Aortic root replacement with the freestyle stentless porcine aortic root bioprosthesis

Biological aortic valve replacement: advantages and optimal indications of stentless compared to stented valve substitutes. A review

Controversy still surrounds the optimal biological valve substitute for aortic valve replacement. In light of the current literature, we review advantages and optimal indications of stentless compared to stented aortic bio-prostheses. Recent meta-analyses, prospective randomized controlled trials and retrospective studies comparing the most frequently used stentless and stented aortic bio-prostheses were analyzed. In the present review, the types and implantation techniques of the bio-prosthesis that are seldom taken into account by most studies and reviews were integrated in the interpretation of the relevant reports. For stentless aortic root bio-prostheses, full-root vs. sub-coronary implantation offered better early transvalvular gradients, effective orifice area and left ventricular mass regression as well as late freedom from structural valve deterioration in retrospective studies. Early mortality and morbidity did not differ between the stentless and stented aortic bio-prostheses. Early transvalvular gradients, effective orifice area and regression of left ventricular hypertrophy were significantly better for stentless, especially as full-root, compared to stented bio-prostheses. The long-term valve-related survival for stentless aortic root and Toronto SPV bio-prosthesis was as good as that for stented pericardial aortic bio-prostheses. For full-root configuration this survival advantage was statistically significant. There seems to be not one but different ideal biological valve substitutes for different subgroups of patients. In patients with small aortic root or exposed to prosthesis-patient mismatch full-root implantation of stentless bio-prostheses may better meet functional needs of individual patients. Longer follow-ups on newer generation of stented bio-prostheses are needed for comparison of their hemodynamic performance with stentless counterparts especially in full-root configuration.

Full-root Aortic Valve Replacement by Stentless Aortic Xenografts in Patients with Small Aortic Roots

In patients with small aortic roots who need an aortic valve replacement with biological valve substitutes, the implantation of the stented pericardial valve might not meet the functional needs. The implantation of a too-small stented pericardial valve, leading to an effective orifice area indexed to a body surface area less than 0.85 cm²/m², is regarded as prosthesis-patient mismatch (PPM). A PPM negatively affects the regression of left ventricular hypertrophy and thus the normalization of left ventricular function and the alleviation of symptoms. Persistent left ventricular hypertrophy is associated with an increased risk of arrhythmias and sudden cardiac death. In the case of predictable PPM, there are three options: 1) accept the PPM resulting from the implantation of a stented pericardial valve when comorbidities of the patient forbid the more technically demanding operative technique of implanting a larger prosthesis, 2) enlarge the aortic root to accommodate a larger stented valve substitute, or 3) implant a stentless biological valve or a homograft. Compared to classical aortic valve replacement with stented pericardial valves, the full-root implantation of stentless aortic xenografts offers the possibility of implanting a 3-4 mm larger valve in a given patient, thus allowing significant reduction in transvalvular gradients. However, a number of cardiac surgeons are reluctant to transform a classical aortic valve replacement with stented pericardial valves into the more technically challenging full-root implantation of stentless aortic xenografts. Given the potential hemodynamic advantages of stentless aortic xenografts, we have adopted full-root implantation to avoid PPM in patients with small aortic roots necessitating an aortic valve replacement. Here, we describe in detail a technique for the full-root implantation of stentless aortic xenografts, with emphasis on the management of the proximal suture line and coronary anastomoses. Limitations of this technique and alternative options are discussed.

Prognostic implications of descending thoracic aorta dilation after surgery for aortic dissection

BACKGROUND

The present study assessed whether descending thoracic aorta growth can be measured reliably by volumetric analysis using multi-detector row computed tomography (MDCT) and whether growth influences the need for future aortic interventions in survivors of acute type A aortic dissection.

METHODS

A total of 51 patients (58 ± 11 years, 61% male) who underwent surgery for type A aortic dissection with ≥2 postoperative MDCT scans ≥5 months apart were included. Volumetric analysis of the descending thoracic aorta was performed with acceptable intraobserver variability. Growth of the complete, false and true lumen was estimated in ml/year and defined as slow growth (≤average growth) or fast growth (>average growth).

