Effect of linear radiofrequency ablation on left atrial function.
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Atrial Fibrillation↗
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Left atrial function is unchanged by implantable defibrillator shocks on hearts in sinus rhythm.
Sixteen patients in sinus rhythm at baseline undergoing implantable cardioverter-defibrillator implantation were monitored with transesophageal echocardiography both before and after direct current cardioversion with currents of 15 to 20 J, for any direct current induced atrial dysfunction. We found no change in the indexes of atrial function or appearance of spontaneous echo contrast in the immediate postshock period by intraoperative transesophageal echocardiography.
Atrial Function, Left↗
A clinical appraisal of left atrial function.
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Atrial Appendage↗
[Recovery of left atrial function after cardioversion of atrial fibrillation: the role of some clinical and echocardiographical factors].
Sinus rhythm was restored in 102 patients with atrial fibrillation. Cardioversion was spontaneous (n=6), pharmacological (n=35), and electrical - early (n=46) or postponed because of necessity of full anticoagulation (n=15). Irrespective of method of cardioversion all patients had signs of atrial stunning. Doppler echocardiography performed within 24 hours and in 3, 7 and 14 days after cardioversion showed that rate of recovery of mechanical left atrial function had pronounced individual variations. In patients with spontaneous termination of atrial fibrillation normalization of left atrial contractile activity occurred in about 3 days, after pharmacological cardioversion - in 1 week (in 91.4% of cases). After early and postponed electrical cardioversion mechanical left atrial function recovered in 2 weeks in 97.8 and 73.3% of patients, respectively. Most important impact on this process produced duration of the last attack of atrial fibrillation and left atrial dimensions.
Adult↗
Left atrial function in patients with renal transplantation.
BACKGROUND: Chronic renal failure leads to structural changes and cardiac functional abnormalities known as uremic cardiomyopathy. Eliminating excess water and improving the composition of the inner environment leads to at least partial cardiac function improvement, which is reflected primarily in favorable changes in left ventricular indices. The aim of our study was to evaluate left atrial function in patients after renal transplantation and compare them with clinically healthy subjects. MATERIAL/METHODS: 10 renal transplant patients (2 women, 8 men; mean age 47.8 +/- 6.4 years), treated before transplantation with repeated hemodialysis, were subjected to standard transthoracic echocardiographic examination. Atrial function was evaluated in M-mode and 2D projections and by cross-sectional Doppler echocardiography. The results obtained were compared with 16 healthy controls (9 women, 7 men; mean age 39.7 +/- 9.4 years). RESULTS: Maximal left atrial dimension (LAmax), left atrial dimension obtained in M-mode of the long axis in parasternal projection (LAa), ejection time (ETlp) and pre-ejection period (PEPlp) were significantly higher in renal transplant patients than in healthy subjects. In both investigated groups there were no differences in minimal left atrial dimensions (LAmin), PEPlp/Etlp ratio, P wave time (P), left atrial fiber shortening fraction (FS%lp), passive evacuate fraction (FBOlp), total left atrial fraction (FClp), or IElp ratio. CONCLUSIONS: Abnormal function of the left atrium in the course of uremia treated with repeated hemodialysis is not fully corrected after renal transplantation despite the elimination of many cardiovascular complications observed in chronic renal disease.
Adolescent↗
Changes in regional left atrial function with aging: evaluation by Doppler tissue imaging.
AIMS: This study applies pulsed wave Doppler tissue imaging and colour Doppler tissue imaging to study changes in atrial function with ageing. We tested the following hypotheses: (1) pulsed wave Doppler tissue imaging can detect global changes of left atrial function associated with ageing similar to standard echocardiographic methods, (2) colour Doppler tissue imaging can reproducibly detect regional changes in atrial function (wall motion) of the normal young and normal aging atrium. METHODS AND RESULT: We studied 92 healthy subjects, divided into Group B (>or=50 years) and Group A (<50 years). As a reference standard the conventional measures of atrial function were determined: peak mitral A wave velocity, A wave velocity time integral, atrial emptying fraction and atrial ejection force. Pulsed wave Doppler tissue imaging estimated atrial contraction velocity (A' velocity) in late diastolic and segmental atrial contraction was determined by colour Doppler tissue imaging. A' velocities were significantly higher in Group B vs Group A (9.8+/-1.8 vs 8.5+/-1.5cm/s; P=0.0005). A' velocity correlated with atrial fraction (r=0.28; P=0.007) and atrial ejection force (r=0.21; P=0.04). Age correlated significantly with atrial ejection force (r=0.47; P=0.0001), atrial fraction (r=0.61; P=0.0001) and A' velocity (r=0.4; P=0.0002). Longitudinal segmental atrial contraction using colour Doppler tissue imaging showed an annular to superior segment decremental gradient with contraction velocities higher in Group B vs Group A. CONCLUSION: Pulsed wave Doppler tissue imaging and colour Doppler tissue imaging are reproducible and readily obtained parameters that provide unique data about global and segmental atrial contraction. In this study, changes in atrial contraction with aging were consistent with increased atrial contribution to filling accomplished by augmented atrial contractility.
