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PubMedDate not supplied

A prospective study of left atrial spontaneous echo contrast and thrombus in 100 consecutive patients referred for balloon dilation of the mitral valve.

The aim of this study was to determine the clinical, echocardiographic, and hemodynamic predictors of left atrial spontaneous echo contrast (SEC) and thrombus, respectively, in patients referred for balloon dilation of the mitral valve and to establish the relationship between the two phenomena in this group of patients. One hundred consecutive patients (mean age 57 +/- 14 years) referred for mitral balloon (Inoue) dilation were studied prospectively with transthoracic and transesophageal (83 biplane and 17 single plane) echocardiography (TEE) combined with spectral and color Doppler modalities, immediately before the procedure. TEE was repeated within 24 hours of valvotomy in the first 55 patients. All patients also underwent comprehensive left- and right-sided heart catheterization. TEE was performed successfully in 96 patients. SEC was detected in all 65 patients in atrial fibrillation and in 14 (45%) of 31 patients in sinus rhythm. Patients with SEC were significantly older (61 +/- 13 vs 45 +/- 12 years; p < 0.001) and had larger left atrial volume (98 +/- 48 vs 64 +/- 24 ml; p < 0.001), higher mitral valve echocardiographic scores (7.4 +/- 3.2 vs 5.3 +/- 2.6; p = 0.016), lower cardiac output (3.5 +/- 1.1 versus 4.6 +/- 0.9 L/min; p < 0.001), lower peak systolic pulmonary vein flow velocity (SVm) (24 +/- 12 versus 45 +/- 11 cm/sec; p < 0.001), and correspondingly lower systolic velocity-time integral (4.0 +/- 2.6 vs 7.9 +/- 2.9 cm; p < 0.001) than had patients without SEC. There were no significant associations between SEC and either mitral valve area or anticoagulant therapy. SVm and atrial fibrillation were found to be independent predictors of SEC. In patients in sinus rhythm, SVm was the only independent predictor of SEC. After mitral balloon dilation, SEC disappeared in only two of 35 patients in atrial fibrillation and in five of eight patients in sinus rhythm. Significant mitral regurgitation occurred in the two patients in atrial fibrillation. TEE detected left atrial thrombus in 14 patients. Thrombus was significantly associated with age, mitral valve area, and the severity of SEC. The latter was found to be an independent predictor of thrombus. Two patients in sinus rhythm had evidence of left atrial mechanical dysfunction. Both patients had left atrial SEC and one had thrombus in the appendage. It is concluded that SEC in patients with severe mitral stenosis is dependent on left atrial systolic function and peak systolic pulmonary vein velocity. It is not related to mitral valve area or anticoagulant therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed2003

Treatment of patent ductus arteriosus.

Patent ductus arteriosus (PDA) continues to be one of the most common problems found in premature infants. The incidence is inversely related to gestation, but may be reduced by use of antenatal steroids, lower volume fluid regimen and judicious use of phototherapy. However, there continues to be controversy as to the appropriate indications for treatment, varying from prophylaxis on the basis of gestation to treatment only when a PDA is demonstrably significant. The situation is further complicated by differing diagnostic criteria for ductal patency or significance. Prophylactic treatment is likely to result in up to 64% of babies being treated unnecessarily. Early treatment of significant or symptomatic PDA depends upon accurate diagnosis. PDA closure can then be achieved using medical means, with surgery reserved for patients in whom this fails or in whom there are contra-indications. However, the optimum timing for intervention remains unknown.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2003

Current controversies in the diagnosis and treatment of patent ductus arteriosus in preterm infants.

This article presents common misconceptions about the physiologic significance of early ductal shunting and reviews the evidence regarding the preferential use of echocardiography rather than reliance on clinical signs to diagnose patent ductus arteriosus. The rationale for the treatment of symptomatic versus presymptomatic versus prophylactic is compared and contrasted. Finally, a novel but untested treatment approach, using early echocardiographic findings to direct treatment decisions, is proposed as a direction for future research.

