Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “atrial function”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,783 records · Page 99Linked to original sources
PubMed1994

Diagnosis of ventricular tachycardia using a pacemaker Holter function.

The diagnosis of ventricular tachycardia (VT) using the Holter function of an implanted pacemaker has not yet been reported. We present the case of a patient with episodes of slow VT, hemodynamically stable, but in whom long lasting attacks were not identified by the patient as VT recurrences, finally leading to progressive heart failure. Prospective analysis of the 24-hour ECG and comparison with the pacemaker Holter data allowed us to determine diagnostic criteria to recognize VT using the pacemaker Holter function. Using these criteria it was possible to retrospectively diagnose VT occurrence during the weeks when the patient was out-of-hospital.

Aged↗
PubMed1991

[Morphofunctional characteristics of cadmium-induced arterial hypertension].

Chronic (12 weeks) peroral administration of cadmium chloride to albino rats in a dose of 2.5 mg/100 g body weight results in arterial hypertension characterized by the increase in systolic blood pressure up to 148 +/- 1.8 mm Hg (vs. 115.4 +/- 1.5 mm Hg in the control animals); the increase in vascular resistance, left ventricular cardiomyocyte hypertrophy, as well as by hypertrophy of arterial walls, the decrease in the ventricular index, the activation of synthesizing function of atrial endocrine cardiomyocytes; enhanced secretion of ANP; a more than two-fold increase in plasma myoglobin concentration, as well as by the development of cadmium-induced nephropathy. In the rehabilitation period (9 weeks) a relatively quick fall in the blood pressure is observed, as well as morphological features of myocardial and renal function recovery, suggesting the nonpersistent nature of cadmium-induced hypertension.

Animals↗
PubMed2005

Benign outcome in a long-term follow-up of patients with hypertrophic cardiomyopathy in Brazil.

BACKGROUND: Selected patients with hypertrophic cardiomyopathy (HCM) have 3% to 4% annual mortality as compared to only 0.5% to 1.5% in nonselected patients. Our aim was to evaluate survival and prognostic factors in HCM in patients in a tertiary care center. METHODS: From 1980 to 1997, 214 patients were prospectively studied, with a mean follow-up of 7 years (range 1-25 years); there were 102 male and 112 female patients, aged 37 +/- 16 years (range 3-76 years). All patients had 12-lead electrocardiogram, 24-hour Holter monitor, and surface echocardiography. Univariate analysis was performed for known adverse factors such as young age, family history, syncope, functional class, atrial fibrillation, ventricular hypertrophy, left ventricular outflow tract obstruction, and nonsustained ventricular tachycardia. RESULTS: There were 22 deaths (10%), 15 directly related to HCM (sudden in 11). The cumulative survival rates were 94.5% at 5 years, 91% at 10 years, and 87.9% at 15 years. The annual mortality rate was 1%. Only New York Heart Association functional class III/IV and maximal ventricular wall thickness >30 mm were associated with HCM-related cardiac death. CONCLUSIONS: We concluded that even a referred population of HCM patients may have a relatively benign outcome. Prognosis is related to advanced functional class and degree of left ventricular hypertrophy.

Adolescent↗
PubMed1977

Atrial receptors in the dog and rabbit.

