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A Ylitalo

Publications and source records attributed to A Ylitalo.

13 recordsLinked to original sources
PubMed2004

Increased pulse pressure is associated with reduced baroreflex sensitivity.

Although pulse pressure (PP), heart rate variability (HRV) and baroreflex sensitivity (BRS) have been shown to predict cardiovascular events and mortality in various populations, their relationships have not been clarified. We examined these associations in two separate population-based samples of healthy middle-aged subjects. In population 1, data were obtained from 149 subjects (71 men and 78 women) aged 35-64 (mean 47.7) years, and in population 2, from 214 subjects (88 men and 126 women) aged 40-62 (mean 50.5) years. Increased 24-h ambulatory PP was related to decreased cross-spectral BRS independent of age and gender (beta=-0.28, P<0.001 for population 1; beta=-0.22, P=0.003 for population 2). This association remained significant when 24-h ambulatory diastolic blood pressure, body mass index, smoking and alcohol intake were added as covariates in the multivariate analysis. Increased ambulatory PP was also associated with increased beat-to-beat systolic arterial pressure variability. Associations between ambulatory PP and HRV were not significant after controlling for age and gender. Our results suggest that elevated PP does not affect overall HRV, but it interferes with baroreflex-mediated control of the heart rate. This association may be due to a common denominator, such as arterial stiffness, for PP and BRS.

Adult↗
PubMed2001

Relation of left ventricular geometry and function to systemic hemodynamics in hypertension: the LIFE Study. Losartan Intervention For Endpoint Reduction in Hypertension Study.

OBJECTIVES: To clarify the relations of systemic hemodynamics to left ventricular (LV) geometric patterns in patients with moderate hypertension and target organ damage. BACKGROUND: LV geometry stratifies risk in hypertension, but relations of LV geometry to systemic hemodynamic patterns in moderately severe hypertension have not been fully elucidated. DESIGN: Cross-sectional case-control study. SETTING: Baseline findings in the echocardiographic substudy of the Losartan Intervention For Endpoint Reduction in Hypertension Study (LIFE) and in a normotensive reference group. PATIENTS/PARTICIPANTS: Nine hundred and sixty-four patients with Stage I-II hypertension and LV hypertrophy by Cornell voltage duration criteria ((SV3 + RaVL [+ 6 mm in women]) x QRS > 2440 mm x ms) or modified Sokolow- Lyon voltage criteria (SV1 + RV5/RV6 > 38 mm), and 366 apparently normal adults. INTERVENTIONS: None. METHODS: Two-dimensional and Doppler echocardiograms were used to classify hypertensive patients into groups with normal geometry, concentric remodelling and concentric and eccentric hypertrophy, and to measure stroke volume (SV), cardiac output, peripheral resistance and pulse pressure/SV as a measure of arterial stiffness. Comparisons were adjusted for covariates by general linear model with the Sidak post-hoc test RESULTS: Mean SV was higher in patients with eccentric hypertrophy (83 ml/beat) and lower with concentric remodeling (68 ml/beat) than in normal adults (73 ml/ beat). Cardiac output was highest in patients with eccentric LV hypertrophy and lower with concentric remodeling than eccentric hypertrophy; mean pressure and peripheral resistance were equally high in all hypertensive subgroups, whereas pulse pressure/SV was most elevated (by a mean of 47% versus reference subjects) with concentric remodeling and least so (mean + 15%) with eccentric hypertrophy. In multivariate analysis (Multiple R + 0.68), LV mass was independently related to higher systolic pressure, older age, SV, male gender and body mass index (all P< 0.001). Relative wall thickness was independently related (Multiple R + 0.50) to older age, higher systolic pressure, lower SV (all P< 0.001) and higher body mass index (P + 0.007). SV and cardiac output were lower in patients with low stress-corrected midwall shortening. CONCLUSION: In patients with moderate hypertension and ECG LV hypertrophy, the levels of SV and pulse pressure/ SV, are associated with, and may be stimuli to different LV geometric phenotypes.

Adult↗
PubMed2000

Effectiveness of amiodarone as a single oral dose for recent-onset atrial fibrillation.