Atrial Function, Left↗
PubMed2006

Highly chiral muscarinic ligands: the discovery of (2S,2'R,3'S,5'R)-1-methyl-2-(2-methyl-1,3-oxathiolan-5-yl)pyrrolidine 3-sulfoxide methyl iodide, a potent, functionally selective, M2 partial agonist.

By further steric complication of previously studied highly chiral muscarinic agonists, we have obtained a small chiral library of enantiomeric and diasteromeric 1-methyl-2-(2-methyl-1,3-oxathiolan-5-yl)pyrrolidine 3-sulfoxides. Binding studies on cloned human muscarinic receptors expressed in CHO cells show that the introduction of a fourth stereogenic center gives undetectable affinity for hm1, hm3, hm4 and hm5 subtypes while leaving a quite modest affinity only for hm2 subtypes. However, functional studies on model M1-M4 muscarinic tissues have shown that three compounds of the series [(-)-5, (-)-7, (+)-8] are endowed with functional activity and behave as M2 selective partial agonists. Among them, compound (2S,2'R,3'S,5'R)-1-methyl-2-(2-methyl-1,3-oxathiolan-5-yl)pyrrolidine 3-sulfoxide methyl iodide [(+)-8] is particularly interesting, as it is a potent partial agonist on guinea pig atrium (force) (M2; pD2=7.65, alpha=0.41) while being a poor antagonist on M1, M3, and M4 model tissues (pKb<5).

Animals↗
PubMed1999

Intracellular acidosis modulates the stretch-induced changes in E-C coupling of the rat atrium.

By inducing a small reduction of the intracellular pH (0.18 units) with 20 mmol L-1 propionate we demonstrated that acidification changed the responses of isolated rat atria to stretch. Stretch (increase of the intra-atrial pressure) in normal pH increased the Ca2+ transients' amplitude (Indo-1 fluorescence) from 0.26 +/- 0.09 in 1 mmHg to 0.36 +/- 0.13 in 4 mmHg (P < 0.05, n=6), without affecting the diastolic [Ca2+]i level (n.s. n=6). The changes in Ca2+ balance during stretch were accompanied by a biphasic increase in the contraction force. Five minutes of continuous stretch increased the action potential duration (APD90%, P < 0.01, n=13) and decreased the APD15% (P < 0.001, n=13). During acidosis, the stretch-induced increase of the Ca2+ transient amplitude (0.4 +/- 0. 13 vs. 0.3 +/- 0.08, P < 0.05, n=6) was accompanied by the increase of the diastolic [Ca2+]i (1.16 +/- 0.07, P < 0.05, n=6) compared with non-acidotic control (1.06 +/- 0.06, n=6). Acidic intracellular pH also inhibited the stretch-induced changes in the action potentials (n=10) and slowed down the development of the contractile force during stretch. The results showed that acidosis modulates the mechanotransduction. It does this by interfering with the intracellular Ca2+ balance, inhibiting the Ca2+ extrusion mechanisms and reducing the Ca2+-buffering power of the cells. The physiological and pathological processes associated with stretch are therefore modulated by intracellular pH owing to its concerted effects on intracellular Ca2+ handling caused by a competitive inhibition of various Ca2+-binding molecules.

Acidosis↗
PubMed2002

Atrial pacing lead location alters the effects of atrioventricular delay on atrial and ventricular hemodynamics.

The combined role of atrial pacing lead location and AV timing on cardiovascular performance has not been defined. This study tested the hypothesis that atrial pacing lead location can change the dependence of LA and LV hemodynamics on AV timing in vivo. Dogs anesthetized with isoflurane (n = 8) were instrumented for measurement of hemodynamics including LA pressure, LA volume, and pulmonary venous bloodflow. Data were recorded during normal sinus rhythm, and atrial overdrive pacing from the right atrial appendage (RAA), proximal coronary sinus (CS), and LA lateral wall (LAW). The AV node was then ablated and measurements repeated during synchronous ventricular pacing and during dual chamber pacing from each atrial lead location at various AV delays (20, 60, 120, 180, 240, and 350 ms). Hemodynamics during intrinsic sinus rhythm and overdrive atrial pacing from different sites were similar. In contrast, ventricular or dual chamber pacing caused significant (P < 0.05) changes in cardiac output with different AV timing during RAA (3.5 +/- 0.2 vs 2.9 +/- 0.2 L/min at 120 and 350 ms, respectively) and LAW pacing but not CS pacing. A significant interaction between atrial lead location and AV delay was observed for changes in stroke volume, pulmonary venous blood transport, LA volume, and LV preload. The results indicate that the atrial contribution to cardiac output depends on AV timing and atrial lead location in isoflurane-anesthetized dogs with AV nodal conduction block.