RESULTS

The complete lumen volume increased from 133 ± 8 ml to 163 ± 9 ml after 3.5 years follow-up (p < 0.001), with an average growth rate of 6.1 ml/year. The false lumen volume increased from 81 ± 7 ml to 106 ± 12 ml (p = 0.018) with an average growth rate of 2.8 ml/year. The true lumen changed only slightly from 59 ± 4 ml to 65 ± 8 ml (p = 0.205). Five-year freedom from descending thoracic aorta intervention was significantly lower in patients with above-average growth of the complete lumen (80 ± 9%) compared to slow growth (100%; p = 0.003). Similar observations were made for the false lumen (fast: 74 ± 12% vs. slow: 100%; p = 0.042).

CONCLUSIONS

Increased growth of the false lumen of the descending thoracic aorta after type A aortic dissection was associated with a higher risk of secondary interventions.

Left ventricular reverse remodeling after aortic valve surgery for acute versus chronic aortic regurgitation

AIMS

Extent of left ventricular (LV) reverse remodeling after aortic valve repair or replacement (AVR) may differ between patients operated for acute aortic regurgitation (AR) and chronic AR. The aim of this study was to compare changes in LV volumes and function between patients with acute and chronic AR who underwent AVR.

METHODS AND RESULTS

A total of 98 patients (54±15 years, 61% men) with acute (n=21) or chronic AR (n=77) were included in the present retrospective evaluation. LV volumes, LV ejection fraction, and global longitudinal strain indexed for LV end-diastolic volume (GLSi) were assessed preoperatively and after a median follow-up of 28 months (interquartile range: 17-66 months). Patients with acute AR tended to have smaller preoperative LV end-diastolic volume compared with chronic AR (156±15 vs 183±6 mL; P=.070). Both in patients with acute and chronic AR, significant LV reverse remodeling with sustained reduction in LV volumes occurred during follow-up with a significant smaller LV end-diastolic volume in acute AR compared with chronic AR (106±8 vs 128±5 mL; P=.032). Preoperative and postoperative LV ejection fractions were not significantly different between groups. In contrast, GLSi was better in patients with acute AR compared with chronic AR before AVR (-1.34±0.20 vs -0.96±0.07%/10 mL; P=.042) and during follow-up (-1.65±0.16 vs -1.29±0.07%/10 mL; P=.017).

CONCLUSIONS

After AVR, LV reverse remodeling occurs both in patients with acute and chronic AR. However, LV end-diastolic volume was more reduced and GLSi was more preserved during follow-up in acute AR than in chronic AR.

Comparison of Left Ventricular Volume and Ejection Fraction and Frequency and Extent of Aortic Regurgitation After Operative Repair of Type A Aortic Dissection Among Three Different Surgical Techniques

Differences in recurrence rate of aortic regurgitation (AR) and extent of left ventricular (LV) remodeling across the different surgical options in patients operated for type A aortic dissection remain unknown. The present evaluation compared the AR recurrence rate and changes in LV volumes and systolic function in valve-sparing aorta replacement (VSAR), supracoronary ascending aorta replacement (SCAR), and aortic valve and aorta replacement (AVAR). A total of 97 patients (58 ± 12 years, 62% men) with acute type A aortic dissection who underwent VSAR (n = 24), SCAR (n = 43), or AVAR (n = 30) were evaluated. Changes in LV volumes and function between postoperative and follow-up were compared using linear mixed models. Postoperative AR grades were not significantly different between groups. However, after median follow-up of 47 months, AR grade ≥2 was significantly more often observed in SCAR (55%) and VSAR (25%) compared to AVAR (0%, p <0.001). LV volumes remained stable in VSAR and AVAR but increased significantly in SCAR (LV end-diastolic volume: from 99 ± 4 to 131 ± 6 ml; p <0.001; LV end-systolic volume: from 49 ± 3 to 66 ± 5 ml; p = 0.002). In patients with recurrent AR grade ≥2 at follow-up, LV volumes increased, whereas patients without recurrent AR did not show significant LV dilatation. In conclusion, patients with acute type A aortic dissection who underwent SCAR or VSAR showed more frequently AR grade ≥2 recurrence compared to AVAR. However, only patients who underwent SCAR experienced adverse LV remodeling at follow-up. Recurrence of AR grade ≥2 was associated with adverse LV remodeling.

