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Serial evaluation of left atrial dimension after cardioversion for atrial fibrillation and relation to atrial function.

The size of the left atrium is usually increased during atrial fibrillation (AF). The aim of the present study was to evaluate changes in left atrial (LA) dimension after cardioversion for AF, and the relation between LA dimension and atrial function. The initial study population included 171 consecutive patients. Patients who had spontaneous cardioversion to sinus rhythm (56 patients) were compared with patients who had random cardio-version with drugs (50 patients) or direct-current (DC) shock (50 patients). Echocardiographic evaluations included LA size and volume. LA passive and active emptying volumes were calculated, and LA function was assessed. Atrial stunning was observed in 18 patients reverted with DC shock and in 7 patients reverted with drugs. The left atrium was dilated in all patients during AF (48 +/- 5 mm). The size of the left atrium decreased after restoration of sinus rhythm in all patients with spontaneous reversion to sinus rhythm, in 73% of patients reverted with drugs, and in 50% of patients reverted with DC shock. The comparison between patients with a normal mechanical atrial function and patients with reduced atrial function showed that a higher atrial ejection force was associated with a more marked reduction in LA size after restoration of sinus rhythm. A relation between LA volumes and atrial ejection force was observed in the group of patients with depressed atrial mechanical function (r = -0.78; p <0.001). The active emptying fraction was lower, although not significantly, in this group, whereas the conduit volume was increased. Thus, a depressed atrial mechanical function after cardioversion for AF was associated with a persistence of LA dilation.

Aged↗

ATP-sensitive potassium channels regulate stimulated ANF secretion in isolated rat heart.

Perfused hearts (n = 127) were exposed to acute hypoxia (10% O2 for 12 or 20 min) or left atrial stretch (increase in atrial pressure) in the presence or absence of 100 mumol/l ATP-sensitive potassium channel blocker (tolbutamide) or openers (pinacidil and diazoxide). Hypoxia alone elicited a prolonged atrial natriuretic factor (ANF) release, peaking at 74% over baseline (P < 0.01); with tolbutamide, ANF secretion peaked at 132% over baseline (P < 0.01). Pinacidil and diazoxide abolished the ANF response to hypoxia (P < 0.01). Atrial stretch alone (1 mmHg) transiently (2 min) increased ANF by 56% (P < 0.05); with tolbutamide, ANF increased transiently by 124% and showed a prolonged increase of 52% (P < 0.05). With tolbutamide, graded stretch (0.5-2.3 mmHg) induced a bell-shaped transient (2-min) increase of ANF release [-3% at 0.5 mmHg, 124% (P < 0.05) at 1.0 mmHg, 80% (P < 0.05) at 1.48 mmHg, and 14% at 2.22 mmHg] and a saturating prolonged ANF response. Tolbutamide increased the ANF response nonsignificantly at lower doses (30 mumol/l) and had no effect at 1 mumol/l. Pinacidil abolished the stretch-induced ANF release. These results suggest that ATP-sensitive potassium channels are extremely potent modulators of stimulated ANF secretion.

Adenosine Triphosphate↗

Utility of B-natriuretic peptide in detecting diastolic dysfunction: comparison with Doppler velocity recordings.

BACKGROUND: Although Doppler echocardiography has been used to identify abnormal left ventricular (LV) diastolic filling dynamics, inherent limitations suggest the need for additional measures of diastolic dysfunction. Because data suggest that B-natriuretic peptide (BNP) partially reflects ventricular pressure, we hypothesized that BNP levels could predict diastolic abnormalities in patients with normal systolic function. METHODS AND RESULTS: We studied 294 patients referred for echocardiography to evaluate ventricular function. Patients with abnormal systolic function were excluded. Cardiologists making the assessment of LV function were blinded to BNP levels. Patients were classified as normal, impaired relaxation, pseudonormal, and restrictivelike filling patterns. Patients diagnosed with evidence of abnormal LV diastolic function (n=119) had a mean BNP concentration of 286 +/- 31 pg/mL; those in the normal LV group (n=175) had a mean BNP concentration of 33 +/- 3 pg/mL. Patients with restrictive like filling patterns on echocardiography had the highest BNP levels (408 +/- 66 pg/mL), and patients with symptoms had higher BNP levels in all diastolic filling patterns. The area under the receiver-operating characteristic curve for BNP to detect any diastolic dysfunction was 0.92 (95% CI, 0.87 to 0.95; P<0.001). A BNP value of 62 pg/mL had a sensitivity of 85%, a specificity of 83%, and an accuracy of 84% for detecting diastolic dysfunction. CONCLUSIONS: A rapid assay for BNP can reliably detect the presence of diastolic abnormalities on echocardiography. In patients with normal systolic function, elevated BNP levels and diastolic filling abnormalities might help to reinforce the diagnosis diastolic dysfunction.

