This document provides an overview of the classification, pathophysiology, preoperative evaluation, and anesthetic management considerations for patients undergoing surgery with congenital heart defects such as atrial septal defects (ASD) and ventricular septal defects (VSD). It discusses the pathophysiology of left-to-right and right-to-left shunting, preoperative assessment including history, examination, investigations, and risk factors. It also outlines goals and techniques for anesthesia including bubble avoidance, optimizing oxygen delivery and ventilation, and avoiding hypovolemia and increases in left-to-right shunting. Specific considerations for inhalational and intravenous induction agents, central neuraxial blockade, pregnancy, and Eisenmenger

1. Classification of CHD ASD & VSD: Pathophysiology, preopevaluation, Anaesthetic management for incidental surgery Dr.Nishad.P.K AIIMS, NewDelhi

2. Classification of CHD Left to right shunts Right to left shunts(cyanotic lesions) Obstructive lesions Single ventricle Others : Vascular rings, Venous anomalies, Arteriovenous fistulae

3. Left to right shunts Atrial level : ASD, PAPVC Ventricular level : VSD Endocardial cushion defects Great artery level : PDA, AP window, Coronary level : ALCAPA, coronary fistula

4. Right to left shunts With pulm. stenosis TOF TA Ebstein’s anomaly With pulm HTN Eisenmenger’s syndrome With ↑ PBF TGA TAPVC SV W/O obst: to PBF PTA TA DORV

5. Obstructive lesions Left heart Obstructed veins Mitral stenosis Aortic stenosis Coarctation Interrupted aortic arch Hypoplastic left heart syndrome Right heart Pulmonary stenosis / atresia Tricuspid stenosis Hypoplastic right heart

6. ASD Opening in the interatrial septum i: 1 in 1500 live births 6- 10% of CHD. 30% of CHD in adults Females >males Types : Ostium secondum(75%) Ostium primum(15%) Sinus venosis(10%) Patent foramen ovale(5%) Coronary sinus(rare) VSD Most common CHD(20%) i: 2.6 – 5.7 per 1000 live births 10% of adult CHD Types : Subpulmonary (5 – 7 %) , ass. With aortic valve insufficiency Perimembranous (80% ) , ass with tricuspid valve abnormality AV canal (5 – 8 %) Muscular (5 – 20%) Small, medium, large

8. Pathophysiology

9. Pathophysiology: ASD L->R shunt RAV ↑ RVEDV ↑ PBF ↑ PVR ↑ ` RVP ↑ RVH The L->R flow is typical biphasic – one peak flow occurs during late systole & early diastole (v wave), other during late diastole (a wave) R->L shunt component sudden intrathoracic pressure drops as in spontaneous ventilation, relaxing phase of valsalva maneuver with ↑ in RV afterload (IPPV, PEEP>15cm H2O) Natural history

10. Pathophysiology :VSD During systole. Bypasses the RV cavity. L->R shunt ↑in PBF,LAV,LVEDV LVH Cause : CHF at 6-10 wks rec: RTI pulm HTN Eisenmenger’s syndrome Adaptive mechanisms : ↑SV,contractility,HR& myocardial mass

11. Features of VSD based on size ↓ Yes Yes ↑ + None L->R R->L Large None No Yes ↑ + None R->L Large with ↑ PVR PSM Yes Mild mild↑ ± 20mmHg L->R Med PSM Yes No N ─ High L->R Small Murmur LVH RVH RVP ↑ PVR Gradient Shunt

12. Pathophysiologic classification of shunts SmallASD, VSD Relatively fixed,low to moderate volume,ind of PVR & SVR Small,restricted Restrictive Large ASD,VSD Variable,depends on PVR& SVR Large & unretsricted;pressures approx equal Dependent Examples Degree of shunt Features Type of shunt

13. Pre op evaluation 1.Review underlying anatomy & physiology of cardiac lesion Previous cardiac surgeries – palliative vs. reparative Evaluate existing residua or sequelae 2.Assess other pre existing or congenital anomalies Extra cardiac malformation in 20-45% Known chromosomal anomaly in 5 - 10% ASD -- Trisomy 21,18,13,XXXY,Del 4p,5p,CHARGE,Fetal Hydantoin Syndrome,Fetal alcohol syndrome,Holt Oram ,Treacher collins,Noonan’s VSD -- Trisomy 21,18,13,XXXY,Del 4p,5p,CHARGE,Fetal Hydantoin Syndrome,Fetal alcohol syndrome, Del 10q, 13q, 18q, Fetal valproate syndrome, Elis van creveld syndrome, Apert…

14. Pre op evaluation(contd..) Examination General Airway Cardiac Respiratory 3.History functional status CHF Cyanotic spells Recent RTI Coexisting illness:GERD, reactive airway d/s, seizure d/r

15. Pre op evaluation (contd..) 4.Investigations Hemogram S.electrolytes ECG CXR ECHO Cardiac cath.

16. ECG

17. CXR ASD VSD

18. Pre op evaluation(contd..) 5.Review information from last cardiological examination Recent cardiac cath, echo Functional status 6.Assess risk factors Pulmonary HTN Cyanosis Reoperation Arrhythmias Vent dysfunction 7.Review changes since last cardiac examination History & physical examination Lab data Current medication

