history

A newborn is typically pronounced healthy and discharged as a well baby. As neonatal pulmonary vascular resistance falls, a left-to-right shunt is established, the ductus murmur emerges, and the diagnosis becomes apparent. Less commonly, a neonate comes to attention because of low birth weight, systemic hypoperfusion, or congestive heart failure without an incriminating ductus murmur (Figure 20-10).^33,42 Absence of a murmur does not necessarily mean that the ductus has closed.¹⁷ A ductus can be patent but silent because of the direction of the jet as it enters the pulmonary artery.⁴³ No correlation has been found between the presence of a murmur and the size of the arterial duct.⁴³ Doppler echocardiography occasionally detects a tiny patent ductus in infants without auscultatory signs of its presence,⁴⁴ or auscultation detects a tiny ductus in adults in whom the diagnosis had been missed (see Figure 20-40). Closure of a patent ductus is occasionally the result of healed infective endocarditis^45,46 or thrombotic occlusion.^47,48

Figure 20-10 Phonocardiograms at the second left intercostal space in a 21-day-old premature male with a nonrestrictive patent ductus arteriosus (see x-ray in Figure 20-8). The low-frequency filter (upper tracing) shows a fourth heart sound (S₄). The high-frequency filter (lower tracing) shows a normal first heart sound (S₁) and an unimpressive early to midsystolic ductal murmur (SM) that fades before a loud single second heart sound (S₂).

Figure 20-40 A, Color Doppler image from a 35-year-old man with patent ductus arteriosus. In the short-axis view, ductal flow is seen entering the pulmonary trunk (PT) toward the right ventricular outflow tract (RVOT). (Ao = aorta; rPA = right pulmonary artery; lPA = left pulmonary artery.) B, Lateral aortogram showing a conical ductus arteriosus (PDA) that was patent at its aortic end (Ao, paired white arrows) but was a virtual thread at its pulmonary arterial end (Video 20-2). (LSA = left subclavian artery.)

In 1561, Vesalius described a valve or membrane in a patent ductus arteriosus.⁴⁹ A valve-like structure was subsequently found in stillborn human fetuses and in newborn rabbits,⁴⁹ and in 1903, a necropsy report called attention to a perforated ductal valve.⁵⁰ Taussig⁵¹ confirmed the presence of a membranous valve at the pulmonary end of a ductus and theorized that rupture might account for the sudden appearance of a ductus murmur, an event occasionally witnessed in children or young adults. A continuous murmur intermittently appeared and disappeared in a patient with a veil-like valve at the pulmonary end of a ductus,⁵² and the abrupt appearance of a loud continuous murmur was described in a 55-year-old man with a ductal membrane.⁵³ Rarely, a closed lumen is reopened by spontaneous intramural dissection of a ductal aneurysm or by propagation of aortic dissection into the ductus.¹⁶

Patent ductus arteriosus predominates in females, with a gender ratio of 2 or 3 to 1.³⁵ Female prevalence is even greater in older patients.⁵⁴ There is a tendency for recurrence of patent ductus in siblings^55–57 and in the offspring of parents with patent ductus.⁵⁵ Familial recurrence has been reported in three generations of a single family.⁵⁸ Identical twins may both have a patent ductus, or the ductus may be patent in only one twin. Canine patent ductus is more common in females and can be hereditary.⁵⁹

In offspring of gravida with maternal rubella, patent ductus arteriosus and pulmonary artery stenosis coexist as congenital malformations (see Chapter 11).^60–62 Maternal rubella resulted in patent ductus arteriosus in one of a twin pair; the other twin had pulmonary artery stenosis. Low birth weight and failure to thrive are features of the rubella syndrome, even if the ductus is restrictive. A seasonal incidence of patent ductus in late winter and early spring coincided with the peak incidence of rubella.⁶²

Persistent patency of the ductus arteriosus is about six times more prevalent in high-altitude locations than in sea-level locations.⁶³ A predilection for increased pulmonary vascular resistance is a feature of high-altitude births with patent ductus.⁶³ The predilection exists even when the ductus is restrictive.⁶³

Congestive heart failure is the most common cause of death directly related to patent ductus.³⁵ Rarely, death is from dissection or rupture of a ductal aneurysm⁶⁴ or from rupture of a hypertensive aneurysmal pulmonary trunk.^65,66 Aneurysm of a nonpatent ductus (see Figure 20-6) can be complicated by rupture, by spontaneous intramural dissection, by systemic embolism, by infection, by recurrent laryngeal nerve paralysis, by compression of the pulmonary trunk, or by hemorrhagic erosion into the esophagus or tracheobronchial tree.^8,9

Infective endarteritis occurs with a restrictive patent ductus because of the high-velocity left-to-right shunt but does not occur with a nonrestrictive ductus and reversed shunt.³⁵ The infection is located at the narrow pulmonary arterial end of the ductus or at the site of an intimal jet lesion in the pulmonary artery opposite the ductus. Susceptibility has not been determined for a tiny clinically silent ductus detected only with Doppler echocardiography (see Figure 20-40; see previous).⁶⁷

Abnormal patterns of cerebral arterial blood flow in infants, especially preterm neonates with a nonrestrictive patent ductus, predispose to central nervous system ischemia and hemorrhage into the germinal matrix.^38,68,69 Increased pulse pressure and major fluctuations of blood flow velocity caused by opening and closing of a ductus may rupture capillaries of the germinal matrix and cause intraventricular hemorrhage. A sharp decrease in diastolic arterial flow velocity can act as a steal from the cerebral circulation.⁶⁸

After the first year of life, most patients with patent ductus arteriosus are asymptomatic. Beginning with the second decade, the risk of infective endarteritis exceeds the risk of congestive heart failure.^35,54,70 In the third decade, more and more patients with a moderately restrictive ductus experience heart failure,^35,54 and those with a restrictive ductus remain asymptomatic. A 20-year-old man with a patent ductus had been a cross-country runner, and an active schoolmistress died at the age of 85 years because of gastrointestinal bleeding. A number of reports have called attention to survival beyond age 60 years (see Figure 20-16)^35,71–75: an elderly woman presented with biventricular failure in her 81st year,⁷⁶ and a patient died at 90 years of age.⁷⁷

Figure 20-16 Tracings from an 84-year-old woman with a moderately restrictive patent ductus arteriosus (see x-ray in Figure 20-38). The murmur in the second left intercostal space (2 LICS) continues through the second heart sound that was timed by the dicrotic notch of the carotid pulse (CAR). The continuous murmur then faded, rendering late diastole murmur-free.