The efficacy of amiodarone has been proved in long-term maintenance of sinus rhythm (SR) in patients with paroxysmal atrial fibrillation (AF). The present study evaluates the efficacy and safety of a single oral dose of amiodarone in patients with recent-onset AF (<48 hours). Seventy-two patients were randomized to receive 30 mg/kg of either amiodarone or placebo. Conversion to SR was verified by 24-hour Holter monitoring. Ten patients were excluded because of SR in the beginning of monitoring or technical failure during Holter monitoring. The remaining study groups were comparable (n = 31 for each), except that in the placebo group beta blockers were more common. The patients receiving amiodarone converted to SR more effectively than those receiving placebo (p<0.0001). At 8 hours, approximately 50% of patients in the amiodarone group and 20% in the placebo group (Holter successful) had converted to SR, whereas after 24 hours the corresponding figures were 87% and 35%, respectively. The median time for conversion (8.7 hours for amiodarone and 7.9 hours for placebo) did not differ in the groups. Amiodarone was hemodynamically well tolerated, and the number of adverse events in the study groups was similar. Amiodarone as a single oral dose of 30 mg/kg appears to be effective and safe in patients with recent-onset AF.

Administration, Oral↗
PubMed2000

Baroreflex sensitivity and variants of the renin angiotensin system genes.

OBJECTIVES: Because the renin-angiotensin-aldosterone system (RAS) modifies cardiovascular autonomic regulation, we studied the possible associations between baroreflex sensitivity (BRS) and polymorphism in the RAS genes. BACKGROUND: Wide intersubject variability in BRS is not well explained by cardiovascular risk factors or life style, suggesting a genetic component responsible for the variation of BRS. METHODS: Baroreflex sensitivity as measured from the overshoot phase of the Valsalva maneuver and genetic polymorphisms were examined in a random sample of 161 women and 154 men aged 41 to 61 years and then in an independent random cohort of 29 men and 37 women aged 36 to 37 years. An insertion/deletion (I/D) polymorphism of angiotensin-converting enzyme (ACE), M235T variants of angiotensinogen (AGT) and two diallelic polymorphisms in the gene encoding aldosterone synthase (CYP11B2), one in the promoter (-344C/T) and the other in the second intron, were identified by polymerase chain reaction. RESULTS: In the older population, BRS differed significantly across CYP11B2 genotype groups in women (10.1 +/- 4.5, 8.7 +/- 3.8 and 7.1 +/- 3.2 ms x mm Hg(-1) in genotypes -344TT, CT and CC, respectively, p = 0.003 and 11.1 +/- 4.4, 8.9 +/- 4.1 and 7.5 +/- 3.4 ms x mm Hg(-1) in intron 2 genotypes 1/1, 1/2 and 2/2, respectively, p = 0.002), but not in men. No comparable associations were found for BRS with the I/D polymorphism of ACE or the M235T variant of AGT. In the younger population, BRS was even more strongly related to the CYP11B2 promoter genotype (p = 0.0003). The association was statistically significant both in men (p = 0.015) and in women (p = 0.03). CONCLUSIONS: Common genetic polymorphisms in the aldosterone synthase (CYP11B2) gene is associated with interindividual variation in BRS.

Adult↗
PubMed1999

Heart rate variability and occurrence of ventricular arrhythmias during balloon occlusion of a major coronary artery.

Experimental studies suggest that autonomic mechanisms are important in the genesis of ischemia-induced malignant ventricular arrhythmias, but the role of the autonomic nervous system in human arrhythmogenesis is not well known. To assess whether heart rate variability (HRV) predicts the occurrence of ventricular arrhythmias during acute coronary artery occlusion, we performed continuous electrocardiographic, heart rate, and blood pressure recordings before and during a 2-minute balloon occlusion of a stenotic coronary artery in 252 patients with no baseline ventricular premature complexes (VPCs). The ranges of nonspecific responses in heart rate and blood pressure were determined by analyzing a control group of 19 patients with no ischemia during a 2-minute balloon inflation in a totally occluded coronary artery. Balloon occlusion of a coronary artery was stopped because of complex, i.e., bigeminal or repetitive, VPCs in 14 patients, and solitary (<5) VPCs were observed in an additional 19 patients. During coronary occlusion, HRV increased (p <0.001) and heart rate decreased (p <0.05) in patients with no VPCs, whereas an opposite tendency to reduction in HRV (p = 0.08) was observed in patients with complex VPCs. Complex VPCs were observed in 5 (42%) of the 12 patients with a significant coronary occlusion-induced decrease in HRV, in 7 (3.5%) of 200 patients with no change in HRV, but in none of the 40 patients with a significant increase in HRV (p <0.001). Baseline HRV did not predict the occurrence of VPCs during coronary occlusion. Logistic regression analysis identified the decrease in HRV (p <0.001) to be the only independent predictor of complex VPCs. In conclusion, coronary occlusion-induced increase in HRV seems to protect against occurrence of complex ventricular arrhythmias during the early phase of abrupt coronary occlusion, suggesting that vagal activation may modify the outcome of acute coronary events in patients with coronary artery disease.

