CLINICAL RESEARCH: ATRIAL FIBRILLATION
Left ventricular mechanics during right ventricular apical or left ventricular-based pacing in patients with chronic atrial fibrillation after atrioventricular junction ablation
Emmanuel N. Simantirakis, MD*,
Konstantinos E. Vardakis, MD*,
George E. Kochiadakis, MD*,
Emmanuel G. Manios, MD*,
Nikolaos E. Igoumenidis, MD*,
Michele Brignole, MD and
Panos E. Vardas, MD, PhD, FACC*,*
* Cardiology Department, Heraklion University Hospital, Crete, Greece
Arrhythmologic Centre, Department of Cardiology, Ospedali del Tigullio, Lavagna, Italy
Manuscript received June 9, 2003;
revised manuscript received September 14, 2003,
accepted October 6, 2003.
* Reprint requests and correspondence: Dr. Panos E. Vardas, Cardiology Department, Heraklion University Hospital, P.O. Box 1352 Stavrakia, Heraklion, Crete, Greece.
cardio{at}med.uoc.gr
 |
Abstract
|
|---|
OBJECTIVES: The aim of the study was to evaluate whether left ventricular (LV) mechanics are better under LV-based pacing than under right ventricular (RV) apical pacing in patients with permanent atrial fibrillation (AF) after atrioventricular junction (AVJ) ablation.
BACKGROUND: "Ablate and pace" is an acceptable therapy for drug-refractory AF. However, the RV apical stimulation commonly used seems to interfere with the beneficial hemodynamic effect of regularization of heart rhythm.
METHODS: The study included 12 patients (5 men, mean age 62 ± 8.3 years), 6 with impaired and 6 with normal LV systolic function. All of them had a biventricular pacemaker system implanted and underwent atrioventricular node ablation for drug-refractory chronic AF. Using a conductance catheter, we analyzed LV pressure–volume loops during routine coronary angiography in order to evaluate short-term changes in LV mechanics during RV apical and LV-based (LV free wall or biventricular) pacing.
RESULTS: Compared with RV pacing, LV-based pacing significantly improved the indexes of LV systolic function (i.e., end-systolic pressure and volume, cardiac index, stroke work, preload recruitable stroke work, maximal rate of rise of LV pressure [dP/dtmax], LV ejection fraction, and end-systolic elastance). The LV diastolic filling indexes, end-diastolic pressure and volume, were better during LV-based pacing, whereas LV diastolic function indexes, –dP/dtmax, passive diastolic chamber stiffness, and time constant of LV isovolumic relaxation showed no clear change.
CONCLUSIONS: In the short term, LV-based pacing is superior to RV apical pacing in terms of contractile function and LV filling after AVJ ablation for drug-refractory AF.
|
Abbreviations and Acronyms
| | AF | = atrial fibrillation | | AVJ | = atrioventricular junction | | dP/dtmax | = maximal rate of rise in left ventricular pressure | | EDPVR | = end-diastolic pressure–volume relation | | LV | = left ventricle/ventricular | | PED | = end-diastolic pressure | | PES | = end-systolic pressure | | PRSW | = preload recruitable stroke work | | RV | = right ventricle/ventricular | | SW | = stroke work | | VED | = end-diastolic volume | | VES | = end-systolic volume |
|
Atrioventricular junction (AVJ) ablation and ventricular pacing have been proposed as alternative treatments for patients with chronic atrial fibrillation (AF) in whom the ventricular rate cannot be controlled with drugs. The usual way of pacing in such treatment is from the right ventricular (RV) apex, mainly because it is easy and provides high stability. Right ventricular apical stimulation, however, leads to asynchronous ventricular contraction, which results in a decrease in cardiac performance (1,2). This could counteract the beneficial hemodynamic effect of regularization of heart rhythm and could be the reason why cardiac performance does not improve after "ablate and pace" treatment (3).
In some recent studies, it was found that left ventricular (LV) free wall pacing or biventricular pacing is a useful treatment in patients with severe heart failure, not only for those in sinus rhythm but also for patients with AF after AVJ ablation (4–7). However, the exact mechanism through which this treatment improves cardiac performance in these patients has not yet been studied, nor has the effect of LV-based pacing in patients with normal systolic LV function and an intact His-Purkinje system.
