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PubMed1996

A simplified method for the determination of left atrial size and function using cine magnetic resonance imaging.

This work aimed at developing a rapid and clinically applicable method for the assessment of left atrial size and function using magnetic resonance imaging (MRI). We studied 17 healthy subjects and 26 cardiac patients. Left atrial cine MRI with 50 ms phases was made in 6-12 contiguous long-axis sections encompassing the entire atrial cavity. A volume-time curve was reconstructed to measure the minimum and maximum volumes as well as the fractional volume change, reservoir function, ejection fraction, and mean filling and emptying rates of the left atrium. The image section with the largest left atrial area was then selected and a comparable area-time curve was reconstructed. The atrial phasic areas and functional indices were determined analogously to the volume-based assessment. The contours of atrial area-time and volume-time curves agreed closely in individual subjects. All area-based left atrial measurements distinguished cardiac patients as a group from healthy persons. The combined specificity of the area-based analyses was 92% and the sensitivity, 65%, in identifying abnormal results in individual patients. The accuracy of the area-based data was best for the atrial minimum size, fractional change, reservoir function, and mean filling rate. The estimated time savings with the simplified method were 5 to 6 h per patient. Left atrial size and function can be studied by reconstructing a phasic atrial area-time curve with cine MRI. Atrial enlargement and abnormalities of filling and reservoir function can be reliably identified, but if data on conduit or stroke function are crucial the three-dimensional MRI technique is still recommended.

Adult↗
PubMed2003

Left atrial appendage function and abnormal hypercoagulability in patients with atrial flutter.

STUDY OBJECTIVES: The prevalence of thromboembolism might be higher than previously recognized in patients with atrial flutter (AFL) based on findings of transesophageal echocardiography (TEE). To evaluate the potential prothrombotic state in patients with AFL, TEE findings and hemostatic markers were compared among patient groups with AFL, normal sinus rhythm (NSR) and chronic nonvalvular atrial fibrillation (AF). DESIGN AND SETTINGS: Cross-sectional study at a university hospital. METHODS: In 28 patients (mean age, 63 years) with AFL, 58 patients (mean age, 66 years) with AF, and 27 patients (mean age, 61 years) with NSR who underwent TEE, plasma levels of markers for platelet activity (platelet factor 4 and beta-thromboglobulin [beta-TG]), thrombotic status (thrombin-antithrombin III complex and prothrombin fragments 1 and 2) and fibrinolytic status (d-dimer and plasmin-alpha(2)-plasmin inhibitor complex) were determined. RESULTS: Left atrial appendage (LAA) blood flow velocity in patients with AFL was higher (p < 0.05) than that in patients with AF, but was lower (p < 0.05) than that in patients with NSR (AF, 25 +/- 2; AFL, 44 +/- 4; NSR, 60 +/- 4 cm/s). Dense left atrial spontaneous echo contrast (SEC) was found in 4 patients (14%) with AFL and 16 patients (28%) with AF. There was no significant difference in plasma levels of hemostatic markers between the AFL group and the NSR group. AFL patients with impaired LAA function (LAA flow < 30cm/s, dense SEC, or both), however, showed higher level of d-dimer and beta-TG than those without impaired LAA function (d-dimer, 1.9 +/- 0.6 microg/mL vs 0.4 +/- 0.1 microg/mL; beta-TG, 73 +/- 17 ng/mL vs 33 +/- 5 ng/mL, p < 0.05). CONCLUSIONS: Patients with AFL as a whole are not in the prothrombotic state as compared with those with AF. However, patients with AFL and impaired LAA function are at potentially high risk for thromboembolism and might require anticoagulation.

Aged↗
PubMed1999

Effect of radiofrequency ablation on atrial mechanical function in patients with atrial flutter.

