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At least 1,261 records · Page 70Linked to original sources
PubMed1984

Effects of synthetic atrial natriuretic factor on renal function and renin release.

Studies were performed in anesthetized dogs (n = 5) to determine the effects of synthetic atrial natriuretic factor on renal function and renin release. Intrarenal infusion of synthetic atrial natriuretic factor (ANF) (0.3 microgram X kg-1 X min-1) resulted in a transient increase in renal blood flow (126 +/- 8 to 148 +/- 11 ml/min). The duration of this transient vasodilation was 3.1 +/- 0.4 min. Continued infusion was followed by a slight decrease in renal blood flow (126 +/- 8 to 117 +/- 8 ml/min) and an increase in glomerular filtration rate (23.1 +/- 3.5 to 30.7 +/- 1.9 ml/min), with filtration fraction thus being increased (0.19 +/- 0.04 to 0.27 +/- 0.03). These hemodynamic alterations were associated with increases in fractional sodium excretion (0.6 +/- 0.2 to 5.8 +/- 0.8%), fractional potassium excretion (30.8 +/- 9.4 to 56.3 +/- 7.4%), fractional lithium excretion (32.2 +/- 7.1 to 60.3 +/- 5.7%), and fractional phosphate excretion (8.7 +/- 3.5 to 41.6 +/- 11.7%). Intrarenal infusion of synthetic ANF markedly suppressed renin secretion rate (295.5 +/- 84.6 to 17.2 +/- 10.6 ng/min) despite a slight reduction in arterial pressure (123 +/- 9 to 118 +/- 9 mmHg). Our studies demonstrate that synthetic ANF results in a marked natriuretic response that is in part mediated by an increase in glomerular filtration rate. The increase in fractional lithium and phosphate excretion suggests that this factor may also have an action on proximal tubule reabsorption. Further, these studies demonstrate that synthetic ANF markedly inhibits renin secretion.

Animals↗
PubMed1990

[Effect of cardioversion of atrial fibrillation on left ventricular function in dilated cardiomyopathy. A multicenter study].

A group of 73 patients with idiopathic dilated cardiomyopathy were followed up for an average of 22 +/- 7 months to assess the medium term evolution of echocardiographic parameters of left ventricular function and, in particular, the consequences of cardioversion of atrial fibrillation. Seventy nine per cent of patients presented with cardiac failure. Left bundle branch block was observed in 20% and ventricular arrhythmias were frequent in 31%, complex in 62% with episodes of non-sustained ventricular tachycardia in 10% of cases. Left ventricular dilatation was greater in patients with complete left bundle branch block (p less than 0.003). Atrial fibrillation was present in 14 patients (19%) who were generally older than the rest of the study population (p less than 0.02) and was associated with less severe left ventricular dysfunction (p less than 0.01). Return to sinus rhythm was obtained in 9 patients. Echocardiographic data was obtained in 64 patients after an average of 6.2 +/- 1.7 months. Left ventricular function improved during the follow-up period and returned to normal in 12% of cases. Reduction of atrial fibrillation to sinus rhythm was the only predictive factor of normalisation of left ventricular function (p less than 0.02). The changes in left ventricular end diastolic dimension and fractional shortening was less marked in the group of 56 patients in sinus rhythm or chronic atrial fibrillation (normalisation of left ventricular function in 8% of cases) than in the group of 8 patients in which atrial fibrillation was converted to sinus rhythm (normalisation of left ventricular function in 50% of cases).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Left atrial and left ventricular diastolic function during acute myocardial ischaemia.

OBJECTIVE: To study indices of diastolic left ventricular function during the first few seconds of myocardial ischaemia. DESIGN: Isovolumic and total relaxation times and left atrial and left ventricular dP/dt were identified from high fidelity (micromanometer) pressure recordings in the left ventricle and left atrium during percutaneous transluminal angioplasty of the left anterior descending coronary artery. PATIENTS: 20 patients with isolated disease of the left anterior descending artery and normal left ventricular function. RESULTS: The isovolumic relaxation time lengthened during the first seven to nine seconds of ischaemia; then it shortened by an average of 15% up to the twentieth second, initially as a result of increased left atrial contractility and subsequently because of impaired ventricular relaxation. Ventricular ischaemia resulted in impaired left ventricular diastolic compliance, as shown by an increase in the total relaxation time, before there was evidence of systolic impairment. Minimum dP/dt decreased progressively (by -37% at the twentieth second of ischaemia), whereas maximum dP/dt fell only after 20 seconds of ischaemia (by -11%). CONCLUSIONS: Relaxation and filling of the left ventricle (indices of diastolic function) are more sensitive to myocardial ischaemia than myocardial contractility and systolic function. Left atrial contractility increases during left ventricular ischaemia.

