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PubMed1980

The changing face of congenital heart disease. A method for predicting the influence of cardiac surgery upon the prevalence and spectrum of congenital heart disease.

The influence of surgery upon the natural history of congenital heart disease is great. Children with many types of congenital heart lesions are now living to adult life. Most of these children will, however, require continuing medical care, care which traditionally has been given by the pediatrician. We have developed a method by which incidence figures and a knowledge of the natural history may be used to obtain prevalence estimates of congenital heart disease. We estimate that in the United States in 1995 there will be nearly 300,000 children under 21 years old with congenital heart disease; 38 per cent of these will have had one or more surgical procedures. In the last two decades the majority of care for children with congenital heart disease was aimed at the correction of the original lesion; however, we predict that in the next two decades an increasing fraction of medical resources will be directed toward the residua and sequelae of cardiac surgical procedures. This alteration in character of congenital heart disease will affect the patient mix seen by the cardiologist with adult patients as well as that of the pediatrician. For ventricular septal defect, pulmonary stenosis, atrial septal defect, persistent ductus arteriosus, coarctation of the aorta and tetralogy of Fallot, we have estimated the nationwide prevalence and the surgical requirements for 1995. Used with more specific local data on population and birth rate, this model can provide important input into planning the delivery of cardiovascular services.

Adolescent↗

PubMedDate not supplied

Differential effects of heart rate modification training on college students, older males, and patients with ischemic heart disease.

Seventy male subjects participated in a six session study of feedback-mediated heart rate modification. Three groups of subjects were compared: (1) college students, (2) patients with ischemic heart disease, and (3) healthy males, age-matched to the patients. The groups did not differ in heart rate during rest or in response to a perceptual-motor tracking task. However, the college students produced significantly larger changes in cardiac rate than the other two groups when instructed to modify heart rate (speed or slow) and provided with exteroceptive feedback. The patients showed the poorest overall feedback performance. These differences between groups were greater for speeding than for the slowing task. Relationships were explored between feedback performance and resting heart and respiration rate, drug regime, and personality questionnaires. The results were consistent with the hypothesis that interdependence between psychological stimuli and cardiovascular events is reduced in heart disease.

Adult↗

PubMed1999

Management of acute right heart failure after combined heart and kidney transplantation: case report.

Combined heart and kidney transplantation is performed rarely and merits unique fluid-management considerations postoperatively. We present the case of a young man who developed acute right heart failure after combined heart and kidney transplantation and responded to hemofiltration. We believe that the postoperative management of combined heart and kidney transplant recipients should not be different from that of patients receiving a heart transplant only. Intravenous fluids should be administered judiciously, and hemofiltration should be instituted early to remove fluid and reduce preload if right heart failure develops.

Acute Disease↗

PubMedDate not supplied

Deaths from ischemic heart disease in persons aged 65 or younger in Helsinki in 1970 with special reference to patho-anatomic findings in hearts.?211.

Deaths from ischemic heart disease(IHD) occurring during a period of one year in Helsinki in persons aged 65 years or younger have been investigated by the Ischaemic Heart Disease Register. Altogether 526 fatalities were registered. Autopsy data were collected in 432 cases, the autopsy rate being 82 percent. The results are presented separately for persons autopsied in the pathologic departments, representing mostly delayed deaths in hospitals, and for medico-legally autopsied persons representing sudden deaths outside hospitals. The diagnosis of IHD death was either based on the positive patho-anatomic or clinical evidence of an acute heart attack or supported by a history of clinical IHD in 92 percent of all registered fatal cases. In the remaining fatalities the possibility of other causes of death had been more or less definitely excluced. All persons with an acute attack of IHD and all autopsied cases showed a division into four socio-economic groups very similar to that of the population of Helsinki. Men belonging to the lowest social group were over-represented among medico-legally autopsied cases. A history of a previous heart disease, visits to a doctor and the use of digitalis were less common in persons autopsied medico-legally than in those autopsied in the pathologic departments. In the former an acute infarction was most often located in the posterior wall and in the latter in the anterior wall of the left ventricle. The prevalence of an occlusion was highest in the right coronary artery in the former and in the left anterior descending coronary artery in the latter; In medico-legally autopsied cases in which a recent myocardial infarction was observed the interventricular septum was involved in 81 percent, but in cases with an old infarction the septum was involved in only 52 percent. No difference in the size of the hearts, the frequency of an old infarction or the prevalence of coronary occlusions was found between persons autopsied in the pathologic and forensic departments. Although a previous angina was about equally common in both sexes, old infarctions were more common in men. The increase in heart weight had occurred proportionally to the same extent in both sexes.