Aged↗

Tertatolol potentiates exercise-induced atrial natriuretic peptide release by increasing atrial diameter in healthy subjects.

To evaluate the contribution of atrial distension and/or adrenergic mechanisms in the regulation of atrial natriuretic peptide (ANP) secretion, plasma immunoreactive ANP, norepinephrine (NE), epinephrine (E), and left atrial diameter were measured at rest, during, and after graded upright standardised bicycle exercise in 8 healthy male subjects after single-dose administration of placebo, tertatolol (5 mg), prazosin (1 mg), or combination of tertatolol (5 mg) and prazosin (1 mg). Systolic and diastolic left atrial diameters were measured before, during, and just after exercise by bidimensional echocardiography. Exercise raised plasma ANP concentrations. This rise was greater on tertatolol alone and tertatolol and prazosin than on placebo or prazosin alone: mean area under the plasma ANP concentration curve increased by 35% on tertatolol alone, 45% on tertatolol and prazosin when compared with placebo (p < 0.01), and by 82 and 94%, respectively, when compared with prazosin alone (p < 0.01). The rise in plasma ANP was greater during the postexercise period: 80% for tertatolol alone, 67% for tertatolol and prazosin when compared with placebo (p < 0.01) and 133 and 115%, respectively, when compared with prazosin alone (p < 0.01). The rise in plasma ANP was accompanied by an increase in both systolic and diastolic atrial diameters which was significantly greater on tertatolol alone and on the tertatolol and prazosin combination than on placebo or prazosin alone (p < 0.001). Beta-blockade alone did not affect plasma catecholamine concentrations but exercise-induced increase in plasma NE was significantly potentiated by prazosin and the prazosin and tertatolol combination, and that of plasma E by the prazosin and tertatolol combination.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗

The effect of patient sex on recurrence of atrial fibrillation following successful direct current cardioversion.

BACKGROUND: The effect of patient sex on recurrence of atrial fibrillation after a successful direct current cardioversion is unknown. METHODS: This prospective study included 773 patients (486 [63%] men and 287 [37%] women) undergoing successful direct current cardioversion of atrial fibrillation between May 2000 and July 2003. Patient characteristics at presentation were recorded. The primary end point was the time between cardioversion and the first documented recurrence of arrhythmia. RESULTS: At presentation, women were older and had a higher prevalence of hypertension and valvular disease compared with men. In addition, women had worse mechanical left atrial appendage function. Arrhythmia recurrence was more prevalent in women (50.0% at 1 year compared with 43.4% in men, and 75.8% at 2 years compared with 67.0% in men; P = .03). On the basis of multivariate analysis, patient sex was a significant predictor of arrhythmia recurrence. There was no significant difference in overall mortality between men and women. CONCLUSIONS: Women were more likely than men to have recurrence of atrial fibrillation after successful direct current cardioversion. Patient sex should be taken into account with other clinical factors when making the decision about cardioversion for atrial fibrillation.

Aged↗

Determinants of atrial fibrillation development in patients with hypertrophic cardiomyopathy.

Predictors of the development of atrial fibrillation (AF) in patients who have hypertrophic cardiomyopathy (HC) have not been extensively studied, although, in these patients, AF contributes to the exacerbation of symptoms and the development of heart failure. The present study determined the role of left atrial (LA) function in the development of AF in patients who have HC. One hundred fifty consecutive patients who had HC, had no history of AF, and who were followed for 5.2 +/- 2.9 years constituted the study population. Using M-mode echocardiography, we measured LA function as global LA fractional shortening and LA diameter. LA volume was measured from 2-dimensional 4-chamber views by the method of disks. During follow-up, 20 patients developed AF. LA function was an independent predictor of AF (odds ratio 0.716, p = <0.001), whereas LA diameter and volume were predictors in addition to age. Kaplan-Meier analysis showed that LA dysfunction carried a high risk of AF. Thus, in patients who have HC, LA function is a strong predictor of AF development and is independent of age.

