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PubMed1995

Left atrial spontaneous echo contrast in patients with rheumatic mitral valve disease in sinus rhythm. Implication of an altered left atrial appendage function in its formation.

Thirty-nine patients who had rheumatic mitral valve disease in sinus rhythm were studied to compare echocardiographic and hemodynamic characteristics between those with and without left atrial (LA) spontaneous echo contrast. Patients were divided into two groups according to the presence (group 1, n = 17) or absence (group 2, n = 22) of the echo contrast. Transthoracic echocardiography and transesophageal echocardiography were performed in all patients within 1 week of cardiac catheterization study. Group 1 patients (5 men and 12 women; mean age, 47.7 +/- 13.1 years) showed smaller mitral valve area, greater transmitral valve pressure gradient, and absence of moderate to severe mitral regurgitation compared with group 2 patients (7 men and 15 women; mean age, 47.8 +/- 14.3 years). There was no significant difference in LA dimension, left ventricular end-systolic and end-diastolic dimensions, or in left ventricular ejection fraction between the two groups of patients. Left atrial appendage function was studied with Doppler in 26 patients. Patients (n = 10) with LA spontaneous echo contrast had significantly lower LA appendage ejection fraction (20.34 +/- 10.76% vs 34.16 +/- 13.13%; p < 0.05) and lower LA appendage peak emptying velocity (0.17 +/- 0.09 m/s vs 0.27 +/- 0.12 m/s; p < 0.05) than those (n = 16) without echo contrast. It is concluded that obstruction to mitral flow and altered LA appendage contractile function, not the LA size, are likely to be more important factors for the development of LA and LA appendage spontaneous echo contrast in patients with rheumatic mitral valve disease (predominant mitral stenosis) who are in sinus rhythm. These findings further substantiate that blood stasis in the LA cavity and the LA appendage is the mechanism fundamental to the formation of such spontaneous echo contrast.

Adult↗
PubMed1983

Function of atrial preferential conduction routes under normal and abnormal conditions.

The function of the atrial preferential conduction routes was examined by the microelectrode technique under normal and abnormal conditions in excised rabbit hearts. The sinus impulse during normal conditions traveled faster along the left and the right branch of the crista terminalis (anterior and posterior preferential routes, respectively) in the atrium toward the A-V node. Cutting of either route caused a delay of the impulse arrival in the zone beyond the lesion. The internodal conduction time was delayed 12 msec upon cutting of the posterior route, but there was no conduction delay after cutting the anterior route. This indicates that the posterior path is the dominant conduction route under normal conditions. When both routes were cut, the internodal conduction time was delayed 33 msec from the control value. During abnormal conditions, an ectopic pacemaker was found to occur mainly in the regions of two routes, as well as in the coronary sinus region. The cutting of either route, combined with the application of acetylcholine or high external K+, resulted in easier provocation of re-entrant arrhythmias in response to premature-stimuli than before the cutting.

Animals↗
PubMed1997

[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↗
PubMed1995

Aggravation of postcardioversion atrial dysfunction by sotalol.

OBJECTIVES: This study determined the effect of sotalol on atrial function after electrical cardioversion of atrial fibrillation. BACKGROUND: After electrical cardioversion of atrial fibrillation, the Doppler mitral A wave is often diminished, representing impaired atrial contractile function. Sotalol is an effective atrial antiarrhythmic drug with class III and beta-adrenergic blocking properties. Although the negative inotropic effect of sotalol on the ventricle is minimal in patients with normal ventricular function, it may manifest negative inotropy when ventricular function is impaired. We postulated that after cardioversion, when intrinsic atrial function is impaired, sotalol may have an adverse effect on the atrium. METHODS: Thirty-seven patients enrolled in a randomized, double-blind study of sotalol for maintenance of sinus rhythm were studied by quantitative Doppler echocardiography within 24 h of electrical cardioversion and, for those still in sinus rhythm, again at 1 month. Doppler variables (E and A wave velocities and integrals) in patients receiving sotalol were compared with those in patients receiving placebo. RESULTS: After electrical cardioversion, peak A wave velocity and A wave time-velocity integral in the 20 patients receiving placebo were reduced compared with normal values. In the 17 patients receiving sotalol (median dose 320 mg twice daily) these variables were further reduced (mean [+/- SD] peak A wave velocity 19.4 +/- 5.5 vs. 38.4 +/- 14.7 cm/s, p < 0.001 and mean A wave time-velocity integral 1.7 +/- 0.6 vs. 3.4 +/- 1.4 cm, p < 0.001, in sotalol- vs. placebo-treated patients, respectively). Early diastolic filling (E wave variables) did not differ between sotalol- and placebo-treated groups. At 1 month, five sotalol- and six placebo-treated patients remained in sinus rhythm, and A wave variables had increased for the whole group, with a greater increase in sotalol-treated patients. CONCLUSIONS: After electrical cardioversion, when atrial stunning is prominent, sotalol has a negative atrial inotropic effect. This effect may be temporary, as suggested by resolution at 1 month. Negative inotropic effects of antiarrhythmic drugs on the atrium should be considered in assessing Doppler variables of left ventricular filling.