In this short-term study, we evaluated the LV mechanics under RV apical and LV free wall and biventricular pacing after ablation of the AVJ because of drug-refractory AF. We hypothesized that the hemodynamics of LV-based pacing would be superior to those under RV apical pacing.
|
Methods
|
|---|
This study included 12 patients (5 men; mean age, 62 ± 8.3 years) who suffered from chronic AF with high ventricular response despite optimal treatment and where a clinical decision for AVJ ablation and pacing was made. In all cases, a biventricular pacing system was successfully implanted at least six weeks before the start of the study and was set to "off". The RV lead was implanted in the right ventricular apex in all cases, as it is the usual implantation site after His ablation. The target site for the LV lead was the mid-lateral cardiac vein. This was achieved in 10 patients, while in the remaining two patients the LV lead was implanted in the posterior cardiac vein.
According to the echocardiogram before the study, six patients had normal LV systolic function (i.e., LV ejection fraction  40%), while in the remaining six it was impaired due to non-ischemic dilated cardiomyopathy. After AVJ ablation, echocardiograms were obtained and analyzed blindly by the study-independent echocardiogram laboratory personnel of our clinic to evaluate mitral valve regurgitation under different pacing modes. Before AVJ ablation, all patients had a native narrow QRS complex, as measured on a 12-lead surface electrocardiogram (50 mm/s speed) (Table 1). There were five hypertensive and three diabetic patients in our group. Medication remained unchanged throughout the study and included warfarin (all patients), angiotensin-converting enzyme inhibitors (10 patients), beta-blockers (9 patients), diuretics (8 patients), digitalis (4 patients), calcium channel blockers (4 patients), insulin (2 patients), oral antidiabetic treatment (1 patient).
View this table:
[in this window]
[in a new window]
|
Table 1 Echocardiographically Calculated Individual Left Ventricular Dimensions, Ejection Fraction, QRS Duration, and Mitral Valve Regurgitation Before AVJ Ablation
|
|
All patients provided written, informed consent, and the experimental protocol was approved by the hospital ethics committee.
A short-term evaluation of left ventricular systolic and diastolic function was made 24 h after AVJ ablation, during routine coronary angiography, by pressure–volume relations obtained using the conductance catheter method during RV apical, LV free wall, and biventricular pacing.
The patients were alert, after an overnight fast, and were mildly sedated with diazepam orally on the day of evaluation. A conductance catheter (7F, Millar 572-7, Millar Instruments, Houston, Texas) was placed in the LV. For the production of pressure–volume curves under varying preload conditions, short-term preload reduction was achieved by transient occlusion of the inferior vena cava using a vascular occlusion balloon catheter (8F, STOPFLOW catheter system, PFM, Cologne, Germany). Pressure–volume loops for final analysis were obtained from a set of cardiac cycles during preload reduction, starting at the beat just before the onset of the LV pressure decline and ending with the nadir of the pressure decline, while any extrasystoles that occurred during the transient preload reduction were excluded from analysis. To eliminate respiratory effects on pressure–volume curves, all measurements were performed during suspended ventilation at end expiration.
In all patients a Swan-Ganz catheter was positioned in the pulmonary artery; cardiac output (thermodilution technique) and mean pulmonary capillary wedge pressure were monitored continuously throughout the study. Pressure–volume loops were derived after 5-min pacing for each of the three pacing types, in random order. The same pacing rate (75 beats/min) was used throughout the study. To ensure synchronous activation during biventricular pacing, the LV-RV delay was programmed to 10 ms, which was the shortest available in the pacemakers we used in our study. We used a special adapter (Leycom CFL 512, Cardiodynamics BV, Zoetermeer, the Netherlands) to digitize and store the signals from the conductance catheter and special software (CONDUCT2000, Cardiodynamics BV) for data analysis.
Ventricular preload was defined as VED, measured by averaging volumes during the mid-portion of isovolumic contraction for the steady state pressure–volume loop. Systolic pump function parameters included cardiac index, stroke volume, stroke work (SW) (calculated as the integral of the area of the pressure–volume loop and measured automatically by the analysis software), LV ejection fraction, end-systolic pressure (PES), and end-systolic volume (VES). Contractility change was assessed by four indexes: maximal rate of rise in LV pressure (dP/dtmax), slope of dP/dtmax to end-diastolic volume relation (dP/dtmax – VED), the slope of the SW-VED relation (PRSW), and the slope of the end-systolic pressure–volume relation line. The end-systolic pressure–volume relation line was determined from the set of pressure–volume points obtained at the end-systole (upper left corner of the pressure–volume loops) of 10 to 15 cardiac cycles before and immediately after mechanical obstruction of the inferior vena cava.
