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PubMed1971

Pressure-flow studies in man: effect of atrial systole on ventricular function in mitral stenosis.

The effect of atrial contraction on left ventricular function in six patients with varying degrees of mitral stenosis was determined by utilizing the pressure gradient technique to measure instantaneous aortic blood flow and pressure. Aortic flow was measured as ventricular rate was controlled by right ventricular pacing to create A-V (atrioventricular) dissociation at varying rates (90-150 beats/min). At each heart rate, beats with preceding P waves, effective atrial systole, were grouped according to the duration of the P-R interval. Beats without P waves served as controls. There was always a significant increase in stroke volume, created by effective atrial systole, but the P-R interval at which it took place was different for each patient. There was no difference in the stroke volume for beats preceded by P waves having a P-R interval within the range of 0.05-0.20 sec. These beats were grouped for each patient, subjected to regression analysis, and compared to control beats. The absolute and percent change created by effective atrial systole was inversely proportional to the severity of the disease as determined by mitral valve orifice size. Effective atrial systole plays less of a role in augmenting left ventricular function in patients with mitral stenosis than in patients with normal valves.

Adult↗
PubMed1983

[Evaluation of left ventricular function in patients with atrial septal defect by exercise echocardiography].

In order to evaluate left ventricular function in atrial septal defect (ASD), 12 cases with ASD, 18 postoperative cases of ASD and 27 normal controls were examined by means of exercise echocardiography using supine bicycle ergometer (50 watts and 3 min). M-mode echocardiograms and left ventricular (LV) short-axis views by two-dimensional echocardiography were subjected to the observation. M-mode echocardiographic studies: ASD group showed an increased stroke dimension (SD) during exercise mainly due to a marked increase of left ventricular end-diastolic dimension ( LVDd ) and a slight decrease of left ventricular end-systolic dimension ( LVDs ). Postoperative ASD group showed an increased SD during exercise mainly due to a marked decrease of LVDs and a slight decrease of LVDd . On the other hand, in normal control group exercise increased SD only by a significant decrease of LVDs . Right ventricular dimension was decreased during exercise in ASD group, but did not change significantly in postoperative ASD and normal control groups. During exercise in ASD group, peak velocity of circumferential fiber shortening (VCF) was increased most markedly, and negative peak VCF was decreased most strikingly. Eight of 12 patients with ASD who showed abnormal interventricular septal motion demonstrated remarkable improvement of the motion during exercise. Two-dimensional echocardiographic studies: Left ventricular short-axis views demonstrated that the shape of the left ventricular cavity changed from flattened to more circular configuration during exercise at end- and early-diastole in ASD group. The shape of the left ventricular cavity at late-systole did not change significantly during exercise in this group. In postoperative ASD group, the left ventricular short-axis view demonstrated circular configuration of the left ventricle at end-diastole both in rest and during exercise. The shape of the left ventricular cavity did not change by exercise. It was concluded that in ASD group cardiac output is increased during exercise by decreasing a left to right shunt at the atrial level and increasing left ventricular filling rate. Therefore, the left ventricular function was found to be good in ASD.

Adolescent↗
PubMed1995

Tolerance and effects of almokalant, a new selective Ik blocking agent, on ventricular repolarization and on sino-atrial and atrioventricular nodal function in the heart: a study in healthy, male volunteers utilizing transesophageal atrial stimulation.