19. Pre op evaluation(contd..) 8. Review proposed surgical procedure Elective vs. emergent Expected length& invasiveness 9. Plan treatment of potential complications Dysrhythmias Pulmonary hypertension Ventricular dysfunction 10. Plan post op care Monitoring Pain management Cardiology follow up 11. Discuss anaesthetic plan & risk with patient/parent

20. Preop preparation Fasting Guidelines: Avoid dehydration/hypovolemia Premedication: Benefits: Anxiolysis ↑ cooperation ↓ separation anxiety ↓ cardiovascular liability Detrimental effects: Hypoventilation Hypotension Pain on administration

21. IE Prophylaxis (AHA 2007 guidelines) Unrepaired cynotic CHD (Eisenmenger’s) Completely repaired CHD with prosthetic material or device during 1 st 6 months Repaired CHD with residual defects at/near the patch or device which inhibit endotheliazation Previous IE

22. IE PROPHYLAXIS IS NO LONGER RECOMMENDED FOR ANY OTHER FORM OF CHD Procedures All dental procedures that involve manipulation of gingival tissue,or periapical region of teeth or perforation of oral mucosa Procedures on RT, infected skin, skin structures, MST NOT recommended for GI or GU tract procedures IE Prophylaxis (contd…)

23. IE Prophylaxis (contd…)

24. Monitoring Pulse Oximetry NIBP ECG Capnography Urine Output Temperature CVP IBP TEE

25. Anaesthetic goals Bubble avoidance Optimizing O2 delivery & ventilatory function Avoid hypovolemia ↓ L->R shunt

26. Bubble Avoidance: Remove all bubbles from iv tubing Connect iv tubing to the venous cannula while there is free flow of iv fluid and blood Eject small amount of solution from syringe to clear air from needle to hub before injection Aspirate injection port of 3 way before injection to clear air Hold the syringe upright to keep bubbles at the plunger end Do not inject the last ml from the syringe Do not leave a central line open to air

28. Hypovolemia is poorly tolerated in these patients. The low resistance pulmonary circulation tends to steal volume from the high resistance systemic circulation. This is further increased by the systemic arterial vasoconstriction of hypovolemia

29. Cardiac Grid - ASD N N ↓ N to ↑ ↑ Res L->R shunt N N N N N Repaired N N ↓ N to ↑ ↑ Unrepaired Contractility HR SVR PVR Preload

30. Cardiac Grid - VSD N N N N ↑ Repaired N N ↓ N to ↑ ↑ Unrepaired Contractilit y HR SVR PVR Preload

32. Controlled ventilation is optimal as : Many patients with CHD cannot tolerate the high conc. Of inhalation agents required during SV Appropriate ventilation helps prevent atelectasis & hypercarbia Ventilation is a compromise between active hyperventilation & preservation of mean intrathoracic pressure Ideal tidal volume corresponds to FRC to obtain PaCO2 & lowest mean intrathoracic pressure

33. At low Tidal volume: hypercarbia & atelectasis ↑ PVR At high tidal volume: large extra alveolar vesels are much compressed& ↑ PVR

34. Inhalation : In L->R shunts with ↑ pulmonary blood flow, speed of inhalation induction is unchanged. We found more episodes of severe hypotension & an increased incidence of bradycardia and emergent drug use in the patients that received halothane than in patients who received sevoflurane (Anesth Analg 2001;92:1152–8) Intravenous: Time to appear in systemic circulation is unchanged though peak plasma conc. are lower & effect is prolonged Thiopentone:↓ SVR, well tolerated in normovolemic, stable CHD Propofol: Significant ↓ in SVR & MAP Ketamine: ↑ SVR, ↑ L->R shunt Etomidate: minimal cardiovascular effect Induction:

35. Central Neuraxial Blockade Merit: ↓ SVR Demerits : Incremental IPPV represents a weak ↑ compared with already elevated pulmonary pressure & RV well adapted to ↑ afterload IPPV allows hypervent & ↓ PVR VD due to sudden profound fall in SVR can reverse shunt

36. Pregnancy & L -> R shunts Modest L->R shunts are well tolerated during pregnancy Anaesthetic management should pay attention to: Care to avoid bubble infusion LOR to saline rather than air during epidural catheterization Early administration of labor analgesia as pain ↑ SVR & catecholamine release worsening L->R shunt Slow onset of epidural anaesthesia is preferred Monitoring of SpO2 & provision of supplementary O2

37. Child with incidental murmer History, cardiac examination and ECG Echo and cardiac opinion prior to sx if: Younger than 1 yr Pathological murmurs Cardiac signs or symptoms Evidence of LVH or RVH Criteria for pathological murmurs All diastolic murmurs All PSM Late systolic Very loud Continuous murmurs With cardiac signs or symptoms

38. Eisenmenger’s syndrome Prevent further increase in Rt to Lt shunt Maintain COP Prevent arrhythmias Avoid hypovolemia,  PVR,  SVR Marked increase in SVR should also be avoided as excessive systemic vasoconstriction can precipitate acute LVH Prevent thrombosis and optimize coagulation IE prophylaxis

39. Much more to come Are we all still awake?

40. THANK YOU