Mitral valvuloplasty: when the art of repair meets the biological science.

The majority of approaches currently described and practiced in mitral repair surgery result in the vertical immobilization of the posterior leaflet, with the anterior leaflet striving to produce an adequate coaptation. Despite the satisfactory hemodynamic outcome and disappearance of mitral regurgitation, this non-physiological situation results in a redistribution of forces within the mitral apparatus with an increased stress on the leaflets. Biological evidences are pointing at the ability of the valvular interstitial cells to actively respond to biomechanical changes, switching their phenotype and producing different patterns of extracellular matrix proteins. This biological event translates to changes in the anatomical and mechanical properties of the leaflets, leading to an increased stiffening and a susceptibility to develop calcification. These concepts find a clinical reflex in reports on the long-term thickening and calcification of the leaflets after mitral repair, and in the leaflets remodeling phenomena described in chronically dilated ventricles. The importance of respecting the physiological movement and dynamics of the leaflets when performing a valvuloplasty is underlined, and a potential pharmacological modulation of the aforementioned biological processes to ameliorate long-term results of the repair is hypothesized.

Pulmonary homograft endocarditis and aortic autograft failure after Ross procedure: a double stentless bioprosthesis approach.

The case is reported of a 38-year-old male patient with pulmonary homograft acute infective endocarditis and aortic root dilation that occurred 13 years after a Ross procedure for bicuspid aortic valve regurgitation. Aortic and pulmonary root replacements were performed, using a Freestyle stentless aortic root bioprosthesis in both cases, with excellent hemodynamics on postoperative echocardiography. In addition, preoperative systemic septic embolization had occurred despite an absence of left-sided endocarditis, presumably due to an intrapulmonary shunt. This case report demonstrates the feasibility of a double stentless bioprosthesis approach, and stresses the need to remain vigilant for septic embolization even in isolated right-sided endocarditis.

Haemodynamics and left ventricular function in heart failure patients: comparison of awake versus intra-operative conditions.

BACKGROUND: Heart failure patients are increasingly subjected to surgery. Left ventricular (LV) function is generally assessed in awake patients, but intra-operative LV function is not well studied. AIM: To investigate the relation between LV function indices obtained in the catheterization laboratory and those obtained intra-operatively. METHODS: We enrolled 11 patients with heart failure (NYHA III-IV) scheduled for surgical interventions. LV function was assessed by pressure-volume loops (conductance catheter) during diagnostic catheterizations and intra-operatively under anaesthetized conditions. RESULTS: Compared to awake conditions, cardiac output was unchanged intra-operatively but ejection fraction was significantly reduced (-16%) due to increased end-diastolic volume (+13%). Systolic and diastolic LV pressure and afterload (E(A)) dropped significantly (-32%, -22%, -35%, respectively). LV systolic function assessed by dP/dt(MAX) and the end-systolic pressure-volume relation (E(ES)) was significantly reduced (-34%, -35%). LV diastolic stiffness was reduced (-44%). Ventricular-arterial coupling (E(A)/E(ES)) was maintained. CONCLUSION: Intra-operative cardiac output was unchanged compared to awake conditions due to a balance between reduced systolic and improved diastolic function. Ventricular-arterial coupling was maintained by a reduced afterload. Presumably, systolic function and afterload were reduced by anaesthesia, whereas diastolic function improved after pericardectomy. These findings provide insight into the combined effects of anaesthesia, thoracotomy and pericardectomy, and help to interpret LV function measurements in intra-operative conditions.

Clinical efficacy of surgical heart failure therapy by ventricular restoration and restrictive mitral annuloplasty.

