Surgical Evolution Towards Fontan

Dr. Kamal K. Pourmoghadam, Ppediatric Cardiac Surgeon

Surgical Evolution

Early Palliative Efforts
–Blalock-Taussig Shunt (1945)
–Pulmonary artery banding (1952)
Alternative to expectant Therapy
Not part of staged approach
Septation of the Heart
–First attempt at definitive repair for functional single ventricle
•Kirklin & Barratt-Boyes (1956)
•Sakakibara & colleagues (1972)
•Edie & Malm (1973)
•McGoon & Danielson (1977)
•Doty (1979)
–Very high mortality rate
–Frequent major complications
•Complete Heart Block (CHB)
•Residual ventricular septal defect (VSD)
•Atrioventricular (AV) valve incompetence
•Sudden Death
nSuperior Vena Cava to Pulmonary Artery Shunt (cavopulmonary shunt)
–Right ventricular exclusion
•Rodbard & Wagner (1949)
•Warden , De Wall and Varco (1955)
–Carlon & colleagues (1950)
•End-end anastomosis of proximal azygous to RPA, ligation proximal SVC
–  Glenn and Patino (1954)
•“Unidirectional” Glenn shunt
Dogliotti (1961), Haller (1966) and Azzolina (1972)
–“Bidirectional” Glenn shunt
Advantages of cavopulmonary shunt
–Increased pulmonary blood flow without increased volume load
–Transpulmonary blood flow without subpulmonary ventricle

Fontan’s and Kreutzer’s Procedure.

Definitive treatment of tricuspid atresia
–Fontan (1968)
•First definitive successful physiologic repair
Patient selection criteria (Choussat and Fontan)
–Age ³ 4 years
–Sinus rhythm
–Normal systemic venous connection
–Normal right atrial volume
–Mean pulmonary artery pressure < 15mm Hg
–Pulmonary vascular resistance < 4 units/m2
–Ratio pulmonary artery/aortic diameter > 0.75, with normal size pulmonary branches
–Good ventricular function (ejection fraction ³ 0.60)
–No mitral valve incompetence
–No pulmonary distortion by previous shunt
Kreutzer and colleagues performed their first definitive repair of tricuspid atresia in 1971
–Similar physiologic endpoint as the Fontan
–Different technique
•Anastomosis of RA appendage/distal MPA
•No homograft valve at RA/IVC junction
•No Glenn Shunt
•Fenestrated
Modifications to incorporate the hypoplastic right ventricle
–Bowman and colleagues (1978)
–Bjork and colleagues (1979)
Results inconsistent
Evolution of the modifications of Fontan’s and Kreutzer’s procedures
–Application to other forms of functional single ventricle
–Homograft valve implantation no longer necessary
–Maintaining integrity of the pulmonary artery confluence

Modifications of Fontan’s and Kreutzer’s Procedure
deLeval and colleagues (1988)
–Introduction of total cavopulmonary connection (TCPC)
•SVC to RPA end-side anastomosis
•Construction of intra-atrial tunnel
•IVC flow to proximal divided SVC
•Proximal SVC to MPA anastomosis
deLeval and colleagues
–Interposition tube graft between the IVC and SVC orifices
Norwood and Danielson (personal communication)
–Utilization of an  intra-atrial tube graft
Marcelletti and Colleagues
–Extracardiac total cavopulmonary connection
–Advantages
•Avoidance of any intra-atrial suture lines
•Shielding the right atrium from high central venous pressures
Marcelletti and Colleagues
–Technical modification for extracardiac total cavopulmonary connection
•The superior vena cava is divided and anastomosed to the ipsilateral branch pulmonary artery in an end-side fashion
•The inferior vena cava is transected at its junction with the right atrium
•The right atrial end is oversewn
•The flow of blood is directed from the inferior vena caval orifice to the underside of the ipsilateral branch pulmonary artery via a conduit

Staging Fontan’s Operation
Despite improvements significant morbidity and early mortality remained
–Elevated central venous pressures
–Persistent pleural & peritoneal effusions
–Tachycardia
–Hypotension
–Hemodynamic instability
Prediction of favorable outcome post Fontan operation was difficult
Donofrio, Jacobs, and Norwood (1995)
–Palliated state created a chronic volume load on the heart
–Fontan completion led to significant increase in the mass-volume ratio of the single ventricle
–Deleterious effects on early post operative    hemodynamics
Predictors of unfavorable outcome post Fontan
–Older age
–Hypertrophied systemic ventricle
Pennigton and colleagues
–Fontan post BDG yielded lower operative mortality
Philosophy of staging Fontan’s operation

Norwood and colleagues
–The hemi-Fontan operation , 1989
–Advantages of hemi-Fontan
•Physiologic equivalent to BDG
•Augments central pulmonary arteries
•Enlarges superior cavopulmonary amalgamation
•Enlarges RA to SVC connection
•Maintains anatomic continuity of RA and SVC
•Results in improved flow dynamics after TCPC
Advantages of bidirectional Glenn anastomosis
–Technically simple
–Can accomplish without aortic cross clamp
–Can accomplish without cardiopulmonary bypass
–Natural precursor to extracardiac Fontan
Prior to staging Fontan
–Single ventricle pumps pulmonary & systemic cardiac output
–Chronic volume load
Hemi-Fontan or BDG reduce volume load
–Alter ventricular compliance
–Ventricular filing maintained
–Avoiding low cardiac output states
Concept of patient preparation
–Remove other sources of pulmonary blood flow
–Optimize branch pulmonary artery architecture
–Relieve systemic ventricle outflow obstruction
–Repair AV valve regurgitation
–Replacing earlier theoretical patient selection criteria
Fenestration of cavopulmonary pathway
–Achieve benefits seen by staging Fontan
–Decompresses systemic venous pathway
–Improved cardiac output
–Decreased systemic arterial saturation
–Originally performed by Kreutzer, 1971
Bridges and colleagues
–Adjustable snared ASD, 1988
Jacobs and colleagues
–Multiple small fenestrations

