Indian J Med Res 130, December 2009, pp 681-688 Cardiovascular effects of sexual activity Xiaojun Chen, Qingying Zhang* & Xuerui Tan Department of Cardiology, The First Affiliated Hospital of Shantou University Medical College & *Department of Preventive Medicine, Shantou University Medical College, Shantou, Guangdong, China Received June 11, 2008 Sexuality is a major way of intimacy in human being and it is very important in gender relationship,
contributing to over all health. However, since association between sexual activity and sudden death
determined by forensic autopsies related to cardiac or cerebral causes has been reported, some people with
heart disease often abstain from sexual activity that could affect the quality of life. It is therefore important
to learn the physical demand of sexual activity and the risk it may trigger. For decades, the cardiologists
have conducted observational studies and clinical trials on healthy volunteers or patients. The most
common indices responding to cardiovascular risks of sexuality were variances of blood pressure (BP) and
heart rate (HR), monitored by ambulatory blood pressure and dynamic electrocardiogram recording. BP
and HR increase during the coitus just briefly and quickly recover to baseline level. Peak coital BP occurred
at onset of plateau phase and quickly decreased, instead of emerged at orgasm as most people supposed.
The metabolic equivalent of energy expenditure during the orgasm was relatively modest when compared
with other physical exertion such as cycling. Epidemiological studies have suggested that sexual activity
has favorable effect on health in the long term. This review summarizes and discusses the advances in the
researches dealing with cardiovascular effects of sexual activity to better inform the cardiac patients.
Key words Cardiovascular system - risk - sexual activity - sudden death
clinicians to identify strategies for prevention and offer Effect of sexual activity on health has long been valuable suggestion. This article reviews literature on a debated topic with focus on cardiovascular system. various epidemiological, observational, randomized trials and self-reported surveys during the last five Patients with heart disease often have fear of coital sudden death or triggering a cardiac event, which actually lower their quality of life. Physiological and Adverse effect of sexuality on cardiovascular
clinical aspects of sexual function have been extensively studied in patients who have angina, have experienced Coital death: Coital death has often been attributed to a myocardial infarction1-5, have undergone coronary various causes such as cardiac disease or intracerebral artery bypass graft surgery6 or heart transplant7 and haemorrhage. Like any form of physical exercise or those with chronic heart failure8. A better understanding anger, sexual activity increases heart rate (HR) and of cardiovascular effects of sexual activity may help blood pressure (BP), and it has been identified as a INDIAN J MED RES, DECEMBER 2009 Table I. Mortality related to sexual activity
Superscript numerals represent Ref. no.
trigger for myocardial infarction (MI)9, or even sudden risk attributed to coitus was found to be far less than death, especially for those with heart disease10. To fill that associated with anger and unaccustomed physical up the gap of lack of data and insufficient information, exercise, and during the 2 to 4 h after awakening four major studies were initiated to determine the risk associated with diurnal variation15. of sudden death based on autopsy findings (Table I)11-14.
Mechanism of cardiovascular risks related to sexual In the death examination archived in Berlin11 from activity: The most likely mechanism for the triggering 1956 to 1976, 30 (1.7%) of 1722 forensic autopsies effect of heavy physical exertion and sexual activity were described as unexpected deaths occurring during is increased sympathetic activity, particularly in sexual activity. Only 2 cases were women. Twenty non trained individuals. Increased HR, BP, platelet three cases of fatal events were preceded by extra- aggregability and increased coronary vasomotor tone marital intercourse. Of the 30 deaths, five took place may be involved as potential underlying mechanisms16, before, 9 during and 16 after the coitus. These findings by which a potential transient exposure may trigger MI were consistent with data from another large-scale related to the existence of vulnerable atherosclerotic German study, which was a medico-legal post-mortem plaques. Heavy physical exertion, including sexual study performed in Frankfurt over a 33-yr period, activity, could induce a cascade of events resulting MI about 31691 forensic autopsies revealed 68 (0.22%) through their effect on the sympathetic nervous system. natural deaths occurring during sexual activity12. Most Other acute exposures may trigger cardiovascular of the deaths occurred in men (92.6%). The majority disease through different mechanisms17,18.
