Francesca Viscardi

Comparative finite element model analysis of ascending aortic flow in bicuspid and tricuspid aortic valve.

In bicuspid aortic valve (BAV) disease, the role of genetic and hemodynamic factors influencing ascending aortic pathology is controversial. To test the effect of BAV geometry on ascending aortic flow, a finite element analysis was undertaken. A surface model of aortic root and ascending aorta was obtained from magnetic resonance images of patients with BAV and tricuspid aortic valve using segmentation facilities of the image processing code Vascular Modeling Toolkit (developed at the Mario Negri Institute). Analytical models of bicuspid (antero-posterior [AP], type 1 and latero-lateral, type 2 commissures) and tricuspid orifices were mathematically defined and turned into a volumetric mesh of linear tetrahedra for computational fluid dynamics simulations. Numerical simulations were performed with the finite element code LifeV. Flow velocity fields were assessed for four levels: aortic annulus, sinus of Valsalva, sinotubular junction, and ascending aorta. Comparison of finite element analysis of bicuspid and tricuspid aortic valve showed different blood flow velocity pattern. Flow in bicuspid configurations showed asymmetrical distribution of velocity field toward the convexity of mid-ascending aorta returning symmetrical in distal ascending aorta. On the contrary, tricuspid flow was symmetrical in each aortic segment. Comparing type 1 BAV with type 2 BAV, more pronounced recirculation zones were noticed in the latter. Finally, we found that in both BAV configurations, maximum wall shear stress is highly localized at the convex portion of the mid-ascending aorta level. Comparison between models showed asymmetrical and higher flow velocity in bicuspid models, in particular in the AP configuration. Asymmetry was more pronounced at the aortic level known to be more exposed to aneurysm formation in bicuspid patients. This supports the hypothesis that hemodynamic factors may contribute to ascending aortic pathology in this subset of patients.

Influence of Bicuspid Valve Geometry on Ascending Aortic Fluid Dynamics: A Parametric Study

Bicuspid aortic valve (BAV) predisposes to aortic aneurysms with a high prevalence. A first hypothesis for this phenomenon is related to fibrillin deficiency (genetic hypothesis). The present article focused on a complementary, hemodynamic hypothesis stating that it is the peculiar fluid dynamics of blood in the ascending aorta of patients with BAV configurations that leads to aneurysm formation. To corroborate this hypothesis, a parametric study was performed based on numerical simulations of ascending aorta hemodynamics with different configurations of orifice area and valve orientation. The resulting wall shear stress (WSS) distributions and degree of asymmetry of the blood jet were investigated, and surrogate indices introduced. The results showed that WSS was more pronounced in subjects with BAV morphologies, also in the nonstenotic case. In particular, a maximum WSS of 3Pa was found (vs. 1.5Pa in subjects with a tricuspid configuration). It is localized at the mid-ascending aorta, the segment more prone to dilate as shown by the index related to maximum WSS (0.869 in BAV vs. 0.322 in tricuspid). Moreover, the asymmetry of the blood flow was found larger for decreasing valve area, the related index at mid-ascending aorta being more than three times higher than that found for tricuspid configuration (0.70 vs. 0.20). Further, WSS and flow asymmetry were higher also at the sinus of Valsalva and sinotubolar junction for a latero-lateral (LL) BAV configuration in keeping with the clinical observation on association between BAV configurations and different aortic aneurysm morphology. These findings may help explain the higher risk of aneurysm formation in BAV patients. The proposed indices will require validation prior to application in clinical settings.

The Ross–Yacoub procedure for aneurysmal autograft roots: A strategy to preserve autologous pulmonary valves

