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ORIGINAL ARTICLE
Year : 2014  |  Volume : 27  |  Issue : 2  |  Page : 329-335

Role of dobutamine stress echocardiography in the assessment of diastolic reserve in hypertensive patients


1 Cardiology Department, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Cardiology Department, Shebin El-Koum Teaching Hospital, Shebin El-Koum, Egypt

Date of Submission09-Jun-2013
Date of Acceptance08-Sep-2013
Date of Web Publication26-Sep-2014

Correspondence Address:
Mohamed Abdelsalam Mohamed Abulnaga
MBBCh, Cardiology Department, Shebin El-Koum Teaching Hospital, Shebin El-Koum
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1110-2098.141695

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  Abstract 

Objective
The aim of the study was to assess the role of dobutamine stress echocardiography in the assessment of diastolic reserve in hypertensive patients with preserved left ventricle systolic function at rest.
Background
Impaired left ventricular diastolic filling at rest is a common finding in hypertensive patients, especially in those with ventricular hypertrophy, even in the absence of evidence of decreased systolic performance. The stress test may also reveal diastolic dysfunction in patients with normal diastolic function at rest.
Patients and methods
We prospectively identified 30 hypertensive patients, and 20 patients who had no evidence of hypertension served as controls. Left ventricular diastolic function was assessed by dobutamine stress echocardiography using tissue Doppler imaging at rest and during peak stress.
Results
Both patients and controls showed significant increase in systolic function (ejection fraction%) at peak stress, whereas diastolic parameters showed significant changes between patients and controls at rest. E/Ea was significantly higher (P < 0.001) and IVRT was significantly longer (P < 0.001) in hypertensive patients. At peak stress E/Ea was significantly higher (P < 0.001) and IVRT was significantly longer (P < 0.001) in hypertensive patients.
Conclusion
Diastolic stress test could be helpful in patients with unexplained exertional dyspnea who have diastolic dysfunction and normal ejection fraction at rest using conventional and Doppler tissue imaging parameters.

Keywords: Diastolic dysfunction, dobutamine stress echocardiography, hypertension


How to cite this article:
Reda AA, Yassen RE, Abulnaga MA. Role of dobutamine stress echocardiography in the assessment of diastolic reserve in hypertensive patients. Menoufia Med J 2014;27:329-35

How to cite this URL:
Reda AA, Yassen RE, Abulnaga MA. Role of dobutamine stress echocardiography in the assessment of diastolic reserve in hypertensive patients. Menoufia Med J [serial online] 2014 [cited 2019 Nov 14];27:329-35. Available from: http://www.mmj.eg.net/text.asp?2014/27/2/329/141695


  Introduction Top


Hypertension is the most common, readily identifiable, and reversible risk factor for myocardial infarction, stroke, heart failure, atrial fibrillation, aortic dissection, and peripheral arterial disease [1].

Even among patients whose hypertension is assumed to be well controlled by current standard, fewer than one in three is protected from subsequent stroke, myocardial infarction, or heart failure [2],[3].

Impaired left ventricular (LV) diastolic filling at rest is also a common finding in patients with hypertension, especially in those with ventricular hypertrophy, even in the absence of evidence of decreased systolic performance [4].

In many patients with essential hypertension in the absence of coronary artery disease, LV systolic and diastolic function is normal at rest but may respond abnormally during exercise and such patients may develop exertional dyspnea even with good systolic function during exercise [4].

This phenomenon may reflect impaired LV diastolic filling at stress (called lack of diastolic reserve) [5].

Under baseline conditions impaired diastolic reserve is defined as [5]:

  1. No or mild degree of diastolic dysfunction;
  2. Normal filling pressure.


Under stress or during exercise impaired diastolic reserve is defined as:

  1. Overt diastolic dysfunction;
  2. Elevated filling pressure;
  3. Complaints of dyspnea.


Diastolic function reserve index can be calculated as ΔEa × Ea base, where ΔEa is the change of Ea from baseline to exercise and Ea base is early diastolic mitral annular velocity at rest [6].

