© 2004 by European Society of Cardiology
Copyright © 2003, The European Society of Cardiology
Right ventricular myocardial activation delay in adult patients with right bundle branch block late after repair of Tetralogy of Fallot
aDepartment of Cardiology, Second University of Naples, Naples, Italy
bDepartment of Cardiology, G. Rummo Hospital, Benevento, Italy
cDepartment of Cardiology, Monaldi Hospital, Naples, Italy
Received 22 January 2003; received in revised form 11 June 2003; accepted after revision 13 June 2003.
* Corresponding author. Via Martucci 35, 80121 Naples, Italy. Tel.: +39-081-643055; fax: +39-081-7145205. adandrea{at}synapsis.it
 |
Abstract |
|---|
 Top Abstract 1 Introduction2 Methods3 Results4 Discussion5 ConclusionsReferences |
|---|
Electromechanical interaction, with prolonged QRS duration due to right ventricular (RV) overload, has been described as a predictor of unfavorable outcome in patients late after correction of Tetralogy of Fallot (TOF). Aim of our study was to evaluate myocardial function and activation delay of both left and right ventricles in TOF patients. Doppler echo, treadmill test and pulsed Tissue Doppler (TD) were performed in 25 healthy subjects and in 30 adult patients who had undergone surgery for TOF, all with right bundle branch block on ECG. Exclusion criteria were evidence of residual pulmonary either stenosis or regurgitation. By use of TD, the level of both LV mitral and RV tricuspid annulus were measured: systolic (Sm), early- and late-diastolic (Em and Am) regional peak velocities. The indexes of myocardial systolic activation were calculated: precontraction time (PCTm) and interventricular activation delay (InterV-del) (difference of PCTm between RV and LV segments). The two groups were comparable for LV diameters and for Doppler indexes, while QRS duration was prolonged and RV end-diastolic diameter was increased in TOF. By TD analysis, only at the level of tricuspid annulus TOF patients had lower Sm and Em, and increased RV PCTm (p<0.001) and InterV-del (p<0.0001), even after adjustment for heart rate (HR) and QRS duration. By treadmill test, TOF showed reduced cardiac functional reserve. In seven patients non-sustained ventricular tachycardia was documented during physical effort. By multivariate analysis, RV Em (p<0.001), and InterV-del (p<0.01) were independently associated to maximal workload at peak effort. The same InterV-del was an independent determinant of risk of ventricular arrhythmias during effort (p<0.01). A cut-off point of Em peak velocity of tricuspid annulus <0.13 m/s at rest showed a sensitivity of 91% and a specificity of 88% in identifying TOF patients with submaximal exercise test. A cut-off point of InterV-del >55 ms showed 87% sensitivity and 88% specificity to detect increased risk of ventricular arrhythmias during effort. In TOF patients, TD analysis at rest may be taken into account as a non-invasive and easy-repeatable tool to predict cardiac performance during physical effort, and to select subgroups of patients at increased risk of ventricular arrhythmias.
Keywords: Tetralogy of Fallot; arrhythmias; tissue Doppler; diastole; right bundle branch block
|
1 Introduction |
|---|
|
TopAbstract1 Introduction2 Methods3 Results4 Discussion5 ConclusionsReferences |
|---|
Tetralogy of Fallot (TOF) is the most common form of cyanotic congenital heart disease. The current standard of its treatment is reparative operation in early infancy, with favorable long-term outcome in most patients.1,2
Electromechanical interaction, with prolonged QRS duration due to right ventricular (RV) overload, has been described as a predictor of malignant ventricular arrhythmias and of adverse prognosis in adult patients late after correction of TOF.3 In addition, in recent years interest has centered around the effects of the operation on RV diastolic function.4,5 In particular, restrictive RV diastolic dysfunction has been observed in a significant number of patients after repair of TOF.