Porcine models of muscular dystrophy

Duchenne muscular dystrophy is a progressive, fatal, X-linked disease caused by a failure to accumulate the cytoskeletal protein dystrophin. This disease has been studied using a variety of animal models including fish, mice, rats, and dogs. While these models have contributed substantially to our mechanistic understanding of the disease and disease progression, limitations inherent to each model have slowed the clinical advancement of therapies, which necessitates the development of novel large-animal models. Several porcine dystrophin-deficient models have been identified, although disease severity may be so severe as to limit their potential contributions to the field. We have recently identified and completed the initial characterization of a natural porcine model of dystrophin insufficiency. Muscles from these animals display characteristic focal necrosis concomitant with decreased abundance and localization of dystrophin-glycoprotein complex components. These pigs recapitulate many of the cardinal features of muscular dystrophy, have elevated serum creatine kinase activity, and preliminarily appear to display altered locomotion. They also suffer from sudden death preceded by EKG abnormalities. Pig dystrophinopathy models could allow refinement of dosing strategies in human-sized animals in preparation for clinical trials. From an animal handling perspective, these pigs can generally be treated normally, with the understanding that acute stress can lead to sudden death. In summary, the ability to create genetically modified pig models and the serendipitous discovery of genetic disease in the swine industry has resulted in the emergence of new animal tools to facilitate the critical objective of improving the quality and length of life for boys afflicted with such a devastating disease.

Full-root aortic valve replacement with stentless xenograft achieves superior regression of left ventricular hypertrophy compared to pericardial stented aortic valves

BACKGROUND

Full-root aortic valve replacement with stentless xenografts has potentially superior hemodynamic performance compared to stented valves. However, a number of cardiac surgeons are reluctant to transform a classical stented aortic valve replacement into a technically more demanding full-root stentless aortic valve replacement. Here we describe our technique of full-root stentless aortic xenograft implantation and compare the early clinical and midterm hemodynamic outcomes to those after aortic valve replacement with stented valves.

METHODS

We retrospectively compared the pre-operative characteristics of 180 consecutive patients who underwent full-root replacement with stentless aortic xenografts with those of 80 patients undergoing aortic valve replacement with stented valves. In subgroups presenting with aortic stenosis, we further analyzed the intra-operative data, early postoperative outcomes and mid-term regression of left ventricular mass index.

RESULTS

Patients in the stentless group were younger (62.6 ± 13 vs. 70.3 ± 11.8 years, p < 0.0001) but had a higher Euroscore (9.14 ± 3.39 vs.6.83 ± 2.54, p < 0.0001) than those in the stented group. In the subgroups operated for aortic stenosis, the ischemic (84.3 ± 9.8 vs. 62.3 ± 9.4 min, p < 0.0001) and operative times (246.3 ± 53.6 vs. 191.7 ± 53.2 min, p < 0.0001) were longer for stentless versus stented valve implantation. Nevertheless, early mortality (0% vs. 3%, p < 0.25), re-exploration for bleeding (0% vs. 3%, p < 0.25) and stroke (1.8% vs. 3%, p < 0.77) did not differ between stentless and stented groups. One year after the operation, the mean transvalvular gradient was lower in the stentless versus stented group (5.8 ± 2.9 vs. 13.9 ± 5.3 mmHg, p < 0.0001), associated with a significant regression of the left ventricular mass index in the stentless (p < 0.0001) but not in the stented group (p = 0.2).