of the deaths occurred during extra-marital intercourse (n=39). Only 19 of the fatal events occurred in the Exercise tolerance of sexual activity: In comparing victim's home (n=16) or the home of long time partner sexual activity with other forms of activity, the (n=3). The pathological findings of this autopsy study most commonly used clinical measure is the (1972-2004) revealed that sexual activity with an extra- metabolic equivalent of energy expenditure (MET). marital partner could pose a risk of health for those with For comparison, walking at 2 mph on level ground cardiac disease. Among the causes of death, coronary would equate to 2 METs; walking at 3 mph, 3 METs. artery disease (CAD) without signs of myocardial Preorgasm of sexual activity averages 2-3 METs; infarction accounted for one third cases, followed by orgasm during sexual activity 3-4 METs. Compared myocardial reinfarction and MI. to higher-intensity physical exertion, such as cycling at 10 mph (6-7 METs) or walking on the treadmill In Asia, the study results of Ueno13 in Japan and (13 METs), the exertion of sexual activity is relatively Sanghan Lee and colleagues in Korean14 were consistent modest19. Level of sexual function appears to have a with the western data that men were the major victims significant link with the 6 min walk test20. Hellerstein of sudden death in the context of extra-marital relations & Friedman first suggested that the equivalent oxygen and their underlying cardiovascular disease led to death cost of the average maximum HR during sexual predominantly. It is presumed that the secret immoral activity was less than that of climbing two flights of sexuality in unfamiliar setting or alcohol or heavy food steps or walking briskly2. Larson et al21 compared may significantly increase the BP and HR, resulting the HR and BP responses to both sexual activity in sudden death or cardiovascular events14; however and stair-climbing and found no difference in HR the chances of it are very low. Indeed, the increase in response in coronary artery disease (CAD) patients CHEN et al: CARDIOVASCULAR EFFECTS OF SEXUAL ACTIVITY between these two activities. However, the average Sexual activity as a promoter of health: Sexuality is systolic blood pressure was significantly higher in an essential aspect of normal human function, well- stair climbing compared to that of sexual intercourse. being and quality of life. In fact, several longitudinal While Bohlen et al22 suggested that the challenge of studies of varying duration have demonstrated an two flights of stairs might not apply to all patients22, inverse relationship between sexual activity and risk Drory10 regarded that equating energy expenditure for death, although their trial designs did not enable during coitus with ‘climbing two flights of stairs' was determination of the direction of causality. The Duke a potentially misleading oversimplification.
First Longitudinal Study of Aging32, a 25 yr trial involving 270 men and women aged 60-94 yr at study Attitude towards sexual activity and its effect
outset, found that the frequency of sexual intercourse Impaired sexual activity: Although coital death for was a significant predictor of longevity in men. cardiac patients is rare and its cardiovascular risk is Conversely, a Swedish study involving33 128 married low, it still exists, which prevents many people from men aged 70 yr followed for 5 yr showed that early sexual activity for fear that it may cause sudden death cessation of sexual intercourse was associated with an or reinfarction, dyspnoea, anxiety, angina pectoris, increased risk for death as compared with continuing exhaustion, changes in sexual desire, depression, sexual relation33. From a different perspective34, the loss of libido, impotence, partner's anxiety or Catholic priests and nuns, who were celibates, offered concern, and feeling of guilt23. Fear of a cardiac another epidemiological design. A retrospective cohort event during sexual intercourse can interfere with analysis involving 10026 priests in the United States patients' ability to perform and enjoy sexuality24. revealed the overall standardized mortality ratio (SMR) For example, unstable angina and non-ST evaluation of 103 and the SMR for cancer of the prostate was 8134. MI patients have a negative impact on frequency of, and satisfaction with, sexual activity, and lead to A study of nuns found opposite findings, with lower sexual dysfunction within a large number of female overall mortality than in the general population35. patients25. Those with CAD have a more than two- The 2,573 Catholic sisters had high rates of mortality fold risk of sexual dysfunctions compared with age- from cancers of the breast and reproductive organs, matched healthy persons26. It is well known that suggesting an effect of nulliparity manifested in older sexual activity is reduced in patients with coronary disease. In men with chronic heart failure, sexual Counselling on sexual activity for patients: It is activity is depressed27,28. important for the clinicians to know how to counsel Many men with established cardiovascular disease patients on sexual activity and the effects of some have erectile dysfunction (ED), the inability to achieve pharmacologic therapies. The most important and maintain an erection sufficient to permit satisfactory information for counselling is the absolute difference in sexual intercourse29. Endothelial dysfunction is risk the activity produces36. For instance, Framingham thought to be the common denominator of ED. Heart Study research indicates that the risk of a 50 yr Defined as a reduced vasodilation or even paradoxic old non smoking, non diabetic man to experience an vasoconstriction in response to endothelium-dependent MI is 1 per cent per year, or 1 chance in 1 million per vasodilatory stimuli, endothelial dysfunction in many hour37,38, because the relative risk (RR) of MI is doubled circumstances precedes morphological changes of the by sexual activity, such an individual will only increase vessel wall or the formation of atherosclerotic plaques30. his hourly risk to 2 in 1 million, and only for a 2 h With injury to the endothelium, the nitric oxide-cyclic guanosine monophosphate axis is impaired, interfering Considering the potential risk of cardiovascular with smooth muscle relaxation and vasodilatation as disease associated with sexual activity, the First a response to neural stimulation31. Due to the close Princeton Consensus (Princeton I) in 1999 developed association of cardiovascular disease and ED, patients guideline for assessment and management of patients with ED should be evaluated as to whether they may with varying degrees of cardiac risk39. These guidelines suffer from cardiovascular risk factors including were updated in 2004 (Princeton II) based on new data hypertension, cardiovascular disease or silent concerning the link between ED and cardiovascular myocardial ischaemia27. Increasing awareness of this disease and the new treatments availability40. Patients association should encourage men to discuss their ED can therefore be risk stratified about safety returning with medical practitioners.
