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At least 613 records · Page 34Linked to original sources
PubMed1999

Antiarrhythmic surgery for treatment of atrial fibrillation--new concepts.

Curative treatment of atrial fibrillation is one of the main challenges of todays electrophysiology. The ideal treatment strategy should be effective, safe, and easy to apply to allow a widespread use. In addition, curative treatment should not only aim on the restoration of sinus rhythm but also restore mechanical atrial function to improve hemodynamics thereby avoiding anticoagulation. With respect to percutaneous catheter ablation no treatment concept with proven efficiency to cure chronic permanent atrial fibrillation is currently available. Surgical techniques such as the Corridor operation and the left atrial isolation procedure have been shown to effectively store sinus rhythm but these procedures do not restore biatrial transport function. Cox's Maze procedure is highly effective, however, it is an extensive and very time consuming technique which precludes the widespread application of this operation. Thus, new intraoperative treatment concepts are currently under intense clinical investigation. Most new concepts aim on the application of contiguous radiofrequency-induced lesion lines in the atria. Some of the new treatment strategies are based on the replacement of the surgical incisions of the Maze procedure using inrtraoperative radiofrequency coagulation thereby preventing functional determined reentrant circuits. Other new concepts aim on the induction of contiguous atrial lesion lines to eliminate anatomical determined atrial reentrant circuits. The main advantage of these new concepts when compared to the Maze procedure is a significantly shorter treatment time of approximately 20 minutes. In addition, some treatment strategies can also be applied in conjunction with minimally invasive cardiac surgery. The initial results reported with application of new treatment concepts indicate that approximately 60-80% of patients operated on can be cured from atrial fibrillation. Randomised studies with these new treatment strategies are necessary to validate the results and to outline which treatment concept may prove superior to others. Based on the progress made, it can be expected that intraoperative ablation of chronic permanent atrial fibrillation will become an important curative treatment strategy.

Atrial Fibrillation↗
PubMed1994

[Influence of cardiac structure, blood flow velocity and heart function on circulating atrial natriuretic peptide and renin-angiotension system].

Heart function and plasma atrial natriuretic peptide (ANP), plasma renin activity (PRA) and angiotension II (Ang II) were examined with echocardiography and radioimmunoassay in 9 patients with dilated cardiomyopathy (DCM), 41 with rheumatic heart disease (RHD), 29 with hyperthyroidism (Ht) and 24 normal subjects. ANP level was significantly increased as heart failure progressed (P < 0.01 and 0.001). There was negative correlation between ANP and left ventricular fractional shortening, and between ANP and ejection fraction in DCM and Ht groups. There was positive correlation between ANP and maximal left atrial diameter, right atrial area, and diastolic diameter or volume of left ventricle in DCM and RHD groups, and negative correlation between ANP and peak flow velocity in aorta or through mitral valve in DCM group (r = -0.608, P < 0.05 and r = 0.710, P < 0.05). These findings suggest that the stronger the myocardial contractility and the faster the blood flow, the lower the plasma ANP level.

Adult↗
PubMed1998

Estimation of Right Atrial Volume and Function by an Online Echocardiographic Edge Detection System.

To define the accuracy of real-time two-dimensional echocardiographic imaging with automatic border detection (ABD) for the assessment of right atrial volume and function, we studied with ABD echocardiography 29 healthy subjects and 43 patients with sinus rhythm and various forms of heart disease. Twenty-three patients had right ventricular (RV) dysfunction (fractional area change < 45%), and 20 had RV hypertrophy from pressure overload. Doppler color flow imaging disclosed moderate-to-severe tricuspid regurgitation (TR) in 20 patients and trivial or no TR in 23. The ABD-derived end-diastolic (EDV) and end-systolic (ESV) volumes by the method of discs were used to compute fractional indexes of right atrial (RA) volume changes. Right atrial emptying fraction (RAEF) percent [(ESV - EDV)/ESV x 100] was calculated. The ABD-derived EDV and ESV correlated well with conventional offline measurements of two-dimensional echocardiographic images in the 43 patients (r = 0.94 for the end-diastolic values; r = 0.93 for the end-systolic values). Intraobserver and interobserver variability showed a high correlation between different measurements (r = 0.97 and 0.90, respectively). RA volumes were significantly higher in the patient population than in the control subjects (148.9 +/- 66.7 ml vs 43.1 +/- 9.2 ml, P < 0.0001). The right atrial emptying fraction (RAEF) was higher in patients with RV pressure overload than in normal subjects (61% +/- 11% vs 46% +/- 9%, P < 0.05) and lower in those with RV dysfunction than in the control subjects (29% +/- 7% vs 46% +/- 9%, P < 0.01). In both groups (RV pressure overload and RV dysfunction), RAEF was higher in patients without or with trivial TR compared with those with significant TR (29% +/- 7% vs 23% +/- 6%; 61% +/- 11% vs 42% +/- 7%; P < 0.05). Thus, changes in right atrial volume and function can be measured noninvasively by the ABD method. This imaging technique may prove to be useful for assessing right atrial size and function under different physiological and pathological conditions and for identifying factors that influence atrial function in right ventricular diseases.

