PDA

It is a continuous murmur, due to kinking and partial obstruction of one of the large veins in the neck.

• It is found in the neck above the clavicle and upper part of chest, more on the right side of sternum.
• The hum can be obliterated by pressure on the neck or lying down or altering the position of neck (as there is reduction of venous obstruction).
• It is accentuated by sitting with head extended and turned to the side opposite to that auscultated.
• Venous hum has no clinical significance, commonly present in children, should not be confused with any pathology.

* Long Cases in Clinical Medicine, ABM Abdullah Page: 249

The continuous murmur begins after the first heart sound and peaks at the second heart sound, after which it trails off, i.e. Murmur can span the whole of systole and diastole, obscuring second heart sound.

Read more about murmur at Examination of cardiovascular system

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 60

Differential clubbing and cyanosis mean cyanosis and clubbing of toes, not of the fingers.

• Cause is pulmonary hypertension with shunt reversal in patent ductus arteriosus.

Read more about clubbing at History and general examination

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 60

Common in female, M:F = 1:3. Probable etiological factors are:

• Maternal rubella in the first trimester
• Birth at high altitude with continuous prenatal hypoxia
• Prematurity.
• Low-birth weight
• Maternal use of prostaglandin antagonists, i.e. NSAIDs.

Note:

In PDA, it allows blood to flow from aorta to pulmonary artery. Up to 50% of left ventricular output may enter into pulmonary artery, because pressure in aorta is higher.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 60; Long Cases in Clinical Medicine, ABM Abdullah Page: 250

• During fetal life, ductus arteriosus connects pulmonary artery at its bifurcation to the descending aorta just below the origin of left subclavian artery and circulate oxygenated blood from pulmonary artery to aorta.
• After birth when baby takes breath, it closes spontaneously within few hours to days and remains as ligamentum arteriosum.
• In PDA, ductus arteriosus persists and allows blood to flow from aorta to pulmonary artery.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 60; Long Cases in Clinical Medicine, ABM Abdullah Page: 250

As follows:

• PDA
• Arteriovenous fistula (coronary, pulmonary or systemic)
• Aortopulmonary fistula (may be congenital or Blalock-Taussig shunt)
• Venous hum
• Rupture of sinus of Valsalva to the right ventricle or atrium.

* Long Cases in Clinical Medicine, ABM Abdullah Page: 250

The following murmurs may mimic continuous murmur (to and fro murmur)

• Mitral regurgitation and aortic regurgitation
• Ventricular septal defect and aortic regurgitation.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 60

Clinical Manifestations

Vary with the size of defect.

• Small defect may be asymptomatic
• Moderate to large defect: Generally results in–
  • Poor feeding
  • Poor weight gain (failure to thrive)
  • Dyspnoea
  • Profuse sweating with crying and feeding
  • Recurrent respiratory tract infections

General physical examination

• Appearance: May be normal or distressed
• Heart rate: Increased (tachycardia)
• Respiratory rate: Increased (tachypnoea)
• Pulse: High volume and collapsing pulse with wide pulse pressure.

Precordium

• Inspection: Hyperdynamic (Visible cardiac impulse in apical area and another impulse in pulmonary area)
• Palpation:
  • Apex beat is shifted to left, thrusting or heaving in character
  • A thrill may be palpable at 2nd left intercostal space (pulmonary area)
• Auscultation:
  • S1 is usually normal
  • S2 is often obscured by the murmur
  • Added sound: Continuous machinery murmur at 2nd left intercostal space near the sternum (maximal at mid clavicular line, murmur is prominent on expiration, may be heard posteriorly) is the classic finding.

* Step on to Paediatrics, Md Abid Hossain Mollah, 3rd Edition Page: 124; Short Cases in Clinical Medicine, ABM Abdullah, 5th Edition Page: 99, 100

Continuous murmur (machinery murmur like train in a tunnel), with late systolic accentuation.

* Long Cases in Clinical Medicine, ABM Abdullah Page: 250

As follows:

• Cyanosis and clubbing in lower limb, absent in upper limb (called differential cyanosis and differential clubbing).
• Murmur—quiet or absent or systolic only (diastolic disappears).
• Evidence of pulmonary hypertension.

* Long Cases in Clinical Medicine, ABM Abdullah Page: 250

A venous hum is best heard at the right of the sternum and diminishes or disappears in lying position, during expiration or compression of the right JVP.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 50

The murmur of PDA is heard loudest below the left clavicle and is equally loud posteriorly. This is not the case for pulmonary stenosis.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 50

The following investigations must be done

• ECG (normal or LVH. But RVH in Eisenmenger’s syndrome)
• X-ray chest (cardiomegaly with plethoric lung fields/increased pulmonary vascular markings. Cardiomegaly with oligemic lung fields in Eisenmenger’s syndrome)
• Echocardiography – 2D and color Doppler echocardiography (diagnostic)
• Cardiac catheterization in some cases
• Angiography (confirmatory).

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 61; Step on to Paediatrics, Md Abid Hossain Mollah, 3rd Edition Page: 124

Yes, as apex beat is displaced and thrusting in character.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 60

Murmur is gradually changing and presence of features of pulmonary hypertension.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 60

The typical continuous murmur is highly suggestive of PDA. However, any cause of continuous murmur should be excluded such as:

• Arteriovenous fistula (coronary, pulmonary or systemic)
• Venous hum
• Rupture of sinus of Valsalva to the right ventricle or atrium.

* Long Cases in Clinical Medicine, ABM Abdullah Page: 249

Treatment:

Counsel the parents about the disease, treatment options and prognosis.

Conservative management

• Prophylaxis for infective endocarditis
• Diuretics, ACEi for heart failure/left ventricular dysfunction

Definitive management

• In neonates-administration of prostaglandin inhibitors (intravenous indomenthacin or ibuprofen) can induce ductal closure if given within 72 hours of age particularly for premature babies.
  • Indomethacin : Given IV slowly over 30 minutes in the following dosage–
    • 1st dose: 0.2-0.3 mg/kg
    • 2nd dose: 0.2 mg/kg, 12-24 hours after 1st dose if PDA persists.
    • 3rd dose: 0.2 mg/kg, 12-24 hours after 2nd dose if PDA persists
  • Ibuprofen : Given orally
    • Day 1: 10 mg/kg
    • Day 2: 5mg/kg
    • Day 3: 5 mg/kg
• In older children-percutaneous ductal closure (device method)
• Surgical ductal closure
  • Surgical closure done before 1 year age

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 61; Step on to Paediatrics, Md Abid Hossain Mollah, 3rd Edition Page: 124, 125

Surgery is contraindicated when Eisenmenger’s syndrome develops and pulmonary hypertension is irreversible.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 61

The complications include

• Pulmonary hypertension
• Eisenmengers syndrome (reversal of shunt)
• Left ventricular dysfunction (volume overload, CCF(?)) – most common
• Infective endocarditis
• Ductal aneurysm and calcification
• Ductal rupture.

* Short and Long Cases in Clinical Medicine, HN Sarker Page: 60; Short Cases in Clinical Medicine, ABM Abdullah, 5th Edition Page: 101