|Year : 2015 | Volume
| Issue : 2 | Page : 136-141
The relation of gender and geometry to left ventricular structure and functions in a newly presenting hypertensive population in Nigeria
Abiodun M Adeoye1, Ifeoluwa A Adewoye2, Adewole Adebiyi1, Okechukwu S Ogah2, Akinyemi Aje2, Olulola O Oladapo1, Ayodele O Falase3
1 Department of Medicine, University of Ibadan; Department of Medicine, University College Hospital, Ibadan, Nigeria
2 Department of Medicine, University College Hospital, Ibadan, Nigeria
3 Department of Medicine, University of Ibadan, Ibadan, Nigeria
|Date of Web Publication||30-Jul-2015|
Abiodun M Adeoye
Department of Medicine, University of Ibadan, Ibadan
Source of Support: None, Conflict of Interest: None
Background: Studies differ on the influence of gender and geometry on the functions of left ventricle (LV). We report the relation of abnormal geometry and gender to LV structure and functions in an African population.
Materials and Methods: A total of 156 consecutive newly presenting hypertensives comprising 53% females were enrolled into the study. All participants underwent full clinical evaluation, and echocardiographic examination was performed according to the American Society of echocardiography recommendation. Using LV mass index (LVMI) and relative wall thickness, 145 subjects with complete echocardiographic parameters were divided into four LV geometric patterns; normal, concentric remodelling (CR), eccentric hypertrophy, and concentric hypertrophy.
Results: The mean age of the hypertensive subjects was 59.5 (12.3) years. The mean age and blood pressure (BP) indices were comparable across the gender. While males were taller, females were heavier and had wider waist and hip circumferences. Men had larger left atrium, aortic root diameter, aortic valvular opening, LV dimensions, and LVM compared with females. LV systolic and diastolic functions were similar. More than half of the subjects had abnormal geometry with CR prevalent. The subjects with concentric hypertrophy were the youngest (P = 0.036) and had the highest mean diastolic BP (P = 0.037). There was no significant gender influence on the distribution of geometry pattern. Left Atrial diameter and LV dimensions except posterior wall thickness at diastole were significantly larger in eccentric hypertrophy when compared with other groups (P = 0.0001). LV ejection fraction was lowest among subjects with eccentric hypertrophy. Diastolic function parameters were comparable among the groups.
Conclusion: The study showed that more than half of the study subjects had abnormal geometry even at the presentation. Abnormal geometry probably affects LV systolic function more than the diastolic filling patterns. Prompt management may alter the prognostic effect of abnormal geometry among the study group.
Keywords: Gender, geometry, hypertension, left ventricular function
|How to cite this article:|
Adeoye AM, Adewoye IA, Adebiyi A, Ogah OS, Aje A, Oladapo OO, Falase AO. The relation of gender and geometry to left ventricular structure and functions in a newly presenting hypertensive population in Nigeria. Nig J Cardiol 2015;12:136-41
|How to cite this URL:|
Adeoye AM, Adewoye IA, Adebiyi A, Ogah OS, Aje A, Oladapo OO, Falase AO. The relation of gender and geometry to left ventricular structure and functions in a newly presenting hypertensive population in Nigeria. Nig J Cardiol [serial online] 2015 [cited 2021 Jan 15];12:136-41. Available from: https://www.nigjcardiol.org/text.asp?2015/12/2/136/161777
| Introduction|| |
Hypertension remains a global health challenge and despite all the advances in management, the control of high blood pressure (BP) remains poor. , Uncontrolled BP has been associated with early target organs in brain, kidney, and heart. , The left ventricle (LV) adapts to the various neuro-hormonal and hemodynamic changes in chronic systemic hypertension by undergoing changes in its geometry.  Using left ventricular mass index (LVMI) and relative wall thickness (RWT), four geometric patterns have been identified. These LV geometric patterns include normal geometry (normal LVMI and RWT), concentric remodeling (CR) (normal LVMI and increased RWT), eccentric hypertrophy (increased LVMI and normal RWT) and concentric hypertrophy (increased LVMI and increased RWT). 
