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Results for “Atrial Function, Right”

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PubMed2000

Hemodynamic changes and right heart support during vertical displacement of the beating heart.

BACKGROUND: Hemodynamic instability during heart displacement in off-pump multivessel coronary artery bypass grafting might be related to right heart dysfunction. The Enabler (HemoDynamics Systems Ltd, Upper Yoqneam, Israel) is a cannula pump that expels blood from the right atrium into the pulmonary artery. We studied the hemodynamic changes and the role of the enabler during heart displacement. METHODS: Nine anesthetized sheep were assessed for hemodynamic changes during 90-degree heart displacement with or without Enabler support. Hemodynamic parameters included cardiac output, systemic arterial blood pressures, and left and right heart filling pressures. RESULTS: Heart displacement caused a significant decrease in cardiac output and systemic blood pressure (46%+/-5%, p = 0.001; and 20%+/-5%, p = 0.009, respectively), with a concomitant 137%+/-24% (p = 0.003) increase in central venous pressure. No significant change in left atrial pressure was observed. Activation of the Enabler caused a significant increase in cardiac output and systemic blood pressure (67%+/-15%, p = 0.01; and 17%+/-7%, p = 0.04, respectively), as well as a decrease in central venous pressure by 49%+/-8% (p = 0.0001). CONCLUSIONS: Heart displacement causes hemodynamic instability mainly by right heart dysfunction. The Enabler significantly stabilized circulation during vertical displacement of the beating heart.

Animals↗

PubMed1995

Structure-activity relationships of alkylxanthines: alkyl chain elongation at the N1- or N7-position decreases cardiotonic activity in the isolated guinea pig heart.

Relationships between the alkyl substitutions (C1-C6) and cardiac inotropic activities of xanthine derivatives were studied in isolated guinea pig heart muscles. Most of the alkylxanthines exhibited positive inotropic activity on the left atrium, which was increased with an elongation of alkyl chain at the N3-position but decreased by substitution of a long alkyl group at the N1- or N7-position of the xanthine skeleton. Although positive inotropic activity in the right ventricular papillary muscle was also increased by longer alkyl groups at the N3-position, the inotropic activity became negative with an increment in alkyl chain length at the N1- or N7-position. The positive inotropic activity of alkylxanthines was correlated with their inhibitory activity on the phosphodiesterase (PDE) III isoenzyme. Adenosine A1 antagonism and PDE IV inhibitory activity were also partly associated with the inotropic activity because H-89, an inhibitor of cyclic AMP-dependent protein kinase, diminished the positive inotropic action and potentiated the negative inotropic action. These results indicate that the positive inotropic activity of alkylxanthines becomes weak with elongation of alkyl chains at the N1- and N7-positions; In particular, xanthines having two long alkyl chains show a negative inotropic activity on the right ventricular papillary muscle, an effect that could not be elucidated from their cyclic AMP-dependent action.

Adenosine↗

PubMedDate not supplied

Flail tricuspid leaflet after multiple biopsies following orthotopic heart transplantation: echocardiographic and hemodynamic correlation.

Flail tricuspid leaflet has been reported as a relatively uncommon complication of endomyocardial biopsy in orthotopic heart transplant recipients. However, the relationship of this complication to the number of biopsies performed and to the site of access for biopsy is not known. The objectives of this study were to assess the prevalence of flail tricuspid leaflet/torn chordae tendineae in our recent transplant population, define the relationship of this complication to endomyocardial biopsy, and to correlate echocardiographic assessments of tricuspid regurgitation severity with hemodynamic data obtained at cardiac catheterization. From January 1991 to March 1993, 181 patients who had undergone orthotopic heart transplantation at our institution were evaluated with echocardiography for the presence of a flail leaflet or torn chordae tendineae of the tricuspid valve and tricuspid regurgitation. After identifying this complication in patients, we reviewed their hemodynamic tracings and biopsy protocols from the catheterization laboratory. The hemodynamic tracing chosen was that which was done at the time the flail leaflet was first diagnosed. Of the 181 patients, 21 (11.6%) had flail leaflet or torn chordae tendineae of the tricuspid valve. The group comprised 18 male and 3 female patients. The mean duration from the time of transplantation was 42 months (range, 1 to 87 months). The mean number of biopsies performed per patient was 15.5 (range, 2 to 27). The mean severity of tricuspid regurgitation by echocardiography was grade 3 (moderate); seven patients (33%) had severe regurgitation. The mean right atrial v wave by catheterization was 15 mm Hg (range, 6 to 26 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Function, Right↗

PubMed2002

Extended distribution of prolonged and fractionated right atrial electrograms predicts development of chronic atrial fibrillation in patients with idiopathic paroxysmal atrial fibrillation.

