202409271935
Status:
Tags: CHD
Transposition of great arteries
most common cyanotic cardiac lesion in newborns, accounting for 5-10% of all CHD.
Anatomy & physiology
Discordant ventriculoarterial connection
AV valve follows the ventricle
d-TGA
d = dextro looping pattern
- situs solitus of atria
- concordant AV connection
- a/w VSD in 40%
- LVOTO in 5-10%
In contrast to the normal subpulmonary infundibulum, there is a subaortic conus, and fibrous continuity is present between the pulmonary and mitral valves, unlike in the normal heart where an aortic-mitral curtain is found.
The term ‘simple’ transposition refers to the malformation in which the ventricular septum is intact or nearly intact in the presence of a small VSD and the LVOT is not obstructed.
Other structural anomalies/variants that are associated with TGA include pulmonary valve stenosis, obstruction to the RV outflow tract (RVOT), aortic stenosis, aortic arch obstruction, atrioventricular valve abnormalities, variations in coronary artery pattern, persistent left superior vena cava, and juxtaposed atrial appendages.
Physiology = parallel circulation
incompatible w/ life unless intercirculatory shunting exists (e.g. PFO, ductus arteriosus)
similar physiology to double outlet RV w/ subpulmonary VSD (Taussig-Bing malformation)
temporising measure:
- balloon atrial septostomy
- prostaglandin E1 → maintaing ductal patency
ccTGA = L-TGA
"double discordance":
- AV discordance
- VA discordance
Ebstein's like valve
predisposition to heart block & arrhythmia e.g. WPW
Dextro vs meso vs levocardia
presentation: RV failure
regurgitation of systemic TV
establish situs
Hint in Echo
systemic RV hypertrophied & many trabeculations
systemic ventricle no papillary muscles but moderator band present
systemic AV valve trileaflet & attached closer to apex
Atrial switch operation
The atrial baffle procedures (Mustard and Senning operations) reroute the systemic venous return to the LV and the pulmonary venous return to the RV, thus allowing for physiologic correction in transposition
Most adult patients are likely to have undergone this type of repair. Long-term problems related to these interventions led to the evolution of the surgical approach for this lesion
Arterial switch operation
The arterial switch operation (ASO) is the current preferred surgical strategy for patients with TGA.
This single-stage procedure is performed in the first few weeks of life and involves
- transecting both arterial roots above their respective sinuses,
- switching the great arteries to restore the normal ventriculoarterial connections,
- translocating the coronary vessels to the ‘neoaortic’ root.
Outcomes after the operation are generally excellent.
Rastelli operation
The concomitant presence of a VSD and pulmonary stenosis/LVOT obstruction in the setting of TGA requires alternative surgical management strategies
Rastelli procedure involves creating an intracardiac patch or tunnel that reroutes the LV output through the aorta while closing the interventricular communication, and placing an extracardiac tube or conduit between the RV and PA
Echo
post-op surveillance
| Arterial Switch Operation | Atrial Switch Operation | Interventions for Complex TGA |
|---|---|---|
| - Supravalvar and branch PA stenosis (most common problem) - Neoaortic root dilation - Neoaortic regurgitation - Residual shunts - Residual aortic arch obstruction - Coronary issues resulting in ischemia, LV dilation, and functional impairment (global/regional wall motion abnormalities) - Pulmonary hypertension (assessed by parameters such as TR or PR jet velocity, configuration of IVS) - Atrial baffle leaks (left-to-right shunts) |
- Atrial baffle stenosis: systemic venous baffle (superior limb most common site of obstruction) and pulmonary venous baffle - TV regurgitation (systemic AV valve) - Systemic RV dysfunction - Outflow tract obstruction - Pulmonary hypertension (assessed by parameters such as MR jet velocity and configuration of IVS; as PA pressure increases septum bows towards systemic RV) - Conduit dysfunction stenosis/regurgitation (depending on type of RVOT reconstruction) |
- RVOT obstruction/PA stenosis - Residual shunts (particularly at ventricular level) - LVOT obstruction (baffle obstruction after Rastelli operation) - Coronary issues (related to distortion of vessels or if reimplantation required in Nikaidoh operation) |
Post-atrial switch
assess venous baffles for obstruction or leaks
- baffle flow (by doppler)
- should be pulsatile
- always return to baseline
- often <1.5m/s
identification of intracardiac shunting
Post-ASO:
AV & semilunar valves for regurg
interrogation of outflow tracts (aortic & PA anastomoses) & branch PAs to exclude obstruction
residual shunts
References
Echocardiographic Evaluation of Transposition of the Great Arteries
Medmastery CHD Chapter 9
123sonography ACHD - ccTGA