Adult↗
PubMed1999

Left atrial systolic function is depressed in idiopathic and preserved in ischemic dilated cardiomyopathy.

BACKGROUND: Left atrial systolic dysfunction, unexplained by altered loading conditions, has been reported in idiopathic dilated cardiomyopathy suggesting left atrial involvement in the myopathic process. MATERIALS AND METHODS: Seventeen patients with idiopathic dilated cardiomyopathy, 16 with ischemic dilated cardiomyopathy and 18 normal controls were studied with transthoracic echocardiography and cardiac catheterization. Transmitral diastolic flow was evaluated with pulsed Doppler. Left atrial volume (cm3/m2) at mitral valve opening (maximal, Vmax.), onset of atrial systole (P wave of the electrocardiogram, Vp), and mitral valve closure (minimal, Vmin. ) was determined with two-dimensional echocardiography using the biplane area-length method. The left atrial active emptying fraction (ACTEF = [Vp-Vmin.] x 100/Vp) served as an index of systolic function. RESULTS: The peak early diastolic transmitral flow velocity (cm/sec) was similar in the three groups (idiopathic: 60 +/- 16, ischemic: 58 +/- 20, control: 56 +/- 22; P = NS), whereas the late diastolic transmitral flow velocity was lower but not significantly different in idiopathic compared to ischemic cardiomyopathy, and in both was lower than control (26 +/- 12 vs. 34 +/- 13 vs. 44 +/- 14, respectively; P < 0.05). Vmax. and Vp were similar in idiopathic and ischemic cardiomyopathy and greater than control (44.6 +/- 13.6 vs. 48.2 +/- 18.3 vs. 26.9 +/- 6.2; P < 0.05, and 34.6 +/- 13.4 vs. 30.8 +/- 10.9 vs. 16.7 +/- 3.7, respectively; P < 0.05). ACTEF was lower in idiopathic than in ischemic cardiomyopathy and in the latter it was similar to control (18 +/- 10% vs. 32 +/- 10% vs. 36 +/- 10%, respectively; P < 0.05). Moreover, ACTEF was inversely related to left atrial tension at end-of atrial systole both in idiopathic and in ischemic cardiomyopathy (r2 = 0.52, P = 0.001 and r2 = 0.57, P = 0.0007, respectively). However, at any given level of left atrial tension at end of atrial systole, ACTEF was lower in idiopathic than ischemic cardiomyopathy. CONCLUSION: Left atrial systolic function is depressed in idiopathic and preserved in ischemic dilated cardiomyopathy despite similar left atrial loading conditions. This finding suggests left atrial myopathy in the former, and may be related to the differences in the response to medical treatment and clinical outcome observed between the two conditions.

Atrial Function, Left↗
PubMed2001

Assessment of LV systolic function in atrial fibrillation using an index of preceding cardiac cycles.

