PRINCIPLES OF SURGERY IN COMPLEX CONGENITAL CYANOTIC HEART DISEASE

PRINCIPLES OF SURGERY IN COMPLEX CONGENITAL CYANOTIC HEART DISEASE

Dr Vinod Normal human circulation needs two ventricles and two unobstructed circulations. Most cyanotic children coming for surgical intervention have two ventricles still a good number will have only one functional ventricle (Single Ventricle) A few of them have only one circulation connected to the heart(Single Circulation) while the other circulation is supplied through the duct (duct dependent circulation)The type of repair depends on the availability of ventricles and connections of both circulations to the heart. When there are two balanced ventricles and normally connected two circulations a biventricular repair is possible as in Tetralogy of Fallot, TGA and TAPVC which can give the baby a nearly normal heart for the rest of life.When there is a functional single ventricle with both circulations normally connected the pulmonary circulation is disconnected from the ventricle in stages first the SVC and later the IVC so that the single ventricle needs to support only the systemic circulation offering the child the maximum possible palliation for a longer time. This is the Fontan principleTricuspid Atresia

Definite surgery is Fontan Ideal candidates for a Fontan-type operation are those who have normal LV function and low pulmonary resistanceStaged palliative procedure before FONTAN are aimed at producing ideal candidates for a future Fontan procedure.

1.Normal LV function results from prevention of excessive volume or pressure loading of the LV by a.Preventing excessive volume load by using a relatively small systemic-to-pulmonary shunt (e.g., 3.5 mm for neonates)b.Avoiding ventricular hypertrophy ( e.g, by relieving outflow obstruction). 2. Low pulmonary resistance may result from a.Providing adequate PBF that promotes the growth of PA branches with resulting increase in the cross-sectional area of the vascular bed b.Preventing distortion of the central pulmonary arteries. A shunt operation is preferably done on the right PA, which can be incorporated into the Fontan operation. c.Protecting the pulmonary vascular bed from overflow or pressure overload by PA band when PBF is increasedStage I. Blalock-Taussig shunt Damus-Kaye-Stansel operationPA banding is indicated for infants with too much PBF

1. Blalock-Taussig shunt. TA with decreased PBF need the BT shunt This procedure results in the volume load on the LV because the LV supplies blood to both the systemic and pulmonary circulations. The shunt should be relatively small (e.g., 3.5 mm) and should not be left alone too long.2. Damus-Kaye-Stansel and shunt operation (TA+TGA+RESTRICTIVE VSD) The main PA is transected and the distal PA is sewn over. The proximal PA is connected end to side to the ascending aorta. A systemic-to-PA shunt is created to supply blood to the lungs. This procedure also results in volume overload to the LV and a stage II operation should be performed as early as possible. 3. Pulmonary artery banding. PA banding protects the pulmonary vasculature from developing pulmonary hypertension, and it may be performed at any age with a mortality rate of less than 5%. Stage II.

1. Bidirectional Glenn operation (BDG). An end-to-side SVC-to-RPA shunt ( bidirectional superior cavopulmonary shunt) is performed by 2.5 to 3 months of age . By this time the PVR is sufficiently low to allow venous pressure to be the driving force for the pulmonary circulation. For this procedure to be successful, the PVR has to be relatively low because the SVC blood flows passively into the pulmonary arteries. Any previous systemic-to-PA shunt is taken down at the time of the procedure. This procedure increases oxygen saturation which averages 85% without adding volume work to the LV2. The hemi-Fontan operation. An incision is made along the most superior part of the right atrial appendage and is extended into the SVC. A connection is made between this opening and the lower margin of the central portion of the PA. An intra-atrial baffle is placed to direct blood to the pulmonary arteries. The Blalock-Taussig shunt is taken down and the native pulmonary valve is oversewn.

Stage IIIA modified Fontan operation is the definitive procedure for patients with tricuspid atresia.Directing the entire systemic venous blood to the pulmonary arteries without an intervening pumping chamber. The Fontan operation is usually completed when the child is around 2 years of age.

The following are risk factors for the Fontan operation: The presence of two or more of these risk factors constitutes a high-risk situation. 1.High PVR (>2 U/m2) or high mean PA pressure (>18 mm Hg) 2.Distorted PAs secondary to previous shunt operations 3.Poor systolic or diastolic ventricular function with LV end-diastolic pressure greater than 12 mm Hg or an ejection fraction less than 60% 4.AV valve regurgitation

1 Following bidirectional Glenn procedure.

An intra-atrial tubular pathway is created from the orifice of the IVC to the orifice of the SVC termed cavocaval baffle or a lateral tunnel The cardiac end of the SVC is anastomosed to the undersurface of the RPA to complete the operation

An extracardiac conduit may be used to complete the Fontan operation.

use fenestration (4 to 6 mm) in the baffle in high risk patients. Advantages of fenestration decompression of the systemic venous circulation and augmentation of cardiac output in the early postoperative period. Disadvantages include systemic arterial desaturation with possible systemic embolization from the systemic veins and the later need to close the fenestration2.Following the hemi-Fontan operation.

The intra-atrial patch that was used to direct SVC blood to the PAs is excised and a lateral atrial tunnel is constructed directing flow from the IVC to the previously created amalgamation of the SVC with the RPA

Hypoplastic left heart syndrome

Underdevelopment of the left ventricle aorta complex, resulting in critical aortic valve stenosis or aortic valve atresia with an intact ventricular septum is the most recognized form of HLHS

Staged approach

The staged approach ultimately leads a single-ventricle in-series circulation stage 1 : reconstruction of the aortic arch into the right ventricular outflow, separation of branch pulmonary arteries from the right ventricle creation of a restrictive source of pulmonary blood flow from a systemic artery or directly from the single ventricle Stage 2 : unloads the single ventricle by replacing the systemic-to-pulmonary shunt with a superior cavopulmonary anastomosis .