Almokalant, (4-(3-ethyl(3-propylsulfinyl)propyl)amino)-2-hydroxy-propoxy)- benzonitrile), is a newly developed Ik channel blocker that exhibits pure class III effects. Using a noninvasive approach with transesophageal atrial stimulation (TAS), we wished to identify the dose of almokalant, given as an intravenous bolus infusion, that prolonged ventricular repolarization in the healthy human heart to an extent of potential clinical interest. Furthermore, we defined the electrophysiological effects of this dose on the heart, as well as the pharmacokinetics, safety, and tolerance throughout a wide dosing range. In the titration part, increasing doses were given to identify the dose that produced a reproducible QTend prolongation of approximately 20%. This dose (12.8 mumol) was then given in a placebo-controlled, double-blind, cross-over fashion. In the double-blind part, almokalant significantly prolonged the QTend intervals during sinus rhythm and during TAS at 100 beats/min and increased the effective refractory period of the atria (AERP). There was no alteration in either the cardiac conduction (PQ and QRS), or blood pressure (BP) sinus node function, or the ERP of the atrioventricular (AV) node. Therefore, almokalant exhibited pure class III effects with no signs of beta-blockade or unwanted hemodynamic effects. The plasma concentration-time curve showed a biexponential decrease with a terminal half-life (t1/2) of approximately 3 h. There was a large interindividual variation in the plasma concentration at the end of infusion, Cmax. This variability diminished considerably 60 min after infusion, and the pharmacokinetic characteristics studied appeared to be proportional to the dose. The drug was well tolerated, and the only side effect noted was a brief metallic taste after a dose of 25.6 mumol. Corresponding to high plasma peak values, T-wave morphology changes of short duration were observed, sometimes with the development of pronounced, biphasic T waves.

Adult↗
PubMed1993

Plasma levels of atrial natriuretic peptide and hemodynamic function in cardiac disease.

Plasma concentrations of atrial natriuretic peptide were measured in eight patients with cardiac disease but normal resting right atrial pressure, during cardiac catheterization. No patient had clinical evidence of overt heart failure. An increase in peptide concentrations was observed between the aorta or the peripheral vein and the pulmonary artery. A linear relation was found between peripheral vein and pulmonary artery peptide concentration. Mean pulmonary artery and capillary wedge pressure also correlated with the peptide levels. No correlation was observed between mean right atrial pressure and peptide concentration. These findings demonstrate that atrial natriuretic peptide release, even in the absence of cardiac failure, seems at least partly regulated by left atrial pressure. Finally, peripheral levels reflect the central concentrations of atrial natriuretic peptide.

Adult↗
PubMed1996

[Sinus node function, sinoatrial and atrial conduction and the nature of the course of supraventricular heart rate disorders in IHD patients before and after aortocoronary bypass].

Selective coronarography, assessment of hemodynamics, sinus node function, sinoatrial and intraatrial conduction were performed in 53 coronary heart disease (CHD) patients with supraventricular arrhythmia. The severity of cardiac rhythm paroxysms was evaluated at transesophageal pacing by measurements of arrhythmia induction frequency threshold. 29 patients underwent aortocoronary shunting. No relationships were found between the pattern of arrhythmia, degree of stenosis, number of coronary lesions. Aortocoronary bypass changed neither pattern nor severity of supraventricular arrhythmia.

Adult↗
PubMed1994

Incompetence of the foramen ovale in preterm infants supported by mechanical ventilation.

Fifty-one preterm infants (< 1500 gm) who were supported by mechanical ventilation were studied by use of serial color Doppler echocardiography to determine the hemodynamic impact of incompetence of the foramen ovale. Right and left ventricular stroke volume, measured by two-dimensional and Doppler echocardiography, were used to determine the ratio of pulmonary to systemic flow (Qp/Qs). The diameter of the color flow mapping of any interatrial shunt was measured together with pattern and velocity of that shunt. Ductal patency status was established. Most infants had some atrial shunting. The dominant direction of shunting was left to right within a bidirectional shunt pattern (75%). When the ductus was closed, there was a significant correlation between color Doppler diameter of the atrial shunt and Qp/Qs (r = 0.71). When this diameter was less than 2 mm, there was minimal impact on Qp/Qs. Measurable effects on Qp/Qs were usually seen at diameters > 3 mm when Qp/Qs ratios of up to 2:1 were recorded. Longitudinally, atrial shunting could be divided into four groups. Group 1 (n = 23) had minimal shunt or small shunts (< 3 mm) that resolved early, group 2 (n = 11) had small shunts that persisted, group 3 (n = 9) had large shunts (> 3 mm) that resolved, and group 4 (n = 6) had large shunts that persisted. Clinically there were no significant differences between the groups except that patients in groups 2 to 4 tended to having worse acute lung disease than patients in group 1 and had significantly more chronic lung disease. We conclude that many preterm infants have left-to-right atrial shunts that have a noninvasively measurable hemodynamic impact. This may have an effect on acute and chronic respiratory outcome and is likely to affect assessments of ductal shunting.

