Cardiac manifestations in mucopolysaccharoidosis

Abstract

Through this case, we want to highlight, that in patients with mucopolysaccharoidosis (MPS), coronary arteries need to be screened in patients with LV dysfunction. Further, CT scan may not be a good modality and newer diagnostic modalities like IVUS must be offered to delineate concentric obstruction. Also, meticulous screening for hypertension must be carried out in all MPS patients.

A 4-year-old female child presented with coarse facial features, respiratory distress, and abdominal distention. On examination, she had dysmorphic features with large protruding tongue, global delay in milestones, respiratory distress, and abdominal distention (Fig. 1A). Blood pressure was more than 99th centile in all 4 limbs. Respiratory system and cardiovascular examination were normal. Per abdomen examination showed hepatosplenomegaly (Fig. 1A). Chest X-ray and electrocardiography were within normal limits (Fig. 1B and D). Clinical impression was of storage disorder with strong possibility of mucopolysaccharoidosis. The patient's urine tandem mass spectroscopy showed findings consistent with mucopolysaccharoidosis (MPS) VI. Echocardiogram showed severely compromised LV function with EF of 30% and dilated LV chambers (Fig. 1E). The coronary arteries were enlarged on echocardiogram with Z score of 4.5 (arrow in Fig. 1C) but no luminal narrowing of coronaries was noted. The mitral valve appeared thick causing mild mitral regurgitation (Fig. 1F). The aorta on echocardiogram was normal. CT scans confirmed the thickened coronaries without luminal narrowing. On CT aortogram, there was no coarctation seen which was done in view of increased blood pressure revealed no co-arctation of aorta.

Fig. 1.

(A) Clinical photograph of the patient showing short stature, dysmorphic features with large protruding tongue, hepatosplenomegaly, and umbilical hernia. (B) Chest X-ray without significant findings. (C) Basal short axis showing thickened coronaries with Z score of 4.5. No narrowing of coronaries was noted. (D) Electrocardiography within normal limits. (E) M – mode echocardiogram showing severely compromised LV function with ejection fraction of 30% (red circle). (F) Basal short axis image showing thickened mitral valve causing mild mitral regurgitation.

Cardiac involvement may be seen more commonly in MPS I, II, and VI. LV dysfunction is also reported in MPS more commonly second association in frequency after severe MR. However, coronary artery pathology should be ruled out in every patient of MPS. Diffuse intimal proliferation from glycosaminoglycans (GAG) deposition within large epicardial coronary arteries can occur early, especially in rapidly progressing MPS I causing high-grade narrowing.¹ In our patient, there were thickened coronary arteries; however, no luminal narrowing was demonstrated by CT scan. It is reported that the narrowing in MPS is concentric and diffuse so the conventional methods including CT scan may not be a good modality to diagnose coronary artery disease. In adult patients, IVUS-guided coronary angiogram has been used to diagnose coronary artery disease in Fabry's disease, which too causes similar narrowing of coronaries. We offered coronary angiogram in our patient, but the patient's parents consented against this.

Markedly reduced aortic elasticity has been reported in MPS I. This could be attributed to the downstream effects of GAGs on the assembly of tropo-elastin,² resulting in elastin that is both decreased in content and abnormal in structure; this might be the reason for hypertension in our child as all other causes causing hypertension in this age group were excluded.

From this case, we want to highlight that coronary arteries need to be screened for the cause of LV dysfunction, and from review of literature, CT scan may not be a good modality and newer diagnostic modalities like IVUS must be offered to delineate concentric obstruction. Also, meticulous screening and treatment of hypertension must be carried out in all MPS patients.

Conflicts of interest

The authors have none to declare.