[Atrial contribution to ventricular function in patients with pacemakers. Polygraphic study of 40 patients].
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Cardiac Pacing, Artificial↗
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[Assessment of left atrial and mitral valve functions by means of esophageal atriography].
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Blood Pressure↗
Reverse remodeling of sinus node function after catheter ablation of atrial fibrillation in patients with prolonged sinus pauses.
BACKGROUND: Symptomatic prolonged sinus pauses on termination of atrial fibrillation (AF) are an indication for pacemaker implantation. We evaluated sinus node function and clinical outcome in patients with prolonged sinus pauses on termination of arrhythmia who underwent ablation of paroxysmal AF. METHODS AND RESULTS: Twenty patients with paroxysmal AF and prolonged sinus pauses (> or =3 seconds) on termination of AF underwent ablation between May 1995 and November 2002. Patients with sinus pauses independent of episodes of AF were excluded from the analysis. The procedure included pulmonary vein and linear atrial ablation. After ablation, sinus node function was assessed during the first week and at 1, 3, and 6 months, by 24-hour ambulatory monitoring to determine the mean heart rate and heart rate range, and by exercise testing to determine the maximal heart rate. Corrected sinus node recovery time was determined at the completion of ablation and at 24.0+/-11.3 months at 600 and 400 ms. After AF ablation, there was a significant improvement of sinus node function, with an increase in the mean heart rate (P=0.001), maximal heart rate (P<0.0001), and heart rate range (P<0.0001). The corrected sinus node recovery time decreased in all patients evaluated at 600 ms (P=0.016) and 400 ms (P=0.019). At 26.0+/-17.6 months, 18 patients (85%) had no recurrence of AF (in the absence of medication), with no symptoms attributable to bradycardia or sinus pauses on ambulatory monitoring. Two patients had infrequent episodes of AF, 1 requiring pacemaker implantation. CONCLUSIONS: Prolonged sinus pauses after paroxysms of AF may result from depression of sinus node function that can be eliminated by curative ablation of AF. This is accompanied by improvement in parameters of sinus node function, suggesting reverse remodeling of the sinus node.
Atrial Fibrillation↗
Atrial natriuretic factor in cirrhosis: relationship to renal function and hemodynamic changes.
Plasma atrial natriuretic factor concentrations and different hemodynamic parameters, including the evaluation of femoral arteriovenous shunting by measuring the arteriovenous difference of oxygen content (Ca-vO2), were determined in eight healthy subjects and 24 patients with cirrhosis without renal failure (group I: seven patients without ascites, group II: nine patients with ascites and UNaV > 10 mEq/24 h and group III: eight patients with ascites and UNaV < or = 10 mEq/24 h). Atrial natriuretic factor was 34 +/- 4.7 pg/ml in the control group and 44.28 +/- 5.4, 67.89 +/- 8.8 and 84 +/- 10.8 pg/ml in groups I, II and III respectively (p < 0.001. group III vs. I and control and II vs. control). Atrial natriuretic factor directly correlated with cardiac index (p < 0.01), blood volume (p: 0.01), femoral blood flow (p < 0.01) and inversely with systemic and femoral vascular resistances (p < 0.02), Ca-vO2 (p < 0.01), serum albumin (r: -0.61; p < 0.01) and prothrombin index (r: -0.63; p < 0.02). These results indicate that plasma atrial natriuretic factor is increased in patients with cirrhosis, especially in those with advanced disease and marked renal sodium retention. This suggests that in cirrhosis, arteriolar vasodilation and peripheral arteriovenous shunting influence renal function while inducing a state of overflow at the central venous compartment leading to increased atrial natriuretic factor secretion. Increased production of this vasodilatory hormone may thus contribute to the hyperkinetic circulation of cirrhosis.
Atrial Natriuretic Factor↗
The effects of atrial natriuretic peptide on renal function and the renin-aldosterone system in anesthetized rabbits.
To determine the effects of alpha-human atrial natriuretic peptide (ANP) on renal function and the renin-aldosterone system in anesthetized rabbits, ANP (0.05 micrograms/kg/min) or 5% dextrose solution in vehicle control was infused intravenously. The infusion of ANP resulted in a significant decrease in mean arterial pressure with an increase in renal blood flow (RBF). ANP also produced significant increases in urine volume and urinary sodium excretion. ANP tended to increase glomerular filtration rate, filtered sodium load and net tubular reabsorption of sodium. However, there were no significant differences in these parameters compared with control group. Fractional sodium excretion was increased significantly by ANP. Plasma renin activity (PRA) was suppressed only at 30 min after the infusion of ANP, while a significant fall in plasma aldosterone concentration (PAC) lasted even in the recovery period. These results indicate that ANP produces a diuresis and natriuresis through the increased RBF in anesthetized rabbits. It is also suggested that ANP suppresses PAC independent of the inhibition of PRA.
