Keywords

Single ventricle, double inlet left ventricle, Van Praagh classification, patent ductus arteriosus, true single ventricle, functional single ventricle, univentricular heart

There is an increased prevalence of adults with congenital heart disease (CHD) in the last few years due to better detection using noninvasive echocardiography and cardiac magnetic resonance imaging (MRI). The most common CHD detected is isolated ventricular septal defect. Ventricular septal defect may be associated with a number of other complex CHDs. One such complex CHD is single ventricle wherein both the morphological right and left atrium drain into a single chamber, which may be morphological left ventricle (more common) or morphological right ventricle or into a ventricle with indeterminate morphology. It is usually more common in males. Single ventricle can be easily detected using a 2D echocardiography. Usually prognosis is very dismal without early surgery.

CASE REPORT

A 17-year-old girl, came to our emergency department with features suggestive of drug-induced dystonia, which was managed conservatively. However on examination, she was thin built, moderately nourished and anxious looking patient. General examination revealed mild pallor. There was no cyanosis or clubbing. Vitals were normal. Cardiovascular examination revealed a single second heart sound, with soft systolic murmur in the pulmonary area. Rest of the systemic examination was normal. Electrocardiogram showed normal sinus rhythm with rightward axis deviation. Lead V1 showed a dominant R and large biphasic RS complex in mid-precordial leads (Fig. 1).

Transthoracic echocardiogram revealed situs solitus, two atria’s with an intact interatrial septum, a single ventricle with fine trabeculations and absence of moderator band. A small patent ductus arteriosus (PDA) was seen. We performed 3 Tesla cardiac MRI (Siemens) done with both white blood and black blood imaging, gradient echo cine imaging and contrast-enhanced pulmonary angiogram with time-resolved angiography with stochastic trajectories (TWIST) protocol of Siemens to delineate vessel relationship to chambers. Entire study was completed in approximately 25 minutes, which is considerably less than the time needed for a conventional 1.5 Tesla MRI. Segmental analysis of the MRI revealed normal visceroatrial situs, two atria’s, with intact interatrial septum draining into a common ventricle of left ventricular morphology, with the rudimentary right ventricle (rRV) lying anterior and to the left of the common ventricle (Figs. 2 and 3). There is venoatrial concordance, ventriculoatrial and ventriculoarterial discordance. There is subvalvular pulmonary stenosis. There is no obstruction to the aortic outflow (Figs. 4 and 5). The right atrium measures 3.5 cm, left atrium measures 3.1 cm and common ventricle measures 6.1 cm. Main pulmonary artery is significantly dilated measuring 5 cm. Left pulmonary artery measures 10 mm, and the right pulmonary artery measures 16 mm. Small PDA is present (Fig. 6).

DISCUSSION

Single ventricle is an exceedingly rare and complex CHD. Worldwide incidence of double inlet left ventricle (DILV) is reported as 1% of all congenital heart malformations.1 There is usually a male predominance with sex ratio of 3:1. Single ventricle is classified morphologically by Van Praagh et al into types (A-D). It may be double inlet with left ventricular morphology, absence of right ventricular sinus (type A), double inlet with right ventricular morphology and absence of left ventricular sinus (type B), double inlet with mixed ventricular morphology and absence of ventricular septum (type C) or double inlet ventricle with indeterminate morphology (type D). Great arteries may be normally related (type I or Holmes heart), aorta may be anterior and rightward (type II) or leftward (type III), “inverted” in a posterior and leftward orientation (type IV).2 Our patient has the commonest type of DILV (type A-III) (Fig. 7).

The natural course of the patients with un-operated single ventricle is usually poor. The death rate in a well-formed single ventricle of left ventricular morphology is 4.8% per year, with 70% of them dying before the age of 16. Prognosis is far worse for patients with right ventricular or indeterminate morphology.3 The univentricular heart physiology depends on key factors such as systemic and pulmonary venous return, flow across the AV valves, obstruction to systemic outflow and pulmonary vascular resistance. Pulmonary stenosis has shown to be beneficial for these patients and prevent them from developing pulmonary hypertension early on in their life.4 They exhibit favorable streaming due to the preferential flow of systemic venous blood to the pulmonary artery and pulmonary venous blood to the aorta. Select patients with left ventricular morphology and well-balanced physiology can sometimes survive till late adulthood. They have also been able to successfully complete their families and withstand the physiological derangements during pregnancy. Similar hemodynamic parameters allowed our patient to have good functional capacity with minimal symptoms. Very few of the DILV patients have this kind of favorable circulation, which shows the rarity of this condition.

REFERENCES

1. Franklin RC, Spiegelhalter DJ, Anderson RH, Macartney FJ, Rossi Filho RI, Douglas JM, et al. Double-inlet ventricle presenting in infancy. I. Survival without definitive repair. J Thorac Cardiovasc Surg. 1991;101(5):767-76.
2. Van Praagh R, Ongley PA, Swan HJ. Anatomic types of single or common ventricle in man. Morphologic and geometric aspects of 60 necropsied cases. Am J Cardiol. 1964;13:367-86.
3. Moodie DS, Ritter DG, Tajik AJ, O’Fallon WM. Long-term follow-up in the unoperated univentricular heart. Am J Cardiol. 1984;53(8):1124-8.
4. Ammash NM, Warnes CA. Survival into adulthood of patients with unoperated single ventricle. Am J Cardiol. 1996;77(7):542-4.