1. Action potentials were recorded from slips of the cervical vagi in anaesthetized dogs and rabbits. Single functional units with atrial patterns of discharge (Paintal Type A, B and intermediate) were obtained and then attempts were made to alter (i.e. convert) their patterns of discharge. Finally the points of origin of these action potentials were located.2. Thirty unselected units were investigated in thirty dogs. Twenty-seven of these were located in the endocardium of the vein-atrial system and the ratio of the type A, type B and intermediate type receptors was 1:16:10; three units were located elsewhere in the chest. Conversion of the pattern of discharge was achieved in twenty of the twenty-seven units; conversion was achieved in the single type A unit.3. In a second series of experiments in dogs, eight Paintal Type A units were selectively studied in fifteen animals. Four of these were located in the endocardium and all were converted. The remaining four were located outside the endocardium and conversion could not be achieved in two of these. Thus in the entire investigation, the ;type A' units which could not be converted were all located at sites other than the atrial endocardium.4. In the corresponding unselected study in the rabbit, eleven units were studied in eleven animals. Nine of these units were located in the atrial endocardium and the ratio of the type A, type B and intermediate type receptors was 2:1:6. Conversion was achieved in both type A units, the sole type B unit and two of the intermediate units. One of the two units found outside the atrial endocardium was a ;type A' unit and could not be converted.5. The present investigation has shown that the atrial receptors with a Paintal Type A pattern of discharge are relatively rare in both dogs and rabbits. Conversion of the pattern of discharge is a relatively common phenomenon. Evidence for the proposition that there is one basic type of atrial receptor whose pattern of discharge is determined by its precise location in the vein-atrial system is discussed.

Action Potentials↗
PubMed1985

Effect of alterations of pleural pressure on cardiac output.

Cardiac output is determined by the interaction of cardiac pump function and the mechanical properties of the peripheral circulation that govern venous return. Increasing pleural pressure impedes peripheral venous return but aids cardiac ejection; on the other hand, decreasing pleural pressure can augment venous return but impedes the emptying of the left ventricle, creating an increase in aortic pressure. Whether a fall in pleural pressure leads to an increase or decrease in cardiac output depends upon the functional state of the heart and its sensitivity to changes in afterload. Understanding the effect of pleural pressure on cardiac output may lead to the development of therapeutic or diagnostic techniques using altered pleural pressure.

Atrial Function↗
PubMed1986

Regional comparison of midwall segment and area shortening in the canine left ventricle.

We used ultrasonic segment length gauges to examine the regional behavior of midwall fibers at different sites around the left ventricular minor axis in 12 anesthetized dogs. In six dogs (group I) with circumferentially oriented midwall gauges, significantly greater shortening of anterior than lateral or posterior wall segments was demonstrated over a range of left ventricular end-diastolic pressures from 2 to 18 mm Hg. Normalized end-diastolic segment lengths increased more in the anterior wall as end-diastolic pressure increased, suggesting that regional differences in diastolic distensibility may in part account for the observed shortening differences. To examine the extent to which shortening of longitudinally oriented fibers of the subendocardium and subepicardium might influence the behavior of the midwall circumferential fibers, we implanted mutually perpendicular midwall gauges circumferentially and longitudinally in the anterior and posterior walls in six dogs (group II). Longitudinal shortening of midwall fibers was negligible at low end-diastolic pressures, but increased significantly at higher end-diastolic pressures. In the anterior wall, there was greater circumferential than longitudinal shortening, whereas, in the posterior wall, shortening was similar in the two directions. Finally, we calculated the midwall area subtended by the mutually perpendicular gauges and found the systolic change in midwall area to be similar for the anterior and posterior walls at all end-diastolic pressures. We conclude that midwall fibers demonstrate considerable nonuniformity of contraction at different sites around the minor axis. This finding may be related in part to regional differences in diastolic distensibility or in functional interactions between fiber layers. Despite these complex regional, directional, and volume dependent differences in midwall segment function, the systolic changes in midwall area did not vary regionally. Thus, different midwall sites around the minor axis circumference appear to have similar overall contributions to the ejection of blood.

Animals↗
PubMed2005

Atrial pacemaker complex preserved radiofrequency maze procedure reducing the incidence of sick sinus syndrome in patients with atrial fibrillation.

