Truncus Arteriosus
CICU lecture
January 7, 2011
Chrissy Sarlone
Features
• A single vessel arises from
the heart
• Origin to the coronary
arteries, pulmonary
arteries, and aorta
• Truncus overrides VSD
• 1-2.5% of all congenital
heart disease
Features
• Truncal valve is usually a
single valve with 2 to 4
cusps
• PDA absent in 50% of
patients
• Size of PDA and aorta
vary inversely
Embryology
• Failure of normal
septation and the
division of the
embryonic truncus into
the aorta and
pulmonary artery
• VSD forms from an
absent or minimal conal
septum
Classification
48-68%
29-48%
6-10%
Risk Factors
• Genetics: Recurrence rates vary from 1.2% to
13.6% with complex disease(Allen et al, 2000 )
• IDM (12-13 fold increase in Baltimore
Washington Infant Study)
– Ferencz, Teratology, 1990
• Fetal exposure to retinoic acid
Associated Defects
• Truncal Valve Insufficiency/Stenosis-detected
by 24 weeks gestation
• Right sided aortic arch- 30%
• Interrupted aortic arch- 11-20%
– Type B
• Coronary Artery Anomalies
22q11 Microdeletion Syndrome
• 1/3 of infants
• Higher risk if associated aortic arch anomaly
• Important to assess for hypocalcemia and
immunodeficiency as these complicate the
course
Physiology
• With the large VSD, the
combined cardiac
output travels through
the truncal valve
• PBF depends upon the
balance between PVR
and SVR
Physiology
• After birth, high PVR leads to
almost equal distribution of
Qp:Qs
• As the PVR falls, Qp:Qs
increases at the expense of
systemic oxygen delivery and
CHF ensue
Delivery Room Management
• Usually no intervention needed in the DR
• Several Factors to Consider:
– Truncal valve insufficiency
– Pulmonary artery hypoplasia
• If moderate or greater truncal valve
insufficiency, the infant will be gray at birth
because of low Mvsat and decreased systemic
oxygen delivery
“The Unknown” Presentation
• If not prenatally diagnosed and no truncal valve
insufficiency or PA hypoplasia, there may be mild
cyanosis due to complete mixing
• Once PVR falls, sats will range 90% and higher, no
visible cyanosis (increase Qp:Qs ratio)
• Over several weeks, the infant will become
symptomatic with signs of CHF due to increased PBF
and as a result decreased systemic oxygen delivery
– Tachypnea, retractions
– Poor feeding and growth
– Excessive sweating
Clinical Presentation
• 22q Microdeletion Syndrome (DiGeorge)
– Hypertelorism, micrognathia, low set and
posteriorly rotated ears, bulbous nose
• Physical Exam
– Bounding pulses
– Increased pulse pressure
– Normal first heart sound, followed by single S2
– Systolic ejection click from single semilunar valve
Clinical Presentation
• Truncal valve insufficiency
– Diastolic high-pitched murmur along left sternal
border
• Heart Failure
– Tachypnea, rales, retractions
– Hepatomegaly
• PA Hypoplasia
– Normal peripheral pulses and near normal pulse
pressures
– Cyanosis
Studies
• EKG
– Normal QRS or minimal right axis deviation
– Increased Pulmonary Blood Flow: Combined
biventricular hypertrophy, left atrial enlargement
– Decreased PBF: right ventricular hypertrophy only
• X-ray
– Cardiomegaly
– Increased pulmonary vascularity or no pulmonary
vascularity on side without PA
– Right aortic arch
X-ray
Normal Chest X-ray
Truncus Arteriousus
Studies
• Echo
– Required for diagnosis confirmation and anatomic
assessment of truncal valve, aortic arch
orientation/interruption, VSD, coronary arteries
and pulmonary arteries
• Cardiac catheterization/Angiography
– Undiagnosed older patients to assess pulmonary
vascular disease
– Coronary artery and pulmonary artery mapping
Management
• Early surgical repair is key to prevent pulmonary
vascular disease
– Can develop by 4-6 months of age
– Repair after PVR has fallen
• Treat CHF: diuretics, afterload reduction, fluid
restriction
– Vent strategies: sats 85-90%, PCO2 of 40 mmHg
• Prostaglandin infusion: If the ductus is present,
consider prostaglandins if there is restriction to
pulmonary blood flow
Surgical Repair Goals
• Detach pulmonary arteries from truncus and if
separated (Type II or III) create anastomosis
• Patch Closure of the aorta
Surgical Repair Goals
• Closure of the VSD via right ventriculotomy
