Surgical Treatment for Single Ventricle Masakazu Nakao Consultant, Paediatric Cardiothoracic Surgery

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History

2015

Blalock-Taussig shunt (Blalock & Taussig)

1944 1949 1951 1958 1961 1968

Experimental models by a few groups

Pulmonary artery banding (Muller & Dammann)

Glenn shunt (Glenn)

Bidiretional Glenn shunt (Dogliotti)

Fontan operation (Fontan)

Today

1971

Kreutzer operation (Kreutzer)

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Modifications

Adopted from B.J. Deal. “Challenges & opportunities living with a “Fontan” heart

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Indications

In single ventricle • Inadequate pulmonary flow

• Excessive pulmonary flow

• Intracardiac obstruction leading to either physiological

subpulmonary obstruction or subaortic obstruction

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Tricuspid Atresia

A. Normally related great arteries (70%) • Always cyanotic • Restrictive VSD / Infundibular stenosis in 50%

Progressive cyanosis

B. Transposed great arteries (30%) • Pulmonary flow is abundant in 70% • LV overload • Restrictive VSD / Infundibular stenosis

Decreased cardiac output

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Surgical Treatment - Overview • Fontan circulation

Fontan

Predominant ventricle

Body Lung

Normal

Left ventricle

Body

Right ventricle

Lung

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Surgical Treatment – Staged Strategy

1. First stage a. Inadequate pulmonary flow: Systemic-to-pulmonary shunt

b. Excessive pulmonary flow: PA banding

Prevention of pulmonary vascular disease is particularly important 2. Second stage

Bidirectional cavopulmonary shunt at 6-9 months 3. Third stage

Completion of Fontan circulation at 2-6 years of age

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Surgical Treatment – Flowchart

Single ventricle

Modified from Nakao M, Tsang VT. Tricuspid atresia: Key questions in congenital cardiac surgery. Eds. Moorjani N, et al. Tfm Pub Ltd, 2017

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Cavopulmonary Shunt vs Systemic-to-pulmonary Shunt

Systemic-to-pulmonary shunt Cavopulmlonary shunt

Efficiency Lower (Mixed blood from systemic flow to lung)

Greater (Systemic venous blood to lung)

Volume loading to ventricle More Less

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Ten Commandments

1. Age above 4 years 2. No distortion of lung arteries from prior shunt surgery 3. No AV valve leak 4. Normal venous drainage 5. Normal ventricular function (EF≥60%) 6. Normal heart rhythm 7. Normal RA size 8. Low PA pressure (≤15 mmHg) 9. Low pulmonary vascular resistance (< 4 units/m2) 10. Adequate PA size (PA: Aorta≥0.75)

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Current Management

1. Age above 4 years - Lower now 2. No distortion of lung arteries from prior shunt surgery - amendable 3. No AV valve leak - amendable 4. Normal venous drainage - amendable 5. Normal ventricular function (EF≥60%) - relatively important 6. Normal heart rhythm - not critical 7. Normal RA size - not critical 8. Low PA pressure (≤15 mmHg) - not as significant as 9, ≤17 mmHg 9. Low pulmonary vascular resistance (< 4 units/m2) - Critical 10. Adequate PA size (PA: Aorta≥0.75) - relatively important

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PA Index Pre-branching RPA diameter + LPA diameter Descending aorta diameter at the diaphragm McGoon ratio

Pre-branching RPA area + LPA area Body surface area Nakata index

The risks of failure of the Fontan circulation is higher for less than 1.8 (normal range: 2.0-2.5)

Lower Nakata index (< 250) has been identified as a risk factor (normal range: 330±30mm2/BSA)

The usefulness of these indices is controversial the compliance of the pulmonary vascular bed distortion of the pulmonary arteries

They don’t consider

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Surgical Management – Total Cavopulmonary Connection

• Lateral tunnel Fontan

• Extracardiac conduit Fontan

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Surgical Management – Extracardiac Conduit

Adopted from Operative Techniques in Cardiac and Thoracic Surgery 1997 2, 180-195