OBJECTIVES Autograft dilatation is leading to an increase in root reoperations late after the Ross procedure. A 14-year clinical experience was reviewed to define the feasibility and outcome of the autograft valve-sparing root reoperation. METHODS One hundred twenty-six patients surviving an average of 7.4 +/- 9.9 years after the Ross procedure underwent cross-sectional clinical and echocardiographic examination. Study end points were freedom from autograft dilatation (diameter >4 cm or 2.1 cm/m(2)), root reoperation, root replacement, and functional outcome after the valve-sparing reoperation. RESULTS Thirty-one (25%) patients had dilatation, with 45% +/- 9% freedom at 14 years. In 14 (11%) patients an autograft aneurysm (>5.0 cm) was found: 12 had reoperations at 8.9 +/- 2.6 years after the Ross procedure. Risk factors for root reoperation at multivariate analysis were root technique (P = .01), root dilatation (P = .001), and follow-up duration (P = .06). Two patients had root replacement, and 10 (83%) had remodeling with valve preservation (8 Yacoub procedures and 2 sinotubular junction/ascending aorta procedures); all survived reoperation. Absence of severe autograft insufficiency (P = .04) and convergent-type aneurysm (P = .05) were associated with successful valve preservation. Fourteen-year freedom from root reoperation was 80% +/- 7%, and freedom from full root replacement was 97% +/- 4%. At 3.2 +/- 1.5 years (range, 0.2-4.8 years) after root reoperation, all patients are in New York Heart Association class I and are medication free: 9 of 10 patients have mild autograft valve insufficiency or less, and 1 required valve replacement 51 months after remodeling. One patient carried out 2 uncomplicated pregnancies 3 and 4 years after the Ross-Yacoub procedure. CONCLUSIONS Root reoperation with pulmonary valve preservation is feasible in the majority of patients with autograft aneurysms, allowing for maintenance of normal quality of life. Referral of patients with a dilated root before the appearance of severe valve insufficiency increases the likelihood of pulmonary valve sparing. Functional behavior of remodeled autograft roots is rewarding; however, continued observation is warranted.

Age at Repair Affects the Very Long-Term Outcome of Sinus Venosus Defect

BACKGROUND Records of patients who had repair of sinus venosus defect (SVD) between 1970 and 2008 were reviewed to predict very long-term outcome. METHODS Repairs occurred in 104 consecutive patients (51 men), aged 29 +/- 23 years (range, 1 to 70 years). Seven had isolated SVD and 97 had associated lesions that required concomitant operations. Five patients had preoperative arrhythmias; 24 (23%) were in New York Heart Association (NYHA) class III to V. Single-patch repair was done in 91 patients, caval translocation (Warden) in 7, and double-patch in 6. RESULTS Ten late deaths during 38 years of follow-up (mean, 15 +/- 20 years). Survival was 97% +/- 2% and 79% +/- 7% at 10 and 30 years. Thirty-one (29%) long-term survivors experienced 47 complications, including chronic/recurrent supraventricular tachycardia in 28, heart failure in 5, permanent pacing in 8, cerebrovascular accident in 3, and unrelated cardiac reoperation in 3. At 30 years, freedom from adverse cardiac events was 47% +/- 9%, from supraventricular tachycardia, 50% +/- 9%; from permanent pacing, 83 +/- 6%; and from cerebrovascular accident, 96% +/- 2%. Follow-up age was 42 +/- 23 years (range, 5 to 82 years); 74 patients (79%) were in NYHA class I, and 15 and 5 were in class II and III to IV, respectively. Baseline cardiac rhythm was sinus in 75 patients (84%), atrial fibrillation in 11 (12%), and paced in 8. Nine patients had moderate/severe pulmonary hypertension, and 8 had left ventricular dysfunction. Only older age at operation was associated with lower survival (p = 0.003), freedom from cardiac events (p = 0.001), supraventricular tachycardia (p = 0.009), and permanent pacing (p = 0.002). Repair before age 20 was associated with lower NYHA class at follow-up (p = 0.01). CONCLUSIONS SVD repair at an older age is associated with increased risk of late mortality, adverse cardiac events, and worse functional outcome. Repair during childhood is strongly advised.

Seven-Year Performance of the Edwards Prima Plus Stentless Valve with the Intact Non-Coronary Sinus Technique

Abstract  Objectives: Late results after stentless aortic valve replacement (AVR) may be jeopardized by progressive aortic dilatation. To define functional outcome using the intact non‐coronary sinus technique, all patients operated using the stentless Edwards Prima Plus xenograft were assessed. Methods: Between January 2000 and August 2007, 154 patients, aged 71 ± 9 years, underwent stentless AVR using a technique, which replaces the non‐coronary sinus and stabilizes two of three commissures. Indication was aortic valve stenosis (AS) in 103 (67%) patients: 33 (21%) had bicuspid valve and four endocarditis. Ninety‐six (62%) patients were in NYHA III‐IV, and 13 (8%) had LVEF <30%. Associated procedures were required in 59 (38%) patients (CABG, 34; ascending aorta, 22; others 3). Study endpoints were survival, freedom from valve‐related events, clinical status, and graft function. Results: There were two hospital and two late deaths during a 48 ± 19 months (1–92) follow‐up (97 ± 3% survival at seven years). Seven‐year freedom from structural failure, nonstructural failure, and endocarditis was 99 ± 1%, 97 ± 3%, and 98 ± 2%. Follow‐up NYHA (96 vs ten patients in class III‐IV, p = 0.001), and cardiac function (13 vs one patient with LVEF <30%, p = 0.02) were improved. Xenograft performance was satisfactory: 0–2 + aortic insufficiency (AI) in 147 (98%) patients, mean trans‐prosthetic pressure gradient 8 ± 4 (0–25 mmHg). Aortic root diameters were comparable to postoperative values (sinus of Valsalva, 36 ± 8 vs 35 ± 9 mm, p = ns; sinotubular junction, 32 ± 7 vs 34 ± 8 mm, p = ns). Conclusions: Stentless AVR with non‐coronary sinus replacement affords excellent late outcome and low rate of valve‐related events, even in complex patients (bicuspid valve, LV failure, and endocarditis). Aortic root dimensions remain stable over time allowing rewarding xenograft function.