Acute Disease↗

PubMed1983

Variation in virulence of Coxsackie virus B3 in the hearts of mice. I. Comparison of mortality and virus growth in the heart and other organs.

Virulence of Coxsackie virus B3 (CB3) was compared in mice between strain SK-74 isolated from a patient and strain T-70 isolated from a healthy child as well as between prototype strain Nancy and its mouse-passaged derivative strain PMH. Strain SK-74 showed a high mortality (40-80%), while strain T-70 did not induce deaths in mice (mortality: 0%). Strain PMH showed a high mortality (65-85%), but strain Nancy did not cause deaths in the mice. In agreement with the mortality trend, virus titers in the heart and other organs of mice inoculated with strain SK-74 and PMH were higher than those in mice inoculated with T-70 and Nancy strains. Since virus titers in the heart remained higher than those in other organs, the heart was regarded as the main organ in which CB3 could replicate and induce cell degeneration. The present results suggest that a marked variation in virulence in the hearts of mice among CB3 strains occurred and that passage through the hearts of mice enhances the virulence of CB3 in the hearts of mice.

Animals↗

PubMed1991

RR variability and baroreflex sensitivity in patients with ventricular tachycardia associated with normal heart and patients with ischemic heart disease.

Recent studies have suggested that disordered autonomic function, particularly the loss of protective vagal reflexes are associated with an increased incidence of arrhythmic deaths following myocardial infarction (MI). Heart rate variability (HRV) and baroreflex sensitivity (BRS) are measures of myocardial autonomic function and predict arrhythmic deaths post-MI. Patients with ventricular tachycardia associated with a "normal heart" frequently have exercise-induced arrhythmia suggesting that the autonomic nervous system is important in the genesis of this form of ventricular tachycardia (VT). This study examines HRV and BRS in patients with VT associated with a "normal heart" and compares these values to patients post-MI with and without evidence of arrhythmia. Twenty patients with VT associated with a "normal heart," 16 patients with MI but without arrhythmia on follow-up, and 11 patients with MI and VT on follow-up were studied. HRV was measured from 24-hour Holter recordings and BRS was measured from plots of change in systolic blood pressure versus change in heart rate following an intravenous injection of 0.4-0.6 mg phenylephrine. HRV was significantly higher in the patients with VT associated with a normal heart (34.2 +/- 10.8 msec) compared to the patients post-MI, without (23.7 +/- 6.7 msec) and with (14.8 +/- 3.8 msec) arrhythmia (F = 9.2, P less than 0.001) and these differences were unaffected by adjustment for age.(ABSTRACT TRUNCATED AT 250 WORDS)

Autonomic Nervous System↗

PubMed2002

Increasing plasma potassium with amiloride shortens the QT interval and reduces ventricular extrasystoles but does not change endothelial function or heart rate variability in chronic heart failure.

