Relationship between blood pressure variables (Systolic Blood Pressure, Diastolic Blood Pressure, Pulse Pressure, and Mean Arterial Pressure) and left atrial measurements among hypertensive subjects in a Tertiary Hospital in South-South Nigeria

Aiwuyo Osarume Henry; Ejiroghene Martha Umuerri; Aisosa Ogbomo; John Osaretin Osarenkhoe; Austine Osemwegie Obasohan

doi:10.4103/jcpc.jcpc_16_22

ORIGINAL ARTICLE

Year : 2022 | Volume : 11 | Issue : 3 | Page : 64-68

Relationship between blood pressure variables (Systolic Blood Pressure, Diastolic Blood Pressure, Pulse Pressure, and Mean Arterial Pressure) and left atrial measurements among hypertensive subjects in a Tertiary Hospital in South-South Nigeria

Aiwuyo Osarume Henry¹, Ejiroghene Martha Umuerri¹, Aisosa Ogbomo², John Osaretin Osarenkhoe³, Austine Osemwegie Obasohan²
¹ Department of Medicine, Division of Cardiology, Delta State University Teaching Hospital, Oghara, Nigeria
² Department of Medicine, Division of Cardiology, University of Benin Teaching Hospital, Edo, Nigeria
³ Department of Medicine, Cardiology Unit, Igbinedion University Teaching Hospital, Edo, Nigeria

Date of Submission	15-Apr-2022
Date of Decision	31-Aug-2022
Date of Acceptance	10-Sep-2022
Date of Web Publication	21-Nov-2022

Correspondence Address:
Consultant Cardiologist John Osaretin Osarenkhoe
Department of Medicine, Cardiology Unit, Igbinedion University Teaching Hospital, Edo
Nigeria

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jcpc.jcpc_16_22

Abstract

Background: Hypertension is known to impact significant changes on the heart causing left ventricle diastolic dysfunction which precedes a sequel of anatomical and functional changes in the left atrium. Since hypertension remains the leading cause of diastolic dysfunction in the heart, it is expedient to determine how changes in the blood pressure of patients relate to measures of left atrial (LA) indices. Aims and Objectives: to determine how changes in blood pressure parameters relate to measures in LA indices. Materials and Methods: The study was a descriptive cross-sectional appraisal of 200 hypertensive patients and 100 normotensive controls (matched for age and sex in a 2:1 ratio) using electrocardiography and echocardiography. Participants were recruited from the cardiology clinics in Delta State University Teaching Hospital (DELSUTH), Oghara. Results: The mean age of the study population was 58.7 ± 13.96 (58.42 ± 13.29 for hypertensives and 59.26 ± 15.27 for controls) years, while the median age was 59 years. The female-to-male ratio was 1.06 among cases and 1.27 among the controls. The LA size (volumes and linear diameter) was significantly larger in the hypertensive group compared to the control arm. LA maximum volume correlated significantly with average systolic blood pressure, pulse pressure, and mean arterial pressure. LA pre A wave volume and LA minimum volume correlated significantly with average systolic blood pressure and pulse pressures. Conclusion: Hypertensive patients have larger LA volumes than normotensive controls. The size of the left atrium relates positively with blood pressure variables.

Keywords: Blood pressure, echocardiograph, left atrial diameter, left atrial enlargement, left atrial volume, mean arterial pressure

How to cite this article:
Henry AO, Umuerri EM, Ogbomo A, Osarenkhoe JO, Obasohan AO. Relationship between blood pressure variables (Systolic Blood Pressure, Diastolic Blood Pressure, Pulse Pressure, and Mean Arterial Pressure) and left atrial measurements among hypertensive subjects in a Tertiary Hospital in South-South Nigeria. J Clin Prev Cardiol 2022;11:64-8

How to cite this URL:
Henry AO, Umuerri EM, Ogbomo A, Osarenkhoe JO, Obasohan AO. Relationship between blood pressure variables (Systolic Blood Pressure, Diastolic Blood Pressure, Pulse Pressure, and Mean Arterial Pressure) and left atrial measurements among hypertensive subjects in a Tertiary Hospital in South-South Nigeria. J Clin Prev Cardiol [serial online] 2022 [cited 2023 Jun 9];11:64-8. Available from: https://www.jcpconline.org/text.asp?2022/11/3/64/361691