Diastolic performance parameters included VED, end-diastolic pressure (PED), negative dP/dtmax, end-diastolic pressure–volume relation (EDPVR), passive diastolic chamber stiffness (constant k), and the time constant of LV isovolumic relaxation. End-diastolic pressure–volume relation was determined similarly by the end-diastolic points of variably loaded pressure–volume loops produced by transient caval occlusion. The end-diastolic data were analyzed by exponential regression analysis to obtain the following equation: PED = PED V0 x exp (k x VEDS), where PEDV0 (mm Hg) is the LV end-diastolic pressure at zero volume and VEDS (ml) is the simultaneous LV end-diastolic volume. We defined the constant (k) (mm Hg/ml) in the equation as the passive diastolic chamber stiffness constant. The time constant was calculated by regressing LV pressure versus dP/dt during the isovolumic relaxation phase.
Statistics.
Summary data are given as mean ± SD. Because of the small number of patients, parametric tests were not performed, because we could not reliably test the assumptions required for a repeated measures analysis of variance. The non-parametric Friedman test was used to compare the distributions of the various parameters of interest under the three pacing types. P values <5% were the criterion for significance. In case of a significant finding, post hoc, Bonferroni adjusted for three comparisons, Wilcoxon tests were performed to pinpoint differences.
|
Results
|
|---|
Complete pressure–volume loop data sets were available from all patients. An example of pressure–volume loops obtained by transient occlusion of the inferior vena cava during three pacing modes is shown in Figure 1. Table 2 compares the values of systolic and diastolic performance under three types of pacing.
View larger version (21K):
[in this window]
[in a new window]
|
Figure 1 An example of pressure–volume loops obtained by transient occlusion of the inferior vena cava using a vascular occlusion balloon catheter during right ventricular apical (A), left ventricular free wall (B), and biventricular pacing (C) in one of our patients with normal left ventricular systolic function. The end-systolic pressure–volume relation line slope clearly increased during left ventricular free wall and biventricular pacing.
|
|
During LV-based pacing, load-dependent and load-independent indexes of contractile function improved in the short term, to a significant degree, compared with RV apical pacing (Table 2). The PES increased during LV-based pacing while VES decreased, both significantly, and this was represented by a leftward and upward shift of the end-systolic pressure–volume point in all patients (Fig. 2).
View larger version (10K):
[in this window]
[in a new window]
|
Figure 2 Signal-averaged data of left ventricular pressure–volume loops at baseline (before the beginning of the inflation of vascular occlusion balloon) during right ventricular apical (A), left ventricular free wall (B), and biventricular pacing (C) in the patient of Figure 1. Left ventricular–based pacing consistently shifted the end-systolic pressure–volume point upwards and to the left, and the end-diastolic pressure–volume point downwards and to the right. The area of the entire loop increased, indicating that left ventricular free wall and biventricular pacing produce a more effective contraction than does conventional right ventricular apical pacing.
|
|
For LV diastolic filling, VED increased in the short term, whereas the PED decreased, both significantly. Mean pulmonary capillary wedge pressure and V-wave amplitude decreased dramatically during LV free wall or biventricular pacing. In contrast, LV diastolic relaxation indexes did not change during LV-based pacing compared with RV apical pacing. The passive diastolic chamber stiffness did not change significantly, and the EDPVR slope showed no clear change (Table 2). There were no significant differences in any of the measured parameters between LV free wall and biventricular pacing.
Angiography confirmed that all patients had mitral valve regurgitation, which improved dramatically during LV-based pacing compared with RV apical pacing; semiquantitative mitral valve regurgitation score decreased from 2.8 ± 0.3 to 1.2 ± 0.6 (1 to 4 score scale). These findings were in line with previous echocardiographic evaluation under various pacing modes in our patients (Table 3).