Adolescent↗
Evaluation of left atrial function by the functional volume change curve derived from Doppler flow spectra.
The objective of this study was to clarify the left atrial (LA) reservoir and booster pump function in patients with left ventricular (LV) diastolic dysfunction. To determine LA reservoir and booster pump function, a new algorithm to determine LA functional volume change curve (FVC) was developed from Doppler flow spectra of pulmonary venous flow and LV inflow by transthoracic echocardiography in 110 patients. Patients were classified into normal (N), and abnormal (AB) and pseudonormal (PN) groups on the basis of their Doppler flow patterns. From the indices of FVC, atrial reservoir volume (ARV), passive emptying volume (PEV) and active emptying volume (AEV) were obtained. ARV/stroke volume (SV) was increased in the AB group, but decreased in the PN group compared with N (N, 0.61+/-0.09; AB, 0.73+/-0.10; PN, 0.52+/-0.13, p<0.05). PEV/SV was significantly decreased in AB, but increased in PN compared with N (N, 0.27+/-0.07; AB, 0.19+/-0.07; PN, 0.31+/-0.18, p<0.05). AEV/SV was significantly increased in AB, but decreased in PN compared with N (N, 0.41+/-0.08; AB, 0.56+/-0.10; PN, 0.26+/-0.19, p<0.05). Thus, in patients with an abnormal relaxation pattern, the LA reservoir and booster pump function are augmented, but in patients with a pseudonormal pattern, both LA reservoir and booster pump function are deteriorated, suggesting a vulnerability to pulmonary congestion.
Adult↗
Left atrial function in congestive heart failure: assessment by transmitral and pulmonary vein Doppler.
The relation of transmitral flow patterns and pulmonary venous velocities was analyzed from 50 heart failure patients (28 men, 22 women; mean [+/- SD] age 61 +/- 9 years) with a left ventricular ejection fraction < 40%. Doppler echocardiography was performed in all patients. Transmitral flow measurements included early (E) and atrial (A) velocities and deceleration time of E wave (DT). Patients were assigned to two groups according to E/A ratio, DT, or both: 20 patients in the restrictive group, and 30 patients in the nonrestrictive group. Pulmonary venous flow was obtained by the transthoracic approach. Systolic (S), diastolic (D) and atrial reversal (Ar) velocities were measured. Of the study population, 13 patients had simultaneously determined pulmonary capillary wedge pressure (PCWP). The results showed a lower S (28 +/- 11 vs. 51 +/- 10 cm/sec, p < 0.01), a higher D (66 +/- 13 vs. 44 +/- 10 cm/sec, p < 0.01) and a smaller Ar (12 +/- 10 vs. 24 +/- 9 cm/sec, p < 0.01) in the restrictive group compared with those in nonrestrictive group. In the subgroup of patients undergoing invasive hemodynamic studies, there was no relationship between PCWP and atrial reversal velocity. However, a significant correlation was observed for pulmonary systolic (r = -0.70, p < 0.01) and diastolic (r = 0.76, p < 0.01) velocities to PCWP. These findings suggest a reduction in left atrial compliance and atrial systolic function and both play important roles in heart failure patients with the restrictive transmitral flow pattern.
Aged↗
Left atrial function as a predictor of haemodynamic response in patients with mitral stenosis: a dobutamine stress echocardiographic study.