The clinical assessment of left ventricular (LV) systolic function during atrial fibrillation (AF) is unreliable and difficult because of beat-to-beat variability. We evaluated an index for the estimation of LV systolic function in AF that is based on the relationship between the preceding (R-R1) and prepreceding (R-R2) R-R intervals. LV Doppler stroke volume (SV), ejection fraction (EF), peak aortic flow rate (AoF) and the maximum value of the first derivative of the LV pressure curve (dP/dt(max)) were evaluated in 13 healthy open-chest dogs during triggered AF. All parameters showed a significantly strong positive linear relationship with the ratio of R-R1/R-R2 (r = 0.65, 0.74, 0.75, and 0.70 for SV, EF, AoF, and dP/dt(max), respectively). The calculated value of LV systolic parameters at R-R1/R-R2 = 1 in the linear regression line showed a good relationship and an agreement with the measured average value of the parameter over all cardiac cycles (SV, 12.1 vs. 12.8 ml; EF, 49.6 vs. 51.2%; AoF, 1.37 vs. 1.48 l/min; and dP/dt(max), 2,323 vs. 2,454 mmHg/s). Using the LV systolic parameters estimated at R-R1/R-R2 = 1 in the linear regression line allows the LV contractile function to be accurately and reproducibly evaluated during AF and obviates the less-reliable process of averaging multiple cardiac cycles.

Animals↗
PubMed2000

Prognostic value of left atrial appendage function in patients with dilated cardiomyopathy.

The purpose of the present study was to determine whether parameters of left atrial appendage (LAA) function, assessed by transesophageal echocardiography (TEE), could predict the clinical outcome in patients with dilated cardiomyopathy (DCM). Fifty-five patients (20 had ischemic cardiomyopathy; mean age, 56+/-14 years) who underwent TEE to evaluate LAA function from 1992 to 1996 were studied. After a mean follow-up period of 34+/-13 months, 16 patients died; the cause was cardiac in 14 and noncardiac in 2. Patients who died of cardiac cause had a lower LAA emptying velocity than survivors (38+/-18 vs 54+/-18 cm/s, p=0.01). There were, however, no significant differences between survivors and nonsurvivors with regard to the maximal LAA area (4.3+/-1.3 vs 4.5+/-0.9 cm2, p=0.55), minimal LAA area (2.4+/-1.1 vs 2.9+1.1 cm2, p=0.13), and LAA ejection fraction (46+/-16 vs 36+/-18%, p=0.05). On the Cox proportional hazards model analysis, LAA emptying velocity <50 cm/s (chi-square 5.9, p=0.02), LAA ejection fraction <43% (chi-square 5.6, p=0.02), female gender (chi-square 5.2, p=0.02), pulmonary artery wedge pressure > or =14 mmHg (chi-square 4.8, p=0.03), E/A ratio > or =1.3 (chi-square 4.6, p=0.03), deceleration time <148 ms (chi-square 4.6, p=0.03), and cardiothoracic ratio > or =54% (chi-square 4.3, p=0.04) were significantly related to cardiac death. The stepwise multivariate analysis revealed that LAA emptying velocity (chi-square 6.1, p=0.01) and gender (chi-square 5.4, p=0.02) were the independent predictors for outcome. In conclusion, the parameters of LAA function may be useful predictors of the clinical outcome in patients with DCM.

Adult↗
PubMed1998

Left atrial appendage function in mitral stenosis: is a group in sinus rhythm at risk of thromboembolism?

OBJECTIVE: To study the left atrial appendage (LAA) function and potential for embolization in severe mitral stenosis (MS). BACKGROUND: Patients with MS and atrial fibrillation or in sinus rhythm develop systemic emboli. LAA function has not been well studied in sinus rhythm. METHODS: Forty consecutive patients with MS (valve area < or =0.7 cm2/m2) were studied. LAA ejection fraction and peak emptying velocity were measured along with other data. RESULTS: Patients were subgrouped according to LAA Doppler flow pattern. Group I (n=13) in sinus rhythm had biphasic high velocity > or =25 cm/s. Group II (n=13) in sinus rhythm had biphasic low velocity <25 cm/s. Group III (n=14) in atrial fibrillation had multiphasic irregular flow <25 cm/s or no definite flow. The LAA ejection fraction and peak emptying velocity were strikingly different in all groups. They were lower in group II when compared to group I. Group II had intermediate risk for thromboembolism compared to Group I and III as judged by systemic embolization, spontaneous echo contrast, thrombus in left atrium and LAA. CONCLUSION: A subset of mitral stenosis in sinus rhythm at increased risk of embolization can be suspected by Doppler transesophageal echocardiographic LAA flow profile.

Adolescent↗
PubMed2001

Effects of rhythm regularization and rate control in improving left ventricular function in atrial fibrillation patients undergoing atrioventricular nodal ablation.

