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PubMed2004

Cardiac lipoma: a rare cause of right-to-left interatrial shunt with normal pulmonary artery pressure.

Cardiac lipomas are rare tumors. They usually remain asymptomatic for a long time and cause angina, arrhythmia, dysfunction of the ventricles or valves, and peripheral embolization during the later stages of development. There is little or no information about right-to-left interatrial shunt with normal pulmonary artery pressure, produced as a consequence of the infiltration of the atrial septum, the right atrial wall, and the myocardium because of the presence of fat in patients with platypnea-orthodeoxia syndrome. We present a patient with this syndrome who was identified through transesophageal echocardiography. The study showed a massive right-to-left shunt without pulmonary hypertension, produced by an important cardiac infiltration of adipose tissue that created a narrow passage in the right atrium, and a redirection of the flow to a patent foramen ovale, explaining the pathophysiology of the syndrome.

Aged↗
PubMed1989

Calcitonin gene-related peptide regulates calcium current in heart muscle.

The influx of Ca2+ due to the transmembrane calcium current, ICa, has a fundamental role in cardiac pacemaker activity, in the action potential plateau and in excitation-contraction coupling. Both sympathetic and parasympathetic neurotransmitters can modulate ICa. Recent studies indicate that in both the cardiovascular and the central nervous systems, nerve varicosities exist that contain a novel non-adrenergic, non-cholinergic peptide--calcitonin gene-related peptide (CGRP). Although CGRP is known to exert strong positive inotropic and chronotropic effects, as well as to cause vasodilation, very little is known about the ionic mechanisms of these effects. Here we report that CGRP dramatically increases ICa in single heart cells. Although this CGRP-induced increase in ICa resembles the effect of beta-adrenergic agonists, our results demonstrate some significant differences between the effects of CGRP and these agonists: (1) the increase due to CGRP cannot be blocked by beta-adrenergic antagonists; (2) the CGRP-induced effect is transient; and, (3) CGRP can inhibit isoproterenol-stimulated ICa. Our results provide the first electrophysiological evidence that CGRP can significantly modulate ICa in the heart, and suggest a new additional mechanism for the neurogenic control of cardiac function.

Action Potentials↗
PubMed2000

Mitral flow derived Doppler indices of left ventricular diastolic function in a general population; the Tromso study.

AIMS: Left ventricular diastolic dysfunction has been proposed as the basis of heart failure in patients with normal left ventricular systolic function. Doppler indices of mitral inflow have been widely used to diagnose this condition and have been shown to correlate well with increased left atrial pressure in patients with cardiovascular disease. We wanted to establish age-specific criteria for normality of these indices in a large population and to determine the association of abnormal values to age and cardiovascular disease. METHODS AND RESULTS: In our sample of subjects aged 25-85 years, 3022 had pulsed Doppler measurements of mitral inflow velocities and early inflow deceleration time. The association of these indices to age and gender were established in a 'healthy' reference subsample of 949 subjects. Age-specific percentiles showed a significant decline with increasing age for peak early mitral inflow velocity and the ratio of peak early and atrial inflow velocities (E/A ratio), whereas early inflow deceleration time and peak atrial inflow velocity showed a significant increase with increasing age. According to current criteria for diastolic dysfunction, the prevalence of dysfunction decreases with increasing age in the general population, as well as in the subgroup with cardiovascular disease. Only 7% of the variance in deceleration time was explained by cardiovascular disease or risk factors. For the E/A ratio, however, 41 and 48% of the variance were explained for men and women, respectively. CONCLUSION: Age- and gender-specific criteria for normality are provided. Our data confirm the existence of a significant effect of age and gender on mitral Doppler indices of diastolic dysfunction. However, Doppler criteria for diastolic dysfunction based on these measurements need revision.

Adult↗
PubMed1979

Blood flow in pulmonary veins: I. Studies in dog and man.

The pattern of blood flow in the large extra parenchymal pulmonary veins is pulsatile in both dog and man. This pulsatility is dominated by the changes in left atrial pressure taking place throughout the cardiac cycle. No pulsatile component of low in the large pulmonary veins could be attributed to forward transmission of a flow pulse conducted from the lung capillaries. The findings suggest that there must be a region of considerable compliance in the pulmonary venous system which can absorb pulsations from the lung capillaries and eliminate their transmission to the left atrium.