A nonrestrictive patent ductus with Eisenmenger’s syndrome is accompanied by the multisystem systemic disorders of cyanotic congenital heart disease (see Chapter 17).^78,79 Isotonic exercise with an Eisenmenger’s ductus causes leg fatigue without dyspnea because an exercise-induced increase in right-to-left shunt is channeled into the descending aorta (Figures 20-2 and 20-11) distal to the respiratory center and the carotid body, precluding hypoxia-induced stimulation.^78–81 Hypertrophic osteoarthropathy is confined to the lower extremities.^82–84 In an Eisenmenger’s ductus, left ventricular failure is absent because volume overload of the left heart is curtailed. A dilated hypertensive pulmonary trunk may cause hoarseness by compressing the recurrent laryngeal nerve. Angina and syncope are not features of nonrestrictive patent ductus with reserved shunt because right ventricular pressure cannot exceed systemic.⁷⁹ Cyanosis is missed if the feet are not examined (see section Physical Appearance). A young girl came to attention because she noticed that when she sat in a warm bath, her toes were blue but her fingers were pink.

Figure 20-11 A, Photographs of a 28-year-old woman with patent ductus arteriosus, suprasystemic pulmonary vascular resistance, and reversed shunt. The upper photograph shows the patient sitting with her hands placed on the dorsum of her feet. The right hand is acyanotic, and the digits are not clubbed. The left hand is mildly cyanotic, and the thumb is clubbed. The toes are cyanotic and clubbed. In the close-up (lower photograph), the right hand is acyanotic, and the thumb is not clubbed (arrow). The left hand is mildly cyanotic, and the thumb is clubbed (arrow). B, Magnetic resonance image from a 29-year-old woman with a nonrestrictive patent ductus and reversed shunt (curved arrow) from the pulmonary trunk (PT) through a nonrestrictive patent ductus arteriosus (PDA) into the aorta (Ao). (RV/LV = right ventricle/ left ventricle.)

Constriction or closure of the fetal ductus deprives the right ventricle of its only outlet, so neonates present with massive tricuspid regurgitation and right-to-left interatrial shunts.²⁴ Salicylates cause constriction of the fetal ductus, so the history should include enquiries about maternal use of aspirin. Salicylate levels can be determined on umbilical cord blood.⁸⁵

Physical appearance

Maternal rubella is characterized by low birth weight and failure to thrive, irrespective of ductal patency, ductal size, or shunt volume.^86,87 An underdeveloped child with a patent ductus should therefore be examined for cataracts, deafness, and mental retardation (see Figure 20-9).^86,87 Another distinctive phenotype is the clinodactly (overlapping fingers), rocker bottom feet, and lax skin of Trisomy 18 (Figure 20-12).^88,89 Char syndrome is an inherited disorder that maps to chromosome 6p12-p21 and is characterized by ptosis, a flat profile, a very short philtrum, patulous duck-bill lips, facial dysmorphism, and abnormalities of the hands.^90–93 The recurrence rate in offspring of an affected parent is 50%.⁹²

Figure 20-12 A, Photographs of a female infant with patent ductus arteriosus, ventricular septal defect, and the physical appearance of trisomy 18 with lax skin and overlapping fingers (clinodactly). B, Rocker-bottom feet in A are shown.

Differential cyanosis and clubbing are important physical signs of patent ductus with reversed shunt (see Figures 20-2 and 20-11; see previous).^79,94 The toes are cyanosed and clubbed because unsaturated blood is selectively delivered to the lower extremities. A small amount of unsaturated blood often enters the left subclavian artery, so the digits of the left hand, especially the thumb, are mildly cyanosed and clubbed (see Figure 20-11 A). The fingers of the right hand are normal because unsaturated blood does not reach the right subclavian artery. In the rare presence of bilateral patent ductuses with reversed shunt, the right arm is cyanosed because the right subclavian artery receives desaturated blood from the pulmonary artery via the right ductus arteriosus.¹²

Patients who are old enough to follow instructions should be examined sitting or squatting with their hands placed alongside their feet or on the dorsum of their feet to facilitate comparison of fingers and toes (see Figure 20-11A). The right and left thumbs should be compared (see Figure 20-11A). Differential cyanosis is exaggerated by isotonic exercise or by warming the hands and feet, which are maneuvers that increase skin blood flow and exaggerate the color differences. In neonates with persistent fetal circulation, the right-to-left ductal shunt may cause distinctive differential cyanosis confined to the head, right shoulder, and right arm with a demarcation line that runs obliquely from above the left shoulder to below the right axilla.¹⁸

Healthy individuals, especially young women, may have peripheral cyanosis of the feet because of vasoconstriction, a mechanism that is suspected when the feet are cold. Diagnostic error is prevented by warming the extremities, which abolishes peripheral cyanosis but exaggerates central cyanosis.

Arterial pulse

Wide systemic pulse pressure is an important physical sign of patent ductus arteriosus with a large left-to-right shunt.^40,94 This sign is especially useful in symptomatic neonates without a ductus murmur. However, the arterial pulse may be weak in preterm infants in whom systemic flow is reduced by the steal effect associated with aortopulmonary shunting (see previous).^37,38 The typical pulse is characterized by a brisk rise, a single or bisferiens peak, and a rapid collapse (Figure 20-13). Diastolic flow from aortic root into pulmonary trunk lowers the aortic diastolic pressure, and a large left ventricular stroke volume with forceful left ventricular contraction maintains or elevates aortic systolic pressure. The carotid, brachial, femoral, and even dorsalis pedis pulses can be bounding.⁹⁴ The superficial palmar arch as it crosses the heads of the metacarpals is sometimes evident as a visible pulsation. In a child with a large patent ductus, an erythematous wheal caused by a mosquito bite blushed and blanched synchronously with the pulse.⁹⁵

Figure 20-13 Femoral arterial (FA) and central aortic pulses in two patients aged 18 months and 22 months, both with a nonrestrictive patent ductus arteriosus and large left-to-right shunts. Pulse pressures are wide with a brisk rate of rise, a single or bisferiens (twin) peak, and a rapid collapse. A normal brachial arterial pulse in the left panel is shown for comparison.