Animals↗
PubMed2000

Catheter ablation of atrial flutter guided by electroanatomic mapping (CARTO): a randomized comparison to the conventional approach.

INTRODUCTION: Three-dimensional electroanatomic (CARTO) activation mapping of the cavotricuspid isthmus can be helpful to guide atrial flutter ablation, but to date has not been investigated in comparison to conventional strategies. The aim of the present study was to assess the efficacy of the CARTO navigation system, especially with respect to the fluoroscopy time required for successful atrial flutter ablation. METHODS AND RESULTS: Eighty patients with recurrent common-type atrial flutter were randomly assigned to temperature-controlled radiofrequency (RF) catheter ablation, either guided by conventional criteria (group 1) or additionally oriented on electroanatomic mapping (group 2). In all patients, similar multipolar catheters were inserted into the coronary sinus and placed at the tricuspid annulus, respectively. In group 2, positioning of the mapping electrode and delivery of RF pulses within the cavotricuspid isthmus was mainly oriented on the CARTO map to achieve the most linear and continuous RF lesions. Abolition of intra-atrial conduction verified by conventional criteria (group 1) and electroanatomic mapping (group 2) could be verified in all patients. The overall number of RF pulses (group 1: 16.7+/-6.5; group 2: 13.2+/-5.3) and mean procedure duration (group 1: 172.5+/-47.4 min; group 2: 169.3+/-47.3 min) were not different between the two groups, but mean fluoroscopy time was significantly shorter when the CARTO technology was used (group 1: 29.2+/-9.4 min; group 2: 7.7+/-2.8 min; P = 0.0001). Recurrence of atrial flutter was observed in 3 (9%) patients in each group after a mean follow-up of 8.5+/-2.8 months. CONCLUSION: Atrial flutter can be abolished effectively using the conventional technique as well as oriented on electroanatomic mapping. However, overall X-ray exposure can be significantly reduced by the CARTO-guided approach without prolongation of procedure duration.

Aged↗
PubMed2003

Relationship between the frequency of paroxysmal episodes of atrial fibrillation and pulmonary venous flow pattern.

AIMS: Chronic atrial fibrillation causes mechanical remodelling of the atria, but it is uncertain whether self-terminating episodes of paroxysmal atrial fibrillation (PAF) alter atrial mechanical function during normal sinus rhythm. This study was designed to assess the relationship between the frequency of symptomatic arrhythmic episodes and pulmonary venous flow (PVF) pattern among patients with PAF. METHODS AND RESULTS: The effect of symptomatic arrhythmic episodes on PVF was studied in 85 patients with lone PAF (age 48+/-8 years, 66 men). PVF was measured with transthoracic echocardiography during sinus rhythm. Adequate recordings of PVF were achieved in 81 (95%) patients. Peak systolic PVF had an inverse correlation (r=-0.35, P=0.002) with the frequency of PAF episodes. The peak systolic PVF was 76+/-14 cm/s vs 62+/-12 cm/s (P=0.008) among the quartiles with the most and the least frequent episodes of PAF, respectively. There were no significant differences in the other echocardiographic measurements or demographic variables. CONCLUSIONS: Frequent arrhythmic episodes significantly diminished systolic PVF among patients with PAF, suggesting that PAF results in gradual mechanical remodelling of the atrium, which may favour recurrence and perpetuation of AF and/or formation of atrial thrombus.

Atrial Fibrillation↗
PubMed1993

Effect of atrial fibrillation on pulmonary venous flow patterns: transoesophageal pulsed Doppler echocardiographic study.

