10 – Atrial septal defects Zeeshan.pptx

Atrial septal defects

1. 10 – Atrial septal defect Dr. Zeeshan Abdul Nasir PGY3 Cardiac surgery MTI - PIC

2. Definition Embryology Surgical anatomy of Right Atrium Classification Pathophysiology Clinical manifestation Physical examination Investigations Management

3. Definition Communication between the atria resulting from a deficiency of tissue in the septum causing a left to right flow. Acyanotic congenital heart disease. Severity depends on: Size of defect Size of shunt Resulting from asymptomatic to right sided overload, PAH.

4. Embryology Primitive atrium – partitioned into right and left atria by growth of the Septum primum – Thin crescent shaped membrane that grows from the roof of the primitive atrium toward the endocardial cushion. Foramen primum – composed of the free edge of the septum primum and the endocardial cushions

5. Fenestrations develop in the septum primum – coalesce to form the Ostium secundum . Septum primum fuses with the endocardial cushions . Failure of this fusion  Primum ASD Ostium secundum maintains a right-to-left atrial flow – fetal circulation.

6. Septum secundum – forms to the right of the septum primum, growing toward the endocardial cushions and usually closing the Ostium secundum. Failure to close  Secundum ASD

7. Surgical anatomy of the Right atrium Crista terminalis Fossa ovalis Coronary sinus Thebesian valve (Coronary sinus) Eustachian valve (IVC) Tendon of Todaro AV node Bundle of his SA node

8. Classification According to location Secundum ASD Primum ASD Sinus venosus ASD SVC type IVC type Coronary sinus ASD

9. According to size In younger children: Small defect < 3 mm Mod defect 3 – 8 mm Large defect > 8 mm In older children: Small < 6 mm Mod 6 – 12 mm Large > 12 mm

10. Secundum ASDs MC type – 70 to 75 % of ASDs Location – Midportion of the atrial septum, within or including the fossa ovalis Single or multiple

11. Primum ASDs 15 – 20 % Part of the spectrum of Atrioventricular septal defects (AV Canal defects or endocardial cushion defects). Occur in the inferior – anterior portion of the atrial septum. Cleft in the anterior leaflet of the mitral valve (mitral valve cleft) – MR Mostly associated with Down’s syndrome.

12. Sinus venosus ASD 5 – 10 % Involves the portion of the atrial wall derived from the sinus venosus – no direct communication between the right and left atria Typically at the orifice of SVC at the junction of the RA Less frequently in the region of the IVC Associated with partial anomalous pulmonary venous drainage (PAPVD) – pulmonary drainage to RA instead of LA.

13. Coronary sinus ASD Defect in the roof of the coronary sinus  direct communication with the LA. Rare Usually associated with complex CHDs. Divided into CSASD with LSVC CSASD without LSVC

14. Pathophysiology Moderate – to – large defects – Shunt of oxygenated blood flows from L  R atrium Volume overload and dilation of the RA and RV Tricuspid and pulmonary annulus may dilate and become incompetent Inc flow into the lungs  Irreversible pulmonary vascular injury (Endothelial dysfunction and vascular remodelling ) – Inc in PVR  inverted shunt: R  L Eisenmenger syndrome (Cyanosis)

15. Clinical manifestation Asymptomatic Infants Recurrent chest infections FTT Older children Mild fatigue Dyspnea that may worsen with age Cyanosis

16. Physical examination Precordium Inspection Precordial bulge Palpation Prominent right ventricular heave felt along the lower left sternal border and the subcostal area Auscultation Wide, fixed splitting of the S2 ESM – Left 2 nd & 3 rd sternal border

17. Investigations Non – invasive Chest X-Ray ECG Echocardiography Invasive Cardiac catheterization

18. Chest X-ray Small shunt across the ASD – Normal CXR Large shunt – Cardiomegaly (RA and RV enlargement) Increased pulmonary vascular markings extending to the periphery

19. ECG Prolonged PR interval – due to enlargement of RA – 1 st degree heart block Crochetage sign – notched R waves in inferior leads

20. Echo Diagnostic

21. Cardiac catheterization In whom pulmonary vascular resistance may be a concern. Diagnosing associated lesions i.e. PAPVD MS Direct measurement of intracardiac and pulmonary artery pressure PVR can be calculated

22. Management Medical therapy Interventional therapy Surgical therapy

23. Spontaneous closure In patients with an ASD < 3 mm in size diagnosed before 3 months of age – 100% of patients at 1 ½ year of age. 80% in b/w 3 – 8 mm. Spontaneous closure uncommon after 1 st year.