OBJECTIVES: To test whether simply increasing plasma potassium with amiloride would exert any of the same beneficial effects on "surrogate outcome measures" that are seen with spironolactone. The latter has been shown to improve mortality in chronic heart failure, possibly as a result of improvements in endothelial dysfunction, vascular angiotensin converting enzyme (ACE), autonomic function, myocardial fibrosis, ventricular arrhythmias, and QT interval indices. DESIGN: Randomised, placebo controlled trial. SETTING: Teaching hospital. PATIENTS AND INTERVENTIONS: Double blind crossover study involving 10 patients with New York Heart Association functional class II-III chronic heart failure comparing 5 mg/day amiloride (one month) with placebo. MAIN OUTCOME MEASURES: Endothelial function, vascular ACE, collagen markers, 24 hour ECG, and QT interval results. RESULTS: The amiloride induced increase in serum potassium (0.4 mmol/l) did not significantly change endothelial dysfunction, vascular ACE, collagen markers, or heart rate variability. However, amiloride significantly improved QT interval indices, reducing both QT dispersion (from 65.7 ms to 50.9 ms, p = 0.001) and mean maximal corrected QT (from 445 ms to 435 ms, p = 0.008). Amiloride also reduced ventricular extrasystoles (p < 0.05). CONCLUSIONS: Amiloride shortens QT interval length and reduces ventricular extrasystoles in chronic heart failure, implying that this effect is caused by potassium retention per se. However, unlike spironolactone, amiloride did not improve endothelial dysfunction, vascular ACE, heart rate variability, or myocardial fibrosis, implying that spironolactone improves these latter effects by aldosterone blockade rather than by simply increasing serum potassium. Therefore, amiloride has fewer beneficial mechanistic effects than spironolactone, but it does share with spironolactone the ability to shorten the QT interval and reduce ventricular extrasystoles.

Aged↗

PubMed2002

Grown-up congenital heart (GUCH) disease: current needs and provision of service for adolescents and adults with congenital heart disease in the UK.

This report addresses the needs and problems of grown-up congenital heart (GUCH) patients and makes recommendations on organisation of national medical care, training of specialists, and education of the profession. The size of the national population of patients with grown-up congenital heart disease (GUCH) is uncertain, but since 80-85% of patients born with congenital heart disease now survive to adulthood (age 16 years), an annual increase of 2500 can be anticipated according to birth rate. Organisation of medical care is haphazard with only three of 18 cardiac surgical centres operating on over 30 cases per annum and only two established specialised units fully equipped and staffed. Not all grown-ups with congenital heart disease require the same level of expertise; 20-25% are complex, rare, etc, and require life long expert supervision and/or intervention; a further 35-40% require access to expert consultation. The rest, about 40%, have simple or cured diseases and need little or no specialist expertise. The size of the population needing expertise is small in comparison to coronary and hypertensive disease, aging, and increasing in complexity. It requires expert cardiac surgery and specialised medical cardiology, intensive care, electrophysiology, imaging and interventions, "at risk" pregnancy services, connection to transplant services familiar with their basic problem, clinical nurse specialist advisors, and trained nurses. An integrated national service is described with 4-6 specialist units established within adult cardiology, ideally in relation or proximity to university hospital/departments in appropriate geographic location, based in association with established paediatric cardiac surgical centres with designated inpatient and outpatient facilities for grown-up patients with congenital heart disease. Specialist units should accept responsibility for educating the profession, training the specialists, cooperative research, receiving patients "out of region", sharing particular skills between each other, and they must liaise with other services and trusts in the health service, particularly specified outpatient clinics in district and regional centres. Not every regional cardiac centre requires a full GUCH specialised service since there are too few patients. Complex patients need to be concentrated for expertise, experience, and optimal management. Transition of care from paediatric to adult supervision should be routine, around age 16 years, flexibly managed, smooth, and explained to patient and family. Each patient should be entered into a local database and a national registry needs to be established. The Department of Health should accept responsibility of dissemination of information on special needs of such patients. The GUCH Patients' Association is active in helping with lifestyle and social problems. Easy access to specialised care for those with complex heart disease is crucial if the nation accepts, as it should, continued medical responsibility to provide optimal medical care for GUCH patients.

Adolescent↗

PubMed2003

Pericardial effusion after open heart surgery for congenital heart disease.