Introduction

Left atrial (LA) enlargement has been proposed as a predictor of common cardiovascular outcomes including death.^[1] Hypertension is known to cause left ventricle (LV) hypertrophy which leads to myocardial fibrosis and alterations in calcium activation of contractile proteins. This ultimately leads to LV diastolic dysfunction. The persistent diastolic filling impairment will result in the impairment of blood flow from left atrium to LV. This will then result in atrial remodeling, even in patients with mild hypertension because the left atrium possesses a thin wall and it is subject to elevated pressures within the LV causing deformation in structure and dilatation. This fact is shown by the presence of LA enlargement on the electrocardiography (ECG) and/or echocardiography, even before the development of overt hypertensive left ventricular hypertrophy.^[2]

Radionuclide scintigraphic and Doppler echocardiographic imaging modalities of the atria have revealed a high prevalence of impaired early diastolic filling without systolic dysfunction in hypertensive patients.^[2] The diastolic filling can be attributed to factors such as impaired relaxation, stiffness, preload, afterload, and atrial function. The enlargement of the left atrium has been documented even in patients without LV hypertrophy.^[3]

LA size in hypertensive patients with electrocardiographic left ventricular hypertrophy has been shown to be influenced by gender, age, obesity, systolic blood pressure, and left ventricular geometry (eccentric) independently of left ventricular mass and the presence of mitral regurgitation or atrial fibrillation.^[4] Among patients with mild-to-moderate hypertension in a study by Savage et al., only 5% of them were found to have abnormal LA dimensions. They evaluated subjects with diastolic hypertension and did not find an increased prevalence of LA enlargement among hypertensive subjects.^[5] This study seeks to determine the relationship between LA size and blood pressure variables, for example, systolic, diastolic, pulse, and mean arterial pressures.

Materials and Methods

Two hundred adult hypertensive subjects attending the cardiology outpatient clinic at the Delta State University Teaching Hospital (DELSUTH) were recruited for this study, irrespective of blood pressure control, and whether or not they were on antihypertensive medications.

One hundred apparently healthy controls (drawn from hospital workers, visitors, and patient relatives) without any known medical or cardiovascular disease who were 18 years and above and normotensive were recruited for the study. They were matched against the test subjects for age and sex in a 1:2 ratio.

Ethical approval was obtained from the Health Ethics and Research Committee of the DELSUTH, Oghara Delta State.

Informed consent was obtained from participants and was duly signed/thumb printed before they were co-opted for the study. Confidentiality and the right to exit from the study at any time were maintained.

At each examination, systolic and diastolic blood pressure readings were measured with an Accoson mercury sphygmomanometer with the subjects seated and well rested. Blood pressure was taken from both arms and the arm with the higher value was used for that participant. The pulse rate of the participants was also taken. Systolic and diastolic blood pressure readings were determined by the first and fifth Korotkoff phases, respectively. Where the fifth Korotkoff was not heard, the fourth Korotkoff was used as the value of the diastolic pressure. Furthermore, pulse pressure (systolic minus diastolic) and mean arterial pressure (1/3 pulse pressure plus diastolic pressure) were calculated.

A transthoracic echocardiogram (Xario diagnostics ultrasound system model SSA-660A, Toshiba Medicals) with ECG gating was performed according to established recommendations.^[6] The M-mode, two-dimensional, and spectral Doppler and tissue Doppler echocardiographic images were acquired from standard echocardiographic views (parasternal and apical) with all subjects in the left lateral decubitus position.

LA dimension was measured according to the American Society of Echocardiography, from the leading edge of the posterior aortic wall to the leading edge of the posterior wall of the left atrium at end-systole.^[6] Adebayo et al. found a value of 3.1 ± 0.47 (2.16–4.04 cm) for LA linear diameter among normal healthy controls.^[7] This value was used to define the normal LA linear dimension.