The effect of atrial fibrillation on pulmonary venous flow patterns is still not well known. Twenty-four patients in atrial fibrillation and 21 patients in sinus rhythm were studied by transoesophageal echocardiography. In ninety-five percent (20/21) of sinus rhythm patients, the early systolic wave due to atrial relaxation or reverse wave due to atrial contraction could be distinguished on pulsed Doppler tracings by transoesophageal echocardiography. However, there was no early systolic wave and/or reverse at the end of diastole in any atrial fibrillation patients. In atrial fibrillation patients without mitral regurgitation (n = 14), the onset of systolic flow was delayed (165 +/- 38 vs 50 +/- 46 ms, P < 0.05), and systolic peak velocities, time-velocity integrals and systolic fractions were reduced (31 +/- 13 vs 54 +/- 17 cm.s-1, P < 0.05; 5 +/- 2 vs 13 +/- 6 cm, P < 0.05 and 36 +/- 8 vs 61 +/- 15%, P < 0.05, respectively) as compared to those in sinus rhythm. Significant mitral regurgitation (n = 10) reduced systolic velocity parameters considerably in atrial fibrillation patients but the diastolic flow parameters were not significantly different between sinus rhythm and atrial fibrillation patients. Stepwise multiple regression analysis identified atrial fibrillation as an important independent predictor for changes in systolic flow parameters. The R-R interval is also an important factor for diastolic flow parameters. Thus, the present study demonstrates that atrial fibrillation significantly modifies pulmonary venous flow pattern and is an important factor for systolic flow parameters. Significant mitral regurgitation can further modify systolic flow pattern in atrial fibrillation patients.

Adult↗
PubMed2001

Echocardiographic assessment of diastolic function.

Abnormal diastolic function is increasingly appreciated as a major contributor to cardiac morbidity and mortality. Accurate noninvasive assessment of the presence and severity of diastolic impairment is crucial to the broad application and understanding of this common condition. Echocardiographic parameters have become the backbone of this noninvasive assessment. Active investigation into both old and new Doppler variables will provide the framework that can lead to a more uniform assessment and reporting that will be essential as we prepare to confront clinically the next frontier in cardiac pathophysiology. This review discusses the clinical impact of recent echocardiographic contributions to the field of diastology.

Atrial Function, Left↗
PubMed2002

Heart failure accompanied by sick euthyroid syndrome and exercise training.

Sick euthyroid syndrome is defined as the decrease of serum free triiodothyronine with normal free L-thyroxin and thyrotropin. Its appearance in patients with chronic heart failure is an indicator of severity. Exercise training through a wide variety of mechanisms reverses sick euthyroid syndrome (normalization of free triiodothyronine levels) and improves the ability to exercise. There is a connection during exercise among dyspnea, hyperventilation, fatigue, catecholamines, a decrease in the number and function of beta-blocker receptors, and elevation of serum free triiodothyronine. It is not known whether sick euthyroid syndrome contributes to the development of heart failure or is only an attendant syndrome.

Aged↗
PubMed1979

Total artificial heart implantation in calves with pump on an angled port design.

The APP was employed in our 21st TAH calf and has now been implanted in a total of 11 animals. The APP has a dynamic stroke volume of 105 ml, an ejection fraction of 75%, and a peak flow of 14 L/min. The TAH features 2 APPs which have polysulfone cases and contain smooth, seam-free polyurethane sacs. Concavoconvex Bjork-Shiley valves are used. The pumps are pneumatically driven but may be easily converted to pusher-plate drive. A pneumatic drive console and an automatic control unit complete the system. The automatic control unit permits independent control of the right and left hearts as a function of left atrial and aortic pressure respectively. The average survival of the APP TAH calves has been 65 days. Hematologic study has revealed basically normal results with minimal elevation of serum hemoglobin and lactic acid dehydrogenase (LDH), indicative of a low level of hemolysis. Elelvation of central venous pressure (CVP) and total blood volume continue to be a problem with some TAH calves but not all. The APP has led to a dramatic increase in duration of survival and decrease in thromboembolism.

Animals↗