Single Ventricle Workup

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

Laboratory Studies

No specific laboratory blood tests are required in the preoperative workup for single ventricle, although, in the near future, affordable whole-genome sequencing will likely be helpful.

Pulse oximetry or an arterial blood gas (ABG) measurement is frequently helpful in distinguishing between cases of single ventricle with severe pulmonary stenosis and those of single ventricle with arch obstruction, aortic stenosis, or both. For example, when prostaglandin E1 has not been administered, a partial pressure of oxygen (PaO2) of greater than 50 mm Hg lessens the likelihood that a newborn with single ventricle has significant pulmonary stenosis. However, this PaO2 is perfectly consistent with the presence of arch obstruction.

Following Fontan operation, fecal alpha1-antitrypsin measurement is crucial in surveillance for the complication of protein-losing enteropathy (PLE). Abnormalities in serum total protein and albumin are relatively late clues to PLE; because the liver is the sole site of endogenous albumin production, a low serum albumin level signifies the liver's inability to compensate for poor protein intake or excessive protein loss. Prolongation in the prothrombin time (a measure of hepatic synthetic function), [54] abnormally elevated gammaglutamyltranspeptidase, and a reduction in alkaline phosphatase levels (largely a reflection of osteoblastic activity in preadolescent children) are likely early clues to hepatic dysfunction, biliary dysfunction, and reduced bone formation, respectively. [43]

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Imaging Studies

Two-dimensional echocardiography and Doppler analysis

Two-dimensional echocardiography is diagnostic for single ventricle. The presence or absence of pulmonary outflow tract stenosis, aortic arch obstruction, and aortic stenosis is easily delineated. The particular atrioventricular connection and ventriculoarterial alignment is also revealed in a straightforward manner.

The two most common forms of single ventricle are L-looped single left ventricle (LV) with transposition of the great arteries and subpulmonary stenosis (see the image below) and D-looped single LV with transposition of the great arteries and subpulmonary stenosis. The third most common form is L-looped single LV with transposition of the great arteries and aortic arch hypoplasia. The fourth most common form is D-looped single LV with normally aligned great arteries (ie, aorta from LV and pulmonary artery from outlet chamber), which is sometimes referred to as a Holmes heart.

Cranially angulated frontal angiogram of an L-loop Cranially angulated frontal angiogram of an L-looped single left ventricle (LV). ao = aorta, mpa = main pulmonary artery, oc = outlet chamber (rudimentary right ventricle).

In single LV with transposition of the great arteries and aortic arch obstruction, the (sub)aortic stenosis that frequently coexists is due to a narrowing at the communication between the LV and the rudimentary right ventricle (outlet chamber). See the image below. This orifice is frequently referred to as a bulboventricular foramen or outlet foramen.

Long axial oblique-equivalent subcostal echocardio Long axial oblique-equivalent subcostal echocardiogram of single left ventricle (vent) with narrow communication (unlabeled arrow) between the left ventricle and outlet chamber (oc). L = left, lav = left atrioventricular valve, P = posterior, rav = right atrioventricular valve, S = superior.

Echocardiography prior to initial surgery

This study is used for evaluation of the following:

  • Initial identification of single ventricle

  • Presence or absence of pulmonary outflow tract stenosis

  • Presence or absence of aortic arch obstruction

  • Presence or absence of narrowing of communication between normal-sized ventricle and rudimentary ventricle (bulboventricular foramen or ventricular septal defect)

  • Presence or absence of straddling AV valve (ie, the AV valve closer to the outlet chamber having attachments to the rim of the outlet foramen or actually within the outlet chamber): The presence of such attachments should be an absolute contraindication to surgical enlargement of the outlet foramen which might otherwise be contemplated in cases of late-onset "subaortic stenosis."

  • Presence or absence of atrioventricular valve regurgitation, which would have to be palliated prior to Fontan operation

  • Presence or absence of proximal pulmonary artery distortion

  • Ventricular performance

Echocardiography prior to hemi-Fontan (or bidirectional Glenn) operation

This study is used for evaluation of the following:

  • Presence or absence of proximal pulmonary artery distortion, either congenital or created inadvertently by prior pulmonary artery surgery

  • Presence or absence of bilateral superior vena cavas

  • Ventricular performance

Chest radiography

Chest radiography findings vary. In cases with pulmonary stenosis, the cardiac silhouette is normal to mildly enlarged. Pulmonary vascularity is not increased. In cases with arch obstruction, the cardiac silhouette is usually at least mildly enlarged. Pulmonary vascularity usually is increased.

Electrocardiography

Common findings include septal q wave in the right precordial leads (in cases of L-looped single LV) and a monotonous R/S pattern over the anterior precordium.

Holter monitoring

This is useful after a hemi-Fontan operation (or bidirectional Glenn operation) and is particularly helpful after a Fontan operation for surveillance of supraventricular arrhythmias, [55]  sick sinus syndrome, and conduction block.

Magnetic resonance imaging

This study is used for evaluation of the following:

  • Anatomy: Static, steady-state free precession (SSFP) bright blood images; double-inversion, dark blood images; half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences

  • Physiology: Stack of cines (short axis of ventricle, to analyze ventricular performance), cines of systemic venous pathway and pulmonary arteries

  • Velocity mapping of superior vena cava, inferior vena cava, branch pulmonary arteries, and aorta

  • Post–gadolinium injection, three-dimensional reconstruction, and viability imaging

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Procedures

Cardiac catheterization is utilized for evaluating candidacy for Fontan operation, characterizing post-Fontan hemodynamics, and managing supraventricular arrhythmic complications. Interventional correction (balloon angioplasty or endovascular stenting) of pulmonary artery stenosis, recoarctation of the aorta, and embolization of collaterals vessels has become the procedure of choice in most patients. 

Postcatheterization precautions include hemorrhage, vascular disruption after balloon dilation, pain, nausea and vomiting, and arterial or venous obstruction from thrombosis or spasm.

Complications may include rupture of blood vessels, tachyarrhythmias, bradyarrhythmias, and vascular occlusion.

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