BACKGROUND: Treatment of heart failure by advanced surgical procedures such as ventricular restoration (SVR) and restrictive mitral annuloplasty (RMA) is increasingly applied. We studied clinical efficacy of heart failure surgery in patients with severe heart failure. METHODS AND RESULTS: Thirty-three patients (New York Heart Association (NYHA) class III/IV, left ventricular ejection fraction < or =35%) were included. Patients with moderate to severe mitral regurgitation underwent RMA (85%) and patients with anteroseptal aneurysm underwent SVR (52%). A combined procedure was performed in 12 patients, and additional coronary artery bypass grafting in 27 patients. Clinical and echocardiographic parameters were assessed at baseline and 6 months after surgery. Operative mortality was 3% (n = 1), in-hospital mortality was 9% (n = 3), and there was no late mortality. All clinical parameters were significantly improved at 6 months' follow-up (P < .001); NYHA class improved from 3.4 +/- 0.5 to 1.5 +/- 0.5, Quality-of-life score improved from 44 +/- 22 to 16 +/- 12, and 6-minute walking distance increased from 248 +/- 134 m to 422 +/- 113 m. Left ventricular end-diastolic volume decreased from 107 +/- 32 to 80 +/- 20 mL/m(2) (P < .001) and end-systolic volume decreased from 78 +/- 32 to 53 +/- 15 mL/m(2) (P < .001), whereas ejection fraction improved from 29 +/- 9 to 35 +/- 7% (P < .01). CONCLUSIONS: Surgical treatment of severe heart failure by SVR or RMA was associated with 12% mortality at 6 months. Surviving patients showed highly significant functional and clinical improvements.

Artificial chordae for pediatric mitral and tricuspid valve repair.

OBJECTIVE: To evaluate pediatric atrioventricular valve repair with artificial chordae. METHODS: Between February 2001 and January 2006, artificial chords were used in 21 children with severe mitral or tricuspid valve regurgitation. Patients with AVSD were excluded. Median age was 84 (1-194) months. Five patients had isolated tricuspid valve anomalies, 16 had mitral valve anomalies (associated tricuspid annular dilatation in 4). Tricuspid neochordae were placed to anterior (three patients) and septal (two patients) leaflets. Mitral neochordae were placed to anterior (15 patients) and posterior (1 patient) leaflets. Additional ring annuloplasties were performed in 12 (mitral 11, tricuspid 1), as well as 2 de Vega tricuspid annuloplasties. Patch insertion was used in acute endocarditis (tricuspid one). All echocardiographic studies were reviewed and analyzed by a single cardiologist. RESULTS: No mortality occurred. Follow-up was complete (mean 28+/-18 months). Two patients were reoperated, one for mitral ring dehiscence and one for recurring mitral valve insufficiency. Both valves were replaced by mechanical valve prosthesis. At last follow-up tricuspid insufficiency was mild (three) or moderate (two). Moderate insufficiency occurred due to remaining restriction of the septal leaflet after repair in endocarditis (one) and remaining prolapse of the anterior leaflet (one). Mitral insufficiency was absent (five), mild (seven), or moderate (two). Moderate insufficiency was caused by recurrent anterior leaflet shortening after valve repair in rheumatic valve disease (two). Valve restriction caused by artificial chordae was not found. CONCLUSIONS: Mitral and tricuspid valve repair with artificial chordae in children demonstrated acceptable results. Despite patient growth, valvular restriction by the artificial chordae was not observed ad mid-term follow-up.

Diaphragm plication in adult patients with diaphragm paralysis leads to long-term improvement of pulmonary function and level of dyspnea.

OBJECTIVE: There is still controversy about the feasibility and long-term outcome of surgical treatment of acquired diaphragm paralysis. We analyzed the long-term effects on pulmonary function and level of dyspnea after unilateral or bilateral diaphragm plication. METHODS: Between December 1996 and January 2006, 22 consecutive patients underwent diaphragm plication. Before surgery, spirometry in both seated and supine positions and a Baseline Dyspnea Index were assessed. The uncut diaphragm was plicated as tight as possible through a limited lateral thoracotomy. Patients with a follow-up exceeding 1 year (n=17) were invited for repeat spirometry and assessment of changes in dyspnea level using the Transition Dyspnea Index (TDI). RESULTS: Mean follow-up was 4.9 years (range 1.2-8.7). All spirometry variables showed significant improvement. Mean vital capacity (VC) in seated position improved from 70% (of predicted value) to 79% (p<00.03), and in supine position from 54% to 73% (p=0.03). Forced expiratory volume in 1s (FEV1) in supine position improved from 45% to 63% (p=0.02). Before surgery the mean decline in VC changing from seated to supine position was 32%. At follow-up this had improved to 9% (p=0.004). For FEV1 these values were 35% and 17%, respectively (p<0.02). TDI showed remarkable improvement of dyspnea (mean+5.69 points on a scale of -9 to +9). CONCLUSION: Diaphragm plication for single- or double-sided diaphragm paralysis provides excellent long-term results. Most patients were severely disabled before surgery but could return to a more or less normal way of life afterwards.