OBJECTIVES: To determine the prevalence and time course of pericardial effusion after open heart surgery for congenital heart diseases and to identify predisposing risk factors. DESIGN AND PATIENTS: Prospective assessment of development of pericardial effusion in 336 patients (163 males) undergoing open heart surgery for congenital heart disease by serial echocardiography on days 5, 7, 14, 21, and 28 postoperatively. SETTING: Tertiary paediatric cardiac centre. RESULTS: The prevalence of pericardial effusion was 23% (77 of 336). Of the 77 patients who developed effusion, 43 (56%) had moderate to large effusions and 18 (23%) were symptomatic. Patients who had a large amount of effusion were more likely to be symptomatic than those with only a small to moderate amount (47.4% v 15.5%, p = 0.01). The mean (SD) onset of pericardial effusion was 11 (7) days after surgery, with 97% (75 of 77) of cases being diagnosed on or before day 28 after surgery. The prevalence of effusion after Fontan-type procedures (60%, 6 of 10) was significantly higher than that after other types of cardiac surgery: repair of left to right shunts (22.1%, 43 of 195), repair of lesions with right ventricular outflow tract obstruction (22.6%, 19 of 84), arterial switch operation (6.7%, 1 of 15), and miscellaneous procedures (25%, 8 of 32) (p = 0.037). Univariate analyses showed that female patients (p = 0.009) and those receiving warfarin (p = 0.002) had increased risk of postoperative pericardial effusion. A greater pericardial drain output in the first four hours after surgery also tended to be significant (p = 0.056). Multivariate logistic regression similarly identified warfarin treatment (beta = 1.73, p = 0.009) and female sex (beta for male = -0.63, p = 0.037) as significant determinants. CONCLUSIONS: Pericardial effusion occurs commonly after open heart surgery for congenital heart disease. Serial echocardiographic monitoring up to 28 days postoperatively is indicated in selected high risk patients such as those with symptoms of postpericardiotomy syndrome and those given warfarin.

Analysis of Variance↗

PubMed1986

Heart rate, employment status, and prevalent ischaemic heart disease confound relation between cereal fibre intake and blood pressure.

Cross sectional data from a survey of 2512 men aged 45-49 years were used to examine the confounding effects of heart rate, employment, and ischaemic heart disease (IHD) on the relation between cereal fibre intake and blood pressure. Daily cereal fibre intake (g/day) was associated with systolic pressure (r = -0.053, p less than 0.01), diastolic pressure (r = -0.057, p less than 0.01), and heart rate (r = -0.071, p less than 0.01). The associations were strengthened in employed men and inapparent in unemployed men. Unemployed men had more IHD than employed men. Persons with any manifestation of IHD had significantly higher blood pressure and heart rates but ate less cereal fibre (7.0 v 7.9 g/day, p less than 0.001) than those without IHD, regardless of employment status. In employed men, after adjustment for age, body mass index, prevalent IHD, and heart rate, systolic pressure changed -0.186 mmHg (95% CI = -0.362, -0.009) and diastolic pressure changed -0.111 mmHg (95% CI = 0.228, 0.005) for each gram of cereal fibre eaten daily. The association between cereal fibre and blood pressure was inapparent in unemployed men. Heart rate, employment, and prevalent IHD confound the association between cereal fibre intake and blood pressure. Future work concerning this relationship will have to account for the effects of these variables.

Blood Pressure↗

PubMed1995

Effects of age on intrinsic heart rate, heart rate variability, and AV conduction in healthy humans.

Heart rate, heart rate variability, and atrioventricular (AV) conduction were studied in 20 young (30 +/- 5 yr) and 19 older (69 +/- 7 yr) healthy men and women before and after single and double autonomic blockade (randomized order: atropine, 0.04 mg/kg i.v.; propranolol, 0.2 mg/kg i.v.). Basal R-R intervals did not differ, but older age increased P-R intervals (177 +/- 24 vs. 149 +/- 17 ms, P < 0.001) and decreased SD of R-R (43 +/- 17 vs. 70 +/- 18 ms, P = 0.001) and heart rate spectral content (area under the power vs. frequency curve from 0.04 to 0.32 Hz: 3.01 +/- 2.1 vs. 7.82 +/- 4.8 beats/min2, P < 0.009), as well as postural responses (R-R decreases of 107 +/- 80 vs. 250 +/- 72 ms, P < 0.002). Atropine decreased R-R intervals, SD of R-R, and high-frequency (0.24-0.32 Hz) spectral content less in elderly subjects compared with younger subjects. Propranolol increased R-R and P-R intervals equally in old and young and abolished low-frequency (0.04-0.12 Hz) increases with standing (P < 0.0008). After double blockade, R-R, P-R, and paced AV intervals were longer in old subjects. Mean values were as follows: R-R intervals, 859 +/- 176 vs. 677 +/- 106 ms, P < 0.001; P-R intervals, 179 +/- 23 vs. 149 +/- 17 ms, P = 0.0002; paced P-R intervals (500 ms), 251 +/- 39 vs. 215 +/- 47 ms; and AV block cycle length, 413 +/- 51 vs. 385 +/- 69 ms (multivariate analysis of variance, P < 0.03). After double autonomic blockade, heart rate variability was nearly eliminated in young and old (reduced > 98%, P < 0.0001). We conclude that age differences in heart rate variability can be explained by autonomic influences, but heart rate and AV conduction differences exist independently of beta-adrenergic and/or parasympathetic influences.

