| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
From the Department of Obstetrics and Gynaecology, Chinese University of
Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong.
Correspondence to Prof Christopher J. Haines, Department of Obstetrics and Gynaecology, Prince of Wales Hospital, Shatin, New Territories, Hong Kong. E-mail cjohnhaines{at}cuhk.edu.hk
Methods and Results—Measurements of
endothelium-dependent and
endothelium-independent vascular reactivity were
compared in 2 groups of women treated with a GnRHa for 6 months. One
group received estrogen/progestogen add-back therapy during the second
3 months of GnRHa treatment. Vascular reactivity was examined by use of
ultrasound measurements of changes in brachial artery diameter.
Endothelium-dependent changes were assessed during
reactive hyperemia, whereas
endothelium-independent changes were measured after the
administration of glyceryl trinitrate sublingual spray. Treatment with
the GnRHa alone had an inhibitory effect on
endothelium-dependent relaxation. However,
endothelium-dependent relaxation significantly improved
in the group receiving add-back therapy (14.6%) compared with the
group treated with GnRHa alone (8.6%) (P<0.01). There
were no significant endothelium-independent changes in
either group.
Conclusions—These results suggest that the administration of
add-back therapy has a protective effect on vascular function in
GnRHa-induced hypoestrogenism. As a model for the menopause, these
results also suggest that the long-term administration of hormone
replacement therapy would result in
endothelium-dependent arterial relaxation,
an observation previously attributed only to the acute administration
of estrogen.
The side effects of GnRHa treatment are similar to those experienced by
postmenopausal women. Estrogen deficiency is recognized to be a cause
of vasomotor symptoms and bone loss, but postmenopausal women are also
at increased risk of cardiovascular disease. This is
partly due to the development of a more atherogenic lipid
profile,9 but more recently, direct effects on
the cardiovascular system have been identified as being
more important contributors to the increase in
risk.10
Despite convincing evidence to show that the menopause increases the
risk of cardiovascular disease, few studies have been
undertaken on the effects of GnRHa on the
cardiovascular system. It remains unclear whether the
administration of a GnRHa has a detrimental effect on vascular
function, and if so, whether this effect is reversed with add-back HRT.
The aim of this study was to compare differences in vascular reactivity
between women using a GnRHa alone and women using a GnRHa in
combination with add-back therapy. This study design can be used as an
in vivo model of the effect of HRT on vascular reactivity in
postmenopausal women.
To determine the effect of add-back therapy on vascular function, blood
flow studies were performed before, during, and after the completion of
treatment with a GnRHa. This study was approved by the Ethics Committee
of the Chinese University of Hong Kong. Vascular reactivity was
examined by use of measurements of
endothelium-dependent and
endothelium-independent relaxation of the brachial
artery as described by Celermajer et al.11
Measurements of Vascular Response
Endothelium-dependent and -independent changes in
vascular reactivity were assessed by measurement of changes in the
diameter of the brachial artery. The right side was chosen for the
convenience of the operator, with a previous study of a similar nature
having established that there were no significant differences between
the right and left sides.12 All measurements were
made over the brachial artery, where a mark was made on the skin with a
marker pencil at each examination to minimize error related to movement
during the examinations. The artery was scanned in the longitudinal
plane, and the depth of focus was set at the center of the artery. To
provide more accurate measurements of changes in arterial
diameter than would have been possible with the calipers on the
ultrasound monitor, all of the examinations were recorded with scan
magnification onto s-VHS tapes, as shown in Figure 2
Endothelium-dependent relaxation was assessed by
measurement of the change in diameter of the artery occurring as a
result of reactive hyperemia. A resting measurement was taken,
and then a pneumatic cuff was inflated to a pressure of 200 mm Hg
for 4 minutes. The diameter of the artery was recorded again 45 to
60 seconds after cuff deflation. Fifteen minutes was then allowed for
recovery before testing for endothelium-independent
relaxation. A repeat baseline measurement of the diameter of the artery
was made before a 400-µg dose of sublingual glyceryl trinitrate spray
(GTN) was administered (Nitrolingual spray, Pohl-Boskamp GmbH). The
brachial artery diameter was then measured 3 to 4 minutes after the GTN
had been given.