View this table:
[in this window]
[in a new window]
|
Table 3 Echocardiographic Evaluation of Mitral Valve Regurgitation, Using the 1 (Mild) to 4 (Severe) Scale, at Various Pacing Modes and Consequent QRS Durations
|
|
|
Discussion
|
|---|
In this study we showed that LV-based pacing is superior to RV apical pacing in terms of LV contractile function and LV filling in patients with AF who had undergone AVJ ablation. In contrast, there were no significant differences in either systolic or diastolic function between LV free wall and biventricular pacing.
Biventricular or LV free wall pacing has already been examined in patients with AF and the "usual indications" for such pacing (i.e., dilated cardiomyopathy, severe heart failure, and interventricular conduction disturbances). Hemodynamics are improved in the short term during LV or biventricular pacing, regardless of whether the patients are in sinus rhythm or atrial fibrillation (4), while permanent biventricular pacing in such patients improves exercise tolerance (5). In a more recent study of patients with severe heart failure and RV apical pacing at least six months after AVJ ablation (6), upgrade to biventricular pacing was found to improve both LV function and symptoms. Finally, in the Multisite Stimulation in Cardiomyopathies Study (MUSTIC) study of patients with AF (7) biventricular pacing was found to increase exercise tolerance and to decrease the number of hospitalizations compared with VVIR pacing. The results of our study are consistent with those of the above clinical studies and provide the hemodynamic background to explain them.
Of particular importance is the fact that studying patients with AF is advantageous, because the impact of atrioventricular conduction can be eliminated as a complicating factor in the hemodynamic effects of LV-based pacing. Therefore, any changes in cardiac function during different modes of pacing may be attributed to a "pure" effect of pacing on LV function.
Furthermore, we included in our study consecutive patients with main criterion the indication for "ablate and pace" therapy. We selected the RV apex as the site of RV lead implantation as it is the usual position in this kind of therapy, in contrast with other studies where the RV lead site was chosen to be as far from the left lead as possible (7) or to ensure the shortest paced QRS duration (5). This difference, together with the shorter LV-RV delay in our study, could explain the absence of changes in QRS duration during biventricular compared with univentricular pacing from either ventricle in our patients.
Under these circumstances, we found that load-dependent and load-independent LV contractile function indexes were significantly improved in the short term during LV-based pacing compared with RV apical pacing. In contrast, indexes related to LV relaxation did not differ significantly between the three pacing types. However, VED was significantly higher and PED significantly lower during LV-based pacing, suggesting that the latter provides better LV diastolic filling. For patients in sinus rhythm with dilated cardiomyopathy and ventricular conduction disturbances, LV-based pacing has been found to improve mainly LV systolic function, causing only minimal changes in LV filling (8). However, in another study that included congestive heart failure patients, with or without left bundle branch block, the hemodynamic improvement by LV pacing was mainly attributed to an improvement in LV filling rather than ventricular systolic resynchronization (9).
Although we describe the short-term improvement in LV diastolic filling during LV-based pacing compared with RV apical pacing for the first time in humans, this has previously been observed in closed-chest dogs (10) and might be attributable to several factors. A significant reduction of mitral valve regurgitation, which comes in agreement with recent studies (11–16), was observed in all our patients and could be considered as one of these factors. Left ventricular–based pacing might improve the competence of mitral valve closure through better timing of the motion of its leaflets and of papillary muscle contraction, both of which are affected by the degree of the ventricular wall synchronous depolarization (10). Ventricular interaction during RV apical and LV-based pacing, reflected by altered septal motion, might also affect VED. Previous studies have demonstrated that the volume in one ventricle affects the volume in the other (17,18). Therefore, preexcitation of the LV during LV-based pacing could result in an earlier start of LV filling compared with that of the RV. Under these circumstances, LV filling might be greater, as it would take place before the development of external restraint from the stretched pericardium and the increased volume (and pressure) of the RV. A transient inward end-systolic wall motion, continued until early diastole, has previously been described during RV pacing (19). This represents a shortening of late-activated regional LV segments and reflects an area of delayed depolarization that may cause impaired diastolic filling and, hence, a smaller VED.
In the present study, we also confirm the observation made in animals that the sequence of electrical activation rather than the synchrony is more important to preserve LV function (20). Thus, despite the fact that QRS duration (representative of the degree of synchrony) was not significantly different between RV apical and LV-based pacing, LV function was superior under the latter type of pacing. This could be due to the different number of hypocontractible regions produced by each type of pacing; RV apical pacing has been found to generate a larger number of such regions within the LV wall compared with LV lateral wall pacing, which seems to ensure a more "physiological" activation sequence (20).
