ackground :The idipathic hypertrophic cardiomyopathy(HCM) is characterized by inappropriate myocardial hypertrophy of unknwn cause. It may presents a variety of clinical and morphologic features according to the site and extent of the
hypertrophy.
The
widespread
application of echocardiography has made it possible to diagnose HCM earlier and easier,
even in asymptomatic patients. However, clinical reports on the relationship between the
distribution of left ventricular hypertrophy (LVH) and the clinical features are few in Korea.
Therefore, the present clinical study was performed to characterize more completely the
distribution of LVH and to determine whether different patterns of hypertrophy are of
particular clinical significance.
Methods : The clinical, electrocardiographic and echocardiographic features were reviewed
in 32 patients with idipathic HCM of Chonnam National University Hospital from July 1983 to
August 1992.
Results :
1) There were 23 males and 9 females. The mean age was 45.4±16.5 ranging from 15 to
74 years. There were no significant difference in age distribution according to the patterns of
LVH.
2) Based on M-mode and 2-dimensional echocardiographic findings, The 32 patients were
divided into 2 groups; 16 patients in the obstructive HCM group and the other 16 patients in
the non-obstructive HCM group. Among the 16 patients with non-obstructive HCM, there
were 6 patients with asymmetric septal hypertrophy(septal HCM), 7 patients with apical
hypertrophy (apical HCM), 3 patients with symmetric (concentric) hypertrophy (symmertric or
concentric HCM).
3) The cardinal clinical symptoms were dyspnea (71.9%), chest pain (59.5%),
palpitation(37.5%) and syncope(12.5%). There were no significant difference in the fequency of
symptoms according to the patterns of LCH.
4) On chest X-ray examination, the enlargement of cardiac silhoutte (C/T ratio≥0.55) was
observed in 32% of the cases. There wedre 4 patients with C/T ratio≥0.6, and all had
obstructive HCM.
5) In conventional 12 leads electrocardiograms, abnormal electrocardiographic findings were
obtained in 94% of the cases. Among them repolarization abnormalities and left ventricular
hypertrophy were most common, occring in 80.6% and 64.5%, respectively. This was followed
by abnormal Q waves (37.5%), atrial fibrillation (29.0%) and giant T wave inversion (29.0%).
Giant T wave inversion was significantly more common in patients with apical HCM than in
any other patients.
6) On the M-mode echocardiograms, the ratio of left ventricular septal thickness to left
ventricular posterior wall thickness(LVS/LVPW) was 1.58±0.36 in obstructive HCM, 1.55±
0.08 in septal HCM, 1.05±0.14 in apical HCM, and 1.13±0.08 in symmetric HCM.
7) On the 2-dimensional echocardiograms, the ventricular septum and anterolateral free
wall were significantly thicker compared to left ventricular posterior wall in patients with
obstructive and septal HCM (p<0.001, p<0.01 respertively). The apical wall was significantly
thicker compared to the other regions in patients with apical HCM.
8) Mital regurgitation was detected by Doppler echocardiography in 13 (40.6%) of the total
32 cases of HCM and especially in 11 (68.8%) of the 16 cases with obstructive HCM.
9) Continuous wave Doppler echocardiography of left ventricular outflow tract was
performed in 10 patients with obstructive HCM and revealed a mean peak pressure gradient
of 50.1±39.9 mmHg (13∼130 mmHg) between the left ventricular (LV) mid cavity and the
LV outflow tract.
Conclusion : Clinical features are very similar in every patterns of LVH. But the above
results suggested that depnedingon the extent and distribution of LVH, the functional and
morphologic features of HCM may differ considerably. It is still questionable whether
identifiable patterns of hypertrophy are of clinical significance.
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