Isolated left ventricular apical hypoplasia in a young child

Abstract

A 16-month-old, healthy, asymptomatic male child presented with a diagnosis of dilated cardiomyopathy. Cardiovascular examination and chest radiograph were normal. ECG revealed sinus rhythm, and the augmented vector left lead showed raised ST segment, T wave inversion and q waves. Echocardiography showed a globular left ventricle with notched cardiac apex, abnormal echogenicity in the left ventricular apical myocardium, single papillary muscle and normal biventricular function. Cardiac MRI scan revealed a globular left ventricle with fibrofatty changes and retraction of the apex, the papillary muscles closely approximated, and the right ventricle wrapping around the apex of the left ventricle. This is described as isolated left ventricular apical hypoplasia. Diagnosis of this rare entity can be made by MRI, and it has been diagnosed largely in adults. The pathophysiology and long-term outcomes are unknown. We characterise the echocardiography findings of this rare anomaly in a child for the first time in the literature.

Background

Congenital anomalies of the heart usually manifest as structural abnormalities. Localised abnormalities of the myocardium are rare and usually not identified due to lack of specific descriptive information. These abnormalities are underdiagnosed or misdiagnosed and often labelled as generalised cardiomyopathies. In third-world countries, lack of access to healthcare precludes early diagnosis and any worthwhile follow-up of unusual anomalies. Therefore, we report this rare cardiac anomaly which has been largely reported in adults and usually diagnosed by MRI. We desire to bring forth and characterise this anomaly by describing the echocardiography findings along with the MRI findings, so that this anomaly may be diagnosed in children on echocardiography alone.

Case presentation

An asymptomatic 16-month-old male child presented to our tertiary level paediatric cardiac centre with a diagnosis of dilated cardiomyopathy detected on screening. The parents gave a history of noting ‘the heart beating faster than usual’ for the last few months. The child had no breathlessness nor fatigability. He was diagnosed of dilated cardiomyopathy and was given an unfavourable prognosis. In view of the same, the apprehensive parents brought the child for a second opinion. Clinical examination revealed a healthy, playful child, of New York Heart Association (NYHA) class I and with age-appropriate growth and development. He had a normal heart rate and rhythm, blood pressure, and four-limb oxygen saturation by pulse oximetry. Systemic examination of the cardiovascular system was normal.

Investigations

The child was investigated afresh. His chest radiograph showed a normal-sized cardiac shadow and normal lung fields. The bony structures were normal. His haemogram, renal function tests, liver function tests, brain natriuretic peptide, blood sugar, blood pH and serum electrolytes were normal. An ECG revealed sinus rhythm and counter-clockwise depolarisation suggestive of a dominant right ventricular forces; specifically, the augmented vector left lead showed elevated ST segment, T wave inversion and deep q waves. Echocardiography showed a globular left ventricle (LV) with a notched cardiac apex. The left ventricular apical septum as well as its free wall showed abnormal hypodense echogenicity in relation to the normal myocardium. The LV had a single papillary muscle as against two in a normal LV; however, the mitral valve leaflet structure was normal with no valvular stenosis nor regurgitation. The left ventricular ejection fraction was 55% by the Simpson’s biplane method. There were no other congenital structural cardiac defects (figure 1, video 1). In view of these unusual findings, a cardiac MRI scan was carried out on a 3T GE MRI scanner with balanced steady-state free precession cine images, selected ‘black blood’ images and selected phase contrast flow images. Three-dimensional gadolinium contrast-enhanced magnetic resonance angiography was also carried out. The MRI study revealed the following (table 1):

Figure 1.

Transthoracic echocardiography apical four-chamber view of a globular left ventricle (LV) with a notched apex (block arrow). The right ventricle is seen enveloping the left ventricle (thin arrows). IVS, interventricular septum; RV, right ventricle.

Video 1.

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DOI: 10.1136/bcr-2020-239297.video01

Table 1.

Cardiac volumes indexed to the body surface area and the Z-scores of the patient on MRI scan

	End diastolic volume (mL)	End systolic volume (mL)	Stroke volume (mL)	Ejection fraction (%)	Cardiac output (L/min)
LV absolute volumes	29	14	15	50	1.2
Indexed volume Body surface area 0.49 m2	59	28.5	30.6	50	2.4
Z-scores	−0.11 24.19–35.53	1.43 8.45–15.15	−1.46 14.17–22.25	–	−2.56 1326.12–2556.03

LV, left ventricle.

• Longitudinal shortening and horizontal widening of the LV, leading to a spherical LV.

• Retracted apex is noted with heterogeneous signal intensities with chemical shift artefact in keeping with fatty invagination at the apex.