Adolescent↗

Usefulness of myocardial contrast echocardiographic quantification of risk area for predicting postprocedural complications in patients undergoing septal ethanol ablation for obstructive hypertrophic cardiomyopathy.

Septal ethanol ablation (SEA) is an alternative to surgical myectomy in patients who have drug-refractory obstructive hypertrophic cardiomyopathy. However, permanent atrioventricular conduction block is seen more frequently with SEA. To determine whether septal infarction risk area (SIRA) predicts outcome in patients who have obstructive hypertrophic cardiomyopathy and are undergoing SEA, we evaluated 51 patients (mean age 60 +/- 16, 53% women) who had a successful SEA at Toronto General Hospital (November 1998 to June 2003). Intracoronary myocardial contrast echocardiography that targeted the contact area between the septum and the anterior mitral leaflet was performed before ethanol injection. End-systolic myocardial contrast echocardiographic frames were color coded for better delineation of contrast borders, and myocardial contrast echocardiographic area was calculated by planimetry. Patients were assigned to 1 of 2 groups by median SIRA value (3.51 cm(2), range 0.4 to 7.8). The 2 groups did not differ significantly in age, medication before SEA, electrocardiographic characteristics, left ventricular function, left atrial diameter, volume of intracoronary ethanol injected, peak creatine kinase after ablation, and baseline and follow-up left ventricular outflow tract gradients at rest. Patients in the large SIRA group had greater hypertrophy and a larger septal artery than did patients in the small SIRA group. In the small SIRA group, 3 patients (11.5%) had pacemaker implantation; in the large SIRA group, 12 patients (48.0%) had complications after SEA (pacemaker in 5 patients, implantable defibrillator in 5 patients, death in 2 patients; p = 0.008). We conclude that patients who have hypertrophic cardiomyopathy with a small, well-localized SIRA benefit similarly from SEA as patients who have a larger SIRA but with significantly fewer serious complications.

Cardiomyopathy, Hypertrophic↗

Excellent results for atrial fibrillation surgery in the presence of giant left atrium and mitral valve disease.

OBJECTIVE: The incidence of sinus conversion in the enlarged left atrium after atrial fibrillation surgery is reported to be low. The purpose of the current study was to investigate the effects of atrial fibrillation surgery on mitral valve disease associated with a giant left atrium (GLA). METHOD: From July of 1997 to February of 2002, 188 patients received mitral valve and atrial fibrillation surgery. The patients were placed in either GLA group (n = 94), or NGLA group (n = 94), based on LA size. The presence and onset of sinus rhythm and the incidence and velocity of transmitral A waves were monitored during the early postoperative period and throughout the follow up period of 42 months. RESULTS: The onset of postoperative sinus rhythm was slightly earlier in the NGLA group than in the GLA group at 1.3+/-0.4 days versus 3.1+/-1.2 days, respectively, (P = 0.008). The sinus conversion rates in the GLA and the NGLA groups were 91.5 and 97.9% in the early postoperative period, and 94.7 and 95.7% at 6 months after surgery, respectively. A wave appearance rates in the early postoperative period in the GLA and the NGLA groups were 62.2 and 71.7%, and continued to improve over time to 94 and 95% by 36 months, respectively. Peak A wave velocities in the early postoperative period in GLA and NGLA groups were 67.4+/-34.0 and 61.1+/-29.5 cm/s without significant change during the follow up. CONCLUSION: The results suggest that atrial fibrillation surgery is effective at inducing sinus rhythm and restoring left atrial contractile function after concomitant mitral valve surgery regardless of LA size.

Atrial Fibrillation↗

Augmentation of insulin-stimulated ANP release through tyrosine kinase and PI 3-kinase in diabetic rats.