LA maximum volume (just before mitral valve opening at the peak of the T-wave on ECG), LA minimal volume (at mitral valve closure at the QRS complex of the ECG), and LA pre “a” wave volume (onset of P wave on ECG) were measured using the biplane Modified Simpson's method of discs. The views for this method were apical four and two chambers. Accurate tracings were made to avoid overestimation. The LA appendage and the pulmonary veins were not included in the tracings.

All volumes were indexed to body surface area. LA enlargement is defined as a maximum LA indexed volume ≥29 mL/m² (normal = 16–28 mL/m², mild enlargement = 29–33, moderate enlargement = 34–39 mL/m², and severe enlargement ≥40 mL/m²), and LA volume (normal = 18–58 ml, mild enlargement = 59–68 ml, moderate enlargement = 69–78 ml, and severe enlargement = ≥79 ml) according to the ASE guidelines,^[6] however, for the purpose of this study, normal LA maximum volume was defined as mean LA maximum volume ± 2 standard deviation using the value from the control arm of the study.

A semi-structured interviewer-administered questionnaire (open- and closed-ended) was used to obtain information on sociodemographic as well as clinical characteristics from all study participants.

Results

As shown in [Table 1] there was a statistically significant difference between systolic blood pressure (<0.001), diastolic blood pressure (<0.001), pulse pressure (<0.001), and mean arterial pressure (<0.001) between cases (hypertensive) and controls.

Table 1: Demographic and clinical parameters of study population

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There was a significant statistical difference in LA linear diameter (P ≤ 0.001), LA maximum volume (P ≤ 0.001), LA pre A wave volume (P ≤ 0.001), LA minimum volume (P ≤ 0.001), LA total emptying volume (P ≤ 0.001), LA expansion index (P = 0.032), LA active emptying volume (P ≤ 0.001), and a fraction (P ≤ 0.001) among the hypertensive and control groups see [Table 2].

Table 2: Echocardiographic left atrial indices of the study population (cases versus controls)

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Left ventricular mass correlates significantly with LA pre A wave volume (P = 0.033) but no correlation was found between specific cardiac indices and LA linear diameter.

Pulmonary systolic velocity (SV) (P = 0.009), pulmonary diastolic velocity (DV) (P = 0.003), and pulmonary systolic time velocity integral (STVI) (P = 0.017) correlated with LA linear diameter. Furthermore, pulmonary SV (P = 0.007), pulmonary DV (P = 0.002), and pulmonary STVI (P = 0.012) correlated with LA maximum volume [Table 3].

Table 3: Correlation between cardiac indices and left atrial dimensions in cases with left ventricular systolic and diastolic dysfunction

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Among hypertensive patients, LA maximum volume correlated significantly with average systolic blood pressure (P = 0.015), pulse pressure (P = 0.045), and mean arterial pressure (P = 0.018). LA Pre A wave volume and LA minimum volume correlated significantly with average systolic blood pressure (P = 0.020), (P = 0.012) and pulse pressure (P = 0.016), (P = 0.012), respectively.

Among the controls, LA maximum volume correlated significantly with average systolic blood pressure, average diastolic blood pressure, pulse pressure, and mean arterial pressure (P < 0.001) (P = 0.022) (P = 0.006) (P < 0.001), respectively. Pre A wave volume correlated significantly with average systolic blood pressure, average diastolic blood pressure, pulse pressure, and mean arterial pressure (P < 0.001) (P = 0.004) (P = 0.014) (P < 0.001), respectively, and minimum volume correlated significantly with average systolic blood pressure, average diastolic blood pressure, pulse pressure, and mean arterial pressure (P < 0.001) (P = 0.009)(P = 0.004) (P < 0.001), respectively [Table 4].