OBJECTIVES: To assess the relative contributions of rate control and rhythm regularization to left ventricular function in atrial fibrillation (AF) patients undergoing atrioventricular nodal ablation. This was performed by assessing the effect of ventricular rhythm regularization on left ventricular function during AF, and the effect of varying heart rate on left ventricular function after ablation. PATIENTS AND METHODS: Eleven patients with continuous AF and V/VI-R pacemakers undergoing therapeutic atrioventricular nodal ablation were studied. Preablation patients underwent two 30 min observation periods in a randomized, blinded fashion during which they were either in baseline AF (pacer set to default V/VI 50/min) or being paced using a rhythm stabilizing algorithm (RSA) designed to regularize rhythm without changing baseline ventricular rate. Six weeks after ablation, patients were again observed during the two following 30 min periods: pacing at a low clinically indicated rate (69+/-9 beats/min), and pacing at the rapid, mean preablation rate. During all observation periods, left ventricular function was measured continuously using a nuclear vest that provided validated measures of heart rate, ejection fraction, and normalized end-systolic volume (ESV) and end-diastolic (EDV) volume. RESULTS: Before ablation, RSA successfully regularized rhythm, decreasing the coefficient of variation of interbeat intervals 20+/-5% to 10+/-4% (P<0.001). The heart rate with RSA (105+/-19 beats/min) was not significantly different from the baseline AF rate (102+/-21 beats/min). Increased rhythm regularity achieved by RSA significantly improved left ventricular function, decreasing ESV from 62+/-12 units to 57+/-11 units (P=0.03), and increasing the ejection fraction from 31+/-11% to 36+/-11% (P=0.03). After ablation, at the clinically indicated low pacing rate of 69+/-9 beats/min, a much greater improvement in ejection fraction was observed, increasing to 44+/-13% (P=0.005 compared with preablation). However, rapid regular pacing at the mean preablation rate of 110+/-18 beats/min eradicated this improvement, decreasing the ejection fraction to 31+/-8% (P=0.003), and increasing ESV from 53+/-13 units to 62+/-8 units (P=0.006). CONCLUSIONS: Rhythm regularity achieved by a regularizing pacing algorithm can significantly, albeit modestly, improve left ventricular function in AF. However, more marked improvements in left ventricular function seen after ablation are primarily due to rate reduction alone.

Aged↗
PubMed1994

Left atrial appendage function determined by transesophageal echocardiography in patients with rheumatic mitral valve disease.

Left atrial thrombi have been considered to be the major source of systemic arterial embolization in patients with rheumatic mitral valve disease. Almost half of the left atrial thrombi are found in the left atrial appendage (LAA). To investigate LAA size and LAA contractile function in patients with rheumatic mitral valve disease, transesophageal echocardiographic and Doppler studies were performed in 61 patients. Among them, 46 patients were in atrial fibrillation (group 1), while the other 15 were in sinus rhythm (group 2). Thirty-six patients with nonrheumatic atrial fibrillation were chosen as control to group 1. Another 22 patients with various cardiovascular diseases and sinus rhythm served as control to group 2. When compared to the patients with nonrheumatic atrial fibrillation (control group), group 1 patients tended to have a larger LAA maximal area (9.7 +/- 5.2 vs. 5.9 +/- 2.8 cm2; p < 0.001). LAA ejection fraction and LAA peak emptying velocity were also lower. A significantly higher incidence of LAA spontaneous echo contrast (SEC) and thrombus formation was also found in these patients. Group 2 patients were also found to have a larger LAA maximal area when compared to the control group (8.8 +/- 3.7 vs. 5.2 +/- 3.0 cm2; p < 0.001). LAA ejection fraction and LAA peak emptying velocity were lower in this group, too. A higher incidence of LAA SEC formation was found in these patients with rheumatic mitral valve disease (4/15 vs. 0/22; p = 0.021). There was no significant difference, however, in LAA thrombus formation between group 2 and its control group (1/15 vs. 1/22; p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Stratification of thromboembolic risk of atrial fibrillation by transthoracic echocardiography and transesophageal echocardiography: the relative role of left atrial appendage function, mitral valve disease, and spontaneous echocardiographic contrast.