BACKGROUND: The Cox maze III procedure can effectively restore sinus rhythm in most patients with permanent atrial fibrillation (AF). However, previous studies have shown that the maze procedure results in significant sinus node dysfunction, and, consequently, a considerable number of patients required postoperative pacemaker implantation. HYPOTHESIS: This study investigates the hypothesis that the modification of the Cox III maze procedure, to avoid injuring the sinus node and the atrial physiologic pacemaker complex, will reduce the incidence of sick sinus syndrome following surgery. METHODS AND RESULTS: This study investigated 71 patients with permanent AF and mitral valve disease who were undergoing concomitant open-heart surgery. Most atrial incisions in the Cox maze III procedure were replaced with radiofrequency ablation, and the intercaval counterablation was moved posterolaterally to avoid injury to the sinus node and atrial pacemaker complex. At a mean (+/- SD) follow-up time of 46.5 +/- 24 months, 59 patients (83.1%) regained sinus rhythm without receiving antiarrhythmic drug therapy or undergoing electrical cardioversion. The transmitral atrial wave was observed in 44 patients (62%), and the transtricuspid atrial wave was also observed in 53 patients (74.6%). Late sinus node dysfunction developed in only two patients (2.8%), who received permanent pacemaker implantation. CONCLUSION: This modified radiofrequency maze procedure produces few patients with sick sinus syndrome and effectively restores sinus rhythm and atrial transport function in most patients with permanent AF undergoing concomitant open-heart surgery.

Atrial Fibrillation↗
PubMed1996

How useful is thyroid function testing in patients with recent-onset atrial fibrillation? The Canadian Registry of Atrial Fibrillation Investigators.

BACKGROUND: Patients with recent-onset atrial fibrillation often undergo routine thyroid function screening to rule out thyroid disease as a cause of atrial fibrillation. METHODS: Patients with recent (< 3 months) onset of documented atrial fibrillation or flutter were enrolled in the Canadian Registry of Atrial Fibrillation from outpatient clinics, emergency departments, and hospital wards across Canada. Seven hundred twenty-six patients underwent baseline thyroid function screening and were assessed for presence of clinical thyroid disease. Serum thyrotropin level (TSH) was measured in 707 patients (97%), and thyroxine level (T4) in 407 patients (56%). RESULTS: A TSH level less than 0.1 mU/L was present in 5 patients (0.7%). A TSH level less than normal but more than 0.1 mU/L was present in 34 patients (4.7%). No patient had definite hypothyroidism (TSH > 20 mU/L), but 56 patients (7.7%) had an elevated TSH level that was less than 20 mU/L. During 1.7 years of follow-up, only 7 patients were found to have clinical hyperthyroidism, and 11 patients (1.5%) had hypothyroidism. Logistic regression analysis showed that palpitations (odds ratio, 4.9; 95% confidence interval, 1.7-14.0) and asymptomatic presentation (odds ratio, 5.5; 95% confidence interval, 1.9-16.2) were risk factors for low TSH level, and increasing age (odds ratio, 1.32 every 10 years; 95% confidence interval, 1.01-1.66) was a risk factor for high TSH level. The positive predictive value of palpitations and asymptomatic presentation for low TSH level were 9% and 8%, respectively. CONCLUSIONS: An abnormal TSH level is common in patients with recent-onset atrial fibrillation. However, clinical thyroid disease is uncommon. Routine TSH screening of patients who have atrial fibrillation has a low yield and may be better applied to those patients at higher risk of having undiagnosed clinical thyroid disease.

Atrial Fibrillation↗
PubMed1995

Coronary flow stimulates auricular-ventricular transmission in the isolated perfused guinea pig heart.