Many studies have proved that exercise E/Ea and diastolic function reserve index are both associated with exercise capacity, but E/Ea is more closely associated with the expected parameters of diastolic dysfunction [7].

These patients with reduced diastolic reserve can be identified by stress testing [8].

Dobutamine stress echocardiography (DSE) is a standardized method of assessing the systolic and diastolic function of the heart under stress [9].

DSE can be used in hypertensive patients to assess end diastolic pressure and diastolic reserve [10].


  Patients and methods Top


Study participants

The study population included 38 hypertensive patients with a known history of hypertension (on antihypertensive medication) with preserved systolic function at rest, recruited from the outpatient clinic of cardiology from Menoufia University Hospital. Of the 38 patients, eight were excluded because of ischemic changes during stress echocardiography. We also included 20 age-matched and sex-matched individuals to constitute the control group. The study was performed prospectively between January 2012 and February 2013. Participants with a history of coronary artery disease, significant valvular disease, hypertrophic cardiomyopathy, LV systolic dysfunction, atrial fibrillation, history of life-threatening arrhythmias since 1 week, and contraindication for DSE were excluded.

Clinical evaluation

Demographic, medical and drug history, and cardiovascular risk factors were recorded. Hypertension was defined as previous blood pressure recording on two separate occasions of greater than 140 mmHg systolic or greater than 90 mmHg diastolic or the ongoing prescription of antihypertensive medication. Ischemic heart disease was defined as a history of myocardial infarction, unstable angina, or angiographic evidence of more than 50% stenosis of one or more coronary arteries with or without a history of revascularization. Patients underwent physical examination, a 12-lead ECG, chest radiography, and pulmonary function tests.

Echocardiography

Every participant underwent a standard echocardiographic examination and tissue Doppler imaging (TDI) (GE Vingmed Vivid Five Scanner; GE Healthcare, Horten, Norway). Ejection fraction (EF) was measured by M-mode; transmitral flow was used to measure early diastolic wave velocity (E), late-diastolic wave velocity (A) and E/A ratio; and Doppler tissue imaging was used for measurement of mitral annular velocity systolic wave velocity (Sa), early diastolic wave velocity (Ea), late-diastolic wave velocity (Aa), Ea/Aa ratio, E/Ea ratio, isometric relaxation time (IRT), and isometric contraction time (ICT) at rest [Figure 1] and [Figure 2].
Figure 1:

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Figure 2:

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Stress echocardiography

A standard DSE protocol for ischemia was used after discontinuation of B-blockers for 48 h [11]. The test endpoints were target heart rate [0.85 × (220-age)], new or worsening regional wall motion abnormality affecting at least two contiguous segments, ventricular arrhythmias, hypotension, significant ST changes, angina, or severe breathlessness. Atropine was administered if endpoints were not reached. The EF and diastolic mitral inflow variables were measured at rest and at the highest heart rate, where the E and A waves were separately identified [11].

Annular tissue velocity in systole (Sa), early diastole (Ea), and late diastole (Aa) were measured at rest [12]. Sa was measured at peak stress and Ea and Aa at the heart rate at which E and A velocities could be separately measured. Ea/Aa and E/Ea ratios were calculated [8].

Statistical analysis

Data from the patients and controls were collected and subjected to statistical analysis using statistical package for the social sciences (SPSS, version 16; SPSS Inc., Chicago, Illinois, USA) software.

The level of significance was 95%. Thus, P values greater than 0.05 were considered nonsignificant, those less than 0.05 were considered significant, and those less than 0.001 were considered highly significant [13].


  Results Top


This study included 30 hypertensive patients (11 male and 19 female) with a mean age of 53.8 ± 4.1 years and a control group (eight male and 12 female) with a mean age of 51.9 ± 9.7 years.