OBJECTIVE: The mechanisms of the different haemodynamic and clinical responses to dobutamine infusion in mitral stenosis (MS) are not clearly established. The aim of this study was to evaluate the relation between left atrial (LA) function and haemodynamic response in patients with MS during dobutamine infusion. METHODS AND RESULTS: Forty-two consecutive moderately symptomatic patients (33 women, 9 men; mean age 46+/-9, range from 26 to 66), New York Heart Association (NYHA) class II with MS (mean mitral valve area 1.7+/-0.1 cm2) were evaluated with dobutamine stress echocardiography. Haemodynamic measurements were obtained at rest and during peak dobutamine infusion. LA fractional shortening at rest was used as an index of global LA function. Group I consisting of patients with significantly elevated pulmonary artery pressure (> 60 mm Hg) and mean transmitral gradient (> 15 mm Hg) at peak dobutamine infusion were defined as haemodynamically serious MS. Group II consisted of the remaining 30 patients whose haemodynamic data were below these levels. While baseline haemodynamic parameters and mitral valve characteristics were not different between the two groups, LA fractional shortening was significantly lower (18.9+/-2.8 vs. 32.3+/-5.1%, p<0.0001) and left atrial dimension was significantly larger in group I (49.7+/-2.3 mm vs 43.6+/-5.3 mm, p<0.0001). Left atrial fractional shortening was negatively correlated with the increase in mean transmitral gradient (r:-0.58, p<0.01). When the patients were divided using a LA fractional shortening level of 25% as the cut-off point, we observed that the patients with low LA fractional shortening had a greater increase in mean transmitral gradient (7.3+/-3.1 mm Hg vs. 4.6+/-1.4 mm Hg), p = 0.005) and pulmonary artery pressure (22.4+/-3.5 mm Hg vs. 16.1+/-8.5 mm Hg, p = 0.001) compared to the patients with high LA fractional shortening. Based on these haemodynamic results, management was changed in 12 patients (28%): 5 underwent percutaneous mitral balloon commissurotomy and 7 received intensive medical treatment. CONCLUSIONS: The present study demonstrates that haemodynamic response during dobutamine stress echocardiography correlates with LA fractional shortening in patients with MS. The evaluation of left atrial function at rest in patients with ambiguous symptoms and mild mitral stenosis may be useful in clinical decision making. Atrial dysfunction at rest may predict the haemodynamic response during stress echo in these patients.
Adrenergic beta-Agonists↗
Effects of pacing-induced and balloon coronary occlusion ischemia on left atrial function in patients with coronary artery disease.
OBJECTIVES: The aim of this study was to compare left atrial (LA) function in 16 patients with distal left anterior descending (LAD) and in 16 patients with proximal left circumflex (LCx) coronary artery stenosis at rest and immediately after pacing-induced tachycardia (LAD-pacing [P] and LCx-P) or coronary occlusion (LAD-CO and LCx-CO). BACKGROUND: During left ventricular (LV) ischemia, compensatory augmentation of LA contraction enhances LV filling and performance. The left atrium is supplied predominantly by branches arising from the LCx. Therefore, we hypothesized that one mechanism for the loss of atrial contraction may be ischemic LA dysfunction. METHODS: Left ventricular and LA pressure-area relations were derived from simultaneous double-tip micromanometer pressure recordings and automatic boundary detection echocardiograms. RESULTS: Immediately after pacing or after coronary occlusion, LV end-diastolic pressure, LV relaxation, LA mean pressure and LV stiffness significantly increased in all patients. However, the area of the A loop of the LA pressure-area relation, representing the LA pump function, significantly decreased in groups LCx-P and LCx-CO (from 14+/-3 to 9+/-2, and from 16+/-4 to 9+/-2 mm Hg.cm2, respectively, p < 0.05), whereas it increased in groups LAD-P and LAD-CO (from 12+/-3 to 54+/-10, and from 16+/-3 to 49+/-8 mm Hg.cm2, respectively, p < 0.001). CONCLUSIONS: In patients with LAD stenosis, LV supply or demand ischemia is associated with enhanced LA pump function. However, in patients with proximal LCx stenosis who develop the same type and degree of ischemia, LA branches might have been affected, rendering the LA ischemic and unable to increase its booster pump function.
Angioplasty, Balloon, Coronary↗
Effects of digoxin on left atrial function in heart failure.
