The ductus arteriosus is a normal fetal blood vessel that connects the pulmonary artery to the aorta. It typically closes shortly after birth as pulmonary vascular resistance decreases. A patent ductus arteriosus (PDA) is the failure of the ductus arteriosus to close, allowing blood to shunt from the aorta to the pulmonary artery. PDAs are diagnosed based on history, physical exam findings like a continuous murmur, and imaging like echocardiography. Treatment involves medical closure with drugs or percutaneous device closure for larger PDAs.
2. History In 1593 GiambattistaCarcano described ductusarteriosus in book “great cardiac vessels of the fetus” Leo bottani falsely associated with “ ductus”
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4. Anatomy Normal fetal vascular channel between aorta and pulmonary artery. The pulmonary end is located to left of bifurcation of pulmonary trunk Aortic end is just beyond the origin of left subclavian artery With a right aortic arch, the ductusarteriosus may be on the right, joining the right pulmonary artery and the right aortic arch just distal to the right subclavian artery
7. microscopic structure of the ductusarteriosus differs the media of the ductusarteriosus consist largely of layers of smooth muscle arranged spirally in both leftward and rightward directions The intimal layer of the ductusarteriosus is thicker than that of the adjoining arteries and contains an increased amount of mucoid substance
9. Physiology Role in the Fetus 6 weeks of gestation, the ductusarteriosus is developed sufficiently to carry most of the right ventricular output The right ventricle ejects about two thirds of combined ventricular output ductusarteriosus permits flow to be diverted away from the high-resistance pulmonary circulation
10. Normal Postnatal Closure closure of the ductusarteriosus is effected in two phases Immediately after birth, contraction and cellular migration of the medial smooth muscle in the wall of the ductus resulting in functional closure commonly occurs within 12 hours after birth
11. Normal Postnatal Closure The second stage usually is completed by 2 to 3 weeks produced by infolding of the endothelium, disruption and fragmentation of the internal elastic lamina replacement of muscle fibers with fibrosis permanent sealing of the lumen to produce the ligamentumarteriosum
12. mechanisms responsible for the initial postnatal closure of the ductusarteriosus are not fully understood increase in pO2, as occurs with ventilation after birth, constricts the ductusarteriosus prostaglandins play an active role in maintaining the ductusarteriosus in a dilated state PGE1, PGE2, and PGI2 dilate isolated ductusarteriosus strips or rings from term fetal lambs
13. At birth, the placental source is removed, and the marked increase in pulmonary blood flow allows effective removal of circulating PGE2
14. INCIDENCE OF PDA increased dramatically over the last two decades improved survival rate of premature infants incidence is approximately 0.02 to 0.04 percent among term infants born at sea level slight female predominance incidence is as high as 60 percent in infants born before 28 weeks gestation
15. Clinical History The diagnosis of PDA canot be made at birth The murmur emerges after few days as the pulmonary vascular resistance falls History of prematurity is very important. Premature babies with respiratory distress tend to have large shunts PDA is moe common in females with a ratio of 2:1
16. Family history is important , as it tends to recur in siblings Rubella infection to mother during the first trimester is a common cause maternal coxsackie virus infection is another cause Low birth weight is common, even in small shunts More common in children born in October to January
21. Small DuctusArteriosus the resistance to flow across the ductusarteriosus is high only a small left-to-right shunt develops Pulmonary blood flow is increased only minimally left ventricular failure does not occur Most of the infants are asymptomatic Murmur is detected on routine physical examination.
22. Moderate DuctusArteriosus In infants a moderate shunt produces symptoms of heart failure Poor feeding, irritability, and tachypnea are present symptoms ordinarily increase until about the second to third month
23. Large DuctusArteriosus Infants with a large PDA are invariably symptomatic They are irritable, feed poorly, fail to gain weight and sweat excessively They have increased respiratory effort and respiratory rates prone to develop recurrent upper respiratory infections and pneumonia symptoms indicative of severe left ventricular failure with pulmonary edema may occur early in infancy
24. Patients with reversed shunt Small number of cases High pulmonary vascular resistance, from infancy Effort dyspnea is the most common symptom Symptoms of left ventricular failure are absent Hoaseness of voice may be present. Cyanosis may be overlooked. There is marked leg fatigue and absence of dyspnea Rarely patients may have swelling and pain in lower limbs.