to or continuing sexual activity. The asymptomatic INDIAN J MED RES, DECEMBER 2009 patients with fewer than three risk factors for CAD, to evaluate45 the metabolic expenditure in response to stable angina, recent uncomplicated MI, mild valvular sexual activity. Recorded BP and HR values in many heart disease, mild congestive heart failure (CHF) studies done before 1970s were much higher, almost - New York Heart Association class II41, controlled near that of maximum exercise, as those were taken hypertension, or post successful revascularization are in "unnatural" laboratory settings. A small study in considered low risk. Intermediate risk patients would 1956 reported that the peak HR was approximately include those with more than three risk factors for CAD, 125 bmp in coitus46. With the availability of portable recent MI, moderate CHF, peripheral vascular disease, ambulatory BP equipment in 1970s, the results came etc. High risk patients would be those with unstable up quite different from before. The HR obtained by angina, poorly controlled hypertension, severe CHF dynamic monitoring device and the BP measured by (New York Heart Association class III/IV), MI within non-simutaneous monitoring were remarkably lower 2 wk, significant arrhythmias, severe cardiomyopathies, than the previous reports. There were not more than 100 and moderate to severe valvular disease. Sexual activity subjects in each study, either healthy or with cardiac remains safe for a large majority of patients. The low disease from young to middle age (Table II). The risk category includes patients for whom sexual activity does not represent a significant cardiac risk. High risk researches focused on variances of cardiac responses patients should be referred for cardiologic assessment to sexual activity in different positions or different and treatment. Sexual activity should be deferred until phases. In general, for most individuals, it appears that a patient's cardiac condition has been stabilized by sexual activity is similar to mild to moderate intensity treatment or a decision has been made by a cardiologist exercise. This was true for individuals with or without that sexual activity may be safely resumed42,43. coronary disease. Besides safety and drug interaction data for three The peak HR during intercourse was no significantly phosphodiesterase type 5 (PDE5) inhibitors (sildenafil, higher in relation to the daily life HR for all patients47. tadalafil, vardenafil) suggested, lifestyle modification A study by Hellstein & Friedam showed the mean max is also important factor as obesity and sedentary HR in orgasm at 117.4 bpm with the equivalent BP at lifestyle have been shown as risk factors for ED in a 162/89 mmHg2. The ECG changes of the monitored number of cross-sectional and longitudinal studies44. subjects showed that the cardiovascular responses (ST- Intervening on cardiovascular and lifestyle factors may T segment depression, or ectopic beats and symptoms, have broader benefits beyond restoration of erectile or both) during coitus and occupational activities were comparable in frequency and severity2. The main Cardiovascular effect of sexual activity
findings of this study48 were: (i) one third of the patients had ischaemia, mostly silent, during intercourse; Laboratory research : BP and HR are the most direct (ii) all patients with ischaemia at intercourse also and common variance of cardiovascular indices, used had ischaemia during exercise; (iii) patients without Table II. Duration research of sexual activity
Findings during sexual activity Peak HR (beats/min) Arteriosclerotic disease 163 (MOT), 161 (MOB) 237/133 (M), 216/127 (F) Stable coronary disease MOT, man on top position; MOB, man on bottom position; M, male; F, female; HR, heart rat; SBP, systolic blood pressure; MI, myocardial infarction; CAD, coronary artery disease Superscript numerals represent Ref. no.
