Andersons pediatric cardiology 1085

communication is large and does not cause a continuous murmur Even with careful aortography, this condition may be misdiagnosed Echocardiography should now help to avoid this error Major aortopulmonary collateral arteries, pulmonary arteriovenous fistulas, and collateral arteries associated with coarctation, all cause continuous murmurs These seldom cause diagnostic problems because of the general clinical picture and the location of the murmur Other causes of continuous murmurs heard in the chest include ruptured sinus of Valsalva, peripheral pulmonary arterial stenosis, common arterial trunk, coronary artery fistulas, the supracardiac form of totally anomalous pulmonary venous connection, mitral atresia, surgically created systemic-to-pulmonary arterial shunts, and rarely anomalous origin of the left coronary artery from the pulmonary trunk Prolapse of an aortic valvar leaflet into a ventricular septal defect may also simulate persistent patency of the duct Most, if not all, of these potential pitfalls can be avoided by careful clinical evaluation and good echocardiography Natural History Like most congenital cardiac malformations, reliable information about the natural history of untreated patients with a persistently patent duct is nonexistent Available data stem from the short period of time that elapses between the condition being diagnosed with any frequency and to its being relieved by an operation Campbell75 attempted an overview of the natural history, based on his own extensive clinical experience and on the literature Inevitably, such calculations tend to overemphasize the number of patients who experience events, be they favorable or adverse and underestimate the number of patients with an asymptomatic and undetected duct Spontaneous Closure By definition, a persistent duct is one that remains open beyond 3 months in an infant born at full term Delayed closure in premature infants, or that occurring within the first 3 months, is therefore excluded from consideration in this section Campbell75 analyzed four series of patients in which 11 examples of spontaneous closure occurred over 1842 patient-years, giving a rate of 0.6% per annum However, several of the examples were based on quite tenuous clinical impressions In none was catheterization performed before and after the event The figure calculated by Campbell is almost certainly an overestimate He did not suggest that surgery should be delayed except, perhaps, in patients with small shunts and signs that the duct was already closing Few cardiologists would now agree even with these exceptions The capricious nature in understanding whether spontaneous closure is common has been nicely summarized recently by Julien Hoffman.76 Effect on Life Expectancy By combining four series, consisting mainly of “unselected” schoolchildren with a persistent duct, Campbell deduced a mortality rate of 0.42% per annum during the first 2 decades of life Thereafter he calculated mortality rates per year as 1% to 1.5% in the third decade, 2% to 2.5% in the fourth, and 4% for each subsequent year These calculations indicate that one-third of patients with a persistent duct die by the age of 40 years, in contrast to less than 5% of the normal population Many of the figures are based on data obtained in the era before antibiotics were available Because infective endocarditis is a major cause of death, the impact of antibiotics must also be taken into account These figures agree fairly well with age at death as reported in necropsy series For example, Abbott77 found the mean age at death, having excluded those who died in infancy, to be 30 years, and in another series, the mean age was 36.5 years.78 Despite this agreement, the fact remains that calculations from autopsy series, and from clinical series, are extrapolations from rather small numbers They undoubtedly exaggerate the adverse aspects of the natural history Complications The important complications of persistent patency of the duct include congestive heart failure, infective endarteritis, pulmonary vascular disease, aneurysmal formation, thromboembolism, and calcification Congestive Heart Failure Congestive heart failure resulting from an isolated persistent duct develops either in infancy or during adult life Infective endarteritis may rarely precipitate heart failure during childhood Heart failure in infancy usually has its onset before the age of 3 months A delayed normal fall in pulmonary vascular resistance may cause the left-to-right flow to increase progressively The clinical picture is initially that of left heart failure, with tachypnea and pulmonary edema Ultimately, signs of right heart failure appear with hepatomegaly Although initially there may be a good response to diuretics, this is seldom maintained and closure is advisable Infants born at term do not respond to indomethacin when older than 3 months The occasional occurrence of sudden death in infants treated medically further encourages a policy of early intervention Among adults, there used to be a group with cardiomegaly and features of left ventricular overload and strain Such patients now are rare in countries with well-developed systems of health care, because it is unlikely their lesion would have escaped detection Congestive heart failure may also occur as a terminal event in patients in whom severe pulmonary vascular disease complicates a persistently patent duct If so, transcatheter closure appears to be the treatment of choice Infective Endarteritis Infective endarteritis in a patient with an uncomplicated persistent duct is uncommon in childhood76 and appears to be prevented by surgery or catheterbased embolization In Sweden, over a 33-year period from 1960, only 2 of 3 million deaths were due to infective endocarditis and a patent arterial duct.79 At Great Ormond Street Hospital from 1984 to 1996, there were only two children with ductal endarteritis out of 17,887 cardiac admissions and at Newcastle-onTyne, from 92,093 cardiac admissions, only one case of infective endocarditis on a duct.80 In the era preceding antibiotics, and interventional or surgical treatment, it was a major cause of death, accounting for almost half of all deaths in several pooled autopsy series.77,78,81 Campbell75 calculated an infection rate of between 0.45 and 1.0% per annum for patients after the first decade The first line of treatment should be with antibiotics, following the recommendations as established by the American Heart Association, with surgery or embolization delayed until sterilization is completed Occasionally, this proves impossible, in which case surgery or occlusion should be performed under continuing antibiotic therapy.82,83 Vegetations are usually found at the pulmonary arterial end of the duct and may give rise to recurrent pulmonary embolization, with the clinical picture suggesting recurrent pneumonia.84 In developing nations with limited access to health care, infective endarteritis associated with the persistently patent duct continues to be a significant health issue.85 Infection may cause some