When pulmonary vascular disease reverses the shunt, the arterial pulse is usually normal. However, in the presence of pulmonary hypertensive pulmonary regurgitation, the aortic diastolic pressure is lowered and the pulse pressure widens because diastolic flow is from the aorta through the ductus into the pulmonary artery, across the incompetent pulmonary valve, and into the right ventricle.

Jugular venous pulse

Congestive heart failure is accompanied by a rise in mean jugular venous pressure with an increase in the A and V waves. When suprasystemic pulmonary vascular resistance reverses the shunt, the A wave is relatively unimpressive because the right ventricle adapts to systemic vascular resistance without augmented right atrial contraction.

Precordial movement and palpation

George A. Gibson⁹⁶ wrote, “When the ductus arteriosus is permanently patent, a very distinct thrill is to be felt—a thrill which distinctly follows the systole of the heart and persists until the diastolic phase has existed for some time.”²

A moderately restrictive patent ductus is accompanied by volume overload of the left ventricle and a dynamic left ventricular impulse. A right ventricular impulse is relatively unimpressive because pressure overload of the right ventricle is only moderate.

A nonrestrictive ductus with low pulmonary vascular resistance results in appreciable volume overload of the left ventricle and systemic systolic pressure in the right ventricle. The left ventricular impulse is hyperdynamic, and the right ventricular impulse is sustained. A dilated pulmonary trunk and a loud pulmonary closure sound are palpable together. If a thrill is present, it is likely to be confined to systole (see section Auscultation). When flow through the ductus is reversed, pulmonary hypertension exists without volume overload of the left ventricle, so palpation detects only a right ventricular impulse. Symptomatic infants with a nonrestrictive patent ductus and low pulmonary vascular resistance have a hyperdynamic volume-overloaded left ventricular impulse accompanied by the conspicuous impulse of a hypertensive failing right ventricle.

Auscultation

In 1900, Gibson⁹⁶ characterized the murmur of patent ductus arteriosus:“It persists through the second sound and dies away gradually during the long pause. The murmur is rough and thrilling. It begins softly and increases in intensity so as to reach its acme just about, or immediately after the incidence of the second sound, and from that point gradually wanes until its termination.”

Gibson’s description cannot be improved on. Although he was not the first to describe the continuous murmur of patent ductus, he precisely characterized the murmur and confidently established the clinical diagnosis based on that characterization.² The classic murmur of uncomplicated patent ductus arteriosus rises to a peak in latter systole; continues without interruption through the second sound, which it envelops; and then declines in intensity during the course of diastole (Figures 20-14, 20-15, and 20-16). The murmur can occupy the entire cardiac cycle (see Figure 20-14), or the end of diastole or early systole can be murmur-free (see Figure 20-15). The term continuous is best applied to the uninterrupted progression of the murmur through the second heart sound and not to the presence of murmur throughout the cardiac cycle.⁹⁴ The ductus murmur is therefore considered continuous even when late diastole and early systole are murmur-free.

Figure 20-14 Simultaneously recorded phonocardiograms from within the pulmonary artery and on the thoracic wall at the second left intercostal space of a 7-year-old girl with a moderately restrictive patent ductus arteriosus and a 2 to 1 left-to-right shunt. In Gibson’s words, the murmur “begins softly and increases in intensity so as to reach its acme just about, or immediately after the incidence of the second heart sound, and from that point gradually wanes until its termination.”⁹⁶

Figure 20-15 Schematic sequential modifications of the murmur of patent ductus from a nonpulmonary hypertensive left-to-right shunt (top) to a pulmonary hypertensive right-to-left shunt (bottom). (MDM = mid-diastolic murmur; EDM = early diastolic murmur; A₂/P₂= aortic and pulmonary components of the second heart sound.)

High-velocity flow through a restrictive ductus generates a relatively soft high-frequency continuous murmur. A moderately restrictive ductus generates a loud coarse machinery murmur punctuated with eddy sounds that are randomly distributed in the second half of systole and in the first half of diastole (Figure 20-17A).^44,94 Intracardiac phonocardiography records the maximal intensity of the ductus murmur in the pulmonary artery at the pulmonary ostium of the ductus (see Figure 20-14). Intraoperative phonocardiograms from the surface of the pulmonary trunk are in accord with this localization,⁹⁷ and these observations coincide with the chest wall position of the ductus murmur, which is loudest in the first or second intercostal space or beneath the left clavicle as Gibson originally stated.²

Figure 20-17 Tracings from an 18-year-old woman with a nonrestrictive patent ductus arteriosus and increased pulmonary vascular resistance, but a 2.3 to 1 left-to-right shunt. A, The ductus murmur in the first left intercostal space (1 LICS) continued (paired arrows) for a short time after the aortic component of the second heart sound (A₂). Eddy sounds (lower arrows) punctuate the murmur. (CAR = carotid pulse.) B, In the fourth left intercostal space (4 LICS), the ductus murmur is holosystolic (SM) and devoid of eddy sounds. The short, low-frequency, mid-diastolic murmur (MDM) at the apex was caused by augmented flow across the mitral valve.

Occasionally, a short large ductus is devoid of murmur despite a substantial left-to-right shunt (Figure 20-18). Ductal murmurs are often absent in infants with a nonrestrictive patent ductus and congestive heart failure (see Figure 20-10) and in a significant number of preterm infants with respiratory distress.⁹⁸ Failure to detect a murmur, a silent but patent ductus, does not necessarily mean that the ductus has closed (see section The History).^17,43,99 A relatively rare auscultatory variation is intermittent disappearance and reappearance of an otherwise typical continuous ductal murmur.^52,100,101 Interruption of flow has been ascribed to acute angulations of an elongated ductus^100,101 or to a valve or veil-like structure within the ductus (see previous).⁵² A similar mechanism has been proposed for the transient diastolic ductal murmur of the neonate.¹⁰² Reappearance of a continuous murmur long after ductal closure has been ascribed to reopening caused by a tear in the valve of the ductus⁵⁰ or to spontaneous intramural dissection.