Pulsed Tissue Doppler (TD) extends Doppler applications beyond the analysis of cardiac blood flows until the measurement of myocardial wall motion.6,7 TD patterns of myocardial function analyzes both systolic and diastolic regional peak velocities and time intervals, and have been used in several left ventricular (LV) pathologies. Our recent reports have shown TD usefulness to document also impairment of RV function in other cardiac diseases.8–12 However, few data are presently available about myocardial function in patients late after repair of TOF.13,14
On these grounds, aim of the present study was to assess by TD LV and RV myocardial function and myocardial activation delay of both left and right ventricles in TOF patients with right bundle branch block (RBBB) pattern on the surface ECG. In addition, we detected in these patients possible correlation between myocardial parameters at rest and cardiac response during physical effort.
|
2 Methods |
|---|
|
TopAbstract1 Introduction2 Methods3 Results4 Discussion5 ConclusionsReferences |
|---|
2.1 Study population
Thirty adult patients who had undergone surgery for TOF by one surgeon 18.2 ± 3.4 ago, and 25 healthy subjects, all with an RBBB pattern on the surface ECG, were enrolled after their informed consent and approval of the Ethic Committee of Monaldi Hospital was obtained.
The mean age at repair of TOF's patients was 1.4 ± 0.5. Four patients (13.3%) had previous palliations; only two patients (6.6%) had a transatrial repair. A transannular patch was used in two patients (6.6%), and a patch to infundibulum in four patients (13.3%).
Exclusion criteria for TOF patients were:
- – inability to perform a symptom-limited exercise stress by treadmill test;
- – any anamnestic, clinical and instrumental evidence of heart failure and of significant pulmonary regurgitation (regurgitant fraction >40%) or RV outflow tract obstruction (transvalvular gradient >20 mmHg), and of severe tricuspid regurgitation;
- – abnormal lung function assessed by chest X-ray film, spirometry, and blood gas analysis;
- – treatment with cardioactive drugs (digitalis, beta-blockers, calcium channel blockers, antiarrhythmics).
- – any anamnestic, clinical and instrumental evidence of heart failure and of significant pulmonary regurgitation (regurgitant fraction >40%) or RV outflow tract obstruction (transvalvular gradient >20 mmHg), and of severe tricuspid regurgitation;
Exclusion criteria for patients of the control group were: coronary artery disease, valvular and congenital heart disease, congestive heart failure, cardiomyopathies, diabetes mellitus, echocardiograms of inadequate quality.
All the subjects of the study were involved in regular moderate physical exercise. In particular, they performed 2 h/week of low-intensity running (with heart rate (HR) maintained on 60–70% of HR reserve), and only 1 h/week of weight-lifting at low workload.
2.2 Methods
Standard ECG, Doppler echocardiography and TD were performed by Acuson Sequoia machine (Mountain View, CA, U.S.A.) equipped with TD capabilities. A variable frequency phased-array transducer (2.5–3.5–4.0 MHz) was used for echo-Doppler and TD imaging. All the measurements were analyzed by two experienced readers, by the average of three to five cardiac cycles. M-mode measurements were performed according to the American Society of Echocardiography in parasternal long-axis view.15 LV ejection fraction was calculated by Simpson's rule technique and LV stroke volume was obtained as the difference between end-diastolic and end-systolic volumes. RV internal long-axis length and tricuspid valve ring diameter were measured in the four-chamber view at end-diastole, according to the protocol of Foale et al.16 The apical four-chamber view was also recorded to measure tricuspid annular plane systolic excursion (TAPSE) as index of RV global systolic function.17 Pulsed Doppler LV and RV inflow recordings were performed in apical four-chamber view, by placing sample volume at the tips level. E and A peak velocities (m/s) and their ratio, E wave deceleration time (ms), isovolumic relaxation time were measured as indexes of LV and RV global diastolic function. RV myocardial performance index was calculated by the following formula: (A–B)/B, where A was the time interval between cessation and onset of tricuspid inflow, and B was pulmonary ejection time.18
Pulsed TD was performed by spectral pulsed Doppler signal filters, adjusting Nyquist limit until 15–20 cm/s (close to myocardial velocities).6,7 In apical four-chamber view, a 5 mm pulsed Doppler sample volume was placed at the level of both LV mitral annulus and RV tricuspid annulus. The apical view was chosen to obtain quantitative assessment of regional wall motion almost simultaneous to Doppler LV and RV inflow and to minimize the incidence angle between Doppler beam and longitudinal wall motion. Pulsed TD of both mitral and tricuspid annulus is characterized by a myocardial systolic wave (Sm) and two diastolic waves—early (Em) and atrial (Am) (Fig. 1). Myocardial peak velocity of Sm (m/s) and contraction time (from the beginning to the end of Sm wave) (all in ms) were calculated as systolic indexes. Myocardial early (Em) and atrial (Am) peak velocities (m/s) and Em/Am ratio, and regional relaxation time (RTm) (ms)—as the time interval occurring between the end of Sm and the onset of Em—were determined as diastolic measurements. As indexes of myocardial systolic activation was calculated: precontraction time (PCTm) (from the beginning of Q wave of ECG to the onset of Sm) and interventricular activation delay (InterV-del) (difference between PCTm of RV tricuspid annulus and PCTm of LV mitral annulus).8–12 Reproducibility of measuring the main TD parameters was determined in 18 subjects (10 TOF and eight controls), according to previously reported methods. Inter- and intraobserver variability was examined using Bland–Altman analysis.