Animals↗
PubMed1982

Intra-SA-nodal pacemaker shift: indirect evaluation in the open chest dog.

Thirteen open chest dogs with normal sinus node function were studied by premature stimulations with a constant relative prematurity--50% of the preceding sinus cycle length. These premature beats were induced in the lower part of the crista terminalis of the right atrium and to the roof of the left atrium. Significant linear correlations were found between the return cycle (A2A3) and the spontaneous cycle (A1A1) lengths, with a slope of +0.75 in the right atrium, +1.36 in the left atrium. The evaluation of sinus node function is disturbed by pacemaker shifts, both spontaneous and induced. Sinus node organisation may be assessed by stimulating standardised sites, by measuring intra-atrial conduction time, and by comparing A2A3 with A1A1 at constant relative prematurity during significant variations in A1A1 obtained with changes in vago-sympathetic tone.

Animals↗
PubMed1989

Relationship between urinary kallikrein excretion and plasma atrial natriuretic factor in essential hypertensives.

Relationships between renal kallikrein and plasma atrial natriuretic factor were investigated by measuring urinary kallikrein excretion (by spectrophotometric assay) and plasma atrial natriuretic factor (by radio-immunoassay after extraction from plasma) in 84 normal subjects and in 104 essential hypertensives with a normal renal function. The atrial natriuretic factor was significantly higher in the essential hypertensives than in the normal subjects (38.5 +/- 1.3 versus 29.0 +/- 1.3 pg/ml, P less than 0.01), whereas urinary kallikrein excretion was significantly lower in the hypertensives than in the normal subjects (11.1 +/- 0.9 versus 15.3 +/- 0.6 nkat/24 h, P less than 0.01). Taking the 95% confidence limits of urinary kallikrein excretion in the normal subjects (from 4.5 to 29.9 nkat/24 h), we divided our essential hypertensives into two subgroups, patients with a normal kallikrein excretion (n = 80; mean urinary kallikrein excretion 13.8 +/- 0.8 nkat/24 h) and patients with a low kallikrein excretion (n = 24; mean urinary kallikrein excretion 2.3 +/- 0.3 nkat/24 h) The patients with a normal kallikrein excretion had a mean plasma atrial natriuretic factor value of 31.9 +/- 1.2 pg/ml, which was similar to that found in normal subjects. In contrast, the mean plasma level of atrial natriuretic factor in the patients with a low kallikrein excretion (50.7 +/- 2.2 pg/ml) was significantly higher than that measured in the patients with a normal kallikrein excretion and in the normal subjects (P less than 0.01 versus patients with normal kallikrein excretion and normal subjects, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies↗
PubMed1998

Heart rate behavior in children with atrial septal defect.

The aim of this study was to assess heart rate variability, a noninvasive parameter for studying the neurohumoral control of heart rate, in children with atrial septal defect. We examined five time-domain and three frequency-domain indices of heart rate variability determined from 24-hour Holter recordings in 20 children, aged 3-14 years, with secundum atrial septal defect who were about to undergo operation. The measures were compared to normal ranges and to the hemodynamic data of the preoperative cardiac catheterization. Most indices of heart rate variability were moderately depressed in children with atrial septal defect. Our data revealed negative correlations between indices and the mean right atrial pressure and the enddiastolic right ventricular pressure, respectively. The study demonstrates the importance of the right ventricular filling pressures for the autonomic control of the heart in children with atrial septal defect.

Adolescent↗
PubMed2003

Atrial electrophysiology and mechanisms of atrial fibrillation.

