The Effect of Dobutamine Stress on Left Ventricular Outflow Tract Gradients in Hypertensive Patients with Basal Septal Hypertrophy

Abstract

Basal septal hypertrophy (BSH), a cause of left ventricular outflow tract (LVOT) obstruction, is thought to occur by increased ventricular dynamics. The aim of the study was to evaluate the effect of pharmacologic stress on LVOT gradients in a group of hypertensive patients with BSH. Dobutamine stress was used in 24 hypertensive patients (mean age 56 ±8 years; 11 women) with BSH and 20 normal controls (mean age 54 ±9 years; 7 women). Ejection fraction and myocardial mass, basal septal dimension, and LVOT diameter were measured with 2-dimensional echocardiography. LVOT velocities and transmitral velocities before and at peak dobutamine infusion were determined by continuous wave Doppler and pulsed Doppler, respectively. There were no differences in mean ejection fraction and myocardial mass between BSH patients (58 ±3%, 204 ±24 g) and normals (56 ±4%, 201 ±32 g). The basal septum was thicker in patients (1.55 ±0.2 cm) than in normals (1.03 ±0.1 cm, p<0.001). Maximum LVOT velocities were similar in BSH (1.2 ±0.4 m/sec) and normals (1.1 ±0.2 m/sec) at rest. At peak stress, maximum LVOT velocities were higher in BSH (3.3 ±0.6 m/sec) than normals (1.7 ±0.4 m/sec, p<0.001). LV rate-pressure product at peak stress was higher in BSH (23,326 ±4,388) than normals (17,592 ±2,409, p<0.001). LV isovolumetric relaxation time was prolonged, and the E/A ratio was decreased in the patients at rest (130 ±14 msec and 0.72 ±0.18, respectively, p<0.001). At peak stress, diastolic function did not significantly change in two groups. The correlations between LVOT velocity change by stress and mean LVOT diameter (r =-0.668, p<0.001) and mean BS thickness (r =0.610; p<0.001) were significant in the whole group. High velocities appeared on LVOT at peak pharmacologic stress in the hypertensive patients with BSH compared with control group. This suggests dynamic ventricular ejection by stress may contribute to hypertrophy of the basal segment, which is the closest part of septum to increased afterload.

Get full access to this article

View all access options for this article.

References

Levine RA , Vlahakes GJ , Lefebvre X , et al : Papillary muscle displacement causes systolic anterior motion of the mitral valve: experimental validation and insights into the mechanism of subaortic obstruction. Circulation 91:1189-1195, 1995.

Qin JX , Shiota T , Lever HM , et al : Left ventricular out flow tract area measured by real-time 3D echocardiography in hypertrophic obstructive cardiomyopathy. J Am Soc Echocardiogr 12:202M, 1999.

Pearson AC , Gudipati CV , Labovitz AJ : Systolic and diastolic flow abnormalities in elderly patients with hypertensive hypertrophic cardiomyopathy. J Am Coll Cardiol 12:989-995, 1988.

Come PC , Bulkley BH , Goodman ZD , et al : Hyper-contractile cardiac states simulating hypertrophic cardiomyopathy. Circulation 55:901-908, 1977.

Deligonul U , Uppstrom E , Penick D , et al : Dynamic left ventricular outflow tract obstruction induced by pericardial tamponade during acute anterior myocardial infarction. Am Heart J 121:190-194, 1991.

Aurigemma G. Battista S , Orsinelli D , et al : Abnormal left ventricular intracavitary flow acceleration in patients undergoing aortic valve replacement for aortic stenosis: A marker for high postoperative morbidity and mortality. Circulation 86:929-936, 1992.

Bartunek J , Vanderheyden M , de Bruyne B : Dynamic left ventricular outflow tract obstruction after anterior myocardial infarction: A potential mechanism of myocardial rupture. Eur Heart J 16:1439-1442, 1995.

Haley JH , Lawrence JS , Tajik AJ , et al : Dynamic left ventricular outflow tract obstruction in acute coronary syndromes: An important cause of new systolic murmur and cardiogenic shock. Mayo Clin Proc 74:901-906, 1999.

Nishida K , Saito T , Kamijima G , et al : Echocardiographic findings of the “sigmoid septum” and its clinical implication. J Cardiography 10:873-879, 1980.

10.

Fukuda N , Asai M , Tominaga T , et al : Noninvasive studies of dynamic left ventricular outflow obstruction in patients with sigmoid septum. J Cardiography 14:445-457, 1984.

11.

Middlehoff CJ , Becker AE : Ventricular septal geometry: A spectrum with clinical relevance. In: The Ventricular Septum of the Heart, ed. by Wenink et al. Boston: Martinus Nijhoff, 1981, pp 9-22.

12.

Henein MY , O'Sullivan C , Sutton GC , et al : Stress-induced left ventricular outflow tract obstruction: A potential cause of dyspnea in the elderly. J Am Coll Cardiol 30:1301-1307, 1997.

13.

Pellikka PA , Oh JK , Bailey KR , et al : Dynamic intraventricular obstruction during dobutamine stress echocardiography: A new observation. Circulation 86:1429-1432, 1992.

14.

Grossman W , Jones D , McLaurin LP : Wall stress and patterns of hypertrophy. J Clin Invest 56:56, 1975.

15.

Tunick PA , Gindea A , Kronzon I : Effect of aortic valve replacement for aortic stenosis on severity of mitral regurgitation. Am J Cardiol 65:1219-1221, 1990.

16.

Yalçin F , Shiota T , Odabashian J , et al : Comparison by real-time three-dimensional echocardiography of left ventricular geometry in hypertrophic cardiomyopathy versus secondary left ventricular hypertrophy. Am J Cardiol 85:1035-1038, 2000.

17.

Yalçin F , Tsujino H , Greenberg N , et al : Real-time three-dimensional echocardiographic evaluation of mitral annular characteristics in myocardial hypertrophy. Eur Heart J 291:1599, 1999.

18.

Smart SC , Knickelbine T , Malik F , et al : Dobutamineatropine stress echocardiography for the detection of coronary artery disease in patients with left ventricular hypertrophy. Circulation 101:258-263, 2000.

19.

Krasnow N : Subaortic septal bulge simulates hypertrophic cardiomyopathy by angulation of the septum with age, independent of focal hypertrophy. An echocardiographic study. J Am Soc Echocardiogr 10:545-555, 1997.

20.

Croazatier EB : Mechanical adaptation to ventricular overloads: Experimental studies in the stiu heart. In: Cardiac Hypertrophy and Failure, ed. by Swynghedauw B. London: Inserm/John Libbey Eurotext, 1990, pp 317-323.

21.

Badke FR , Cowell JW : Early changes in left ventricular regional dimensions and function during chronic volume overloading in the conscious dog. Circ Res 45:420-428, 1979.

22.

Maron BJ , Edwards JE , Epstein SE : Disproportionate ventricular septal thickness in patients with systemic hypertension. Chest 73:466-470, 1978.

23.

Farias CA , Garcia MJ , Rodriguez L , et al : Effects of residual gradient after aortic valve replacement by St Jude valve on left ventricle regression mass in patients with aortic stenosis. J Am Soc Echocardiogr 12:102G, 1999.

24.

LeGrice IJ , Takayama Y , Covell JW : Transverse shear along myocardial cleavage planes provides a mechanism for normal systolic wall thickening. Circ Res 77:182-193, 1995.