Atrial stunning, as assessed by left atrial appendage emptying and increased spontaneous echo contrast, is known to occur following direct-current cardioversion of atrial fibrillation (AF) and atrial flutter (AFI). Little is known on atrial mechanical function and the time course of atrial recovery following radiofrequency ablation of AFI. Fourteen patients undergoing radiofrequency ablation of persistent typical counterclockwise AFI were enrolled. Two-dimensional and pulse Doppler transesophageal echocardiography (TEE) were performed before ablation and immediately following restoration of sinus rhythm. Left atrial spontaneous echo contrast grades, left atrial appendage emptying fractions, and peak left atrial appendage emptying velocities were measured. Transthoracic echocardiography (TTE) was performed immediately after ablation, then repeated after 1 day, 1 week, and 6 weeks to measure peak transmitral velocities and percent atrial contribution to ventricular filling. Left atrial appendage emptying velocities decreased significantly following AFI termination (44 +/- 23 cm/s before ablation vs 25 +/- 14 cm/s after ablation, p = 0.01). Left atrial appendage emptying fractions also decreased significantly (0.48 +/- 0.1 preablation vs 0.34 +/- 0.17 postablation, p = 0.02). New spontaneous echo contrast developed in 4 patients (29%) after ablation. Four patients had complete atrial standstill after ablation, and 1 patient developed a new left atrial appendage thrombus. The percent atrial contribution to ventricular filling recovered progressively over 6 weeks with significant improvement in peak transmitral velocities at day 7. Thus, atrial stunning occurs after catheter ablation of AFI and may lead to rapid formation of thrombus in the left atrial appendage. Significant improvement in left atrial function occurs in 7 days.

Aged↗
PubMed2001

[Function of the left atrial appendage after electrical cardioversion of atrial fibrillation to sinus rhythm].

INTRODUCTION: It is widely believed that atrial fibrillation appears in a secondly manner to atrial enlargement. Morfological alteration might be the source of disturbance of electrical activation and mechanical function to fibres that facilitate arrhythmia preservation as well as life threatening complications. THE OBJECTIVE: It is crucial to establish whether reversion of atrial fibrillation to sinus rhythm causes size diminishment and function improvement of the left atrial appendage, which creates hope to avoid dangerous complications, particularly systemic embolisation. DATA AND METHODOLOGY: 30 patients were qualified including 18 males and 12 females aged between 52 and 86 (average age was 63.81 +/- 9.22). All the patients suffered from nonrheumatic atrial fibrillation. The echocardiographic examination was conducted before reversion of atrial fibrillation, right after reaching sinus rhythm and after 6 months observation at sustained sinus rhythm. During the transesophageal echocardiographic examination the following parameters were investigated: LAApodł, LAApoprz, LAAobw, LAApole, LAAF, LAAB, LAAF intg, LAAB intg, spontaneous echocardiographic contrast, thrombus. RESULTS: Left atrial appendage size right after reversion of atrial fibrillation did not considerably differ from the values registered at the time of arrhythmia. It significantly diminished in the case of sustained stabilisation of sinus rhythm. The diminishment of the left atrial appendage size was connected with its function improvement expressed by increased maximum filling and emptying velocities as well as their integrals. SEC appearance frequency considerably increased right after reaching sinus rhythm. SEC appeared very rarely in the examination after 6 months. No single case of THR in LAA was noted. At the same time several cases of THR were disclosed both before and directly after restoration of sinus rhythm. CONCLUSIONS: Sinus rhythm restoration and its sustaining for a longer period of time results in size diminishing and function improvement of left atrial appendage. The stability of sinus rhythm is closely tied with thromboembolism risk factors.

Aged↗
PubMed2000

Management of patients with prosthetic heart valves: potential impact of valve site, clinical characteristics, and comorbidity.

Nearly four decades have passed since the first mechanical prosthetic aortic valve was placed. Since then several design changes and modifications have been made to improve longevity and hemodynamics and reduce thrombogenicity. Despite these advances thromboembolism remains the major problem for mechanical prosthetic valves. The type and the position of the prosthetic valve and several clinical characteristics such as age greater than 70, atrial fibrillation, depressed left ventricular systolic function, left atrial enlargement, left atrial thrombus and a prior history of systemic embolization influence the risk of thromboembolism and the level of anticoagulation needed to prevent this complication. Through clinical experience guidelines have been developed by the American College of Chest Physicians to determine the optimal level of anticoagulation needed to lower the thromboembolic rate with an acceptable hemorrhagic event rate.

