EVALUATION OF LEFT VENTRICLE DIASTOLIC FUNCTION IN NATIVE HYPERTENSIVE PATIENTS. Cardiovascular Medicine Department, Cairo University ABSTRACT Background: Systemic hypertension is a common cause of left ventricle (LV) diastolic dysfunction. However, its prevalence in native hypertensive patients is unknown. Objective: To determine prevalence of LV diastolic dysfunction in never-treated hypertensive patients using Doppler trans-mitral inflow and propagation velocity (VP) of the early filling wave on M-mode colour Doppler. Methods: Two-dimensional echocardiography including Doppler was performed on 160 newly diagnosed cases of systemic hypertension and 40 age and sex matched controls. Pulsed wave Doppler trans-mitral inflow and propagation velocity of the early filling wave on M-mode colour Doppler for assessment of diastolic dysfunction were performed. Results: The mitral E/A ratio differed significantly between native hypertensive patients and controls (0.7+0.1 and 1.2 ±0.1respectively, P<0.001). Colour M-mode propagation velocity was reduced in native hypertensive patients compared to controls (45±3.2and55±2.3cm/s, p value <0.001). Conclusion: Our study showed that LV diastolic dysfunction is common in newly diagnosed never-treated hypertensive patients. Moreover, effort should be made to screen for them in order to start the appropriate treatment. Key words: colour M-mode propagation velocity, diastolic dysfunction, systemic hypertension. INTRODUCTION Systemic hypertension is a major public health problem and an important cause of morbidity and mortality (1). Diastolic dysfunction is the commonest functional alterations that occur in left ventricle (LV) it is common in elderly 95
women than men (2). The clinical significance of LV diastolic dysfunction as a cause of heart failure with normal systolic function in patients with hypertension is well recognized (3). Doppler echocardiography is an important non-invasive and an easily reproducible method of evaluating and follow-up of hypertensive patients with diastolic dysfunction (4). Most of the studies of LV diastolic dysfunction in systemic hypertension have been on chronic patients already on medical treatment. The current study used pulse-wave Doppler trans-mitral inflow and propagation velocity of the early filling wave on M-mode colour Doppler to determine the prevalence of LV diastolic function in newly diagnosed hypertensive patients. METHODS Hundred and sixty newly diagnosed never-treated hypertensive patients aged 54±14 years and 40 age-and-sex-matched controls underwent standard echo-doppler study. Hypertension was defined as persistent elevation of blood pressure above 140/90 mmhg on two or more occasions with the patient in a sitting position for at least five minutes (1). The study protocol was approved by Ethical Review Committee, and a written informed consent was obtained from all those who participated in the study. Patients were subjected to history taking, physical examination and demographic parameters including waist circumferences (WC) and Body mass index (BMI). ECHOCARDIOGRAPHY Echocardiography studies were performed using a commercial scanner (ie33; Philips Medical System, USA) according to the recommendations of the American Society of Echocardiography (5). The LV dimensions, ejection fraction and left atrium diameters were calculated. Left ventricle diastolic function was assessed using mitral inflow velocities (E and A wave), E wave deceleration time and iso-volumetric relaxation time. From the apical fourchamber view, the Colour Doppler sector map of the mitral inflow was adjusted 96
to obtain the longest column of colour flow from the mitral annulus to apex. The M-mode cursor was placed through the centre of this flow, avoiding boundary regions. The colour M-mode flow propagation velocity (Vp) was measured as the slope of the first aliasing velocity during early filling from the mitral valve plane to 4 cm distally into the LV cavity. Propagation velocity <50cm/s was considered to detect abnormal LV diastolic function (6). (Figure 1) (a) (b) Figure 1: Trans-mitral flow propagation velocity (Vp) in a control participant (a) and in hypertensive patient (b). Statistical analysis: All statistical calculations were done using computer program SPSS (Statistical Package for the Social Science; SPSS Inc., Chicago, IL, USA) release 15 for Microsoft Windows (2006). All Data were statistically described in terms of mean standard deviation ( SD). Comparison of numerical variables between the study groups was done using Student t test for independent samples. P values less than 0.05 was considered statistically significant. RESULTS Hundred and sixty newly diagnosed never-treated hypertensive patients aged 54.8±14 years (112Females/ 48 Males)and 40 controls aged 54.6±12 years old 97