Statistical Considerations
The sample size was calculated on the basis of a previous study by
Anderson et al13 that showed a 13.8% increase in
brachial artery diameter in normal subjects in response to reactive
hyperemia compared with a 7.2% increase in those with
endothelial dysfunction. With a minimum of 5 patients
in each arm of our study, such a sample size should be able to detect a
difference between 2 groups with
Table 1
Table 2
Table 3
Few studies have investigated the effects of GnRHa on
cardiovascular risk. Most of these have examined
changes in the lipid profile,1 18 19 20 but these
changes have been of small magnitude and did not appear to persist
after withdrawal of the treatment.
There is accumulating evidence to show that the direct effect of
estrogen on blood flow may play a far more important role than changes
in the lipid profile. Estradiol has been shown to have an acute effect
on vascular resistance, resulting in an increase in blood flow through
both endothelium-dependent (via nitric oxide) and
-independent (smooth muscle) mechanisms.10
Arterial relaxation through an
endothelium-dependent mechanism has been demonstrated
with the acute administration of estrogen, but long-term treatment is
thought to alter vascular function through other actions, like those of
a calcium antagonist, or by the inhibition of
atheroma formation.21 22
To the best of our knowledge, there has been only 1 study on the effect
of GnRHa administration on cardiac function in young
women.23 In this study, 15 women underwent
Doppler echocardiography during GnRHa
treatment, and significant reductions in peak flow velocity and cardiac
index were demonstrated. There was also a nonsignificant reduction in
flow velocity and a significant decrease in mean acceleration. It was
concluded that the hypoestrogenism associated with this treatment had a
direct effect on cardiovascular performance.
One other study examined changes in the resistance index of the uterine
arteries of women with uterine fibroids treated with a
GnRHa.24 After >4 months of this treatment,
there was a significant increase in vascular resistance, and this
increase correlated closely with the reduction in uterine size during
treatment. The only study in which the use of a GnRHa was found to have
no effect on blood flow was that reported by Penotti et
al.25 In that study, a 6-month course of
treatment was found to produce no significant changes in the
pulsatility index in the internal carotid and middle cerebral arteries,
and it was concluded that because the resistance of these arteries was
unaltered by treatment, they must be under extraestrogenic control.
Our study investigated whether a 6-month course of treatment was
associated with changes in vascular function in an
endothelium-dependent or -independent fashion. Of note,
over the duration of the study period, the resting diameter of the
brachial artery tended to change in both groups, as shown in Table 1
Within the group that received no add-back therapy (group 1), there was
a significant reduction in endothelium-dependent
arterial relaxation during treatment with the
GnRHa, but 3 months after discontinuation of treatment,
values returned to baseline. In those who received add-back therapy,
however, the inhibition of relaxation observed with the GnRHa alone was
removed, suggesting a positive effect of add-back therapy on
endothelium-dependent relaxation. In this group, values
also returned to baseline after the discontinuation of treatment.
Significant changes in endothelium-independent vascular
function were not found in this study, although
endothelium-independent mechanisms are thought to
account for most of the cardioprotective effect of estrogen in the
chronic situation. There were no significant differences in brachial
artery diameter within the groups, nor were there significant
differences between groups. These results suggest that the effects of
GnRHa and add-back therapy are dependent on the
endothelium and are presumably mediated via nitric
oxide in a chronic situation.
Although it might be expected that the progestogenic component of the
add-back therapy could interfere with the favorable effect of estrogen
on vascular function, this aspect of therapy was not investigated in
our study. Some studies in humans have found that the addition of a
progestogen to estrogen therapy attenuates the improvement in vascular
reactivity attributable to estrogen. This has been demonstrated in
studies using the progestogens norgesterel26 and
norethindrone.27 However, 1 report on the effect
of medroxyprogesterone acetate on the pulsatility
index suggested that this progestogen did not interfere with the
beneficial effect of estrogen.28 To have
investigated the contribution of the progestogen in our study, it would
have been necessary to compare standard add-back therapy (in which both
estrogen and a progestogen are used) with estrogen alone. In our study,
however, the aim was to examine the effect of standard add-back therapy
on vascular reactivity.
