Clin. Cardiol. 24, 271-275 (2001)
Reviews
The Cardiovascular Response
to
Sexual Activity:
Do
We
Know
Enough?
RODNEY
H.
FALK,
M.D.
Boston Medical Center, Boston University School of Medicine, Boston, Massachusetts,
USA
Summary:
Interest
in
comprehensive cardiac rehabilitation
over the past 25 years spawned a series of small investiga-
tions concerning the heart rate, blood pressure, and ischemic
response to sexual intercourse. This information was ade-
quate for advising patients about return to sexual activity af-
ter a myocardial infarction or cardiac surgery. However, the
introduction of medications for erectile dysfunction enabled
impotent cardiac patients to engage
in
sexual activity and has
highlighted the need for more detailed information concern-
ing cardiovascular physiology during coitus. Review of the
medical literature indicates a remarkable paucity of such data
despite dramatic advances
in
most other aspects of cardiovas-
cular physiology and pathophysiology. This brief paper gives
an overview of the current knowledge of the cardiovascular
response to sexual activity and,
within
the framework of ad-
vances
in
cardiology, highlights areas where it appears im-
portant to
fill
in
the knowledge gap.
Key
words:
sildenafil, hemodynamics, sexual activity
Introduction
The
last
quarter of the century has seen remarkable changes
in
all fields of medicine as far apart
as
cardiology, endocrinol-
ogy, and urology. Among the
many
new aspects
in
the field of
cardiology is an appreciation of the interaction of the auto-
nomic nervous system with the heart, and the realization that
blunted cardiac autonomic function may,
in
diseased hearts,
be
a marker of electrical instability. Advances
in
reproductive
Address for reprints:
Rodney
H.
Falk, M.D.
Boston Medical Center
Section
of
Cardiology
88 East Newton Street
Boston. MA
02
1
18.
USA
Received: January 10.2000
Accepted: February
2,
2000
physiology have vastly improved the treatment of infertility,
and concomitant with this
ha..
come a greater understanding of
male and female human sexuality. The most recent addition to
the sexual revolution has
been
the introduction of oral medica-
tion that is highly effective for the treatment of male erectile
dysfunction.'
One area of investigation which appears to have lagged
be-
hind almost every other aspect of urology and cardiology. yet
which bridges the two disciplines, is an understanding of the
cardiovascular physiologic response to sexual activity.
Be-
cause of the personal and sensitive nature of human sexual ac-
tivity, the small studies of cardiovascular function that have
been performed have been limited to such measurements
as
heart rate, blood pressure, and, occasionally, to electrocardio-
graphic abnormalities documented by Holter
Even those studies published
in
the
1990s
limit themselves to
measurements and techniques available a quarter of a century
ago.4.
7,
*
Until recently, there was little reason, other
than
an
aca-
demic one, to delve into more detail. However, with the intro-
duction of sildenafil as the first oral medication for the treat-
ment of erectile dysfunction, the importance of knowledge
in
this area has become apparent. Although generally safe and
well tolerated, sildenafil may cause profound and dangerous
hypotension when used in conjunction with nitrates-agents
that are commonly prescribed for patients with coronary ar-
tery disease.
As
a result of concerns about sildenafil use
in
pa-
tients with cardiac disease, the American College of Cardiol-
ogy
and the American Heart Association recently produced
an
expert consensus document that reviews the use of silde-
nafil
in
light of current knowledge of sexual activity.20
A
strik-
ing aspect of
this
carefully produced and thoughtful docu-
ment is the paucity of detailed studies that have investigated
the cardiovascular response to sexual activity. The following
overview briefly reviews the current knowledge about this re-
sponse and highlight gaps
in
knowledge that would benefit
from intensive investigation.
Sexual
Activity
and
Cardiovascular Respon-
What
Do
We
Know?
Table
I
summarizes
the main published studies of cardiovas-
cular parameters recorded during sexual activity. These studies
can
be
divided into
two
groups; those performed
in
normal
sub-
272
Clin.
Cardiol.
Vol.
24, April 2001
TABLE
I
Summary
of
main studies
of
the cardiovascular response to sexual activity
First author Subjects
HR
at orgasm Systolic BP at
(Ref.)