Figure 20-18 Tracings from a 30-year-old man with an unusually large, short patent ductus. Despite a 2 to 1 left-to-right shunt, a ductus murmur was neither heard nor recorded. (2 LICS = second left intercostal space.) Relatively wide expiratory splitting of the second heart sound was caused by delay in the loud pulmonary component (P₂) that was transmitted to the apex. (S₁ = first heart sound; A₂ = aortic component of the second sound; CAR = carotid pulse.)

The shape, length, and timing of the murmur of patent ductus arteriosus depend on instantaneous differences in pressure and flow between the aorta and pulmonary trunk (see Figure 20-15).^103,104 At the beginning of systole, flow into the pulmonary artery is derived from the right ventricle rather than the ductus. During the course of systole, the flow contribution from the ductus progressively increases, and during diastole, flow into the pulmonary artery is from the ductus alone.^94,105 Systolic reinforcement of the ductus murmur described by Skoda occurs because flow from aorta into pulmonary trunk is greater in systole, especially when the systemic pulse pressure is wide, and because systolic flow from right ventricle into pulmonary artery is reinforced by simultaneous flow from the ductus, whereas diastolic flow is derived from the ductus alone. As pulmonary vascular resistance rises, the pulmonary arterial and aortic diastolic pressures equalize (Figure 20-19) and diastolic ductal flow diminishes and finally vanishes, so the diastolic portion of the continuous murmur disappears, leaving a holosystolic murmur (Figures 20-15, 20-20, and 20-21). With a further increase in pulmonary vascular resistance, the systolic portion of the ductus murmur shortens (see Figures 20-15 and 20-21) and ultimately disappears altogether (see Figure 20-15). The ductus is then silent because right-to-left ductal flow, a reversed shunt, does not generate a murmur.¹⁰⁵ The classic Gibson murmur is then replaced by auscultatory signs of pulmonary hypertension: namely, a short pulmonary midsystolic murmur introduced by an ejection sound, a single or closely split second heart sound, a loud pulmonary component, and the Graham Steell murmur of hypertensive pulmonary regurgitation (Figures 20-15 and 20-22).¹⁰⁵ The diagnosis of patent ductus arteriosus cannot be based on auscultatory signs but can confidently be based on differential cyanosis (see Figure 20-11; see section Physical Appearance).

Figure 20-19 Tracings from a 15-year-old boy with a nonrestrictive patent ductus arteriosus and increased pulmonary vascular resistance, but a 2 to 1 left-to-right shunt. A, The ductus murmur in the first left intercostal space (ICS) continued through the timing of the second heart sound (paired arrows) but faded well before the subsequent first heart sound (S₁). B, An identical murmur was recorded within the pulmonary artery (IN PA) at its bifurcation. The brachial arterial (BA) and pulmonary arterial (PA) pulses diverge in systole but converge in diastole (center panel), so the ductus murmur is maximal in systole and minimal in diastole (left panel). The right panel shows relatively low diastolic pressures in the brachial artery and in the aorta with a bisferiens (twin-peaked) pulse in the central aorta.

Figure 20-20 Phonocardiograms from an 11-year-old girl with a nonrestrictive patent ductus arteriosus and increased pulmonary vascular resistance, but a 2 to 1 left-to-right shunt. The upper left panel shows a holosystolic ductal murmur (SM) in the second left intercostal space (2 LICS). A louder holosystolic ductal murmur was recorded from within the pulmonary artery at its bifurcation (Bifur. PA). The remaining panels show the intracardiac the murmur fading then vanishing as the catheter tip microphone was withdrawn from the bifurcation of the pulmonary artery to the main pulmonary artery and into right ventricle (RV).

Figure 20-21 Tracings from a 3-year-old girl with a nonrestrictive patent ductus and increased pulmonary vascular resistance but a 2.7 to 1 left-to-right shunt. The intracardiac microphone recorded a decrescendo holosystolic murmur within the lumen of the patent ductus arteriosus (PDA). The right ventricle (RV) was silent except for the pulmonary component of the second heart sound (P₂). The femoral arterial (FA) and pulmonary arterial (PA) pulses diverge in systole but are identical in diastole, so the ductus murmur was confined to systole.

Figure 20-22 Phonocardiogram from the second left intercostal space of a 26-year-old woman with a nonrestrictive patent ductus, suprasystemic pulmonary vascular resistance, and reversed shunt. A midsystolic murmur (SM) originated in the dilated hypertensive pulmonary trunk. A Graham Steell murmur (EDM) issued from a loud delayed pulmonary component of the second heart sound (P₂). (S₁ = first heart sound; A₂ = aortic component of the second sound.)

In the newborn, a transient soft crescendo systolic murmur from left-to-right flow through the ductus is sometimes detected before normal physiologic closure.^106–108 The murmur ends with the second sound or continues just beyond it.¹⁰⁶ These harmless transient neonatal murmurs are physiologically analogous to the not so harmless murmurs that appear when patent ductus arteriosus is subsequently accompanied by a rise in pulmonary vascular resistance. Even when a ductus is destined to remain patent, the neonatal ductal murmur is initially systolic and becomes continuous only after pulmonary vascular resistance has fallen sufficiently to permit both systolic and diastolic ductal flow.

When the left-to-right shunt is large, apical mid-diastolic murmurs are generated by increased flow across the mitral valve.¹⁰⁵ These murmurs cannot not heard unless the diastolic portion of the continuous murmur is attenuated by an increase in pulmonary vascular resistance (Figures 20-15, 20-17, and 20-23).¹⁰⁵ In patent ductus arteriosus with reversed shunt, a mid-diastolic murmur has been attributed to a right-sided Austin Flint mechanism associated with pulmonary regurgitation.¹⁰⁹ To-and-fro murmurs over the cranium of infants with a nonrestrictive patent ductus arteriosus have been ascribed to accelerated forward flow followed by rapid diastolic runoff.

Figure 20-23 Phonocardiogram at the apex of a 5-year-old girl with a nonrestrictive patent ductus and a 3 to 1 left-to-right shunt. The systolic portion of the ductus murmur (SM) was transmitted to the apex where a prominent middiastolic murmur (DM) was caused by augmented flow across the mitral valve.

