الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
The right ventricle hasn’t gained enough attention during the past decades, compared to
the left ventricle. Recently, the interest in the right ventricle, its impact and risk factors, has
started to gain momentum, special within the congenital heart diseases community. The right
ventricle in congenital heart disease is involved through one or more of the following
mechanisms:
• Volume loaded right ventricle
• Pressure loaded right ventricle
• Combined volume and pressure loaded right ventricle
• Hypoplastic right ventricle
• Systemic right ventricle
• Single right ventricle
• Right ventricular dysfunction due to myocardial disease or coronary abnormality
Therefore, we decided to study the impact of patient characteristics and management
algorithms on outcomes of two major congenital heart diseases involving the right ventricle;
Tetralogy of Fallot with Pulmonary Atresia (an example of pressure loaded right ventricle), and
Single Right Ventricle.
The first group, Tetralogy of Fallot with Pulmonary Atresia, represents patients with a
compromised subpulmonary ventricle, subjected mainly to pressure overload. The final goal of
repair is to close the ventricular septal defect and create a right ventricle to pulmonary artery
connection. The successful closure of the ventricular septal defect depends on the ability of the
pulmonary vascular bed to accept a full cardiac output at a right ventricular pressure of 60% to
70% of systemic (preferably less than two-thirds of systemic), along with good systemic
hemodynamics. We decided to study the optimal method to achieve a biventricular repair with
the fewest operations while basing flow to the lungs on the native intrapericardial pulmonary
arterial circulation whenever possible. Our aim was to assess the effect of pulmonary arterial
morphology and source of pulmonary blood flow, as well as different management strategies on
achieving complete biventricular repair.
Summary. Conclusion, and Recommendations
144
The second group, single right ventricle, represents those patients who undergone a
univentricular repair based on a right univentricular morphology, as in Hypoplastic left heart
syndrome, unbalanced atrio-ventricular canal, and double outlet right ventricle with mitral
atresia. Our objective was to evaluate the effect of right univentricular morphology, as well as
other perioperative risk factors, on mid-term outcomes following extracardiac Fontan procedure.
Tetralogy of Fallot with Pulmonary Atresia
Tetralogy of Fallot with pulmonary atresia is a heterogeneous group of defects,
characterized by diverse sources of flow of blood to the lungs, which often include multiple
systemicto-pulmonary collateral arteries. Controversy surrounds the optimal method to achieve a
biventricular repair with the fewest operations while basing flow to the lungs on the native
intrapericardial pulmonary arterial circulation whenever possible. We describe an individualized
approach to this group of patients that optimizes these variables.
Over a consecutive 10-year period, we treated 66 patients presenting with tetralogy of
Fallot and pulmonary atresia according to the source of the pulmonary arterial flow. Patients
were grouped according to whether the flow of blood to the lungs was derived exclusively from
the intrapericardial pulmonary arteries, as seen in 29 patients, exclusively from systemic-topulmonary
collateral arteries, as in 5 patients, or from both the intrapericardial pulmonary and
collateral arteries, as in the remaining 32 patients. We divided the latter group into 9 patients
deemed simple, and 23 considered complex, according to whether the pulmonary arterial index
was greater than or less than 90 mm2/m2, and whether the number of collateral arteries was less
than or greater than 2, respectively.
We achieved complete biventricular repair in 58 patients (88%), with an overall mortality
of 3%. Repair was accomplished in a single stage in all patients without systemic-to-pulmonary
collateral arteries, but was staged, with unifocalization, in the patients lacking intrapericardial
pulmonary arteries. Complete repair without unifocalization was achieved in all patients with the
simple variant of the mixed morphology, and in 56% of patients with the complex variant. The
average number of procedures per patient to achieve complete repair was 1, 2.2, 3.8, and 2.6 in
patients with exclusively native intrapericardial, simple and mixed, complex and mixed and
exclusively collateral pulmonary arterial flow, respectively.
Summary. Conclusion, and Recommendations
145
We conclude that an individualized approach based on the morphology of the pulmonary
arterial supply permits achievement of a high rate of complete intracardiac repairs, basing
pulmonary arterial flow on the intrapericardial pulmonary arteries in the great majority of cases,
and has a low rate of reoperation and mortality.
Single Right Ventricle (Right Ventricular Morphology in Patients
undergoing Fontan Procedure)
The impact of right ventricular morphology on patients undergoing Fontan procedure,
and whether it imposes a risk factor or not, continues to be a matter of controversy. Our aim was
to evaluate the effect of univentricular morphology, as well as other perioperative risk factors, on
mid-term outcomes following extracardiac Fontan procedure using a homograft conduit.
Over a ten-year period ending in 2007, 128 consecutive patients (mean age of
4.4±3.2years) underwent an extracardiac Fontan using an aortic homograft for the inferior cava–
to–pulmonary artery conduit. The single functional ventricle was of left ventricular morphology
in 70/128 patients (55%) and right in 58/128(45%). Right univentricular morphology was
associated with low age at operation (3.79 ± 0.35 years vs. 5 ±4.29 years, p=0.0225).
124/128 patients (97%) survived to hospital discharge. 120/124 patients (97%) were
discharged on aspirin, and 4/124 (3%) on warfarin. 38/128 patients (29%) had prolonged pleural
effusions (> 10 days) with risk factors being lack of a patent fenestration (38/102 vs. 0/26,
p=0.006, F=19.81) and a low pulmonary artery index (187 ± 25 vs. 218 ± 24 mm2/m2, p<0.001,
F=2.52), and a high end-diastolic pressure (6.7 ± 1.4 v 5 ± 1.3 mmHg, p < 0.001, F=0.21).