OBJECTIVE: To investigate the effects of digoxin on left atrial (LA) function in patients with congestive heart failure and dilated left atria. PATIENTS: 30 patients with enlarged left atrium (maximum LA diameter > 4 mm) caused by heart failure (New York Heart Association functional class III or IV) were studied before and after treatment with digoxin (0.25 mg orally for 12 days). Digoxin was also administered to 30 normal participants who served as controls. MAIN OUTCOME MEASURES: LA active (AEF) and passive emptying fractions (PEF), reservoir fraction (RF), kinetic energy (KE), and mean velocity of circumferential atrial fibre shortening (Vcf) were calculated from echocardiographic measurements of LA volumes and transmitral Doppler flow velocities at baseline and on the third, sixth, eighth, and 12th day after digoxin administration. RESULTS: LA AEF, PEF, RF, KE, and Vcf were significantly lower in patients than in controls (p < 0.001). LA AEF, PEF, RF, KE, and Vcf increased significantly both in patients and controls after digoxin administration (p < 0.001). This increase was greater in patients than in controls (p < 0.001). KE was linearly correlated with LA volume at the onset of atrial systole in all participants. The slope and the intercept of this relation were significantly increased after digoxin both in patients and in controls (p < 0.001). CONCLUSIONS: LA performance is impaired in patients with heart failure. Dilated atria manifest atrial failure. Digoxin improves LA performance and LA contractility both in dilated and in normal atria. The effects of digoxin on LA contractility are augmented in the failing atria compared with the normal atria.
Adult↗
Increasing degrees of left ventricular filling impairment modulate left atrial function in humans.
We sought to investigate the changes in atrial reservoir, pump, and conduit functions that are associated with increasing degrees of left ventricular filling impairment. In 13 patients with an impaired relaxation type of filling and in 15 with restrictive patterns, the left atrial volume curve was constructed combining Doppler and 2-dimensional echocardiography. Nine normal subjects served as controls. Left atrial reservoir (defined as [maximum - minimum atrial volume] minus the amount of blood flow reversal in the pulmonary veins with atrial contraction), pump (defined by the volume of blood that enters the ventricle with atrial contraction), and conduit functions (defined as left ventricular filling volume - [left atrial reservoir plus pump volume]) were computed and each expressed as a percentage of ventricular filling volume. The atrial reservoir function was higher in the impaired relaxation group than in normal subjects (49+/-8% vs 38+/-8%, p <0.01) but markedly lower in the restrictive group (27+/-8%, p <0.05). The reverse was true for conduit function, exaggerated in restrictive group (54+/-12% vs 36+/-11% in normal subjects, p <0.01) but minimized in patients with an impaired relaxation type of filling (14+/-9%, p <0.001). The atrial pump contributed 19+/-6% of ventricular filling volume in restrictives, 26+/-3% in normals (p <0.01), and 38+/-4% (p <0.001) in the impaired relaxation group. We conclude that increased atrial response to early-stage left ventricular filling impairment is characterized by augmented reservoir and pump functions, according to a Starling mechanism, which becomes hardly effective at end-stage ventricular dysfunction when the limits of the atrial preload reserve are reached. At this stage, conduit in the atrium takes precedence.
Adult↗
Left atrial function as a reliable predictor of exercise capacity in patients with recent myocardial infarction.
STUDY OBJECTIVE: To examine the relation between left atrial (LA) function and exercise performance. DESIGN AND SETTING: Retrospective study at a referral cardiopulmonary exercise laboratory in a university hospital. PATIENTS: Forty-one patients with recent myocardial infarction. INTERVENTIONS: M-mode echocardiography and cardiopulmonary exercise testing combined with radionuclide ventriculography. MEASUREMENTS AND RESULTS: Hemodynamic measurements were obtained at rest and peak exercise. LA fractional shortening at rest was used as an index of global LA function. LA fractional shortening had fair correlations with peak oxygen consumption (r=0.67, p<0.01) and exercise duration (r=0.71, p<0.01). Although there were no significant relations between LA fractional shortening and hemodynamic measurements at rest, LA fractional shortening was positively related to peak cardiac output (r=0.61, p<0.01) and peak stroke volume (r=0.57, p<0.01), and negatively related to peak pulmonary arterial wedge pressure (r=-0.44, p<0.05). In addition, LA fractional shortening correlated significantly with an increase in left ventricular (LV) end-diastolic volume from rest to peak exercise (r=0.48, p<0.02), but did not correlate with the changes in ejection fraction and end-systolic volume during exercise. An increase in LV end-diastolic volume during exercise was significantly related to peak oxygen consumption (r=0.46, p<0.02), peak cardiac output (r=0.60, p<0.01), and peak stroke volume (r=0.53, p<0.01), whereas the changes in ejection fraction and end-systolic volume during exercise were not related to these indexes. CONCLUSIONS: Exercise capacity and LV performance during exercise were mainly dependent on LV diastolic filling rather than systolic contraction during exercise. LA fractional shortening at rest reflected LV diastolic filling during exercise and, therefore, predicted cardiac output and stroke volume responses to exercise and exercise capacity in patients with recent myocardial infarction.