Journal Article↗
PubMed1997

Our tortuous heart in dynamic mode--an echocardiographic study of mitral flow and movement in exercising subjects.

Blood traces tortuous paths of flow through the heart. We postulate that momentum changes associated with direction changes optimize dynamic coupling between ventricular and atrial function, particularly on exercise. Traces of pulsed Doppler mitral flow and M-mode long-axis mitral ring movement were recorded before and during exercise, increased in 25-W steps to strenuous levels (146 +/- 30 W), in 16 healthy volunteers, aged 38 +/- 10 years. R-R intervals fell from 821 +/- 151 to 437 +/- 51 ms, and diastole from 458 +/- 134 to 169 +/- 33 ms. Peak mitral flow velocities rose from 0.68 +/- 0.17 to 1.27 +/- 0.16 m/s, and mitral valve ring displacements from 13.8 +/- 3.3 to 19.3 +/- 3.4 mm. Biphasic diastolic curves of flow and movement became monophasic as R-R fell below 500 ms, with atrial systole apparently coming to coincide with elastic ventricular recoil to give a single elevated peak of mitral flow. The increased slope and amplitude of Doppler curves indicate increased rates of change of momentum, which imply enhanced inertial forces. The illustrated patterns of flow and movement on exercise accord with the postulated "dynamic" mode of function, in which forces between atria, ventricles, and passing blood masses become tightly coupled to achieve a sling-like redirection of momentum through tortuous paths of flow, but more extensive data are needed to adequately model and quantify inertial force exchanges of the exercising heart.

Adult↗
PubMed1999

Intraoperative microwave ablation for curative treatment of atrial fibrillation in open heart surgery--the MICRO-STAF and MICRO-PASS pilot trial. MICROwave Application in Surgical treatment of Atrial Fibrillation. MICROwave Application for the Treatment of Atrial Fibrillation in Bypass-Surgery.

Concomitant microwave ablation for curative treatment of atrial fibrillation (AF) was performed in 18 patients with history of chronic atrial fibrillation and indication for open heart surgery, 11 patients with mitral valve replacement and 7 patients with coronary artery bypass grafting. There were no perioperative complications. During the postoperative period most of the patients had intermittent AF, they received low dose Sotalol therapy and electric cardioversions. Up to now seven patients have reached follow-up day 90. One patient has persistent AF. Two patients had typical atrial flutter that was electrically converted to sinus rhythm (SR), isthmus ablation is planned. The other four patients have SR, one patient without cardioversions. These four patients show recovered atrial function with observed A-wave for transmitral flow. Under visual guidance the continuous atrial lesion lines could be induced effectively and safely by the intraoperative device Lynx.

Aged↗
PubMed1996

[Flow in pulmonary veins].

Pulmonary venous flow can be evaluated by means of pulsed Doppler echocardiography during a transthoracic or transesophageal echocardiography examination. In most cases a three-peak spectral curve with highest positive wave during ventricular systole, a lower positive wave during ventricular diastole and a small negative wave during the left atrial contraction are recorded. Multiple factors affect the systolic and diastolic components of pulmonary venous flow. Pulmonary venous flow measurement may prove to be an important tool in routine judgment of diastolic left ventricular and atrial function. With regard to clinical importance, the pulmonary venous flow is a useful parameter for left atrial pressure quantification and for differential diagnosis of restrictive cardiomyopathy and constrictive pericarditis.

Blood Flow Velocity↗
PubMed2005

Spironolactone reduces fibrosis of dilated atria during heart failure in rats with myocardial infarction.