25. Physical apperance Physical underdevelopment due to a large shunt Maternal rubella syndrome: cataract, deafness and mental retardation Rocker bottom feet and loose skin is present in trisomy 13 In this syndrome assosiated VSD is usually present
26. Examination Differential cyanosis and clubbing is pesent in shunt reversal It can be brought out by exersise or a warm water bath Useful to have patient sit with hands and feet together.
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28. Arterial pulse A wide pulse pressure is present Pulse has a brisk rise, single peak and rapid collapse Diastolic pressure is low, systolic is high The peripheral pulses are bounding If the shunt is small or if there is pulmonary hypertension the bounding pulse is absent
29. JVP JVP is normal in small shunts In patients of cardiac failure the jvp is elevated and prominent A and V waves are present Prominent A waves are present in high pulmonary resistance
30. Auscultation The classic murmur of uncomplicated PDA rises to peak in latter systole Continues without interruption through the second heart sound Declines in intensity in diastole a silent interval may be present towards the end of diastole
31. Continious murmur A small duct results in a soft , high frequency continuous murmur A larger duct causes a loud noisy machinery murmur Loud murmur becomes soft if there is narrowing of the duct. The murmur is dependent on the pressure difference between aorta and pulmonary artery
32. Progression of murmur As the diastolic pressure of pulmonary artery increases the patient is left with a holosystolic murmur As pulmonary hypertension progresses further the systolic component also disappears Right to left flow across PDA does not have a murmur With increasing PH Gibson murmur is abolished Findings of pulmonary hypertension are present
33. Newborn In newborns the classic murmur is absent Only a soft systolic murmur may be present this is due to high pulmoary pressures However the signs of cardiac failure are present
34. Second heart sound Paradoxical spitting is present in patients of large left to right shunts due to Prolonged LV ejection and short RV ejection Difficult to detect on auscultation With shunt reversal the second heart sound is closely split with loud pulmonary component
35. ECG Small ductus ECG may be normal Variation in ecg depend on the volume overload of LV and pressure overload of RV Usually have sinus rhythm P waves are notched, bifid and prolonged s/o left atrial enlargement With development of pulmonary hypertension signs of biatrial enlargement are present
36. PR interval is prolonged in 10 to 20 percent of patients QRS axis is normal Volume overload of left ventricle results in deep s waves in v1, tall r waves I v5 to v6, deep q waves and tall t waves A large shunt with pulmonary hypertension results in features of biventricular hypertrophy Large equidiphasic complexes are present from v1 to v6
37. ECG in right to left shunt In PDA with right to left shunt peaked narrow right atrial P waves appear in 2,3,and v1 QRS axis shows right axis deviation Right ventricular hypertrophy R waves in v5, v6 remain tall bur the q waves and the tall t waves disappear
38. X ray chest Variation in XRAY depend on size, duration and direction and pulmonary pressures The ductus may be seen as a convexity between aorta and pulmonary artery In older patients calcium may be depoisted
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40. Left to right shunt causes increase in pulmoary plethora Pulmonary trunk and main branches are dilated Ascending aorta is enlarged in adults LA and LV are enlarged RA and RV dilatation occurs when pulmonary hypertension is present
41. Right to left shunt RV is hypertrophied Pulmonary trunk and main branches are dilated Peripheral vasculature is reduced Ascending aorta is normal sized Patients who have shunt reversal have larger hearts Both RV and LV enlargement is seen
42. Echocardiography A complete echocardiographic evaluation of the PDA includes two-dimensional imaging of the ductus, evaluation of the degree of shunting at the ductus, and evaluation of pulmonary artery pressure using Doppler echocardiography
43. Anatomic assessment Most commonly, the ductus is imaged in the parasternal and suprasternal notch views In the high parasternal short axis view, with the transducer oriented leftward toward the pulmonary artery bifurcation, the ductus can be imaged coursing between the pulmonary artery and the descending aorta Absolute quantification of its diameter is the best way to determine its presence or absence
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45. In the suprasternal notch window, the ductus arises from the descending aorta at the level of the left subclavian artery, and courses anteriorly to join the pulmonary artery
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48. Color flow mapping is particularly helpful in the setting of a small PDA, Determination of the origin of the retrograde flow into the pulmonary artery using two-dimensional imaging as well as color flow mapping is crucial to avoid confusion of the patent ductus with other aortopulmonary shunts