Surgical Methods
Preparatory staging operations
–Hemi-Fontan operation
–Bidirectional Glenn anastomosis
Completion Fontan operation
–Mass-volume ratio optimized
–Ventricular remodeling optimized
–12-24 months after first stage
–Generally 2 years for Intraatrial lateral tunnel
–Generally 3 years for extracardiac pathway
The Completion Fontan operation (lateral tunnel )
–Arterial BP, ABG monitored, avoid CVP lines
–Ascending aorta, RA cannulated for CPB
–Caval cannulas, snares avoided
–CPB 120-150 ml/KG/min, cooling to 18°C
The Completion Fontan operation (lateral tunnel )
–Aorta cross clamped, cardioplegia infused
–Oblique RA incision, avoid sulcus terminalis
–Homograft dam RA-SVC junction resected
–PTFE gusset used to fashion the lateral tunnel
The Completion Fontan operation (Cont. )
–Lateral tunnel is fenestrated
–Lateral tunnel completed as PTFE incorporated into atriotomy closure
–DHCA, 20 minutes
–Ventilation resumed during re-warming
–Pulmonary venous pressures monitored by transthoracic atrial lines
–Low dose inotropic support
–Single anterior chest tube
–Extubated 4-6 hours post operatively
–Meds, aspirin, ACE inhibitors, diuretics
–Average length of stay, 10 days
The Completion Fontan operation (extracardiac pathway)
–Hemodynamic monitoring
–IVC transected during DHCA
–PTFE conduit interposed between IVC & superior cavopulmonary amalgamation
–Patients with prior BDG shunts
•Conduit anastomosed end-side to RPA
–Patients with prior hemi-Fontan
•Superior end anastomosed to the superior cavopulmonary amalgamation through a cruciate incision
–Fenestration
•Side-side anastomosis between conduit & RA
•Interposition graft between conduit & RA

Results of Surgery
Mortality
–Improved early survival
•Technical modifications
•Improved postoperative care
•Survival, 75%-83% in the 1970’s
•Survival over 90% in the 1990’s
•Cetta and colleagues, 1996
–Decrease mortality from 16%-9%
•Gentles and colleagues, 1997
–Decreased early failure rate from 27.1% to 7.5%
•Survival over 93%, Mayer and colleagues, 2001
•Over 80 consecutive Fontans since 1997 with no deaths, author’s experience

Post Fontan Consideration
Functional status
–Exercise tolerance
–Early volume unloading improves         long-term results
–Neurological Status
Thromboembolic events
–Incidence varies 3%-20%, reported as late as 16 years
–MPA cul-de-sac, source systemic emboli
–Hypercoagulable state
–No widely accepted anticoagulation strategy
–Author’s preference, one baby aspirin daily
Systemic ventricular outflow obstruction
–Frequent in functional single ventricle
–Preemptive strategy
Arrhythmias
–Supraventricular arrhythmias, high incidence
•Driscoll & colleagues, 1992
•Fishberger & colleagues, 1997
–Hypotheses
•Trauma to SA node, blood supply
•Long atrial incision, suture lines
•Elevated RA pressures
•Anatomical factors
–AV discordance
–Heterotaxy
Arrhythmias (cont.)
–Hemodynamic risk factors
–AV valve regurgitation
–Abnormal AV valve
–Preoperative supraventricular tachyarrhythmias
–Older age at operation
•Lower risk associated with TCPC
–Management
•Medical
•Permanent pacing
•Fontan conversion to TCPC
–Mavroudis and colleagues
•Fontan conversion to TCPC
•Atrial reduction
•Cox-Maze III modification
•Permanent pacing
Protein losing enteropathy
–Enteric losses of serum proteins, electrolytes
•Edema
•Immunodeficiency
•Fat malabsorption
•Hypercoagulopathy
•Incidence, 3.7%-13.4%
•Mortality, 50% at 5yrs, 80% at 10yrs
•Etiology, unclear, low cardiac output, low flow state
–Management
•Cardiac catheterization, hemodynamic evaluation
•Fenestration
•Pacing, sinus node dysfunction
•Medical
•Cardiac transplant

References:
Website: https://kamalpourmoghadam.com
Blog: https://drpourmoghadam.home.blog/
News: https://hippocratesguild.com/dr-kamal-pourmoghadam
News: https://medicogazette.com/dr-kamal-pourmoghadam#425f92ce-0ccc-4fe2-8c31-56cf497704f4
News: https://hype.news/dr-kamal-pourmoghadam/
News report about Dr. Pourmoghadam: http://www.tiogapublishing.com/features/the_marketplace/covington-tot-returns-home-to-pennsylvania-after-lengthy-oklahoma-hospital/article_04865c00-0ae5-11e1-aec8-001cc4c002e0.html
Linkedin: https://www.linkedin.com/in/kamal-pourmoghadam-9a796157/

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