Hemitruncus is a rare congenital heart defect where one pulmonary artery arises from the aorta and the other from the right ventricular outflow tract. It leads to severe pulmonary arterial hypertension and most patients do not survive beyond one year without repair. It is commonly associated with other cardiac anomalies which worsen the prognosis. The pathophysiology involves one lung receiving blood at systemic pressures while both lungs experience pressure and volume overload from the right ventricle. Urgent surgical repair is needed to correct the anatomy and prevent irreversible pulmonary vascular disease.

1. HEMITRUNCUS
ONE PULMONARY ARTERY FROM AORTA, OTHER ONE FROM
RVOT

2. NATURAL HISTORY
 INCREASE PBF
 SEVERE PAH
 SURVIVAL BEYOND 1 YR IS NOT POSSIBLE
 ASSOCIATED CARDIAC ANOMALIES MAY WORSEN THE PROGNOSIS EVEN
FURTHER
 THE PREVALENCE OF HEMITRUNCUS BEYOND INFANCY IS NOT KNOWN AS
MAJORITY OF THE SERIES HAVE PATIENTS WHO ARE BELOW ONE YEAR OF
AGE AND ONLY SPORADIC CASES ARE ENCOUNTERED IN LARGER SERIES
 MOST COMMONLY ASSOCIATED WITH TOF

3. PATHOPHYSIOLOGY
• FIRST DESCRIBED BY FRAENTZEL IN 1868
• RPA FROM AORTA MOST COMMON(X4-8 TIMES)
• AFFECTED LUNG IS PERFUSED AT SYSTEMIC PRESSURE AND THE REMAINING
LUNG IS EXPOSED TO THE ENTIRE OUTPUT OF THE RIGHT VENTRICLE
• PULMONARY CIRCULATION OF BOTH LUNGS ARE EXPOSED TO PRESSURE AND
VOLUME OVERLOAD IN HEMITRUNCUS
• SERIOUS PULMONARY VASCULAR DISEASE AT THIRD MONTH :PULMONARY BLOOD
FLOW, CIRCULATING VASOCONSTRICTOR , NEUROGENIC CROSSOVER FROM
UNPROTECTED LUNG AND LEFT VENTRICULAR FAILURE

4. MANAGEMENT
THE KEY IS EARLIEST REPAIR

5. • END TO END ANASTOMOSIS WITH A SYNTHETIC GRAFT
• INTERPOSITION OF A HOMOGRAFT PATCH
• AORTIC FLAP OR INTERPOSITION OF AUTOLOGOUS PERICARDIAL PATCH FOR
INCREASING THE LENGTH OF THE ANOMALOUS PA
• DIRECT ANASTOMOSIS TO AVOID CONDUIT RELATED PROBLEM

6. LOOP HOLES
• PVRI IS FALLACIOUS(CAN BE RECTIFIED BY USING FLOW RATE BY
CATHETERIZATION AND MRI
• PVRI ASSESSMENT CAN BE IMPROVED BY USING THE FORMULA 1/R = 1/R1 +
1/R2
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*PRESTON RR, WILSON TE, EDITORS. CARDIOVASCULAR REGULATION. IN:
LIPPINCOTT'S ILLUSTRATED REVIEWS: PHYSIOLOGY. PHILADELPHIA:
LIPPINCOTT WILLIAMS AND WILKINS; 2012. P. 232-50