Table 4: Relationship between blood pressure and left atrial measurements among cases

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Discussion

The prevalence of LA enlargement in the hypertensive group was found to be 16% and 59% using LA linear diameter and LA maximum volume, respectively. This prevalence is in keeping with a systematic review done by Cuspidi et al. that found the prevalence of echocardiographic LA enlargement to vary between 16% and 83%, the studies applied both LA linear diameter and LA maximum volume for LA size measurement.^[8]

In another study done in Italy among 164 outpatients with mild-to-moderate hypertension who had not been on antihypertensive medications for at least 3 weeks, the prevalence of LA enlargement was 35% in elderly and 24% in young patients.^[9] However, the diagnosis of left atrial enlargement was based on a single LA dimension obtained from M-mode echocardiography, representing the anteroposterior diameter. This may not reflect LA volume in all patients, especially if LA enlargement occurs asymmetrically.

The incidence of LA enlargement by Doppler echocardiography was found to be 16% in the general population of 2042 residents of Olmsted County in Southern Minnesota ≥45 years of age. They included subjects with cardiovascular conditions such as hypertension, myocardial infarction, congestive heart failure, coronary artery disease, and atrial arrhythmias.^[10] This prevalence approximates that recorded in Nigeria by Adebiyi et al. who found a prevalence of 15.8% in a control-based study with 100 hypertensives and 100 normotensives.^[11] It was hospital based and may not truly represent the general population, unlike the previously mentioned population study.

Adewole et al. in a hospital-based study done in Ibadan, Nigeria, found the prevalence of LA enlargement among newly diagnosed hypertensive subjects to be 15.8% using LA linear diameter.^[12]

There was a statistically significant difference in LA linear dimension between the hypertensive cohort and the control group. Other studies done in Nigeria also showed a significant difference between LA linear diameter among hypertensives and normotensive controls.^[7],[12] However, these studies were done on newly diagnosed patients. Okeahialam et al.^[13] looked at a patient population with similar characteristics (newly diagnosed and those already on antihypertensive medications) with this study. They found no difference between LA linear dimension among hypertensives and normotensive controls.

This study showed that LA maximum volume correlated significantly with average systolic blood pressure, pulse pressure, and mean arterial pressure. LA pre A wave volume and LA minimum volume correlated significantly with average systolic blood pressure and pulse pressure. A similar finding was seen in the Framingham Heart Study^[14] which showed that increased levels of both systolic and pulse pressure were significantly related with increased LA size. However, this correlation was not established for both diastolic blood pressure and mean arterial pressure, especially after controlling for age and body mass index.

Similarly, Adebayo et al.^[7] showed that systolic blood pressure was independently related to LA size. Some other studies, however, did not show an association between LA size and blood pressure parameters (systolic, diastolic, pulse pressure, and mean arterial pressure).^{[12],[15],[16]} The findings of our study may suggest that the association between LA size and blood pressure may be as a result of left ventricular hypertrophy causing increased LV mass (LVM) and not necessarily a direct consequence of blood pressure alone.

The lack of correlation between LA volumes and diastolic blood pressure seen in the hypertensive group may not be very clearly understood, but it is known that diastolic blood pressure relates more with arterial recoil within the vascular bed as opposed to systolic blood pressure which relates more with stroke volume and arterial compliance.

In a Nigerian-based study done by Ogah et al. on the correlates and determinants of LVM in hypertensive individuals, they found that diastolic blood pressure, family history of hypertension, alcohol consumption, LA size, LV wall stress, and tension were the independent predictors of LVM in the hypertensive subjects.^[17] The study, however, showed a correlation between diastolic blood pressures and left ventricular mass.

Bamikole et al.^[18] observed that the mean LAVI increased as the LV diastolic dysfunction deteriorated from impaired relaxation to pseudonormal and restrictive pattern of LV diastolic dysfunction in patients with hypertensive heart disease with or without heart failure.

Adebayo et al.^[7] studied three groups of patients (heart failure patients with preserved ejection fraction, heart failure with reduced ejection fraction, and normal controls) and showed that left ventricular mass was an independent predictor of increased LA size. LA size was highest among those with reduced ejection fraction compared to the other two groups. Adewole et al.^[12] studied hypertensive subjects and showed that LVM was an independent predictor of LA size. In their study, the hypertensive subjects had a significantly thicker septal and posterior wall and a larger relative wall thickness.

Conclusion

Hypertensive patients have larger LA volumes than normotensive controls. The size of the left atrium relates positively with blood pressure variables.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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