CONCLUSION

Our data support that full-root stentless aortic valve replacement can be performed without adversely affecting the early morbidity or mortality in patients operated on for aortic valve stenosis provided that the coronary ostia are not heavily calcified. The additional time necessary for the full-root stentless compared to the classical stented aortic valve replacement is therefore not detrimental to the early clinical outcomes and is largely rewarded in patients with aortic stenosis by lower transvalvular gradients at mid-term and a better regression of their left ventricular mass index.

Aortic valve and aortic root features in CT angiography in patients considered for aortic valve repair

BACKGROUND

The underlying mechanism of aortic regurgitation and aortic valve and root characteristics are associated with the durability of surgical repair.

OBJECTIVE

We investigated whether multidetector CT (MDCT) identifies the characteristics of the aortic valve and root that may be associated with the ability to perform successful surgical repair.

METHODS

Sixty-one patients with aortic regurgitation and/or aortic root pathology who were evaluated for aortic valve or root repair and underwent clinically indicated gated or nongated MDCT of the aortic valve and aortic root were included in the present analysis. Patients with endocarditis were excluded. MDCT data of aortic valve anatomy and calcification and thoracic aorta dimensions were analyzed.

RESULTS

The aortic valve and root was successfully repaired in 36 patients (55 ± 13 years; 61% male; median EuroSCORE II, 3.8%) whereas in 25 patients (56 ± 15 years; 52% male; median EuroSCORE II, 2.5%) repair was not attempted (n = 20) or valve repair was converted to aortic valve replacement during surgery (n = 5). In patients in whom repair was considered not possible or failed, there was a higher percentage of bicuspid aortic valves (48% vs 17%; P = .019), more severe commissural calcification, and more severe annular calcification.

CONCLUSION

The degree of commissural and annular calcification of the aortic valve determined by MDCT is inversely related to the ability to perform surgical valve repair instead of replacement. Similarly, bicuspid valve anatomy predicts failure to perform repair.

Application of Regent mechanical valve in patients with small aortic annulus: 3-year follow-up

Background

Aortic valve replacement (AVR) with a small aortic annulus is always challenging for the cardiac surgeon. In this study, we sought to evaluate the midterm performance of implantation with a 17-mm or 19-mm St. Jude Medical Regent (SJM Regent) mechanical valve in retrospective consecutive cohort of patients with small aortic annulus (diameter ≤ 19 mm).

Methods

From January 2008 to April 2011, 40 patients (31 female, mean age = 47.2 ± 5.8 years) with small aortic annulus (≤19 mm in diameter) underwent aortic valve replacement with a 17-mm or 19-mm St. Jude Medical Regent (SJM Regent) mechanical valve. Preoperative mean body surface area, New York Heart Association class, and mean aortic annulus were 1.61 ± 0.26 m², 3.2 ± 0.4, and 18 ± 1.4 mm respectively. Patients were divided into two groups, according to the implantation of 17 mm SJM Regent mechanical valve (group 1, n = 18) or 19 mm SJM Regent valve (group 2, n = 22). All patients underwent echocardiography examination preoperatively and at one year post-operation.