Aldosterone↗
Effect of posture on plasma atrial natriuretic hormone and renal function during salt loading in patients with and without postural (idiopathic) edema.
The effect of posture on plasma atrial natriuretic hormone (ANH) and renal function was studied in subjects with idiopathic edema. Sixty-five subjects with edema but with no clinical evidence for cardiac, renal, or pulmonary diseases were studied after they had been off all medication for 1 week or more. They had nothing by mouth after midnight and were admitted to the Clinical Research Center at 0800 h. They voided, were weighed, and had their blood pressure and pulse measured in the recumbent and upright positions. A needle was inserted, and subjects were recumbent for 0.5 h, after which blood was drawn for measurement of plasma ANH, serum sodium, potassium, and (in 35 subjects) creatinine. They were then given 150 mL 0.14% sodium chloride solution to drink every 0.5 h for the next 6 h. Urine was collected every 0.5 h for measurement of sodium, potassium, and creatinine. After 4 h of recumbency repeat blood samples were drawn, subjects ambulated for 2 h, after which final repeat blood samples were drawn. Subjects were considered to have postural edema if their upright urinary sodium/previous 2-h urinary sodium was less than 33%, and to have a normal response if it was 33% or more. The clinical characteristics of the 34 patients with postural edema and 31 patients with a normal response were similar. Plasma ANH levels (initial, after oral saline, and after standing) were similar in the two groups, and there was no relationship between changes in ANH and urinary sodium with standing. In conclusion, under conditions of mild oral sodium chloride loading, changes in plasma ANH do not cause the abnormal sodium retention found in patients with postural edema.
Adult↗
[2D and Doppler echocardiography after atrial switch operation for transposition of great arteries; a review].
Introduction of the atrial baffle procedure (Mustard, Senning) more than 30 years ago has dramatically improved the prognosis of patients with transposition of the great arteries. However, a range of late complications can occur even in clinically asymptomatic patients including: superior and inferior limb obstruction, pulmonary venous obstruction, residual baffle-leakage, left ventricular outflow tract obstruction, tricuspid valve regurgitation, right ventricular dysfunction and postoperative dysrhythmia. As an increasing number of patients has reached adulthood an accurate noninvasive technique is needed for routine follow-up studies. In most patients transthoracic two-dimensional (2D) and Doppler echocardiography allows a complete investigation of postoperative hemodynamic abnormalities -- in particular assessment of atrial baffle function. In adult patients with restricted echo-windows transoesophageal echocardiography may provide a more detailed assessment of atrial baffle morphology and function; TEE seems to be superior compared to angiography and magnetic resonance imaging. Furthermore TEE is a reliable guiding and monitoring technique during interventional cardiac catheterization procedures such as balloon dilatation or stent implantation and allows further surveillance. Even if compared to other noninvasive diagnostic procedures, 2D and Doppler echocardiography (transthoracic/transoesophageal) are still the most important and accurate diagnostic methods for routine investigation of the postoperative anatomy and potential late complications in patients who underwent an atrial baffle procedure.
Echocardiography↗
Comparison of the effects of atrial and ventricular stimulation on sinus node function in man.
Although sinus node function has been evaluated during premature atrial stimulation, no study of retrograde ventriculoatrial sinus node activation following premature ventricular stimuli has been reported. The purpose of this study was to investigate the production of compensatory and noncompensatory pauses by premature ventricular contractions through a comparison of the effects of atrial and ventricular stimulation on sinus node function. Eleven patients in sinus rhythm were studied with programmed introduction of premature atrial and ventricular stimuli outside the ventricular vulnerable period. The onset of sinus node reset, duration of return sinus cycle (A2-A3) during reset, and estimated sinoatrial conduction times were recorded. Sinus node function during premature ventricular stimulation was approximated by utilizing the interval between the last sinus beat and onset of retrograde atrial depolarization (A1-A2 interval). The return cycle length (A2-A3) during sinus reset compared at equal A1-A2 intervals was significantly less with ventriculoatrial conduction (1,145 +/- 52 msec. atrial vs. 1,076 +/- 52 msec ventriculoatrial; P less than 0.01 by paired t test) and the estimated sinoatrial conduction time was significantly less with ventriculoatrial conduction (71 +/- 7 msec. atrial vs. 25 +/- 7 msec. ventriculoatrial; P less than 0.01 by paired t test). Ventriculoatrial sinus reset occurred later in the sinus cycle than atrial reset in three of seven patients with sinus reset produced by both atrial and ventricular prematures. This study shows that the effects of ventriculoatrial conduction on sinus node function are significantly different from those of atrial stimulation alone. The return sinus cycle length during reset and estimated sinoatrial conduction time are significantly reduced with ventriculoatrial conduction. Although the zones of sinus reset with atrial and ventricular stimulation are approximately equal, ventriculoatrial depolarization may produce sinus reset later in the sinus cycle in some cases.
