Clinical Outcomes in Fenestrated Extra-Cardiac Fontan in Low Preoperative Risk Profiles

Study Population:

This study will include all patients referred for an elective Fontan procedure at the period of the study, who demonstrated a standard risk profile. An Informed consent will be obtained from the guardians before enrollment in the investigation. All procedures followed will be in accordance with institutional guidelines.

Randomization Technique:

Patients will be assigned to undergo either a fenestrated or non-fenestrated Extra-cardiac Fontan, based on a table of randomly generated numbers. Preoperative clinical data will be collected and compared to ensure appropriate randomization.

Preoperative Evaluation:

Enrolment Criteria:

Preoperative evaluation consists of ECG, transthoracic echocardiogram, and complete cardiac catheterization.

Patients with the following parameters will be eligible for enrollment in the study:

Sinus Rhythm Atriovnetricular valve regurgitation not more than mild Aortic (neoaortic) valve regurgitation not more than mild Normal systolic dominant ventricle function Mean pulmonary artery pressure not more than 15 mmHg (measured directly or estimated by pulmonary vein wedge pressure) Pulmonary vascular resistance not more than 2 woods unit End diastolic ventricular filling pressure not more than 8 mm Hg

Patient with the following will not be eligible for inclusion:

Patients with pulmonary artery distortion, stenosis or thrombus requiring surgical or interventional additional procedures before or during the Fontan operation. Pacemaker insertion before or during Fontan operation. Significant pulmonary arteriovenous malformations (AVMs) rendering fenestration potentially a cause of excessive cyanosis. Patients for whom the cardiology/cardiac surgery case conference decision is strongly in favor of fenestration for any other cause.

Ventricular filling pressure will be directly measured as the end-diastolic pressure in the dominant systemic ventricle. The degree of systemic atrioventricular valve regurgitation will be assessed semi-quantitatively by echocardiographic color Doppler, primarily based on width of jet origin. The regurgitation jet will be graded as none, mild, moderate, or severe. Rhythm is assessed with preoperative ECG or Holter monitor (if required). Coil occlusion of aortopulmonary collaterals is not an exclusion criterion and is recommended before the Fontan operation.

Operative Technique and postoperative management:

Treatment Patients underwent an extracardiac Fontan operation. The extracardiac Fontan channel will be constructed with a Polytetrafluoroethylene (PTFE) tube graft from the inferior vena cava to the pulmonary artery. The size if the graft is determined by the surgeon and ranged from 16 to 22 mm in diameter. The fenestration consists of a single 3- to 6-mm communication between the Fontan channel and the common atrium.

Postoperative treatment will include administration of captopril, and aggressive use of diuretics. All patients will receive aspirin (81 mg per day) and warfarin with a target International Normalized Ration INR of 2-2.5 beginning on the first postoperative day. To maximize caloric intake, patients ill not be fluid restricted after the initial postoperative period. All patients will be placed on fat free diet for 6 weeks. Chest tubes will be left in place until drainage is less than 5 mL/kg in a 24-hour period. A chest tube will be reinserted only if a symptomatic pleural effusion is diagnosed. Steroids and Octreotide will be started after 2 weeks of persistent drainage or immediately if Chylothorax is diagnosed biochemically.

The attending cardiologist and surgeon determined the need for and timing of postoperative cardiac catheterization. Patients will be discharged from the intensive care unit when hemodynamic and respiratory stability is ensured and a stable heart rhythm is maintained. The patients will be discharged from hospital after all chest tubes are removed and when the clinical status permits.

Assessment of Outcomes:

The primary end is the total length of chest tube drainage in days. If chest tube reinsertion is required during the same admission, this time will be added to the primary outcome. Other outcome variables include length of stay in the intensive care unit, total hospital stay in days, total amount of chest tube drainage, occurrence of stroke,readmissions, reoperation, or death within 90 days of discharge. All end points are defined a priori. The day of surgery counted as day 1 for all variables. All reoperations will be assessed including returning to the operating room for bleeding or poor hemodynamics, replacement of chest tubes, cardiac catheterization, and late fenestration.

Statistical Analysis:

Sample size estimates is based on a retrospective analysis of the last 100 patients who underwent the Fontan procedure at out institutionwith 80% power to avoid a type II statistical error. A reduction in total chest tube drainage days of 15% is considered clinically significant. The median length of chest tube drainage (estimated as one day less than the median postoperative length of hospitalization) was 19 days. Given a clinically significant difference of 15%, the calculated days of difference were 19 X 0.15 = 2.85. We set the relevant difference to be 3 days. Using a modified Lehr's equation for sample size in count data, we estimate the number in each group to be, n=4/〖(√(γ_1 )-√(γ_2 ))〗^2 =4/〖(√19-√16)〗^2 =31patients.

Descriptive statistics will be calculated for all variables. Medians and ranges describe continuous variables. Categorical variables will be summarized as frequencies. The Mann Whitney U test will be used for all continuous variables; analysis and Fisher's exact test will be applied for all dichotomous variables.

Count data for hospital length of stay, intensive care unit length of stay, and length of chest tube drainage will be compared by means of Poisson regression or Cox proportional hazards models. A probability value of 0.05 will indicate statistical significance. All calculations were performed with R-project statistical software (www.r-project.org).