Effect of pulmonary regurgitation on cardiac functions based on a human bi-ventricle model.

BACKGROUND AND OBJECTIVE: Assessing the severity of pulmonary regurgitation (PR) and identifying optimal clinically relevant indicators for its treatment is crucial, yet standards for quantifying PR remain unclear in clinical practice. Computational modelling of the heart is in the process of providing valuable insights and information for cardiovascular physiology research. However, the advancements of finite element computational models have not been widely applied to simulate cardiac outputs in patients with PR. Furthermore, a computational model that incorporates both the left ventricle (LV) and right ventricle (RV) can be valuable in assessing the relationship between left and right ventricular morphometry and septal motion in PR patients. To enhance our understanding of the effect of PR on cardiac functions and mechanical behaviour, we developed a human bi-ventricle model to simulate five cases with varying degrees of PR severity. METHODS: This bi-ventricle model was built using a patient-specific geometry and a widely used myofibre architecture. The myocardial material properties were described by a hyperelastic passive constitutive law and a modified time-varying elastance active tension model. To simulate realistic cardiac functions and the dysfunction of the pulmonary valve in PR disease cases, open-loop lumped parameter models representing systemic and pulmonary circulatory systems were designed. RESULTS: In the baseline case, pressures in the aorta and main pulmonary artery and ejection fractions of both the LV and RV were within normal physiological ranges reported in the literature. The end-diastolic volume (EDV) of the RV under varying degrees of PR was comparable to the reported cardiac magnetic resonance imaging data. Moreover, RV dilation and interventricular septum motion from the baseline to the PR cases were clearly observed through the long-axis and short-axis views of the bi-ventricle geometry. The RV EDV in the severe PR case increased by 50.3% compared to the baseline case, while the LV EDV decreased by 18.1%. The motion of the interventricular septum was consistent with the literature. Furthermore, ejection fractions of both the LV and RV decreased as PR became severe, with LV ejection fraction decreasing from 60.5% at baseline to 56.3% in the severe case and RV ejection fraction decreasing from 51.8% to 46.8%. Additionally, the average myofibre stress of the RV wall at end-diastole significantly increased due to PR, from 2.7±12.1 kPa at baseline to 10.9±26.5 kPa in the severe case. The average myofibre stress of the LV wall at end-diastole increased from 3.7±18.1 kPa to 4.3±20.3 kPa. CONCLUSIONS: This study established a foundation for the computational modelling of PR. The simulated results showed that severe PR leads to reduced cardiac outputs in both the LV and RV, clearly observable septum motion, and a significant increase in the average myofibre stress in the RV wall. These findings demonstrate the potential of the model for further exploration of PR.

Minimally Invasive Pulmonary Fibroelastoma Resection.

Pulmonary fibroelastomas are a rare primary cardiac tumor with less than 50 cases reported in the literature to date. We performed a minimally invasive valve-sparing tumor resection through a left anterior mini-incision (LAMI). The procedure was performed without cardiac arrest or aortic cross clamp, expediting postoperative recovery and allowing for an uncomplicated discharge on postoperative day 5. LAMI is a safe and reliable alternative to median sternotomy for patients requiring interventions on the right ventricular outflow tract and main pulmonary artery, including pulmonary fibroelastoma resection and pulmonary valve replacement when needed.

One-Year Follow-up After Tetralogy of Fallot Total Repair Preserving Pulmonary Valve and Avoiding Right Ventriculotomy.