Atrial fibrillation is the most common cardiac arrhythmia in clinical practice, and its management remains challenging. A solid understanding of the scientific basis for atrial fibrillation therapy requires insight into the mechanisms underlying the arrhythmia, about which an enormous amount has been learned over the past 10 years. The basic information presently available about atrial fibrillation mechanisms is reviewed. The particular properties of normal atrial electrophysiology are discussed, including salient ionic determinants of the atrial action potential and key anatomic features. Reviewed are three crucial arrhythmia mechanisms long held to be involved in atrial fibrillation: 1) rapid ectopic activity, 2) single-circuit reentry with fibrillatory conduction, and 3) multiple-circuit reentry. The determinants of each and the evidence for their involvement in clinical and/or experimental atrial fibrillation are noted. The physiological consequences, various contributing mechanisms, and clinical implications of the role of atrial-tachycardia remodeling are analyzed. Atrial-tachycardia remodeling links the potential mechanisms of atrial fibrillation, since atrial fibrillation beginning by any mechanism is likely to cause tachycardia-remodeling and thus promote the maintenance of atrial fibrillation by multiple-circuit reentry. Atrial structural remodeling is discussed as a paradigm of atrial fibrillation in which the classic features required for reentry (reduced refractory period and reentrant wavelength) may be lacking. Finally, the importance of recent insights into potential genetic determinants of atrial fibrillation is reviewed. The classic understanding of atrial fibrillation pathophysiology saw the different possible mechanisms as being alternative and opposing hypotheses. We now consider the multiple potential mechanisms as contributing to the pathophysiology of the arrhythmia to a different extent in different clinical settings and interacting with each other in a dynamic way at various stages of the natural history in many patients. It is hoped that this improved mechanistic understanding will lead to the development of improved therapeutic options.

Action Potentials↗
PubMed1987

Atrial natriuretic polypeptide during exercise in healthy man.

The plasma concentration of atrial natriuretic polypeptide was measured in eight healthy men during two grades of exercise performed in the supine position on a bicycle ergometer. The plasma concentration of atrial natriuretic polypeptide slightly increased during the first exercise test with 20% of the maximal oxygen uptake and it approximately doubled during the second exercise with 40% of the maximal oxygen uptake (from 15.5 +/- 5.5 (mean +/- SD) pmol/l to 31.8 +/- 10.7 pmol/l). The increase in the plasma level of atrial natriuretic polypeptide in the second exercise was significantly greater than that in the first one. The plasma norepinephrine level and plasma renin activity showed significant increases during the second exercise test. Heart rate and systolic blood pressure also increased in response to the graded exercise. The increase in the plasma concentration of atrial natriuretic polypeptide during exercise was significantly correlated with the increase in heart rate, systolic blood pressure, and the plasma norepinephrine concentration (r = 0.75, r = 0.71 and r = 0.51, respectively). These results indicate that the plasma concentration of atrial natriuretic polypeptide increases in response to the intensity of a workload, and suggest that exercise is a useful test to evaluate the releasing function of atrial natriuretic polypeptide in the heart.

Adult↗
PubMed1997

[Atrial septum defect and open foramen ovale. Diagnosis, clinical aspects and therapy using a catheter technique].

The purpose of this report is to describe the pathophysiology and clinical symptoms of atrial septal defects with emphasis on right ventricular failure and the risk of paradoxical embolism in the setting of a patent foramen ovale. The diagnosis of both the atrial septal defects and the patent foramen ovale, usually is made by echocardiography. Percutaneous transcatheter occlusion of an atrial septal defect and a patent foramen ovale has gained interest for some years as a treatment alternative to surgical closure. Preliminary results of different devices have been encouraging and the method appears to be a viable alternative to surgical closure.

Atrial Function, Right↗
PubMed1988

Atrial automatic ectopic tachycardia due to an atrial tumor.

A dilated cardiomyopathy picture has been produced by rapid atrial and ventricular rates sustained for a long period of time in some patients. The ventricular tachycardias have in some instances been associated with ventricular tumors as the cause of the tachycardia. Once the tumor is removed, the tachycardia stops and the heart function improves. Atrial ectopic tachycardias also produce a similar picture, but have not been associated with atrial tumors. Such a case is presented with an atrial rhabdomyoma producing atrial ectopic tachycardia and a dilated, poorly contracting myocardium. The tumor was resected and the tachycardia was immediately abolished. Cardiac function quickly returned to normal.

Cardiomyopathy, Dilated↗
PubMed1988

[Function of the right ventricle in interauricular communication in adults].