Effective Orifice Area during Exercise in Bileaflet Mechanical Valve Prostheses.

BACKGROUND: The aims of this study were to investigate the evolution of the transprosthetic pressure gradient and effective orifice area (EOA) during dynamic bicycle exercise in bileaflet mechanical heart valves and to explore the relationship with exercise capacity. METHODS: Patients with bileaflet aortic valve replacement (n = 23) and mitral valve replacement (MVR; n = 16) prospectively underwent symptom-limited supine bicycle exercise testing with Doppler echocardiography and respiratory gas analysis. Transprosthetic flow rate, peak and mean transprosthetic gradient, EOA, and systolic pulmonary artery pressure were assessed at different stages of exercise. RESULTS: EOA at rest, midexercise, and peak exercise was 1.66 ± 0.23, 1.56 ± 0.30, and 1.61 ± 0.28 cm2, respectively (P = .004), in aortic valve replacement patients and 1.40 ± 0.21, 1.46 ± 0.27, and 1.48 ± 0.25 cm2, respectively (P = .160), in MVR patients. During exercise, the mean transprosthetic gradient and the square of transprosthetic flow rate were strongly correlated (r = 0.65 [P < .001] and r = 0.84 [P < .001] for aortic valve replacement and MVR, respectively), conforming to fundamental hydraulic principles for fixed orifices. Indexed EOA at rest was correlated with exercise capacity in MVR patients only (Spearman ρ = 0.68, P = .004). In the latter group, systolic pulmonary artery pressures during exercise were strongly correlated with the peak transmitral gradient (ρ = 0.72, P < .001). CONCLUSIONS: In bileaflet mechanical valve prostheses, there is no clinically relevant increase in EOA during dynamic exercise. Transprosthetic gradients during exercise closely adhere to the fundamental pressure-flow relationship. Indexed EOA at rest is a strong predictor of exercise capacity in MVR patients. This should be taken into account in therapeutic decision making and prosthesis selection in young and dynamic patients.

MRI to evaluate left atrial and ventricular reverse remodeling after restrictive mitral annuloplasty in dilated cardiomyopathy.

BACKGROUND: Data on reverse remodeling of the left atrium (LA) and left ventricle (LV) after restrictive annuloplasty in patients with dilated cardiomyopathy are scarce, and follow-up studies are performed with echocardiography. METHODS AND RESULTS: Twenty patients with dilated cardiomyopathy and severe mitral regurgitation selected for restrictive mitral annuloplasty underwent serial MRI studies (within 1 week before surgery, and 2 months [n =18] and 1 year [n =13] after surgery). Early mortality was 10%; all patients were free from endocarditis and thromboembolism. New York Heart Association class improved from 3.2+/-0.4 to 1.2+/-0.9. Only 1 patient developed recurrent severe mitral regurgitation during follow-up and it was re-repaired. LA end-systolic volumes decreased significantly over time (from 165+/-48 mL to 109+/-23 mL to 111+/-28 mL; P < 0.01), as did LA end-diastolic volumes (from 92+/-32 mL to 71+/-22 mL to 75+/-17 mL; P = 0.01). LV end-diastolic volumes decreased significantly (from 244+/-56 mL to 184+/-54 mL to 195+/-67 mL; P < 0.01), whereas end-systolic volumes did not change significantly. LV ejection fraction increased significantly (from 35+/-8% to 46+/-13% to 46+/-15%; P < 0.01) and LV mass decreased significantly (from 150+/-43 grams to 132+/-39 grams to 136+/-33 grams; P = 0.02). CONCLUSIONS: Restrictive annuloplasty in patients with dilated cardiomyopathy yielded excellent clinical results associated with significant LA and LV reverse remodeling over time as demonstrated by MRI.