Blood Pressure↗
PubMed1999

Effects of combination antihypertensive therapy on baroreflex sensitivity and heart rate variability in systemic hypertension.

Earlier studies have shown that cardiovascular autonomic regulation is impaired in untreated or poorly controlled systemic hypertension. The purpose of this double-blind, randomized parallel trial was to evaluate whether improved blood pressure (BP) control can reverse this impairment. The study group consisted of 33 patients (age 45 to 63 years) with poor BP control who received randomized metoprolol or enalapril monotherapy. Baroreflex sensitivity (BRS) was assessed by phenylephrine test and time- and frequency-domain measurements of heart rate variability (HRV) were analyzed from 24-hour ambulatory electrocardiographic recordings during monotherapy and after 10 weeks of combination therapy with metoprolol + felodipine or enalaril + hydrochlorothiazide to lower casual BP to < 140/90 mm Hg. Intensified treatment decreased 24-hour systolic and diastolic BP from 139 +/- 12/86 +/- 8 mm Hg to 126 +/- 8/80 +/- 7 mm Hg (p <0.0001). BRS improved from 6.2 +/- 3.2 ms/mm Hg to 8.9 +/- 4.1 ms/mm Hg (p <0.0001) and measurements of HRV (e.g., SD of all RR intervals from 128 +/- 45 ms to 145 +/- 46 ms, p <0.001) improved significantly during the combination therapy. Changes in BRS and HRV were similar in magnitude in both treatment arms. Mean RR intervals were comparable before and after intensive antihypertensive therapy (850 +/- 124 ms vs 937 +/- 279 ms, p = NS). These data indicate that adequate BP control with modem antihypertensive combination therapy can improve cardiovascular autonomic function, which may partially explain the reduced cardiac mortality observed in patients with intensified antihypertensive therapy.

Aged↗
PubMed1998

Arterial baroreflex impairment in patients during acute coronary occlusion.

OBJECTIVES: We tested whether acute coronary occlusion interferes with arterial baroreceptor control of heart rate in humans. BACKGROUND: Subnormal baroreflex sensitivity (BRS) is an important risk indicator for sudden death. Animal research indicates that both chronic myocardial infarction and acute coronary occlusion impair baroreflex modulation of heart rate. METHODS: We measured RR interval prolongation after phenylephrine-induced systolic pressure increases before and during 2-min coronary occlusions in 47 patients (27 men) undergoing clinically indicated single-vessel coronary angioplasty for stenoses in the proximal or midportion of the vessel causing >50% reduction in the arterial diameter, with normal antegrade flow (33 anterior descending, 10 circumflex, 4 right coronary artery). A control group of 11 patients treated for chronic total occlusion of a coronary artery was assessed to evaluate nonspecific changes in baroreflex function during a 2-min balloon inflation in the occluded artery. RESULTS: The BRS decreased from 5.2+/-3.8 (mean+/-SD) to 4.1+/-3.5 ms x mm Hg(-1) (p=0.01) during the coronary occlusion in the 28 patients with preserved arterial baroreceptor control of heart rate-that is, adequate blood pressure responses and correlation coefficients of the slopes both in baseline and during coronary occlusion. The same phenylephrine dose increased systolic pressure less during than before coronary artery occlusion (21+/-21 versus 36+/-16 mm Hg, p < 0.0001), and in 6 patients it failed to prevent systolic pressure reduction during occlusion. Correlation coefficients of the baroreflex regressions decreased from 0.81+/-0.27 to 0.47+/-0.44 (p < 0.0001) during coronary artery occlusion in the 41 patients with adequate systolic pressure rises in both phenylephrine tests, and the association between RR intervals and rising systolic pressures was lost in 13 patients during coronary occlusion. Balloon inflation in a chronic total occlusion of a coronary artery did not cause significant changes in BRS (from 5.3+/-4.0 to 5.2+/-3.7 ms x mm Hg(-1)), correlation coefficient of the slope or phenylephrine-induced pressure rise. CONCLUSIONS: Our study shows that abrupt coronary occlusion impairs baroreflex modulation of vagal and sympathetic nervous outflow in humans.