BACKGROUND: We reviewed our revised surgical strategy for tetralogy of Fallot (TOF) total correction to minimize early exposure to significant pulmonary regurgitation (PR) and to avoid right ventriculotomy (RV-tomy). Methods and Results: Since February 2016, we have tried to preserve, first, pulmonary valve (PV) function to minimize PR by extensive commissurotomy with annulus saving; and second, RV infundibular function by avoiding RV-tomy. With this strategy, we performed total correction for 50 consecutive patients with TOF until May 2018. We reviewed the early outcomes of 27 of 50 patients who received follow-up for ≥3 months. Mean patient age at operation was 10.2±5.0 months, and mean body weight was 8.8±1.2 kg. The preoperative pressure gradient at the RV outflow tract and the PV z-score were improved at most recent echocardiography from 82.0±7.1 to 26.8±6.4 mmHg, and from -2.35±0.49 to -0.55±0.54, respectively, during 11.1±1.6 months of follow-up after operation. One patient required re-intervention for residual pulmonary stenosis. Twenty-two patients had less than moderate PR (none, 1; trivial, 8; mild, 13), and 5 patients had moderate PR. There was no free or severe PR. CONCLUSIONS: At 1-year follow-up, the patients who underwent total TOF correction with our revised surgical strategy had acceptable results in terms of PV function. The preserved PV had a tendency to grow on short-term follow-up.

Three-dimensional analysis of regional right ventricular shape and function in repaired tetralogy of Fallot using cardiovascular magnetic resonance.

BACKGROUND: Patients with surgically repaired tetralogy of Fallot (rTOF) often have residual pulmonic valve regurgitation, leading to abnormal remodeling and dysfunction of the right ventricle often requiring pulmonic valve replacement. We tested the hypothesis that 3D analysis of right ventricular (RV) shape and function may reveal differences in regional adaptive remodeling that occurs in patients with rTOF, depending on whether a transannular patch (TAP) was utilized. METHODS: Forty patients with rTOF who underwent cardiac magnetic resonance imaging (1.5 T), including 20 with and 20 without TAP, and 10 normal controls were studied. Images were analyzed to measure RV endocardial curvature and global and regional volume and function. RESULTS: RV ejection fraction (EF) was 42 ±â€¯11% in TAP and 38 ±â€¯9% in no-TAP (p = 0.19), both lower than 54 ±â€¯3% in controls (p < 0.01). Left ventricular (LV) EF was 54 ±â€¯9% in TAP, 54 ±â€¯8% in no-TAP (p = 0.87) and 61 ±â€¯16% in controls (both p < 0.01). Indexed LV end-diastolic volumes were higher in no-TAP than in TAP subgroup (p = 0.02). With TAP, mid RV septum showed lower curvature during diastole (less convex), than the mid and apical free walls and free wall adjacent to the RV outflow tract (RVOT; more convex). There were no differences in curvature during systole between rTOF subgroups but mid and RVOT free walls showed higher curvature versus controls. CONCLUSIONS: This is the first study to comprehensively describe the influence of TAP on changes in regional RV shape in patients with rTOF. Understanding these differences may help guide therapeutic options for residual pulmonary valve regurgitation in rTOF patients.

Carcinoid Valve Disease: A Case Report and Review.

In patients with carcinoid syndrome, the development of carcinoid valve disease typically carries an unfavorable prognosis. We present the case of a patient with significant valvular dysfunction secondary to carcinoid valve disease. Valve replacement surgery was complicated by the development of prosthetic valve degeneration, ultimately requiring percutaneous valve implantation in a valve-in-valve fashion. The technical details of the case, as well as a review of carcinoid valve disease, including its pathophysiology, clinical manifestations, diagnostic features and management considerations, are presented.

Isolated pulmonary regurgitation causes decreased right ventricular longitudinal function and compensatory increased septal pumping in a porcine model.