[Table 1] shows that the prevalence of hypertension was higher among female patients (63.3%) than among male patients (36.7%).
Table 1: Demographic character of studied groups

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As shown in [Table 2], dyslipidemia was the most common risk factor in hypertensive patients, being present in 60% of patients, followed by diabetes (40%) and smoking (26%).
Table 2: Number and percent of risk factors in the patients group

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Comparison of conventional echocardiographic measurements at rest in the studied groups revealed no significant difference between hypertensive patients and controls with respect to early diastolic wave velocity (E), late-diastolic wave velocity (A), E/A ratio, and EF, as shown in [Table 3].
Table 3: Conventional echocardiographic measurements in studied groups at rest

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Resting echocardiography

As shown in [Table 4] there was no significant difference between patients and controls in terms of systolic wave velocity (Sa), late diastolic velocity (Aa), and ICT at rest (P > 0.05).
Table 4: Comparison between resting tissue Doppler imaging measurements in the studied groups

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In contrast, early diastolic velocity (Ea) was highly significantly lower in patients compared with controls (P < 0.001); Ea/Aa was significantly lower in patients than in controls, whereas E/Ea ratio was significantly higher in patients than in controls (P < 0.001).

However, IRT was significantly prolonged in patients than in controls (P < 0.001) [Table 5] and [Table 6].
Table 5: Comparison between conventional echocardiographic measurements in the at peak stress

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Table 6: Comparison between tissue Doppler imaging measurements in the studied groups at peak stress

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Response to stress

Comparison between resting and peak stress conventional echocardiography measurements in the hypertensive patients and control groups [Table 7] and [Table 8] revealed significant increase in EF, late diastolic wave (A) (P < 0.001), and early diastolic wave velocity (E) (P < 0.05) at peak stress in both groups.
Table 7: Comparison between resting and stress conventional echocardiography measurements in the studied patient

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Table 8: Comparison between resting and stress conventional echocardiography measurements in the studied control

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Although there was no significant difference in E/A ratio (P > 0.05) in the control group, E/Ea ratio showed highly significant increase in patients at peak stress.

As shown in [Table 9], comparison between resting and peak stress TDI measurements in the hypertensive patients revealed highly significant increase in systolic wave velocity (Sa) during peak stress (P > 0.05) and highly significant decrease in ICT and IRT during peak stress (P > 0.05). In contrast, there was significant increase in late diastolic wave velocity (Aa) at peak stress (P < 0.05) but no significant changes in early diastolic wave velocity (Ea) and Ea/Aa ratio between rest and peak stress (P < 0.001).
Table 9: Comparison between resting and peak stress tissue Doppler imaging measurements in the studied patients

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Comparison of TDI measurements between rest and peak stress in the control group [Table 10] revealed highly significant increase in systolic wave velocity (Sa) (P < 0.001) and highly significant decrease in ICT (P < 0.001) during peak stress, but significant increase in late diastolic wave velocity (Aa) and early diastolic wave velocity (Ea) during peak stress (P < 0.05). In contrast, there were no significant changes in IRT, E/Aa, and E/Ea between rest and peak stress (P > 0.05) [Table 11]
Table 10: Comparison between resting and stress tissue Doppler imaging in the studied control

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Table 11: Percent of changes in E/Ea ratio at peak stress and rest in patients and control groups

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  Discussion Top


In one-third to one-half of patients diagnosed with congestive heart failure, systolic function of the LV is preserved, indicating that diastolic dysfunction is a major pathophysiological abnormality in these patients [14].

Diastolic dysfunction is highly prevalent, particularly in hypertensive patients [15]. Patients with diastolic dysfunction are susceptible to pulmonary congestion, because the LV end diastolic pressure increases upon mild effort or mild volume overload. This is the major cause of impaired quality of life in patients with diastolic dysfunction. In some patients with diastolic dysfunction, impairment of systolic function also progresses and eventually leads to death. Furthermore, recent epidemiological studies have shown that the prognosis of congestive heart failure patients with normal systolic function is not always better than that of patients with impaired systolic function [16].

In this study we assessed the diastolic function of the heart in two groups that have normal EF (30 hypertensive patients, 11 male and 19 female, with a mean age of 53.8 ± 4.1 years and 20 controls, 8 male and 12 female, with a mean age of 51.9 ± 9.7 years) using conventional echocardiography and TDI during rest and using DSE during peak stress, and we studied the relationship between diastolic function of the heart and diastolic reserve in relation to hypertension.