Histology of vascular myocardial wall of left atrial body after pulmonary venous incorporation.

During embryonic development, the common pulmonary vein (PV) becomes incorporated into the left atrium, giving rise to separate PV ostia. We describe the consequences of this incorporation process for the histology of the left atrium and the possible clinical implications. The histology of the left atrial (LA) wall in relation to PV incorporation was studied immunohistochemically in 16 human embryos and fetuses, 1 neonate, and 5 adults. The PV wall, surrounded by extrapericardially differentiated myocardial cells, was incorporated into the LA body. After incorporation, the composition of PVs and the smooth-walled LA body wall was histologically identical. The LA appendage, however, consisted of endocardial and myocardial layers without a vessel wall component. In 2 adults, the myocardium in the LA posterior wall was absent. At the transition of the LA body and LA appendage, a smooth-walled myocardial zone lacking the venous wall was observed. This zone was histologically identical to the sinus venarum of the right atrium. In conclusion, the LA body arises by incorporation and growth of PVs, presenting with a histologically identical structure of vessel wall covered by extrapericardially differentiated myocardium of PVs. Discontinuity of myocardium may be the substrate for arrhythmias, and absence of myocardium in some patients makes this area potentially vulnerable to damage inflicted by ablation strategies. A border zone between the LA body and LA appendage is hypothesized to be the left part of the embryonic sinus venosus.

Outcome after mitral valve repair for acute and healed infective endocarditis.

OBJECTIVE: To evaluate the long-term clinical and echocardiographic outcomes after mitral valve surgery for acute and healed infective endocarditis. METHODS: Of 37 consecutive patients presenting with native mitral valve endocarditis, mitral valve repair (MVRep) was feasible in 34 (92%) patients. In 17 (50%) patients, surgery was indicated during antibiotic therapy (acute endocarditis), whereas 17 (50%) underwent surgery after antibiotic therapy was completed (healed endocarditis). Patients were evaluated for early and long-term clinical and echocardiographic outcome. RESULTS: In-hospital death occurred in two (6%) patients and two (6%) died during follow-up, with a 2-year survival of 100% in healed endocarditis as compared to 76% (p=0.03) in patients undergoing surgery in acute endocarditis. No patient with acute endocarditis needed repeat mitral valve surgery. Three (9%) patients underwent re-operation because of early mitral regurgitation (n=1) or late recurrent endocarditis (n=2). The average grade of mitral regurgitation was 3.8+/-0.4 (all grades 3 to 4+) before surgery and 0.6+/-0.8 during follow-up (p<0.001). Significant reductions in left atrial (from 52+/-8mm to 46+/-8mm, p=0.004), left ventricular end-diastolic (from 61+/-8mm to 54+/-8mm, p=0.001), and end-systolic dimensions (from 41+/-8mm to 36+/-9 mm, p=0.02) were observed during follow-up, compared to preoperative dimensions. Of note, significant reverse remodeling was only observed in patients undergoing surgery in healed endocarditis. CONCLUSION: MVRep for mitral valve endocarditis is feasible with good clinical results, maintained valve competency with significant reductions in left atrial and left ventricular dimensions after surgery.

Modeling ventricular function during cardiac assist: does time-varying elastance work?

The time-varying elastance theory of Suga et al. is widely used to simulate left ventricular function in mathematical models and in contemporary in vitro models. We investigated the validity of this theory in the presence of a left ventricular assist device. Left ventricular pressure and volume data are presented that demonstrate the heart-device interaction for a positive-displacement pump (Novacor) and a rotary blood pump (Medos). The Novacor was implanted in a calf and used in fixed-rate mode (85 BPM), whereas the Medos was used at several flow levels (0-3 l/min) in seven healthy sheep. The Novacor data display high beat-to-beat variations in the amplitude of the elastance curve, and the normalized curves deviate strongly from the typical bovine curve. The Medos data show how the maximum elastance depends on the pump flow level. We conclude that the original time-varying elastance theory insufficiently models the complex hemodynamic behavior of a left ventricle that is mechanically assisted, and that there is need for an updated ventricular model to simulate the heart-device interaction.