AIM: Longitudinal ventricular contraction is a parameter of cardiac performance with predictive power. Right ventricular (RV) longitudinal function is impaired in patients with free pulmonary regurgitation (PR) following corrective surgery for Tetralogy of Fallot (TOF). It remains unclear whether this is a consequence of the surgical repair, or whether it is inherent to PR. The aim of this study was to assess the relationship between longitudinal, lateral and septal pumping in a porcine model of isolated PR. METHODS: Piglets were divided into a control (n = 8) group and a treatment (n = 12) group, which received a stent in the pulmonary valve orifice, inducing PR. After 2-3 months, animals were subjected to cardiac magnetic resonance imaging. A subset of animals (n = 6) then underwent percutaneous pulmonary valve replacement (PPVR) with follow-up 1 month later. Longitudinal, lateral and septal contributions to stroke volume (SV) were quantified by measuring volumetric displacements from end-diastole to end-systole in the cardiac short axis and long axis. RESULTS: PR resulted in a lower longitudinal contribution to RV stroke volume, compared to controls (60.0 ± 2.6% vs. 73.6 ± 3.8%; P = 0.012). Furthermore, a compensatory increase in septal contribution to RVSV was observed (11.0 ± 1.6% vs. -3.1 ± 1.5%; P < 0.0001). The left ventricle (LV) showed counter-regulation with an increased longitudinal LVSV. Changes in RV longitudinal function were reversed by PPVR. CONCLUSION: These findings suggest that PR contributes to decreased RV longitudinal function in the absence of scarring from cardiac surgery. Measurement of longitudinal RVSV may aid risk stratification and timing for interventional correction of PR in TOF patients.

Melody transcatheter valve: Histopathology and clinical implications of nine explanted devices.

OBJECTIVES: We examined interventionally implanted valved Melody conduits after surgical explantation by means of histology and immunohistochemistry and matched these findings with clinical data in order to assess in vivo biocompatibility and to identify risk factors for graft failure. METHODS: 9 Melody valves had been implanted in 8 patients (pulmonary n = 7, tricuspid position n = 1). Indication for explantation included significant obstruction in 7 patients and valve insufficiency in 1 patient. 4 of 8 patients had suffered from endocarditis. Mean interval between implantation and explantation was 3.2 (1.8-5.2) years. All explants were worked up using a uniform protocol with fixation in formalin and embedding in methylmethacrylate. RESULTS: All but one valve of the explanted Melody grafts were thin and histologically intact without any pathological findings. Complete neo-endothelialization could be demonstrated by means of immunohistochemistry. All 4 Melody valves from patients with endocarditis showed dense granulocytic infiltrations, 3 of these showed thrombotic material within the valves. CONCLUSION: This report covers the first series of explanted Melody valves from humans applying a uniform protocol for histopathological examination. Good biocompatibility of the Melody valves could be demonstrated after a mid-term follow-up. Factors for graft failure included endocarditis, outgrowth, and residual stenosis. These findings may have significant implications for the implant procedure as well as care of the patients during long-term follow-up.

The Effects of Pulmonary Valve Replacement for Severe Pulmonary Regurgitation on Exercise Capacity and Cardiac Function.

Patients may develop hemodynamic abnormalities after right ventricular outflow tract (RVOT) repair. Re-intervention timing remains a dilemma. This study evaluates exercise capacity and RV function before and after intervention using age-related comparisons. Twenty-six patients with severe pulmonary regurgitation (PR) after initial repair scheduled for pulmonary valve replacement (PVR) were enrolled. Metabolic treadmill testing (EST) and MRI were obtained before and after surgery. EST results were compared with matched controls. Preoperative exercise time and peak oxygen consumption (VO2 max) were significantly diminished compared with controls but were not significantly different postoperatively. The patients were then split into age-related cohorts. When comparing pre-PVR and post-PVR exercise time and VO2 max among themselves, neither cohort showed significant differences. However, patients younger than 25 years had better postoperative results, an age-related difference not seen in the controls. Preoperative MRI showed significantly dilated RV, PR, and low normal function. After PVR, the right to left ventricular end-diastolic volume ratio (RVEDV:LVEDV) and pulmonary artery regurgitant fraction (RF) significantly decreased. There was no change in ventricular ejection fractions (EF). Severe PR, decreased RVEF, and RV dilation can significantly diminish exercise capacity. PVR improves RVEDV:LVEDV and RF, but not EF. Younger patients had better exercise capacity that was maintained postoperatively. This age-related difference was not seen in the controls, indicating that earlier intervention may preserve exercise capacity. Serial ESTs in patients with severe PR following RVOT repair may identify deteriorating exercise capacity as an early indicator for the need for PVR.