The present study showed no significant difference in early diastolic wave velocity (E), late diastolic wave velocity (A), and E/A ratio between hypertensive patients and the control group at rest. This result was in agreement with those of Verdecchia et al. [17], who studied 250 patients (145 hypertensive and 105 normotensive patients) and found no significant difference in early diastolic wave (E), late diastolic wave (A), and E/A ratio between the two groups.

In our study we used TDI to measure mitral annulus velocities at the lateral wall because a number of recent studies have noted that, in patients with normal EFs, lateral tissue Doppler signals (E/Ea and Ea/Aa) have the best correlations with LV filling pressures and invasive indices of LV stiffness. These studies favored the use of lateral tissue Doppler signals in this population [18].

In the current study there was no significant difference between patients and controls in terms of systolic wave velocity (Sa) and ICT at rest (P > 0.05). This finding was similar to that of Bruch et al. [19], who studied 10 normal and 15 hypertensive patients and found no significant difference in systolic wave velocity (Sa) between the two groups.

IRT was significantly prolonged in patients than in controls at rest (P < 0.001). This result agreed with that of Avdiæ et al . [20], who studied 64 hypertensive patients (57 with LVH and seven without LVH) and showed that IRT was longer in patients with diastolic dysfunction.

Poulsen et al. [21] studied 40 hypertensive patients and 30 age-matched controls and found that there were no significant changes in late diastolic velocity (A) and late diastolic velocity of the mitral annulus (Aa) between the two groups, similar to the results of the present study.

Burgess et al. [10] studied 37 patients and showed that the ratio of early mitral velocity to early diastolic velocity of the mitral annulus (E/Ea) highly correlated with the LV diastolic pressure measured with catheterization.

Several studies have demonstrated that early diastolic velocity (Ea) decreased and the E/Ea ratio increased with impaired LV relaxation.

Ommen et al. [22] studied 100 patients referred for cardiac catheterization who underwent simultaneous Doppler interrogation. Invasive measurements of LV pressures were obtained and the mean LV diastolic pressure was used as a surrogate for mean left atrial pressure. The result showed that the ratio of mitral velocity to early diastolic velocity of the mitral annulus (E/Ea ratio) had a better correlation with mean LV diastolic pressure than did other Doppler variables for all levels of diastolic function.

In our study there was significant increase in EF% and Sa at peak stress compared with rest in both hypertensive and control groups, whereas there was no significant difference in EF between patients and controls at peak stress, in agreement with the results of Ha et al. [23].

In contrast, there was significant decrease in E/A ratio at peak stress in patients compared with controls, similar to the results of Lamb et al. [24] who studied 11 patients with hypertension and 13 age-matched healthy controls with MRI at rest and with phosphorus magnetic resonance spectroscopy at rest and during high-dose atropine-dobutamine stress, revealing that the E/A ratio decreased in diastolic dysfunction at peak stress.

In the current study there was no significant difference in systolic wave velocity (Sa) and ICT between patients and controls at peak stress.

Early diastolic wave velocity (Ea) showed significant decrease in patients than in controls at peak stress, in contrast to the E/Ea ratio, which increased in patients compared with controls at peak stress. These results agreed with those of Chattopadhyay et al. [8] who studied 41 patients with diastolic heart failure and 29 age-matched and sex-matched individuals who underwent stress echocardiography focusing on diastolic function during rest and peak stress, finding that E/Ea increased during stress in patients compared with controls.

In our study the E/Ea ratio showed significant increase in the hypertensive group at peak stress compared with rest, which agreed with the results of Ha et al. [23], who studied 45 patients, 26 with diastolic dysfunction and 19 with normal diastolic function, and found that the E/Ea ratio increased in the diastolic dysfunction group more than in controls (lack of diastolic reserve).

In patients with diastolic dysfunction, the mitral E/A ratio, annular Ea, was lower than in controls and the E/Ea ratio was higher. These patients have reduced diastolic reserve that can be uncovered by stress testing. However, a reduced mitral E/A ratio in the presence of normal annular tissue Doppler velocities can be seen in volume-depleted normal individuals. Therefore, an E/A ratio should not be universally used to infer the presence of diastolic dysfunction [8], and E/Ea is more closely associated with the expected parameters of diastolic dysfunction [7].