(age)
(range) orgasm (range) ECGiHolter
Comments
Normal subjects
Nemec 10male
1976
(5)
(40-61)
Larson 9 male
1980(21)
(4041)
Bohlen
10
male
1984(3) (2%3)
2 intercourse
positions
2 non-
intercourse
stimulation
1
l4k 14 163k11 Occasional No difference between man
or
woman
ect0PY on bottom
123
146
No arrhythmia Mean
HR
and
BP identical at orgasm
as
at
(88-155)
(1
30-1 68) top of 22
stairs
127k23 NIA Not done
MVCh
measured. Double product
(intercourse)
102k 14
(selflwife
stimulation)
maximum
with
man
on top
Subjects with cardiac disease
Johnston
1979(13)
Larson
1980
(21
)
Jackson
1980(1
I)
Stein
1977(18)
Hellerstein
1970(10)
Drory
I995
(7)
MW
1980 (26)
Men post-MI
(n=9)or
Pst-CABG
(n=
15)
(37-66)
(39-66)
8
men “CAD”
35
with CAD
(5
women)
(36-70)
16 men
post-MI
(40-54)
14 men
mean age 48
post
MI
(36-66)
Most post
MI
No cardiac
medications
88
men
3 women
(mean age
35)
8
men
Untreated
hypertension
I10
(
100-1
50)
1
I5
122rt7
127 (120-130)
before exercise
training
120
(
1
15-1
22)
after training
1
I8
(90-140)
1
I8
(80-185)
124 (men)
139 (women)
NIA
144
(
122-1 70)
NIA
NIA
NIA
NIA
14/76 (women)
155187 (men)
precoital to 2 161
127 (women) and
2371138 (men)
1
subject had
increased
ventricular
KtOPY
SVT
in
one
patient
No
4/14 with
ST
depression
2 with PVCS
Complex PVCs
in
13%.31%
with ischemia
(symptomatic
in
7%)
1
patient had
peak
heart rate of 92 with
wife and
150
with girlfriend
Stair
climbing (22 steps) associated with
higherBP(mean 164;range 136-180)
but similar
HR
to peak
sexual
values
Angina with intercourse
in
65% patients
Abolished by
beta
blockade which was
associated with reduction in peak
HR
to
82
f
6 bpm
E’IT
performed to same
HR
as
peak sexual
rate.
Concluded that intercourse requires
only
“modest oxygen costs”
Arrhythmia not predicted by
ETT
but
ischemia during intercourse only
occurred when
also
present on E’IT
BP recorded during a study of
intra-arterial
ambulatory blood pressure measurement
Abbreviations:
BP= blood pressure, CABG =coronary
artery
bypass
grafting,
E’IT
=
exercise tolerance testing,
HR
=
heart
rate,
MI
=
myocardial
infarction,
NIA
=
not available, PVC
=
premature ventricular contraction,
SVT
=
supraventricular tachycardia.
R.H.
Falk: The heart and sex
213
jects and those
in
patients with coronary artery disease. It can be
seen that the peak heart rate achieved during sexual intercourse
is approximately 125 beatdmin with a
peak
systolic blood pres-
sure of 150-160 mmHg. Based on these data
it
has generally
been
estimated that the energy expended during sexual activity
is equivalent to walking up one or two flights of
stairs.Io-
21
It is generally recommended that a patient may return to
normal sexual activity almost immediately following hospital
discharge for myocardial infarction provided that
he
has no in-
ducible ischemia on predischarge exercise treadmill testing.
Unfortunately, the simplicity of such advice is not matched by
the potential complexity surrounding sexual activity
in
the car-
diac patient. Thirty years ago, physicians rarely counseled
their patients after a myocardial infarction on resumption of
sexual activity, and studies demonstrated that many patients
never resumed such activity at its prior frequency,
if
at
Although today’s cardiologists have the data listed above on
which to rely
in
order to recommend the early resumption of
sexual relations, there are still reasons why patients may not
do
so.
