Answer
1) Fetal circulation to Post natal circulation
a) Umbilical vein carries oxygenated blood and nutrient from the placenta.
b) Blood from umbilical vein will goes to portal circulation (for liver to process nutrients) and ductus venousus (shunt that bypass liver channel the blood into hepatic vein) which drain the oxygenated blood to right atrium via inferior vena cava.
c) 1/3rd of blood from right atrium is shunted to the left atrium through foramen ovale.
d) Blood pumped from right ventricles enter pulmonary trunk and then shunted into aortic arch through ductus arteriosus
e) Deoxygenated blood and wastes then carried to the mother placenta via umbilical arteries.
f) After delivery and baby took the first breath, there will be a change from fetal to postnatal circulations. Foramen ovale will closes shortly after birth and fuses completely in first year. Ductus arteriosus will close soon after birth and become ligamentum arteriosum in about 3 months. Ductus venosus becomes ligamentum venosum. Umbilical arteries become medial umbilical ligaments and umbilical artery (patent anterior division of internal iliac artery). Umbilical vein become ligamentum teres.
2) Bluish discoloration of skin and particularly mucous membrane is termed as cyanosis which occurs due to excessive amount of reduced hemoglobin in the capillary bed. It can be noticed when the concentration of reduced hemoglobin is more than 3-5 g/dL.
3) Cyanosis of Heart and Lung origin
|
| Cardiac | Lung |
| Respiration | Comfortable at rest | Tachypnoeic, distress, Subcostal recession |
| Crying | Worsen the cyanosis | Cyanosis improved |
| Auscultation | Cardiac murmurs may present | Rale, crackles, wheezing |
| Chest X ray | Abnormal Cardiac silhouette with lung field shows Normal, decreased vascularity or pulmonary vascular congestion | Normal cardiac silhouette and lung field may shows evidence of pneumonic changes, respiratory distress features, ground glass opacities and atelactasis. |
| ECG | Abnormal rhythm or axis | normal |
| PCO2 level | Normal or low | Increase |
| Hyperoxia test | No significant raised arterial Pao2 during administration of 100% oxygen | prompt response to 100% oxygen |
4) The chest X ray, AP view shows the following finding
a) Cardiomegally
b) Narrowed mediastinal shadow
c) Elevated cardiac apex
5) Causes of congenital cyanotic heart disease includes
Decreased flow
a) Tetralogy of Fallot
b) Tricuspid Atresia
c) Severe Pulmonic Stenosis
d) Double Outlet Right Ventricles with Pulmonary Stenosis
e) Ebstein’s anamoly
Increased Flow
f) Transposition of great vessels
g) VSD with pulmonary atresia
h) Truncus Arteriosus
i) Hypoplastic left heart
j) Single ventricle
k) Totally anomalous pulmonary venous return (TAPVR) with infradiaphragmatic obstruction
6) Differential diagnosis for this patient
a) Tetralogy of Fallot
b) Pulmonary Atresia with large ventricular septal defect.
7) Three diagnostic test that could be performed includes
a) Echocardiography
b) Cardiac catherization
c) Angiography
8) Outline of management for this patient
a) Stabilization of patient airway, breathing and circulation
b) Oxygen with high flow mask
c) Obtain intravenous access
d) Prostaglandin E1 infusion to maintain patency of ductus arteriosus
e) Blalock-Taussig shunt(direct anastomosis of the subclavian artery to the pulmonary artery)
f) Definitive repair of the defect once patient stabilize.
g) Referral to welfare services
h) Psychosocial support to the mother.
Notes: This patient has pulmonary atresia with large Ventricular septal defect and small patent ductus arteriosus. Surgery is required for this patient.