Right-sided valve disease.

In this review, we discuss right-sided heart valve disease, namely tricuspid regurgitation (TR), tricuspid stenosis, pulmonary regurgitation, pulmonary stenosis and right-sided endocarditis. These are frequently seen in conjunction with other diseases, making assessment of their significance more difficult, but it has become increasingly clear that moderate or severe right-sided heart valve disease, in particular TR, is associated with worse prognosis. There remain large gaps in our knowledge of medical and interventional treatment, but in this article we outline what is known about the causes, presentation and management of these commonly seen conditions.

CT and MRI of pulmonary valvular abnormalities.

Pulmonary valve disease constitutes a wide spectrum of conditions. Traditionally, echocardiography has been the technique of choice for the evaluation of pulmonary and other valvular disease. However, with advances in technology, computed tomography (CT) and magnetic resonance imaging (MRI) are playing increasingly important roles in the evaluation of these disorders. In this article, we review the normal appearance of the pulmonary valve and then illustrate various variants and pathological entities of the pulmonary valve.

The relationship between longitudinal, lateral, and septal contribution to stroke volume in patients with pulmonary regurgitation and healthy volunteers.

Septal systolic motion is towards the left ventricle (LV) in healthy hearts. Patients with pulmonary regurgitation (PR) and right ventricular (RV) volume overload have systolic septal motion toward the RV. This may affect the longitudinal contribution from atrioventricular plane displacement (AVPD) and septal and lateral contribution to stroke volume (SV). The study aimed to quantify these contributions to SV in patients with PR. Cardiac magnetic resonance imaging was used for assessment of cardiac volumes. Patients (n = 30; age 9-59 yr) with PR due to surgically corrected tetralogy of Fallot and 54 healthy controls (age 10-66 yr) were studied. Longitudinal contribution to RVSV was 47 ± 2% (means ± SE) in patients with PR and 79 ± 1% in controls (P < 0.001). Lateral contribution to RVSV and LVSV was 40 ± 1 and 62 ± 2% in patients and 31 ± 1 and 36 ± 1% in controls (P < 0.001 for both). Septal motion contributed to RVSV by 8 ± 1% in patients and by 7 ± 1% to LVSV in controls (P < 0.001). PR patients have decreased longitudinal contribution to RVSV and increased lateral pumping, resulting in larger outer volume changes and septal motion towards the RV. The changes in RV pumping physiology may be explained by RV remodeling resulting in lower systolic inflow of blood into the right atrium in relation to SV. This avoids the development of pendulum volume between the caval veins and right atrium, which would occur in PR patients if longitudinal contribution to SV was preserved. Decreased AVPD suggests that tricuspid annular excursion, a marker of RV function, is less valid in these patients.

Impact of transcatheter pulmonary valve replacement on biventricular strain and synchrony assessed by cardiac magnetic resonance feature tracking.

BACKGROUND: Transcatheter pulmonary valve (TPV) replacement is an emerging therapy intended to restore pulmonary valve function in patients with right ventricular outflow tract conduit dysfunction; the impact of this technique on ventricular strain and synchrony is not known. METHODS AND RESULTS: Cardiac magnetic resonance and ECG data acquired at 1 center as part of the US Melody TPV trial were analyzed. Biventricular strain and mechanical synchrony measurements were made based on short-axis and 4-chamber steady-state free precession images using feature tracking software. Post- versus pre-TPV replacement findings were compared for all patients (n=31) and subgroups with predominant pulmonary regurgitation (n=13) or stenosis (n=18). Most patients had tetralogy of Fallot (18/31). After TPV replacement, left ventricular (LV) circumferential strain increased for the whole cohort (P<0.001) and both subgroups (pulmonary regurgitation P=0.01; pulmonary stenosis P=0.02). LV longitudinal strain increased for the whole cohort (P=0.02) and pulmonary regurgitation subgroup (P=0.05); circumferential right ventricular strain increased for the pulmonary stenosis group only (P=0.05). LV longitudinal synchrony improved significantly in the pulmonary regurgitation group (maximum wall delay P=0.03; cross-correlation delay P=0.01). Electric measures of synchrony did not improve. CONCLUSIONS: In patients with right ventricular outflow tract conduit dysfunction, TPV replacement is associated with improved global LV strain, as well as improved right ventricular strain and LV synchrony in subgroups. Given the associations between strain and synchrony and clinical outcomes, these findings support potential long-term benefits of TPV replacement.