AIMS: Congestive heart failure (CHF) is associated with severe structural changes of atria, contributing to impaired atrial function and the risk of arrhythmia. This study investigated the effects of CHF treatments on atrial remodelling. METHODS AND RESULTS: Three months after myocardial infarction (MI), rats were treated for 1 month with spironolactone, lisinopril, or atenolol alone or in combination. Echocardiography-Doppler tissue imaging, haemodynamic measurements, and 24-h Holter monitoring were used to characterize the cardiomyopathy. Atrial fibrosis was quantified with Picrosirius Red staining. Left atrial diameter was increased (5.8+/-0.6 mm in MI vs. 3.6+/-0.3 mm in sham; P<0.0001), as was atrial fibrosis (26.7+/-3.8% in MI vs. 10.5+/-2.2% in sham; P<0.0001), which correlated with left ventricular (LV) dysfunction after 3 months of MI. P-wave duration was also increased and premature atrial beats were frequent on the 24-h electrocardiogram. Similar improvements in LV dysfunction were observed after 1 month of spironolactone, ACE-inhibitor, or beta-blocker therapy alone or in combination. Atrial hyperexcitability was reduced by all the treatments, but only spironolactone attenuated atrial fibrosis and reduced P-wave duration. CONCLUSION: Atrial fibrosis caused by chronic CHF is reduced by spironolactone.

Animals↗
PubMed1975

Effects of atrial pacing site on atrial and atrioventricular nodal function.

The effects of the site used for atrial pacing on atrial and atrioventricular nodal conduction were assesed in 16 patients. In 13 patients, three atrial pacing sites were used: high right atrium, low lateral right atrium, and midcoronary sinus. Two recording sites were used: low septal right atrium, including His electrogram, and high right atrium. Stimulus (S) to high right atrium interval was longest with coronary sinus pacing (76 plus or minus 7 ms) (P less than 0.001), and shortes with high right atrial pacing (41 plus or minus 3 ms) (P less than 0.05). There was no significant difference in stimulus to low septal right atrium from all three pacing sites. Atrial functional and effective refractory periods were not significantly different. Mean low septal right atrium to His was significantly shorter from the coronary sinus (93 plus or minus 8 ms) (P less than 0.001), as compared to high right atrium (139 plus or minus 16 ms), and low lateral right atrium (129 plus or minus 13 ms) pacing. AV nodal functional and effective refractory periods, and the paced rate producing AV nodal Wenckebach were not significantly different when comparing the three sites. Left atrial appendage and high right atrium were similarly compared in three additional patients, and no significant differences were found in conduction times and refractory periods.

Adult↗
PubMed2000

Maternal cardiac systolic and diastolic function: relationship with uteroplacental resistances. A Doppler and echocardiographic longitudinal study.

OBJECTIVE: To test the hypothesis of the existence of a relationship between central and peripheral hemodynamic parameters by the longitudinal evaluation of maternal echocardiographic and uteroplacental resistance modifications during normal pregnancy. METHODS: Forty-three healthy normotensive primigravidae were evaluated at 12 +/- 1, 21 +/- 1, and 33 +/- 1 weeks of gestation with uterine artery color Doppler and maternal echocardiographic examinations to identify morphologic, systolic, and diastolic variables. RESULTS: Cardiac output and stroke volume significantly increased during pregnancy. Uterine resistance index (RI) decreased from the first to the second trimesters (0.72 +/- 0.10 versus 0.54 +/- 0.09, P < 0.001). Left atrial dimensions increased during pregnancy (33.8 +/- 1.9 cm, 38.1 +/- 1.8 cm, 39.3 +/- 2.1 cm, P < 0.001). Left atrial function also increased. Left ventricular mass increased (132 +/- 18 g, 162 +/- 16 g, 174 +/- 27 g, P < 0.001). Diastolic function parameters showed significant modifications: E wave velocity and E/A ratio decreased; A wave velocity and deceleration time of the E wave (DtE) increased; the left ventricular isovolumetric relaxation time (IVRT) decreased significantly (88.7 +/- 6.7 ms, 75.6 +/- 7.7 ms, 71.1 +/- 5.0 ms, P < 0.001) showing a correlation with left atrial dimensions and RI (r = -0.38, r = 0.47, respectively; P < 0.001). CONCLUSIONS: Diastolic cardiac function varies during pregnancy. A relationship between preload (left atrial enlargement), afterload (RI reduction), morphologic, and diastolic function modifications (IVRT reduction, DtE prolongation) appears to exist as a consequence of the hemodynamic modifications which occur during physiologic pregnancy. Diastolic function analysis maybe useful to identify women who fully adapt to pregnancy, and to understand the mechanisms that might be involved in women who show abnormal uterine artery Doppler waveforms.

Adult↗
PubMed1996

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

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

Adult↗
PubMed2002

Impaired sinus node function and global atrial conduction time after high rate atrial pacing in dogs.

