1. Case scenarios Atrial switch Univentricular repair
Dr.Yasser Salem

2. The case of Dr. Marwa Khyry

3. Atrial switch ??

4. Atrio-ventriculo-arterial sequence

5. Atrio-ventriculo-arterial sequence
Concordance
Normal sequence AV & VA
Discordance
Reversed sequence AV & VA
Corrected TGA = AV discordance + VA discordance

6. Atrial switch
Corrected TGA = AV discordance + VA discordance

7. Atrial switch Corrected TGA = AV discordance + VA discordance
Anatomic consideration:
Mustard operation
Senning operation
Corrected TGA = AV discordance + VA discordance

8. Atrial switch RV facing systemic pressure
Functional consideration:
RV facing systemic pressure
Pulmonary hypertension may be present
Baffle may leak or obstruct flow
Suture line near the SA node

9. Mysterious RV

10. AFTERLOAD (MEAN PRESSURE)
Mysterious RV
Positive inotropes CO RV LV
45 mmHg
150 mmHg
AFTERLOAD (MEAN PRESSURE)

12. Mysterious RV

13. Ventricular interdependence
PVA
SVA

14. Ventricular interdependence
PVA
SVA
Atrial interdependence

15. Atrial switch RV facing systemic pressure
Preoperative assesment:
Functional consideration:
RV facing systemic pressure
Pulmonary hypertension may be present
Baffle may leak or obstruct flow
Suture line near the SA node
Evaluation of RV function
Evaluation of pulmonary pressure
Evaluation of baffle status
Evaluation of arrhythmias and pacemaker

17. Single ventricle physiology

19. Mixing lesions
Defects with mixing of oxygenated and deoxygenated blood
Partial desaturation lead to compensatory in red cell mass and increase 2,3 DPG with increase in blood viscosity.

20. Single ventricle physiology

21. Single ventricle physiology
The driving force for Qp is SVC pressure
Qp must pass through two separate and highly regulated vascular beds: cerebral and pulmonary vasculature
Removes the left-to-right shunt and thus the volume load from the single ventricle

23. Single ventricle physiology

24. SVC Pressure Acute rise in SVC pressure
Selection of patients with low PVR minimizes the risk from elevated SVC pressure
Failure to maintain low SVC pressure lead to problems maintaining adequate SaO2
Small veno-venous collateral vessel contribute to arterial desaturation

25. Single ventricle physiology
PSVC
QPA : QSA =
PPA – PPV x +
PLA
QPB : QSB

27. Single ventricle physiology
PSVC -
PLA
QPA : QSA =
PPA – PPV
QPB : QSB
PSVC -
PLA =
QPA : QSA
PPA – PPV x
QPB : QSB
PSVC
QPA : QSA =
PPA – PPV x +
PLA
QPB : QSB

28. Minimize SVC Pressure
Minimize use of positive pressure, including PEEP, following surgery
Allow the end-expiratory lung volume to approximate FRC
Minimal mean airway pressure and early extubation in patient with healthy lungs
Negative-pressure ventilation associated with increased Qp
Higher airway pressure to maintain FRC in pneumonia or ARDS
Aprotinin and modified ultrafiltration:  transpulmonary pressure gradient, less pleural drainage, improved SaO2

29. Vascular Resistance
Qp largely dependent on resistance of 2 highly but differentially regulated vascular beds
Cerebral and pulmonary vasculatures
Opposite responses to changes in CO2, acid-base status, and O2
Qp dependent on venous return through SVC (largely cerebral blood flow)
Hyperventilation following bidirectional cavopulmonary anastomosis impair cerebral blood flow and decrease SaO2
Inhaled NO may be the best treatment for high PVR and low SaO2 after bidirectional cavopulmonary anastomosis

30. Volume Unloading
The right-to-left shunt is eliminated and all Qp is effective pulmonary flow
An acute increase in wall thickness and decrease in cavity dimension has been associated with improved tricuspid valve function
Preload and afterload are both decreased
Change in ventricular geometry may increase risk for systemic outflow obstruction in some

32. Single ventricle physiology
Backward effect
Systemic venous congestion
Need for higher SVC pressure to drive flow in the shunt
Forward effect
Non pulsatile pulmonary flow
Left atrial filling totally dependant on pulmonary flow
Systemic hypotension

33. Single ventricle physiology
Pitfalls
Saturation is not sytemic pressure dependent
Saturation is pulmonary pressure dependent
All circulatory and ventilatory support should be
directed to:
Lower PVR
Higher SVR
Higher Rt filling pressure
(within limits)

34. Single ventricle physiology
Pitfalls
(within limits)
↓PVR
↑SVR
↑CVP