Animals↗
PubMed2001

Doppler evaluation of systolic and diastolic heart failure in patients with cardiomyopathy.

BACKGROUND AND OBJECTIVES: Analysis of transmitral flow with Doppler echocardiography can currently evaluate left ventricular diastolic function noninvasively and easily. In addition, measurement of pulmonary venous flow and left atrial appendage flow clarifies not only left ventricular diastolic function but also left atrial systolic function in patients with left ventricular systolic failure and diastolic failure. METHODS AND RESULTS: Doppler echocardiography was used to investigate the differences in left ventricular diastolic dysfunction. In patients with systolic heart failure, left atrial dysfunction due to afterload mismatch to the left ventricle was related to the reduction of transmitral atrial filling wave in a restrictive pattern. In contrast, in patients with diastolic heart failure, transmitral flow seldom indicated a restrictive pattern because left atrial systolic function was preserved even with high pulmonary wedge pressure. CONCLUSIONS: Left ventricular diastolic dysfunction is somewhat distinct between patients with left ventricular systolic failure and patients with left ventricular diastolic failure. Atrial reversal flow in pulmonary vein has the potential to predict left ventricular filling pressure in patients with diastolic failure.

Cardiomyopathies↗
PubMed2006

Left atrial geometric and functional remodeling in athletes.

The aim of this study was to evaluate left atrial (LA) volume and its changes with the phases of atrial filling, and to examine the effect of exercise capacity on these parameters. Using two-dimensional echocardiography, LA volumes were measured in 30 male endurance runners and 30 age-matched sedentary men (controls). Maximal oxygen consumption (VO2max) was measured using a metabolic chart during exercise. LA reservoir, pump, and conduit functions, kinetic energy and force were calculated. We found that athletes had higher LA volume and volume index (except the conduit volume), LA passive emptying fraction, and LA total emptying fraction compared to control subjects. We observed positive correlations between: VO2max and LA passive emptying fraction (r=0.49, p<0.05); VO2max and LA active emptying fraction (r=0.54, p<0.05); VO2max and LA kinetic energy (r=0.61, p<0.05); and VO2max and LA force (r=0.57, p<0.05). These findings suggest that atrial function reflects exercise capacity in athletes.

Adult↗
PubMed1996

Characterization of left atrial appendage Doppler flow in atrial fibrillation and flutter by Fourier analysis.

The aim of this study was to characterize left atrial appendage mechanical function in atrial fibrillation and flutter by Fourier analysis to analyze frequency and regularity of flow. Left atrial appendage function is central to a patient's risk for thromboembolism. Although the function of the appendage can be analyzed by Doppler echocardiography in sinus rhythm, its mechanical function in atrial fibrillation and flutter has not been well characterized. This lack of adequate definition is caused by the complexity and temporal variability of the Doppler flow profiles. We assessed left atrial appendage function in 21 cases of atrial fibrillation (n - 11) and flutter (n = 10) and five in sinus rhythm with transesophageal Doppler echocardiography. Doppler profiles were examined by Fourier analysis, and the power spectra compared and analyzed between patients with atrial fibrillation and flutter. Left atrial appendage Doppler flow in atrial fibrillation produced Fourier spectra over a narrow band of frequencies with a peak frequency of 6.2 +/- 1.0 Hz, significantly higher than in atrial flutter (3.9 +/- 0.6 Hz, p < 0.00001). Additionally, a significant difference in subharmonic modulation (spectral power below the peak frequency) was observed between atrial appendage flow in atrial fibrillation and flutter, because 37% +/- 16% of the total spectral power was achieved before the dominant frequency in atrial fibrillation compared with 20% +/- 14% in atrial flutter (p = 0.02). Conversely, patients in sinus rhythm exhibited broad-banded Fourier spectra with most of the power in discrete frequency spikes at harmonics above the fundamental frequency with very little subharmonic modulation (1% +/- 0.05%). Left atrial appendage function in atrial fibrillation and flutter can be well characterized by Fourier analysis of Doppler flow. Atrial fibrillation has higher dominant frequencies and greater subharmonic modulation compared with flutter. Moreover, atrial fibrillation demonstrated quasiperiodic contraction patterns typically found in chaotic systems. Fourier analysis of left atrial appendage contraction patterns may therefore have significant promise in providing insights into mechanisms of atrial fibrillation and thromboembolism.