Results

There were no early deaths in either group. Follow-up time averaged 36 ± 17.6 months. The mean postoperative New York Heart Association class was 1.3 ± 0.6 (p < 0.001). By echocardiography, in group 1, the left ventricular ejection fraction (LVEF), left ventricular fraction shortening (LVFS), and the indexed effective orifice area (EOAI) increased from 43.7% ± 11.6%, 27.3% ± 7.6%, and 0.70 ± 0.06 cm²/m² to 69.8 ± 9.3%, 41.4 ± 8.3%, and 0.92 ± 0.10 cm²/m² respectively (P < 0.05), while the left ventricular mass index (LVMI), and the aortic transvalvular pressure gradient decreased from 116.4 ± 25.4 g/m², 46.1 ± 8.5 mmHg to 86.7 ± 18.2 g/m² , 13.7 ± 5.2 mmHg respectively. In group 2, the LVEF, LVFS and EOAI increased from 45.9% ± 9.7%, 30.7% ± 8.0%, and 0.81 ± 0.09 cm²/m² to 77.4% ± 9.7%, 44.5% ± 9.6%, and 1.27 ± 0.11 cm²/m² respectively, while the LVMI, and the aortic transvalvular pressure gradient decreased from 118.3 ± 27.6 g/m², 44.0 ± 6.7 mmHg to 80.1 ± 19.7 g/m², 10.8 ± 4.1 mmHg as well. The prevalence of PPM was documented in 2 patients in Group 1.

Conclusions

Patients with small aortic annulus and body surface area, experienced satisfactory clinical improvement after aortic valve replacement with modern SJM Regent bileaflet prostheses.

Midterm outcomes and quality of life of aortic root replacement: mechanical vs biological conduits

BACKGROUND

Aortic root replacement is a complex operation for severe aortic root pathology such as aneurysms and dissections with concomitant aortic valve disease. Biological and mechanical valve conduits are available.

METHODS

Early and midterm results were analyzed in patients undergoing aortic root replacement. From January 1, 1998, to May 31, 2007, 144 patients underwent aortic root replacement (Bentall procedures) with either a mechanical (n = 51) or a biological (n = 93) valve conduit. Cox proportional hazard analysis was used to determine whether valve type was an independent predictor of all-cause mortality, and analysis of covariance was used to compare general and disease-specific health-related quality-of-life scores.

RESULTS

Operative mortality was 2.1%. Median follow-up time was 40 months; 1- and 5-year survival rates for the mechanical group were 96.0% and 89.0%, respectively, vs 93.0% and 84.0% for the biological group. Valve type was not predictive of all-cause mortality, and valve-related complications were not significantly different between groups. At follow-up, 31.5% of patients in the biological group were on anticoagulant. General and disease-specific health-related quality-of-life scores were not significantly different between groups.

CONCLUSIONS

Aortic root replacement with either mechanical or biological valved conduits is a safe procedure. Morbidity, mortality, and adverse quality of life were not associated with the type of valve conduit. Further studies are required to assess long-term durability of biological valve conduits used for aortic root replacement.

Inflammation and infection in nine surgically explanted Medtronic Freestyle® stentless aortic valves

BACKGROUND

The Medtronic Freestyle valve is fixed in glutaraldehyde at zero pressure on the cusps and treated with alpha-amino oleic acid. This valve reportedly has excellent clinical and hemodynamic results, but little has been reported about its long-term pathology.

METHODS AND RESULTS

Nine Freestyle valves explanted between 2003 and 2005 were reviewed to assess the reasons for bioprosthesis failure (six implanted at our institution). All valves were examined in detail, using histochemistry and immunohistochemistry to identify the cellular response. One Freestyle valve, explanted for mitral valve endocarditis on the fifth postoperative day, was excluded from analysis. Average implant duration was 52.8+/-35.5 months. Four valves were explanted for infective endocarditis, three for aortic insufficiency, two for aortic stenosis with cusp calcification seen in five valves, pannus and thrombus in all valves and a chronic inflammatory reaction involving the xenograft arterial wall seen in eight of nine valves. This was associated with significant damage to the porcine aortic wall in seven cases, and cusp myocardial shelf damage in six cases.

CONCLUSIONS

In this series of valves, we found (1) infective endocarditis; (2) pannus, thrombus, and calcification; and (3) unusual and significant inflammatory reaction and aortic tissue damage, which could by itself lead to aortic incompetence.