The aim of present study was to define the effects of insulin on atrial dynamics and ANP release and its modification in diabetic rats. An isolated perfused beating atrial model was used from control and diabetic rats. Insulin was perfused with and without an inhibitor for tyrosine kinase or phosphatidylinositol 3-kinase (PI 3-kinase). Insulin increased the release of ANP and decreased atrial contractility in a dose-dependent manner. During the perfusion of 10(-10)M insulin, the release of ANP abruptly increased within 8min by approximately 40% and then decreased with time despite of continuous perfusion. In terms of increasing the dose of insulin, the time to reach the peak effect became faster and the slope to decrease became slower. In contrast, atrial contractility was gradually decreased with time. These effects were independent upon extracellular glucose. Genistein (10(-5)M) or lavendustin C (10(-5)M), a tyrosine kinase inhibitor, attenuated the release of ANP stimulated by insulin (10(-8)M). Wortmannin (10(-7)M) or LY294002 (10(-5)M), a PI 3-kinase inhibitor, also attenuated insulin-stimulated ANP release. However, both inhibitors for PI 3-kinase and tyrosine kinase did not cause any significant effects on negative inotropism by insulin. Insulin-stimulated ANP release was augmented in streptozotocin-treated rat atria. The density of insulin receptor markedly increased in diabetic hearts. These results suggest that insulin stimulates the release of ANP through PI 3-kinase and tyrosine kinase, and augmentation of insulin-stimulated ANP release in diabetic rat atria may be partly due to an upregulation of insulin receptor.

Animals↗

Clinical, echocardiographic, and hormonal factors influencing spontaneous conversion of recent-onset atrial fibrillation to sinus rhythm.

The present study was designed to determine clinical, hormonal, and echocardiographic factors influencing spontaneous conversion to sinus rhythm of recent-onset atrial fibrillation (symptoms <6 hours). The most important predictor of spontaneous conversion was the time of onset of atrial fibrillation; patients who developed the arrhythmia during sleep had the highest probability of spontaneous conversion during the first 24 hours. A second predictor was the plasma concentration of atrial natriuretic peptide during the arrhythmia.

Adult↗

Differential atrial stunning after electrical cardioversion: an echo tissue Doppler case study.

Left atrial stunning after cardioversion is a well-known phenomenon. It has been associated with higher risk of postcardioversion thromboemboli and increased risk of recurrence of atrial fibrillation. We present a case of differential atrial stunning after electrical cardioversion for atrial fibrillation. Diagnosis was made by pulsed wave Doppler of mitral, tricuspid, and pulmonary vein inflow and mitral and tricuspid annuli. Differential mechanical atrial stunning may be a common phenomenon after cardioversion and may suggest difference in right and left atrial transport function. Its prevalence needs to be determined by a large study. Doppler tissue imaging might be routinely used in patients after cardioversion for atrial fibrillation to detect atrial stunning.

Aged↗

Left atrial systolic reserve in idiopathic vs. ischaemic-dilated cardiomyopathy.

PURPOSE: There are studies indicating more pronounced left atrial (LA) systolic dysfunction at rest in idiopathic (IDDC) than in ischaemic-dilated cardiomyopathy (ISDC). It was hypothesized that the findings would be similar with regards LA systolic reserve. METHODS: Twenty-six patients with IDDC, 28 with ISDC and 25 normal controls underwent low-dose dobutamine stress echocardiography (5-10 microg kg(-1) min(-1) IV). Left atrial volumes were echocardiographically determined at rest and during stress at the mitral valve opening (maximal, Vmax), electrocardiographic P wave (onset of atrial systole, Vp) and mitral valve closure (minimal, Vmin) from the apical 4- and 2-chamber views (biplane area-length method). Left atrial systolic function was assessed with the LA-active emptying volume (ACTEV) = Vp-Vmin and fraction (ACTEF) = ACTEV/Vp. RESULTS: Vmax at rest was similar in IDDC and ISDC and greater than in the controls (54.2 +/- 12 vs. 48.5 +/- 18 vs. 27.1 +/- 6.3 cm(3) m(-2), respectively, P < 0.001) and did not change with stress (53.9 +/- 13.8 vs. 46.9 +/- 16.2 vs. 25.8 +/- 5.9 cm(3) m(-2), P < 0.001). The ACTEV at rest was similar in IDDC and ISDC and greater than in the controls (8.6 +/- 3.5 vs. 9.7 +/- 2.9 vs. 6.1 +/- 2.2 cm(3) m(-2) P < 0.01), whereas during the dobutamine infusion it remained unaltered in IDDC (10.8 +/- 4.6 cm(3) m(-2), P = NS vs. rest) and increased in ISDC (11.8 +/- 3.3 cm(3) m(-2), P < 0.05) and the controls (13.1 +/- 3.2 cm(3) m(-2), P < 0.01). The ACTEF was lower in IDDC than ISDC and the controls at rest (20 +/- 10% vs. 33 +/- 8% vs. 36 +/- 10%, P < 0.01). Dobutamine infusion was associated with no significant increase in ACTEF in IDDC (25 +/- 12%, P = NS vs. rest), and with an increase in this variable in ISDC (39 +/- 10%, P < 0.05) and the controls (49 +/- 12%, P < 0.01). CONCLUSIONS: Dobutamine infusion is associated with an increase in LA ACTEV and fraction in ISDC and no significant change in these indices in IDDC. These findings indicate a reduced LA systolic reserve in IDDC.