INTRODUCTION: This study evaluates whether electrophysiologic abnormalities in patients with idiopathic paroxysmal atrial fibrillation (PAF) predict the transition to chronic atrial fibrillation (CAF). METHODS AND RESULTS: Ninety-six patients with idiopathic PAF underwent electrophysiologic study and were followed up. During electrophysiologic study, endocardial mapping was performed at 12 sites in the right atrium (four aspects of the high, middle, and low right atrium). During follow-up of 60 to 130 months, conversion from PAF to CAF was observed in 17 patients (CAF group). The remaining 79 patients remained in sinus rhythm (PAF group). Although a high frequency of abnormal atrial electrograms was observed in the high right atrium in both groups, the frequency of those recorded from the middle right atrium was significantly higher in the CAF group than in the PAF group (70.6% vs 13.9%, P < 0.0005). Kaplan-Meier analysis showed that >50% of the patients with abnormal atrial electrograms in the middle right atrium developed CAF after 10 years, whereas only 7% of patients without those developed CAF (P < 0.0001). CONCLUSION: Our data suggest that extended distribution of abnormal atrial electrograms from the high to middle right atrium is predictive of the development of CAF in patients with idiopathic PAF.

Adult↗

PubMed2002

Echocardiographic predictors of adverse outcomes in primary pulmonary hypertension.

OBJECTIVES: The aim of this study was to evaluate the relationships between echocardiographic findings and clinical outcomes in patients with severe primary pulmonary hypertension (PPH). BACKGROUND: Primary pulmonary hypertension is associated with abnormalities of right heart structure and function that contribute to the poor prognosis of the disease. Echocardiographic abnormalities associated with PPH have been described, but the prognostic significance of these findings remains poorly characterized. METHODS: Echocardiographic studies, invasive hemodynamic measurements and 6-min walk tests were performed and outcomes prospectively followed in 81 patients with severe PPH. Subjects were participants in a 12-week randomized trial examining the effects of prostacyclin plus conventional therapy compared with conventional therapy alone. RESULTS: During the mean follow-up period of 36.9 +/- 15.4 months, 20 patients died and 21 patients underwent transplantation. Pericardial effusion (p = 0.003) and indexed right atrial area (p = 0.005) were predictors of mortality. Pericardial effusion (p = 0.017), indexed right atrial area (p = 0.012) and the degree of septal shift in diastole (p = 0.004) were predictors of a composite end point of death or transplantation. In multivariable analyses incorporating clinical, hemodynamic and echocardiographic variables, pericardial effusion and an enlarged right atrium remained predictors of adverse outcomes. Six-minute walk results, mixed venous oxygen saturation and initial treatment randomization were also independently associated with a poor prognosis. CONCLUSIONS: Pericardial effusion, right atrial enlargement and septal displacement are echocardiographic abnormalities that reflect the severity of right heart failure and predict adverse outcomes in patients with severe PPH. These characteristics may help identify patients appropriate for more intensive medical therapy or earlier transplantation.

Adult↗

PubMed1996

Contribution to heart rate variability by mechanoelectric feedback. Stretch of the sinoatrial node reduces heart rate variability.

BACKGROUND: Heart rate variability is an important prognostic indicator for sudden death. An increased risk of sudden death and arrhythmia is associated with reduced heart rate variability in heart failure. In heart failure, there is also dilatation of the atria, which raises the prospect that there could be some physiological basis to possibly link heart rate variability with atrial dilatation. We therefore investigated whether sustained atrial stretch could modulate heart rate variability directly. METHODS AND RESULTS: Pigs were anesthetized and their hearts exposed. A specially built device stretched the sinoatrial node before and after vagal section and then after administration of propranolol. Stretch of the sinoatrial node decreases heart rate variability in the following ways: The standard deviation of the beat-to-beat interval decreases (4.2 to 2.6 ms; P = .004), and the high-frequency components are reduced (control, 6.5 +/- 2.2 ms2, during stretch, 1.4 +/- 0.3 ms2, P = .003). After section of both vagi, the high-frequency components are reduced by stretch of the sinoatrial node (2.8 +/- 0.9 ms2 for control versus 1.2 +/- 0.3 ms2 during stretch; P = .05). Similarly, after both vagal section and beta-blockade, stretch of the sinoatrial node reduces the high-frequency components (10.6 +/- 3.5 ms2 for control verses 3.0 +/- 1.5 ms2 during stretch; P = .01). CONCLUSIONS: We conclude that stretch of the sinoatrial node reduces high-frequency heart rate variability. This may account in part for the reduced heart rate variability seen in clinical conditions in which the right atrium is dilated, such as congestive cardiac failure.