Adult↗
[Comparative study of endocavitary recording and the 24-hour electrocardiogram in the study of sinus function. Apropos of 174 cases].
We compared the results of electrophysiological investigations of sino-atrial node function in a series of 174 patients (including the sino-atrial conduction time (SACT) according to the method of Narula and Strauss, the corrected sino-atrial recovery time (CSART) and, in, 22 patients, the atropine test) with the results of 24 hour Holter monitoring. 73 patients presented a pathological Strauss curve, 47 had a prolonged SACT (Strauss' method) and 19 had a pathological CSART. Of the 22 bradycardic patients, the injection of atropine relieved the bradycardia in 45.5 per cent of cases. 19 patients showed signs of sino-atrial node dysfunction on the 24 hour Holter recording. Of the 35 patients with a surface electrocardiogram (ECG) suspicious of sino-atrial node dysfunction, 21 (60%) had a prolonged SACT and 13 (37.1%) had a pathological CSART: 15 of them (42.8%) showed major electrophysiological abnormalities and 19 (54.3%) had a positive Holter. In two-thirds of the cases of pure sino-atrial bradycardia, the results of electrophysiological and Holter investigations were normal; in 50 per cent of cases of sino-atrial block and/or pause on the surface ECG, major abnormalities were found on both electrophysiology and the Holter monitor. The SACT, estimated according to the method of Strauss, is discorsdant with the SACT estimated according to Narula's method in 46 p. cent of cases. It seems that Strauss' SACT was more sensitive in our study. In 102 cases (59.3%), the SACT and the CSART were concordant. In 10 cases, the SACT was normal while the CSART was pathological and in 42 cases, the SACT was pathological while the CSART was normal.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Muscarinic receptor subtypes: M1 and M2 biochemical and functional characterization.
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Animals↗
Left heart function during right heart pacing.
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Atrial Function, Left↗
The relationship between plasma levels of immunoreactive atrial natriuretic hormone and hemodynamic function in man.
To evaluate the relationship between plasma levels of immunoreactive atrial natriuretic hormone (IR-ANH) and different hemodynamic parameters in man, we studied 34 patients undergoing right heart catheterization. Plasma levels of IR-ANH in blood samples withdrawn from the femoral vein (n = 28), right ventricle (n = 27), and left ventricle (n = 17) were determined by radioimmunoassay. Right atrial pressure, pulmonary arterial wedge pressure, heart rate, and mean arterial pressure were found to be independent and significant predictors of IR-ANH plasma levels. The closest correlations were between right atrial pressure and either right ventricular IR-ANH levels (r = .78, p greater than .001) or femoral vein IR-ANH levels (r = .52, p less than .006). Five patients with isolated left ventricular failure had elevated IR-ANH levels out of proportion to their right atrial pressure levels. Pulmonary arterial wedge pressure also correlated with right ventricular IR-ANH levels (r = .46, p less than .002) and with femoral vein IR-ANH levels (r = .58, p less than .002). A single patient with isolated right heart failure had markedly elevated IR-ANH levels despite normal pulmonary arterial wedge pressure. Right ventricular levels were twice femoral vein levels and were closely correlated (181 +/- 40 vs 90 +/- 20 pmol/liter; r = .90, p less than .001). Right ventricular and left ventricular levels were almost identical (155 +/- 46 vs 146 +/- 43 pmol/liter; r = .99, p less than .001). Patients with volume overload states had elevated IR-ANH levels.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Beneficial effects of biatrial pacing on cardiac function in patients with bradycardia -- tachycardia syndrome.
BACKGROUND: Biatrial (BiA) pacing prevents atrial fibrillation. By an unknown mechanism. The purpose of this study was to use Doppler echocardiography to evaluate the hemodynamic effects during BiA pacing. METHODS AND RESULTS: The subjects were 7 patients with bradycardia - tachycardia syndrome with an implanted pacemaker. Atrial pacing sites were the right atrial appendage (RAA) and coronary sinus. P wave duration during BiA pacing (123 +/-16 ms) was significantly shorter than during either RAA pacing (167+/-19 ms, p<0.05) or sinus rhythm (148+/-12 ms, p<0.05). Doppler echocardiography revealed a greater cardiac output during BiA pacing than during RAA pacing (4.1+/-1.1 vs 3.5+/-0.7 L/min, p=0.042). The Doppler waveform of transmitral flow indicated that the left ventricular contraction interrupted the atrial filling wave during RAA pacing. The interval between the end of the atrial filling wave of transmitral flow and the mitral valvular closing sound was significantly increased by BiA pacing compared with RAA pacing (56+/-65 vs 40+/-57 ms, p=0.047). CONCLUSION: Cardiac hemodynamics were improved by BiA pacing and reduction of left atrial load may be one of the mechanisms.