Increased LVM and/or abnormal LV geometry have been shown to be independent risk factors for cardiovascular morbidity and mortality.  Furthermore, studies have identified the better prognostic role of geometry compared with LVM.  Untreated abnormal LV geometry progresses to dilated cardiac failure among other pathway, via an interval myocardial infarction.  This has been corroborated in earlier studies, which showed that abnormal LV geometry is associated with increased cardiovascular morbidity due to progressive ischemic compromise, systolic and/or diastolic dysfunction, arrhythmias and sudden cardiac death. ,,, Systemic hypertension, therefore, leads to impairment of both LV systolic and diastolic function due to increase in after load and also to changes in LV geometry and structure.
In this study, we sought to determine the relation of abnormal geometry and gender on LV structure and functions in an African hypertensive population since most of the previous studies were carried out on subjects of European descent and African-Americans. Few data exist in Nigeria population on the combined effect of geometry and gender on the LV structure and functions.
| Materials and methods|| |
This is a cross-sectional study carried out at the Cardiology unit of the University College Hospital (UCH), Ibadan. UCH is the first teaching hospital to be established in Nigeria in 1957 and has over the years grown to an 850 bed hospital with about 60 departments. Out of these, the clinically oriented departments run various clinics spread across the days of the week. The average number of new patients seen per week in the clinics is estimated at about 250. The bed occupancy rates ranges from 55% to 60%.
The subjects comprised of 156 consecutive newly presenting hypertensives seen at the cardiology clinic of the hospital over a 6 months period between January and July 2012. The study was powered at 90% to detect a minimum gender difference of 10 g/m 2.7 in the LVMI. BP was measured with a mercury sphygmomanometer (Accosson London) according to the standard guidelines  Systolic and diastolic BP were measured at Korotkoff sounds phases 1 and V, respectively. Three independent BP measurements were obtained with a minimum interval of 1 min and the last two of three BP was used as the first may have had stress effects that settled once the subject was re-assured and became used to the procedure. Hypertension was then defined as systolic BP ≥ 140 mmHg and/or diastolic BP ≥ 90 mmHg or being on pharmacological treatment. 
Anthropometric measurements including height, weight, waist, and hip circumferences were obtained by trained nurses. Height was measured without shoes to the nearest centimeter while weight was measured to the nearest 0.1 kg on an electronic scale with the subject wearing light outdoor clothing and no shoes. Waist circumference was measured at the highest point of the iliac crest with the subject in light clothing. An informed consent was obtained from each subject. Subjects with fasting plasma glucose of >126 mg/dL and plasma creatinine of >1.5 mg/dL and those that refused consent were excluded from the study. Ethical clearance was obtained from the joint Ethics Committee of the UCH/University of Ibadan.
Echocardiographic examination was performed with the subjects in partial left lateral decubitus position using a Toshiba Xario (Toshiba Medical Systems Corp) with a 3.5 MHz transducer. Two-dimensional guided M-Mode measurements were obtained as recommended by the American society of Echocardiography.  LV, septal, posterior wall thickness and cavity dimensions were measured using leading edge convention at both end-diastole and end-systole. LVM was calculated using the formula of Devereux et al.  This has been shown to yield LVM closely related to autopsy measurements (r = 0.90) and has good inter-observer reproducibility (ρ =0.93) in one study. 
Left ventricular mass was indexed by the allometric power of height (LVM/Ht 2.7 ).  LV hypertrophy was considered present if the LVMI is greater or equal 49.2 g/m 2.7 in males and greater or equal 46.7 g/m 2.7 in females.  RWT was calculated as 2 posterior wall thickness diastole/LV internal diameter diastole. Increased wall thickness was present when RWT > 0.45. LV geometry was stratified using LVMI and RWT. Normal geometry - normal LVMI and RWT, CR - normal LVMI and increased RWT, eccentric hypertrophy-increased LVMI and RWT < 0.45, Concentric hypertrophy - increased LVMI and RWT ≥ 0.45. Ejection fraction was calculated using the formula of Teichholz. 