[Minimally invasive pulmonary valve replacement in pediatric patients: importance of imaging]. / Minimal-invasiver Pulmonalklappenersatz bei pädiatrischen Patienten: Stellenwert der Bildgebung.

CLINICAL/METHODICAL ISSUE: Right ventricular outflow tract (RVOT) dysfunction with pulmonary regurgitation or obstruction is a common postsurgical consequence in congenital heart disease. STANDARD RADIOLOGICAL METHODS: Magnetic resonance imaging (MRI) is widely accepted as standard method of imaging in congenital heart disease. It provides anatomical and functional information without radiation exposure and is therefore well suited for serial examinations. METHODICAL INNOVATIONS: Percutaneous pulmonary valve implantation (PPVI) has been shown to be a safe and effective treatment option for patients with pulmonary valve insufficiency or stenosis. Correct patient selection for PPVI is crucial. It is important to be familiar with the indications and anatomical requirements for stent placement and to tailor imaging protocols. PERFORMANCE: Imaging the RVOT, assessment of right ventricular volumes and function and calculation of pulmonary flow and regurgitation are core elements of the MRI examination prior to PPVI. Low interobserver and intraobserver variation allows even small changes to be detected. ACHIEVEMENTS: Imaging provides relevant information for correct patient selection for PPVI and is part of postinterventional follow-up. Imaging is an important tool for documentation of success and for detection of complications. PRACTICAL RECOMMENDATIONS: Several imaging modalities are used for evaluation of RVOTs; however, MRI can provide answers to most questions without radiation exposure.

Doppler-derived strain and strain rate imaging assessment of right ventricular systolic function in adults late after tetralogy of Fallot repair: an observational study.

OBJECTIVE: Tetralogy of Fallot (TOF) is the most common form of cyanotic congenital heart disease. Today, we are faced with an increasing number of patients with residual pulmonary regurgitation (PR) late after TOF repair. The right ventricular (RV) volumes and function are among the most important factors influencing clinical decision-making. Cardiac magnetic resonance (CMR) is the gold standard method for the quantitative assessment of the RV function; it is, however, expensive for routine clinical follow-up and sometimes is contraindicated. We sought to evaluate the RV systolic function via CMR and compare it with Doppler-derived strain(S) and strain rate (SR) imaging in patients with repaired TOF. METHODS: In an observational cross-sectional study, 70 patients (22 women, mean age=22±4.9 years) late after TOF repair with severe PR were evaluated. Peak systolic strain and SR in the basal, mid, and apical segments of RV free wall (RVFW) were measured and compared with the RV function measured in the short-axis cine MR. Associations between RVEF and S/SR, investigated by ordinal logistic regression models. RESULTS: Significant association was observed between RV function and mean S of all the three segments of the RVFW segments [OR (CI95%): 1.17 (1.05-1.31)]. Association between RV function and mean SR of all the three segments of the RVFW segments was borderline significant [OR (CI95%): 1.7 (0.97-2.93)]. CONCLUSION: There was a significant correlation between the Doppler-derived mean strain of RVFW and the RV function measured by CMR in adults late after TOF repair. These quantitative methods improved the assessment of the RV function and served as an additional method to follow up patients with contraindications to CMR.

An ovine model of pulmonary insufficiency and right ventricular outflow tract dilatation.