Adult↗
PubMed1992

[Changes in the concentration of plasma cardionatrin and morphological changes of atrial cardiocytes after severe burn].

The purpose of this experiment is to investigate the changes in plasma concentration cardionatrin of and morphological changes in atrial cardiocytes in rats after severe burn by means of radioimmunoassay, immunocytochemistry, electron microscopy and morphometry. The results showed that: (1) At 1, 2 h postburn the plasma cardionatrin concentrations were significantly increased, at 6-48 h significantly decreased and at 72, 168 h returned to normal. (2) The changes in plasma cardionatrin concentration were related to the alterations of secretory function in atrial cardiocytes. (3) The pathological changes in atrial cardiocytes were characterized by appearing early. The pathological changes and alterations of secretory function of atrial cardiocytes ran a dynamic course, which could be roughly divided into three phases, the phase of stress, the phase of secretory inhibition and injury, and the phase of recovery. (4) It might be one of the forms of atrial cardiocytes secreting cardionatrin that the atrial specific granules with intact limiting membrane were excreted from the defect of plasmalemma.

Animals↗
PubMed1990

Effect of atrial natriuretic factor on platelet function in whole blood ex-vivo in man.

Atrial natriuretic factor (ANF) binding sites have been shown to be present on human platelet membranes. We investigated the effect of an infusion of ANF 5 pmol.kg-1.min-1 on platelet aggregation in whole blood ex-vivo in 8 normal volunteers. Spontaneous platelet aggregation, collagen (0.6-2 micrograms.m.-1)-induced or ADP (0.5-2.0 microM)-induced aggregation was not affected by ANF. Plasma aldosterone was however significantly attenuated by ANF. These results show that a pharmacological dose of ANF does not affect platelet aggregation in man. These results suggest that the high plasma levels of ANF normally achieved in chronic heart failure or acute myocardial infarction are unlikely to contribute to the platelet hyperractivity, often observed in these conditions.

Adenosine Diphosphate↗
PubMed1985

[The function of retrograde (ventricular-atrial) conduction in Wolff-Parkinson-White syndrome patients].

Functional characteristics of the retrograde conduction in the WPW syndrome were studied in 68 patients by means of electrophysiological examination of the heart. The retrograde conduction via the Kent bundle was characterized by constant time of the atrioventricular conduction. The latent WPW syndrome with the accessory pathway blocked in the anterograde direction and functioning in the retrograde direction only was detected in 22 cases. A possible successive relationship of the classical and latent WPW syndrome was shown. Higher functional possibilities of the accessory pathway for the retrograde conduction were revealed in comparison with the anterograde conduction.

Adolescent↗
PubMed1989

Opposite effects of enalapril and nitrendipine on natriuretic response to atrial natriuretic factor. Renal function evaluated with clearance studies in humans.

In clearance studies, we analyzed the effect of Ca2+ entry blockade with nitrendipine treatment (20 mg b.i.d. for 4 days) and of converting enzyme inhibition with enalapril treatment (20 mg b.i.d. for 4 days) on renal response to atrial natriuretic factor (ANF) (25 micrograms bolus followed by an infusion of 0.03 microgram/kg/min for 90 minutes) in six healthy volunteers who were taking 300 mmol sodium daily. In a control study ANF was administered without Ca2+ entry blockade or converting enzyme inhibition. Natriuresis rose from 239 +/- 38 to 605 +/- 137 mumol/min in the control study (p less than 0.05), from 330 +/- 53 to 943 +/- 152 mumol/min with Ca2+ entry blockade (p less than 0.05), and from 236 +/- 22 to 344 +/- 39 mumol/min with converting enzyme inhibition (NS). ANF induced a rise in maximal free water clearance, inulin clearance, and in the excretion of multiple electrolytes except potassium. Fractional lithium reabsorption fell. In general, these effects were stronger during Ca2+ entry blockade and blunted during converting enzyme inhibition. p-Aminohippurate clearance tended to decrease during the control study (NS), remained constant during Ca2+ entry blockade, and decreased significantly when ANF was infused during converting enzyme inhibition (p less than 0.05 vs. control and vs. Ca2+ entry blockade study). Blood pressure was lowered by Ca2+ entry blockade and, to a somewhat greater extent, by converting enzyme inhibition, but ANF administration induced no additional fall except for a short-term drop during Ca2+ entry blockade.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Atrial activity and its effects].