CHEN et al: CARDIOVASCULAR EFFECTS OF SEXUAL ACTIVITY ischaemia at exeraeise did not have ischaemia during Table III. Epidemiological research of sexual activity
sexual activity; and (iv) ECG findings showed that a Interviewees Methods greater number of patients had ischaemia during stress test compared with sexual activity. The mean peak HR 1979 57 The Caerphilly 914 men* at exercise was in fact higher than during intercourse. 1979 58 The Caerphilly 918 men* Another study49 demonstrated mean peak coital HR at 127 bpm before a 16 wk bicycle ergometer-training, Case-crossover analysis 12 to 15 wk following their first MI, and 120 bpm Case-crossover analysis after training programme during coitus. All 16 trained patients showed a significant decline in the measured Case-crossover analysis peak coital HR. It shows clearly the relationship of *Subjects are all male improved fitness consequent to exercise training and Superscript numerals represent Ref. no.
the reduction in peak HR achieved during sexual MIOS, Myocardial Infarction Onset Study; SHEEP, Stockholm Heart Epidemiology Programme In contrast to patients with heart disease, some The Caerphilly study57 was the first one to examine cardiologists targeted healthy people as their research the relation between frequency of sexual intercourse subjects. Sub-sample studies22,50 in healthy men, using and risk of ischaemic stroke and coronary heart disease ambulatory electrocardiogram during coitus in different (CHD), in Caerphilly, a former mining town in South position (man-on-top and man-on-bottom position) and Wales from 1979-1983. Of the 914 men studied, 197 different types (self-stimulation, partner stimulation) (21.5%) reported sexual intercourse less often than of sexual activity respectively, also demonstrated the once a month, 231 (25.3%) reported twice or more a moderate HR and BP, no superior to the maximum rate week, and the remaining 486 (53.2%) men fell into the observed during the day. The results were similar to that intermediate category. Frequency of sexual intercourse achieved in the cardiac patients. The reccent all healthy was not associated with all first ischaemic stroke events. subjects research conducted by Tan and colleagues53 on Longer follow up to 20 yr showed the risk decrease to 49 normal couples with 24 h Holter ECG and blood 1.69 (95% CI 0.90 to 3.20), contrasting low frequency examination, added the female data that the previous of sexual intercourse with the highest group. Odds of researches did not provide. Peak coital HR was found stroke among men suffering fatal strokes were lower in to occurr at the onset of orgasm phase in both sexes; those reporting intermediate and low levels of sexual peak BP occurred at onset of plateau phase instead intercourse. It is curious that at 10 yr of follow up, fatal of orgasm phase. Besides HR, BP, double product CHD events were more than twice as common in those recorded, they also observed the changes of plasma reporting an intermediate or low frequency of sexual endothelin (ET), thromboxane B (TXB ) and 6-keto- intercourse (intermediate frequency age adjusted OR - prostaglandin F1α(6-K-PGF1α) after sexual activity in 2.07, 95% CI 0.89 to 4.80 and low frequency- 2.80, 95% healthy adults and found no marked graded changes CI 1.12 to 6.96), showing a stronger effect than after 20 yr follow up. It was interesting to note that stroke 55,56. It is presumed that as a physiological was more common in those men who did not respond activity, sexuality should have perfect self-regulation to the question on sexual activity. Perhaps shared the mechanism that its physical demand is in the range of same group of subjects Ebrahim et al58 interviewed 918 daily activity, posing no cardiovascular risk. This is people, to assess the relation between frequencies of the first clinical research on sexual activity in China, orgasm and mortality. Over 10 yr of follow up 150 of representing data from Asian. HR and BP recorded the respondents died: 67 from CHD and 83 from other during the intercourse were either lower than the causes. They found that mortality risk was 50 per cent previous related research, or the latest one by Palmeri lower in the group with high orgasmic frequency than et al54 in America. in the group with low orgasmic frequency. Epidemiological study: The case-crossover methods Besides these two cohort studies, there were three and cohort studies in recent years provided quantitative case-crossover studies in post MI patients conducted data on whether sexual activity is a risk factor, offering by Myocardial Infarction Onset Study (MIOS)59, more reliable evidence (Table III).
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Reprint requests: Prof. Xuerui Tan, the First Affiliated Hospital of Shantou University Medical College Shantou, Guangdong 515 041, China



Harvard Journal of Law & Technology Volume 24, Number 2 Spring 2011 REVERSE SETTLEMENTS AS PATENT INVALIDITY SIGNALS Gregory Dolin, M.D.* TABLE OF CONTENTS I. INTRODUCTION .282 II. THE HATCH-WAXMAN ACT .286 A. The Structure and Purposes of the Act . 286 B. The Mechanics of the Hatch-Waxman Act. 290 III. REVERSE SETTLEMENTS .293

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