Andersons pediatric cardiology 1113

pulmonary valve stenosis is supported by a study by Romeih and colleagues, who reported a significantly increased stroke volume and cardiac output during cardiopulmonary exercise and dobutamine stress testing in 11 adults with untreated mild to moderate pulmonary valve stenosis.22 This is different from patients who were treated late for severe pulmonary valve stenosis, in whom there may be a persistent impairment in the ability to increase right ventricular stroke volume.22 In patients with more severe pulmonary stenosis, the onset of symptoms may still be delayed into late childhood or early adult life In a small proportion of patients with pulmonary stenosis and an atrial communication, central cyanosis can be present, especially with exercise This is a late physical sign because the atrial-level right-to-left shunting depends on the diastolic properties of the right ventricle With severe right ventricular hypertrophy and poor right ventricular diastolic compliance, the passage of unoxygenated blood across an interatrial communication into the left atrium is facilitated In addition to central cyanosis in the presence of a right-to-left shunt across an intraatrial communication, patients with moderate to severe pulmonary stenosis may also develop peripheral cyanosis during exercise, in particular with an intact atrial septum This is related to a limitation of the right ventricle to increase its stroke volume and cardiac output, resulting in an increased peripheral tissue oxygen extraction Reported symptoms include exercise intolerance and dyspnea Chest pain of an ischemic nature―possibly due to subendocardial ischemia of the right ventricle, syncope, and severe dyspnea on minimal exertion―is a late finding and should prompt rapid intervention Physical Examination The physical examination findings are summarized in Table 42.1 Depending on the degree of stenosis, there may be a thrill at the second left intercostal space This is not felt over the carotid arteries, thus differentiating the cause of the thrill from aortic stenosis Palpating for a thrill in the suprasternal notch should be avoided, since thrills here can be due to either aortic or pulmonary stenosis Table 42.1 Physical Signs That Can Be Elicited in Valvar Pulmonary Stenosis Severity of Pulmonary Stenosis Physical Sign Cyanosis Jugular venous pulse Precordial thrill Right ventricular heave Systolic ejection click Ejection systolic murmur Second heart sound Mild Absent Normal Absent Absent Present Midsystolic, ejection Normal Moderate Absent Normal Probable Probable Expiratory Long ejection systolic Wide, variable Severe Possible, if interatrial septal defect Possibly elevated, prominent a-wave Pronounced Pronounced Probably absent Long, ejection systolic, past aortic closure sound Absent pulmonary closure sound Widened splitting of the second heart sound and an ejection systolic murmur is maximally heard here, with radiation into the back The delayed closure of the valvar leaflets causes the widened splitting This is not due to electrical prolongation of systole but rather to continued flow through the pulmonary valve even after right ventricular pressures have fallen to levels that would usually have resulted in valvar closure This is likely to be a ventriculoarterial interaction, favored by normal or increased impedance of the pulmonary vascular bed It can be termed “pulmonary hangout.” The more severe the degree of stenosis, the wider the splitting of the second heart sound As the severity of pulmonary valve stenosis progresses, the mobility of the valvar leaflets is often reduced, thereby also leading to a reduced intensity of P2 Furthermore, the ejection systolic murmur may continue beyond the aortic component of the second heart sound, making it more difficult to appreciate A2 Hence the finding of a single second heart sound is common in patients with more severe pulmonary valve stenosis In most cases of valvar pulmonary stenosis, a systolic ejection click precedes the onset of the systolic murmur The click is usually heard loudest separate from the area of maximal intensity of the cardiac murmur, nearer the apex, or at the left lower sternal edge The systolic ejection click originates from the rapid deceleration of the pulmonary valvar mechanism, as the fusion along their zones of apposition prevents the valvar leaflets from reaching their intended positions against the walls of the valvar sinuses Presence of the click also depends on the timing of opening of the pulmonary valve In mild disease, without right ventricular hypertrophy, the pulmonary valve opens in ventricular systole with the emission of an ejection click In severe disease, with right ventricular hypertrophy and impaired diastolic compliance, the valve opens in atrial systole, without the rapid deceleration caused by ventricular systole Thus no click is heard In moderate pulmonary stenosis, inspiration augments systemic venous flow and atrial filling The augmented atrial pressure allows atrial systole to open the pulmonary valve Hence the systolic ejection click is heard only in expiration In some patients with pulmonary stenosis and tricuspid regurgitation, the right ventricular pressure is high enough to cause a pansystolic murmur at the left lower sternal edge, related more to the degree of tricuspid regurgitation than to the valvar stenosis itself The physical findings in patients with supravalvar stenosis are similar except for the absence of the ejection click Stenosis further out into the pulmonary arterial tree can be heard as long systolic or continuous murmurs in the axillae or over the lung fields at the back Careful general phenotypic assessment may show the signs or syndromic diagnosis, as seen in Noonan, Alagille, or Williams syndrome Basic Investigations Basic investigations are directed toward assessing the effects and severity of the pulmonary stenosis Electrocardiogram The most pertinent electrocardiographic (ECG) findings are summarized in Table 42.2 ECG may be normal, it may reveal the degree of right ventricular hypertrophy, or, indeed, it may point to right atrial enlargement, which will be seen only in the more severe cases There are no features of the ECG that are unique to valvar pulmonary stenosis, although the severity of stenosis is reflected in the degree of right ventricular hypertrophy and strain A full right bundle-branch-block pattern is rare, but an RSR′ pattern can be seen and reflects a lesser degree of right ventricular hypertrophy than the equivalent exclusive Rwave complex in V1.23,24 Table 42.2 Severity of Pulmonary Stenosis Electrical axis R:S ratio V1 R amplitude Right atrial enlargement Mild Normal Normal Normal Normal Moderate 90–130 up to 4 : 1 in V1 10–20 mV Possible Severe 110–150 Also inverted in left leads >28 mV Present The use of ECG findings to estimate the severity of pulmonary valve stenosis