Study limitations.
In this study, we examined the short-term changes in LV mechanics during RV apical and LV-based pacing in patients with drug-refractory, chronic AF after AVJ ablation by means of pressure–volume relation analysis and hemodynamic evaluation. Under these conditions, no conclusions can be drawn about the long-term effects of permanent LV-based pacing in such patients. The size of the overall population included in our study was rather small. This was mainly because of the limited number of patients that met our inclusion criteria. In addition, our results should be interpreted in light of the hearts not being severely depressed, and it remains to be clarified whether this continues to apply in patients with severe systolic dysfunction.
Conclusions.
In terms of LV mechanics, LV-based pacing is superior to RV apical pacing in the short term in patients with permanent AF after AVJ ablation. More studies are required to evaluate the long-term results of these different types of pacing in such patients.
|
References
|
|---|
- Zile MR, Blaustein AS, Shimizu G, Gaasch WH. Right ventricular pacing reduces the rate of left ventricular relaxation and filling. J Am Coll Cardiol. 1987;10:702–709[Abstract]
- Vanderheyden M, Goethals M, Anguera I, et al. Hemodynamic deterioration following radiofrequency ablation of the atrioventricular conduction system. Pacing Clin Electrophysiol. 1997;20:2422–2428[CrossRef][Medline]
- Brignole M, Menozzi C, Gianfranchi L, et al. Assessment of atrioventricular junction ablation and VVIR pacemaker versus pharmacological treatment in patients with heart failure and chronic atrial fibrillation: A randomized, controlled study. Circulation. 1998;98:953–960[Abstract/Free Full Text]
- Etienne Y, Mansourati J, Gilard M, et al. Evaluation of left ventricular based pacing in patients with congestive heart failure and atrial fibrillation. Am J Cardiol. 1999;83:1138–1140[CrossRef][Medline]
- Leclercq C, Victor F, Alonso C, et al. Comparative effects of permanent biventricular pacing for refractory heart failure in patients with stable sinus rhythm or chronic atrial fibrillation. Am J Cardiol. 2000;85:1154–1156[CrossRef][Medline]
- Leon AR, Greenberg JM, Kanuru N, et al. Cardiac resynchronization in patients with congestive heart failure and chronic atrial fibrillation: Effect of upgrading to biventricular pacing after chronic right ventricular pacing. J Am Coll Cardiol. 2002;39:1258–1263[Free Full Text]
- Leclercq C, Walker S, Linde C, et al. Comparative effects of permanent biventricular and right-univentricular pacing in heart failure patients with chronic atrial fibrillation. Eur Heart J. 2002;23:1780–1787[Abstract/Free Full Text]
- Kass DA, Chen CH, Curry C, et al. Improved left ventricular mechanics from acute VDD pacing in patients with dilated cardiomyopathy and ventricular conduction delay. Circulation. 1999;99:1567–1573[Abstract/Free Full Text]
- Morris-Thurgood JA, Turner MS, Nightingale AK, et al. Pacing in heart failure: Improved ventricular interaction in diastole rather than systolic re-synchronization. Europace. 2000;2:271–275[Abstract/Free Full Text]
- Grover M, Glantz SA. Endocardial pacing site affects left ventricular end-diastolic volume and performance in the intact anesthetized dog. Circ Res. 1983;53:72–85[Abstract/Free Full Text]
- Yu CM, Fung WH, Lin H, et al. Predictors of left ventricular reverse remodeling after cardiac resynchronization therapy for heart failure secondary to idiopathic dilated or ischemic cardiomyopathy. Am J Cardiol. 2002;91:684–688
- Erol-Yilmaz A, Tukkie R, Schrama TA, et al. Reversed remodelling of dilated left sided cardiomyopathy after upgrading from VVIR to VVIR biventricular pacing. Europace. 2002;4:445–449[Abstract/Free Full Text]
