A 29-year-old immigrant male presented to the cardiology clinic with complaints of progressively worsening shortness of breath on exertion, headache, and blurring of vision. Since childhood, he had been experiencing similar symptoms, but no diagnosis had been made, nor had he received regular treatment. The patient reported that his symptoms reduce with squatting and with 30-minutes rest.
On examination, saturation of oxygen was 92% on room air. A harsh holosystolic murmur was heard on auscultation at the left sternal border with a sternal heave. The rest of the physical examination was normal. Digital clubbing was absent.
Complete blood count showed a hemoglobin level of 20 g per deciliter (reference range, 13 to 17). Electrocardiography revealed the right bundle-branch block with sinus rhythm. Echocardiography revealed the following:
- The aorta (Ao) overriding a large ventricular septal defect (VSD) (Panel A)
- Right ventricular hypertrophy (RVH)
- Sub pulmonic stenosis (PS) (Panel B)
These findings confirmed the diagnosis of tetralogy of Fallot. Right ventricular outflow tract obstruction was responsible for the characteristic harsh holosystolic murmur.
Surgery was planned to repair the defect. Pulmonary valvotomy was performed along with the closure of the ventricular septal defect. The muscle bundles in the right ventricular outflow tract were resected, and patch augmentation of the infundibulum and main pulmonary artery was performed.
At the 2-month follow-up, the patient had recovered well. His symptoms including dyspnea, visual disturbance, and headache had resolved with no further episodes
Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease present in infants. It is named so because it is a combination of 4 defects:
- Ventricular septal defect (VSD)
- Right outflow tract obstruction (Pulmonary stenosis)
- Right ventricular hypertrophy
- Overriding Aorta (Aorta lies over the VSD, instead of its normal origination form the left ventricle)
The cause of TOF is largely unknown, some of the contributing factors that are associated with TOF include:
- Advanced maternal age > 40 years
- Malnutrition during pregnancy
- Infections during pregnancy, including rubella
- Diabetic mother
- Genetic diseases example a child with Down syndrome has higher chances of TOF
- DiGeorge syndrome
- Branchial arch abnormalities
Factors that worsen the symptoms include dehydration, physical exercise, infections, stress, acidosis, and certain drugs, including beta-adrenergic agonists.
Certain maneuvers like squatting and knee-chest position improve the symptoms as these increase systemic vascular resistance and increase the preload, which results in the shunt reversal at the ventricular septal defect; therefore, a reduction in symptoms.
In diagnosed infants, surgical repair is done approximately at the age of 6 months. Earlier surgery may be required in cases of a sudden or progressive decrease in oxygen saturation.
Reference:
John Dickey, M. a. (2020, June 18). Unrepaired Tetralogy of Fallot in Adulthood. Retrieved from The New England Journal of Medicine: https://www.nejm.org/doi/full/10.1056/NEJMicm1912128