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1. MPA – closer to RPA than it appears 2. Adhesion behind aorta – obtain enough space 3. RPA – watch out early take-off 4. RSPV – prevent compression from the graft 5. Distal RA – don’t take CS accidentally 6. IVC anastomosis – Keep sewing margin, stretch properly,

check hepatic vein drainage

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7. Fenestration – 4mm punch, don’t take edge of the hole on the graft

Maintain sufficient path for R-L shunt Aim for postoperative saturation > 85%

van Doorn C, de Leval MR. Single ventricle: Surgery for congenital heart defect, third edition. Eds. Stark JF, de Leval MR, Tsang VT, John Wiley & Sons, 2006:543-558

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Surgical Management – Extracardiac Conduit: Size of Graft

Weight (kg) Diameter of graft (mm)

10-20 18

20-40 20

40< 24

• IVC can stretch to accommodate bigger size graft than the IVC diameter

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Adopted from Operative Techniques in Cardiac and Thoracic Surgery 1997 2, 180-195

Surgical Management – Lateral tunnel

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Adopted from Operative Techniques in Cardiac and Thoracic Surgery 1997 2, 180-195

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Adopted from Operative Techniques in Cardiac and Thoracic Surgery 1997 2, 180-195

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Surgical Management – Extracardiac conduit vs Lateral tunnel

Extracardiac conduit Lateral tunnel

Survival (10 years) 97% 84%

Survival (30 years) 62% 39%

Arrhythmias Less More

Anastomotic leak No leak Long-term complication

CPB time / AXC time Shorter ~ same / shorter Same ~ longer / longer

Haemodynamics Offseting – better??? T-shape

Survival quoted from Pundi KN, et al. 40-Year follow-Up after the Fontan operation: Long-term outcomes of 1,052 patients. JACC 2015;66(15):1700-1710

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Surgical Management – Offseting

Adopted from de Leval MR, et al. Use of computational fluid dynamics in the design of surgical procedures: Application to the study of competitive flows in : cavopulmonary connections. J Thorac Cardiovasc Surg 1996;111(3):502-513

Physiological ratio

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Short-Term Mortality

• Mortality in current era is approximately 1-10%

• The improvement is contributed by - more energy-efficient design - shorter bypass time - shorter cross-clamp time - staged operation - use of fenestration

• Complex cases such as heterotaxy and HLHS adversely affect

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Long-Term Mortality

• The survival rate in current era is: 85-97% at 5 years 83-95% at 10 years • Heart transplant for failing Fontan circulation carries unwarranted

outcome

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Outcome – Type of Fontan Surgery

Adopted from Pundi KN, et al. 40-Year follow-Up after the Fontan operation: Long-term outcomes of 1,052 patients. JACC 2015;66(15):1700-1710

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Outcome – Type of Pathology

Adopted from Pundi KN, et al. 40-Year follow-Up after the Fontan operation: Long-term outcomes of 1,052 patients. JACC 2015;66(15):1700-1710

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Short-Term Morbidities

• Low cardiac output

• Persistent pleural effusion

• Chylous leak

• Liver dysfunction

• Thrombus formation in the Fontan pathway

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Long-Term Morbidities

• Hepatomegaly and ascites

• Supraventricular arrhythmia

• Obstruction of Fontan pathway

• Leakage in intra-atrial baffle (lateral tunnel)

• Development of pulmonary arteriovenous fistula

• Protein-losing enteropathy

• Failing predominant ventricle requiring heart transplant

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Conclusion

• Fontan operation represents the best form of surgical treatment at the present time.

• Though knowledge and strategies for management for Fontan operation has improved, many questions remain unanswered.

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Further Reading

1. Deal BJ, et al. Management of the failing Fontan Circulation. Heart 2012;98:1098-1104

2. de Leval MR, et al. Four decades of Fontan palliation. Nature Reviews Cardiology 2010;7:520-527

3. Goldberg DJ, et al. The failing Fontan: etiology, diagnosis and management. Expert Rev Cardiovasc Ther. 2011;9(6):785-793.

4. Khairy P, et al. Long-term survival, modes of death, and predictors of mortality in patients with Fontan surgery. Circulation 2008;117;85-92

5. Pundi KN, et al. 40-Year follow-Up after the Fontan operation: Long-term outcomes of 1,052 patients. JACC 2015;66(15):1700-1710

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