The second heart sound is occasionally paradoxically split when the left-to-right shunt is large.¹¹⁰ Prolonged left ventricular ejection and short right ventricular ejection are held responsible.^40,110 A loud continuous murmur punctuated by eddy sounds obscures the second heart sound. An increase in pulmonary vascular resistance renders the second sound audible because the diastolic portion of the continuous murmur softens or disappears (see Figures 20-15, 20-17, and 20-19). When the shunt is reversed, the second sound is single or closely split, and the pulmonary component is loud (see Figure 20-15). The second sound is widely split when depressed right ventricular contractility and prolonged right ventricular ejection delay the pulmonary component (see Figures 20-22 and 20-23).

Electrocardiogram

A moderately restrictive patent ductus arteriosus with increased pulmonary blood flow is accompanied by a prolonged bifid left atrial P wave in one or more limb leads and in right precordial leads (Figures 20-24 and 20-25). The PR interval is prolonged in 10% to 20% of cases (see Figure 20-24).¹¹¹ Atrial fibrillation occurs in older patients. The QRS axis is usually normal, but an occasional infant has right axis deviation, especially neonates with respiratory distress. Rare examples of left axis deviation have been reported.¹¹² The rubella syndrome may be associated with an unusually superior QRS axis directed upward and either to the left or right.¹¹³

Figure 20-24 Electrocardiogram from a 37-year-old woman with a moderately restrictive patent ductus arteriosus, a 2.8 to 1 left-to-right shunt, and a pulmonary arterial pressure of 48/18 mm Hg (see x-ray in Figure 20-32). There is a broad bifid left atrial P wave in lead 2. The PR interval is 200 msec. The QRS is prolonged, and the axis is horizontal. Left ventricular volume overload is manifested by prominent q waves in leads aVL and V₆ and by tall R waves and ST-T wave changes in lead aVL and in leads V_4-6.

Figure 20-25 Electrocardiogram from a 19-month-old male with a moderately restrictive patent ductus, a 3 to 1 left-to-right shunt, and a pulmonary arterial pressure of 45/22 mm Hg (see x-ray in Figure 20-31). There are biphasic left atrial P waves in leads V_1-2. Because the QRS axis is normal, the tall R waves of left ventricular volume overload appear in leads 2 and aVF. Volume overload of the left ventricle is also manifested by tall R waves and upright T waves in leads V_5-6. Right ventricular hypertrophy is manifested by prominent S waves in leads V_5-6 and a prominent R wave in lead V₁. Leads V_2-3 are half standardized and exhibit large RS complexes of biventricular hypertrophy.

A nonrestrictive patent ductus with low pulmonary vascular resistance is associated with biatrial P waves and combined ventricular hypertrophy. Large equidiphasic RS complexes appear in most if not all precordial leads, with tall R waves and prominent S waves in leads V_5-6 (Figures 20-25 and 20-26). Volume overload of the left ventricle is responsible for tall R waves, prominent q waves, and tall peaked T waves in leads V_5-6 (see Figures 20-25 and 20-26).

Figure 20-26 Electrocardiogram from a 16-year-old boy with a moderately restrictive patent ductus, pulmonary arterial pressure of 80/50 mm Hg, and a 2 to 1 left-to- right shunt. The QRS axis is normal and depolarization is clockwise, so prominent q waves and tall R waves of left ventricular volume overload appear in leads 2, 3, and aVF. Volume overload of the left ventricle is also manifested by the deep S wave in lead V₁ and by prominent q waves, tall R waves, and peaked upright T waves in leads V_5-6. Biventricular hypertrophy is reflected in the large RS complexes in leads V_2-4, which are half standardized.

Patent ductus with pulmonary vascular disease and reversed shunt is accompanied by peaked right atrial P waves in leads 2, 3, and V₁ (Figure 20-27). Right ventricular hypertrophy is manifested by right axis deviation, tall R waves in lead V₁, and inverted right precordial T waves and is prominent in left precordial leads S waves (see Figure 20-27). R waves in leads V_5-6 imply that a left-to-right shunt previously existed (see Figure 20-27).

Figure 20-27 Electrocardiogram from a 28-year-old woman with a non-restrictive patent ductus, suprasystemic pulmonary vascular resistance, and reversed shunt. Peaked right atrial P waves are present in lead 2 and leads V_1-2. Isolated right ventricular hypertrophy is manifested by right axis deviation, tall monophasic R waves, and inverted T waves in leads V_1-4 and prominent S waves in left precordial leads.

X-ray

The ductus itself is occasionally seen in the frontal projection as an inconspicuous soft convexity between the aortic knob and the pulmonary artery segment (Figures 20-5A and 20-28).¹¹⁴ A striking exaggeration of this inconspicuous shadow is an aneurysm of a nonpatent ductus (see Figure 20-6). Calcium appears in the ductus of older patients (Figure 20-29; see Figure 20-38A).¹¹⁵

Figure 20-28 A, Close-up of a portion of the chest x-ray in the 14-year-old girl whose aortogram is shown in Figure 20-3. The soft convex shadow of the patent ductus (arrow) is located between the aortic knuckle (AO) and pulmonary trunk (PT). The convex shadow represents the dilated aortic end of the conical ductus shown in the aortogram of Figure 20-3. B, Aortogram in a 5-year-old girl. The convex shadow of a conical ductus (arrow) located between the aortic knuckle (AO) and the pulmonary trunk (PT). Compare with Figure 20-5.

Figure 20-29 X-ray from a 63-year-old woman with a restrictive patent ductus and a left-to- right shunt of 1.3 to 1. A, Ductal calcification is the comma-like density between the aortic knuckle and the main pulmonary artery segment. B, Close-up of the ductal calcification (arrow). The x-ray was otherwise normal.

Figure 20-38 A, X-ray from the 84-year-old woman with a moderately restrictive patent ductus arteriosus (PDA) whose phonocardiogram is shown in Figure 20-16. The pulmonary trunk (PT) and its right branch are dilated. A thin rim of calcium appears in the transverse aorta (Ao). An enlarged left ventricle (LV) occupies the apex, and an enlarged right atrium occupies the lower right cardiac border. B, Notch view of ductal flow going from aorta (Ao) to pulmonary trunk (PT) (Video 20-1). (LPA = left pulmonary artery.)