In the heart in situ coronary flow stimulates oxygen consumption, glycolytic flux, myocardial contractility, and the release of bioactive substances. Studies have indicated that the coronary flow-enhanced contraction is similar to a hormonelike effect because the enhanced contraction results from an elevation in intracellular free calcium. In fact, if extracellular calcium is raised sufficiently, the contraction amplitude rises and remains constant and independent of coronary flow. We hypothesized that coronary flow could also stimulate other calcium-dependent cardiac functions such as auricular-ventricular (A-V) transmission. This hypothesis was tested in isolated guinea pig hearts perfused at constant flow. Our results show that increases in coronary flow (6-25 ml/min range) decrease the A-V delay solely as a result of reduced propagation time in the A-V node and not in atrial or ventricular propagation. When coronary vascular resistance was altered by dilation (nitroglycerin, bradykinin, nitroprusside, and adenosine) or by constriction (angiotensin II), this dromotropic effect of flow remained the same despite wide changes in perfusing pressure. Also, this dromotropic effect of flow was not altered by energy-altering substrates in the perfusate or by perfusion of adenosine receptor blockers. Furthermore, the effectiveness of flow as a dromotropic stimulus varied inversely with changes in calcium entry caused either by elevation or reduction of extracellular calcium. In addition, enhanced viscosity of the perfusing medium amplifies the positive dromotropic effect of flow. These results suggest that coronary flow is a stimulus that exerts a positive dromotropic effect mediated by shear stress.

Aminophylline↗
PubMed1983

Clinical utility and management impact of M-mode echocardiography.

To determine the clinical utility and management impact of M-mode echocardiography, 182 echocardiograms were analyzed at a university teaching hospital. The physicians who ordered the echocardiograms said that 12 percent provided crucial information that was not available from other tests and that 26 percent resulted in a change in patient management. According to two independent board-certified cardiologist-reviewers, 86 percent of echocardiograms were appropriately ordered, but only 15 echocardiograms (8 percent) were actually needed for a change to a new and appropriate management. According to the reviewers, the 77 Group I M-mode echocardiograms (those ordered to evaluate left ventricular function, left atrial size, potential cardiac sources of emboli, or the possibility of bacterial endocarditis, or those ordered in patients who, according to the ordering physician, had undergone or would undergo catheterization regardless of the results of echocardiography) were less likely than the 105 Group II M-mode echocardiograms (those ordered to evaluate possible mitral valve prolapse, hypertrophic cardiomyopathy, valvular function, or the pericardium) to be ordered appropriately, to provide helpful information, or to provide crucial results. Group I echocardiograms had reviewer-assessed appropriate management impact in only one case (1 percent) compared with a 13 percent rate of management impact for Group II M-mode echocardiograms (p less than 0.01). Although echocardiography can be accurate and valuable with yields similar to those of other noninvasive procedures, 77 (42 percent) of 182 M-mode echocardiograms in this hospital could be predicted at the time of ordering to be in a low-yield group.

Echocardiography↗
PubMed1994

Effects of nicardipine, nitroglycerin, and nitroprusside on left ventricular diastolic function during enflurane anesthesia.

The purpose of this study was to evaluate the effects of nicardipine (NCR), nitroglycerin (NTG), or nitroprusside (SNP) on left ventricular diastolic function during enflurane anesthesia in acutely instrumented dogs. Using echocardiography, time constants for the decline in isovolumic left ventricular pressure (T), stiffness constant (K), diastolic time intervals, and left ventricular filling rates were measured in 21 mongrel dogs during the following conditions: (1) 0% enflurane (control), (2) 3.3% enflurane, (3) intravenous infusion of NCR, 1 microgram/kg/min, NTG, 2 micrograms/kg/min, or SNP, 2 micrograms/kg/min, during 3.3% enflurane, and (4) intravenous infusion of NCR, 2 micrograms/kg/min, NTG, 4 micrograms/kg/min, or SNP, 4 micrograms/kg/min, during 3.3% enflurane. During 3.3% enflurane anesthesia, T and K increased significantly, and left ventricular filling rates decreased. The administration of NCR, NTG, or SNP returned T and K to control levels. Left ventricular rapid filling rate returned toward the control level only with NCR (P < 0.05, NCR v NTG, SNP). It is concluded that the depression of diastolic function during enflurane anesthesia was improved by NCR or other vasodilators. The extent and mechanism of action of these vasodilators might differ, however.