Adult↗

Appearance of atrial sound after reversion of atrial fibrillation.

To determine the incidence and time of onset of the atrial sound after reversion of atrial fibrillation in patients with myocardial disease, 12 patients with arteriosclerotic heart disease and 4 patients with primary myocardial disease were followed with serial auscultation as well as daily simultaneous apical phonocardiogram, apex cardiogram, and lead II electrocardiogram. Their average age was 52.3 years. Each patient had been in atrial fibrillation for 6 months to 2 years' duration; 13 were reverted to sinus rhythm with DC capacitor discharge and 3 with quinidine sulphate. All 16 patients developed an atrial sound when in sinus rhythm, but only 2 on the day of reversion; the other 14 patients developed an atrial sound on the first to the sixth day after reversion (average third day). The atrial sound persisted in each patient. This study indicates that the atrial sound as a manifestation of diminished ventricular compliance may be absent in patients with myocardial disease immediately after reversion of atrial fibrillation and may later appear as left atrial function improves.

Adult↗

Pre-clinical and clinical experience of telmisartan in cardiac remodelling.

Epidemiological studies have established that left ventricular hypertrophy (LVH) is an independent risk factor for cardiovascular and cerebrovascular morbidity and mortality. In turn, hypertension is a well-established risk factor for LVH. Ambulatory blood pressure monitoring has shown that 24-h mean ambulatory blood pressure is a particularly powerful predictor of LVH, being superior to casual clinic blood pressure measurements. The magnitude of the rise in blood pressure in the early morning correlates with the extent of LVH. Prospective studies have shown the advantageous effects of antihypertensive therapy on LVH in terms of regression of left ventricular mass (LVM) and subsequent reduction in overt cardiovascular disease. Meta-analysis has identified differences in the ability of different classes of anti-hypertensive agents to bring about regression of LVH, with agents that target the renin angiotensin system (RAS) appearing superior to other agents, such as beta-blockers and diuretics. The distinct pharmacological features of telmisartan suggest that it may be a suitable agent for managing hypertensive patients because it provides sustained control of blood pressure and appears to be very effective in reversing cardiac remodelling. Pre-clinical evaluation has demonstrated that telmisartan suppresses angiotensin II-induced collagen production and secretion by cultured fibroblasts, and reduces left ventricular weight in different animal models. Several clinical studies have demonstrated that, as well as reducing blood pressure (including 24-h mean ambulatory values), telmisartan brings about LVM regression in patients with hypertension, and improves left ventricular and left atrial function. Comparative studies have shown telmisartan's superiority compared with both hydrochlorothiazide and carvedilol in regressing LVM, the additional activity probably being explained by the sustained blood pressure control and the non-haemodynamic effects of targeting the RAS. The ultimate proof of the clinical value of telmisartan will be provided by the outcome trials ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial/Telmisartan Randomized AssessmeNt Study in aCE iNtolerant subjects with cardiovascular Disease (ONTARGET/TRANSCEND) currently being conducted in high-risk patients.