The initiation of cardiac impulse is located in the sinus node, in the upper anterior part of the right atrium. The importance of the atrium is not only linked to the regulation of heart rate, but also to its haemodynamic function. Indeed, atrial depolarization leads to atrial contraction which can be responsible for up to 30% of cardiac output by way of ventricular filling. Supraventricular arrhythmias are related to one of the following mechanisms: abnormal automaticity, triggered activity, and reentry. Most of supraventricular tachycardias are due to a reentrant phenomenon (intranodal reentrant tachycardia, orthodromic circusmovement tachycardia, atrial flutter and atrial fibrillation). At the onset of a supraventricular tachycardia, the loss of efficacious atrial contraction as well as the increased heart rate may abruptly decrease ventricular filling. As a consequence, stroke volume is reduced, leading to a decrease in cardiac output and in arterial blood pressure, explaining that the patient may experience syncope. Usually, blood pressure reduction resumes within 30 seconds after activation of the autonomic adrenergic nervous system. In case of an underlying heart disease, the supraventricular tachycardia may lead to acute cardiac failure. When reentry is concerned, the tachycardia is going around a specific circuit. The existence of such a circuit in most of supraventricular tachycardias has led to the development of ablation therapy, the goal of which is to destroy a critical portion of the circuit hence making the recurrence of reentrant tachycardia impossible.

Arrhythmias, Cardiac↗
PubMed1996

Effect of an irregular ventricular rhythm on cardiac output.

Impairment of cardiac function in atrial fibrillation has been attributed to loss of atrial contraction and to a rapid ventricular rate. The results of this study suggest that irregularity of the ventricular rhythm, independent of the ventricular rate, may also contribute to impairment of cardiac function during atrial fibrillation.

Atrial Fibrillation↗
PubMed1975

Sinoatrial block. Autonomic influences and clinical assessment.

Seventeen patient with sinoatrial block and 16 healthy volunteers were investigated with recently developed autonomic tests of atrial pacemaker function. Only one patients was found to be entirely normal in comparison with normal subjects, while another patients had supernormal responses. Fifteen patients had reduced responses relative to the controls implying impaired atrial pacemaker function or sinoatrial disease. It is suggested that while in some cases sinoatrial block may be of physiological origin, it is more often due to sinoatrial disease. The latter group are liable to Adams-Stokes syncope and may have additional atricventricular conduction abnormalities. The possible mechanisms and treatment of sinoatrial block are discussed relative to the autonomic and pacemaker function abnormalities described.

Adams-Stokes Syndrome↗
PubMed2005

Recovery of cardiac function after ablation of atrial tachycardia arising from the tricuspid annulus.

Tachycardia-induced cardiomyopathy is a reversible form of heart failure. An early diagnosis and an effective cure of the underlying tachycardia are crucial for a favorable outcome. Different kinds of atrial and ventricular arrhythmias may induce tachycardiomyopathy. Focal atrial tachycardia may be easily suppressed by means of transcatheter ablation. Relationships between focal atrial tachycardia and tachycardiomyopathy have not been deeply analyzed. In the present paper we report a case of a 76-year-old man with tachycardia-induced cardiomyopathy caused by recurrences of focal atrial tachycardia arising from the tricuspid annulus. The arrhythmia was successfully treated with transcatheter ablation. In the follow-up no recurrences of the arrhythmia occurred and a significant improvement in myocardial function was observed.

Aged↗
PubMed1995

[The maze operation: surgical therapy of chronic atrial fibrillation].

The maze operation is a newly developed surgical procedure for patients with chronic atrial fibrillation. Between may 1993 and october 1994, 11 patients underwent mitral valve surgery combined with the maze procedure, 10 for chronic, medically refractory, symptomatic atrial fibrillation and 1 for intermittent, symptomatic atrial flutter. In one patient, a double aorto-coronary venous bypass was added. The operative mortality was 9%: one patient died on the 7th postoperative day from a perioperative cerebrovascular accident. Postoperatively, electrophysiological and stress testing as well as transthoracic or transesophageal echocardiography (TTE; TEE) were performed. All patients were in sinus rhythm. Left and right atrial contractions were analyzed by TTE/TEE and the atrial transport function was documented in each patient. The postoperative exercise stress test revealed slight sinus-node incompetence. After a mean follow-up time of 10.4 +/- 5.4 months (1 to 16 months) all surviving patients are free from atrial fibrillation or flutter and without need for medication. The maze operation, which we performed for the first time in connection with mitral valve surgery, is a successful treatment for chronic, medically refractory atrial fibrillation and intermittent, symptomatic atrial flutter. This procedure provides a sinus rhythm with atrioventricular synchrony, restores the atrial transport function and obviates the need for antiarrhythmic drugs. Long-term anticoagulation appears unnecessary.

Adult↗
PubMed1992

[Functional heterogeneity of the atrial myocardium in patients with congenital and acquired heart defects].