Anesthesia, Inhalation↗
PubMed2004

Mechanisms and predictors of transient left ventricular dysfunction early after successful percutaneous balloon mitral valvuloplasty.

BACKGROUND: The immediate effects of balloon mitral valvuloplasty (BMV) on left ventricular (LV) function in patients with mitral stenosis are still controversial. The aim of this study was to investigate the mechanisms and potential clinical, echocardiographic and hemodynamic predictors of transient LV dysfunction occurring in patients with mitral stenosis early after successful percutaneous BMV. METHODS: Sixty patients without residual mitral regurgitation were divided into two groups according to the changes in the left atrial (LA) pressure 15 min after successful BMV: 18 patients (group A) did not present with any reduction in LA pressure, and underwent nitroglycerin administration (0.4 mg, sublingually). The remaining 42 patients (group B) presented with a decrease in LA pressure. RESULTS: At baseline, both the mitral valve gradient and area assessed at echocardiography and during cardiac catheterization were similar in groups A and B. Group A patients presented with, however, higher LV early- and end-diastolic pressures and peak V waves during cardiac catheterization both prior to and 15 min after BMV than group B patients (all p values < 0.05). In group A, nitroglycerin administration was associated with a decrease in LV end-diastolic pressure (p = 0.049), LA pressure (p < 0.001), and peak V wave (p < 0.001) that was still persistent 30 min after its administration, reaching values similar to those observed in group B early after BMV. At multivariate analysis, the only independent predictors of LV dysfunction early after BMV were found to be LV early- (p = 0.015) and end-diastolic (p = 0.023) pressures at baseline and the Wilkins' score (p = 0.004). CONCLUSIONS: After successful BMV a transient lack of LV adaptation to the increased LV preload resulting in a persistently elevated LA pressure is predicted by higher baseline LV diastolic filling pressures and higher Wilkins' scores. It is promptly and steadily reversed by nitroglycerin administration through a transient LV unloading, thus allowing a correct hemodynamic evaluation of the immediate results of the procedure.

Analysis of Variance↗
PubMed1988

Plasma atrial natriuretic peptide in states of altered thyroid function.

To examine a possible role of atrial natriuretic peptide (ANP) in water and electrolyte disturbances associated with thyroid disorders, plasma ANP levels were studied in patients with hyper- and hypothyroidism. In 5 of the 21 hyperthyroid patients, including two patients with atrial fibrillation and two patients with mild cardiomegaly, the plasma ANP concentration was increased when compared to normal subjects. After treatment with methimazole or propylthiouracil, the plasma ANP concentration fell to normal in 4 patients, while it remained high in one patient who had persistent atrial fibrillation. No significant correlation was found between plasma ANP and the heart rate in untreated hyperthyroid patients. Plasma ANP was within the normal range in all 8 patients with hypothyroidism. During treatment with T4, the plasma ANP concentration increased in 6 of the 7 patients. Chest X-ray films and ultrasonic echocardiography demonstrated pericardial effusion in 4 of these patients before therapy. A weak but significant correlation was found between the plasma ANP and T4 concentration, and between plasma ANP and free T4 in hyper- and hypothyroid patients before and after treatment. These results indicate that abnormalities in ANP dynamics in thyroid disorders may probably be caused by hemodynamic changes resulting from a thyroid hormone excess or deficiency.

Adolescent↗
PubMed1998

Effect of L-carnitine on myocardial metabolism: results of a balanced, placebo-controlled, double-blind study in patients undergoing open heart surgery.

