Single Ventricle: congenital cardiac malformations that lack two completely well developed ventricles, and in which functionally there is only a single ventricular chamber that supports both pulmonary and systemic circulations

Classifications of Single ventricle: Hearts with common inlet atrioventricular connection [Double-

inlet RV/ Double-inlet LV] Hearts with absence of one atrioventricular connection [Tricuspid

atresia / Mitral atresia] Hearts with common atrioventricular valve and only one well-

developed ventricle [unbalanced common atrioventricular canal defect]

Hearts with only one fully developed ventricle Hypoplastic left heart syndrome

Double-outlet right ventricle and a ventricular septal defect remote from semilunar valves Other rare forms of univentricular hearts

1.Inadequate pulmonary circulation (or ductal dependent)2.Excessive pulmonary circulation without systemic obstruction3. Excessive pulmonary circulation with systemic obstruction 4. Balanced pulmonary flow

Medical management: (temporary palliation) Prostaglandin E1 Restoraration of normal acid base status Maintain End organ perfusion & function

Aim of surgical intervention: to improve the natural history by balancing blood flow between the pulmonary and systemic circulations and ultimately separating these two circulations.

In patients with Pulmonary outflow obstruction: pulmonary atresia/stenosis Consistently SaO2 <75~80% Systemic to pulmonary

arterial shunt: modified B-T shunt: graft from subclavian A to PA

To improve SaO2

In patients with excessive pulmonary blood flow: SaO2> 85% strongly suggest excessive pulmonary blood flow Volume overload to the single ventricle: cause CHF Pressure overload to the pulmonary arteriole tree: cause

pulmonary vascular disease Tx: PA banding!

Exclude obstruction of systemic outflow!

SaO2 80~85%

In patients with excessive pulmonary blood flow with systemic obstruction-

DKS procedure (Norwood + BT shunt)

One of the following conditions: Mean PA pressure up to 20mmHg 2 PVR ≦ ＜ 4 Wood units but reactive to vasodilators Surgically repairable PA hypoplasia or discrete stenosis

present McGoon ratio is 2.0 and repairable LVED volume is 2SD above the mean[compared with

normal structural heart] Target SpO2: 78~85%

Bidirectional cavopulmonary shunt as a staging

Maneuver, usually combined with repair of associated lesion leading to poor outcome of Fontan’s operation, including pulmonary arterial stenosis, atrioventricular valve regurgitation, and systemic outflow tract obstruction.

To reduce the volume load on single ventricle & maintain a viable Spo2.

So to preserve ventricular function for the subsequent Fontan

COMMENTSCOMMENTS

End to side connection between the cranial end of SVC & right pulmonary artery

Ligation of of azygous If b/l SVC, both should be connected to respected Pas The cavopulmonary shunt increases effective pulmonary

blood flow without volume-loading the ventricle. Systemic venous collateralization may worsen hypoxemia by

reducing the effective pulmonary blood flow There are concerns about the growth of the pulmonary

arteries . Pulmonary arteriovenous fistulae may be a universal

consequence of the bidirectional cavopulmonary shunt

Contd.Contd.

promotes regression of left ventricular mass in younger children.

Improvement in the degree of atrioventricular valve regurgitation.

Intra-atrial baffle / Lateral tunnel method Extra-cardiac conduit method

To drain all systemic veins directly into PA Preserve the Functioning single ventricle for systemic circulation

Goal: BEFORE proceeding to the Fontan circulation, appropriately regulating pulmonary blood flow since newborn period

(1) Improve clinical symptoms: cyanosis, CHF (2) Provide optimal pulmonary artery architecture and low

pulmonary vascular resistance (3) Preserve systolic and diastolic ventricular function (4) Preserve atrio-ventricular valve function (5) Relieve systemic ventricular outflow tract obstruction (6) Provide anatomic setup for a definitive Fontan repair

Ideal saturation: SpO2 80%

Proper Patient Sellection!!!!!!

Graham and Johns pointed out that theGraham and Johns pointed out that thefollowing issues or criteria were not includedfollowing issues or criteria were not included

Diastolic dysfunction, Ventricular hypertrophy, Systemic outflow tract obstruction, Right ventricular type of single ventricle, Extensive systemic aortopulmonary collaterals.

NECESSARY CRITERIANECESSARY CRITERIA

1. Undistorted pulmonary artery anatomy;

2. Low pulmonary vascular resistance;

3. Low ventricular end diastolic pressure;

4. Absence of obstruction to systemic outflow; and

5. Preservation of systemic atrioventricular valve function.

METHODMETHOD

The lateral tunnel technique involves placement of a baffle along the lateral aspect of the right atrium, which conveys IVC blood to SVC orifice.

4 mm fenestration is made in the medial aspect of baffle to prevent the systemic venous pressure risisng to intolerable limit.

Large ASD is created to prevent any restriction of flow between atria.

Allows to preserve systemic cardiac output at the expense of some reduction in arterial saturation.

Lower operative mortality &p/o pleural effusion.

Post operative managementPost operative management Minimize PVR Monitor systemic & pulmonary pressure & indicators of good cardiac

output as strength of pulse, urine output, BP, CRT. Systemic venous hypertension lead to reflex arterial constriction lead

to increased afterload may impair cardiac output- milrinone, nitroprusside

Arrhythmias- atrial pacing lowers atrial filling pressure & augments cardiac output

Pleural effusion & ascites- complete drainage

Early mortality: 7.7% Late mortality:

Survival 93% at 5years, 91% at 10 years Most common causes of death

Thromboembolism: intra-cardiac thrombus, lack of Aspirin / Warfarin

Heart failure: morphological RV, high RA pressure, protein-losing enteropathy

Sudden death: cardiac arrhythmias [within fist 5 years after Fontan surgery]

Complications: Early complications: pleural effusion, pericardial

effusion, sternal wound infection, arrhythmia, stroke……

Late complications: atrial arrhythmia, ventricular dysfunction, protein-losing enteropathy, thromboembolic events

Atrial arrhythmia Major risk factor for morbidity and functional

decline after the Fontan procedure Incidence: 10~40% Most common: Sinus node dysfunction!! [sinus

node injury while REDO or disturbance of its blood supply]

Cause: RA dilation, RA incision Tx: anti-coagulant if refractory

Protein-losing enteropathy Very poor prognosis!!! : 5-yr survival 59%, 10-yr

survival <20% Incidence: 3.8%~10% Lymphatic drainage dysfunction Tx: anticongestive therapy, steroid, heparin, atrial

fenestration, heart transplantation!

Ventricular dysfunction/heart dailure: 8.3% Preload reduced to 50~70% of normal for BSA Ventricle: from volume overload and overstretched

to severely undeloaded→”Disuse hypofunction”: remodelling, reduced

compliance, poor ventricular filling, continuous declining cardiac output

Tx: heart transplantation! [Late take down or fenestration before heart transplantation]

Right atriomegaly and hepatic dysfunction Dilatation of the coronary sinus Pulmonary arteriovenous malformations Myocardial dysfunction and failure Ventricular outflow obstruction Obstruction of pulmonary veins Recanalization of ligated main pulmonary trunk Systemic venous collateralisation Bronchitis Pancreatitis WPW syndrome