The role of transesophageal echocardiography (TEE) in thromboembolic risk stratification in atrial fibrillation (AF) has not been established. Left atrial appendage contractile dysfunction in patients with AF predisposes to thrombus formation. The extent of blood stasis and propensity for thrombus can be assessed during TEE by measurement of the peak Doppler velocity of blood outflow from the appendage. Spontaneous echocardiographic contrast (SEC) is a swirling pattern of blood echogenicity that may be detected by TEE in the left atrium in patients with AF. The presence of SEC reflects left atrial blood stasis and a prothrombotic state. SEC is associated with an increased risk of systemic thromboembolic events. Parameters derived from TEE may provide additional prognostic data to clinical history and transthoracic echocardiography in thromboembolic risk stratification in AF.

Atrial Fibrillation↗
PubMed1987

Ventricular function after atrial cardioplegia.

Continuous retrograde coronary sinus cardioplegia (CSCP) has previously been carefully evaluated experimentally and shown to be efficacious during ischemia, even in the presence of coronary lesions and in the hypertrophied state. A new technique of retrograde cardioplegia delivery through the right atrium, using right ventricular distension and pressures of 60 mm Hg, has recently been described with excellent clinical results. This study was designed to specifically examine right ventricular function after atrial cardioplegia and acute passive right ventricular distension. CSCP (n = 10) was compared with cardioplegia delivered through the right atrium both continuously (n = 10) and intermittently (n = 8). When ventricular function was examined with the use of the load-independent relationship of stroke work vs end-diastolic length, there was a profound deterioration of right ventricular function in both atrial cardioplegia groups (44% and 37% of control values, respectively) after 1 hr of reperfusion. In contrast, biventricular function was fully preserved in the CSCP group 1 hr after reperfusion. Left ventricular function measured at the end of reperfusion was preserved in all three groups. Right ventricular ATP levels were slightly but significantly depressed in all groups and in the atrial cardioplegia groups, this metabolic change was also seen in the left ventricle. These metabolic and hemodynamic data may reflect the inability of atrial cardioplegia to cool the myocardium below 16 degrees C. Postoperative right ventricular dysfunction may be more common than has been previously thought when atrial cardioplegia is used, particularly in the absence of topical cooling.

Adenine Nucleotides↗
PubMed1999

Decreased left atrial appendage function is an important predictor of elevated left ventricular filling pressure in patients with congestive heart failure.

OBJECTIVE: The aim of this study was to investigate whether left atrial (LA) appendage function, as indicated by LA appendage blood flow velocities and its ejection fraction, could identify elevated left ventricular filling pressure in patients with chronic congestive heart failure. METHODS: Using transesophageal echocardiography, adequate pulsed Doppler LA appendage active emptying and filling velocities could be recorded in 25 consecutive patients (16 men and 9 women, aged 57+/-10 years) with chronic congestive heart failure (symptom duration > or =1 year). LA appendage ejection fraction calculated as (LA appendage maximal area)-(LA appendage minimal area)/(LA appendage maximal area) x 100 was also determined in these patients. Left ventricular end-diastolic pressure was recorded during cardiac catheterization performed within 24 h of echocardiographic study. RESULTS: Left ventricular end-diastolic pressure was 2 to 47 mm Hg. There were close negative correlations of LA appendage emptying velocity (r=-0.508; P<0.01), filling velocity (r=-0.429; P<0.05) and LA appendage ejection fraction (r=-0.523; P<0.005) with left ventricular end-diastolic pressure. LA appendage active emptying velocity <30 cm/s predicted left ventricular end-diastolic pressure >25 mm Hg with a sensitivity of 72.7%, a specificity of 92.9% and a positive and negative predictive value of 88.9 and 81.3%. CONCLUSIONS: The findings suggest that measurement of LA appendage blood flow velocities and contractile function by transesophageal echocardiography can be used to predict elevated left ventricular filling pressure in patients with congestive heart failure.

Atrial Function, Left↗
PubMed1996

Pulmonary edema following electrical cardioversion of atrial fibrillation.

A 61-year-old man with hypertrophic cardiomyopathy developed acute pulmonary edema 29 h following cardioversion of chronic atrial fibrillation to sinus rhythm. Doppler echocardiographic evaluation of atrial function showed return of right atrial contraction but absent left atrial systole. This has not been reported previously in a case of postcardioversion pulmonary edema.

Atrial Fibrillation↗
PubMed1991

Allosteric modulation by ATP of the bovine adrenal natriuretic factor R1 receptor functions.