Adrenergic beta-Antagonists↗

PubMed2006

A dilated inferior vena cava is a marker of poor survival.

BACKGROUND: The inferior vena cava (IVC) morphology is often used to estimate right atrial pressure; however, the association of IVC morphology and outcome is poorly described. METHODS: We evaluated 4383 consecutive outpatients (98% men) undergoing echocardiography at 1 of 3 Veterans Affairs laboratories. RESULTS: Of the 3729 with adequate images, 3295 (88%) had a normal IVC (< 2 cm), 358 (10%) had a dilated IVC that collapsed at least 50% with inspiration, and 76 (2%) had dilated IVC that did not collapse. Compared with patients with a normal IVC, those with a dilated IVC were older (66 +/- 13 vs 69 +/- 12 years if dilated with collapse and 70 +/- 12 years if dilated without collapse, P = .0005) and were more likely to have a history of heart failure (11% vs 18% if dilated with collapse and 38% if dilated without collapse, P < .0001). The 90-day and 1-year survival rates were 99% and 95% for those with a normal IVC, 98% and 91% for those with a dilated IVC with collapse, and 89% and 67% for those with a dilated IVC without collapse (P < .0001). After adjustment for clinical and echocardiographic characteristics including left and right ventricular function and pulmonary artery pressure, a dilated IVC without collapse remained associated with increased mortality: hazard ratio 1.43 (1.29-1.57 compared with a normal IVC, P < .0001). CONCLUSION: A dilated IVC without collapse with inspiration is associated with worse survival in men independent of a history of heart failure, other comorbidities, ventricular function, and pulmonary artery pressure.

Aged↗

PubMed1994

Validation of continuous wave Doppler-determined right ventricular peak positive and negative dP/dt: effect of right atrial pressure on measurement.

OBJECTIVES: The present study aimed to validate the peak positive and negative values of the first derivative of right ventricular pressure (dP/dt) using Doppler echocardiography and to determine the impact of right atrial pressure on the measurements. BACKGROUND: A pressure gradient between the right ventricle and the right atrium can be obtained by continuous wave Doppler-derived tricuspid regurgitant velocity using the simplified Bernoulli equation. If right atrial pressure fluctuation during systole and isovolumic diastole were small compared with right ventricular pressure changes, right ventricular pressure could be evaluated, and maximal positive and negative dP/dt could also be determined with Doppler echocardiography. METHODS: We investigated 11 patients with a wide range of right atrial pressure with tricuspid regurgitation using simultaneous examination by Doppler ultrasound and catheterization. Hemodynamic conditions were altered by the Valsalva maneuver, and a total of 40 beats were analyzed. RESULTS: There was good correlation between Doppler-derived and catheterization-derived peak positive dP/dt (y = 1.0x - 15.4, r = 0.98, n = 40), irrespective of the level of right atrial pressure. Doppler-derived peak negative dP/dt also showed good correlation with that determined by catheterization (y = 0.9x + 58.2, r = 0.93, n = 40). However, in patients with high right atrial pressure (v wave pressure > or = 10 mm Hg), Doppler-derived peak negative dP/dt tended to show lower values than those from catheterization measurements, except in patients with pulmonary hypertension. CONCLUSIONS: We conclude that right ventricular dP/dt can be estimated by the Doppler method accurately and noninvasively. However, when right atrial pressure is relatively high compared with corresponding right ventricular pressure changes during isovolumic diastole, Doppler-derived peak negative dP/dt might underestimate catheter-derived measurements.

Adult↗

PubMed2004

Computational fluid dynamics-analysis of the Niagara hemodialysis catheter in a right heart model.