Trans-mitral flow velocities were obtained with the Doppler sample volume placed just beyond the tip of mitral valve leaflets. The parameters measured were early diastolic peak flow velocity (E), early diastolic flow time (EDFT), late diastolic peak flow velocity (A), the deceleration time of early mitral velocity and the ratio of E to A (E/A). Isovolumic relaxation time was measured with pulse wave Doppler beam intersecting the LV outflow and inflow tracts, EDFT was measured from the onset of diastolic flow to the intersection of a line extrapolated to the baseline and late diastolic flow time was measured from the onset of late diastolic flow to the end of diastolic flow. 
Data were analyzed with the Statistical Package for Social Sciences (SPSS Inc., Chicago, IL, USA) version 15. Results were expressed as either mean values (standard deviation) or proportions (percentage). Comparisons for statistical significance were by independent Student's t-test for continuous variables or Chi-square analysis for categorical variables. One-way analysis of variance with Tukey's post-hoc method was used to compare the demographic and echographic parameters among the various geometric groups. The level of significance level was set at P ≤ 0.05.
| Results|| |
A total of 156 subjects (73 males and 83 females) were recruited. [Table 1] shows the basic characteristics and echocardiographic parameters of the study population. The mean age of the hypertensive subjects was 59.5 (12.3) years. Age and BP measurements were comparable across the gender. While the males were taller, the females were heavier, had wider waist and hip circumferences and higher body mass index. Men had larger left atrium, aortic root diameter, aortic valvular opening, LV dimensions, and LVM when compared with females. LV systolic and diastolic functions were similar across gender. The LV geometry was abnormal in 58% of the subjects with the frequency of CR, concentric hypertrophy, and eccentric hypertrophy in the subjects at 24.8%, 12.4%, and 20.7%, respectively. There was no significant gender influence on the distribution of geometry pattern. [Table 2] shows the demographic features of different geometric pattern. The subjects with concentric hypertrophy were the youngest (P < 0.036) and had the highest mean diastolic BP (P < 0.037). As shown in [Table 3], left atrial diameter (LAD) and LV dimensions except posterior wall thickness at diastole were significantly larger in eccentric hypertrophy when compared with other groups (P < 0.0001). LV ejection fraction was lowest among hypertensive subjects with eccentric hypertrophy. Trans-mitral LV diastolic filling patterns were comparable among the groups.
|Table 1: Basic characteristics and echocardiographic parameters of study population|
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| Discussion|| |
The present study showed that 58% of newly presenting hypertensives in an African population had abnormal LV geometry with CR preponderating. Previous studies have shown that echographic identification of LV geometry is a promising tool to improve on cardiovascular risk stratification in hypertension.  Concentric hypertrophy has been shown to be most independent risk factor for further major cardiovascular events.  The type of LV geometric pattern that preponderates is determined to a large extent by whether pressure or volume overload is predominating.  In addition, ethnicity, environment, and sample sizes account for different frequencies of various LV geometry demonstrated in most of the earlier studies. CR and concentric hypertrophy may predominate in the early stages of hypertension due to the predominating pressure overload whereas eccentric hypertrophy progressively takes over with increased LVM due to increase in volume overload.  Contrary to our findings, Aje et al.  in a controlled study found 72% of hypertensives studied had abnormal LV geometric pattern with concentric hypertrophy predominating. The dissimilarities in the two studies are not clear. The explanation may be because Aje's study population were predominantly men, in contrast to the female preponderance in this study. Male gender is a strong determinant of LV geometry pattern,  although, gender influence on LV structure and functions was not determined in their study.
