DR.NIHAR MEHTAJASLOK HOSPITAL & RESEARCH CENTRE

FAILING FONTANS

Fontan Circulation

Fontan ProcedureFontan PhysiologyPatient SelectionPost-Fontan ComplicationsFontan OutcomesPost-Fontan PregnancyAnesthesia Implications

Fontan Procedure

It is used to treat complex congenital heart diseases with ONE FUNCTIONAL VENTRICLE that maintains systemic and pulmonary circulations which are not connected in series but in parallel

Bi-ventricular repair is not possible Tricuspid atresia Pulmonary atresia / Severe pulmonic stenosis with intact

IVS Double inlet ventricle Single ventricle Hypoplastic left or hypoplastic right heart Heterotaxy syndromes Severe Ebstein’s anomaly

Fontan Procedure

A single ventricle parallel circuit creates 2 major disadvantages: Systemic arterial DESATURATION at rest Chronic VOLUME OVERLOAD to the ventricle

Without surgical intervention, there is about a 90% mortality before age 1

A completion Fontan is a palliative step in a series of surgeries used to improve oxygenation and cardiac function

The Original Fontans ProcedureATRIOPULMONARY FONTANS

Done for Tricuspid Atresia

End to end shunt from SVC to Right Pulmonary artery

Connection of Left Pulmonary artery to Right atrium diverts IVC blood to LPA

Used 2 homograft valves

INTRA ATRIAL FONTAN – LATERAL TUNNEL

Cavopulmonary Fontan circulation

Intraatrial conduit

IVC to the right pulmonary artery

INTRA ATRIAL FONTANS

EXTRA ATRIAL FONTANS

Extraatrial cavopulmonary Fontan circulation,

Extraatrial conduit

IVC to the right pulmonary artery

EXTRA ATRIAL FONTANS

How to achieve a Fontan Circuit

At BIRTH, it is impossible to create a Fontan circulation: PVR is elevated for several weeks SVC and IVC veins and pulmonary arteries may be too

small

STAGED APPROACH Adapt to changing hemodynamics

How to achieve a Fontan Circuit

Neonatal period (1 month) Improve the limited flow to the lungs – BT SHUNT /

PA BAND

The infant is allowed to grow for several months Pulmonary vasculature will develop more PVR will stabilize

PROBLEMS The heart will be subjected to chronic volume overload / pressure

overload Ventricular function may deteriorate Expect mild progressive desaturation of the infant

How to achieve a Fontan Circuit

BT SHUNT PA BAND

How to achieve a Fontan Circuit

At age 4-12 months The superior vena cava will be connected to the

pulmonary artery (Glenn)

This will decrease the volume load to the heart The patient will remain cyanotic as the desaturated

blood from the IVC is still allowed to flow to the aorta

How to achieve a Fontan Circuit

Single Ventricle – BT Shunt

Single Ventricle – Bidirectional Glenn

http://www.cincinnatichildrens.org/health/heart-encyclopedia/anomalies/sv.htm

How to achieve a Fontan Circuit

At 1-5 years of age The Fontan circuit is completed by connecting

the IVC to the pulmonary artery

Single Ventricle – Bidirectional Glenn

Single Ventricle –Completed Fontan

http://www.cincinnatichildrens.org/health/heart-encyclopedia/anomalies/sv.htm

FONTANS STAGINGSUMMARY

STAGE 1: AT 1 MONTH OF AGE OPTIMISE QP/QS : BT SHUNT / PA BAND

STAGE 2: AT 4-12 MONTHS OPTIMISE VENTRICULAR VOLUME: BD GLENN / HEMI FONTAN

STAGE 3: AT 1-5 YEARS REDUCE ADMIXTURE & DIRECT FUNCTIONAL

VENTRICLE TO SYSTEMIC CIRCUIT FONTANS

Fontan Modifications

d'Udekem, Y. et al. Circulation 2007;116:I-157-I-164

Fontan surgical techniques: Classical atriopulmonary connection (A), Lateral tunnel (B), and extracardiac conduit (C)