Aged↗
PubMed2002

Assessment of the left atrial appendage mechanical function by three-dimensional echocardiography.

AIMS: We evaluated the feasibility of three-dimensional echocardiography, in the assessment of left atrial appendage (LAA) function. METHODS AND RESULTS: Forty-five patients underwent multiplane transoesophageal echocardiography. In addition to Doppler and two-dimensional echocardiography, data for three-dimensional echocardiography reconstruction were obtained during transoesophageal echocardiography. Left atrial appendage ejection fraction based on three-dimensional echocardiography volume measurements (EFv) and two-dimensional echocardiography area measurements (EFa), coupled with other echocardiographic data, were related to left atrial appendage late peak emptying velocity, a frequently used indicator of left atrial appendage function. Multiple regression analysis has revealed a significant association of peak emptying velocity with EFv (P<0.0001), spontaneous echocardiographic contrast (P=0.001), tricuspid regurgitation (P=0.03) and left ventricular hypertrophy (P=0.05). No significant relation was observed between peak emptying velocity and EFa, presence or absence of atrial fibrillation, left ventricular dysfunction, mitral stenosis and insufficiency, left atrial dilatation, pulmonary venous peak systolic, diastolic and peak reverse flow velocity at atrial contraction as well as left atrial appendage volumes derived from two-dimensional echocardiography and three-dimensional echocardiography. In a simple linear correlation, the degree of association between peak emptying velocity and EFv was higher as between peak emptying velocity and EFa (r=0.7 vs 0.4, both P<0.001). Observer variabilities for calculating EFv were considerably lower than for two-dimensional echocardiography derived EFa. Ejection fractions determined by two-dimensional echocardiography area measurements at 45 degrees, 90 degrees and 135 degrees cutplane angulations were related to EFv only at 135 degrees. CONCLUSIONS: Left atrial appendage ejection fraction calculation by three-dimensional echocardiography is feasible, more accurate than by two-dimensional echocardiography and has lower observer variability. Furthermore, an optimal cutplane angulation of the left atrial appendage view at 135 degrees has been demonstrated.

Adult↗
PubMed1998

Left atrial systolic and diastolic function accompanying chronic rapid pacing-induced atrial failure.

The objective of this study was to examine the hypothesis that long-term, rapid atrial pacing produces a model of atrial systolic and diastolic dysfunction but does not alter ventricular function. Eight dogs were atrially paced at 400 beats/min (3:1-5:1 ventricular response) for 6 wk and subsequently instrumented with left atrial (LA) and left ventricular (LV) sonomicrometers and micromanometers. Data were compared with those from six sham-operated controls at matched heart rates and mean LA pressures of 10 mmHg. Dogs with rapid pacing had slightly greater LA volume (10.3 +/- 4.0 vs. 7.9 +/- 4.4 ml) and reduced ejection fraction (2.2 +/- 1.4 vs. 13.0 +/- 4.0, P < 0.05), systolic ejection rate (0.3 +/- 0.1 vs. 2.8 +/- 1.2 vol/s, P < 0.05), and reservoir fraction (0.07 +/- 0.04 vs. 0.35 +/- 0.06, P < 0.05) compared with controls. LA diastolic chamber stiffness was greater after rapid atrial pacing than before (stiffness constant kc, 5.7 +/- 2.3 vs. 3.4 +/- 0.6, P < 0.05), and the ratio of transesophageal echo-determined pulmonary venous systolic to diastolic integrated flow (a measure of relative reservoir to conduit function of the LA) was less in rapidly paced dogs compared with control dogs (0.41 +/- 0.19 vs. 0.68 +/- 0.23, P < 0.05). In contrast, rapid atrial pacing did not influence LV systolic performance or lusitropy, because the LV pressure time derivative and the time constant of LV relaxation were similar in both groups. In this model of isolated atrial myopathy, increased atrial stiffness and enhanced conduit function compensate for impaired atrial booster pump and reservoir functions.

