Topic 15: TA - part 2

Question 1

TA - definition ?

Answer 1

TruncusArteriosus (or persistent truncus arteriosus) a rare type of congenital heart disease in which a single blood vessel (truncus arteriosus) comes out of the right and left ventricles, instead of the normal two (pulmonary artery and aorta)

Question 2

If untreated- what 2 probs occur with TA?

Answer 2

I. Too much pulmonary blood flow
II. The blood vessels to the lungs become permanently damaged. Pulmonary HTN develops.

The major problem in Truncus is that the lungs are flooded with blood and the heart muscle is overloaded

Question 3

TA symptoms

Answer 3

Bluish skin (cyanosis)
Delayed growth or growth failure
Fatigue
Lethargy
Poor feeding
Rapid breathing (tachypnea)
Shortness of breath (dyspnea)
Widening of the finger tips (clubbing)

Question 4

TA - with a homograft conduit what may be a prob

Answer 4

the conduit may get kinked when closing the sternum due to myocardial edema so you may not be able to close the chest
also the conduit may grow onto the sternum and when cutting the chest open you need to decompress the heart first so first go on bypass fem-fem

Question 5

TA embryology - what is it the result of?

Answer 5

The anomaly is thought to result from
failed septation of the embryonic truncus arteriosus.
Aortopulmonary and interventricular defects are believed to represent an abnormality of conotruncal septation.
Because the common trunk originates from both the LV and RV, and PA’s arise directly from the common trunk, a PDA is not required to support the fetal circulation

Question 6

The truncus arteriosus and bulbus cordis are divided by what?

Answer 6

the aortico-pulmonary septum.

Question 7

The truncus arteriosus gives rise to

Answer 7

the ascending aorta and the pulmonary trunk.

Question 8

The bulbus cordis gives rise to

Answer 8

the smooth parts (outflow tract) of the LV and RV

Question 9

TA Type I:

Answer 9

truncus-> one pulmonary artery -> two lateral pulmonary arteries

Question 10

TA Type II:

Answer 10

truncus-> two posterior/ posteriolateral pulmonary arteries

Question 11

TA Type III:

Answer 11

truncus-> two lateral pulmonary arteries

Question 12

Truncus Arteriosus type I

Answer 12

characterized by origin of a single pulmonary trunk from the left lateral aspect of the common trunk, with branching of the left and right pulmonary arteries from the pulmonary trunk.

truncus-> one pulmonary artery-> two lateral pulmonary arteries

Question 13

Truncus Arteriosus type II

Answer 13

is characterized by separate but proximate origins of the left and right pulmonary arterial branches from the posterolateral aspect of the common arterial trunk.

truncus -> two posterior/ posteriolateral pulmonary arteries

Question 14

Truncus Arteriosus type III

Answer 14

Branch pulmonary arteries originate independently from the common arterial trunk or aortic arch, (most often from the left and right lateral aspects of the trunk).

This occasionally occurs with origin of one pulmonary artery from the underside of the aortic arch, usually from a ductus arteriosus.

truncus -> two lateral pulmonary arteries

Question 15

Truncus Arteriosus mixing in the heart??

Answer 15

Since the truncal valve is above the VSD, blood is pumped from both the RV and LV to the lungs and to the body, (mixing is occurring).

Question 16

Truncus Arteriosus why is there increase BF to lungs?

Answer 16

Pulmonary resistance (PVR) is lower than systemic resistance (SVR). Therefore, there is usually increased blood flow to the lungs. This increased PBF can lead to CHF.

Because the lung arteries are connected to the high pressure pumping chambers (LV/RV) there is pulmonary hypertension. If the lungs are exposed to both high pressure and extra blood flow for an extended time (months to years), irreversible pulmonary hypertension can occur.

Question 17

Palliative Surgery for Truncus Arteriosus?

Answer 17

PA Banding -involves banding the pulmonary arteries coming off the truncus (reduces pulmonary blood flow)

Question 18

PA banding of TA - how is surgery done?

Answer 18

The left anterior thoracotomy approach through the second or third intercostal space gives excellent exposure for isolated pulmonary artery banding.

Extracardiacprocedure –no CPB

a fix, not a cure.

Question 19

Treatment of choice for Truncus Arteriosus?

Answer 19

Complete repair is the treatment of choice and usually a modification of a Rastelli procedure. A Rastelli procedure connects the RV-PA. This tube is usually a homograft, (made from human cadaver tissue).

During the Rastelli procedure, the VSD is closed with a
Gore-Tex patch so that the aorta arises solely from the left ventricle.

Question 20

Surgical Repair for TA – 4 steps?

Answer 20

A Origin of truncus arteriosus PA’s are excised and the
truncus defect closed with direct suture. An RV ventriculotomy is made.
B Ventricular septal defect (VSD) is closed with a prosthetic patch.
C Placement of a valved conduit into the pulmonary arteries.
D Proximal end of conduit is anastomosed to the RV.

Question 21

TA complete repair - CPB considerations?
incision?
cannulation? 
temp? 
CPG?

Answer 21

Incision: Median sternotomy
Arterial: Aortic
Venous: Single atrial cannula
Aortic XC: moderate length
Hypothermia: Mild to Moderate period DHCA
Cardioplegia: Antegrade, possibly retrograde, Be prepared for retrograde CP (monitor CVP should be 30-40 mmhg)

Question 22

TA complete repair, post-op considerations?

Answer 22

Delayed sternal closure is often required following repair of truncus arteriosus.
Marked improvement in blood gases (post-op vs. pre-op)
At some point changing of the RV-PA Conduit would be done as a redo Rastelli (Maybe twice ? )