- Gras D, Leclercq C, Tang AS, et al. Cardiac resynchronization therapy in advanced heart failure: The multicenter insync clinical study. Eur J Heart Fail. 2002;4:311–320[CrossRef][Medline]
- Yu CM, Chau E, Sanderson JE, et al. Tissue Doppler echocardiographic evidence of reverse remodeling and improved synchronicity by simultaneously delaying regional contraction after biventricular pacing therapy in heart failure. Circulation. 2002;105:438–445[Abstract/Free Full Text]
- Etienne Y, Mansourati J, Touiza A, et al. Evaluation of left ventricular function and mitral regurgitation during left ventricular-based pacing in patients with heart failure. Eur J Heart Fail. 2001;3:441–447[CrossRef][Medline]
- Kim WY, Sogaard P, Mortensen PT, et al. Three dimensional echocardiography documents haemodynamic improvement by biventricular pacing in patients with severe heart failure. Heart. 2001;85:514–520[Abstract/Free Full Text]
- Little WL, Reeves RC, Arciniegas J, et al. Mechanism of abnormal interventricular septal motion during delayed left ventricular activation. Circulation. 1982;65:1486–1491[Abstract/Free Full Text]
- Bove AA, Santamore WP. Ventricular interdependence. Prog Cardiovasc Dis. 1981;23:365–388[CrossRef][Medline]
- Badke FR, Boinay P, Covell JW. Effects of ventricular pacing on regional left ventricular performance in the dog. Am J Physiol. 1980;238:H858–H867
- Prinzen FW, Peschar M. Relation between pacing induced sequence of activation and left ventricular pump function in animals. Pacing Clin Electrophysiol. 2002;25:484–498[CrossRef][Medline]
This article has been cited by other articles:
|
|
|
|
 
N. M. Segerson, S. L. Wasmund, M. Daccarett, M. L. Fabela, C. H. Hammond, G. Stoddard, M. L. Smith, and M. H. Hamdan
The acute effect of atrioventricular pacing on sympathetic nerve activity in patients with normal and depressed left ventricular function
Am J Physiol Heart Circ Physiol,
September 1, 2008;
295(3):
H1076 - H1080.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
M. Gasparini, A. Auricchio, M. Metra, F. Regoli, C. Fantoni, B. Lamp, A. Curnis, J. Vogt, C. Klersy, and for the Multicentre Longitudinal Observational Stu
Long-term survival in patients undergoing cardiac resynchronization therapy: the importance of performing atrio-ventricular junction ablation in patients with permanent atrial fibrillation
Eur. Heart J.,
July 1, 2008;
29(13):
1644 - 1652.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
L. Johnson, H. K. Kim, M. Tanabe, J. Gorcsan, D. Schwartzman, S. G. Shroff, and M. R. Pinsky
Differential effects of left ventricular pacing sites in an acute canine model of contraction dyssynchrony
Am J Physiol Heart Circ Physiol,
November 1, 2007;
293(5):
H3046 - H3055.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
Authors/Task Force Members, P. E. Vardas, A. Auricchio, J.-J. Blanc, J.-C. Daubert, H. Drexler, H. Ector, M. Gasparini, C. Linde, F. B. Morgado, et al.
Guidelines for cardiac pacing and cardiac resynchronization therapy: The Task Force for Cardiac Pacing and Cardiac Resynchronization Therapy of the European Society of Cardiology. Developed in Collaboration with the European Heart Rhythm Association
Europace,
October 1, 2007;
9(10):
959 - 998.
[Full Text]
[PDF]
|
|
|
|
|
|
|
Authors/Task Force Members, P. E. Vardas, A. Auricchio, J.-J. Blanc, J.-C. Daubert, H. Drexler, H. Ector, M. Gasparini, C. Linde, F. B. Morgado, et al.
Guidelines for cardiac pacing and cardiac resynchronization therapy: The Task Force for Cardiac Pacing and Cardiac Resynchronization Therapy of the European Society of Cardiology. Developed in Collaboration with the European Heart Rhythm Association
Eur. Heart J.,
September 2, 2007;
28(18):
2256 - 2295.
