Congenital Heart Disorders – Disorders with Decreased Pulmonary Blood Flow
Disorders with Decreased Pulmonary Blood Flow
Obstruction to pulmonary blood flow decreases the flow of the blood in the pulmonary circulation. Because of the obstruction present, pressure of the right side of the heart increases. Increase pressure of the right side of the heart can open the foramen ovale at birth (Atrial Septal Defect) or ventricular septal defect (VSD) can be present. This results to the invasion of deoxygenated blood in the systemic circulation. Disorders under this classification of congenital heart disease include tetralogy of fallot or tricuspid atresia.
Tricuspid valve is located in between the right atrium and ventricle. This flap of tissue opens to pressure to allow blood to be drained in the right ventricle to the pulmonary circulation. In tricuspid atresia (atresia means absence of opening), as the name implies, the tricuspid valve is absent or completely closed. This prevents the blood to enter the right ventricle.
Due to the increasing pressure of the right atrium, the foramen ovale opens at birth resulting to an astrial septal defect. The blood crosses the foramen and goes directly into the atrium bypassing the step of oxygenation. Thus, blood is pumped into the systemic circulation completely deoxygenated. Blood can be shunted back to the lungs for oxygenation if the ductus arteriosus is patent. Open foramen ovale and patent ductus arteriosus can meet a child’s oxygenation needs.
When these structures are closed the infant will developed the following clinical manifestations:
Tetralogy of fallot presents with four cardiac anomalies namely:
- Ventricular Septal Defect (VSD) – usually large. Opening between the right and left ventricles.
- Pulmonary stenosis – narrowing of the pulmonary valve or pulmonary artery distal to it.
- Dextroposition (overriding) of the aorta – aorta overrides both ventricles
- Hypertrophy of the right ventricle
- Cyanosis (bluish skin)
- Polycythemia (increase in the number of red blood cells) – the body attempts to provide the body with oxygen by increasing the RBC levels. Elevated RBC concentration in the blood results to increased viscosity and clots in the blood vessels may occur. Complications of polycythemia include thrombophlebitis, embolism or cerebrovascular accident.
- Severe dyspnea
- Growth restriction
- Clubbing of the fingers
- Squatting or knee-chest position when resting (physiologic relief from an overstressed heart by trapping blood in the lower extremities)
- Syncope (fainting)
- Tet spells (hypoxic episodes) – follows after prolonged crying or exertion
Images from health.allrefer.com, nlm.nih.gov, healthline.com