A moderately restrictive patent ductus with low pulmonary vascular resistance results in increased pulmonary arterial vascularity, enlargement of the pulmonary trunk and its proximal branches, and enlargement of the left atrium and left ventricle (Figures 20-30, 20-31 and 20-32).¹¹⁴ Asymmetric pulmonary vascularity is occasionally represented by a hyperlucent left lung.¹¹⁶ In infants, the ascending aorta is inconspicuous because intrauterine ductal flow does not traverse the aorta (see Figures 20-5 and 20-30). After birth, left-to-right ductal flow recirculates through the aortic root, so the ascending aorta becomes prominent (see Figure 20-3).¹¹⁷ In infants and children with a nonrestrictive patent ductus and low pulmonary vascular resistance, pulmonary arterial vascularity is markedly increased and all four cardiac chambers are enlarged (Figure 20-33).

Figure 20-30 X-rays from a 13-month-old female with a moderately restrictive patent ductus arteriosus, pulmonary arterial pressure of 39/15 mm Hg, and a 2.3 to 1 left-to-right shunt. A, Pulmonary vascularity is increased and the pulmonary trunk (PT) and its right branch (white arrow) are prominent, but the ascending aorta is inconspicuous. The left cardiac border formed by a dilated left ventricle (vertical black arrow) and the right cardiac border is formed by a dilated right atrium (horizontal black arrow). B, The femoral artery catheter passed through the ductus (first acute bend, horizontal arrow), into the pulmonary trunk, across the pulmonary valve into the right ventricle (right vertical arrow), and finally across the tricuspid valve into the right atrium where the tip lies (left vertical arrow).

Figure 20-31 X-rays from a 19-month-old male with a nonrestrictive patent ductus and a 3 to 1 left-to-right shunt. The electrocardiogram is shown in Figure 20-25. A, The increased pulmonary vascularity is both arterial and venous. The pulmonary trunk (PT) and its right branch (arrow) are dilated. The apex is formed by an enlarged left ventricle (LV), and the right cardiac border is formed by a dilated right atrium (RA). B, The lateral barium esophagram outlines a moderately enlarged left atrium (LA).

Figure 20-32 A, X-rays from a 37-year-old woman with a moderately restrictive patent ductus and a 2.8 to 1 left-to-right shunt. The electrocardiogram is shown in Figure 20-24. Pulmonary vascularity is increased, the pulmonary trunk (PT) is prominent, the apex is occupied by a dilated convex left ventricle (LV), and the right cardiac border is formed by a dilated right atrium (RA). B, Lateral barium esophagram outlines an enlarged left atrium.

Figure 20-33 A, X-ray from a 3-year-old boy with a nonrestrictive patent ductus, low pulmonary vascular resistance, and a 3 to 1 left-to-right shunt (see Figure 20-5 for angiocardiograms). Pulmonary blood flow is increased, the pulmonary trunk (PT) is dilated, an enlarged left ventricle (LV) occupies the apex, and an enlarged right atrium (RA) forms the right cardiac border. B, The right pulmonary artery (RPA) and left pulmonary artery (LPA) are visualized through the patent ductus after contrast material was injected into the balloon-occluded descending aorta (Ao). The intrapulmonary arteries are strikingly enlarged. Compare with the increased pulmonary vascularity in A.

The x-ray of a nonrestrictive patent ductus with reversed shunt exhibits reduced pulmonary vascularity, dilation of the pulmonary trunk and its proximal branches, a normal or near normal left ventricle and left atrium, and an hypertrophied but not significantly dilated right ventricle (Figure 20-34).

Figure 20-34 X-rays from a 14-year-old boy with a nonrestrictive patent ductus, suprasystemic pulmonary vascular resistance, and reversed shunt. A, Pulmonary vascularity is decreased, the pulmonary trunk (PT) and its proximal branches are enlarged, the right atrium (RA) is prominent, and the hypertrophied right ventricle (RV) forms an acute angle with the left hemidiaphragm. B, A catheter from the left median basilic vein entered the pulmonary trunk (PT), crossed the ductus, and came to rest in the descending aorta (DAo). The course of the catheter represents the pathway taken by unoxygenated blood through a reversed ductal shunt (see Figure 20-2,lower, and Figure 20-11A).

Echocardiogram

Echocardiography with color flow imaging and Doppler interrogation establishes the size of the patent ductus (Figure 20-35), the flow dynamics through the ductus, and the physiologic consequences of persistent ductal patency.^103,104,118 Transesophageal echocardiography improves diagnostic accuracy.¹¹⁹ When the shunt is entirely left-to-right, the flow disturbance within the ductus is continuous, with the peak velocity reinforced in latter systole as forward flow from the right ventricle coincides with shunt flow through the ductus (Figure 20-36).^103,104 Systolic forward flow in the aorta distal to the orifice of the ductus is followed by reversed diastolic flow (Figure 20-37). In the presence of large ductal flow, the velocities across the aortic isthmus and in the descending aorta are substantially increased.¹²⁰ The color flow pattern in the pulmonary trunk consists of a ductal jet that adheres the lateral wall, travels toward the pulmonary valve, and then reverses itself to travel up the medial wall (Figure 20-38 and Video 20-1). Alternatively, a jet directed toward the pulmonary valve adheres to the medial wall of the pulmonary trunk (Figure 20-39).

Figure 20-35 Echocardiogram of a moderately restrictive patent ductus (three arrowheads) in a 2-month-old infant. (Ao = aortic valve; PT = pulmonary trunk; DA = descending aorta; RA/LA = right atrium and left atrium.)

Figure 20-36 Continuous-wave Doppler scan from a 7-month-old female with a moderately restrictive patent ductus.

Figure 20-37 Pulsed Doppler scan from a 6-month-old female with a moderately restrictive patent ductus and a 2.8 to 1 left-to-right shunt. Sample volume in the descending aorta distal to the ductus recorded systolic flow (Syst.) down the aorta and diastolic flow (Diast.) in the opposite direction.

