TAPVR is found in 1-1.5% of all patients with congenital cardiac abnormalities; whereas, PAPVR is found at a rate of 0.6% in postmortem findings(1).
The early and late mortality rates for simple TAPVR are around 10% and 4%; whereas, for PAPVR they are 0% and <1%(1).
What Are The Differences Between PAPVR & TAPVR?
Partial Anomalous Pulmonary Venous Return (PAPVR) and Total Anomalous Pulmonary Venous Return (TAPVR) are both abnormalities of pulmonary venous blood flow, which are rare congenital heart deformities. In these, the pulmonary veins do not connect to the left atrium instead drain oxygenated blood to the right side of the heart. If all four pulmonary veins are abnormally connected then it is termed as TAPVR and if 3 or less than 3 pulmonary veins are anomalous then it is termed as PAPVR. TAPVR is more common in males whereas PAPVR is more commonly seen in females.
TAPVR can be classified into four different types namely:
- Supracardiac Type: The pulmonary veins drain into the superior vena cava or the left innominate vein
- Cardiac & Coronary Sinus Type: The pulmonary veins drain into a common vein connecting to the coronary sinus or right atrium
- Infracardiac Type: The four pulmonary veins drain into the portal vein
- Mixed Type: The right pulmonary veins drain into the right atrium or coronary sinus and left pulmonary veins to drain into the innominate vein via a vertical vein(1).
The classification of PAPVR includes:
PAPVR With Sinus Venosus Atrial Septal Defect (80-90% Of The Cases): Normally, the right upper or middle pulmonary vein drains into the superior vena cava or the right atrium.
Isolated PAPVR or PAPVR Without Atrial Septal Defect: Usually, a rare phenomenon and mainly the right upper pulmonary vein drain into the superior vena cava.
PAPVR With Complex Congenital Heart Disease Or Heterotaxia: The right pulmonary veins drain into the right atrium and associated with obstruction and pulmonary arterial hypoplasia
Scimitar Syndrome: The anomalous connection of the right pulmonary vein to the inferior vena cava with right lung sequestration, lung hypoplasia, and dextrapositioning of the heart to the right side(2).
Clinical Presentation Of TAPVR & PAPVR
Since both are congenital disorder and present by birth, neonates with TAPVR are symptomatic from the beginning; whereas, patients with PAPVR become symptomatic in middle age or remain asymptomatic throughout life depending on the number of pulmonary veins involved.
TAPVR patients present with cyanosis, shortness of breath, diaphoresis (sweating) on feeding, failure to grow, liver enlargement, right heart failure, systemic hypotension, metabolic acidosis, and pulmonary hypertension. TAPVR patients with obstruction additionally present with severe cyanosis and shortness of breath, tachycardia, and sometimes acute respiratory failure along with the above-mentioned symptoms(1).
The symptoms of PAPVR are usually mild or the patients are completely asymptomatic. Children are usually asymptomatic, except cardiac murmurs or intolerance to exercise. Adults may present with shortness of breath, arrhythmias, peripheral edema, right heart failure, lung infections, or hemoptysis in cases of pulmonary venous disease(2).
Management Of TAPVR & PAPVR
TAPVR and PAPVR both need to be managed very differently. TAPVR especially the obstructed type needs to be surgically corrected within hours to days of life; whereas, PAPVR can be managed medically without the need for immediate surgery. TAPVR patients can be stabilized medically with mechanical ventilation, inotropic drugs, nitric oxide inhalation preoperatively, prostaglandins, and ECMO (extracorporeal membrane oxygenation). The surgery of TAPVR is aimed at separating all the anomalous pulmonary veins contacts and connecting the pulmonary veins to the left atrium(1).
Generally, the prognosis of TAPVR patients is dependent on the degree of obstruction of pulmonary veins and other defects associated with it. The early and late mortality rates for simple TAPVR are around 10% and 4%; for TAPVR with pulmonary obstruction are 17 and 11%, respectively; for unobstructed patients, they are 4% and 6%, respectively; TAPVR associated with other cardiac abnormalities are 17% and 11%; whereas, for PAPVR they are 0% and <1%(1).