Discussion

We report a young child presenting in cardiogenic shock with echocardiogram findings consistent with takotsubo cardiomyopathy secondary to severe anoxic brain injury related to pneumococcal meningitis.

Takotsubo cardiomyopathy, also known as stress-induced cardiomyopathy, is a form of severe, typically transient, left ventricular systolic dysfunction in the absence of coronary artery disease. It is mostly encountered in post-menopausal women following traumatic emotional or physical injury/stress; however, it has been described in all ages.

The revised Mayo Clinic Criteria for the diagnosis of takotsubo cardiomyopathy in adults include the following:

1. 1. Transient hypokinesis, akinesis, or dyskinesis of the left ventricular mid-segments with or without apical involvement; the regional wall motion abnormalities extend beyond a single epicardial vascular distribution, and a stressful trigger is often, but not always, present.

2. 2. Absence of obstructive coronary disease or angiographic evidence of acute plaque rupture.

3. 3. New electrocardiographic abnormalities (either ST-segment elevation and/or T-wave inversion) or modest elevation in cardiac troponin level.

4. 4. Absence of pheochromocytoma and myocarditis. ^{Reference Medina de Chazal, Del Buono and Keyser-Marcus1}

The findings on our patient’s echocardiogram, particularly the pattern of dysfunction with relatively preserved basal myocardial contractility with mid and apical hypokinesis/akinesis, are typical of takotsubo cardiomyopathy. ^{Reference Medina de Chazal, Del Buono and Keyser-Marcus1} Treatment is supportive, and recovery of left ventricular function is expected. Fulminant myocarditis was also considered, and the patient did receive treatment with intravenous immunoglobulin. However, troponin, which is typically pronounced in the setting of myocarditis, was only minimally elevated, and the electrocardiogram was quite unremarkable. Studies including endomyocardial biopsy and cardiac MRI, which can aid in diagnosing myocarditis, were not employed due to the increased risk of invasive/lengthy procedures in this unstable patient. In this instance, the specific findings on the echocardiogram made takotsubo cardiomyopathy the most likely diagnosis and further invasive studies or unnecessary treatment were deferred.

Takotsubo cardiomyopathy is a rare finding in children with favourable cardiac prognosis. ^{Reference Serrano, Schamberger and Parent2} Several case reports have been published in children with similar echocardiogram findings in the setting of severe neurologic injury. ^{Reference Serrano, Schamberger and Parent2–Reference Wittekind, Yanay, Johnson and Gibbons9} The included Table 1 outlines these cases. The median duration to recovery was 6.5 days, similar to our case. Of note, only three cases met three or more Mayo Clinical Criteria, highlighting the difficulty in applying adult criteria to children. All patients recovered with supportive care, in some cases requiring mechanical circulatory support.

Table 1. Case reports of children with takotsubo cardiomyopathy associated with brain injury. NR, not reported

In our case, the diagnosis of takotsubo cardiomyopathy was made in the setting of pneumococcal meningitis with severe anoxic brain injury. The pathogenesis of takotsubo cardiomyopathy has been ascribed to high levels of circulating catecholamines, oversaturating cardiac adrenergic receptors leading to increased oxygen demand and myocyte hypoxia. Subsequent metabolic changes during hypoxia include uncoupling of electron transport, affecting ATP synthesis. Release of oxygen-derived free radicals interferes with calcium and sodium transporters, compounding injury to the myocardium. It has been hypothesised that the regional differences in myocardial dysfunction may be explained by the differences in density of beta-1 and beta-2 adrenergic receptors in the apex versus the base of the heart. ^{Reference Lyon, Rees, Prasad, Poole-Wilson and Harding10}