Operative risk and outcome of surgery in adults with congenital valve disease.

To define risk and outcome of surgery in adults with congenital valve disease (CVD), experience between 2002 and 2005 with 371 CVD operations (288 males, aged 56 ± 9 years) was compared with 2102 for acquired valve disease (AVD) (69 ± 22 years, p = 0.02). Diagnosis included: bicuspid aortic valve (BAV), 337, s/p ToF repair, 11; atrio-ventricular valve dysfunction, 10; other, 13. Associated lesions were present in 259 patients (70% vs. 17%, p = 0.001): ascending aorta, 205; right ventricular outflow tract obstruction, 40; coronary artery, 34; mitral/tricuspid valve, 27; septal defect, 17; subaortic stenosis, 4; aortic arch, 4; other, 3. Fifty-two patients (14% vs. 2.5% AVD, p = 0.001) had undergone 75 prior operations (1.4/patient) and 14 (3.8% vs. 1.9% AVD, p = 0.04) required urgent/emergent surgery (endocarditis, dissection). Valve repair was done in 36 (10% vs. 3% AVD, p = 0.02) and replacement in 335: stentless solution (native, autograft, xenograft) was offered to 101 (29%) patients. In BAV, partial root replacement was associated in 63, complete in 77 and ascending aorta in 92. Three (0.8%) hospital deaths occurred (vs. 1.9% AVD, p = 0.2) due to endocarditis. Twenty-six patients (7.0% vs. 10.8% AVD, p = 0.003) experienced complications (cardiac, 7; neurologic, 6; respiratory, 5; renal, 3; sepsis/multiple organ failure (MOF), 2; hemorrhage, 8). Urgent/emergent surgery predicted hospital mortality (p = 0.001). During 5-year follow- up (average 2.6 ± 1.8 years), there was one late cardiac death and three reoperations (98% free). Despite higher prevalence of associated procedures, reoperation and emergent indication, operative risk in CVD is lower than in AVD, possibly because of younger age. Stentless valve surgery, allowing normal life-style (e.g., exercise, pregnancy), is increasingly preferred.

Aortic root physiology late after a "perfect" ross operation: magnetic resonance imaging study of three operative techniques.

In order to define physiological properties of the autograft root, magnetic resonance imaging (MRI) findings relative to three different operative techniques were compared with those of control subjects. Twenty-three patients, 18/5 M/F, aged 32 ± 9 years, underwent MRI assessment of the aortic root. Patients with normally functioning autograft valve and at least 4 years of follow-up (average 5.6 ± 1.9, range 4-10 years) were selected for each technique: six subcoronary (Group 1), nine inclusion (Group 2), and eight freestanding root (Group 3). Results were compared among patient groups and with seven control subjects, 6/1 M/F, aged 30 ± 2 years (P = ns). Morphological and functional properties were defined using transverse and paracoronal views, during systole and diastole. Mean aortic size in each group was greater than control, except for the LV-aortic junction and the sinus of Valsalva in Group 1 (26 ± 5 vs. 23 ± 3 mm, P = 0.2 and 33 ± 6 vs. 30 ± 5 mm, P = 0.3). Aortic valve plane rotation (P = 0.02) and root dilatation (P = 0.02) were more common in Group 3. Altered valve opening dynamics and asymmetrical aortic flow profile were also more common in Group 2 (P = 0.03) and Group 3 (P = 0.04). Distensibility was significantly reduced at sinus level in Group 2 and 3 compared with control (4.1 ± 3.5% and 3.6 ± 4.4% vs. 9.0 ± 4.7%, P = 0.03). Asymmetrical aortic flow profile was more common in patients with aortic dilatation (P = 0.05) and with severely reduced (<4%) root elasticity (P = 0.06). Among the three techniques, only subcoronary grafting allows preservation of physiological autograft valve dynamics, aortic flow and distensibility, at all root levels, late after operation. These findings may have relevant implications in the selection of the ideal Ross technique.

Familial fetal-type rhabdomyoma of the tricuspid valve in the neonate: Malignant course for a benign disease

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