(32 Females/8 Males) were enrolled in the study.sixty percentage of the study group were diabetics(n=112).baseline demographic and clinical characteristics are shown in Table 1 Table 1: Demographic and clinical characteristics of the study population Variables Hypertensive group Control group P value Age (years) 54.8 ±14 54. 6±12 NS Gender 112F/ 48 M 32 F/8 M 0.409 BMI kg/ m2 33.3±7.4 25.9±7.2 <0.001 SBP mm hg 152.7±9.7 129.4±8.068 <0.001 DBP mm hg 95.2±5.04 78.35±6.960 <0.001 BMI: Body mass index, DBP: Diastolic blood pressure, SBP: Systolic blood pressure, NS: non-significant. Plus-minus values are means ±SD. Echocardiography parameters: The interventricular septum thickness, LV diastolic diameters and left atrium diameters are increased in the newly diagnosed hypertensive group. However, the fraction shortening (FS) was not different between the patients and controls. (Table 2) Table 2: Echocardiography parameters in study groups Variables Systemic hypertension Controls ANOVA P value IVSD, (cm) 1.1±0.1 0.8±0.1 0.000* LVDd, (cm) 4.8±0.6 4.6±0.4 0.075 FS, % 30.4±3.8 33.4±4.9 0.014 LAD, (cm) 4.2±0.5 3.4±0.2 0.000* IVSd: Interventricular septal thickness in diastole, LVDd: Left ventricular dimension in diastole, FS: Fractional shortening, LAD: Left atrium dimensions, are means ± SD * Statistical Significance 98 plus-minus values Mitral E-wave and the E/A ratio were greater in the controls (73.9±3.6 cm/s and 1.2 ±0.1) than in the hypertensive group (62.9±10.0 cm/s and 0.8±0.1) with p value< 0.001. Deceleration time was significantly prolonged in hypertensive
group (270.6 ±47.1versus 156.5±7.5 ms in control group, P value <0.001). The commonest type of diastolic dysfunction in newly diagnosed hypertensive patients was the impaired relaxation pattern.. Colour M mode propagation velocity was significantly different between controls and hypertensive patients (55±2.3 and 45.3 ±3.2 cm/s respectively, p value <0.001). (Figure2) Figure 2: Colour M mode propagation velocity in the study groups. DISCUSSION The current study showed that LV diastolic dysfunction is common in never-treated hypertensive patients with normal LV systolic function. Prevalence of diastolic dysfunction mainly in the form of impaired relaxation pattern was 80 %( n=128) Kingue et al (7) in a study in black Africans untreated hypertensive population in Cameroon reported prevalence of (67%). However, Balogun et al (8) reported a lower prevalence of 46% in their study on hypertensive patients. The selection and the characteristics of those patients might have accounted for the lower prevalence in their study. The current study is concordant with Ike et al (9) who reported impaired relaxation prevalence of 82.86% and discordant with others (10) who reported 99
lower prevalence of 18.6% (32 out of 198) in their newly diagnosed hypertensive population. Oyati et al (11) had alluded to the fact that the poor state of the economy is among the factors militating against hypertension presenting early for cardiac evaluation. The propagation velocity (Vp) of the early filling wave on M-mode color Doppler allows qualitative estimation of left ventricular relaxation. In contrast with the E wave on Pulsed Doppler, Vp is relatively independent of atrium pressure, so that the pattern of normal filling can be distinguished from that of pseudo normal filling (12). Therefore, colour M-mode propagation velocity have provided useful insights in the assessment of diastolic function and have been shown to provide an accurate estimate of LV relaxation (13). It seems to be relatively insensitive to the effects of preload (14). Concordantly we found that colour M mode propagation velocity was significantly reduced in hypertensive patients (45.3 ±3.2 versus 55±2.3 cm/s in controls, P value< 0.001). Colour M mode propagation velocity has been shown to correlate with deaccleration time (DT) in hypertensive patients (14) The current study showed that DT was significantly prolonged in native hypertensive group compared to the controls (270.6 ±47.1 versus 156.5±7.5 ms respectively) CONCLUSION The current study showed that LV diastolic dysfunction is common in native hypertensive patients not on medical treatment. Moreover, LV diastolic dysfunction occurred in newly diagnosed hypertensive patients without LV hypertrophy; hence its early detection may lead to additional risk stratification and may guide the choice of antihypertensive drugs. 100
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