Truncus Arteriosus

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1. Definition

One great artery arising from base of heart with single semilunar "truncal" valve

This truncal artery gives origin to

Coronary arteries

Systemic arteries

One or two pulmonary arteries

Ventricular septal defect below semilunar valve

2. Morphology

Classified according to origin of PA (Collett and Edwards) or development of aorticopulmonary septum and presence or absence of interrupted aortic arch (van Praagh)

Truncal artery

Originates more from the right ventricle

Gives rise to the coronary arteries and one or two pulmonary arteries

Pulmonary artery

Originates just downstream from the truncal valve on left posterior aspect of truncal artery

Single orifice with short main PA is Type I (Collett and Edwards)

Double orifice with right and left PA is Type II

Origin of RPA and LPA separately from lateral wall of truncal artery is Type III

Persistent Truncus Arteriosus

3. Coronary arteries

Usually arise from the sinus of Valsalva

Semilunar valve

Tricuspid = 50-66%

Four cusps in the remainder

VSD

High, anterior, below semilunar valve

Right ventricle

Conal septum is absent from the RV outflow tract

Hypertrophied and enlarged

4. Associated Anomalies

Interrupted aortic arch or coarctation with PDA = 10-20%

Persistent left superior vena cava = 10%

DiGeorge syndrome

Right aortic arch (in absence or IAA) = 25-30%

5. Pathophysiology

Complete mixing lesion

Pulmonary overcirculation in systole and diastole

Early development of pulmonary vascular disease

Development of CHF as pulmonary vascular resistance falls

6. Clinical Features

Symptoms

Tachypnea, tachycardia, irritability

Physical Examination

Signs of CHF

Collapsing pulses

Left parasternal systolic murmur

Chest x-ray

Marked cardiomegaly

ECHO and Cardiac Cath

Single great artery from heart, VSD

Catheterization
Catheterization

7. Natural History

2.8% of congenital heart defects

50% die in first month

88% dead by one year

8. Treatment

Early operative intervention

Palliative operations are not useful and complicate later repair

Complete primary repair

Revision of RVOT repair later

9. Principles of Operation

Deep hypothermia, circulatory arrest or hypothermia with low flow

Close VSD to right of truncal valve

Truncal valve repair / replacement if necessary

Remove PA from aorta, repair aorta

RVOT reconstruction, conduit or primary anastomosis (PA to RV)

Modified ultrafiltration

Anatomy
Aortic Incision
Graft Anastomosis
RVOT Repair
RVOT Repair

10. Results

Hospital mortality 16%

Risk Factors

Older age at repair

NYHA functional class

Predominance of the origin of the truncal artery

Small pulmonary arteries

Truncal valve abnormalities

Early risk neutralized by use of allograft root replacement

Major associated cardiac anomalies

11. Late Results

15-year survival 83%

Risks for late death:

Truncal valve insufficiency (pre-repair)

Interrupted aortic arch

Short X-C time (?)

Freedom from reoperation related to truncal valve insufficiency