Congenital anomalies of coronary arteries: role in the pathogenesis of sudden cardiac death.

After hypertrophic cardiomyopathy, coronary artery anomalies of origin from the wrong sinus of Valsalva are the second most common cause of sudden death on the athletic field in the USA. Although the right coronary artery arising from the left coronary sinus (ARCA) is four times as common as the left coronary artery arising from the anterior sinus (ALCA), it is the latter that is by far the more common cause of sudden death with or shortly after vigorous physical activity. Of the four types of ALCA, the interarterial type, where the left coronary artery passes anteriorly between the aorta and the right ventricular outflow tract, is the only type that places the patient at risk of sudden death. Another feature of this syndrome is the fact that sudden death occurs associated with or shortly after vigorous exercise and is very unusual after the patient is > 35 years of age. The mechanism by which there is sudden occlusion of the interarterial coronary artery is at present unknown, although there are a number of hypotheses involving the oblique passage of the vessel as it leaves the aorta. Sudden death is probably rare considering the number of people who have these anomalies. Symptoms premonitory to a fatal event such as exertional syncope, chest pain, or palpitations are probably common in patients at risk, and surgical correction is indicated in symptomatic patients at any age. In older asymptomatic patients, surgery is not recommended, since the incidence of sudden death in this age group is extremely small. In asymptomatic young patients, a stress test, preferably with radioisotope myocardial perfusion imaging or stress echocardiogram, should be done and surgical correction performed in those with ischemia provoked in the appropriate myocardial region. Since there is evidence that in patients who have survived a potentially fatal event, it is rare to be able to provoke ischemia with equal or greater exercise than had precipitated the malignant arrhythmia, the decision to surgically correct an asymptomatic young patient, serendipitously found to have ALCA, who has a negative exercise test, is debatable. Any decision for surgery in such patients should be made only after a full discussion of the risks pro and con surgery with the patient and the patient's family.

Cardiovascular safety of sildenafil citrate (Viagra): an updated perspective.

Sildenafil citrate (Viagra; Pfizer Inc, New York, NY) relaxes vascular smooth muscle, resulting in modest reductions in blood pressure that are insufficient to stimulate a reflex increase in heart rate. These blood pressure reductions are similar for healthy men and men with coronary artery disease (CAD) or who use antihypertensive drugs. Sildenafil does not affect the force of cardiac contraction, and cardiac performance is unaffected. Sildenafil is mildly vasodilating in the coronary circulation and does not increase the risk of ventricular arrhythmia. During exercise and recovery, sildenafil does not cause clinically significant alterations in hemodynamic parameters in men with CAD, and it has no negative effects on coronary oxygen consumption, ischemia, or exercise capacity. Clinical trial data from >13,000 patients, 7 years of international postmarketing data, and observational studies of >28,000 men in the United Kingdom and 3813 men in the European Union reveal that (1) there are no special cardiovascular concerns when sildenafil is used in accordance with product labeling and (2) the risk for serious events such as myocardial infarction or death is not increased. However, because safety has not been established in patients with recent serious cardiovascular events, hypotension or uncontrolled hypertension, or retinitis pigmentosa, physicians should consult their current local prescribing information before prescribing sildenafil for these patients. Among men with erectile dysfunction treated with sildenafil, the adverse event profile is similar overall to that in men with comorbid cardiovascular disease (CVD), it is similar between those with and without CAD, and it is similar between those who take and those who do not take antihypertensive drugs (regardless of the number or class). In a controlled interaction study of sildenafil and amlodipine, the mean additional reduction in supine blood pressure was 8 mm Hg systolic and 7 mm Hg diastolic. Sildenafil should be used with caution in patients who take alpha-blockers because coadministration may lead to symptomatic hypotension in some individuals. When sildenafil is coadministered with an alpha-blocker, patients should be stable on alpha-blocker therapy before initiating sildenafil treatment and sildenafil should be initiated at the lowest dose. Also, in the absence of information specific to mixed alpha/beta blockers, such as carvedilol and labetalol, similar care should be taken as for alpha-blockers. Sildenafil potentiates the hypotensive effects of nitrates, and its administration to patients who are using organic nitrates in any form, either regularly or intermittently, is contraindicated. Before prescribing sildenafil, physicians should carefully consider whether their patients with underlying CVD could be affected adversely by resuming sexual activity. Management recommendations based on cardiovascular risk, from the Second Princeton Consensus Conference, are presented.

Asymptomatic adult patients with aortic stenosis: should they ever have aortic valve replacement?

Presently, conventional wisdom is that an asymptomatic patient, even with severe aortic stenosis (AS), can be followed medically. The basis for this recommendation is that sudden death as the first "symptom" in an asymptomatic patient is rare. Unfortunately, symptoms are subjective and can be ignored or explained away by both patient and physician, and once symptoms are recognized, sudden death accounts for at least one third of the deaths from AS in unoperated patients. There is evidence that once AS becomes severe, ischemia and fibrosis occur rapidly, setting up the possibility of heart failure and sudden death even after successful valve replacement. Aortic valve replacement should be performed before extensive fibrosis occurs. Multiple studies have shown that in severe AS, symptoms will occur rapidly when there is heavy valve calcification, an aortic valve area <0.8 cm, an annual rate of progression of aortic valve velocity of >/=0.3 m/sec, or a positive exercise stress test. These findings are excellent evidence that asymptomatic patients with severe AS and any of the above findings should be considered for aortic valve replacement.

Sexual activity and cardiac risk.

Endothelial dysfunction underlies both atherosclerosis and erectile dysfunction (ED). Therefore, the incidence of coronary artery disease (CAD) is inevitably increased in patients with ED. Patients with ED, who are typically unable to develop or maintain an erection, are able to engage in sexual activity when treated with phosphodiesterase 5 inhibitors. Acute coronary syndromes and cardiac sudden death are precipitated by either vulnerable plaque erosion or rupture, or by the development of sudden myocardial ischemia. The physical activity of sexual intercourse is associated with increased myocardial oxygen demand (MVo(2)) and increased sympathetic nervous system activation, both of which can result in myocardial ischemia in the presence of CAD. The effect of sexual activity on total body oxygen consumption (Vo(2)) and MVo(2) has been studied in the past, but not extensively. Available research shows that sexual intercourse increases Vo(2) to a modest extent. As studied, Vo(2) is increased modestly to 3 to 5 metabolic equivalents. Further, this increase in Vo(2) lasts only for a brief period. The small increase in the incidence of myocardial infarction that accompanies sexual activity within 2 hours of onset is likely related to sympathetic activation and to an increase in MVo(2). The evidence for this hypothesis is reviewed in this article.

Sexual activity and cardiovascular disease.

Cardiovascular disease and erectile dysfunction (ED) are frequently comorbid. Therefore, it is important to consider the risk of renewed sexual activity after successful treatment of ED in men with cardiovascular disease. This article reviews the limited existing knowledge of the metabolic and cardiovascular demands of sexual activity. Evidence suggests that there is a small increase in cardiovascular risk related to sexual activity. Overall, however, the metabolic and cardiovascular demands of sexual activity are modest, and regular physical activity can almost eliminate the increase in risk occurring during sex. In addition, it is unlikely that any direct effect of a phosphodiesterase 5 inhibitor increases cardiovascular risk in patients with cardiovascular disease, absent the coadministration of organic nitrates.