Atrial Function, Left↗
PubMed2005

Enalapril preserves sinus node function in a canine atrial fibrillation model induced by rapid atrial pacing.

METHODS AND RESULTS: Seventeen beagles were pretreated with either placebo (group I, n = 9) or enalapril 1 mg/kg/day (group II, n = 8) and paced at 500/min from the right atrial appendage for 4 weeks. Every week, corrected sinus node recovery time (CSNRT) and sinus cycle length (SCL) were measured. Quantitative analysis of interstitial fibrosis (IF) and adipose tissue (AT) in the SN was performed with Masson's trichrome stain, and apoptosis of the sinus nodal cells were detected with terminal deoxynucleotidyl transferase nick end-labeling. In group I, rapid atrial pacing prolonged both CSNRT and SCL. After 4 weeks of pacing, CSNRT and SCL were significantly shorter in group II (CSNRT, 410 +/- 37 msec; SCL, 426 +/- 34 msec) than in group I (CSNRT, 717 +/- 52 msec, P < 0.005; SCL, 568 +/- 73 msec, P < 0.05). Both IF and AT of the SN were greater in group I (IF, 9.7 +/- 1.9%; AT, 32.6 +/- 5.9%) than in seven sham dogs (IF, 2.4 +/- 0.9%, P < 0.05; AT, 4.0 +/- 1.7%, P < 0.05) and in group II dogs (IF, 4.0 +/- 2.0%, P < 0.05; AT, 4.0 +/- 1.7%, P < 0.05). End-labeling assay was positive in three of nine dogs in group I, but negative in group II and sham dogs. CONCLUSIONS: Rapid atrial pacing impaired SN function through IF and AT of the SN. Enalapril prevented these pacing-induced degenerative changes and improved SN function.

Analysis of Variance↗
PubMed2005

No correlation between atrial natriuretic peptide concentrations and echocardiographic measurements of left atrial size or left ventricular size and function in patients with persistent atrial fibrillation.

Atrial fibrillation (AF) may be associated with activation of atrial natriuretic peptide (ANP). The exact trigger for the release of ANP is still being debated. Atrial volume, pressure, and wall stretch are considered to be the main determinants of ANP activation. The aim of the study was to evaluate plasma ANP concentrations in patients with persistent AF and to analyze the echocardiographic determinants of ANP concentration in this group. The study population included 67 patients, 59 +/- 7 years of age, with a median AF duration of 5.5 months (range 0.1-12). The relationship between plasma ANP concentrations and echocardiographic left atrial (LA) diameter and volume, and left ventricular (LV) diameter and ejection fraction (EF) was analyzed by logistic regression analysis. The median baseline plasma ANP concentration was 63 pg/mL (range 21-126) in the study group versus 34 pg/mL (range 16-73) in a control group. The mean left antero-posterior atrial dimension, LA volume, LV enddiastolic diameter, and LVEF were 48 mm, 104 mL, 52 mm, and 54%, respectively. A significant linear positive correlation was found between plasma ANP concentration and maximal LA volume (r = 0.62, P < 0.01). A negative correlation was found between LVEF and plasma ANP concentration (r =-0.42, P = 0.01). However, by multivariate regression analysis, no echocardiographic parameter was an independent predictor of plasma ANP concentration. Plasma ANP concentrations were independent of echocardiographic measurements of LA size or LV size and function in patients with persistent AF.

Adult↗
PubMed1991

A noninvasive method of estimating mean pulmonary artery pressure in the pneumatic total artificial heart.

