Single Ventricle Treatment & Management

Updated: Aug 09, 2018
  • Author: Alvin J Chin, MD; Chief Editor: Howard S Weber, MD, FSCAI  more...
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Treatment

Medical Care

Admit patients with single ventricles for testing and surgical intervention. Evaluation as an inpatient in an intensive care setting is advised for patients with single ventricle.

Administration of intravenous prostaglandin E1 soon after birth is indicated in patients with severe pulmonary outflow tract or aortic arch obstruction.

The need for introduction of an arterial line and assisted ventilation can be judged best from the initial arterial blood gas measurement.

Consultations

Consult with a pediatric cardiologist and a cardiothoracic surgeon.

Transfer

Transfer may be required for further diagnostic evaluation and surgical intervention.

Diet and activity

No special diet is required.

No activity restrictions are needed if coexistent subaortic (and/or aortic) hypoplasia has been successfully relieved. [56]

The resting cardiac index of patients prior to the Fontan operation is about 70%-80% of normal. Also, a limited ability to increase cardiac output typically results in decreased exercise capacity.

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Surgical Care

Because the pulmonary vascular resistance gradually falls over the first few months of life, conversion to a cavopulmonary or atriopulmonary circulation cannot be safely accomplished in the first few days of life.

Presence of pulmonary outflow tract stenosis or aortic arch obstruction

If pulmonary stenosis is present, its severity dictates whether a systemic-to-pulmonary artery shunt is needed after ductal closure. If aortic arch obstruction is present instead, the most widely adopted approach is to reestablish unobstructed aortic arch flow and to limit pulmonary blood flow. As a way of limiting pulmonary blood flow, banding of the pulmonary artery has given way to other methods because most patients with arch obstruction have a narrow bulboventricular foramen.

Although it may not be initially restrictive, the bulboventricular foramen tends to reduce in diameter over time and may precipitously reduce in caliber following volume-unloading procedures, including pulmonary artery banding (as well as the hemi-Fontan and Fontan operations).

To avoid the possibility of hemodynamically important systemic outflow tract stenosis, a Norwood-type reconstruction (proximal pulmonary artery–to–aorta anastomosis) is currently favored. Enlarging the bulboventricular foramen by resection of muscle is hazardous because of the proximity of the conduction system and the frequent presence of atrioventricular valve attachments to the rim.

Physiologic sensitivity of infants palliated with Norwood-type procedure

The physiology of the infant palliated with a Norwood-type procedure has been widely observed to be relatively fragile, and this appears to be due to the diminutive native aorta, although this is not usually the case in single ventricle patients. Because coronary arterial flow is largely or, in the case of aortic valve atresia, totally dependent on retrograde aortic perfusion, the coexistent modified Blalock-Taussig shunt sets up a "diastolic steal" phenomenon, which is highly sensitive to changes in pulmonary vascular resistance. In fact, the mortality during the time between stage 1 and stage 2 has remained high for decades and is so high that some centers keep patients in the hospital for the entire interstage period. [57]

Creation of a cavopulmonary circulation

Creation of a cavopulmonary circulation is more safely accomplished in stages over 1-2 years because acute volume unloading is associated with an acute increase in ventricular wall thickness. This wall thickness increase markedly alters the diastolic performance of the single ventricle and can limit cardiac output. Because the cardiac output falls by a lesser amount, the hemi-Fontan procedure results in improved systemic blood flow (cardiac output) than the nonfenestrated "complete Fontan" procedure. [58]

The less-than-complete Fontan is currently viewed as the most favorable balance of nearly normal arterial oxygen saturation and the lowest frequency of effusive complications. [59] Thus, even the so-called "final" stage commonly takes the form of a fenestrated Fontan, in which virtually all of the vena caval blood is routed to the pulmonary arteries.

A solitary hole 4 mm in diameter or multiple holes 2-3 mm in diameter are placed in whatever structure separates the systemic venous pathway from the pulmonary venous pathway. In the latter style, eventual spontaneous closure is the rule; however, some of these patients subsequently develop protein-losing enteropathy and return for catheter or surgical creation of a stable fenestration.

An alternative less-than-complete Fontan involves partial hepatic vein exclusion. One hepatic vein, typically the left anterior hepatic vein, can be excluded from the systemic venous pathway when the baffle is placed. This excluded hepatic vein drains into the pulmonary venous pathway. Unfortunately, most patients with partial hepatic vein exclusion eventually return with right hepatic vein–to–left hepatic vein collaterals.

Cardiac transplantation

Cardiac transplantation is considered for patients who have undergone the Fontan operation and have developed serious complications and for patients whose hemodynamics make them poor candidates for Fontan operation.

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Outpatient Monitoring

Following each stage of surgical reconstruction, echocardiographic and Doppler evaluation of hemodynamic adequacy should be performed.

After the Fontan operation, monitor for hepatic and biliary dysfunction (ie, measure prothrombin time [PT], gammaglutamyltranspeptidase [GGT], and factor VIII), [32]  supraventricular arrhythmias (Holter monitoring), short stature, and protein-losing enteropathy (monitor fecal alpha1-antitrypsin level). A focus of intensive research is the identification of particularly informative serum biomarkers. [60, 61]

If possible, perform morphologic assessment of the systemic and pulmonary venous pathways and the pulmonary artery architecture, as well as measurement of cardiac index, using MRI or cardiac catheterization.

Should effusive complications, which are common in the early period after a Fontan procedure, recur months or years later, a comprehensive search for a surgically correctable cause should be undertaken. Examples of such correctable etiologies are late-onset pulmonary venous obstruction and thrombosis of the left pulmonary artery.

Only after mechanical obstructions are ruled out should a classic protein-losing enteropathy workup be initiated.

Pulse oximetry that is lower than expected likely indicates the development of decompressing venous collaterals, micropulmonary arteriovenous fistulas, or baffle leaks within the Fontan lateral tunnel.

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