The results of our study are of clinical significance not only to women
using GnRHa but also for postmenopausal women using HRT. As far as
GnRHas are concerned, treatment for a 6-month period appears to
interfere with endothelium-dependent relaxation, but
the administration of hormonal add-back therapy negates this adverse
effect of treatment. As a clinical model for the effect of HRT on
vascular function, these results more importantly suggest that the same
advantages would be offered to postmenopausal women using this or other
similar treatments. These are important findings, as previous studies
have shown an endothelium-dependent effect of estrogen
only during acute rather than chronic administration. The results of
this study provide an additional explanation for the cardioprotective
effect of HRT in postmenopausal women.
Received February 11, 1998;
revision received May 26, 1998;
accepted June 16, 1998.
© 1998 American Heart Association, Inc.
Clinical Investigation and Reports
Prospective Randomized Study of the Effect of "Add-Back" Hormone Replacement on Vascular Function During Treatment With Gonadotropin-Releasing Hormone Agonists
Abstract
Top
Abstract
Introduction
Methods
Results
Discussion
References
Background—Gonadotropin-releasing
hormone agonists (GnRHas) are a group of drugs that with long-term use
induce a pseudomenopausal state in which estrogen production is
suppressed. They are commonly used in the treatment of sex
steroid–dependent conditions. "Add-back" hormone replacement
therapy is used to prevent menopause-like symptoms and bone loss during
GnRHa treatment, but it is also recognized that hypoestrogenism
adversely affects vascular function. The aim of this study was to
examine the effect of GnRHa and add-back therapy on vascular
reactivity. This model serves as a paradigm for the effect of hormone
replacement therapy in postmenopausal women.
Key Words: hormones • vasculature
Introduction
Top
Abstract
Introduction
Methods
Results
Discussion
References
The gonadotropin-releasing hormone agonists (GnRHas) are
analogues of GnRH that after prolonged exposure cause inhibition of
gonadotropin secretion and hypoestrogenism. This effect has been used
to advantage in the treatment of sex steroid–dependent conditions such
as endometriosis and uterine fibroids.1 2
However, a number of disadvantages are associated with the long-term
use of a GnRHa. These are related to hypoestrogenism and include bone
loss, the development of vasomotor symptoms, and memory
complaints.3 4 5 The problem of bone loss is
especially important, because this has not always been shown to be
reversible on withdrawal of treatment.6 To
overcome these problems, low-dose "add-back" hormone replacement
therapy (HRT) has been used during GnRHa treatment, and this has in
most cases been found to prevent the unwanted side effects of treatment
without interfering with its primary
action.7 8
Methods
Top
Abstract
Introduction
Methods
Results
Discussion
References
Patients
A prospective, randomized, controlled study was performed in the
Prince of Wales Hospital in Hong Kong between January 1996 and July
1997. Fifty women with a laparoscopic diagnosis of endometriosis that
had been made within 3 months of their entry into the study were
recruited. The decision regarding their need for treatment with a GnRHa
had been made by medical staff who were not involved in the study. All
subjects were Hong Kong Chinese women in the reproductive age
range. All had been shown to be ovulatory before the laparoscopy on the
basis of biphasic basal body temperature charts or luteal-phase
progesterone assays. The study period was of 9 months' duration. A
schematic diagram of the study design is shown in Figure 1
. Subjects were randomly allocated to 1
of 2 treatment groups. Randomization was performed with block
randomization and a random table, with 25 subjects being randomized to
each group. Subjects in group 1 received a GnRHa alone for 6 continuous
months. Subjects in group 2 were also given a GnRHa for 6 continuous
months, but in addition, they received add-back therapy during the
second 3 months of GnRHa treatment. The GnRHa was administered by
monthly injection of 3.75 mg leuprorelin acetate IM (Enantone SR,
Takeda Chemical Industries Ltd). The add-back was in the form of 2 mg/d
of estradiol and 1 mg/d of norethisterone acetate (Kliogest, Novo
Nordisk). The progestogenic component of these types of preparations is
necessary to protect the endometrium of the uterus against
estrogen-induced hyperplasia. This combination of estradiol and
norethisterone acetate has previously been shown to be an effective
method of providing add-back for women using
GnRHa,7 but the same combination is more commonly
prescribed as HRT for postmenopausal women. Compliance with add-back
therapy was assessed by direct questioning and by inspection of used
packages of the drug.
View larger version (11K):
[in a new window]
Figure 1. Schematic of study design showing time intervals
between each study and difference in treatment between groups.
The peripheral vascular response was studied with a
color duplex Doppler ultrasound (Aloka S-680 with a steered 7.5-MHz
peripheral vascular ultrasound probe (Aloka UST-5518-7.5).