Aged↗
Effects of prolonged infusions of atrial natriuretic peptide and isoproterenol on the mechanical and endocrine function of isolated atria.
We have measured the rate of release of atrial natriuretic peptide in response to stretch and to isoproterenol from superfused atria isolated from rats after chronic in vivo infusion of either atrial natriuretic peptide or isoproterenol. The infusion lasted seven days, using minipumps filled with: 1) saline; 2) synthetic atrial natriuretic peptide to release 3 micrograms/kg/h; 3) l-isoproterenol HCl to release 400 micrograms/kg/h. Infusion of isoproterenol caused hypertrophy of the left chambers of the heart, a decrease of atrial content of atrial peptide with increased plasma levels. Infusion of atrial natriuretic peptide resulted only in elevated plasma levels of the peptide. Atria from animals infused with atrial natriuretic peptide responded to stretch and to isoproterenol (10(-9) M) with a prompt and transient release of peptide. Atria from animals infused with isoproterenol showed a severe reduction in sensitivity to the inotropic and chronotropic action of the drug. Their basal release of atrial peptide was extremely reduced and they were unable to respond to stretch or to isoproterenol. These data indicate that high circulating levels of atrial natriuretic peptide do not influence the release of the peptide from the atria, while high levels of isoproterenol drastically reduce it. Beta adrenoceptor desensitization, atrial hypertrophy and decrease of stores of atrial peptide are likely to account for this phenomenon.
Animals↗
Effect of rate and rhythm control on left ventricular function and cardiac dimensions in patients with persistent atrial fibrillation: results from the RAte Control versus Electrical Cardioversion for Persistent Atrial Fibrillation (RACE) study.
OBJECTIVES: The purpose of this study was to evaluate left ventricular function and atrial and ventricular diameters in patients with persistent atrial fibrillation (AF) treated with rate or rhythm control. BACKGROUND: Restoration of sinus rhythm in patients with persistent AF may improve left ventricular function and reduce atrial dimensions. Adequate rate control in AF may preserve ventricular function. METHODS: In 335 patients included in the RAte Control versus Electrical Cardioversion for Persistent Atrial Fibrillation (RACE) study, echocardiography was performed at baseline and 1- and 2-year follow-up. Echocardiography was compared between patients randomized to rate control (n = 160) and rhythm control (n = 175). In the rhythm control group, echocardiography was compared between patients with AF versus sinus rhythm at study end. Multivariate analysis was performed to determine parameters related to improvement of left ventricular function and increase of atrial diameters. RESULTS: Fractional shortening improved significantly under rate and rhythm control (31 +/- 10% at baseline to 33 +/- 9% at 2 years, and from 30 +/- 10% to 34 +/- 9%; both P < .05, respectively). Under rate control, left and right atrial size increased significantly compared to baseline. Under rhythm control, only left atrial size increased. Multivariate analysis revealed that only sinus rhythm at study end was associated with an increase of fractional shortening. AF at study end, hypertension, and no use of angiotensin-converting enzyme inhibitors were independently associated with increase in atrial size. CONCLUSIONS: Routine rate control prevents deterioration of left ventricular function. Maintenance of sinus rhythm is associated with improvement of left ventricular function and reduction of atrial sizes.
Aged↗
Functional status in rate- versus rhythm-control strategies for atrial fibrillation: results of the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) Functional Status Substudy.