|
2.3 Exercise stress test
All the patients underwent exercise stress test by treadmill with standard Bruce protocol.2,19 The test was terminated if one of the following endpoints was reached: target HR, severe fatigue, severe dyspnea, severe ventricular arrhythmias. The following functional indexes were assessed at peak effort: maximal HR, maximal systolic blood pressure (SBP), rate–pressure product (maximal HR x maximal SBP), maximal workload (number of METS achieved by treadmill test), and time duration of the exercise.
2.4 Statistical methods
The analyses were performed by SPSS for Windows release 11.0 (Chicago, IL, U.S.A.). Variables are presented as mean±SD. t-Test for unpaired data estimated differences between the two groups. Linear regression analyses and partial correlation test by either Pearson's or Spearman's method were done to assess univariate relations. Stepwise, forwards, multiple either regression analyses or logistic regression analyses were performed to weigh the independent effects of potential determinants on a dependent variable. Differences were significant at p<0.05.
|
3 Results |
|---|
|
TopAbstract1 Introduction2 Methods3 Results4 Discussion5 ConclusionsReferences |
|---|
3.1 Clinical characteristics of the study population
The two groups were comparable for age (22.4±3.8 in TOF patients vs 21.9±3.3 years in controls), sex (17/30 male in TOF vs 14/25 in controls), body surface area (1.86±0.11 in TOF vs 1.84±0.08 m2 in controls), HR (77.9±11.9 in TOF vs 79.1 ± 3.4 b/m in controls) and both systolic (118.6±9.3 in TOF vs 119.7 ± 5.8 in controls) and diastolic BP (76.7±5.1 in TOF vs 79.8 ± 4 mmHg in controls). On the surface ECG all the patients were in sinus rhythm and had an RBBB. There was a significant difference in the QRS duration of the resting ECG between the two groups ((141.3 ± 18 ms in TOF vs 110.3 ± 10 ms in controls; p<0.01).
3.2 Standard Doppler echocardiographic analysis
By standard echo analysis, TOF patients had significantly reduced LV stroke volume and greater RV internal long-axis length and tricuspid valve ring diameter. Conversely, LV internal diameters, LV ejection fraction and TAPSE were comparable between the two groups. As for Doppler measurements, both mitral and tricuspid peak velocity E/A ratios as well as time intervals were similar between the two groups, while RV MPI was prolonged in TOF patients (Table 1).
|
3.3 Pulsed TD analysis
Despite the presence of RBBB on surface ECG, patients of the control group showed homogeneous systolic activation of both myocardial segments. Conversely, at the level of tricuspid annulus TOF patients showed prolonged PCTm (p<0.001) and significant systolic dyssynchrony, with increased InterV-del (p<0.0001). Also RV tricuspid Sm, Em and Em/Am ratio were reduced and RTm prolonged in TOF patients (Table 2). These differences remained significant even after adjustment for HR and QRS duration. Conversely, no significant differences between the two groups at LV mitral annulus level were found except a reduced Em/Am ratio (p<0.01). Interobserver variability was ±2.8% for Sm peak velocities, ±3.9% for Em peak velocities, ±4.1% for PCTm, ±4.6% for COm. Intraobserver variability was similar: ±2.9% for Sm peak velocities, ±4.1% for Em peak velocities, ±4.6% for PCTm, ±4.8% for COm.
|
3.4 Treadmill test
During physical effort, TOF patients showed reduced functional capacity, with lower rate–pressure product, maximal workload and time duration of exercise than controls (Table 3). Of note, the exercise test was submaximal (maximal HR lower than target HR) in 12/30 (40%) patients in the TOF group, and only in five of the 25 controls (20%) (p<0.001). In seven TOF patients (23.3%) non-sustained episodes of ventricular tachycardia (stopping spontaneously in less than 30 s) were documented during physical effort. In all these patients with arrhythmias during effort, non-sustained ventricular tachycardia was confirmed by 24-h Holter ECG monitoring.