In animal and human studies, it has been shown that atrial fibrillation shortens the atrial refractory period and impairs its rate adaptation. The objective of this study was to evaluate the effects of high-rate pacing on sinus node function and intra-atrial conduction. Eight dogs were subjected to rapid atrial pacing (AP) at 400 bpm for 16 days. Sinus node recovery time (SNRT) and P-wave duration were measured at baseline, immediately after AP and four weeks after the termination of AP. SNRT immediately after AP was significantly prolonged at all pacing rates compared to the baseline values. P-wave duration was significantly longer after AP relative to the baseline values. All the variables were completely reversible four weeks after the termination of pacing. Rapid AP induces sinus node dysfunction and prolongs the intra-atrial conduction time. It is possible that the electrical remodelling extends to the sinus node as well.

Animals↗
PubMed1985

Electrophysiology of esmolol.

The electrophysiologic characteristics of esmolol were studied in 14 patients. Ten men and 4 women, mean age 57 years, were electrophysiologically evaluated at baseline, and also at 4 to 8 minutes after the administration of a maintenance infusion of esmolol. Plasma samples for esmolol blood levels were drawn at 10 minutes of the maintenance infusion, at the end of the maintenance infusion and 30 minutes after the maintenance infusion was discontinued. Results of this study showed that esmolol has typical beta-blocker electrophysiologic effects. Its major action was on sinus node function; it prolonged this basic sinus cycle length but had no significant effect on intrinsic automaticity as reflected by the corrected sinus node recovery time and sinoatrial conduction. Direct effects on atrioventricular (AV) nodal function were reflected by effects on AV nodal conduction and refractoriness. There was no direct effect on atrial function and, as expected, no effect on His-Purkinje or ventricular function. The intensity of esmolol's electrophysiologic effects on sinus node function, AV nodal conduction and AH interval is comparable to those of other beta blockers.

Adrenergic beta-Antagonists↗
PubMed2006

Efficacy and safety of right and left atrial ablations on the beating heart with irrigated bipolar radiofrequency energy: a long-term animal study.

OBJECTIVE: The Cox maze procedure is the most effective surgical treatment for atrial fibrillation; however, its complexity has limited its clinical utility. The purpose of this study was to simplify the procedure by using an irrigated bipolar radiofrequency ablation device on the beating heart without cardiopulmonary bypass. METHODS: Six domestic pigs underwent median sternotomy. The pulmonary veins were circumferentially ablated. Electrical isolation was confirmed by pacing. Eight lesions were performed epicardially, and three lesions were performed through purse-string sutures with one of the jaws of the device introduced into the right atrium. After 30 days, magnetic resonance imaging was performed to assess atrial function, pulmonary vein anatomy, and coronary artery patency. Cholinergic stimulation and burst pacing were administered to induce atrial fibrillation. Histologic assessment of the heart was performed after the animal was killed. RESULTS: A modified Cox maze procedure was successfully performed with the irrigated bipolar radiofrequency device with no deaths. In every instance, the pulmonary veins were electrically isolated. Cholinergic stimulation with burst pacing failed to produce atrial fibrillation. Imaging studies revealed tricuspid regurgitation without evidence of pulmonary vein stenosis, coronary artery stenosis, or intra-atrial thrombus. Total atrial ejection fraction was 16.9% +/- 7.5%, a significant reduction. Histologically, 99% of the lesions were transmural, and there was no evidence of coronary sinus injury. CONCLUSION: Lesions on both the right and left atria can be created successfully on the beating heart with irrigated bipolar radiofrequency. The great majority of lesions with this device were transmural. This device should not be used on valvular tissue.

Animals↗
PubMed1980

Differential atrial filling after Mustard and Senning repairs. Detection by transcutaneous Doppler ultrasound.

The dominance of Mustard's operation for transposition of the great arteries has been challenged by the recent revival of Senning's repair because it promises better long-term results in terms of venous obstruction and atrial haemodynamics. These hypotheses were tested by recording jugular venous flow waveforms transcutaneously in 24 postoperative patients with simple complete transposition using a bidirectional Doppler blood velocimeter. Eight patients had undergone Mustard's operation and 16 the Senning alternative; all had previously had a postoperative cardiac catheterisation. Both groups of patients had similar left ventricular, pulmonary arterial, and systemic venous atrial pressures. No child showed any evidence at catheterisation of either mitral regurgitation or of superior vena caval pathway obstruction. These two findings were endorsed by the transcutaneous Doppler recordings. Jugular venous flow in normal children exhibits two maxima, one of atrial filling during ventricular systole, the other of ventricular filling occurs once the tricuspid valve has opened. Both operative procedures diminished the size of the former phase, but the Mustard did so more. After Mustard's operation forward flow during the atrial filling phase was absent in approximately half the cardiac cycles recorded, and severely diminished in the rest. By contrast, there was approximately a 90 per cent appearance of atrial filling waves after Senning's operation which also provided significantly better atrial function than Mustard's procedure in terms of peak velocity of blood entering the atrium and total atrial filling. It is therefore concluded that both procedures compromise atrial volume and compliance but Senning's repair to a much lesser extent.