All vascular response studies were performed by the same investigator,
who had no knowledge regarding the treatment of individual subjects. To
provide a stable environment in which to conduct these studies, all
subjects fasted for at least 2 hours before each examination. These
were performed in a quiet room with constant light and a room
temperature between 21°C and 22°C. Subjects rested in a supine
position for 15 minutes before measurements were made. , and studied retrospectively. A video
frame grabber was used to capture individual frames into digitized
images, each with a resolution of 768x640 pixels. A software digital
micrometer was designed to measure between fixed reference
points on these images. The number of pixels between a 10-mm vertical
gradation scale on a single captured image was determined and
subsequently used to transform pixel distance measurements into real
distances. The brachial artery diameter was assessed during each phase
of the experiment by determining the perpendicular distance (in
millimeters) between the inner and outer edges of the
arterial wall on each of the digitized images. The
precision of measurement was determined by taking 5 repeated
measurements in 5 subjects over a period of 10 minutes. ANOVA found the
between-measurement variance to be 0.02 mm, with confidence
limits of ±0.24 mm. These measurements also showed that repeated
ultrasound examinations did not affect the diameter of the artery.
View larger version (93K):
[in a new window]
Figure 2. Ultrasound measurement of brachial artery diameter
captured on videotape (left). Arrows indicate brachial artery.
Measurement is made on right panel, in which image has been processed
and captured on computer.
The results were analyzed with the Statistical Package
for Social Sciences. The Wilcoxon matched-pairs signed-rank
test was used to compare the means of changes in brachial artery
diameter within the study groups. The Mann-Whitney U test
was used for comparison between groups. Because many external factors
affect the resting measurement of the diameter of the artery,
statistical analysis between groups was performed by comparing
changes in the diameter of the artery rather than by comparing
measurements of the diameter at the resting stage and after
intervention. Nonparametric analysis was used to
overcome possible variance between the 2 groups. 
of 0.05 and power of 80%.
However, to provide greater statistical power and to allow for study
dropouts, 50 women were recruited.
Results
Top
Abstract
Introduction
Methods
Results
Discussion
References
The mean age of the subjects in group 1 was 34.2±5.8 years,
whereas in group 2, the mean age was 35.1±6.7 years
(P=0.70). During the study period, 9 patients defaulted from
treatment, 4 from group 1 and 5 from group 2. Two of these moved away
from Hong Kong, and 2 others wished to stop treatment early to attempt
to conceive. The remainder were lost to follow-up and could not be
contacted. The results of these subjects were excluded from the final
data analysis. All subjects who completed the study remained
amenorrheic during treatment except for 5 subjects who received
add-back therapy, who reported at least 1 episode of vaginal spotting.
The spotting did not result in dropout from the study or failure to
comply with treatment. compares the mean baseline
brachial artery diameters before, during, and after treatment between
the 2 groups. There were no significant differences in the baseline
diameters between the groups throughout the study. Within group 1,
there was a significant increase in the resting diameter after both 3
and 6 months of GnRHa administration (P<0.01 at both time
intervals), but the value 3 months after the completion of treatment
did not differ significantly from the pretreatment value
(P=0.25). In group 2, there were no significant changes in
baseline arterial diameter throughout the study period.
View this table:
[in a new window]
Table 1. Mean Baseline Brachial Artery Diameters Before,
During, and After Treatment compares the mean
endothelium-dependent changes in arterial
diameter between the 2 groups. The mean change in diameter after the
reactive hyperemia was consistently found to be
greatest 1 minute after the release of the tourniquet. There was no
significant difference between the means of the change in diameter
between the 2 groups after 3 months of GnRHa treatment, but after the
addition of the add-back therapy, the increase in diameter in the
artery was significantly greater in the group that received add-back
therapy. In group 2, there was a 14.6% increase in the diameter of the
artery in response to the release of the cuff, compared with an 8.6%
increase in group 1 (P<0.01). Three months after all
treatment was completed, the measurements did not differ significantly
from those taken before the study commenced. Within group 1, there was
a significant reduction in the mean
endothelium-dependent change in arterial
diameter during GnRHa treatment (P<0.01 at both 3 and 6
months), but after completion of treatment, the mean change did not
differ significantly from the value taken before the study commenced
(P=0.40). Within group 2, there was a significant reduction
in the mean endothelium-dependent change in diameter
after 3 months on the GnRHa alone (P<0.05), but with
add-back therapy, the change was no different from the value taken
before the commencement of treatment (P=0.26).