The diastolic stress test may facilitate the attribution of exertional dyspnea to cardiac and noncardiac diseases. However, there is currently no consensus as to the optimal marker of exertional diastolic dysfunction, the main alternative being estimated LV filling pressure (exercise E/Ea) [7].

The increase in E/Ea ratio from rest to stress in hypertensive patients (which means elevated LV filling pressure) may be explained as follows: the stress-induced tachycardia allows less time for relaxation. This is further amplified in hypertensive patients, leading to the inability to generate a higher rate of diastolic relaxation, causing the diastolic filling pressure (E/Ea ratio) to increase.

Thus, the detection of early, subclinical myocardial dysfunction is difficult when using conventional echocardiographic techniques that can evaluate only global systolic or diastolic function. Compared with standard echocardiography, TDI can reveal some more specific parameters (such as E/Ea), and, if these investigations are used in combination with a DSE, myocardial abnormalities, as a response to stress, may be detected [25].


  Conclusion Top


The diastolic stress test is most useful in hypertensive patients (with preserved LV systolic function) with unexplained exertional dyspnea and diastolic dysfunction. This test can detect the diminished diastolic reserve in these hypertensive patients by means of increased E/Ea ratio at stress, which is a parameter of LV filling pressure.

The limitations of this study are the small number of patients and lack of prediction of symptoms, mortality, morbidity, and number of patients having LVH in the study.


  Acknowledgements Top


Conflicts of interest

There are no conflicts of interests.[27]

 
  References Top

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2. Levy D, Larson MG, Vasan RS, Kannel WB, Ho KK. The progression from hypertension to congestive heart failure. JAMA 1996; 275:1557-1562.  Back to cited text no. 2
    
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4. Slama M, Susic D, Varagic J, et al. Diastolic dysfunction in hypertension. Curr Opin Cardiol 2002; 17:368-373.  Back to cited text no. 4
    
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6. Ha JW, Choi D, Park S, et al.0 Left ventricular diastolic functional reserve during exercise in patients with ýmpaired myocardial relaxation at rest. Heart 2009; 95:399-404.  Back to cited text no. 6
    
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22.Ommen SR, Nishimura RA, Appleton CP, Miller FA, Oh JK, Redfield MM, et al. Clinical utility of Doppler echocardiography and tissue Doppler imaging in the estimation of left ventricular filling pressures: a comparative simultaneous Doppler-catheterization study. Circulation 2000; 102:1788-1794.  Back to cited text no. 22
    
23.Ha JW, Oh JK, Pellikka PA, Ommen SR, Stussy VL, Bailey KR, et al. Diastolic stress echocardiography: a novel noninvasive diagnostic test for diastolic dysfunction using supine bicycle exercise Doppler echocardiography. J Am Soc Echocardiogr 2005; 18:63-68.  Back to cited text no. 23
    
24.Lamb HJ, Beyerbacht HP, van der Laarse A, et al. Diastolic dysfunction in hypertensive heart disease is associated with altered myocardial metabolism. Circulation 1999; 99:2261-2267.  Back to cited text no. 24
    
25.Patrascu N. Assessment of systolic and diastolic cardiac function beyond traditional markers in hypertensive patients. Role of cardiac reserve. Maedica (Buchar) 2013; 8:214-219.  Back to cited text no. 25
    
26.Mozaffarian D, Roger VL, Benjamin EJ, et al. Heart disease and stroke statistics - 2013 update: a report from the American Heart Association. Circulation 2013; 127:e6-e245.  Back to cited text no. 26
    
27.Ha JW, Lulic F, Bailey KR, Pellikka PA, Seward JB, Tajik AJ, et al. Effects of treadmill exercise on mitral inflow and annular velocities in healthy adults. Am J Cardiol 2003; 91:114-115.  Back to cited text no. 27
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10], [Table 11]



 

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