|
3.5 Univariate relations of TD indexes
In TOF patients, RV Em was significantly related to maximal workload during effort (r = 0.72; p<0.0001) and time duration of exercise (r = 0.63; p<0.001). Moreover, a significant inverse relation was observed between maximal workload during effort and InterV-del (r = –0.52; p<0.01) (Fig. 2).
|
3.6 Multivariate analysis
Stepwise forward, multiple linear regression separate analyses were performed in the TOF group to weigh the independent associations between RV myocardial indexes and functional parameters during effort. By this model, after adjusting for potential determinants as age at follow-up, age at surgery, use of transannular patch, HR, QRS duration, and diastolic diameters, only RV tricuspid valve ring diameter (β = –0.45; p<0.001), RV Em (standardized β coefficient=0.66; p<0.001), and InterV-del (β = –0.35; p<0.01) were independently associated to maximal workload at peak effort (cumulative R2=0.72; p<0.00001). Furthermore, by multivariate logistic regression analysis, the same InterV-del was an independent determinant of increased risk of ventricular arrhythmias during physical effort (OR=4.6; CI=1.3–6.4; p<0.01).
3.7 Sensitivity and specificity of TD
By receiver operating characteristic (ROC) curve analysis, a cut-off point of Em peak velocity of tricuspid annulus <0.13 m/s at rest showed a sensitivity of 91% and a specificity of 88% in identifying TOF patients unable to perform maximal exercise test. On the other hand, a cut-off point of InterV-del >55 ms showed 87% sensitivity and 88% specificity to detect increased risk of ventricular arrhythmias during effort (Fig. 3).
|
|
4 Discussion |
|---|
|
TopAbstract1 Introduction2 Methods3 Results4 Discussion5 ConclusionsReferences |
|---|
Most of the problems reported during the late follow-up of patients after repair of TOF has been related to abnormal RV physiology. Residual pulmonary incompetence, exercise intolerance and malignant ventricular arrhythmias have been identified as predictors of unfavorable long-term outcome.1,2
The present study demonstrates the usefulness of pulsed TD to evaluate myocardial pattern of right ventricle in adult patients late after repair of TOF. The main findings are that, by TD analysis, TOF patients show: (1) lower myocardial peak velocities and prolonged time intervals only at the level of RV tricuspid annulus and (2) impaired interventricular systolic synchronicity, due to delayed activation of RV lateral wall, independently of resting HR and QRS duration.
4.1 TD myocardial function in TOF patients
While several reports described pulsed TD pattern in LV diseases,6–8 little is known about RV TD changes due to RV pathologies.8–14 To the best of our knowledge, this is the first attempt to correlate RV myocardial function and cardiac performance during effort in TOF patients by this technique. In agreement with recent reports, RV myocardial systolic and early-diastolic peak velocities were decreased and Em/Am ratio reduced in TOF patients at the level of RV tricuspid annulus.13,14 An additional finding of our study is, however, the evidence of a prolongation of PCTm only at the level of tricuspid annulus, with consequent delay in activation of RV ventricular wall in TOF patients with RBBB. Of interest, experimental studies have reported that right ventricle, unlike left ventricle, begins to eject after a minimal isovolumic systolic contraction time, and starts its diastolic filling without an isovolumic relaxation interval, since works against lower vascular impedance.20 However, a prolongation of isovolumic contraction and relaxation times occurs in all pathologic conditions involving right ventricle, in relation to either increasing pulmonary load or RV intrinsic myocardial dysfunction.21
4.2 Association between myocardial function at rest and cardiac performance during effort
Our results emphasize, in a selected population of TOF patients without echocardiographic evidence of residual significant either pulmonary regurgitation or stenosis, a close link between RV myocardial systolic and diastolic properties and cardiac performance during effort.