20/128 patients (16%) had postoperative arrhythmias with right (vs. left) univentricular
morphology being the most important risk factor (18/58 vs. 2/70, p<0.0001, F= 39.24), in
addition to a low pulmonary artery index (176 ± 15.82 mm2/m2 vs. 214.66 ± 26.47 mm2/m2,
p<0.0001, F=14.53), high end-diastolic pressure (11.40 ± 1.73 mmHg vs. 7.66 ± 2.79 mmHg,
p<0.0001, F= 13.12). Risk factors for death included atrioventricular valve regurgitation (2.5 ±
0.5 vs. 0.5 ± 0.6, p < 0.0001, F=46.65), high pulmonary vascular resistance (3.1 ± 0.25 vs. 2.4 ±
0.5 Woods, p=0.006, F=4.23), and cardiopulmonary bypass with oxygenator (3/84 vs. 1/44,
p<0.001, F=0.64). At 4.9 ± 2.1years follow-up, there have been no documented thromboembolic
events, circuit revisions, conduit replacements, or late deaths.
Summary. Conclusion, and Recommendations
146
The extracardiac Fontan is a safe and effective operation. Using a homograft eliminates
the need for long-term anticoagulation with warfarin in most patients. Right univentricular
morphology was associated with a greater risk for developing postoperative arrhythmias, which
may have an effect on long term survival.
Recommendations
• The right ventricle is of particular importance in congenital heart diseases. We were
able to study its impact and performance in only two patients’ groups, those with
tetralogy of Fallot with pulmonary atresia and those with single right ventricle. However,
studies should be directed to include other groups involving a:
Volume loaded right ventricle
Pressure loaded right ventricle (an example was covered in this study)
Combined volume and pressure loaded right ventricle
Hypoplastic right ventricle
Systemic right ventricle
Single right ventricle (an example was covered in this study)
Right ventricular dysfunction due to myocardial disease or coronary abnormality
• The right heart should not be studied in isolation of its left-sided counterpart. There is
virtually no aspect of cardiac anatomy, physiology, or disease that is not influenced by
biventricular interactions.
• More meetings and conferences should be held in an attempt to reach a consensus on the
morphology, methods of evaluation, and management strategies for congenital diseases
involving the right ventricle.
• As regarding tetralogy of Fallot with pulmonary atresia:
An individualized approach to the management of tetralogy of Fallot and
pulmonary atresia should be adopted, based on the morphology of the pulmonary
arterial supply, in an attempt to achieve a biventricular repair with the fewest
operations while basing flow to the lungs on the native intrapericardial pulmonary
arterial circulation whenever possible.
Summary. Conclusion, and Recommendations
147
Patients should be classified according to the morphology of their pulmonary
circulation and the need to undergo surgical unifocalization in order to achieve a
complete intracardiac repair.
Patients in whom pulmonary flow is derived exclusively from the native
intrapericardial pulmonary arteries are deemed able, safely and reliably, to
undergo a single-stage complete intracardiac repair.
Patients with the simple-mixed-variant (Pulmonary arteries ≥ 90 mm2/m2,
Systemic-pulmonary collateral arteries ≤ 2) can reliably and safely undergo a
complete repair without unifocalization.
Patients with the complex variant of mixed arterial supply (Pulmonary arteries <
90 mm2/m2, Systemic-pulmonary collateral arteries > 2) may not be able to
reliably undergo intracardiac repair based on the intrapericardial pulmonary
arteries alone. Unifocalization may be necessary in order to achieve a complete
repair if interventional procedures failed to recruit enough bronchopulmonary
segments.
Patients in whom pulmonary flow is derived exclusively from collateral arteries, a
single-stage unifocalization through a midline sternotomy is warranted in order to
create a new pulmonary arterial confluence, which can then be connected to the
right ventricle by means of a conduit. The intracardiac repair is better performed
at a separate operation.
A prospective randomized trial, with a longer follow-up is recommended to
validate the results of this study.
A universally accepted method to quantitate the capacitance and compliance of
the pulmonary vascular bed should be adopted to help compare different schemes
for management.
Summary. Conclusion, and Recommendations
148
• As regarding the single right ventricle (Right ventricular morphology in patients
undergoing Fontan procedure):
The extracardiac Fontan is a safe and effective operation, and should be adopted.
It may have advantages over intracardiac palliation by eliminating intra-atrial
suture lines, and frequently avoiding the use of pump oxygenators.
Using a homograft conduit, during the extracardiac Fontan, should be considered
as it eliminates the need for long-term anticoagulation with warfarin in most
patients.
Right univentricular morphology is associated with a greater risk for developing
postoperative arrhythmias, which may have an effect on long term survival.
Therefore care should be taken when operating on those cases.
Preoperative factors such as low pulmonary artery index, high pulmonary
vascular resistance, atrioventricular valve regurge, and high end-diastolic
ventricular pressure are risk factors for morbidity and mortality after extracardiac
Fontan. Such factors should be taken into consideration during patients’ selection.
A prospective randomized trial with a longer follow-up should be done to validate
the results of this study.
Serial 24 hours Holter studies should be done to all patients routinely, at followup,
to help detect asymptomatic as well as symptomatic arrhythmias.
Angiography, transesophageal echocardiography, and radionuclide studies are
superior to transthoracic echocardiography in detection of thromboembolism, and
should be used to follow-up patients after extracardiac Fontan.