An early systolic sound associated with midventricular obstruction in a patient with hypertrophic cardiomyopathy

Effect of cibenzoline on regional left ventricular function in hypertrophic obstructive cardiomyopathy

BACKGROUND

Cibenzoline, a class Ia antiarrhythmic drug, can be used to relieve left ventricular (LV) outflow obstruction in hypertrophic obstructive cardiomyopathy (HOCM). However, the mechanism of this agent in HOCM has been controversial.

HYPOTHESIS

This study was designed to investigate the effect of cibenzoline on regional LV function and the acoustic properties in HOCM using ultrasonic integrated backscatter.

METHODS

Ten patients with HOCM and 16 healthy volunteers were examined. In patients with HOCM, wall thickening (%WT) and the magnitude of cyclic variation of integrated backscatter (mag-CVIBS) in the interventricular septum (IVS) and LV posterior wall were measured before and after oral administration of cibenzoline. To assess asynchrony of contractile elements, the phase difference between CVIBS and %WT were measured from the LV posterior wall. Pressure gradients at the LV outflow tract were estimated using continuous-wave Doppler echocardiography.

RESULTS

Although %WT decreased significantly in the LV posterior wall, %WT and mag-CVIBS remained unchanged in the IVS. The phase difference in the LV posterior wall was significantly greater in patients with HOCM than in healthy volunteers (HOCM:healthy volunteers, 1.57 +/- 0.23:1.00 +/- 0.03, p < 0.001) at baseline. After administration of cibenzoline, the phase difference shifted to normal value (from 1.57 +/- 0.23 to 1.28 +/- 0.27, p = 0.0382), and pressure gradients at the LV outflow tract decreased (from 109 +/- 55 to 58 +/- 48 mmHg, p = 0.0063). Changes in pressure gradients at the LV outflow tract and the phase difference were closely related.

CONCLUSIONS

Regional function and the acoustic properties of myocardium in HOCM were altered by cibenzoline in the LV posterior wall but remained unchanged in the IVS. The normalization of the phase difference in the LV posterior wall was closely related to the decrease in pressure gradients at the LV outflow tract. These findings suggest that negative inotropic action and the improvement of asynchrony in the LV posterior wall rather than in the IVS may contribute to the reduction of pressure gradients at the LV outflow tract in HOCM.

Beneficial Effect of Cibenzoline on Left Ventricular Pressure Gradient With Sigmoid Septum

An 83-year-old woman with hypertension was admitted to hospital with episodes of dyspnea on effort after having breakfast. Physical examination revealed a systolic murmur at the left sternal border in the third to fourth intercostal space. Cross-sectional echocardiography showed a sigmoid-shaped interventricular septum markedly protruding into the left ventricle, concentric left ventricular hypertrophy, systolic anterior motion of the mitral valve, and a resultant left ventricular outflow tract obstruction with a pressure gradient of 121.8 mmHg. She began daily treatment with 60 mg metoprolol. However, the chest symptoms were not relieved and the left ventricular outflow tract obstruction was still visible on echocardiography. She was then given 200 mg daily of cibenzoline, in addition to 40 mg metoprolol, and the left ventricular pressure gradient significantly decreased and she was free of symptoms without any complications. This case shows that cibenzoline may be useful in the treatment of left ventricular outflow tract obstruction caused by sigmoid septum.

Attenuation of biventricular pressure gradients by cibenzo-line in an 18-year-old patient with hypertrophic obstructive cardiomyopathy

An 18-year-old male patient with biventricular hypertrophic obstructive cardiomyopathy (HOCM) had successful reduction of the pressure gradients by cibenzoline. At 11 months after birth, he was first diagnosed with cardiac murmurs and by the age of 5 years, he was diagnosed with subpulmonic infundibular stenosis with a pressure gradient of 10 mmHg by cardiac catheterization. At the age of 14, re-catherterization revealed hypertrophic cardiomyopathy with isolated obstruction of the right ventricular outflow tract, with a pressure gradient of 70 mmHg, but no obstruction in the left ventricle. He began daily treatment with 30 mg propranolol. At the age of 18, he was admitted for cardiac evaluation. An echocardiogram revealed left mid-ventricular and subpulmonic obstructions associated with pressure gradients of 88 mmHg and 65 mmHg, respectively. A single oral dose of 200 mg of cibenzoline decreased the pressure gradients in the left and right ventricles (38 mmHg and 36 mmHg, respectively). He was then given 300 mg daily of cibenzoline, and both pressure gradients remained low without any complications 8 months later at the time of discharge.

Hypertrophic cardiomyopathy with midventricular obstruction and apical aneurysm: a case report

A 71-year-old woman had hypertrophic cardiomyopathy associated with midventricular obstruction and an apical aneurysm in the left ventricle. She had had abnormal electrocardiograms for more than 30 years and for the past year had been suffering from occasional attacks of dizziness and low systemic blood pressure. Holter 24-h electrocardiographic monitoring revealed ventricular paroxysmal contractions (676/day) with nonsustained ventricular tachycardia. Doppler echocardiography revealed paradoxical jet flow from the apical aneurysm to the left ventricular outflow during early diastole. Magnetic resonance imaging depicted midventricular hypertrophy and a dyskinetic thin apical wall, which were confirmed by angiography. Coronary angiograms showed no narrowing of the major extramural coronary arteries, but there was compression of aberrant coronary arteries apparently feeding the hypertrophic portion of the left ventricular wall. Stress thallium-201 myocardial imaging showed a persistent severe defect in the left ventricular apex. A hemodynamic study revealed low cardiac output and an intraventricular pressure gradient (approximately 90 mmHg) between the left ventricular apical high-pressure chamber and the subaortic low-pressure chamber. The present case represents a rare combination of hypertrophic cardiomyopathy, midventricular obstruction, and an apical aneurysm in an elderly woman. Myocardial ischemia may have played an important role in the genesis of the apical aneurysm.

Antiarrhythmic drug, cibenzoline, can directly improve the left ventricular diastolic function in patients with hypertrophic cardiomyopathy

The effect of cibenzoline on left ventricular diastolic function was investigated in patients with hypertrophic cardiomyopathy (HCM). Before and 2 h after an oral administration of 200 mg of cibenzoline, echocardiographic, apexcardiographic and gated radionuclide angiographic studies were performed in 12 patients with hypertrophic obstructive cardiomyopathy (HOCM) and 7 with hypertrophic nonobstructive cardiomyopathy (HNCM). After administration of cibenzoline, the left ventricular pressure gradient decreased from 96+/-33 mmHg to 29+/-22 mmHg (<0.0001). Fractional shortening decreased from 53.3+/-7.5 to 45.4+/-6.2% (p=0.0008) in patients with HOCM and from 49.9+/-8.7 to 40.9+/-7.5% (p=0.0039) in patients with HNCM. On the other hand, E-wave velocity increased and A-wave velocity decreased in both groups. The time between the second heart sound and O point was shortened from 253+/-53 to 176+/-21 ms (p<0.0001) in patients with HOCM and from 245+/-54 to 185+/-44 ms (p=0.0050) in patients with HNCM. The time to peak filling rate was shortened from 248+/-79 to 190+/-40 ms (p=0.0072) in patients with HOCM and from 218+/-33 to 163+/-26 ms (p=0.0052) in patients with HNCM. These results indicate that in patients with HCM, cibenzoline suppresses left ventricular systolic function, but can markedly improve left ventricular diastolic dysfunction through its direct action.