Central venous catheters are widely used as a hemoaccess method for dialysis therapy. In this study, the performance parameters (velocities, pressure drop, shear rates, access recirculation) of the Niagara catheter are analyzed using computational fluid dynamics. Side holes are left open, closed, or reduced in size to assess the influence of this design feature. Initially the catheter is inserted in a tube which represents the vena cava. In the "arterial" luminal tip, wall shear rates over 20,000 s(-1) are common and peaks attain 55,000 s(-1) at a 300 mL/min blood flow rate. The presence of side holes appears to affect the location but not the level of these elevated shear rates. Halving their diameter causes elevated shear rates to appear in a more extended region with peaks up to 80,000 s(-1). Simulated recirculation percentage is nil in normal catheter use, but attains 30% with reversed catheter connections. The results of the tube model are compared to those of an anatomically realistic right atrium model, which was three-dimensionally reconstructed. It is concluded that most catheter's specific hemodynamic properties can be deduced from the tube model.

Atrial Function, Right↗

PubMed1992

Thrombolytic therapy for right heart lesions.

Thrombolytic agents are accepted therapy for occlusion of coronary and peripheral arteries as well as for venous thromboses. Although the treatment of left heart prosthetic valve thrombosis has been evaluated, there are limited data showing the benefit of thrombolysis of right heart clots. Two patients with past histories of multiple cardiac operations were given fibrinolytic therapy for thrombosis involving right heart structures. The first patient had thrombosis of a prosthetic pulmonary valve. The second patient was a type IB tricuspid atresia who developed a Fontan duct stenosis and right atrial clot. Thrombolytic therapy may provide a safe alternative to surgical intervention for thrombosis of right heart structures and, even when incompletely effective, may provide additional time to prepare patients for surgical correction and possible protection against distal embolization during surgical intervention.

Adult↗

PubMed1994

Slow abnormal conduction in the low right atrium: its anatomic basis and relevance to atrial reentry.

To characterize slow abnormal conduction in the low right atrium, which is known to be responsible for atrial flutter, electrophysiologic findings were correlated with anatomic features in a canine model of atrial flutter with ligation of the crista terminalis in the midright atrium. Activation in the low right atrium was mapped with a patch electrode containing 52 bipolar electrodes and a multiplexing system. A particular region in the low right atrium showed atrioventricular node-like electrophysiologic properties, a rate-dependent conduction delay, and Wenckebach periodicity. This area coincided with an area responsible for slow conduction during atrial flutter and unidirectional block at its initiation. Both pilsicainide and E-4031 preferentially blocked conduction in the specific area, leading to the termination of atrial flutter. Although refractoriness could not explain the abnormal conduction, anatomic studies consistently found the specific region to be in or around a thick muscle bundle, that is, the crista terminalis, or a thick pectinate muscle branching from the crista, located perpendicular to the wavefront of the pacing impulse and atrial flutter. These electrophysiologic and anatomic findings suggest that slow abnormal and atrioventricular node-like conduction over a thick muscle bundle, which is a normal anatomic feature of the low right atrium, plays a role in the initiation, maintenance, and termination of atrial reentry.

Animals↗

PubMed2003

Role of relative changes in caval flows for evaluation of right atrial pressure shifts induced by nitroglycerin.

Experiments on cats treated with nitroglycerin showed dynamic relationship between changes in caval venous flows: blood flow increased in the superior vena cava and decreased in the inferior vena cava. Blood pressure in the right atrium either decreased, or increased. No significant changes in total venous return were observed during maximum shifts in right atrial pressure, while contractility of the right ventricular myocardium usually decreased. Our findings suggest that the direction of the right atrial pressure shifts induced by nitroglycerin does not depend on venous return, but is determined by the prevalence of flow changes in the superior vena cava or inferior vena cava.

Animals↗

PubMed1992

Nephrotic-range proteinuria associated with right atrial myxoma.

A case of right atrial myxoma presenting with right heart failure and proteinuria is described. Proteinuria was variable and this corresponded with the degree of systemic venous congestion. On one occasion the proteinuria was within the nephrotic range. There was no evidence of intrinsic renal pathology. The right heart failure and proteinuria resolved after tumour removal, suggesting that the etiology of urinary protein loss was a reversible increase in glomerular permeability.

Aged↗

PubMed1996

Acquired left ventricular to right atrial communication and complete heart block following nonpenetrating cardiac trauma.

Intracardiac shunts are uncommon cardiac lesions caused by blunt chest trauma. A very unusual case is reported of a young male with an acquired left ventricular to right atrial communication and complete heart block cause by nonpenetrating chest trauma. The left ventricular to right atrial fistula was diagnosed noninvasively by transthoracic and transesophageal echo-Doppler examination and the findings were confirmed by left ventriculography and by the intraoperative findings.