Atrial natriuretic factor (ANF-R1) receptor is a 130-kDa protein that contains a cytoplasmic guanylate cyclase domain. We report that ATP interacts in an allosteric manner with the ANF-R1 receptor, resulting in reduced ANF binding and enhanced ANF-stimulated guanylate cyclase activity. The modulatory properties of various nucleotides indicate a preference for the adenine family with a rank order of potency of ATP greater than App(NH)p greater than or equal to ADP greater than or equal to AMP while cyclic and guanine nucleotides except GTP are inactive. The negative modulation by ATP of ANF binding is specific for the ANF-R1 receptor subtype since the amount of ANF bound by the guanylate cyclase uncoupled ANF-R2 subtype is increased in the presence of ATP. Furthermore, the effects of ATP on ANF-R1 receptor binding function are still observed with the affinity-purified ANF-R1 receptor, suggesting an allosteric binding site for ATP on the ANF-R1 receptor. In intact membranes, limited proteolysis of the ANF-R1 receptor with trypsin dose-dependently prevents the ATP-induced decrease in ANF binding concomitantly with the formation of a membrane-associated ANF-binding fragment of 70 kDa. These results confirm the direct modulatory role of ATP on hormone binding activity of ANF-R1 receptor and suggest that the nucleotide regulatory binding site is located in the intracellular domain vicinal to the protease-sensitive region.

Adenosine Triphosphate↗
PubMed2002

[The relationship of the left atrial spontaneous echo contrast integrated backscatter with left atrial appendix function and tissue doppler characteristics].

OBJECTIVE: Integrated backscatter (IBS) is an objective method to measure spontaneous echo contrast (SEC) quantitatively. The purpose of this study was to investigate the relationship between the quantitative values of left atrial SEC measured by using IBS with its qualitative gradation as well as the left atrial appendix (LAA) functions and LAA tissue Doppler characteristics (TD). METHODS: Thirty-two patients (23 female, 9 male) with various diseases undergoing transesophageal echocardiography (TEE) were included. Mean age was 52 + 13 years. Left atrial SEC was graded as no SEC (n = 12), mild (n = 12) or severe SEC (n = 8) in patients underwent TEE. LAA peak emptying and LAA apical and basal TD velocities were measured. LAA ejection fraction was assessed by standard means. RESULTS: Between no SEC and mild SEC groups, left atrium IBS and LAA apical TD values were found statistically significant. But there were no differences between two groups regarding LAA emptying velocities, LAA ejection fraction values and LAA basal TD values. All of these parameters were found statistically different between severe and mild SEC groups. The left atrial IBS values were found to be correlated positively with the qualitative SEC grade. The left atrial IBS values correlated negatively with LAA emptying, apical TD velocities and LAA ejection fraction values. CONCLUSION: Integrated backscatter provides an objective quantitative measure of SEC that correlates well with LAA apical TD velocities and the other parameters of LAA.

Atrial Appendage↗
PubMed1992

Effect of pharmacological manipulation of endogenous atriopeptin activity on renal function.

Atrial stretch causes the release of atriopeptin (AP, ANF) from preformed vesicular storage sites. The circulating hormone acts on unique receptor sites (containing guanylate cyclase) to release guanosine 3',5'-cyclic monophosphate (cGMP) that mediates the natriuresis and vasodilation and probably the suppression of renin, aldosterone, and vasopressin. The biological effects of atriopeptin are transient because of the rapid inactivation of the circulating hormone (by neutral endopeptidase or clearance receptors) or the second messenger (by cGMP-phosphodiesterase). Heart failure due to chronic cardiac volume overload [aortovenocaval (A-V) fistula] exhibits markedly elevated circulating AP blood levels and urinary cGMP levels, accompanied by induction of ventricular AP gene and protein expression and release. Pharmacological manipulation of endogenous AP, either by inhibiting cGMP phosphodiesterase (i.e., mediator prolongation) or neutral endopeptidase (i.e., prolongation of hormone half-life) in A-V fistula animals results in profound natriuresis and diuresis without hypotension. These pharmacological maneuvers bypass the suppressed renal response to exogenous AP seen in heart failure and provide a rational therapeutic strategy based on our understanding of the underlying physiological and pathological mechanisms.

3',5'-Cyclic-GMP Phosphodiesterases↗