OBJECTIVES: The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) functional status substudy aimed to test the hypothesis that functional status is similar in rate-control and rhythm-control strategies. BACKGROUND: Randomized studies, including the AFFIRM study, have failed to demonstrate survival benefits between rate-control and rhythm-control strategies for atrial fibrillation (AF). However, AF may cause functional capacity or cognitive impairment that might justify maintenance of sinus rhythm. METHODS: Investigators of the AFFIRM study enrolled 4,060 patients with AF who required long-term therapy and who were 65 years of age or older or who had another risk factor for stroke or death. New York Heart Association functional class (NYHA-FC) and Canadian Cardiovascular Society Angina Classification were assessed at initial and each follow-up visit. From 22 randomly chosen functional status substudy sites, 245 participants underwent 6-min walk tests and Mini-Mental State Examination (MMSE) at initial, two-month, and yearly visits. Patients were assigned randomly to rate-controlling drugs, allowing AF to persist, or rhythm-controlling antiarrhythmic drugs, to maintain sinus rhythm. RESULTS: The NYHA-FC worsened with time in both rate-control and rhythm-control groups, with no differences between groups. Presence of AF was associated with worse NYHA-FC (p < 0.0001). No differences were observed in Canadian Cardiovascular Society Angina Classification or MMSE scores. Six-minute walk distance improved over time in both study arms. On average, walk distance was 94 feet greater in the rhythm-control group (adjusted p = 0.049). CONCLUSIONS: Modest improvement in 6-min walk distance was noted in the rhythm-control arm. Presence of AF was associated with worse NYHA-FC. No difference in cognitive function was detected.
Aged↗
Noninvasive assessment of left atrial maximum dP/dt by a combination of transmitral and pulmonary venous flow.
OBJECTIVES: The study assessed whether hemodynamic parameters of left atrial (LA) systolic function could be estimated noninvasively using Doppler echocardiography. BACKGROUND: Left atrial systolic function is an important aspect of cardiac function. Doppler echocardiography can measure changes in LA volume, but has not been shown to relate to hemodynamic parameters such as the maximal value of the first derivative of the pressure (LA dP/dt(max)). METHODS: Eighteen patients in sinus rhythm were studied immediately before and after open heart surgery using simultaneous LA pressure measurements and intraoperative transesophageal echocardiography. Left atrial pressure was measured with a micromanometer catheter, and LA dP/dt(max) during atrial contraction was obtained. Transmitral and pulmonary venous flow were recorded by pulsed Doppler echocardiography. Peak velocity, and mean acceleration and deceleration, and the time-velocity integral of each flow during atrial contraction was measured. The initial eight patients served as the study group to derive a multilinear regression equation to estimate LA dP/dt(max) from Doppler parameters, and the latter 10 patients served as the test group to validate the equation. A previously validated numeric model was used to confirm these results. RESULTS: In the study group, LA dP/dt(max) showed a linear relation with LA pressure before atrial contraction (r = 0.80, p < 0.005), confirming the presence of the Frank-Starling mechanism in the LA. Among transmitral flow parameters, mean acceleration showed the strongest correlation with LA dP/dt(max) (r = 0.78, p < 0.001). Among pulmonary venous flow parameters, no single parameter was sufficient to estimate LA dP/dt(max) with an r2 > 0.30. By stepwise and multiple linear regression analysis, LA dP/dt(max) was best described as follows: LA dP/dt(max) = 0.1 M-AC +/- 1.8 P-V - 4.1; r = 0.88, p < 0.0001, where M-AC is the mean acceleration of transmitral flow and P-V is the peak velocity of pulmonary venous flow during atrial contraction. This equation was tested in the latter 10 patients of the test group. Predicted and measured LA dP/dt(max) correlated well (r = 0.90, p < 0.0001). Numerical simulation verified that this relationship held across a wide range of atrial elastance, ventricular relaxation and systolic function, with LA dP/dt(max) predicted by the above equation with r = 0.94. CONCLUSIONS: A combination of transmitral and pulmonary venous flow parameters can provide a hemodynamic assessment of LA systolic function.
Adult↗
Atrial natriuretic factor improves renal function and lowers systolic blood pressure in renal allograft recipients treated with cyclosporin A.
OBJECTIVE: Atrial natriuretic factor (ANF) has several properties which suggest that it may ameliorate cyclosporin A nephrotoxicity. We therefore investigated the response to a pharmacological dose of ANF in renal transplant recipients treated with cyclosporin A. DESIGN: A single-blind randomized crossover design comparing the renal and haemodynamic effects of D-glucose (placebo) with ANF. METHODS: Seven patients with stable renal function following renal transplantation were studied under maximal water diuresis. Glomerular filtration rate and effective renal plasma flow were estimated from clearances of inulin and para-aminohippurate, respectively. RESULTS: Plasma ANF levels increased significantly in association with increased diuresis and natriuresis. Glomerular filtration rate was unchanged after placebo but increased significantly after ANF fusion. Likewise, effective renal plasma flow increased significantly with ANF infusion. There was a significant fall in systolic blood pressure, with no apparent change in heart rate and diastolic blood pressure. CONCLUSIONS: These results suggest that ANF may have beneficial effects in protecting against cyclosporin A-induced nephrotoxicity and hypertension.
Atrial Natriuretic Factor↗