• Close approximation of the papillary muscles due to above, leading to a single papillary muscle appearance.

• Right ventricle wrapped around the LV apex.

• Good biventricular systolic function (figure 2, videos 2 and 3).

Figure 2.

Cardiac MRI (A) axial and (B) coronal views with globular left ventricle with fibrofatty changes in the apical region (block arrow). The right ventricle is seen wrapping around the left ventricular apex (thin arrows).

Video 2.

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DOI: 10.1136/bcr-2020-239297.video02

Video 3.

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DOI: 10.1136/bcr-2020-239297.video03

The cardiac chamber volumes were calculated on MRI scan and are shown in table 1. The cardiac output was less than 2 Z-scores.¹

Differential diagnosis

There are a myriad of differential diagnoses for conditions with abnormal myocardium. One possibility is a local apical myocardial dysplasia which has been replaced by fibrofatty tissue; however, this sounds merely descriptive and does not convey any aetiopathological nor clinical information. Another possibility is secondary cardiomyopathy by infiltration which may be part of a systemic disorder, as in inborn errors of metabolism (IEM).² Children with IEM have associated multisystem involvement, such as hepatic, musculoskeletal or neurological abnormalities. A detailed clinical evaluation usually directs towards an IEM. A cardiac MRI showing uniform late gadolinium enhancement of the myocardium is diagnostic of a generalised cardiomyopathy. Our patient had an isolated focal non-progressive myocardial abnormality with no other systemic involvement. The echocardiography and MRI findings were comparable. The description of the cardiac anomaly matched the description from reported cases of left ventricular apical hypoplasia. Therefore we concluded that our patient had an isolated left ventricular apical hypoplasia.

Treatment

Isolated left ventricular apical hypoplasia is a rare congenital anomaly. No treatment is warranted in asymptomatic cases like our patient. Other reports in adult patients have described clinical features of left ventricular dysfunction akin to dilated cardiomyopathy. Therefore management with cardiac decongestants is reserved only for symptomatic patients.

Outcome and follow-up

The patient has been on follow-up for 5 years and continues to be asymptomatic and of NYHA class I. Echocardiography has not revealed any progression of the abnormal myocardium to a healthy myocardium. His left ventricular ejection fraction is 55%.

Discussion

This unusual anomaly of the myocardium has been described as isolated left ventricular apical hypoplasia. It has been described vividly in case reports of adults.^{3 4} The adult patients were all symptomatic, with the most common symptom being congestive cardiac failure and pulmonary hypertension. There has been one patient presenting with atrial flutter along with low cardiac output.⁵ On the other hand, there have been only three case reports of this anomaly in children aged 3 months, 9 years and 11 years.^6–8 All these children were asymptomatic, with no follow-up data available. The rarity of this condition precludes knowledge of its pathophysiology and natural history. Therefore no extrapolation is possible regarding the likely course in these patients. The diagnosis of this entity has been based on MRI findings so far, and description on echocardiography even in adults is scanty. Cardiac MRI provides vivid images that demarcate the pathological areas from a healthy myocardium. MRI allows tissue characterisation that demarcates a normal myocardium from fibrofatty tissue. However, it is an expensive and time-consuming investigation and often requires general anaesthesia in children. Therefore, we describe the echocardiographic features of this anomaly such that a diagnosis may be reached by echocardiography alone and avoid MRI for the same in children. We characterise the findings on echocardiography as the following:

• Globular LV with a notched cardiac apex.

• Abnormal apical hypodense echogenicity in relation to the normal myocardium.

• Single or closely approximated papillary muscles of the LV.

Patient’s perspective.

I was devastated when I was told that my son had a dilated cardiomyopathy which is incurable and he might need a heart transplant in near future. God!! He looks so normal. That’s when I decided to get a second opinion. The second time he was evaluated, the diagnosis was still unclear but the doctor reassured me that it was not a dismal condition. After an echocardiography, we were advised an MRI scan to confirm the diagnosis. I was still apprehensive till the MRI report was available. Once the diagnosis of isolated left ventricular apical hypoplasia was established, we were concerned about the future course of the disease. We were again reassured by the doctor that it is most likely going to have a benign course. Now he has been on follow up for about five years and he is just the same. The cardiac condition has not deteriorated. I feel very relieved and pray that he doesn’t ever have any complications of his cardiac condition.

Learning points.

• Isolated left ventricular apical hypoplasia is a rare congenital myocardial disease that can present in childhood.

• It is possible to diagnose it on echocardiography alone and cardiac MRI may not be required for diagnosis and follow-up.

• Asymptomatic patients need to be followed up for any evolving symptoms that may suggest myocardial dysfunction or arrhythmias.