Figure 20-39 Color Doppler flow in a 64-year-old man with a restrictive patent ductus. Ductal flow tracts along the medial wall of the pulmonary trunk (PT) and downward toward the pulmonary valve. (rPA = right pulmonary artery; lPA = left pulmonary artery; RVOT = right ventricular outflow tract; Ao = aorta.)

Color flow imaging with Doppler interrogation identifies a clinically silent nonrestrictive patent ductus in premature infants^33,42 and detects the tiny clinically silent ductus in adults (Figure 20-40 and Video 20-2).⁶⁷ In utero ductal closure can be recognized with fetal echocardiography.^121,122 The reversed shunt in a nonrestrictive patent ductus with suprasystemic pulmonary vascular resistance can be identified with Doppler interrogation¹⁰³ and contrast echocardiography.¹²³ Right ventricular systolic pressure and pulmonary arterial diastolic pressure are estimated with continuous-wave Doppler interrogation of the jets of tricuspid and pulmonary regurgitation and with Doppler velocities across the ductus.

Summary

Clinical suspicion of patent ductus arteriosus is heightened by premature birth, maternal rubella, or birth at high altitude. In most patients with a moderately restrictive patent ductus, the clinical signs are unmistakable. The arterial pulse is brisk, the pulse pressure is wide, the left ventricular impulse is dynamic, and auscultation detects the distinctive continuous Gibson murmur that peaks around the second heart sound and is punctuated by eddy sounds. The electrocardiogram reflects volume overload of the left ventricle, and the x-ray shows increased pulmonary arterial vascularity with enlargement of the left ventricle, left atrium, ascending aorta, and pulmonary trunk. Echocardiography with color flow imaging and Doppler interrogation establishes the size of the ductus and the flow dynamics within the ductus and within the contiguous aorta and pulmonary trunk and establishes the hemodynamic consequences of ductal patency.

In infants, a nonrestrictive patent ductus with low pulmonary vascular resistance presents with congestive heart failure. An incriminating ductus murmur is often absent, but the arterial pulses are bounding and the left and right ventricular impulses are hyperdynamic. Echocardiography establishes the diagnosis.

In a nonrestrictive patent ductus with suprasystemic pulmonary vascular resistance and reversed shunt, the ductus murmur is absent, but the diagnosis is confidently made based on distinctive differential cyanosis. The toes are cyanosed and clubbed, but the fingers are spared. The clinical signs are those of pure pulmonary hypertension. The electrocardiogram shows right ventricular hypertrophy with little or no volume overload of the left ventricle. The x-ray exhibits normal or reduced pulmonary vascularity, dilation of the pulmonary trunk, and an unimpressive cardiac silhouette. Echocardiography with color flow and contrast imaging confirms the diagnosis.

Aortopulmonary window

In a lecture delivered in 1830 at the St Thomas Hospital, London, Professor John Elliotson¹²⁴ described the first known case of aortopulmonary window, often called aortopulmonary or aorticopulmonary septal defect. This uncommon malformation consists of a communication, usually nonrestrictive, between adjacent walls of the ascending aorta and pulmonary trunk. During early embryogenesis, two opposing proximal truncal cushions rapidly enlarge and fuse to form the truncal septum that partitions the truncus arteriosus into aortic and pulmonary channels.^125–127 The distal truncoaortic sac is then divided by the aortopulmonary septum. Maldevelopment of the truncal and aortopulmonary septum results in three morphologic types of aortopulmonary window, namely¹²⁵: (1) nonfusion of the embryonic aortopulmonary septum and the truncal septum that results in a moderate-sized circular defect located about midway between the great arterial valves and the bifurcation of the pulmonary trunk; (2) malalignment of the embryonic aortopulmonary septum and truncal septum that results in a defect similarly located but helical-shaped; and (3) complete absence of the embryonic aortopulmonary septum that results in a nonrestrictive defect. The morphogenesis of an aortopulmonary window is unrelated to the morphogenesis of a patent ductus arteriosus, but the physiologic consequences and clinical manifestations of the two malformations are similar if not identical,^128,129 so inclusion in this chapter is appropriate.

Because an aortopulmonary window tends to be nonrestrictive, it is often mistaken for a nonrestrictive patent ductus, which is the most frequent coexisting anomaly, estimated to have an incidence rate of 12% (Figure 20-41).¹²⁹ When pulmonary vascular resistance is suprasystemic and the shunt is reversed, the clinical picture is indistinguishable from a nonrestrictive ventricular septal defect with Eisenmenger’s syndrome (see Chapter 17).⁷⁹ An aortopulmonary window and a ventricular septal defect can coexist, albeit rarely.¹³⁰

Figure 20-41 A, X-ray from a 51-year-old cyanotic woman with an aortopulmonary window, suprasystemic pulmonary vascular resistance, and a reversed shunt. Pulmonary vascularity is normal. The pulmonary trunk (PT) and its proximal branches are moderately enlarged, but the cardiac size and configuration are virtually normal. B, X-ray 5 years later after the advent of atrial fibrillation. The right ventricle (RV) and right atrium (RA) are markedly enlarged. The rim of calcium (Ca) above the dilated pulmonary trunk (PT) proved to be in a restrictive patent ductus. The unmarked arrowhead adjacent to the pulmonary trunk identifies the cross section of a dilated intrapulmonary artery. The patient died in her 58th year.

Aortopulmonary window is somewhat more frequent in males in contrast to patent ductus.¹²⁸ Also in contrast to patent ductus is the rarity of infective endocarditis.¹²⁸ An appreciable percentage of infants with a nonrestrictive aortopulmonary window die of congestive heart failure in infancy or early childhood.¹²⁸ Only a minority reach teenage or young adulthood, but occasional survivals have been reported in the fourth or fifth decade.^128,131 Survival improves when the shunt is limited by a restrictive defect or curtailed by a rise in pulmonary vascular resistance. The patient referred to in Figure 20-41 lived to age 58 years with a nonrestrictive aortopulmonary window and Eisenmenger’s syndrome.

A bounding arterial pulse and a wide pulse pressure are analogous to nonrestrictive patent ductus with low pulmonary vascular resistance (Figure 20-42). When an aortopulmonary window is accompanied by suprasystemic pulmonary vascular resistance and a reversed shunt, unoxygenated blood enters the ascending aorta so differential cyanosis does not occur. The clinical picture is then indistinguishable from nonrestrictive ventricular septal defect with Eisenmenger’s syndrome (see Chapter 17).