Animals↗
PubMed1977

Cardiac function in total anomalous pulmonary venous return before and after surgery.

Cardiac performance was evaluated in 12 infants with isolated total anomalous pulmonary venous return. Four had significant pulmonary venous obstruction and severe pulmonary hypertension (group A). Eight had no obvious venous obstruction, and the pulmonary pressures were lower (group B). In all subjects, right ventricular end-diastolic volume was increased (197% of predicted normal) and its ejection fraction was normal. Left ventricular volume was, generally speaking, still in the normal range (87% of predicted normal); however, its ejection fraction was reduced (0.57 vs normal of 0.73) and left ventricular output was low (3.08 L/min/m2 vs normal of 3.98). Left atrial volume was consistently small (53% of predicted normal) with an appendage of normal size. The infants in group A had smaller chamber volumes/m2 BSA than those in group B. Left atrial function was abnormal, characterized by reduced reservoir function and a greater role as "conduit" from right atrium to left ventricle. Left atrial size was not found to be critical in the surgical repair of TAPVR. Cardiac function is restored to normal following surgery.

Angiocardiography↗
PubMed2000

The effects of streptozotocin-induced diabetes and aldose reductase inhibition with sorbinil, on left and right atrial function in the rat.

Diabetes mellitus is frequently associated with the complications of cardiovascular disease. Activation of the aldose reductase (or polyol) pathway has long been implicated as an underlying factor for the development of many diabetic complications and indeed, treatment with aldose reductase inhibitors has been shown to prevent or reverse many of these diabetic complications. This study examines the effects of 14-day streptozotocin-induced diabetes on alpha1- and beta-adrenoceptor-mediated responses in rat isolated left and right atria. The effects of treatment with the aldose reductase inhibitor (ARI) sorbinil were also studied. A positive inotropic response was observed to both isoprenaline and phenylephrine in left atria. Diabetes of 14 days duration resulted in a supersensitivity of these tissues to the beta-adrenoceptor agonist in comparison with controls, while responses to the alpha1-adrenoceptor agonist were unaltered. Spontaneously beating right atria from diabetic rats was found to have a depressed resting rate compared with control tissues, although positive chronotropic beta-adrenoceptor-mediated responses were not affected by diabetes. Phenylephrine produced alpha1-adrenoceptor-mediated chronotropic responses in right atrial tissues, and these were found to be enhanced in rats with diabetes. Treatment of diabetic rats with the ARI sorbinil was successful in preventing only one of the observed diabetes-induced changes in atrial function, namely the supersensitivity of left atria to isoprenaline. Sorbinil treatment did, however, alter responses of control left and right atria in a manner similar to diabetes. In conclusion, streptozotocin-induced diabetes of 14 days duration was found to cause a number of alterations in the functioning of both left and right atria. ARI treatment with sorbinil failed to prevent all but one of these changes, and in addition altered responses of atria from control rats, having a similar effect to that produced by diabetes. These data suggest that sorbinil may have effects in addition to, and independent of, aldose reductase inhibition in the cardiovascular system.

Aldehyde Reductase↗
PubMed1994

Relation of left atrial volume and systolic function to the hormonal response in idiopathic dilated cardiomyopathy.

We studied the relation of left atrial mechanical function to the hormonal response in 14 patients with idiopathic dilated cardiomyopathy. Left atrial volumes were echocardiographically measured at mitral valve opening (maximal), at onset of atrial systole (onset of the P wave of the electrocardiogram) and at mitral valve closure (minimal) from the apical 2- and 4-chamber views using the biplane area-length method. Left atrial systolic function was assessed with the left atrial active emptying fraction ([volume at onset of atrial systole-minimal]/[volume at onset of atrial systole]). Plasma renin activity, aldosterone and atrial natriuretic peptide plasma levels were determined using commercially available kits. Left atrial maximal volume was directly, and left atrial active emptying fraction was inversely related to plasma renin activity (r = 0.60, P = 0.02 and r = -0.59, P = 0.026, respectively), aldosterone (r = 0.61, P = 0.02 and r = -0.53, P = 0.048) and atrial natriuretic factor (r = 0.79, P = 0.0009 and r = -0.62, P = 0.01) plasma levels. Thus, increased left atrial size and depressed left atrial contractile performance are associated with increased hormonal response in idiopathic dilated cardiomyopathy.