[Full Text]
[PDF]
|
|
|
|
|
|
|
E. de Teresa, J. J. Gomez-Doblas, G. Lamas, J. Alzueta, I. Fernandez-Lozano, E. Cobo, X. Navarro, F. Navarro-Lopez, and M. Stockburger
Preventing ventricular dysfunction in pacemaker patients without advanced heart failure: rationale and design of the PREVENT-HF study
Europace,
June 1, 2007;
9(6):
442 - 446.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
R. Vatasescu, T. Shalganov, D. Paprika, L. Kornyei, Z. Prodan, G. Bodor, A. Szatmari, and T. Szili-Torok
Evolution of left ventricular function in paediatric patients with permanent right ventricular pacing for isolated congenital heart block: a medium term follow-up
Europace,
April 1, 2007;
9(4):
228 - 232.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
R. Lieberman, L. Padeletti, J. Schreuder, K. Jackson, A. Michelucci, A. Colella, W. Eastman, S. Valsecchi, and D. A. Hettrick
Ventricular Pacing Lead Location Alters Systemic Hemodynamics and Left Ventricular Function in Patients With and Without Reduced Ejection Fraction
J. Am. Coll. Cardiol.,
October 17, 2006;
48(8):
1634 - 1641.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
Writing Committee Members, V. Fuster, L. E. Ryden, D. S. Cannom, H. J. Crijns, A. B. Curtis, K. A. Ellenbogen, J. L. Halperin, J.-Y. Le Heuzey, G. N. Kay, et al.
ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation: full text: A report of the American College of Cardiology/American Heart Association Task Force on practice guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation) Developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society
Europace,
September 1, 2006;
8(9):
651 - 745.
[Full Text]
[PDF]
|
|
|
|
|
|
|
V. Fuster, L. E. Ryden, D. S. Cannom, H. J. Crijns, A. B. Curtis, K. A. Ellenbogen, J. L. Halperin, J.-Y. Le Heuzey, G. N. Kay, J. E. Lowe, et al.
ACC/AHA/ESC 2006 Guidelines for the Management of Patients With Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation) Developed in Collaboration With the European Heart Rhythm Association and the Heart Rhythm Society
J. Am. Coll. Cardiol.,
August 15, 2006;
48(4):
e149 - e246.
[Full Text]
[PDF]
|
|
|
|
|
|
|
M. Gasparini, A. Auricchio, F. Regoli, C. Fantoni, M. Kawabata, P. Galimberti, D. Pini, C. Ceriotti, E. Gronda, C. Klersy, et al.
Four-Year Efficacy of Cardiac Resynchronization Therapy on Exercise Tolerance and Disease Progression: The Importance of Performing Atrioventricular Junction Ablation in Patients With Atrial Fibrillation
J. Am. Coll. Cardiol.,
August 15, 2006;
48(4):
734 - 743.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
V. Fuster, L. E. Ryden, D. S. Cannom, H. J. Crijns, A. B. Curtis, K. A. Ellenbogen, J. L. Halperin, J.-Y. Le Heuzey, G. N. Kay, J. E. Lowe, et al.
ACC/AHA/ESC 2006 Guidelines for the Management of Patients With Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation): Developed in Collaboration With the European Heart Rhythm Association and the Heart Rhythm Society
Circulation,
August 15, 2006;
114(7):
e257 - e354.
[Full Text]
[PDF]
|
|
|
|
|
|
|
K. F. Kwaku
Cell Therapy for Rate Control in Atrial Fibrillation: A New Approach to an Old Problem
Circulation,
May 30, 2006;
113(21):
2474 - 2476.
[Full Text]
[PDF]
|
|
|
|
|
|
|
P Kies, C Leclercq, G B Bleeker, C Crocq, S G Molhoek, C Poulain, L van Erven, M Bootsma, K Zeppenfeld, E E van der Wall, et al.
Cardiac resynchronisation therapy in chronic atrial fibrillation: impact on left atrial size and reversal to sinus rhythm
Heart,
April 1, 2006;
92(4):
490 - 494.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
R. H. Falk
Rate Control Is Preferable to Rhythm Control in the Majority of Patients With Atrial Fibrillation
Circulation,
June 14, 2005;
111(23):
3141 - 3150.
[Full Text]
[PDF]
|
|
|
|
|
|
|
I. Hay, V. Melenovsky, B. J. Fetics, D. P. Judge, A. Kramer, J. Spinelli, C. Reister, D. A. Kass, and R. D. Berger
Short-Term Effects of Right-Left Heart Sequential Cardiac Resynchronization in Patients With Heart Failure, Chronic Atrial Fibrillation, and Atrioventricular Nodal Block
Circulation,
November 30, 2004;
110(22):
3404 - 3410.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
Top
Abstract
Methods