Recent studies suggested that, in absence of significant lung function abnormalities and severe hemodynamic embalancement, the impaired exercise performance of adult TOF patients may be related to abnormalities of RV compliance secondary to endomyocardial fibrosis.22 In addition, RV myocardial hypertrophy, alone or in combination with the superimposition of the effects of cardiopulmonary by-pass, ventriculotomy, inadequate myocardial protection, and the placement of nonfunctional patches, may further impair RV diastolic function.4,5
Previous authors evidenced a strong inverse relation of TD early-diastolic velocities to the amount of the interstitial fibrosis assessed by transmural endomyocardial biopsy.23 In addition, in our experience we have found a prolongation of myocardial contractility and relaxation times and a reduction of RV myocardial peak velocities in several pathologic conditions involving right ventricle, in relation to either increasing pulmonary load or RV intrinsic myocardial dysfunction.10–12 Since Em peak velocity is expression of myocardial diastolic properties of the ventricles, its decrease in TOF patients at a tricuspid annulus level may indicate an impairment of RV myocardial diastolic function. It is reasonable to suppose that such reduced early-diastolic stretching of myocardial fibers of the right ventricle (i.e. Em peak) may determine in its turn reduced RV myocardial systolic performance by a worse utilization of Frank–Starling mechanism, and the consequent impaired cardiac response during physical effort in the TOF group.
4.3 RV myocardial activation delay and ventricular arrhythmias
By our findings, the impairment of interventricular systolic synchronicity in TOF patients with RBBB is strongly related to increased risk of ventricular arrhythmias during effort. It should be emphasized that TOF represents an important model for electromechanical interactions, because it is a nonischemic dilated model with myocardial scarring.3 There is good evidence from previous electrophysiological studies that ventricular tachycardia, in this setting, results from reentry.24 A QRS duration on the resting ECG >180 ms has been described as a sensitive predictor of life-threatening arrhythmias.3 Moreover, fragmented electrograms and increased QT dispersion, indicative of localized areas of slowed conduction, have been recorded in different areas of the right ventricle.25 Finally, ventriculotomy scar, ventricular septal defect and outflow patch have been each implicated as areas of potential block within the reentry circuit.24 Such anatomical and electrical substrate may on one hand determine a regional delay in systolic activation of RV ventricular wall, with consequent prolongation of InterV-del, and on the other hand establish single macroscopic or multiple microscopic reentrant circuits, generating monomorphic or polymorphic ventricular tachycardias.
4.4 Study limitations
Our population represents a very selected group of survivors of early surgical repair of TOF. In fact, in order to assess the effect of RV diastolic dysfunction, we did not include subjects with evidence of significant pulmonary regurgitation or RV outflow tract obstruction and of abnormal lung function.
In our study protocol we did not include the assessment of maximal oxygen uptake (the most reliable measure of exercise capacity), transmural endomyocardial biopsy or electrophysiological study. However, we performed by treadmill test an extensive analysis of all the functional parameters usually measured during the routine evaluation of work capacity of adult TOF patients.1,2 Furthermore, previous reports have well-documented by endomyocardial biopsy the presence of RV endomyocardial fibrosis in TOF patients.22
|
5 Conclusions |
|---|
|
TopAbstract1 Introduction2 Methods3 Results4 Discussion5 ConclusionsReferences |
|---|
In adult patients late after surgical repair of TOF, pulsed TD analysis may be taken into account as an effective, non-invasive and easy-repeatable supporting tool both to evaluate RV myocardial function at rest and to predict cardiac performance during physical effort.
In addition, such technique may be also useful to select subgroups of TOF patients at increased risk of ventricular arrhythmias that may benefit from prophylactic antiarrhythmic therapy and electrophysiological study during long-term follow-up.
|
Acknowledgements |
|---|
This paper is supported by Ph. Doctorate in Medical–Surgical Physiopathology of Cardiopulmunar and Respiratory System and Associated Biotechnologies Second University of Naples (Italy).
|
References |
|---|
|
TopAbstract1 Introduction2 Methods3 Results4 Discussion5 ConclusionsReferences |
|---|
- Swan L., Hillis W.S. Exercise prescription in adults with congenital heart disease: a long way to go. Heart (2000) 83:685–687.
[Abstract/Free Full Text] - Sarubbi B., Pacileo G., Pisacane C., et al. Exercise capacity in young patients after total repair of Tetralogy of Fallot. Pediatr Cardiol (2000) 21:211–215.[CrossRef][Web of Science][Medline]
- Gatzoulis M.A., Till J.A., Sommerville J., et al. Electromechanical interaction in Tetralogy of Fallot. QRS prolongation relates to right ventricular size and predicts malignant ventricular arrhythmias and sudden death. Circulation (1995) 92:231–237.