Mid-term results of leaflet augmentation in severe tricuspid functional tethering.

OBJECTIVES: Functional tricuspid regurgitation (FTR) is usually managed surgically using various types of annuloplasty. FTR has been reported to recur in up to 45% of patients, with severe leaflet tethering being an important risk factor for recurrence. The aim of this study is to report the clinical and echocardiographic mid-term results after leaflet augmentation in patients with FTR due to severe leaflet tethering. METHODS: From May 2008 to July 2014, 22 patients were found to have a severe FTR with a tethering height of at least 8 mm; all of them underwent leaflet augmentation: the anterior and part of the posterior leaflet were detached from the anterior annulus; a patch of fresh autologous pericardium was used to generously fill the gap between the anterior annulus and the detached leaflet. A 5/0 Pronova suture locked at every step was used to avoid any purse string effect. In 2 patients, the septal leaflet also needed to be augmented using a comparable technique. In all but one (annular calcification) patient, a semi-rigid ring annuloplasty was added. The mean age was 67.1 ± 13.7 years; it was a redo procedure in 12 cases (54.5%), 11 patients (50%) had right ventricle failure and 3 (23.1%) had renal failure. RESULTS: The median follow-up was 2.1 ± 1.9 years. Thirty-day and 4-year survival averaged at 81.1 ± 8.5 and 71.6 ± 9.8%, respectively. At 4 years, 84 ± 10.6% of the survivors were in NYHA class I or II and only 2 patients had a TR of ≥2 with a global freedom from TR ≥2 of 85.7 ± 13.2%. There was no reintervention. CONCLUSIONS: Tricuspid leaflet augmentation combined with annuloplasty is feasible and leads to excellent clinical and echocardiographical mid-term results even in the presence of severe leaflet tethering and right ventricular failure.

Restrictive annuloplasty and coronary revascularization in ischemic mitral regurgitation results in reverse left ventricular remodeling.

BACKGROUND: Data on combined coronary artery bypass grafting (CABG) and restrictive annuloplasty in patients with ischemic cardiomyopathy are scarce, and the effect on reverse left ventricular (LV) remodeling is unknown. METHODS AND RESULTS: 51 patients with ischemic LV dysfunction (LV ejection fraction 31+/-8%) and severe mitral regurgitation (grade 3 to 4+) underwent CABG and restrictive annuloplasty with stringent downsizing of the mitral annulus (by 2 sizes, Physio-ring, mean size 28+/-2). Serial transthoracic echocardiographic studies were performed (before surgery and within 3 months and 1.5 years after surgery) to assess mitral regurgitation, transmitral gradient, leaflet coaptation, and left atrial and LV reverse remodeling. Clinical follow-up (New York Heart Association [NYHA] class, survival, events) was assessed at 2-year follow-up. Early operative mortality was 5.6%; at 2-year follow-up, all patients were free of endocarditis and thromboembolism, and 1 needed re-operation for recurrent mitral regurgitation; 2-year survival was 84%. NYHA class improved from 3.4+/-0.8 to 1.3+/-0.4 (P<0.01), with all patients in class I/II. Intraoperative transesophageal echo showed minimal (grade 1+) mitral regurgitation in 8 patients and none in 43, without stenosis. Leaflet coaptation was 0.8+/-0.2 cm. These values remained unchanged; all patients had no or minimal (grade 1+) mitral regurgitation at 2-year follow-up. LV end-systolic and end-diastolic dimensions decreased from 51+/-10 to 43+/-12 mm (P<0.001) and from 64+/-8 to 58+/-11 mm (P<0.001). Left atrial dimension decreased from 53+/-8 to 47+/-7 mm (P<0.001). CONCLUSIONS: Excellent results of combined restrictive annuloplasty and CABG were obtained. Residual mitral regurgitation was absent/minimal at 2-year follow-up, associated with a significant reduction in left atrial dimension and LV reverse remodeling.