The staged pathway is completed by modifications of a Fontan connection from the inferior vena cava (IVC) to the pulmonary arteries Stage 1:Norwood procedure1) The main PA is divided, the distal stump is closed with a patch, and the ductus arteriosus is ligated. 2) A right-side Gore-Tex shunt is created (with a 4- to 5-mm tube) to provide PBF while preventing CHF and pulmonary hypertension. An RV-to-PA shunt, using PTFE graft, was used (Sano modification). The advantage includes a higher aortic diastolic pressure thus a higher coronary artery perfusing pressure and a lower PA mean pressure. 3) The atrial septum is excised to allow adequate interatrial mixing.

4) Using an aortic or PA allograft, one connects the proximal PA and the hypoplastic ascending aorta and aortic arch.

Stage 2 Bidirectional Glenn procedure and the hemi-Fontan procedure. 1) Cavopulmonary shunt ( the bidirectional Glenn operation) is an end-to-side anastomosis of the SVC to the right PA performed at 3 to 6 months of age in an effort to reduce the volume overload to the systemic RV.

2) The hemi-Fontan operation. This procedure includes augmentation of the central PA without dividing the SVC, while excluding IVC blood from the pulmonary arteriesA modified Fontan operation is performed at 12 to 18 months of age. Five important hemodynamic and anatomic features considered essential to successful Fontan operation are

1 unrestrictive interatrial communication 2 competence of the tricuspid valve 3 unobstructed PAtodescending aorta anastomosis (with pressure gradient less than 25 mm Hg) 4 undistorted PAs and low PVR 5 preservation of RV function.

Significant TR appears to be an important predictor of poor outcome of the Fontan operation. TGA WITH VSD AND SEVERE PSREV procedure (rparation l'tage ventriculaire) First reported by Lecompte, performed for patients with D-TGA with VSD and severe PS. 1 Infundibular resection to enlarge the VSD, 2 Intraventricular baffle to direct LV output to the aorta 3 Aortic transection in order to perform the Lecompte maneuver (by which the right pulmonary artery [RPA] is brought anterior to the ascending aorta) 4 Direct RV-to-PA reconstruction by using an anterior patch . This may require fewer reoperations than the Rastelli procedure

Nikaidoh procedure(D-TGA+VSD+PS)The aortic root is mobilized and translocated to the pulmonary position. The repair consists of the following: 1. Harvesting the aortic root from the RV with attached coronary arteries in the original procedure 2. Relieving the LVOT obstruction by dividing the outlet septum and excising the pulmonary valve 3. Reconstructing the LVOT with posteriorly translocated aortic root and the VSD patch4. Reconstructing the RVOT with a pericardial patch or a homograft

Damus-Kaye-Stansel operation(D-TGA+VSD+SUBAORTIC STENOSIS). The subaortic stenosis is bypassed by connecting the proximal PA trunk to the ascending aorta. The VSD is closed A conduit is placed between the RV and the distal PA

Also done in patients with single ventricle and TGA with an obstructive bulboventricular foramen or DORV with subaortic stenosis

Single ventricle

Most common form is LVGreat arteries are transposedAorta arising from rudimentary RVPS in 50%

The surgical approach for single ventricle

Initial surgical palliative procedures Blalock-Taussig shunt is necessary for cyanotic patients with PS or pulmonary atresia . Shunt to the right PA is preferable because any distortion of the RPA can be incorporated later in the Fontan anastomosis.

In PGE1-dependent neonates, PDA is ligated after placement of the shuntPA banding - infants with CHF and pulmonary edema resulting from increased PBFThe major risk factor is the presence or development of an obstructed bulboventricular foramen. PA banding is performed only when the bulboventricular foramen is normal or unobstructed. If the bulboventricular foramen is too small

1. The Damus-Kaye-Stansel operation is the preferred procedure in the absence of pulmonary or subpulmonary stenosis.PA-to-aorta anastomosis, by transection of the main PA and anastomosis of the proximal PA to the ascending aorta. This is combined with Blalock-Taussig shunt , single ventricle to PA (Sano) shunt , or bidirectional Glenn shunt. A Fontan-type operation can be performed later . 2) Enlargement of the bulboventricular foramen by a transaortic approach This procedure is performed especially when PS is present.

Second-stage surgical palliative procedures a.A bidirectional Glenn operation is carried out between 3 and 6 months before proceeding with the Fontan operation. b. Hemi-Fontan procedure After the second-stage surgical procedure, the child needs to be followed up with attention to the O2 saturation. Initially there is a remarkable improvement in O2 saturation approximately 85% but a gradual deterioration in O2 saturation may occur in the months postoperatively related to the development of pulmonary AV fistula If the child's O2 saturation is 75% or less, one may proceed with the Fontan procedure. Cardiac catheterization is performed by 12 months after the second-stage operation. Ideal candidates should have low mean PA pressure (12C.distorted PAD.low PVR

6.Single ventricle with obstructed bulboventricular foramen stage 1 palliation include all exceptA.DKSB.PA BandingC.BT shuntD.widening of foramen7.Procedure of choice in Taussig Bing anomalyA.VSD to PA tunnel + ASOB.RastelliC.REVD,Nikoidoh8.TGD+VSD+PS treatment includes all exceptA.RastelliB.REVC.NikoidohD.DKS9.DORV Fallot type treatment includes all exceptA.BT shunt as palliative B.RastelliC,REVD.ASO10.Fontan advised in all except A.single ventricle of LV typeB.HLHSC.TAD.DORV