[Abstract/Free Full Text] - Gatzoulis M.A., Clark A.L., Cullen S., et al. Right ventricular diastolic function 15 to 35 years after repair of Tetralogy of Fallot. Circulation (1995) 91:1775–1781.
[Abstract/Free Full Text] - Munkhammar P., Cullen S., Jogi P., et al. Early age at repair prevents restrictive right ventricular (RV) physiology after surgery for Tetralogy of Fallot (TOF): diastolic RV function after TOF repair in infancy. J Am Coll Cardiol (1999) 34:1657–1658.
[Free Full Text] - Isaaz K., Thompson A., Ethevenot G., et al. Doppler echocardiographic measurement of low velocity motion of the left ventricular posterior wall. Am J Cardiol (1989) 64:66–75.[CrossRef][Web of Science][Medline]
- Garcia Fernandez M.A., Azevedo J., Moreno M., et al. Regional diastolic function in ischaemic heart disease using pulsed wave Doppler Tissue Imaging. Eur Heart J (1999) 20(7):496–507.
[Abstract/Free Full Text] - D'Andrea A., Caso P., Galderisi M., et al. Assessment of myocardial response to physical exercise in endurance competitive athletes by pulsed Doppler tissue imaging. Am J Cardiol (2001) 87:1226–1230.[CrossRef][Web of Science][Medline]
- D'Andrea A., Caso P., Galderisi M., et al. Ventricular interdependence in patients with dual-chamber pacing: a Doppler tissue imaging study. Echocardiography (2002) 19:289–297.[CrossRef][Web of Science][Medline]
- D'Andrea A, Caso P, Sarubbi B, et al. Right ventricular myocardial dysfunction in adult patients late after repair of Tetralogy of Fallot. Int J Cardiol 2003, in press.
- D'Andrea A., Caso P., Severino S., et al. Different involvement of right ventricular myocardial function in either physiological or pathological left ventricular hypertrophy: a tissue Doppler study. J Am Soc Echocardiogr (2003) 16:154–161.[CrossRef][Web of Science][Medline]
- Caso P., Galderisi M., Cicala S., et al. Association between right ventricular relaxation time and pulmonary arterial pressure in chronic obstructive lung disease: analysis by pulsed Doppler tissue imaging. J Am Soc Echocardiogr (2001) 14:970–977.[CrossRef][Web of Science][Medline]
- Vogel M., Sponring J., Cullen S., et al. Regional wall motion and abnormalities of electrical depolarization and repolarization in patients after surgical repair of Tetralogy of Fallot. Circulation (2001) 103:1669–1673.
[Abstract/Free Full Text] - Weidemann F., Eyskens B., Mertens L., et al. Quantification of regional right and left ventricular function by ultrasonic strain rate and strain indexes after surgical repair of Tetralogy of Fallot. Am J Cardiol (2002) 15:133–138.[CrossRef]
- Sahn D.J., De Maria A., Kisslo J., Weyman A., for The Committee on M-mode Standardization of the American Society of Echocardiography. Recommendations regarding quantitation in M-mode echocardiography: results of a survey of echocardiographic measurements. Circulation (1978) 58:1072–1083.
[Abstract/Free Full Text] - Foale R.A., Nihoyannopoulos P., Mc Kenna W. Echocardiographic measurement of normal adult right ventricle. Br Heart J (1986) 56:33–44.
[Abstract/Free Full Text] - Kaul S., Tei C., Hopkins J.M., et al. Assessment of right ventricular function using two dimensional echocardiography. Am Heart J (1984) 128:301–307.[CrossRef]
- Moller J.E., Poulsen S.H., Egstrup K. Effect of preload alternations on a new Doppler echocardiographic index of combined left ventricular systolic and diastolic performance. J Am Soc Echocardiogr (1999) 135:1065–1072.
- Fletcher G.F., Balady G., Froelicher V.F., et al. Exercise standards. A statement for healthcare professionals from the American Heart Association. Circulation (1995) 91:580–588.
[Free Full Text] - Myhre E.S., Slinker B.K., LeWinter M.M. Absence of right ventricular isovolumic relaxation in open-chest anaesthetized dogs. Am J Physiol (1992) 263:587–590.