Acute hemodynamic effects of restrictive mitral annuloplasty in patients with end-stage heart failure: analysis by pressure-volume relations.

OBJECTIVE: Recent studies show beneficial long-term effects of restrictive mitral annuloplasty in patients with end-stage heart failure. However, concerns are raised about possible adverse effects on early postoperative systolic and diastolic function, which might limit application of this approach in patients with heart failure. Therefore we evaluated the acute effects of restrictive mitral annuloplasty on left ventricular function by using load-independent pressure-volume relations. METHODS: In 23 patients (heart failure, n = 10; control, n = 13) we determined left ventricular systolic and diastolic function before and after surgical intervention by means of pressure-volume analysis with a conductance catheter. All patients with heart failure underwent stringent restrictive mitral annuloplasty (2 sizes smaller than the measured size), and 4 received additional coronary artery bypass grafting. Transesophageal echocardiography was used for evaluation of valve repair. Patients with preserved left ventricular function who underwent isolated coronary artery bypass grafting served as control subjects. RESULTS: Restrictive mitral annuloplasty (ring size, 25 +/- 1) restored leaflet coaptation (8.0 +/- 0.2 mm) with normal pressure gradients (2.9 +/- 1.8 mm Hg). Restrictive mitral annuloplasty did not change cardiac output (5.0 +/- 1.8 to 5.3 +/- 0.9 L/min, P = .516), left ventricular ejection fraction (29% +/- 5% to 32% +/- 8%, P = .315), or end-systolic elastance (0.86 +/- 0.50 to 0.99 +/- 1.05 mm Hg/mL, P = .688). After restrictive mitral annuloplasty, end-diastolic volume tended to decrease (237 +/- 89 to 226 +/- 52 mL, P = .564), whereas end-diastolic pressure remained unchanged (14 +/- 6 to 15 +/- 5 mm Hg, P = .356). Diastolic chamber stiffness tended to increase (0.027 +/- 0.035 to 0.041 +/- 0.047 mL -1 , P = .542) but not significantly. Peak left ventricular wall stress was unchanged (356 +/- 91 to 346 +/- 85 mm Hg, P = .668). Baseline values in the control group were different, but changes in most parameters after surgical intervention showed similar nonsignificant trends. CONCLUSION: Mitral valve repair by means of restrictive mitral annuloplasty effectively restores mitral valve competence without inducing significant acute changes in left ventricular systolic or diastolic function in patients with end-stage heart failure.

Preoperative left ventricular dimensions predict reverse remodeling following restrictive mitral annuloplasty in ischemic mitral regurgitation.

OBJECTIVE: Ischemic mitral regurgitation can be treated with a restrictive mitral annuloplasty, with or without coronary revascularization. In this study, the extent of reverse remodeling of the left ventricle following this strategy is assessed, as well as the factors that influence it. METHODS: Eighty-seven consecutive patients with ischemic mitral regurgitation and a mean ejection fraction of 32+/-10% underwent restrictive mitral annuloplasty (downsizing by two ring sizes, median ring size 26), with additional coronary revascularization in 75 patients. All underwent transthoracic echocardiography 18 months after surgery to assess residual mitral regurgitation, mitral valve gradient and left ventricular end-systolic and end-diastolic dimensions. Univariate and multivariate analysis was performed to identify predictors for reverse remodeling, defined as a 10% reduction in left ventricular dimension. Receiver-operating characteristic analysis was used to identify cut-off values for preoperative left ventricular dimensions in predicting reverse remodeling. RESULTS: Early mortality was 8.0% (seven patients, three non-cardiac), late mortality was 7.5% (six patients, four non-cardiac). There were two reoperations (redo annuloplasty), and four readmissions for heart failure. At 29 months follow-up, NYHA class improved from 3.0+/-0.9 to 1.3+/-0.5 (P<0.01). Mitral regurgitation grade decreased from 3.1+/-0.5 to 0.6+/-0.6 at 18 months, left ventricular end-systolic dimension decreased from 52+/-8 to 44+/-11 mm (P<0.01), and end-diastolic dimension from 64+/-8 to 58+/-10mm (P<0.01). Multivariate analysis identified preoperative left ventricular end-diastolic dimension as the single best factor in predicting occurrence of reverse remodeling. For end-systolic dimension, 51mm was the optimal cut-off value to predict reverse remodeling (specificity and sensitivity 81%, area under curve 0.85); for end-diastolic dimension, the cut-off value was 65mm (specificity and sensitivity 89%, area under curve 0.92). CONCLUSIONS: Stringent restrictive mitral annuloplasty with or without revascularization provides excellent clinical results with acceptable mortality. At 18 months follow-up, there is no significant residual mitral regurgitation. Reverse remodeling occurs in the majority of patients, but is limited by preoperative left ventricular dimensions. In patients with a left ventricular end-diastolic dimension exceeding 65mm, additional surgical procedures are necessary to try and obtain reverse remodeling in this subgroup.