Fontan Physiology

The sub-pulmonary ventricle is bypassed

Systemic venous return is diverted directly into the pulmonary arteries Goal is to provide adequate pulmonary blood flow

and cardiac output with minimal elevation in venous pressure

Systemic and pulmonary venous returns are separated: CYANOSIS is relieved VOLUME LOADING on the ventricle is

significantly reduced

AGE – 4 to 15 yearsNormal SINUS rhythmNormal SYSTEMIC VENOUS RETURNNormal RIGHT ATIRAL VOLUMEMean PULM. ARTERY PRESSURE <15 mmHgPULM. VASC. RESISTANCE < 4 Woods unitsPULM ART. TO AORTA DIAMETER RATIO > 0.75LVEF = 60%COMPETENT MITRAL VALVEABSENCE OF PULMONARY VALVE DISTORTION

Patient SelectionTEN COMMANDMENTS

Fontan Physiology

Fontan Outcomes

Despite the abnormal circuit, most patients with a Fontan circulation can lead a nearly normal life, including mild to moderate sport activities

More than 90% of hospital survivors are NYHA functional class I or II

Patient’s remain slightly desaturated with values in the low 90s

Fontan FAILURE

Fontan failure is defined as:

NYHA functional class III or IV

Death

Fontan Take-down / Conversion

Cardiac Transplantation

Fontans FAILURE

MRI is best for postoperative evaluation of patients with Fontan circulation

Cardiac Transplantation remains the only definitive treatment for those with failing Fontan circulation.

Fontan Circulation Complications

Complications after Fontan repair related to: Elevated pulmonary artery pressure, Increased venous pressure / Increased venous

congestion Anatomic abnormalities of the right and left

pulmonary arteries Atrial-ventricular valve regurgitation (AVVR) Poor LV function Stenosis / Dilatation of the Conduit

Fontans Complications

Fontans Complications - Pathophysiology

Fontans Complications - Pathophysiology

Fontans ComplicationsLEFT VENTRICLE

Volume overload dilatation, hypertrophy become hypocontractile.

Total bypass of the right side of the heart marked reduction of preload to the systemic ventricle systolic and diastolic dysfunction of the ventricle impaired compliance low cardiac output.

The congenital malformation itself also may be a predisposing factor for ventricular dysfunction

Systemic ventricle may be a morphologic right ventricle / indeterminate ventricle may fail after years of systemic loading

Fontans ComplicationsLEFT VENTRICLE

Fontans Complications LEFT VENTRICLE

Reduced preload is the dominant factor contributing to poor ventricular function

Failure manifests as exercise intolerance

Inotropes, afterload reducers, vasodilators and B-blockers are generally ineffective

Pulmonary vascular resistance will control cardiac output Improving pulmonary blood flow will improve

cardiac output

Fontan Complications PULMONARY CIRCULATION

Absence of the hydraulic force of the right ventricle paradox of Systemic Venous Hypertension (mean pressure, >10 mm Hg) and Pulmonary Artery Hypotension (mean pressure, <15 mm Hg).

Increase pulmonary vascular resistance. Pulmonary vascular resistance is an important

determinant of cardiac output in patients with Fontan circulation

Stenosis or leakage of surgical anastomoses may adversely affect pulmonary blood flow.

Fontans ComplicationsINFERIOR VENA CAVA

Chronic congestive heart failure ( CVP)

Increased Hepatic sinusoidal pressure

CirrhosisPortal Venous Hypertension

Hepatic Dysfunction.

Fontans ComplicationsRIGHT ATRIUM

ATRIOPULMONARY FONTAN CIRCULATION RA is exposed to elevated systemic and right

atrial pressure dilatation and hypertrophyDilatation Arrhythmia Stasis & Poor Blood Flow To The Lungs. Clot Formation.

Fontan Surgery may injure the sinus node or conducting fibers ATRIAL ARRHYTHMIA.

Fontans ComplicationsRIGHT ATRIUM

Predisposition to ATRIAL DYSRHYTHMIASIncidence - Up to 40% - 50% of patients 10 years

post-op Most commonly :

Intra-atrial Re-entry Tachycardia / Paroxysmal atrial tachycardia

Atypical Atrial Flutter Sinus node dysfunction Ventricular arrythmias (rare)

Safest treatment is immediate DC cardioversionLong term treatments include Medication,

Ablation, Pacemaker, Fontan Conversion

FONTAN CONVERSION

FONTAN CONVERSION

Extra cardiac Conduit – IVC to PA

Bidirectional Glenns Shunt – SVC to PA

Resection of the diated Right Atrium

Maze Procedure (Anti-arrythmic)

Epicardial Pacemaker

AFTER FONTAN CONVERSION

Fontans ComplicationsCOLLATERALS & SHUNTS

RIGHT-TO-LEFT SHUNTSIncomplete Closure Or A Residual Atrial Septal DefectFenestration between surgical conduits & right atrium

right-to-left shunt Surgical Redirection Of Coronary Sinus Blood flow to

the left atriumPulmonary Arteriovenous Malformations (20%) :

Due to the absence of pulsatile blood flow Underfilling of the pulmonary vascular bed Reduced hepatic venous factor

Aortopulmonary Collateral vessels are common arise from the thoracic aorta, internal mammary arteries, or

brachiocephalic arteries

Fontans ComplicationsLYMPHATIC SYSTEM

High venous pressure & impaired thoracic duct drainage Lymphatic system dysfunction.