The effects of L-carnitine on cardiac performance after open heart surgery were evaluated in a balanced, placebo-controlled, double-blind study in 38 patients. Preoperative haemodynamic status was good in all of them. Seventeen subjects underwent mitral valve replacement and 19 patients coronary artery bypass grafting. Five grams L-carnitine were given intravenously over 2 h, twice daily for 5 consecutive days; moreover, 10 g L-carnitine in 1500 ml cardioplegia were administered through the aortic root after aortic cross-clamping. Surgery was always planned on treatment day 3. The post-ischaemic functional recovery of the heart was assessed by clinical parameters, as well as by biochemical and ultrastructure evaluations on biopsy specimens. No differences were found between the control and the treatment group with respect to all clinical parameters of cardiac performance after cardiopulmonary bypass. At anaesthesia induction, serum carnitine was significantly increased in treated patients, but carnitine concentrations in the right atrial biopsy obtained just before aortic declamping were similar in the two groups. In patients with mitral valve replacement, L-carnitine therapy was associated with significantly higher concentrations of pyruvate, ATP and creatine phosphate in papillary muscle. Glycogen levels were also higher in the treated group, but the difference was not statistically significant. Myocardial ultrastructure on septal biopsies, obtained within 5 min from weaning from extracorporeal circulation, showed better preservation scores for all considered parameters (nucleus, sarcoplasmic reticulum, mitochondria and cellular oedema) in the treated subjects, although the difference reached statistical significance only for nuclei. When biochemical and ultrastructural data are considered, these findings suggest that L-carnitine improves myocardial metabolism. However, it cannot be concluded that L-carnitine provides an advantageous support therapy for well-compensated patients requiring cardiac surgery. In contrast, the positive effects of L-carnitine on cardiac recovery after bypass might become clinically relevant in the surgical setting for haemodynamically compromised patients, in which further investigations are required.

Aged↗
PubMed1989

Ion channels and G proteins.

Newly discovered relationships offer insight into the mechanisms by which extracellular signals produce complex cellular responses. Ion channels, serving crucial cellular functions, are now known to be gated by G proteins directly (by membrane-delimited processes) and indirectly (by cytoplasmic second messengers). It also appears that a G protein may act on several effectors.

Acetylcholine↗
PubMed2002

[Comparative characteristics of systemic and pulmonary hemodynamics during changes in the heart preloading].

A greater degree of relative shifts in the systemic arterial pressure in enhancing the right heart pre-load as compared with its diminishing. A primary role of the compensation mechanisms of the enhanced systemic arterial pressure level. The main role in the compensation of integral shifts of the arterial pressure induced by changes in the heart pre-load was shown to belong to the vascular resistance both in the major and the minor circulation circles. An idea of a greater involvement of the capacity function of the vascular bed in the minor circulation circle as compared with that in the major circulation circle in systemic haemodynamic shifts in changes of the heart pre-load, has been advanced.

Animals↗
PubMed1993

Five-year experience with the maze procedure for atrial fibrillation.

Between September 25, 1987, and December 31, 1992, 75 patients (53 men, 22 women; average age, 52 years) underwent the maze procedure for the treatment of atrial fibrillation. Six patients had undergone a previous cardiac operation and 28% underwent concomitant cardiac procedures in addition to the maze procedure. One patient (1.3%) died 10 days after undergoing a combined maze procedure and Morrow procedure for the management of chronic atrial fibrillation and hypertrophic obstructive cardiomyopathy. Postoperative atrial pacemakers were required in 40%: 26% for preoperative sick sinus syndrome and 6% for iatrogenic injury of the sinus node, and 8% had pacemakers in place preoperatively. As of December 31, 1992, 65 patients had been followed up for at least 3 months after operation (range, 3 to 63 months). The maze procedure cured atrial fibrillation, restored atrioventricular synchrony, and preserved atrial transport function in 64 of 65 patients (98%). The procedure has been curative without the need for medications in 58 of 65 patients (89%) and with the need for medications in 6 of 65 (9%), with medications failing in only 1 of the 65 patients (2%). The results support the maze procedure as the treatment of choice in patients with medically refractory symptomatic atrial fibrillation.

Adult↗