BACKGROUND AND AIM OF THE STUDY: The treatment of pulmonary insufficiency (PI) following reconstructive surgery of the right ventricular outflow tract (RVOT) in repair of the tetralogy of Fallot remains a significant challenge. The study aim was to establish an ovine model of dilated RVOT and PI, and to quantify the degree of PI and right ventricular remodeling over an eight-week period, using magnetic resonance imaging (MRI). METHODS: Five sheep underwent baseline MRI scanning and catheterization. The weight-indexed right and left ventricular end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF) and pulmonary regurgitant fraction (RF) were measured at baseline. The animals then underwent pulmonary valvectomy and transannular patch repair of the RVOT. Repeat MRI and hemodynamic measurements were obtained after an eight-week period. RESULTS: The indexed RVEDV increased from 49 +/- 4.0 ml/m2 at baseline to 80 +/- 10.3 ml/m2 at eight weeks after valvectomy (p = 0.01), while the indexed RVESV increased from 13 +/- 3.4 ml/m2 to 33 +/- 8.8 ml/m2 (p = 0.01). The indexed RVSV increased from 36 +/- 3.7 ml/m2 to 47 +/- 1.7 ml/m2 (p = 0.01). The RVEF at baseline was 74 +/- 6%, and this decreased to 59 +/- 5% at follow up (p = 0.02). The RF at baseline was 0 +/- 0% and was increased to 37 +/- 3% at eight weeks after valvectomy (p < 0.001). The left ventricular (LV) function was also diminished: LVEF at baseline was 67 +/- 2%, versus 49 +/- 10% at follow up (p = 0.01). Both, the RV and LV end-diastolic pressures were significantly elevated at follow up. CONCLUSION: All five animals developed pulmonary regurgitation sufficient to cause significant RV dilatation and diminished RV and LV functions. This model may be used to investigate novel therapeutic approaches in the treatment of this difficult clinical problem.

Virtual and real bench testing of a new percutaneous valve device: a case study.

AIMS: To validate patient-specific computational testing of a second-generation device for percutaneous pulmonary valve implantation (PPVI), against realistic in vitro data. METHODS AND RESULTS: Tests were initially carried out in a simple loading mode, performing a compliance test on a rapid prototyped cylinder. This model was reproduced computationally and validated against the experimental data. A second-generation PPVI stent-graft, with no valve mounted, was then deployed in a simplified cylindrical geometry, measuring its displacement when subjected to a pressure pulse. Experimental and computational measurements were in good agreement. Finally, having selected a patient regarded as unsuitable for first-generation PPVI, but potentially suitable for a second-generation device, the stent-graft was studied in the rapidly prototyped patient-specific right ventricular outflow tract (RVOT). Stent positioning and radial displacements with pulsatile flow were observed in a mock circuit using fluoroscopy imaging. Stent deformation and anchoring were measured both in vitro and computationally. Both tests indicated that the stent was well anchored in the RVOT, especially in the distal position, and its central region was rounded, ensuring, were a valve present, optimal valve function. CONCLUSION: We suggest that an experimentally validated computational model can be used for preclinical device characterisation and patient selection.

Valve-sparing options in tetralogy of Fallot surgery.

Given late outcomes of patients with tetralogy of Fallot repaired in the 1970s and 1980s, as well as a better understanding of the late deleterious effects of pulmonary regurgitation, there is a tendency toward preservation of the pulmonary valve function during primary repair of tetralogy of Fallot. The bar keeps moving downward, to include smaller and more dysmorphic pulmonary valves. This article reviews some useful indications and techniques for valve-sparing options, including intraoperative balloon dilation and cusp reconstruction using a patch. Just like other valve repair techniques, no one technique can be applied uniformly, and surgeons must master a wide armamentarium of techniques.

Tissue-velocity magnetic resonance imaging and tissue Doppler imaging to assess regional myocardial diastolic velocities at the right ventricle in corrected pediatric Tetralogy of Fallot patients.

