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Zorluk: OrtaPediatric Cardiovascular Disorders

A 4-month-old girl with trisomy 21 is evaluated in the pediatric clinic for poor feeding, diaphoresis during feeds, and inadequate weight gain over the past month. The mother reports that the infant has been breathing rapidly and occasionally wheezing. Temperature is 37.1°C (98.8°F), heart rate is 165/min, and respiratory rate is 65/min. Oxygen saturation is 95% on room air. Physical examination reveals a hyperactive precordium. Auscultation demonstrates a loud first heart sound (S1), a fixed and widely split second heart sound (S2), and a grade 3/6 holosystolic murmur best heard at the cardiac apex. A mid-diastolic rumble is also auscultated at the lower left sternal border. Lung auscultation reveals bilateral crackles and diffuse expiratory wheezing. The liver edge is palpable 3 cm below the right costal margin. Which of the following is the most likely underlying cause of this patient's current symptoms?

  1. Failure of endocardial cushion fusionCevap
  2. B
    Lower respiratory tract viral invasion
  3. C
    Chronic bronchial hyperreactivity
  4. D
    Decreased thyroxine production
  5. E
    Nonpathologic constitutional growth delay

Cevap

Failure of endocardial cushion fusion
The correct answer is failure of endocardial cushion fusion. This patient with Down syndrome (trisomy 21) is presenting with classic signs of congestive heart failure (diaphoresis with feeds, failure to thrive, tachypnea, crackles, and hepatomegaly). The physical examination findings of a fixed split S2, a holosystolic murmur, and a mid-diastolic rumble are highly characteristic of a complete atrioventricular septal defect (AVSD). Complete AVSD is the most common congenital heart defect in patients with Down syndrome and occurs due to the failure of the endocardial cushions to fuse during embryogenesis, leaving a central hole that includes an ostium primum atrial septal defect, an inlet ventricular septal defect, and a common AV valve.

Adım Adım Çözüm

1
Identify the patient's primary clinical syndrome based on the physical examination and vitals.
The patient exhibits diaphoresis with feeds, poor weight gain, tachypnea, crackles, wheezing ('cardiac asthma'), and hepatomegaly, which collectively indicate congestive heart failure with pulmonary and systemic venous congestion.
Recognizing heart failure is critical to differentiate the presentation from primary respiratory or endocrine issues.
2
Correlate the cardiac auscultation findings with the patient's underlying genetic condition.
The patient has Down syndrome (trisomy 21) and presents with a hyperactive precordium, fixed split S2, holosystolic murmur, and a mid-diastolic rumble. This constellation of findings is pathognomonic for a complete atrioventricular septal defect (AVSD).
Specific murmurs point to specific structural defects. The fixed split S2 indicates an atrial septal defect, the holosystolic murmur indicates a ventricular septal defect (or common AV valve regurgitation), and the rumble indicates relative stenosis across the common AV valve due to massive left-to-right shunting.
3
Determine the embryological origin of the diagnosed congenital heart defect.
A complete AVSD results from the failure of the superior and inferior endocardial cushions to fuse in the center of the heart.
The question asks for the underlying cause of the symptoms, requiring knowledge of the pathophysiology and embryology of the patient's specific congenital defect.

Anahtar Kavram

Complete atrioventricular septal defect (AVSD) is the most common congenital heart defect in patients with Down syndrome. It results from a failure of endocardial cushion fusion and typically presents with congestive heart failure at 1-2 months of age as pulmonary vascular resistance falls.
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Pediatric Cardiovascular Disorders

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