View this table:
[in a new window]
Table 2. Mean Endothelium-Dependent Changes in Arterial
Diameter shows the
endothelium-independent changes in brachial artery
diameter during the study period. There were no significant differences
in the mean endothelium-independent changes in
arterial diameter between the 2 groups. In addition, there
were also no significant differences in the mean
endothelium-independent change in arterial
diameter within each group.
View this table:
[in a new window]
Table 3. Mean Endothelium-Indepentent Changes in Brachial
Artery Diameter
Discussion
Top
Abstract
Introduction
Methods
Results
Discussion
References
Hypoestrogenism resulting from the menopause predisposes women to
an increased risk of osteoporosis and cardiovascular
disease.9 14 The prolonged use of a GnRHa induces
a reversible menopausal state, and women using GnRHas have been shown
to experience symptoms similar to those of postmenopausal women and
also to suffer bone loss. In a situation analogous to that of
postmenopausal women using HRT, the administration of add-back therapy
to women using a GnRHa has been shown to reduce symptoms of
hypoestrogenism and to protect against bone loss. This appears to occur
without stimulating the estrogen-dependent condition that is being
treated with the GnRHa. Several studies have investigated whether
pelvic pain due to endometriosis is exacerbated during add-back
therapy,7 15 16 17 1 of which used the same regimen
of add-back as was prescribed in our study.7 None
of these demonstrated a difference in pain scoring during add-back
therapy, and for this reason, a pain score was not used in our
study. 
.
Many external factors can affect the resting diameter of the artery,
and we believe that these may have contributed to the observed
differences. This emphasized the importance of studying changes in
diameter of the artery rather than comparing measurements of the
diameter at the resting stage and after intervention.
References
Top
Abstract
Introduction
Methods
Results
Discussion
References
This article has been cited by other articles:
 |
|
 |
|
  G. Mercuro, F. Saiu, M. Deidda, S. Mercuro, C. Vitale, and G. M. C. Rosano Effect of Hormone Therapy on Exercise Capacity in Early Postmenopausal Women Obstet. Gynecol., October 1, 2007; 110(4): 780 - 787. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Collins, M. Flather, B. Lees, R. Mister, A. J. Proudler, J. C. Stevenson, and on behalf of the WHISP (Women's Hormone Interventi Randomized trial of effects of continuous combined HRT on markers of lipids and coagulation in women with acute coronary syndromes: WHISP Pilot Study Eur. Heart J., September 1, 2006; 27(17): 2046 - 2053. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Jokela, P. Dastidar, R. Rontu, A. Salomaki, K. Teisala, T. Lehtimaki, and R. Punnonen Effects of Long-Term Estrogen Replacement Therapy Versus Combined Hormone Replacement Therapy on Nitric Oxide-Dependent Vasomotor Function J. Clin. Endocrinol. Metab., September 1, 2003; 88(9): 4348 - 4354. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. B. Sorensen, P. Collins, P. J.L. Ong, C. M. Webb, C. S. Hayward, E. A. Asbury, P. D. Gatehouse, A. G. Elkington, G. Z. Yang, A. Kubba, et al. Long-Term Use of Contraceptive Depot Medroxyprogesterone Acetate in Young Women Impairs Arterial Endothelial Function Assessed by Cardiovascular Magnetic Resonance Circulation, September 24, 2002; 106(13): 1646 - 1651. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. S. Surrey and M. D. Hornstein Prolonged GnRH Agonist and Add-Back Therapy for Symptomatic Endometriosis: Long-term Follow-up Obstet. Gynecol., May 1, 2002; 99(5): 709 - 719. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. J. Mather, E. G. Norman, J. C. Prior, and T. G. Elliott Preserved Forearm Endothelial Responses with Acute Exposure to Progesterone: A Randomized Cross-Over Trial of 17-{beta} Estradiol, Progesterone, and 17-{beta} Estradiol with Progesterone in Healthy Menopausal Women J. Clin. Endocrinol. Metab., December 1, 2000; 85(12): 4644 - 4649. [Abstract] [Full Text]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||