The multiplicity of drugs prescribed
to
modern-day pa-
tients often includes medications that may impair sexual func-
tion. Postinfarction depression and associated impotence
are
common,23 and routine counseling on return to sexual activity
is almost certainly lacking
in
many cases. Even when sexual
activity is resumed,
it
often continues at a lesser frequency than
before the myocardial infar~tion.~~
Although return to sexual activity after a myocardial
in-
farction is generally safe,
it
is important to recognize that all
the studies of the cardiovascular response
to
sexual activity
(including assessment of the risk of triggering a myocardial
infar~tion~~) were performed
in
subjects able to perform sex-
ually, unaided by pharmacologic therapy. We cannot accu-
rately extrapolate from these small studies the risks of drug-
facilitated intercourse
in
previously impotent patients. Since a
major cause of erectile dysfunction is vascular disease, not
only the patient post infarction but also many other previous-
ly
impotent patients may have coronary artery disease, either
symptomatic or asymptomatic. Caution is also warranted
in
the patient
with
poorly controlled hypertension. Indeed, the
very sparse data on sexual activity
in
patients with hyperten-
sion suggest that peak systolic blood pressure may reach
more than 225 mmHg.26
With the use of sildenafil there is a risk that some patients
who previously would have been physically unable
to
have
sexual intercourse may now
be
exposed to sexually induced
myocardial ischemia.
In
the expert consensus document, sev-
eral recommendations were given for the cardiac patient who
wishes to take sildenafil.20 Apart from the obvious contraindi-
cations in patients requiring nitrate therapy, those patients who
are taking a combination of antihypertensive medications
were considered to be at high risk of sildenafil-induced hy-
poten~ion.~’.
28
Exercise treadmill testing, in order to uncover
stress-induced ischemia, was suggested
in
those patients with
suspected or known coronary artery disease. The authors
pointed
out that the ability to achieve more than
5
METS
with-
out myocardial ischemia during
an
exercise tolerance test
made the risk of coitus-induced ischemia unlikely. However,
they also stressed that
firm
data are lacking and that the physi-
cal and emotional stress of sexual intercourse can be excessive
in some people, particularly
in
those who have not performed
this activity
in
some time or are not in good condition.
Why Should Sexual
Activity
Provoke
Myocardial
Ischemia-Is
It
Simply the Workload?
Sexual activity clearly has both a physical and emotional
component, and the various components of the sexual re-
sponse are characterized by
a
complex interaction of the
sympathetic and parasympathetic arms of the autonomic ner-
vous system. The parasympathetic nervous system is respon-
sible for the production and maintenance of erection, where-
as the sympathetic nervous system, by virtue of its
vasoconstrictor effect on the smooth muscle
in
the erectile
tissue arteries, is responsible for maintaining flaccidity and
producing detumescence after orgasm. It is intriguing that pe-
nile detumescence after orgasm is mediated by noradrenergi-
cally induced tonic vasoconstriction, yet preorgasmic tachy-
cardia is also sympathetically mediated and occurs at a time
when erection is maintained. This demonstrates the fine bal-
ance between the neural and biochemical components of nor-
mal sexual physiology.
Among the advances in cardiovascular pathophysiology
in
the
last
decade is arecognition that endothelial dysfunction
in
patients with coronary artery disease is associated
with
para-
doxical coronary artery vasoconstriction during mental and
physical e~ertion.~~-~~
This
phenomenon is also sympatheti-
cally mediated and can be entirely blocked by the intracoro-
nary
administration of phentola~nine.~~ One might therefore
postulate that during sexual intercourse, when sympathetic
tone is high, patients with coronary artery disease (and hence
endothelial dysfunction) may be prone to coronary artery
vasoconstriction.
In
one study,
31%
of patients with docu-
mented coronary artery disease had electrocardiographic evi-
dence of myocardial ischemia (painless or painful) during
sexual intercour~e.~ Although this was a highly selected pop-
ulation, it demonstrates that, despite relatively niodest meta-
bolic demands, significant ischemia may occur.
Since psychological factors are clearly very potent during
sexual activity,
it
is
easy to understand why tachycardia or is-
chemia in some patients may seem excessive for the amount of
physical work. While it is likely that myocardial ischemia dur-
ing sexual intercourse is provoked by a combination of neural-
ly mediated and physical factors, at present this remains
un-
proven.
In
the era of oral medications for erectile dysfunction,
this
is a direction of research that is clearly important.