Adult↗

PubMed1992

Heart energetic efficiency in O2-exposed rats studied in isolated working heart.

Death in normobaric hyperoxia was related in the past to pulmonary insufficiency of the edematous lung. However, high arterial O2 tension on final collapse led to the suggestion that the heart and not the lung is the first organ that fails. We measured aortic flow, coronary flow, left ventricular pressure, affluent and effluent PO2, PCO2, and pH in the working heart excised from control and normobaric O2-exposed rats (51-63 h). The oxygen consumption (VO2) of experimental hearts was not different from control, but mechanical power output (PVAP) (calculated from pressure-volume area) was reduced as a function of O2 exposure time. Myocardial contractility indexes, maximal elastance and maximal time derivative of pressure, increased as a function of O2 exposure time, being below control values after 50 h and above control values after 60 h. The individual slopes for the regression of VO2 vs. PVAP rose as a function of exposure time from values below control after 50 h exposure to values above control after 60 h. Energetic efficiency (PVAP/VO2) decreased as a function of O2 exposure time and points to possible heart failure in the intact animal. After 50 h O2 exposure the heart was energetically more efficient than the control. Possible changes in the heart are discussed.

Air Pressure↗

PubMedDate not supplied

Failure of platelet parameters and biomarkers to correlate platelet function to severity and etiology of heart failure in patients enrolled in the EPCOT trial. With special reference to the Hemodyne hemostatic analyzer. Whole Blood Impedance Aggregometry for the Assessment of Platelet Function in Patients with Congestive Heart Failure.

Data from small studies have suggested the presence of platelet abnormalities in patients with congestive heart failure (CHF). We sought to characterize the diagnostic utility of different platelet parameters and platelet-endothelial biomarkers in a random outpatient CHF population investigated in the EPCOT ('Whole Blood Impedance Aggregometry for the Assessment of Platelet Function in Patients with Congestive Heart Failure') Trial. Blood samples were obtained for measurement of platelet contractile force (PCF), whole blood aggregation, shear-induced closure time, expression of glycoprotein (GP) IIb/IIIa, and P-selectin in 100 consecutive patients with CHF. Substantial interindividual variability of platelet characteristics exists in patients with CHF. There were no statistically significant differences when patients were grouped according to incidence of vascular events, emergency revascularization needs, survival, or etiology of heart failure. Aspirin use did not affect instrument readings either. PCF correlates very poorly with whole blood aggregometry (r(2) = 0.023), closure time (r(2) = 0.028), platelet GP IIb/IIIa (r(2) = 0.0028), and P-selectin (r(2) = 0.002) expression. Furthermore, there was no correlation with brain natriuretic peptide concentrations, a marker of severity and prognosis in heart failure reflecting the neurohumoral status. Patients with heart failure enrolled in the EPCOT Trial exhibited a marginal, sometimes oppositely directed change in platelet function, challenging the diagnostic utility of these platelet parameters and biomarkers to serve as useful tools for the identification of platelet abnormalities, for predicting clinical outcomes, or for monitoring antiplatelet strategies in this population. The usefulness of these measurements for assessing platelets in the different clinical settings remains to be explored. Taken together, opposite to our expectations, major clinical characteristics of heart failure did not correlate well with the platelet characteristics investigated in this study.

Aged↗

PubMed2004

Tracking women's awareness of heart disease: an American Heart Association national study.