Accurate hemodynamic monitoring is essential for the clinical management of the recipient of a total artificial heart (TAH). The high incidence of pulmonary congestive disorders in this population complicates this already formidable task. Lack of diagnostic pulmonary artery pressure (PAP) information is recognized as a fundamental source of these problems. Because conventional methods of obtaining hemodynamic information are difficult to implement in TAH recipients, improvement of TAH case management depends on the development of innovative monitoring strategies. Noninvasive monitoring techniques have been developed for three (right atrial pressure, left atrial pressure, and aortic pressure) of the four auxiliary circulatory pressures used to quantify hemodynamic performance. Development of the fourth, for PAP, was the subject of this work. We developed a noninvasive, in vitro method of estimating mean PAP in the Jarvik-7 TAH (Symbion, Inc, Salt Lake City, UT) recipient. This information was obtained by analyzing the relationship between the pneumatic right drive pressure (RDP) and PAP waveforms produced by a Jarvik-7 (70 ml) connected to a Donovan mock circulation and driven by a Utahdrive System IIIe Controller (Symbion, Inc, Salt Lake City, UT). Total artificial heart driver parameters (i.e., heart rate, percent systole, and vacuum) were manipulated to produce a range of ventricular filling volumes (FV), from 40 to 60 ml, for three distinct states of the pulmonary vasculature: hypotensive, normal, and hypertensive. A unique multiple-linear regression equation was derived for each FV from the RDP-PAP relationship exhibited under these conditions. Comparison of computed estimates of PAP with actual measurements showed overall average correlations of greater than 0.92, with a standard error of the estimate of less than 1.9 mm Hg. The mean difference between actual and computed PAP measurements was -0.03 +/- 2.0 Hg. Estimations were accurate within 8.5% of true PAP values. Additional experimentation revealed that while the RDP-PAP relationships are dependent on FV, they are independent of the manner in which FV was obtained. Estimates proved useful over the clinical operating range of the pneumatic heart driver, as well as over the normal physiologic range of PAP in the human. This method is readily applicable to a computer-based monitoring implementation, although its effectiveness needs to be demonstrated in vivo.

Aorta↗
PubMed2001

Differential effects of dofetilide, amiodarone, and class lc drugs on left and right atrial refractoriness and left atrial vulnerability in pigs.

OBJECTIVES: Antiarrhythmic drugs have been shown to prolong right atrial refractoriness while data on the left atrium are not available. In pigs we have observed shorter effective refractory periods (ERP) of the left compared with the right atrium associated with a much higher left atrial vulnerability for tachyarrhythmias. Since this could suggest a different distribution of repolarizing ion channels in left and right atrium, we investigated whether antiarrhythmic drugs blocking different ion channels have a differential effect on left and right atrial ERP and left atrial vulnerability. METHODS: In pentobarbital-anesthetized pigs (n=40) we measured and compared ERPs in both atria before and after different drugs with the S1-S2 extrastimulus method at three basic cycle lengths (BCL) and assessed the inducibility of atrial fibrillation/flutter (AF/AFL) by the premature S2 stimulus. RESULTS: At the three BCL tested (240/300/400 ms) baseline ERPs were shorter in left vs. right atrium (112+/-2/124+/-2/129+/-2 ms vs. 147+/-2/163+/-2/167+/-2 ms, P<0.001). Mostly non-sustained AF/AFL induced by the S2 extrastimulus was very frequent in the left (68%) and nearly absent in the right atrium (3%). Only amiodarone, 5 mg/kg i.v., which showed a balanced increase of left and right atrial ERP (29+/-5/33+/-4/35+/-3% vs. 30+/-5/35+/-5/42+/-7%), decreased the inducibility of AF/AFL significantly (-72%, P<0.01). Dofetilide, 10 microg/kg i.v., had a stronger effect on right than left atrial ERP (36+/-4/39+/-5/46+/-10% vs. 23+/-2/22+/-7/22+/-5%, P<0.05), while flecainide, 1 mg/kg i.v., prolonged left more than right atrial ERP (58+/-15/36+/-7/40+/-7% vs. 26+/-5/24+/-5/21+/-4%, P<0.05) similar to 1 mg/ kg of propafenone (46+/-5/45+/-7/32+/-10% vs. 17+/-4/21+/-5/ 25+/-8%, P<0.05). CONCLUSION: The shorter refractoriness of the left compared with the right atrium observed in pigs was associated with a high left atrial vulnerability for tachyarrhythmias, which was reduced only by amiodarone showing a balanced increase of left and right atrial ERP. Dofetilide was stronger on right atrial ERP, flecainide and propafenone on left atrial ERP. These differences suggest a differential distribution of repolarizing ion channels between left and right atrium with possible relevance for the antiarrhythmic efficacy of drugs.