Apart from the diastolic BP that was lower in eccentric hypertrophy compared with concentric hypertrophy, the systolic BP was similar among the geometric groups. However, the predominance of CR in this study calls for more stringent management to prevent progression into concentric hypertrophy and eventual heart failure. Studies have shown that CR even in the absence of LV hypertrophy double all cause cardiovascular mortality, which is similar to eccentric hypertrophy and is further increased in concentric hypertrophy.  Our finding of predominant CR confirms the earlier observations by other studies. ,,
Gender influence on the LV geometric pattern and functions has been demonstrated by many authors, ,, and the results have not been consistent. In this study, despite the larger weight, body mass index, and waist circumference in females when compared with males, men were found to have larger LAD, LV dimensions, and LVM. This might suggest that male gender has a stronger influence on LV structures and functions than body weight and adiposity. This is similar to the findings in LIFE study  where abnormal LV dimensions and functions in men were attributed to higher incidence of angina pectoris in them, compared with women. Our study contrasted with Kolo et al.'s  study that demonstrated a gender influence on LV geometry proportions. Our findings of nongender influence on geometry proportions agree with another study in the eastern part of Nigeria.  The conflicting report may result from differences in demographic variables in the study populations.
As the alteration in a geometric pattern of the LV progresses, the LV function diminishes. Eccentric hypertrophy results from increased volume over load and can be the terminal stage of hypertensive heart disease with eventual heart failure. In contrast to Sekiya et al.  who reported no differences in the LV systolic function among LV geometric pattern groups, our study showed that participants with eccentric hypertrophy had the lowest ejection fraction, which may suggest the onset of the decline in LV systolic function among this group. This is similar to reports in studies by Akintunde et al.  and Fox et al.  The lack of influence on the diastolic function by the different geometric patterns in this study should be interpreted with caution. Trans-mitral parameters of diastolic function assessment showed no significant differences across the geometric types. However, LAD was larger in eccentric hypertrophy when compared with other groups. Current available data have shown that increased left atrial dimension is a good index of LV diastolic dysfunction. ,, Valocik et al.  demonstrated a stepwise increase in LA sizes as the diastolic functions deteriorate from impaired relaxation to pseudo normalization pattern and eventual restrictive physiology. A similar study from south western Nigeria, also found increased LAD among the eccentric hypertrophy group.  While this has generated a research focus to explore, this subtle effect of geometry on LV diastolic function cannot be ignored. Probably, the diastolic filling abnormality would have been evident if the latest method of assessment were implored.
Due to small sample size in this study, the findings may not be generalizable to the whole population, more so that some of the participants have been on treatment prior to presentation, which could lead to misclassification of the geometry. However, similarity of our findings with other larger studies especially those in the same communities as ours lay credence to the reproducibility of our study.  Furthermore, nonuse of more current methods to assess LV function such as mid-wall systolic function, tissue Doppler or other evolving methods is a drawback. This proffer opportunity for future comparative studies as equipment with current methods of assessment becomes more available in the country.
| Conclusion|| |
The study showed that more than half of hypertensive subjects at presentation had existing abnormal geometry. Abnormal geometry probably affects LV systolic function more than the diastolic function. Male gender is a strong predictor of LV dimensions and functions, but gender has no effect on geometry distribution. Early diagnosis and prompt management of hypertension may alter the prognostic effect of abnormal geometry among the study group. There is a need for a larger prospective study with a long time follow-up in Africa.
| Acknowledgment|| |
We acknowledge the role of Dr. Mayowa Owowlabi, Consultant Neurologist in the Department of Medicine University College Hospital for his precious contribution to the conceptualization of the study and the useful suggestions from the review of the manuscript. Furthermore, we appreciate the role of Mr. Victor Ilivieda, our Research Assistant in the recruitment of study participants, data entry and typing of the manuscript.
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[Table 1], [Table 2], [Table 3]