Blood Flow Velocity↗
PubMed1988

Effects of left ventricular dysfunction on left atrial performance in previous myocardial infarction and during pacing-induced myocardial ischemia in angina pectoris.

This study aimed to evaluate acute and chronic response of left atrial function to left ventricular dysfunction in patients with coronary artery disease. We studied simultaneous measurements of left atrial volume by biplane cineangiography and left ventricular pressure at rest and after pacing in 59 patients with coronary artery disease and 11 normal subjects. At rest, 35 patients with previous myocardial infarction (MI group) had low left ventricular filling rate of the first third in diastolic time, large left atrial volume before contraction (LA pre-ACV) and large left atrial ejection volume (LAEV), compared with control group. Left atrial ejection fraction (LAEF), the ratio of LAEV to LA pre-ACV, was similar between both groups. LAEF was maintained within a wide range of values in accordance with left ventricular peak A pressure, except for 3 patients who had high values of left ventricular peak A pressure and low values of LAEF. After a right atrial pacing stress test, time constant was prolonged and mean emptying rate of left atrial volume during early diastole decreased in 11 patients with angina pectoris who had an increase greater than 5 mmHg in left ventricular end-diastolic pressure after pacing. In these group, LA pre-ACV increased, LAEF decreased and LAEV was unchanged. These results suggest that left atrial performance responds differently to acute and chronic left ventricular dysfunction in patients with coronary artery disease.

Angina Pectoris↗
PubMed1989

[Electrophysiologic effects of calcium channel blockers on supraventricular tachycardia in children].

Calcium channel blockers (diltiazem or verapamil) were administered in 17 pediatric patients with supraventricular tachycardia to evaluate their drug effects on electrophysiologic properties and the tachycardia zone. Using electrophysiologic technique, 10 patients were diagnosed as having orthodromic reciprocating tachycardia (ORT), including three patients with concealed atrioventricular bypass tracts. Four patients were diagnosed as having atrioventricular nodal re-entrant tachycardia (AVNRT) of the slow-fast type and three patients were diagnosed as having intra-atrial re-entrant tachycardia (IART). Diltiazem was given to 10 patients; verapamil, to eight patients at doses of 0.15-0.2 mg/kg intravenously. Electrophysiologic properties and the tachycardia zone were then evaluated before and after the administration of calcium channel blockers. Diltiazem and verapamil produced no significant changes in the sinus node and atrial functions including basic sinus cycle length, sinoatrial conduction time, maximum sinus node recovery time and the effective atrial refractory period. Although sinus cycle length was shortened after verapamil in half the cases, it was due to increased sympathetic tone secondary to hypotension rather than to direct action of verapamil. Calcium channel blockers, however, prolonged the PR interval and significantly increased the effective refractory period of the atrioventricular node. Properties of the atrioventricular bypass tracts were not affected by calcium channel blockers. Diltiazem and verapamil were markedly effective in ORT and AVNRT. Their re-entrant circuits, including the atrioventricular node and the tachycardia zones, were shortened or resolved. However, IART showed no significant change in the tachycardia zone after the administration of calcium channel blockers, because the re-entrant circuit was not present within the atrioventricular node.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1997

[Function of the left heart atrium during hemodialysis].

In 23 chronic uremic patients effect of four-hour hemodialysis on function the left atrium of the heart was investigated. The reference group consisted of 17 healthy subjects. The function was evaluated by cross-sectional Doppler echocardiography. Before hemodialysis maximal (LAmax) and minimal (LAmin) left atrial dimensions and left atrial dimension obtained in M-mode of long axis in parasternal projection (LAa), pre-ejection period (PEPlp), ejection time (ETlp), PEPlo/ETlp ratio and left atrial fiber shortening fraction (FS%lp) were significantly higher in chronic uremic patients than those found in healthy subjects. Four-hour hemodialysis induced decreases in these indices, but only a lowering of LAa, PEPlp/ETlp ratio was statistically significant in comparison with pre-dialysis period. No correlation was found between changes of the investigated indices of the left atrial function and body weight loss during hemodialysis.

Adult↗