Adult↗
PubMedDate not supplied

Left and right atrial transport function after the Maze procedure for atrial fibrillation: an echocardiographic Doppler follow-up study.

OBJECTIVES: We evaluated atrial transport function after the Maze procedure in long-term follow-up and compared left and right atrial function in Maze patients with that of healthy age-matched controls using echo Doppler techniques. BACKGROUND: The Maze procedure is designed to eliminate atrial fibrillation, restore normal sinus rhythm, and preserve atrial contraction. Initial data indicate that atrial transport function is restored in most patients undergoing the Maze procedure. The long-term echo Doppler evaluation of patients after the Maze procedure has not been well described. METHODS: We performed pulsed-wave Doppler and two-dimensional echocardiographic studies on 31 patients (24 men, mean age 53.8 years) who underwent the Maze procedure and who had a follow-up study greater than 3 months (mean 16.5 months) after the procedure. Measurements included peak left ventricular and right ventricular inflow A-wave velocity, maximum and minimum left atrial and right atrial areas, and fractional area change of the left and right atria. Results were compared with those obtained from 15 age-matched control subjects (11 men, mean age 53.8 years). RESULTS: Twenty-two patients (71%) had left atrial function shown by the presence of left ventricular inflow A-wave, and 25 patients (81%) had right atrial function shown by the presence of right ventricular inflow A-wave on Doppler echocardiography. The left ventricular inflow A-wave velocity was significantly lower than that of age-matched controls (37.5 +/- 15.5 versus 61.0 +/- 13.9 cm/sec; p < 0.001), whereas the right ventricular inflow A-wave velocity did not significantly differ between patients and control subjects (35.4 +/- 9.9 versus 35.3 +/- 4.9 cm/sec; p = Not significant). Although left and right atrial areas decreased significantly after the procedure, there was no significant change in the fractional area change which was smaller in Maze patients than control individuals. CONCLUSIONS: (1) In long-term follow-up of 16.5 months after the Maze procedure, left atrial systolic function was preserved in 71% of our patients and right atrial systolic function was preserved in 81%; (2) the left ventricular inflow peak A-wave velocity after Maze is considerably less than that in age-matched controls; and (3) left and right atrial sizes decreased after the procedure with no change in the fractional area change. These findings suggest that the Maze procedure is effective in restoring atrial function in the majority of patients; however, restored function is less than in control individuals.

Adult↗
PubMed1993

Estrogen-induced left ventricular chamber enlargement in ewes.

We studied the chronic effect of administration of a single large intramuscular dose of 17 beta-estradiol on left ventricular chamber size and output in the ewe. Fourteen oophorectomized ewes were successfully instrumented and studied, with measurements made of left ventricular, aortic, right and left atrial pressures, left ventricular stroke volume, and left ventricular minor axis dimension. Unanesthetized ewes were studied before and 1, 2, and 3 wk after intramuscular administration of 0.6 mg/kg 17 beta-estradiol (7 ewes) or 1.5 ml sesame oil placebo (7 ewes). Left ventricular end-diastolic pressure-end-diastolic dimension (LVEDP-EDD) and left ventricular end-diastolic pressure-stroke volume (LVEDP-SV) relationships were quantified during graded inferior vena caval occlusion and volume infusion. Left ventricular end-diastolic diameter was larger after estrogen but not after placebo administration. The LVEDP-EDD relationship shifted progressively rightward, indicating left ventricular chamber enlargement in the estrogen group but was unchanged in the placebo group. The plateau limb of the LVEDP-SV relationship in the estrogen group shifted up from a mean stroke volume of 77.1-89.5 ml/beat and did not change in the placebo group. We conclude that administration of a single large intramuscular dose of 17 beta-estradiol resulted in left ventricular chamber enlargement and increased stroke volume in the ewe.

Animals↗