Adolescent↗

PubMed2005

Rate-dependent block in the sinus venosa of the swine heart during transverse right atrial activation: correlation between electrophysiologic and anatomic findings.

UNLABELLED: Rate-dependent block in the sinus venosa. INTRODUCTION: Whether the crista terminalis or the sinus venosa result in rate-dependent block during transverse activation of the right atrial activation remains unknown. In the present study, right atrial activation at different cycle lengths was studied in the swine heart using high-resolution noncontact mapping (Endocardial Solutions). The location of the block was tagged and correlated with postmortem anatomical findings. METHODS AND RESULTS: Eight pigs were studied using noncontact mapping to obtain right atrial geometry and detailed sequence of activation using noncontact endocardial mapping. During sinus rhythm, activation proceeded uninterrupted craniocaudally along the sinus venosa and crista terminalis with similar conduction velocities (1.08+/-0.17 and 1.17+/-0.14 m/sec, respectively). Proximal coronary sinus stimulation was used to create transverse activation of the posterior right atrial wall. A rate-dependent decrease in conduction velocity occurred in the sinus venosa region (0.93+/-0.21, 0.82+/-0.14, and 0.52+/-0.09 m/sec at 500, 400, and 300 ms, respectively; P<0.05). The line of block verified by isopotential mapping and double potentials was obtained at cycle lengths of 240+/-30 ms. This line of the block was tagged with radiofrequency current lesions. Postmortem, all lesions were located in the sinus venosa region, 9.8+/-4.1 mm from the posteromedial edge of the crista terminalis. This region showed abrupt changes in muscle fiber thickness and orientation as well as in collagen content. CONCLUSIONS: The sinus venosa and not the crista terminalis results in a rate-dependent line of block during transverse right atrial activation. The morphologic characteristics of the sinus venosa appear to facilitate block in this region.

Animals↗

PubMedDate not supplied

Atrial compliance changes in animal total artificial heart recipients.

Right atrial compliance of chronically implanted total artificial heart animals was calculated from the pressure-volume relationships acquired at autopsy and compared with those of a control animal. The chronically implanted animals showed right atrial dilatation and low compliance. Even though atrial dilatation and decreased compliance have an opposite direct effect on atrial pressures, these changes may, in turn, disturb stretch-dependent volume regulatory processes, resulting in high atrial pressure.

Animals↗

PubMed1994

The effects of dopamine and noradrenaline on cardiovascular function in patients with acute respiratory failure.

The short-term haemodynamic effects of terminating dopamine and/or a combination of noradrenaline and nitroglycerin infusions were studied in 21 patients in acute respiratory failure. Patients were studied during treatment and 10 min after infusions were stopped. Off treatment, stroke index and cardiac index decreased significantly from 40.2 to 36.9 ml m-2 (P < 0.02) and from 3.80 to 3.42 litres m-2 (P < 0.02), respectively. Cardiac filling pressures decreased significantly and systemic vascular resistance increased, when infusions were stopped. As to heart rate, mean arterial pressure, mean pulmonary arterial pressure, right and left ventricular ejection fraction there were no significant changes between the data obtained during and off treatment. Although the haemodynamic status was significantly better during treatment with dopamine and/or noradrenaline-nitroglycerin in some respects, the overall beneficial effects of inotropic support were much less than anticipated.

Acute Disease↗

PubMed1997

Mechanism of abrupt hypotension with stretch of right atrium during cardiac surgery.

During cardiac surgery abrupt hypotension sometimes occurs by the atrium being pulled, though the hypotensive mechanism is not known. The effects of mechanical stretching of the right atrium on haemodynamics and renal sympathetic nerve activity in the anesthetized rabbit was investigated. During stretching of the right atrial appendage with a metal weight (right atrial stretch), both mean arterial pressure (mAP) and renal sympathetic nerve activity significantly decreased. Bilateral vagotomy significantly reduced the change in mean arterial pressure with right atrial stretch (P < 0.01), and significantly increased renal sympathetic nerve activity (P < 0.01). The duration of the decreases of mean arterial pressure with right atrial stretch was significantly shortened after vagotomy. Decreases of blood flow of the descending aorta with right atrial stretch were observed and not affected by vagotomy. These results suggest that hypotension with mechanical stimulation of the right atrium is not only due to the decrease in cardiac output but also to sympathetic inhibition through the vagus via cardiac baroreflex.

Animals↗