(via patch baffle) with LVOT blood flow
directed to truncal valve
• Creation of RV to PA continuity via homograft
conduit usually, rarely direct connection of
MPA to Anterior RV
• Leave PFO for “pop-off” elevated RV enddiastolic pressures
Other Surgical Factors
• Truncal Valve Insufficiency
– Manage conservatively if mild to moderate
– Suture prolapsing leaflet to other leaflets making
tricuspid or bicuspid valve
– May need to replace valve if severe TV insufficiency
with homograft valve, mechanical valve in older
children
• Interrupted Aortic Arch
– Repaired at the same time
– May require homograft to connect ascending aorta
and aortic arch
Post-Op Complications
• Decreased LV output (Qs) due to RV systolic (RV
infundibulotomy), RV diastolic dysfunction, and
increased PVR
– Decreased RV filling
– Decreased RV output
– Decreased preload to the LV
– PFO extremely beneficial (Shunting Right to Left)
Better to be “blue” than “gray”
Post-Op Complications
• Pulmonary Hypertension
– Can be present post-op despite no disease pre-op
– High Qp:Qs pre-op with excessive flow
• Postop hemorrhage
– Tamponade
• AV block
– Conduction injury from VSD repair
– May require cardiac pacing
Long-Term Outcomes
• Likely to need replacement of RV to PA
conduit as child grows
• Potential replacement of truncal valve
• Progressive Left Ventricular Dysfunction if
there is moderate to severe truncal valve
insufficiency
Morbidity and Mortality
Nichols 1995
Morbidity & Mortality
• Decreased with earlier repair over the years
• 90% survival at CCHMC
• Eur J Cardiothorac Surg 2010
– 83 patients in Prague
– Post-op mortality of 46% between 1981-1997 and
4% between 1997-2008,
– 54% with Type I, 12% with severe truncal valve
insufficiency, 17% with IAA
– 75% patients required conduit replacements
within 5 years, 13% with balloon dilation or stent
placement in conduit
Truncal Valve Replacement
• Ann Thorac Surg, 2010: Utah
– 1995 to 2008, 27% of patients with truncus
arteriosus underwent truncal valve
repair/replacement initially
– Repeated repair or replacement indicated when
severe regurgitation with symptoms, LV dilatation
– 30% underwent second truncal valve operation
(mean age 47 +/- 33 months) for severe
regurgitation
– 70% required no intervention after 5 years, 50%
after 7 years
Truncal Valve Replacement
Nichols 1995
Take Home Points
• 1-2% of all congenital heart disease
• Associated defects: Truncal valve
stenosis/insufficiency, right sided arch,
IAA
• 22q11 microdeletion syndrome
• May not be cyanotic at birth
• As PVR falls, Qp:Qs increases and
systemic oxygen delivery decreases
Take Home Points
• Early repair key to prevent pulmonary
vascular disease, impaired systemic
oxygen delivery and decrease mortality
• High risk of replacement of RV to PA
conduit and potentially the truncal valve
as the child grows
References
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Allen, H. D., Adams, F. H., & Moss, A. J. (2000). Moss and adams' heart disease in infants,
children, and adolescents : Including the fetus and young adult (6th ed.). Philadelphia, PA:
Lippincott Williams and Wilkins.
Artman, M., Mahony, L., & Teitel, D. F. (2002). Neonatal cardiology. New York: McGraw-Hill,
Medical Pub. Division.
Henaine, R., Azarnoush, K., Belli, E., Capderou, A., Roussin, R., Planche, C., et al. (2008). Fate
of the truncal valve in truncus arteriosus. The Annals of Thoracic Surgery, 85(1), 172-178.
Kaza, A. K., Burch, P. T., Pinto, N., Minich, L. L., Tani, L. Y., & Hawkins, J. A. (2010). Durability of
truncal valve repair. The Annals of Thoracic Surgery, 90(4), 1307-12; discussion 1312.
Nichols, D. G. (1995). Critical heart disease in infants and children. St. Louis: Mosby.
Stark, J., De Leval, M., & Tsang, V. T. (2006). Surgery for congenital heart defects (3rd ed.).
Chichester ; Hoboken, NJ: J. Wiley & Sons.
Tlaskal, T., Chaloupecky, V., Hucin, B., Gebauer, R., Krupickova, S., Reich, O., et al. (2010).
Long-term results after correction of persistent truncus arteriosus in 83 patients. European
Journal of Cardio-Thoracic Surgery : Official Journal of the European Association for CardioThoracic Surgery, 37(6), 1278-1284.