BACKGROUND: Cardiovascular disease (CVD) is the leading cause of mortality in men and women in the United States, yet prior research has shown a lack of awareness of risk among women. The purpose of this study was to assess the contemporary awareness, knowledge, and perceptions related to CVD risk among American women and to evaluate trends since 1997, when the American Heart Association initiated a national campaign to improve awareness of CVD among women. METHODS AND RESULTS: A telephone survey of a nationally representative random sample of women was conducted in June and July 2003, with an oversampling of black and Hispanic women; results were compared with those of similar surveys in 2000 and 1997. The present survey included 1024 respondents age > or =25 years; 68% were white, 12% black, 12% Hispanic, and 8% other ethnicities. Awareness, knowledge, and perceptions about heart disease were evaluated by use of a standard interviewer-assisted questionnaire. A shift in awareness of heart disease as the leading killer of women has occurred since 1997. In 2003, 46% of respondents spontaneously identified heart disease as the leading cause of death in women, up from 30% in 1997 (P<0.05) and 34% in 2000 (P<0.05). In contrast, the percentage of women citing cancer as leading cause of death has significantly decreased. Black, Hispanic, and younger women (<45 years old) had lower awareness of heart disease as their leading cause of death than did white and older women. Nearly all women reported comfort in discussing prevention with healthcare providers, but only 38% of women reported that their doctors had ever discussed heart disease with them. CONCLUSIONS: Awareness of CVD has increased, although a significant gap between perceived and actual risk of CVD remains. Educational interventions to improve awareness and knowledge are needed, particularly for minority and younger women.

Adult↗

PubMed2004

Thyrotropin-releasing hormone is induced in the left ventricle of rats with heart failure and can provide inotropic support to the failing heart.

BACKGROUND: We reported previously that left ventricular gene expression for thyrotropin-releasing hormone (TRH) precursor was increased in rats with heart failure 8 weeks after myocardial infarction (MI) and that early ACE inhibition tended to cause further myocardial induction of this gene. METHODS AND RESULTS: Here, we show that after MI, the expression of pro-TRH is induced in the heart coordinately with the protease PC1, an important enzyme in TRH biosynthesis. Pro-TRH gene expression was induced in cardiac interstitial cells after MI, and this effect was restricted to the heart, because no increase in TRH mRNA abundance was observed in the hypothalamus, kidney, or lung. Transcript abundance of pro-TRH can be increased in cultured cardiac fibroblasts by several adrenergic agonists, indicating that the adrenergic axis may play a regulatory role in cardiac TRH production. Acute intravenous administration of TRH to rats with ischemic cardiomyopathy caused a significant increase in heart rate, mean arterial pressure, cardiac output, stroke volume, and cardiac contractility. CONCLUSIONS: Taken together, these results indicate that TRH is specifically induced in the heart after MI and that it can increase cardiac performance in rats with ischemic cardiomyopathy. Thus, in addition to catecholamine and angiotensin II, pro-TRH/TRH may be another important axis that affects hemodynamics and cardiac function in heart failure.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1993

Survival after the onset of congestive heart failure in Framingham Heart Study subjects.

BACKGROUND: Relatively limited epidemiological data are available regarding the prognosis of congestive heart failure (CHF) and temporal changes in survival after its onset in a population-based setting. METHODS AND RESULTS: Proportional hazards models were used to evaluate the effects of selected clinical variables on survival after the onset of CHF among 652 members of the Framingham Heart Study (51% men; mean age, 70.0 +/- 10.8 years) who developed CHF between 1948 and 1988. Subjects were older at the diagnosis of heart failure in the later decades of this study (mean age at heart failure diagnosis, 57.3 +/- 7.6 years in the 1950s, 65.9 +/- 7.9 years in the 1960s, 71.6 +/- 9.4 years in the 1970s, and 76.4 +/- 10.0 years in the 1980s; p < 0.001). Median survival after the onset of heart failure was 1.7 years in men and 3.2 years in women. Overall, 1-year and 5-year survival rates were 57% and 25% in men and 64% and 38% in women, respectively. Survival was better in women than in men (age-adjusted hazards ratio for mortality, 0.64; 95% CI, 0.54-0.77). Mortality increased with advancing age in both sexes (hazards ratio for men, 1.27 per decade of age; 95% CI, 1.09-1.47; hazards ratio for women, 1.61 per decade of age; 95% CI, 1.37-1.90). Adjusting for age, there was no significant temporal change in the prognosis of CHF during the 40 years of observation (hazards ratio for men for mortality, 1.08 per calendar decade; 95% CI, 0.92-1.27; hazards ratio for women for mortality, 1.02 per calendar decade; 95% CI, 0.83-1.26). CONCLUSIONS: CHF remains highly lethal, with better prognosis in women and in younger individuals. Advances in the treatment of hypertension, myocardial ischemia, and valvular heart disease during the four decades of observation did not translate into appreciable improvements in overall survival after the onset of CHF in this large, unselected population.

