*2.2.3 Total cavopulmonary connection*

To better understand the valve-less atriopulmonary anastomosis type of Fontan, de Leval et al. [19] performed hydrodynamic studies and found that (1) the right atrium is not an efficient pump in non-valved atriopulmonary connections, (2) pulsations in a non-valved circulation truly generate turbulence with consequent decrease in net flow, and (3) energy losses occur in the non-pulsatile chambers, corners, and obstructions. In an attempt to address these deficiencies, they developed a procedure which they named "total cavopulmonary connection." In this procedure, they connected the divided SVC, end to side, to the undivided right pulmonary artery (bidirectional Glenn), and the IVC blood is diverted through a composite intra-atrial tunnel (with the use of posterior wall of the right atrium as posterior wall of the tunnel) into the cardiac end of the divided superior vena cava, which in turn was connected to the PA. They felt that technical simplicity, maintenance of low right atrial and coronary sinus pressure, and reduction of risk of atrial thrombus formation are advantages of this type of operation. They performed this procedure on 20 patients and observed two early deaths and one late death. Postoperative hemodynamic studies were performed in 10 of the survivors which indicated good results. They recommended this type of operation for patients with a non-hypertrophied right atrium. While the total cavopulmonary connection was initially devised for patients with complex atrial anatomy and/or systemic venous anomalies, it has since been used extensively for all types of cardiac anatomy with one functioning ventricle and irrespective of venous anomalies.

Subsequent experimental studies by Sharma and his associates [20] indicated that complete or minimal offset between the orifices of the SVC and IVC into the right pulmonary artery decreases energy losses.

## *2.2.4 Extra-cardiac conduit*

Marcelletti et al. [21, 22] used an interposition extra-cardiac conduit from the IVC to the PA in place of lateral tunnel used in total cavopulmonary connection in 1990. Subsequently, most surgeons adopted this modification of total cavopulmonary connection, and currently extra-cardiac conduits are used in most Fontan operations.

### *2.2.5 Staged Fontan*

Since the vast majority of patients requiring Fontan operation present as neonates or in the early infancy, palliative procedures are performed at the time of presentation, and subsequently (at 12–18 months of age) the Fontan operation is undertaken. A considerable mortality (~16%) was seen with primary Fontan surgery, largely related to the impact of rapid changes in ventricular geometry and development of ventricular diastolic dysfunction. The concept of further staging the procedure by performing bidirectional Glenn procedure around 6 months of age followed by final Fontan between 12 and 18 months of age was introduced in early 1990s [23, 24]. Performing the Fontan procedure in stages appears to decrease overall mortality, most likely related to improving the ventricular function by correction of the afterload mismatch that is associated with one-stage Fontan procedure. At the current time, most centers prefer staged Fontan with bidirectional Glenn initially, followed later by extra-cardiac conduit diversion of the inferior vena caval blood into the PA.

### *2.2.6 Fenestrated Fontan operation*

In 1978, Choussat et al. proposed several criteria for performing Fontan operation [25]. Many cardiologists and surgeons have modified these criteria. Patients not meeting these criteria were deemed to be at a higher risk for a poor prognosis following a Fontan operation than patients who are within the limits of the set criteria. For the high-risk group, several investigators have proposed the concept of leaving a small atrial septal defect (ASD) open to facilitate decompression of the right atrium [26–28]. Laks et al. advocated closure of the atrial defect by constricting the preplaced suture in the postoperative period [28], while Bridges et al. [27] used a transcatheter closure method at a later date.

Higher cardiac output and significant decreases in the postoperative pleural effusions and systemic venous congestion were noted after a fenestrated Fontan procedure. In addition, the duration of hospitalization appears to have decreased. Nonetheless, these beneficial effects are at the expense of mild arterial hypoxemia and potential for paradoxical embolism.

While the fenestrated Fontan procedure was initially designed for patients at high risk for Fontan surgery, it has since been used in patients with modest or even low risk. Although rare, reports of cerebrovascular or other systemic arterial embolic events occurring after a fenestrated Fontan operation tend to contraindicate the use of fenestrations in patients with low or usual risk. In following years, fenestrated Fontan have been routinely used at most institutions. Some data indicate that routine fenestration is not necessary [29].

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palliation cohort.

*Fontan Operation: A Comprehensive Review DOI: http://dx.doi.org/10.5772/intechopen.92591*

*2.2.7 Device closure of Fontan fenestration*

used devices to accomplish such closures.

**3. Indications for Fontan operation**

candidate for Fontan.

functioning ventricle were selected for Fontan surgery.