24. Medical management Aim to reduce volume overload and to strengthen functions of heart muscles. Symptomatic children: Diuretics – relieve ventricular overload, peripheral and pulmonary congestion Rate control and anticoagulation – Afib Anti hypertensives i.e. Captopril, to reduce afterload

25. Interventional therapy Trans-catheter device closure of ASD Indicated in: Secundum ASD with Qp:Qs ≥ 1.5:1 5 mm or more but less than 32 mm A significant L  R shunt with clinical evidence of RV volume overload There must be enough rim (~4 mm) of septal tissue around the defect for appropriate placement of the device

26. Contra-indication: Resting pulmonary HTN Failed attempted device closure No sufficient rim to engage the device Sinus venosus defect – device closure would threaten obstruction of pulmonary veins, IVC and SVC Recent infection or sepsis/Bleeding disorders Pregnancy Intracardiac thrombi

27. Devices available are: Amplatzer septal occlude Rashkind ASD occlude Cardioseal device HELEX PFOStar

28. Post device closure follow up Aspirin 5 mg/kg/day for 6 months F/U echo for: Device position Residual shunting Complications F/U echo at 24 hours 1 month 6 months 1 year

29. Complications of device closure Device misalignment/embolization Device erosion of atrial wall or aorta Device impingement on adjacent structures i.e. AV valve, Coronary sinus, SVC Infection including endocarditis Thromboembolic complications Valvular regurgitation Residual shunt

30. Surgical closure Indications: When device closure is not considered appropriate CCF in infancy not responding to medical therapy Sinus venosus defect Secundum ASD + unfavorable anatomy not amenable to p/c closure; ASD Diameter > 35 mm Inadequate septal rims to permit device deployment Close proximity to AV valve, coronary sinus, or venae cavae Timing – Usually delayed until the patient is 2 – 4 years old ( spont closure !)

31. Set up Standard invasive monitoring and general anesthesia. Median sternotomy, heparinization at 300U/kg. Standard aorto- bicaval venous cannulation, and patient cooled to 30–32 o C. Antegrade cardioplegia.

32. Secundum ASD Primary closure Because of the oval shape of most secundum defects, 80 per cent can be closed by the primary suture technique. A double layer of polypropylene is begun at the inferior limit of the defect, as this margin is typically most difficult to define. Before complete closure of the defect, entrapped air should be evacuated from the left atrium.

33. Patch closure If the defect is large or rounder in shape, patch closure should be performed to avoid closure under tension and distortion of atrial anatomy. A patch of autologous pericardium that is slightly smaller than the relaxed size of the defect can be used, again beginning the suture line inferiorly. Polytetrafluoroethylene, Dacron, and bovine pericardium are also suitable patch materials.

34. Sinus venosus defect The ASD is generally more superior and posterior than the typical secundum ASD. The right upper pulmonary veins typically drain into the junction of the SVC and right atrium. Occasionally, multiple veins drain the right upper lobe and may enter the SVC some distance from its atrial junction. Careful circumferential dissection of the SVC allows identification of these anomalous venous connections for cannulation site selection and planning of the repair. Injury to the right phrenic nerve must be avoided during dissection of the lateral aspect of the SVC.

35. Baffle repair If the pulmonary veins drain to the cavoatrial junction area, baffle repair of the defect using a pericardial patch is performed.

36. P atch is sutured from the lower edge of the septal defect, transitioning up and around the superior edge of the highest pulmonary vein to direct the flow of pulmonary venous blood through the septal defect to the left atrium. The patch should be slightly redundant to avoid obstructing this pathway, especially when it is extended up the vena cava for more than a few millimeters

37. Warden repair If pulmonary veins enter some distance up the SVC or if the right SVC is unusually small as seen in the presence of a persistent left SVC, the so-called Warden repair is performed, directing the lower SVC flow through the septal defect, with translocation of the upper SVC to the right atrial appendage.

38. Thank you