In experiments on atrium trabeculae the heterogeneity of myocardium contractile activity in patients operated on for inborn or acquired heart defects was studied. Contractile activity was assessed in isometric regime of muscle drugs work. The degree of functional heterogeneity was reported to differ in myocardium biopsies from patients with inborn or acquired heart defects. The difference was expressed in susceptibility to stimulating action or electrical impulses and in the degree of the change of myocardium contractile activity. The study of human myocardium functional heterogeneity is likely to present a new approach to increase efficacy of the work of pathologically changed heart muscle.

Biopsy↗
PubMed1980

[Influence of left atrial pressure on left ventricular function after extracorporeal circulation (author's transl)].

In 10 patients with coronary heart disease, in 9 with advanced mitral and in 11 with aortic valve disease left ventricular function curves were constructed by volume loading immediately after cardiopulmonary bypass. After aortocoronary bypass surgery an approximately linear correlation between both cardiac index and stroke volume index and left ventricular filling pressure was demonstrated. After aortic and mitral valve replacement increase in left ventricular filling pressure above 15 mm Hg failed to result in significant increase in CI and SVI. Apparently, volume loading has limited effects in regulating left ventricular function in advanced aortic and mitral valve disease.

Atrial Function↗
PubMed1993

The interaction between atrial natriuretic peptide and cardiac parasympathetic function.

We have demonstrated previously that atrial natriuretic peptide (ANP) inhibits hypotension-induced reflex tachycardia via a parasympathetic mechanism. The present study further defines that parasympathetic mechanism. We tested the hypothesis that ANP, during vagus nerve stimulation, acts as a physiological antagonist to interfere with alpha 1-adrenoceptor modulation of efferent cardiac vagal action. Sprague Dawley rats were divided into five groups, each group receiving a different infusion. Infusates included one of vehicle (Ringer's solution; RS), an alpha 1-adrenoceptor agonist (phenylephrine; PE), a combination of agonist and either a known alpha 1-adrenoceptor antagonist (prazosin; PE+PRZ) or the putative physiologic antagonist, ANP (PE+ANP). The fifth group received all three drugs, PE+PRZ+ANP. Under Inactin anesthesia (100 mg/kg i.p.), efferent autonomic input to the heart was surgically interrupted. Animals were also adrenalectomized to limit the effects of circulating catecholamines. We then monitored each group for the change in heart rate (delta HR) in response to efferent vagus nerve stimulation at various frequencies (2 Hz, 5 Hz, 10 Hz). Infusion of PE significantly (P < 0.01 by ANOVA) attenuated the magnitude of delta HR when compared to the RS group. This attenuation of vagally-induced bradycardia was eliminated by the addition of the alpha 1-adrenoceptor antagonist, prazosin (PE+PRZ group). The PE+ANP group responded with results similar to those of the PE+PRZ group. There was no difference between delta HR responses of the PE+PRZ+ANP group and the PE+PRZ group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1987

Left ventricular geometry and function in adults with Ebstein's anomaly of the tricuspid valve.

We postulated that the abnormal shape, size, and function of the right heart and adjoining ventricular septum in adults with Ebstein's anomaly of the tricuspid valve might in turn alter the shape and function of the left ventricle. Seven adult patients with uncomplicated Ebstein's anomaly were studied. Left ventricular geometry was determined by two-dimensional echocardiography. Left ventricular function was assessed by treadmill exercise and radionuclide angiography at rest and with exercise. Paradoxic ventricular septal motion was consistently present. Left ventricular eccentricity (ratio of two minor axes in the short-axis view) was uniformly abnormal, averaging 1.35 +/- 0.23 (normal = 1.02 +/- 0.05). The ratio of right to left ventricular cavity size averaged 1.70 +/- 0.44 (normal 0.65 +/- 0.30), and tricuspid valve displacement into the right ventricular cavity averaged 52% (normal 8%). Functional right atrial size averaged 27.6 +/- 5.2 cm2 (normal right atrial area = 13.1 +/- 2.2 cm2). Resting left ventricular ejection fractions were below 50% in all but two patients. In response to Bruce protocol exercise stress, there were consistently appropriate increments in heart rate, blood pressure, and peak double product and, with one exception, radionuclide left ventricular ejection fraction. There were significant correlations between tricuspid valve displacement and functional right atrial size versus resting left ventricular ejection fraction and left ventricular eccentricity. These data support the hypothesis that derangements in right heart morphology and function in Ebstein's anomaly contribute to significant alterations in left ventricular geometry, but the geometric alterations are associated with tangible but less significant changes in left ventricular systolic function.

Adolescent↗