PATENT DUCTUS ARTERIOSUS
 
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PATENT DUCTUS ARTERIOSUS

 

DEFINITION:

An acyanotic congenital heart disease characterized by prolonged patency of the ductus arteriosus.

EPIDEMIOLOGY:

  • incidence: 6-8% of all congenital cardiac lesions
  • age of first detection:
    • any
  • risk factors:
    • Trisomy-18, -13, -9, Cri-du-chat Syndrome; Charge and VATER Associations, Maternal PKU, Fetal Hydantoin Syndrome, Congenital Rubella Syndrome; Carpenter, Conradi, Crouzon, Smith-Limli-Opitz, Treacher Collins Syndromes
    • F:M (2:1)
    • infants:
      • 80% of infants <1,000 gm
      • 20% of premature infants
      • infants born at high altitude

PATHOPHYSIOLOGY:

1. Background

  • extent of shunt depends on the size of the ductus and pulmonary vascular resistance; in some cases, 70% of cardiac output may be shunted into the pulmonary circulation

2. Preterm

  • patency due to hypoxia and prematurity

3. Term

  • patency due to deficiencies in both the endothelial layer and muscular media of the ductus
  • rarely close spontaneously

CLINICAL FEATURES:

1. Symptoms

1. Asymptomatic

  • small defect with trivial L->R shunt
  • usually found on routine physical examination

2. Symptomatic

  • large defect with significant pulmonary hypertension
    • congestive heart failure
    • dyspnea
    • failure to thrive
    • feeding difficulties
    • profuse perspiration
    • recurrent lung infections

2. Signs

1. Periphery

  • wide pulse pressure with low diastolic pressure
  • bounding pulses (femorals, palmar)
  • cyanosis in lower extremities

2. Palpation

  • thrill @ 2nd L interspace radiating to the L sternal border and apex
  • parasternal lift (RVH) and apical thrust (LVH)

3. Auscultation

1. Heart Sounds

1. S1 - normal

2. S2 - loud

  • initially widely split due to prolonged RV ejection time due to increased RV blood volume
  • later single as pulmonary pressure approaches systemic pressure

2. Murmurs

1. Systolic

1. PDA Murmur
  • classically a continuous "machinery" murmur @ L 2nd & 3rd interspaces
  • with increased pulmonary pressure, the murmur is less prominent or absent in diastole

2. Diastolic

1. Relative Mitral Valve Stenosis
  • short mid-diastolic murmur at apex
  • increased blood flow across the mitral valve

3. Complications

  • infective endarteritis
  • pulmonary or systemic emboli
  • aneurysmal dilatation of the PA or the ductus
  • pulmonary hypertension
  • calcification or noninfective thrombosis of ductus

INVESTIGATIONS:

1. Chest X-Ray

  • cardiomegaly with prominence of RV, LV, both ventricles, LA and PA
  • increased pulmonary vasculature
  • prominent aortic knob

2. ECG

  • LVH -> biventricular hypertrophy -> RVH
  • LAH

3. 2D-Echo

  • PDA
  • volume overload of pulmonary arteries

MANAGEMENT:

1. Supportive

  • PDA's are well tolerated during childhood and there is no need for restriction of activity

1. Medical Management

1. Antibiotic Prophylaxis

  • adenoidectomy
  • dental surgery
  • oropharyngeal surgical procedures
  • tonsillectomy
  • any instrumentation of the genitourinary and lower intestinal tracts

2. Congestive Heart Failure

  • digoxin and lasix

2. Closure

1. Medical

1. Indomethacin

  • 0.2-0.3 mg/kg/dose IV q24h x 3 doses
  • indications: symptomatic newborns
  • contraindications:
    1. Absolute
    • PDA-dependent cardiac lesion
    • renal failure
      • creatinine >160 mmol/L
      • urea >9.0 mmol/L
      • oliguria <0.5-1.0 cc/kg/hr
    • necrotizing enterocolitis
    • thrombocytopenia <80,000
    2. Relative
    • hyperbilirubinemia
    • intraventricular hemorrhage

2. Surgical Ligation

  • indications:
    • failure of indomethacin to close duct in a symptomatic newborn
    • 1-2 years of age in an asymptomatic child
    • with increasing age there is an increased risk of death from either subacute bacterial endocarditis or CHF
  • case fatality rate <1%

 

 

 

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