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50. The Size of the Left Atrium Left atrial (LA) enlargement signifies increased pulmonary venous return because of left-to-right ductal shunting
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52. Left Ventricular Size This will enlarge as cardiac output increases with both increased pulmonary venous return and with increased diastolic run-off Descending Aortic Flow in Diastole The presence of a significant ductal shunt results in diastolic run-off to the pulmonary circulation
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54. Left Pulmonary Artery Diastolic Flow Velocity This is higher with large left-to-right shunts. Values less than 15cm/sec are seen when the duct is closed
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57. Hemodynamic assessment The pulmonary to systemic flow ratio (Qp:Qs) can be determined echocardiographically When the pulmonary artery pressure is lower than systemic arterial pressure, there is continuous left-to-right shunting demonstrated. The velocity of flow across the ductus, measured by either pulsed or continuous wave Doppler, can be translated into the gradient between the aorta and the pulmonary artery
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59. When the pulmonary artery pressure is equal to systemic pressure, pulsed Doppler within the ductus demonstrates systolic right-to-left shunting, with diastolic left-to-right flow within the vessel
60. Cardiac Catheterization Color Doppler flow mapping is generally as sensitive as cardiac catheterization for detecting even a small PDA In children with pulmonary hypertension, determining the exact location of the shunt can be difficult Right heart catheterization alone usually suffices to confirm the diagnosis an additional lesion such as ventricular septal defect is suspected
61. An increase of pulmonary arterial blood oxygen content of >0.5 mL/dL or a saturation increase of >4% to 5% from that in right ventricular blood indicates a significant left-to-right shunt at the pulmonary arterial level An increase in oxygen saturation in pulmonary arterial blood is not diagnostic of a PDA, but may be present in lesions such as aortopulmonary window or a high ventricular septal defect
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63. a small communication, pulmonary arterial blood pressures are normal, but systemic arterial pulse pressure may be slightly widened a moderate-sized defect, 1. pulmonary arterial systolic, diastolic, and mean blood pressures may be slightly elevated. 2. Systemic arterial diastolic blood pressure falls, 3. whereas systemic arterial pulse pressure increases
64. large shunt hemodynamics pulmonary and systemic arterial pressures are equal, left atrial mean pressure may be increased substantially, and a prominent V wave is seen. Left ventricular end-diastolic pressure may be elevated, a diastolic pressure gradient between the left atrium and left ventricle is demonstrated. A small systolic pressure difference between the left ventricle and aorta is also encountered
65. Angiography it is the most effective test for defining the anatomy of the PDA Contrast medium is injected into a catheter passed through the PDA into the aorta from the pulmonary artery or into the aorta retrogradely from the femoral artery PDA usually is widely dilated, and the ductus narrows down at the pulmonary arterial end
66. the lateral projection, or occasionally the left anterior oblique projection, demonstrates the anatomy most clearly The AP camera can be positioned in the right anterior oblique caudal position to demonstrate the PDA selective descending aortography is essential in patients of VSD or ASD to demonstrate PDA
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68. Magnetic Resonance Imaging simpler techniques such as two-dimensional echocardiography Doppler evaluation accurately define the anatomy These studies can be of use in adolescents or adults with poor echo windows Velocity-encoded cine MRI imaging for estimation of left-to-right shunting may have additional clinical utility
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70. Percutaneous closure A variety of devices have been used for percutaneous closure of a PDA It is the standard of care in most patients Exception in premature and small infants with large shunts Have been available for last 20 years
71. Coils Stainless steel Gianturcocoils Earlier used for AV malformations For duct closure the PDA should be less than 2 mm in diameter, long to accommodate loops and should have sufficient aortic ductaldiverticulum The coils are deployed in a retrograde fashion from the aorta Coil embolisation is a dangerous complication Modified coils with release mechanism are available
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74. Multiple coils are used for large PDA PDA closure rate are around 95 to 100% at 2 years Residual shunt causes haemolysis Modifications available are Giantruco-grifika vascular occlusion device Nit occlud PDA occluder
75. Duct occluder device AMPLATZ duct occluder is only device which is FDA approved Cone shaped device Antegrade venous approach Delivery cable- release notch 98% closure at 6 months in large PDA Complications are left pulmonary artery stenosis, aortic coarctation Small ducts are avoided