Figure 20-42 Tracings from a 2-year-old boy with an aortopulmonary window and a 3.4 to 1 left-to-right shunt. The phonocardiogram in the second left intercostal space (2 LICS) shows a decrescendo holosystolic murmur (SM) punctuated by eddy sounds (paired arrows). The single second heart sound is loud because the pulmonary component (P₂) was increased. The femoral arterial (FA) and pulmonary arterial (PA) pressure pulses diverge in systole but are identical in diastole, so the murmur is confined to systole. (S₁ = first heart sound; A₂ = aortic component of the second sound.)

A moderately restrictive aortopulmonary window generates a continuous murmur indistinguishable from a moderately restrictive patent ductus arteriosus.^128,132 The physiologic mechanisms responsible for variations in the murmur of a nonrestrictive aortopulmonary window are analogous to those that apply to a nonrestrictive patent ductus arteriosus (see Figure 20-15). In 80% of patients, the murmur is systolic rather than continuous (seeFigure 20-42)¹²⁸ and is punctuated by eddy sounds (see Figure 20-42). When the murmur is continuous, its diastolic portion is likely to be shortened (Figure 20-43). A nonrestrictive aortopulmonary window with suprasystemic pulmonary vascular resistance and reversed shunt is accompanied by auscultatory signs of pulmonary hypertension. No murmur is generated across the defect. A Graham Steell murmur may appear before the shunt is reversed because of dilation of the hypertensive pulmonary trunk.

Figure 20-43 Phonocardiograms from a 14-year-old boy with an aortopulmonary window and a 3 to 1 left-to-right shunt. The systolic murmur (SM) in the second left intercostal space (2 LICS) continues just beyond the second heart sound (S₂; see paired arrows). (E = pulmonary ejection sound.) At the apex, a soft third heart sound (S₃) and a mid-diastolic murmur (DM) were the result of increased flow across the mitral valve. There was a faint mitral opening sound (OS).

Systolic or continuous murmurs generated by an aortopulmonary window are typically maximal in the third left intercostal space.¹³¹ A prominent systolic murmur at the mid to lower left sternal border invites the mistaken diagnosis of ventricular septal defect, but eddy sounds and a bounding arterial pulse should prevent error (see Figure 20-42). Apical mid-diastolic murmurs represent increased flow across the mitral valve (see Figure 20-43).

The electrocardiogram of a nonrestrictive aortopulmonary window with low pulmonary vascular resistance reflects combined ventricular hypertrophy in response to volume overload of the left ventricle and pressure overload of the right ventricle, analogous to a nonrestrictive patent ductus with low pulmonary vascular resistance (see Figure 20-25). When pulmonary vascular resistance is suprasystemic and the shunt is reversed, the electrocardiogram is analogous to nonrestrictive patent ductus with Eisenmenger’s syndrome (see Figure 20-27).

The x-ray cannot distinguish a nonrestrictive aortopulmonary window with low pulmonary vascular resistance from a nonrestrictive patent ductus with large left-to-right shunt (Figures 20-44 and 20-45). When the shunt is reversed (see Figure 20-41), the x-ray resembles a nonrestrictive patent ductus with Eisenmenger’s syndrome (seeFigure 20-34).

Figure 20-44 X-rays from a 5-month-old female with an aortopulmonary window and a 3.5 to 1 left-to-right shunt. A, Pulmonary vascularity is increased, pulmonary venous congestion is evident at the right hilus (arrow), the pulmonary trunk (PT) is prominent, and a dilated left ventricle (LV) occupies the apex. B, Lateral view shows an enlarged left atrium (LA).

Figure 20-45 X-rays from a 6-month-old male with an aortopulmonary window and a 3.5 to 1 left-to-right shunt. A, Pulmonary arterial and pulmonary venous vascularity are markedly increased. A dilated left ventricle (LV) occupies the apex. The course of the femoral venous catheter is into the right atrium (lower left arrow), across the right ventricular outflow tract into the pulmonary trunk (PT), through the aortopulmonary window into the ascending aorta (smaller oblique arrow), and into the right subclavian artery. B, The lateral projection shows the catheter passing from the pulmonary trunk (curved arrow) across the aortopulmonary window into the aorta and into the right subclavian artery (upper arrow).

Echocardiography localizes the aortopulmonary window between the ascending aorta and pulmonary trunk just proximal to the bifurcation (Figure 20-46 and Video 20-3)^129,133,134 and determines whether a patent ductus coexists. Color flow imaging identifies the shunt as left-to-right, right-to-left (Figure 20-47 and Video 20-3), or bidirectional.

Figure 20-46 Echocardiogram (parasternal short-axis) from a 5-month-old female with an aortopulmonary window (arrow) between the ascending aorta (Ao) and the pulmonary trunk (PT) (Video 20-3). (rp = right pulmonary artery.)

Figure 20-47 A, Echocardiogram (parasternal long-axis) from the 51-year-old patient whose x-rays are shown in Figure 20-41. Paired arrows identify the aortopulmonary window (APW). (Ao = aorta; AV = aortic valve; LA = left atrium.) B, Black-and-white print of a parasternal long-axis color flow image. Large white arrowheads bracket a right-to-left shunt (black arrow) through the aortopulmonary window (Video 20-3).

Summary

Aortopulmonary window is an uncommon malformation that should be considered in acyanotic patients with clinical evidence of a nonrestrictive patent ductus and a large left-to-right shunt. The murmur is usually systolic rather than continuous and is maximal in the third left intercostal space. The relatively low location of the murmur arouses suspicion of ventricular septal defect, but eddy sounds and a bounding arterial pulse should prevent this error. A moderately restrictive aortopulmonary window is accompanied by a continuous murmur and clinical signs indistinguishable from a moderately restrictive patent ductus except for the relatively low precordial location of the murmur. An aortopulmonary window with suprasystemic pulmonary vascular resistance and reversed shunt is clinically indistinguishable from a nonrestrictive ventricular septal defect with Eisenmenger’s syndrome. Echocardiography with color flow imaging and Doppler interrogation make the distinction.