- Santamore W.P., Dell'Italia L.J. Ventricular interdependence: significant left ventricular contributions to right ventricular function. Prog Cardiovasc Dis (1998) 40:289–308.[CrossRef][Web of Science][Medline]
- Hegarty A., Anderson R.H., Deanfield J.E. Myocardial fibrosis in Tetralogy of Fallot: effect of surgery or part of natural history? Br Heart J (1988) 59:123–126.
- Shan K., Bick R.J., Poindexter B.J., et al. Relation of tissue Doppler derived myocardial velocities to myocardial structure and beta-adrenergic receptor density in humans. J Am Coll Cardiol (2000) 36:891–896.
[Abstract/Free Full Text] - Garson A., Porter C.J., Gilette P.C., et al. Induction of ventricular tachycardia during electrophysiologic study after repair of Tetralogy of Fallot. J Am Coll Cardiol (1985) 5:134B–137B.[Medline]
- Deanfield J.E., McKenna W., Rowland E. Local abnormalities of right ventricular depolarization after repair of Tetralogy of Fallot: a basis for ventricular arrhythmia. Am J Cardiol (1985) 55:522–525.[CrossRef][Web of Science][Medline]
CiteULike 
Connotea 
Del.icio.us What's this?
Related articles in Eur J Echocardiogr:
- Right ventricular function: the comeback of echocardiography?
- Willem A Helbing
Eur J Echocardiogr 2004 5: 99-101.[Extract] [Full Text]
This article has been cited by other articles:
|
|
 |
|
  M. K. Friedberg and L. Mertens Tissue velocities, strain, and strain rate for echocardiographic assessment of ventricular function in congenital heart disease Eur J Echocardiogr, July 1, 2009; 10(5): 585 - 593. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Rosianu, D. Paprika, I. Osztheimer, A. Temesvari, and T. Szili-Torok Echocardiographic evaluation of patients with undocumented arrhythmias occurring in adults late after repair of tetralogy of Fallot Eur J Echocardiogr, January 1, 2009; 10(1): 139 - 143. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Urashima, M. Zhao, R. Wagner, G. Fajardo, S. Farahani, T. Quertermous, and D. Bernstein Molecular and physiological characterization of RV remodeling in a murine model of pulmonary stenosis Am J Physiol Heart Circ Physiol, September 1, 2008; 295(3): H1351 - H1368. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Brechot, L. Gambotti, S. Lafitte, and R. Roudaut Usefulness of right ventricular isovolumic relaxation time in predicting systolic pulmonary artery pressure Eur J Echocardiogr, July 1, 2008; 9(4): 547 - 554. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J.-J. Ge, X.-G. Shi, R.-Y. Zhou, M. Lin, S.-L. Ge, and S.-B. Zhang Right Ventricular Dysfunction Due to Right Ventricular Outflow Tract Patch Asian Cardiovasc Thorac Ann, June 1, 2006; 14(3): 213 - 218. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. D'Andrea, P. Caso, S. Severino, S. Cuomo, G. Capozzi, P. Calabro, G. Cice, L. Ascione, M. Scherillo, and R. Calabro Prognostic value of intra-left ventricular electromechanical asynchrony in patients with hypertrophic cardiomyopathy Eur. Heart J., June 1, 2006; 27(11): 1311 - 1318. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G.-P. Diller, D. Okonko, A. Uebing, S. Y. Ho, and M. A. Gatzoulis Cardiac resynchronization therapy for adult congenital heart disease patients with a systemic right ventricle: analysis of feasibility and review of early experience. Europace, April 1, 2006; 8(4): 267 - 272. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A D'Andrea, P Caso, S Cuomo, G Salerno, R Scarafile, C Mita, G De Corato, B Sarubbi, M Scherillo, R Calabro, et al. Prognostic value of intra-left ventricular electromechanical asynchrony in patients with mild hypertrophic cardiomyopathy compared with power athletes * Commentary. Br. J. Sports Med., March 1, 2006; 40(3): 244 - 250. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. D'Andrea, S. Stisi, S. Bellissimo, F. Vigorito, F. Scotto di Uccio, N. Tozzi, F. Moscato, E. Pezzullo, R. Calabro, and M. Scherillo Early impairment of myocardial function in systemic sclerosis: Non-invasive assessment by Doppler myocardial and strain rate imaging Eur J Echocardiogr, December 1, 2005; 6(6): 407 - 418. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. A Helbing Right ventricular function: the comeback of echocardiography? Eur J Echocardiogr, March 1, 2004; 5(2): 99 - 101. [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||