Patients who have undergone a fenestrated Fontan operation or patients who have a residual atrial defect, despite correction, may have clinically significant right-to-left shunt causing varying degrees of hypoxemia. These residual defects should be closed not only to address arterial desaturation but also for prevention of paradoxical embolism [30, 31]. Although two types of fenestration closure, namely, constriction of the preplaced suture in the postoperative period [26, 28] and device closure later [27] were described, device closure is opted at most institutions. Closure of such defects can be performed by using transcatheter techniques [32–35]. The procedure is usually performed 6–12 months following fenestrated Fontan procedure. Although a number of devices have been used in the past [32–35], at the present time, Amplatzer septal occluders are the most commonly

The indications for opting for a Fontan operation are patients who have one functioning ventricle. At first, patients with tricuspid atresia were selected for this procedure [1, 2]. Shortly thereafter, patients with double-inlet left (single) ventricle were added to the indications for Fontan [36]. Following description of surgical palliation of hypoplastic left heart syndrome (HLHS) by Norwood et al. [37, 38] in the early 1980s, HLHS became the major lesion requiring Fontan operation. Subsequently, mitral atresia (with normal aortic root), unbalanced atrioventricular septal defects (AVSDs), pulmonary atresia with intact ventricular septum with markedly hypoplastic right ventricle, and other complex heart defects with one

Attempts to insert prosthetic ventricular septum for single ventricle patients met with problems, leading to abandoning such procedures. Thereafter, Fontan became a preferred treatment method. With reasonably good results of Fontan, the pendulum swung so that any patient who could not undergo complete repair became a

A middle of the road method, the so-called one-and-one-half ventricle repair was developed for patients with pulmonary atresia with intact ventricular septum with modest-sized right ventricle. In this procedure, a bidirectional Glenn procedure to divert the SVC flow into the PA is performed and allows the small right ventricle to pump the IVC blood into the pulmonary circuit, and the patent foramen ovale is closed. It is generally considered to be a better option than Fontan, although, to my knowledge, there are no comparative studies to assess this issue.

Because of relatively high mortality rates (17.0–31.7%) [39, 40] and low actuarial survival rates (66.5% at 5 years and 64.4% at 15 years) [41] for unbalanced AVSD patients following Fontan, a number of institutions attempted single stage or staged biventricular repair or conversion from single ventricle (Fontan) to biventricular repair [39, 42–47]. Detailed analysis by Nathan et al. [39] suggested that the biventricular repair and conversion from single ventricle (Fontan) to biventricular repair groups had reasonably similar mortality rates and a similar need for cardiac transplantation, but these parameters were lower than those seen in the Fontan

Cardiac transplantation is a surgical alternative in the management of HLHS [48] and other single ventricle lesions. While heart transplantation was used at several institutions initially for HLHS, because of non-availability of

*Advances in Complex Valvular Disease*

*2.2.4 Extra-cardiac conduit*

operations.

*2.2.5 Staged Fontan*

blood into the PA.

*2.2.6 Fenestrated Fontan operation*

used a transcatheter closure method at a later date.

indicate that routine fenestration is not necessary [29].

and potential for paradoxical embolism.

right pulmonary artery decreases energy losses.

Subsequent experimental studies by Sharma and his associates [20] indicated that complete or minimal offset between the orifices of the SVC and IVC into the

Marcelletti et al. [21, 22] used an interposition extra-cardiac conduit from the IVC to the PA in place of lateral tunnel used in total cavopulmonary connection in 1990. Subsequently, most surgeons adopted this modification of total cavopulmonary connection, and currently extra-cardiac conduits are used in most Fontan

Since the vast majority of patients requiring Fontan operation present as neonates or in the early infancy, palliative procedures are performed at the time of presentation, and subsequently (at 12–18 months of age) the Fontan operation is undertaken. A considerable mortality (~16%) was seen with primary Fontan surgery, largely related to the impact of rapid changes in ventricular geometry and development of ventricular diastolic dysfunction. The concept of further staging the procedure by performing bidirectional Glenn procedure around 6 months of age followed by final Fontan between 12 and 18 months of age was introduced in early 1990s [23, 24]. Performing the Fontan procedure in stages appears to decrease overall mortality, most likely related to improving the ventricular function by correction of the afterload mismatch that is associated with one-stage Fontan procedure. At the current time, most centers prefer staged Fontan with bidirectional Glenn initially, followed later by extra-cardiac conduit diversion of the inferior vena caval

In 1978, Choussat et al. proposed several criteria for performing Fontan operation [25]. Many cardiologists and surgeons have modified these criteria. Patients not meeting these criteria were deemed to be at a higher risk for a poor prognosis following a Fontan operation than patients who are within the limits of the set criteria. For the high-risk group, several investigators have proposed the concept of leaving a small atrial septal defect (ASD) open to facilitate decompression of the right atrium [26–28]. Laks et al. advocated closure of the atrial defect by constricting the preplaced suture in the postoperative period [28], while Bridges et al. [27]

Higher cardiac output and significant decreases in the postoperative pleural effusions and systemic venous congestion were noted after a fenestrated Fontan procedure. In addition, the duration of hospitalization appears to have decreased. Nonetheless, these beneficial effects are at the expense of mild arterial hypoxemia

While the fenestrated Fontan procedure was initially designed for patients at high risk for Fontan surgery, it has since been used in patients with modest or even low risk. Although rare, reports of cerebrovascular or other systemic arterial embolic events occurring after a fenestrated Fontan operation tend to contraindicate the use of fenestrations in patients with low or usual risk. In following years, fenestrated Fontan have been routinely used at most institutions. Some data

**130**