OBJECTIVES: In patients with corrected Tetralogy of Fallot (cToF), pulmonary regurgitation and subsequent increased right ventricular (RV) end-diastolic volume are diastolic parameters related to adverse outcome. In addition, abnormalities of the RV outflow tract (RVOT) independently promote RV dilatation in cToF patients. Tissue Doppler imaging (TDI) and tissue-velocity magnetic resonance imaging (TV-MRI) enable quantitative assessment of regional diastolic performance by measuring myocardial velocities. Assessment of regional diastolic velocities of the RV may provide insight into the relation between RVOT dysfunction and RV dilatation in cToF patients. The aim of the study was to perform a direct comparison of TV-MRI against TDI to assess regional RV diastolic velocities in cToF patients and control subjects. In addition, the relationship between regional RV diastolic velocities and RV dilatation was investigated. MATERIALS AND METHODS: Thirty-four cToF patients (8-18 years) and 19 controls were studied. Early (E') and late (A') peak diastolic velocities and E'/A' ratio were assessed with TDI and TV-MRI at the RV free wall and at the RVOT. RV volumes and pulmonary regurgitation were quantified with planimetric and 3-dimensional flow MRI, respectively. RESULTS: Good correlation and agreement were observed between TDI and TV-MRI at both regions of the RV (RV free wall: E': r = 0.92, mean bias: 0.5 cm/s, A': r = 0.92, mean bias: 0.4 cm/s; RVOT: E': r = 0.92, mean bias: -0.3 cm/s, A': r = 0.95, mean bias: 0.03 cm/s). With both imaging techniques, regional RV diastolic velocities were significantly reduced in cToF patients. The E'/A' ratio at the RVOT (assessed with both TDI and TV-MRI) was related to RV end-diastolic volume, even after correction for pulmonary regurgitation (TDI: P < 0.01, TV-MRI: P = 0.05). CONCLUSIONS: TDI and TV-MRI can be used interchangeably for the assessment of regional diastolic velocities and performance of the RV in cToF patients and in healthy controls. Regional diastolic velocities at the RVOT are reduced in cToF patients as compared with controls. In addition to pulmonary regurgitation, impaired diastolic performance at the RVOT is independently related to RV dilatation.

Myocardial hypertrophy after pulmonary regurgitation and valve implantation in pigs.

BACKGROUND: Patients may suffer from right ventricular (RV) failure and malignant cardiac arrhythmias after late pulmonary valve replacement correcting pulmonary regurgitation (PR). But the underlying mechanisms of the refractory arrhythmias are not well understood. METHODS: The aim of present study was to characterize the RV myocardium after percutaneous pulmonary valve implantation (PPVI) in a porcine model after severe PR for 3months. RV histology was evaluated with morphometric methods and RV function was assessed with electrophysiology, echocardiography, and biochemical measures: The results were compared with age-matched sham-operated animals. RESULTS: At euthanasia, RV weight was increased compared to sham-animals, median 127 g (115-137) vs. 71 g (69.5-76.5), p=0.0007. RV myocyte diameters corrected for individual variation with the RV/LV ratio were enlarged, 1.06 (1.02-1.13) vs. 0.84 (0.80-0.91), p=0.0006. There were no excess collagen tissue (RV/LV ratio), p=0.77. Electrophysiological stimulation resulted in RV arrhythmia in 67% of the animals compared to 25% in the sham-operated animals, but this difference was not statistically significant, p=0.28. Echocardiography revealed geometrical dilation in end-systolic RV area, mean ± SD, 11.8 ± 4.9 cm(2) vs. 6.0 ± 3.5 cm(2), p=0.05, and end-diastolic area, 23.3 ± 10.4 cm(2) vs. 12.7 ± 2.5 cm(2), p=0.08. RV anterior free wall thickness was not increased, 0.7 ± 0.2 cm vs. 0.7 ± 0.1 cm, p=0.66. Echocardiographic functional parameters and plasma natriuretic peptides were unchanged. CONCLUSIONS: The RV does not completely recover after three months of PR with persistent myocardial hypertrophy one month after PPVI. Future studies should address whether RV chamber and cellular hypertrophy, without fibrosis or interventional scar tissue, may be substrate for arrhythmia.