Adult↗
Quantitative regional analysis of left atrial function by Doppler tissue imaging-derived parameters discriminates patients with posterior and anterior myocardial infarction.
BACKGROUND: Doppler tissue imaging can now be used for the assessment of left atrial (LA) function. LA function was evaluated by this technique in a group of patients hospitalized for acute myocardial infarction and in a control population. METHODS: Patients were all prospectively imaged with a scanner. To study the LA, a region of interest was located in the proximal part of the lateral and septal LA walls. Doppler tissue imaging, tissue tracking, strain, and delays were recorded. RESULTS: In all, 12 patients with posterior (age 54 +/- 9 years) and 13 with anterior (age 64 +/- 16 years) acute myocardial infarction, along with 16 control patients (age 54 +/- 9 years), were analyzed. Early diastolic septal velocity was found to be the best parameter for discriminating among the 3 groups. Peak strain was also relevant and did not correlate with left ventricular function. CONCLUSIONS: LA is accessible to Doppler tissue imaging analysis. Strain can quantify LA function relatively independently of left ventricular function, and may provide new insights on LA function.
Aged↗
Influence of isoflurane on left atrial function in dogs with pacing-induced cardiomyopathy: evaluation with pressure-volume relationships.
OBJECTIVE: The actions of volatile anesthetics on left ventricular (LV) function in normal and failing hearts have been previously evaluated, but the effects of these agents on left atrial (LA) function in the presence of LV dysfunction are unknown. The hypothesis was tested that isoflurane alters LA mechanics evaluated with pressure-volume relations. DESIGN: Prospective. SETTING: Laboratory. PARTICIPANTS: Barbiturate-anesthetized dogs (n = 8) were instrumented for measurement of aortic, LA, and LV pressures (micromanometers), and LA volume (epicardial orthogonal sonomicrometers) after 3 weeks of rapid ventricular pacing (220 beats/min). INTERVENTIONS: LA myocardial contractility (E(es)) was assessed with end-systolic pressure-volume relations. LA stroke work and reservoir function were assessed by A and V loop area, respectively, from the steady-state pressure-volume diagram. LA-LV coupling was determined by the ratio of E(es) to LV elastance (E(LV)). Dogs received 0.6, 0.9, and 1.2 minimum alveolar concentration isoflurane in a random manner, and LA function was determined after a 20-minute equilibration at each dose. MEASUREMENTS AND MAIN RESULTS: Isoflurane significantly (p < 0.05) decreased heart rate, mean arterial pressure, LV end-systolic pressure, and LV +dP/dt(max). Isoflurane produced dose-related reductions in E(es) and E(es)/E(LV). Declines in LA stroke work, emptying fraction, reservoir volume, V loop area, and the active LA contribution to LV filling also occurred. CONCLUSIONS: The results indicate that isoflurane depresses LA myocardial contractility, impairs LA-LV coupling, and reduces active LA contribution to LV filling in dogs with pacing-induced cardiomyopathy. The impact of isoflurane on LA function in the presence of LV dysfunction has profound effects on cardiac performance.
Anesthetics, Inhalation↗
[The influence of electrical cardioversion on left ventricular systolic function, left atrial size, ANP levels and enzymatic activity of CPK and CD-MB in serum of patients with paroxysmal atrial fibrillation].