Amiodarone↗
PubMed1996

Effect of pneumoperitoneum on interatrial pressure gradient during laparoscopic cholecystectomy.

Alterations of the left atrial/right atrial pressure gradient were determined using a Swan-Ganz thermodilution catheter in 20 patients who underwent laparoscopic cholecystectomy with 12 mmHg pneumoperitoneum (LAP) and 13 patients who underwent minilaparotomy cholecystectomy (MINI). Right and left atrial pressures were both elevated by pneumoperitoneum. A diminished or reversed left/right interatrial pressure gradient was recognized during pneumoperitoneum in 4 of the 20 patients (20%) in the LAP group, whereas it was not recognized during operation in any of the 13 patients in the MINI group. Evaluation of the elevation of intrathoracic pressure during pneumoperitoneum using peak inspiratory airway pressure or pulmonary arterial pressure could not predict the occurrence of this paradoxical interatrial pressure gradient.

Atrial Function, Left↗
PubMed2003

Expression of angiotensin II receptors in human left and right atrial tissue in atrial fibrillation with and without underlying mitral valve disease.

UNLABELLED: TIVES: We postulated a change of angiotensin II receptor subtype expression in patients with lone atrial fibrillation (AF) and AF with underlying mitral valve disease (MVD) both compared with sinus rhythm (SR). BACKGROUND: Atrial fibrillation is a progressive disease associated with electrical and structural remodeling. Angiotensin II (ANGII) is involved in the process of myocardial remodeling. Actions of ANGII are mediated by ANGII receptor subtypes 1 and 2 (AT(1) and AT(2)). METHODS: Left atrial (LA) and right atrial (RA) tissue samples were obtained from patients with AF or SR with or without underlying MVD. The AT(1) and AT(2) protein levels were measured by quantitative Western blotting techniques. RESULTS: The AT(1) protein level in the LA was significantly increased in patients with AF (all forms) compared with SR (p < 0.05), whereas AT(2) expression was not significantly altered. Comparison of the subgroups revealed a similar increase of AT(1) in both paroxysmal AF and chronic AF with or without MVD. Additionally, investigations of ANGII receptor subtypes in the RA did not exhibit any significant changes either in AT(1) or in AT(2) in patients with AF versus SR. Underlying MVD did not significantly affect AT(2) receptor subtype expression in LA. CONCLUSIONS: Atrial fibrillation is associated with an up-regulation of AT(1) in LA, but not in RA, and did not appear to influence the AT(2) expression in the atrium. Because we found an enhanced expression of AT(1)in the LA, we conclude that AT(1) might be involved in the pathogenesis of AF in the LA.

Adult↗
PubMed2003

Assessment of the effects of various maneuvers on both atrial pressure changes.

The aim of the present study was to determine which maneuver causes the greatest pressure difference between both atria by measuring right and left atrial pressures simultaneously after certain maneuvers. Thirty-two coronary care unit patients, whom a Swan-Ganz catheter was inserted because of acute left ventricular dysfunction, hypotension, sinus tachycardia with unknown cause, were included in this study. The basal values of peak right atrium (RA) pressure and corresponding pulmonary capillary wedge pressure (PCWP) were measured via two separated transducers. Patients were tutored with several trials to perform breath holding, successive three strong coughs, Valsalva maneuver, 20 degrees head down, respectively. In the end of these maneuvers, the peak RA pressure and corresponding PCWP were measured simultaneously. All maneuvers caused an increase in RA pressure. The highest peak RA pressure was obtained by means of the Valsalva maneuver (7.6 +/- 5 versus 20.4 +/- 7.6 mmHg before and after Valsalva, respectively; P<0.001). PCWP (18.8 +/- 5.9 mmHg) increased only with coughing (21.2 +/- 6.7 mmHg, P<0.01) and 20 degrees head down maneuver (20 +/- 5.7 mmHg, P<0.05). The highest increase in pressure gradient between peak RA pressure and corresponding PCWP was observed during Valsalva maneuver (-11 +/- 6.6 vs. 2.3 +/- 5.9 mmHg, P<0.001). The lowest increase was obtained in 20 degrees head down maneuver (-11 +/- 6.6 vs. -8.5 +/- 5.8 mmHg, P<0.001). When measuring the pressure of both atria invasively and simultaneously, Valsalva maneuver was the most effective maneuver consistent with pressure difference in favour of RA among all the other maneuvers.