Increased pulmonary lymphatic pressure interstitial pulmonary edema or lymphedema.

Leakage into the thorax or pericardium PERICARDIAL AND PLEURAL EFFUSIONS (often right-sided) and CHYLOTHORAX

Rx – Reduce CVP , Fenestration , Fontan Conversion / Take down

Fontans ComplicationsLYMPHATIC SYSTEM

PROTEIN-LOSING ENTEROPATHY (4%) Its cause is unclear

Elevated systemic venous pressure Elevated hepatic and portal venous pressure Loss of enteric protein

Interstinal Lymphangiectasis Loss of enteric proteinHypoproteinemia, Immunodeficiency,

Hypocalcemia, And CoagulopathyFatigue, Peripheral Edema, Pleural & Pericardial

Effusions, Ascites & Chronic Diarrhea. Low serum albumin level & Increased fecal α1-

antitrypsin levels

Fontans ComplicationsLYMPHATIC SYSTEM

PROTEIN-LOSING ENTEROPATHY (4%)

Poor prognosis 5-year survival 50%Associated with increased Mortality

Rx: Many treatments tried Dietary Modifications with high-protein and high medium-

chain triglycerides, Afterload Reducing Agents, Inotropic Agents, Digoxin,

diuretics Heparin, Albumin Infusions, Octreotide, Prednisone Fenestration / Fontan Conversion / Cardiac Transplantation

Fontans ComplicationsLYMPHATIC SYSTEM

PLASTIC BRONCHITIS (< 1%–2%)

Noninflammatory Mucinous Casts that form in the tracheobronchial tree and obstruct the airway.

Cause : unknown; High Intrathoracic Lymphatic Pressure Or

Obstruction of lymphatic flow Lymphoalveolar Fistula And Bronchial Casts

Fontans ComplicationsLYMPHATIC SYSTEM

PLASTIC BRONCHITIS (< 1%–2%)

Clinical manifestations : dyspnea, cough, wheezing, and expectoration of casts, severe respiratory distress with asphyxia, cardiac arrest, or death

Rx Repeat bronchoscopy to remove the thick casts ; Aerosolized urokinase or tissue plasminogen activator

Surgical ligation of the thoracic duct may cure by decreasing intrathoracic lymphatic pressure and flow

Fontan Circulation ComplicationsBLOOD VESSELS

Predisposition to COAGULOPATHIESThrombosis is more likely in patients with low CO and

venous stasisIncreased incidence of coagulation factor abnormalities

because of Hepatic Congestion Protein C Protein S ATIII deficiency

Chronic cyanosis–induced Polycythemia

Leads to chronic / recurrent Pulmonary Embolism

Anticoagulation / Asprin Prophylaxis of all patients is controversial

FONTANS MORTALITY

Predictors of ALL CAUSE MORTLITY / CARDIAC TRANSPLANT

Hypoplastic left heart syndrome

Protein losing enteropathy

Raised CVP

Diuretic treatment

FONTANS MORTALITY

Modes of death were as follows:

Sudden Cardiac Death Thromboembolism Heart FailureSepsisOthers

SUMMARY

The Fontan procedure is considered palliative and enables survival for several decades

“Perfect” Fontan Operation Was An Elusive Goal

Complications after Fontan are related to increased venous pressure, increased venous congestion, and chronic low cardiac output

SUMMARY

Fontans failure is difficult to reverse … so it should be prevented

Common long-term sequelae include severe right atrial dilation, atrial arrythmias, thromboemboli, hepatic dysfunction, progressive ventricular dysfunction and AV valve regurgitation, and worsening cyanosis from systemic venous collateralization, pulmonary arteriovenous malformations.

SUMMARY

Post-Fontan goals include maintaining adequate preload and minimizing increases in pulmonary vascular resistance

MRI is the best investigation

Cardiac Transplant is only definitive treatment

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