What
More
Do
We
Need
to
Know
about the
Cardiovascular
Response
to
Sexual
Activity?
Several
aspects
of cardiovascular function are fertile for in-
vestigation. Among them are the effects of sexual intercourse
on ventricular electrical stability, on cardiac hemodynamics,
274
Clin. Cardiol.
Vol.
24,
April
2001
and on coronary artery tone. In patients with left ventricular
dysfunction,
it
is conceivable that relatively unopposed sym-
pathetic tone may lead not only to myocardial ischemia but
also
to an increased propensity to ventricular arrhythmias.
Studies utilizing Holter monitoring have demonstrated that
some patients do develop ventricular arrhythmias during sex-
ual intercourse,8 but their clinical significance is unknown.
Noninvasive tests of ventricular stability more sensitive
than Holter monitoring have recently
been
developed. Among
the newer cardiac tests is the measurement of T-wave alter-
nan~.35-~~ T-wave alternans,
a
microvolt phenomenon, is heart
rate related and, when present, is a marker
of
an increased
propensity to sudden cardiac death. T-wave alternans during
exercise testing occurs in a significant proportion of patients
with coronary artery disease and left ventricular dysfunc-
tion.” Concomitant with the development of newer cardiac
studies has been the introduction
of
laboratories dedicated to
the study of sexual function and dysfunction.
In
these labora-
tories, sexual arousal can be induced by the combined use of
erotic visual stimuli (delivered individually to the patient
through special spectacles) and genital stimulation. At the
same time a variety of physiologic events can be monitored.
The occurrence of T-wave altemans could easily be recorded
in
the laboratory during sexual activity and could be correlat-
ed
with
similar electrical abnormalities detected during stan-
dard exercise testing.
The portability
of
the equipment used to provoke sexual
arousal would also permit more invasive cardiac studies. It
should be possible
to
determine cardiac output utilizing
Swan-Ganz catheterization and even to perform left-sided
cardiac catheterization and coronary angiography. Physical
and mental stress testing has been performed successfully
during cardiac catheterization, and quantitative coronary an-
giography has demonstrated that diseased coronary arteries
show
a
paradoxical vasoconstrictor response
to
mental
stress
and physical It is likely that the same finding
may occur
with
sexual activity, but
it
is
also
possible that the
autonomic influences on the heart may be different and that
patients with coronary disease may have more (or less) para-
doxical vasoconstriction during sex than during mental
or
physical exertion. Clearly, it is important to know the likely ef-
fect that sexual intercourse has on coronary artery tone when
advising
a
patient
with
severe coronary artery disease about
the use
of
pharmacologic therapy for erectile dysfunction.
A
particularly intriguing question is the
role
that drugs pre-
scribed for erectile dysfunction have on coronary tone.
Sildenafil was originally developed as an antianginal agent
and has potent vasodilator properties. Oral phentolamine is
now being investigated
as
a therapy for impotence. In prelimi-
nary
clinical trials, this drug has been shown to be effective
for
erectile dysfun~tion~~ and,
as
noted,
it
is effective
in
preventing
stress-induced coronary vasoconstriction when administered
into the coronary arteries. Whether
or
not the blood level
achieved after oral phentolamine would be sufficient to pre-
vent paradoxical vasoconstriction is unknown but,
if
sufficient,
such an agent might reduce the likelihood of ischemia during
sexual activity.
The twenty-first century will continue to
see
advances
in
cardiology, urology, and every other discipline in medicine.
With the aging of America and the desire to continue
a
healthy
lifestyle into
an
increasingly older age,
an
increasing number
of older patients will
be
requesting help with erectile dysfunc-
tion-a condition formerly believed to
be
an
inevitable result
of
aging. As physicians we have a duty to respond to these re-
quests, but we are also duty bound to respond
in
an educated
manner.
In
order to do
so,
we must acknowledge that most of
the framework of knowledge
in
this
field was gathered about a
quarter of a century ago.
As
we enter the new millennium, we
must insist that
our
understanding of cardiovascular sexual
physiology and pathophysiology catches up with the remark-
able advances in other aspects
of
cardiovascular function that
have
been
made
in
the last
25
years.
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