Atrial Function, Left↗
PubMed2000

Differences in organization between acute and chronic atrial fibrillation in dogs.

OBJECTIVES: The purpose of this study was to determine differences in acute and chronic atrial fibrillation (AF) "organization" in canine models. BACKGROUND: Electrophysiologic changes occur during atrial remodeling, but little is known about how remodeling affects AF organization. We hypothesized that atrial remodeling induced by long-term rapid atrial rates heterogeneously decreases AF organization. METHODS: In seven dogs, acute AF was induced by atrial burst pacing, and in eight dogs chronic AF was created by six weeks of continuous rapid atrial pacing. Atrial fibrillation was epicardially mapped from the right atria (RA) and left atria (LA). Atrial cycle length (CL), spatial organization and activation maps were compared. Spatial organization was quantified by an objective signal processing measure between multiple electrograms. RESULTS In acute AF, mean CL was slightly shorter in the LA (124 +/- 16 ms) than it was in the RA (131 +/- 14 ms) (p < 0.0001). In chronic AF, LA CL (96 +/- 14 ms) averaged 24 ms shorter than RA CL (121 +/- 18 ms) (p < 0.0001). Right atria and LA in acute AF had similar levels of organization. In chronic AF, the LA became approximately 25% more disorganized (p < 0.0001) while the RA did not change. In acute AF, a single broad wave front originating from the posterior and medial atrium dominated LA activation. In chronic AF, LA activation was more complex, sustaining multiple reentrant wavelets in the free wall and lateral appendage. CONCLUSIONS: Acute and chronic AF exhibit heterogeneous differences in CL, organization and activation patterns. The LA in chronic AF is faster and more disorganized than it is in acute AF. Differences in the models may be due to heterogeneous electrophysiologic remodeling and anatomic constraints. The design of future AF therapies may benefit by addressing the patient specific degree of atrial remodeling.

Acute Disease↗
PubMed1998

Restrictive left ventricular filling patterns are predictive of diastolic ventricular interaction in chronic heart failure.

OBJECTIVES: The purpose of this study was to determine whether restrictive left ventricular (LV) filling patterns are associated with diastolic ventricular interaction in patients with chronic heart failure. BACKGROUND: We recently demonstrated a diastolic ventricular interaction in approximately 50% of a series of patients with chronic heart failure, as evidenced by paradoxic increases in LV end-diastolic volume despite reductions in right ventricular end-diastolic volume during volume unloading achieved by lower body negative pressure (LBNP). We reasoned that such an interaction would impede LV filling in mid and late diastole, but would be minimal in early diastole, resulting in a restrictive LV filling pattern. METHODS: Transmitral flow was assessed using pulsed wave Doppler echocardiography in 30 patients with chronic heart failure and an LV ejection fraction < or = 35%. Peak early (E) and atrial (A) filling velocities and E wave deceleration time were measured. Left ventricular end-diastolic volume was measured using radionuclide ventriculography before and during -30-mm Hg LBNP. RESULTS: Nine of the 11 patients with and 2 of the 16 patients without restrictive LV filling patterns (E/A > 2 or E/A 1 to 2 and E wave deceleration time < or = 140 ms) increased LV end-diastolic volume during LBNP (p = 0.001). The change in LV end-diastolic volume during LBNP was correlated with the baseline A wave velocity (r = -0.52, p = 0.005) and E/A ratio (r = 0.50, p = 0.01). CONCLUSIONS: Restrictive LV filling patterns are associated with diastolic ventricular interaction in patients with chronic heart failure. Volume unloading in the setting of diastolic ventricular interaction allows for increased LV filling. Identifying patients with chronic heart failure and restrictive filling patterns may therefore indicate a group likely to benefit from additional vasodilator therapy.

Atrial Function, Left↗