerning cardiac from noncardiac causes is important given the potential risk of sudden death in those with an underlying cardiac etiology. History and physical examination followed by targeted diagnostic testing are necessary to distinguish a cardiac cause from other causes of palpitations. Standard 12-lead electrocardiography is an essential initial diagnostic test. Cardiac imaging is recommended if history, physical examination, or electrocardiography suggests structural heart disease. An intermittent event (loop) monitor is preferred for documenting cardiac arrhythmias, particularly when they occur infrequently. Ventricular and atrial premature contractions are common cardiac causes of palpitations; prognostic significance is dictated by the extent of underlying structural heart disease. Atrial fibrillation is the most common arrhythmia resulting in hospitalization; such patients are at increased risk of stroke. Patients with supraventricular tachycardia, long QT syndrome, ventricular tachycardia, or palpitations associated with syncope should be referred to a cardiologist.