Age Factors↗

PubMed1996

Impact of reduced heart rate variability on risk for cardiac events. The Framingham Heart Study.

BACKGROUND: Although heart rate variability (HRV) is altered in a variety of pathological conditions, the association of reduced HRV with risk for new cardiac events has not been studied in a large community-based population. METHODS AND RESULTS: The first 2 hours of ambulatory ECG recordings obtained on subjects of the Framingham Heart Study who were free of clinically apparent coronary heart disease or congestive heart failure were reprocessed to assess HRV. Five frequency-domain measures and three time-domain measures were obtained. The associations between HRV measures and the incidence of new cardiac events (angina pectroris, myocardial infarction, coronary heart disease death, or congestive heart failure) were assessed with proportional hazards regression analyses. There were 2501 eligible subjects with a mean age of 53 years. During a mean follow-up of 3.5 years, cardiac events occurred in 58 subjects. After adjustment for age, sex, cigarette smoking, diabetes, left ventricular hypertrophy, and other relevant risk factors, all HRV measures except the ratio of low-frequency to high-frequency power were significantly associated with risk for a cardiac event (P = .0016 to .0496). A one-standard deviation decrement in the standard deviation of total normal RR intervals (natural log transformed) was associated with a hazard ratio of 1.47 for new cardiac events (95% confidence interval of 1.16 to 1.86). CONCLUSIONS: The estimation of HRV by ambulatory monitoring offers prognostic information beyond that provided by the evaluation of traditional cardiovascular disease risk factors.

Adult↗

PubMed1997

Abnormal awake respiratory patterns are common in chronic heart failure and may prevent evaluation of autonomic tone by measures of heart rate variability.

BACKGROUND: Reduced heart rate variability, particularly in the Very-low-frequency (VLF) spectral band, has been found to be a marker for poor prognosis in patients after myocardial infarction, but the origin of the VLF oscillations is unclear. In this study, we demonstrate that the power of cardiovascular oscillations in the VLF band in awake patients with mild to severe chronic heart failure is greatly increased by the common occurrence of unrecognized irregularity of breathing, which may confound the use of heart rate variability measures as indexes of autonomic tone or prognosis. METHODS AND RESULTS: Among 110 consecutive patients referred for consideration of transplantation, 90 were in sinus rhythm, of whom 10 were excluded as unstable. The remaining 80 patients underwent recordings of ECG, beat-to-beat arterial oxygen saturation (SaO2), and respiration during both spontaneous and controlled breathing. During spontaneous awake breathing, 64% showed periodic breathing or Cheyne-Stokes respiration (CSR), which was associated with dominant power in the VLF band of all signals. This VLF power accounted for 55%, 77%, and 87% of heart rate variability, respectively, in patients with normal breathing, periodic breathing, and CSR. It was reduced by 48% and 62%, respectively, during controlled breathing in patients with periodic breathing or CSR. Controlled ventilation also improved oxygen saturation and markedly reduced its variability. CONCLUSIONS: Breathing disorders are surprisingly common in awake patients with poor left ventricular function and produce large VLF oscillations in heart rate variability. If measures of heart rate variability are used for prognostic purposes during both short-term and long-term recordings, the confounding effects of variable respiratory patterns should be excluded. Respiratory rehabilitation might help control potentially hazardous surges in sympathetic tone.

Adult↗