Acute Disease↗
PubMed1997

Baroreflex sensitivity in drug-treated systemic hypertension.

Baroreflex sensitivity is impaired in patients with systemic hypertension. The persistence of abnormal baroreflex sensitivity despite adequate blood pressure control may be one of the reasons why the effect of antihypertensive therapy on coronary artery disease mortality has been less than expected on the basis of the achieved blood pressure levels.

Adult↗
PubMed1996

Heart rate variability in systemic hypertension.

Low heart rate (HR) variability is a risk factor for cardiac mortality in various patient populations, but it has not been well established whether patients with long-standing hypertension have abnormalities in the autonomic modulation of HR. Time and frequency domain measures of HR variability were compared in randomly selected, age-matched populations of 188 normotensive and 168 hypertensive males (mean age 50 +/- 6 years for both). The standard deviation of the RR intervals was lower in the hypertensive subjects than in the normotensive ones (52 +/- 19 vs 59 +/- 20 mss; p <0.01), and the very low and low-frequency spectral components of HR variability analyzed as absolute units were reduced in the hypertensive patients relative to the normotensive controls (p <0.001 for both). Hypertensive subjects also had blunted changes of the normalized low- and high-frequency components in response to an upright (sitting) posture (NS) as compared with normotensive subjects (p <0.001 for both). Multiple regression analysis showed the standard deviation of the RR intervals to be predicted most strongly by systolic blood pressure, both in the patients with hypertension (beta--0.20, p=0.01) and in the normotensive subjects (beta--0.28, p=0.0002). After adjustment for the baseline differences in blood pressure and body mass index, none of the absolute measures of the HR variability or the responses of the normalized units of HR variability to a change in the body posture differed between the hypertensive subjects and normotensive controls. These data show that long-standing hypertension results in reduced overall HR variability and blunted autonomic responses to a change in body posture. Altered autonomic modulation of HR in hypertension is mainly due to elevated blood pressure and obesity in males with long-standing hypertension as compared with normotensive subjects.

Adult↗
PubMed1988

Comparison of the effects of metoclopramide on sympathetic and muscarinic responses after pretreatment with atropine and pirenzepine.

Metoclopramide (0.15 mg/kg i.v.) was administered to seven healthy volunteers after pretreatment with either atropine, pirenzepine or saline. With the i.v. doses of atropine (0.020 mg/kg) and pirenzepine (0.20 mg/kg) used in the study, antimuscarinic activities in serum were comparable for the most part of the study. Atropine induced a pronounced rise in heart rate and a hypotensive blood pressure response in the orthostatic test, whereas heart rate was significantly lower after pretreatment with pirenzepine than after saline, without any significant effects on systolic blood pressure. Plasma noradrenaline but not plasma adrenaline response to upright posture was increased after metoclopramide following saline but it was reduced following pirenzepine pretreatment, atropine having no significant effect on plasma noradrenaline response in the orthostatic test. Saliva secretion was lower after atropine than after pirenzepine or saline. Pirenzepine seems to diverge from classical anticholinergic drugs, and it reduces the metoclopramide-induced increase in sympathetic responsivity under conditions where cardiac function is not appreciably affected.

Adult↗
PubMed1986

Differences in cardiac but not in neuroendocrine responses in healthy volunteers after administration of two antimuscarinic agents, atropine and pirenzepine.

Neuroendocrine and cardiac responses were studied in healthy volunteers with the classical muscarinic antagonist, atropine and the new antimuscarinic agent, pirenzepine. The secretion of prolactin (PRL) and growth hormone (GH) was increased after metoclopramide. Typically, an antidopaminergic drug such as metoclopramide decreases rather than increases GH concentrations in serum. Pretreatment with both atropine and pirenzepine abolished the increase of GH secretion, which suggests an important role of cholinergic mechanisms in the regulation of GH secretion. The increase of PRL secretion was not inhibited by the two muscarinic antagonists. With the doses used, antimuscarinic activities in serum were comparable after atropine and pirenzepine treatments for the most part of the study. Heart rate was, however, significantly increased during atropine and higher than during saline or pirenzepine treatments throughout the study period. When compared to placebo, pirenzepine lowered heart rate slightly but significantly. The exact mechanism of this effect is unclear. We conclude that in contrast to the identical neuroendocrine effects, the cardiac responses clearly differ during atropine and pirenzepine treatments which confirms the ability of pirenzepine to distinguish muscarinic receptor sites in the central nervous system from those of the heart.

Adult↗