Cardiovascular Journal of Africa: Vol 28 No 1 (January/February 2016)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 28, No 1, January/February 2017

AFRICA

been reported. The second interesting abnormality was the

PM. It has been suggested that isolated PM hypertrophy is

a possible variant of HCM, but only a few cases have been

reported in the literature.

3-6

Some of these patients presented with

electrocardiographic findings, such as high left precordial voltage

and inverted T waves, especially those with posteromedial

PM hypertrophy.

3,5

In our case, hypertrophy and malposition

occurred at the anterolateral PM.

Treatment of HCM is based on the anatomical abnormality.

In a subset of patients with HCM, LVOT obstruction will be

present not only because of septal hypertrophy, but also owing

to muscular apposition created by the abnormal PM. Failure to

recognise this anomaly would not relieve the obstruction.

In our case, aside from the abnormal PMand IVS, the chordae

tendineae connecting them with the mitral valve also contributed

to the crowded LVOT. Pre-operative identification of these three

contributors to LVOT obstruction altered the surgical strategy.

Therefore, this patient underwent septal myectomy of the sharp

angle, partial PM resection in the LVOT, as well as removal of

the abnormal chordae tendineae. Excessive PM resection could

have caused mitral valve insufficiency, which may have resulted

in the need for mitral valve replacement or surgical mitral leaflet

manipulation. Fortunately, the saline injection test showed only

trivial mitral valve regurgitation.

Redaelli

et al

proposed a procedure to reposition the

anterior PM followed by adjunctive implantation of a complete

semi-rigid mitral ring to abolish the systolic anterior motion and

residual mitral insufficiency. If our patient had had moderate to

severe mitral regurgitation, a semi-rigid mitral ring or even mitral

valve replacement would have been considered.

Conclusion

Different mechanisms causing LVOT obstruction may occur in

subgroups of patients with HCM. The mechanism of this rare

LVOT obstruction resulted from focal basal IVS hypertrophy and

angulation deformity, and abnormality of the PM and chordae

tendineae. Although we did not have genetic evidence, this

abnormal combination may represent a gap in our knowledge

of HCM. Careful echocardiographic and other radiological

assessment is needed before surgery, which could change the

diagnosis and management of HCM.

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Fig. 3.

Histological examination showed inflammation (A, black arrows), cardiomyocyte hypertrophy and disarray (B, *), as well as

interstitial fibrosis (B, white arrows) (haematoxylin and eosin, ×100). At the two-month follow up, transthoracic echocardiog-

raphy demonstrated a LVOT gradient of 23 mmHg (C).