This study was designed prospectively to analyze the influence of age and operation on right ventricular function in atrial septal defect; 17 patients were studied by means of radionuclide studies performed immediately before and approximately 6 months (5,8 +/- 2,3) after surgery. The pulmonary/systemic flow ratio (Qp/Qs) was determined by first pass technique, and right ventricular ejection fraction and peak filling rate were determined by equilibrium ventriculography. In addition, all patients had preoperative catheterization. According to age, patients were divided in group I (less than 35 years) and group II (greater than or equal to 35 years). Preoperatively, patients in group I, in comparison to group II, had better ejection fraction (48 +/- 8 vs 36 +/- 7; p less than 0.01), and better peak filling rate (3.7 +/- 0.9 vs 2.6 +/- 0.7; p less than 0.01), while Qp/Qs were not significantly different (2.5 +/- 0.8 vs 3.0 +/- 1.6) and pulmonary vascular resistances were less elevated (69 +/- 32 vs157 +/- 95 dynes/sec/cm-5; p less than 0.01). After surgery, right ventricular function did not significatively change in relation to preoperative data in both groups (ejection fraction: 44 +/- 13 and 34 +/- 5, respectively; peak filling rate: 3.3 +/- 1.4 and 2.1 +/- 0.6). We conclude that in atrial septal defect indexes of systolic and diastolic right ventricular function deteriorate with age, these changes being associated with a slight increase in pulmonary vascular resistance without changes of Qp/Qs; right ventricular dysfunction does not tend to improve postoperatively.

Adolescent↗
PubMed1993

Right-to-left interatrial shunt in rats with progressive pulmonary hypertension.

A right-to-left interatrial shunt may prolong survival in patients with pulmonary hypertension presumably because of decompression of the right side of the heart. To test this hypothesis, 74 rats with monocrotaline-induced pulmonary hypertension were followed up weekly with cardiopulmonary exercise testing with a metabolic treadmill system for exercise tolerance, heart rate, oxygen uptake, carbon dioxide production, and survival until subsequent or induced death 8 weeks after monocrotaline treatment. In rats with an interatrial shunt, oxygen uptake and carbon dioxide production were higher and survival was better (n = 22, 27%) than those in rats without a shunt (n = 52, 0%; p < 0.05). For the prospective assessment of the effects of a reversed shunt, 24 other rats underwent a left superior vena cava-to-left atrial appendage anastomosis as a functional interatrial shunt (atrial septal defect group) 4 weeks after monocrotaline treatment when severe pulmonary hypertension had developed and were compared with an additional 25 rats receiving a sham operation. Both groups had exercise capacity depressed to the resting levels by 2 weeks after operation. Although transcutaneous oxygen levels decreased in response to exercise in the atrial septal defect group, uptake and carbon dioxide production stayed higher than those in the sham operation group with significantly better survival 4 weeks after operation (atrial septal defect 30% versus sham operation, 0%; p < 0.05), at which time a reversed shunt was determined with systemic embolization of intravenously infused microspheres. A right-to-left interatrial shunt, anatomic or functional, preserved basal metabolism and prolonged survival in rats with progressive pulmonary hypertension.

Animals↗
PubMed1991

Effect of a ring-deleted atrial natriuretic factor analogue on ovine fetal renal and cardiovascular function.

The proposed actions of atrial natriuretic factor (ANF) are mediated through specific plasma membrane (R1) receptors coupled to guanylate cyclase. A second receptor, R2, has been characterized by its ability to bind to an acyclic, truncated ANF analog (C-ANF4-23). The ANF-R2 receptor has not been identified in the fetus. Our study was conducted to determine the effects of C-ANF on fetal renal and cardiovascular function and plasma ANF clearance rates. Chronically catheterized ovine fetuses (n = 6) at 111 to 117 d gestation (term 145 d) received a C-ANF infusion (1 microgram/min/kg) for 30 min followed by a combined infusion of C-ANF and ANF (C-ANF, 1 microgram/min/kg; ANF, 100 ng/min/kg) for an additional 30 min. C-ANF infusion significantly increased (mean +/- SEM) plasma ANF concentration (437 +/- 45 to 1067 +/- 297 pg/mL), urinary flow rate (0.26 +/- 0.04 to 0.38 +/- 0.07 mL/min/kg), sodium excretion (12.9 +/- 3.5 to 21.7 +/- 6.1 mumol/min/kg), and osmolar clearance (0.14 +/- 0.02 to 0.21 +/- 0.04 mL/min/kg) (p less than 0.05). The combined C-ANF/ANF infusion further increased plasma ANF concentration to 2394 +/- 532 pg/mL and resulted in significant increases in urinary flow rate, sodium excretion, osmolar clearance, GFR, and free water clearance compared with C-ANF infusion alone (p less than 0.05). These renal responses, however, were not significantly different from the responses to ANF infusion alone (100 ng/min/kg).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