Results of the Ross operation in a pediatric population.

OBJECTIVE: To analyse the results of the mid-term clinical and echocardiographic follow-up of the pediatric Ross operation. METHODS: Echo-Doppler follow-up of 53 consecutive pediatric Ross procedures performed between 1994 and 2003. Median age was 9.7 years at time of operation (2 weeks-17.7 years). Six patients were younger than 3 months. Median age at follow-up was 15.6 years. Aortic valve/left ventricular outflow tract (LVOT) anomalies were congenital in 49 (92%). Seventy percent had previous surgery or balloon valvuloplasty. Root replacement was used in all. Thirteen patients (25%) had LVOT enlargement. Mean cross-clamp time was 113 (69-189) minutes. RESULTS: Early mortality occurred in 3 patients after emergency surgery following balloon failure (n=1) and extended Ross following interrupted arch/VSD repair (n=2). Late mortality was due to LV fibroelastosis in 2 patients and complicated pulmonary artery stenting in another. RVOT reoperations were required because of late homograft obstruction in 2 patients and because of pulmonary artery stenosis in another. Five patients (9.4%) were reoperated for pulmonary autograft dilatation (n=3) and for leaflet fibrosis or perforation (n=2). Autografts were repaired in two patients, while a mechanical valve was inserted in 3 cases. At 9 years the actuarial survival and event free survival were 89 and 74%, respectively. At last follow-up 90% of autograft diameters indexed to body surface area was above the 90th percentile of normal aortic root diameters. LVOT and RVOT gradients were low and autograft insufficiency was trivial to mild in 84% and mild to moderate in 16%. Autograft stenosis was not noticed. CONCLUSIONS: The pediatric Ross procedure remains an important tool but autograft dilatation also occurs in the pediatric population. The significance of this finding has yet to be determined.

Left ventricular function and chronotropic responses after normothermic cardiopulmonary bypass with intermittent antegrade warm blood cardioplegia in patients undergoing coronary artery bypass grafting.

OBJECTIVE: Recent studies indicate that normothermic cardiopulmonary bypass (CPB) with intermittent antegrade warm blood cardioplegia (IAWBC) may have metabolic and clinical advantages, but limited data exist on its effects on myocardial function. Therefore, we investigated the acute effects of this approach on systolic and diastolic left ventricular function and on chronotropic responses. METHODS: In 10 patients undergoing isolated CABG we obtained on-line left ventricular pressure-volume loops using the conductance catheter before and after normothermic CPB with IAWBC. Steady state and load-independent indices of left ventricular function derived from pressure-volume relations were obtained during right atrial pacing (80-100-120 beats/min) to determine baseline systolic and diastolic function and chronotropic responses. RESULTS: The mean time of CPB was 105+/-36 min (median 103, range 60-167 min) with a mean aortic cross-clamp time of 75+/-27 min (median 69, range 43-129 min). Baseline (80 beats/min) end-systolic elastance (E(ES)) did not change after CPB (1.22+/-0.53 to 1.12+/-0.28 mm Hg/ml, P>0.2), while the diastolic chamber stiffness constant (k(ED)) significantly increased (0.014+/-0.005 to 0.040+/-0.007 ml-1, P=0.018) and relaxation time constant (tau) significantly decreased (61+/-3 to 49+/-2 ms, P=0.004). Before CPB, incremental atrial pacing had no significant effects on E(ES) and tau but significant negative effects on kED (0.014+/-0.005 to 0.045+/-0.012 ml-1, P=0.013). After CPB, atrial pacing had significant positive effects on E(ES), tau and kED (E(ES): 1.12+/-0.28 to 2.60+/-1.54 mm Hg/ml, P=0.021; tau: 49+/-2 to 45+/-2 ms, P=0.009; kED: 0.040+/-0.007 to 0.026+/-0.005 mm Hg, P=0.010), indicating improved systolic and diastolic chronotropic responses. CONCLUSION: On-pump normothermic CABG with IAWBC preserved systolic function, increased diastolic stiffness, and improved systolic and diastolic chronotropic responses. Normalization of the chronotropic responses post-CPB is likely due to effects of successful revascularization and subsequent relief of ischemia.