OBJECTIVE: To estimate the influence of electrical cardioversion on the left ventricular systolic function, left atrial size, the plasma activity of creatinine phosphokinase (CPK) and its myocardial fraction (CK-MB) and plasma level of atrial natriuretic peptide (ANP) in patients with paroxysmal atrial fibrillation caused by coronary artery disease, hypertension or mitral valve disease. PATIENTS: The study underwent 36 patients with paroxysmal atrial fibrillation of mean duration 24.5 hours in which sinus rhythm was restored by electrical cardioversion. METHODS: Plasma activity of creatinine phosphokinase (CPK) and its myocardial fraction (CK-MB), plasma level of atrial natriuretic peptide (ANP) and echocardiographic examination were obtained before and 24 hour after electrical cardioversion. During echocardiographic examination were measured left ventricular end diastolic diameter (LVEDD), left ventricular ejection fraction (LVEF), left atrial size (LA) and early diastolic velocity(E) and velocity with atrial contraction (A) of left ventricular inflow. Electrical cardioversion was initiated with impulse of 100 J. If it failed to convert atrial fibrillation to sinus rhythm next impulse of 200 J and 360 J were consequently applied. RESULTS: In all subgroups of patients formed dependently on a number of electrical shocks, 24 hour after cardioversion significant increase in left ventricular ejection fraction (LVEF) and decrease in plasma level of ANP were noted. In subgroup of patients treated with 1 (100 J) and 2 (100 + 200 J) impulse significant decrease in left atrial size was found out. The increase in plasma activity of creatinine phosphokinase (CPK) and its myocardial fraction (CK-MB) was confined to the subgroup treated with 3 (100 + 200 + 360 J) impulses. No changes in left ventricular end diastolic diameter (LVEDD) and early velocity (E) of left ventricular inflow 24 hours after cardioversion were observed. In all patients electrical cardioversion brought about the appearance of atrial wave of left ventricular inflow. No differences in estimated parameters between patients with coronary artery disease, hypertension and mitral valve disease were observed. Significant positive correlation between plasma level of ANP and left atrial size before (r = 0.69, p < 0.001) and after cardioversion (r = 0.68, p < 0.0001) were found. CONCLUSIONS: Restoration of the sinus rhythm in patients with paroxysmal atrial fibrillation leads to the increase in left ventricular ejection fraction (LVEF) and to the decrease in left atrial size (LA) and the plasma level of atrial natriuretic peptide. Left atrial size and plasma level of ANP are related. The cardioversion with impulses of high energy increases the plasma activity of creatinine phosphokinase and its myocardial fraction.
Adult↗
Effects of balloon mitral valvuloplasty on left atrial function in mitral stenosis as assessed by pressure-area relation.
OBJECTIVES: This study sought to investigate the changes induced on the pressure-area relation of the left atrium in patients with mitral stenosis after percutaneous balloon mitral valvuloplasty. BACKGROUND: Left atrial (LA) function is influenced by changes in LA afterload. The latter is increased in mitral stenosis as a result of increased resistance to blood flow imposed by the stenotic mitral valve. METHODS: We studied the effects of acute alterations of LA afterload induced by retrograde nontransseptal balloon mitral valvuloplasty (RNBMV) on LA function in patients with mitral stenosis. LA pressure-area relations were obtained in 15 patients with mitral stenosis (8 with sinus rhythm, 7 with atrial fibrillation) before and after valvuloplasty, as well as in 15 normal subjects. LA pressure was recorded by a catheter-tipped micromanometer introduced retrogradely into the left atrium while LA area was recorded simultaneously using acoustic quantification. The areas of the A and V loops of the pressure-area relation as well as the LA chamber stiffness constant were calculated. RESULTS: Balloon valvuloplasty resulted in a significant increase in mitral valve area (p < 0.001) and a substantial reduction of the mean transmitral pressure gradient (p < 0.001) and mean LA pressure (p < 0.001). The area of the A loop in patients with sinus rhythm and the area of the V loop in those with atrial fibrillation increased significantly after completion of the procedure (p < 0.001). Furthermore, LA stiffness decreased in both groups. CONCLUSIONS: After RNBMV, there is a significant increase in LA pump function in patients with sinus rhythm, a significant increase in LA reservoir function in patients with atrial fibrillation and a significant reduction in LA stiffness in all patients. Marked alterations of the configuration of the LA pressure-area relation occur immediately after successful RNBMV in patients with mitral stenosis.
Adult↗
Measurement of normal left atrial function with gated radionuclide angiography.
A method is described for measuring relative left atrial volume changes with gated radionuclide angiography, using an approximate computer-generated functional image to locate the atrial region of interest. M mode echocardiographic measurements of left atrial and left ventricular distances from the chest wall allowed calculation of a correction factor for the differential attenuation of atrial and ventricular photons. Background-corrected left atrial time-activity curves obtained from normal subjects exhibited excellent temporal resolution and were used to identify and quantitate the reservoir and contractile phases of left atrial volume change. In 20 normal subjects, the mean (+/- standard deviation) value for left atrial fractional emptying was 0.39 +/- 0.07. Expressed as fractions of the left ventricular stroke volume, mean values of the specific phases of atrial volume change were (1) reservoir volume 0.25 +/- 0.09, (2) contractile volume 0.29 +/- 0.10, and (3) conduit volume 0.46 +/- 0.12.
Adult↗