Angiotensin II Type 1 Receptor Blockers↗

Left atrial appendage flow in nonrheumatic atrial fibrillation : relationship with pulmonary venous flow and ECG fibrillatory wave amplitude.

OBJECTIVE: This study was conducted (1) to examine the relationship between left atrial appendage (LAA) flow velocity and pulmonary venous flow (PVF) variables during nonrheumatic atrial fibrillation (AF), and (2) to determine whether a reduction in LAA flow is reflected by the fibrillatory wave amplitude on the surface ECG. BACKGROUND: Although LAA Doppler echocardiographic signals provide information regarding the velocity and direction of flow only for a localized narrow sample, systolic PVF represents in part the global left atrial function, mainly relaxation. Controversy exists about whether the amplitude of fibrillatory waves recorded on the surface ECG correlates with LAA flow velocity during AF. MEASUREMENTS AND RESULTS: Thirty-three patients (20 men, 13 women; mean [+/- SD] age, 61 +/- 11 years) with nonrheumatic AF undergoing transthoracic and transesophageal echocardiography were studied. A correlation between LAA flow velocity and systolic PVF variables (peak systolic velocity, R: = 0.450, p = 0.009; velocity-time integral of systolic flow, R = 0.491, p = 0.004; systolic fraction of PVF, R: = 0.627, p < 0.0001) was observed. Patients with a low LAA flow profile (< 25 cm/s) had a reduced systolic PVF. Longer AF duration and the occurrence of moderate mitral regurgitation were related to reduced LAA flow. AF was subdivided into coarse (peak-to-peak fibrillatory amplitude > or = 1 mm) or fine (< 1 mm) in standard ECG lead V1. There was no association between the coarseness of AF and the LAA flow profile. CONCLUSION: In patients with nonrheumatic AF, a reduction in LAA flow velocity correlates with a reduction in systolic PVF. These hemodynamic changes are not reflected by the ECG fibrillatory wave amplitude.

Aged↗

Left atrial appendage-flow velocity predicts cardioversion success in atrial fibrillation.

Restoration of sinus rhythm by electrical cardioversion is a therapeutic option in appropriately selected patients with atrial fibrillation. It is important to determine predictors of electrical cardioversion outcome in patients with atrial fibrillation. Predictive value of clinical and conventional echocardiographic parameters for predicting cardioversion outcome is limited. The role of left atrial appendage (LAA) function, which may reflect left atrial contractile function, for prediction of cardioversion outcome remains unclear. We conducted a single center prospective study to evaluate the role of LAA function for prediction of cardioversion success in patients with atrial fibrillation. One hundred sixty three patients with atrial fibrillation underwent transthoracic and transesophageal echocardiography (TEE) before electrical cardioversion. LAA functions, including LAA peak flow velocity, LAA area and LAA ejection fraction, were examined. Cardioversion was successful in 133 patients and unsuccessful in 30 patients. Mean LAA peak emptying flow velocity was significantly higher in the patients with successful cardioversion than in those with unsuccessful cardioversion (0.34 +/- 0.14 vs 0.27 +/- 0.1 m/sec; p = 0.013). At multivariate logistic regression analysis, only LAA flow velocity (> 0.28 m/sec, odds ratio = 2.8 ; p = 0.03) proved to be an independent predictor of cardioversion success. LAA area (p = 0.18) and LAA ejection fraction (p = 0.52) were not different between successful and unsuccessful cardioversion groups. Therefore, measurement of LAA flow velocity provides valuable information for prediction of cardioversion outcome in patients with atrial fibrillation before TEE guided cardioversion.

Aged↗

Atrial fibrillation in hypertrophic cardiomyopathy: mechanisms, embolic risk and prognosis.

Hypertrophic cardiomyopathy (HCM) is associated with an increased incidence of supraventricular and ventricular arrhythmias. Atrial fibrillation (AF) is the most common arrhythmia in HCM with a prevalence of 20% and an annual incidence of two percent per year. Increased left atrial size and volume along with impaired left atrial function confer an increased likelihood of AF. The onset of AF is often accompanied by a decrease in functional status in conjunction with an increased risk of stroke and overall mortality.

Atrial Fibrillation↗