Accurate quantitation of regurgitant volume with MRI in patients selected for mitral valve repair.

OBJECTIVE: Echocardiography, the currently preferred diagnostic approach for mitral valve regurgitation, cannot accurately quantify the amount of regurgitation. Flow quantification with MRI is possible, but the conventional method (1-directional velocity-encoding) acquires the flow at a fixed location during the cardiac cycle, which is not necessarily the location of the mitral valve during the whole cycle. In this study, the exact flow through the mitral valve was quantified with a 3-directional velocity-encoded MRI approach. METHODS: Ten patients with severe mitral valve regurgitation (class 3-4+with echocardiography) resulting from systolic restrictive motion of both leaflets (Carpentier IIIb) which were selected for valve repair and 10 healthy volunteers without cardiac valvular disease confirmed with echocardiography were included in this study. The intra-ventricular flow was sampled with a radial stack of six acquisition planes parallel to the long-axis of the left ventricle. Three-directional velocity-encoded MRI was performed resulting in the intra-ventricular flow velocity vector field for 30 phases during the cardiac cycle. The position of the mitral valvular plane in this vector field was indicated manually for each phase. Velocity values perpendicular to this plane determined the flow through the mitral valve. Both the 3-directional encoded mitral valve flow and the 1-directional encoded mitral valve flow were compared with the flow determined with MRI at the ascending aorta. RESULTS: One-directional velocity-encoded MRI showed a mean overestimation (P<0.01) of 25 ml/cycle compared to the aortic flow. Correlation was very poor (r(P)=0.15, P=0.68). The 3-directional velocity-encoded MRI on the other hand, showed no over/underestimation and a good correlation (r(P)=0.91, P<0.01 for volunteers, r(P)=0.90, P<0.01 for patients). The regurgitant flow fractions were between 3 and 30%. CONCLUSION: With 3-directional velocity-encoded MRI, measurement of the flow through the mitral valve is accurate and reproducible. This is a valuable tool for diagnosing and absolute quantification of regurgitant volume.

Is the air in Toronto, Rochester, and Cleveland different from that in London, Monaco, Leiden, Genk, Milan, and New York?

The tricuspid valve has been recently referred to as the "forgotten valve," because one now realizes that tricuspid regurgitation is bad for the patient and that reoperation for progressive tricuspid regurgitation after a left-sided valvular correction still carries a high mortality risk. However, the indication for concomitant tricuspid valve repair during a mitral valve repair procedure is still controversial, as illustrated by the reaction of Dr T. David to the presentation of Dr Chikwe and colleagues at the 2015 American Association for Thoracic Surgery meeting. One of the explanations for these divergent opinions could be that tricuspid regurgitation grading is largely unreliable because of the dependence of the right ventricle on the preload and of the discrepancy between clinical and hemodynamic data. Therefore, we need a parameter that does not depend on preload. An annular dilation of 40 mm or 21 mm/m(2) has been proposed and validated by many authors. The preoperative functional class also plays a major role. Tricuspid regurgitation is a progressive disease, but the presence of a concomitant mitral valve disease may aggravate annular dilation; therefore, the earlier we operate on the mitral valve, the less frequently patients will require concomitant tricuspid valve repair.