Late Disruption of a Freestyle Stentless Bioprosthesis Used for Repair of Sinus of Valsalva Aneurysm of Noncoronary Cusp

We present a case of disruption of the porcine aortic wall of the 27-mm Freestyle stentless bioprosthesis 5 years after the subcoronary implantation to exclude the sinus of Valsalva aneurysm of the noncoronary cusp. At the urgent reoperation, the inflow suture line was found to be intact, and therefore a new stented valve was sutured with the inflow Dacron cuff after removal of ruptured valve. The subcoronary implantation technique creates a cavity between the prosthetic and native aortic walls filled with hematoma. The outflow suture line dehiscence caused blood flow into the cavity, porcine aortic wall rupture, and leaflet destruction.

Coronary Insufficiency After Stentless Aortic Root Replacement: Risk Factors and Solutions

BACKGROUND

Coronary insufficiency is a dreaded complication of total aortic root replacement (ARR) with few defined risk factors. This study describes the incidence, risk factors, management options, and outcomes of this condition after ARR with stentless porcine valves.

METHODS

The study consisted of a retrospective analysis of 503 patients (mean age, 68.9 +/- 10.2 years) undergoing stentless porcine total ARR (Medtronic Freestyle and St. Jude Toronto) between the years 1993 and 2005 at a single institution. Coronary insufficiency was defined as the need for unplanned bypass grafting during, or after removal from cardiopulmonary bypass to correct wall motion abnormalities, arrhythmias, or right ventricular failure in the absence of known obstructive coronary disease.

RESULTS

A total of 13 cases of right coronary artery and no cases of left coronary insufficiency were identified (overall incidence 13 of 503, 2.6%). All were treated with aortocoronary bypass grafting to the right coronary artery using saphenous vein. Compared with patients who did not have coronary insufficiency, patients with this complication were more likely to be female (11 of 13, 85%, versus 201 of 490, 41%; p = 0.006), had higher mean body mass index (34.6 +/- 12.0 kg/m2 versus 28.3 +/- 3.8 kg/m2, p = 0.04), and were implanted with smaller prostheses (23.9 +/- 2.1 mm versus 25.6 +/- 2.4 mm, p = 0.026), a finding not explained by the preponderance of female sex. Mean age, ejection fraction, and other demographic variables were similar. Despite longer cardiopulmonary bypass times (238 +/- 61 minutes versus 180 +/- 35 minutes, p = 0.005), operative mortality was not significantly different (1 of 13, 7.7%, versus 29 of 490, 5.9%; p = not significant).

CONCLUSIONS

Coronary artery insufficiency is uncommon after stentless aortic root replacement and more often affects the right coronary artery. Risk factors appear to be female sex, higher body mass index, and small aortic root. Preventive measures include recognition of coronary orientation, routine valve rotation, and adequate coronary button mobilization. When this complication occurs, good outcomes can still be obtained with early recognition and prompt bypass grafting.

Short-Term and Intermediate-Term Outcomes of Aortic Root Replacement with St. Jude Mechanical Conduits and Aortic Allografts

BACKGROUND

Few studies have directly evaluated outcomes in patients undergoing aortic root replacement with St. Jude mechanical conduits or aortic allografts (ALLO), yet both approaches have been advocated. The purpose of this study was to provide a detailed description of outcomes in a large series of aortic root replacements performed with either St. Jude mechanical conduits or aortic allografts.

METHODS

A retrospective analysis was performed on 172 consecutive adult patients undergoing aortic root replacement with either St. Jude mechanical conduits (n = 73) or aortic allografts (n = 99) from January 1990 to December 2002. Maximal follow-up was 15 years, and median follow-up was 5 years.

RESULTS

Both groups were similar with regard to median age, preoperative ejection fraction, and New York Heart Association class. The aortic allograft patient group had a higher proportion (p < 0.05) of women (43% versus 18%), prior sternotomies (52% versus 26%), preoperative renal failure (9% versus 1%), and cerebrovascular disease (16% versus 4%). Operative indications for the aortic allograft group were more frequently endocarditis (29% versus 3%; p < 0.0001) and prosthetic valve dysfunction (13% versus 1%; p < 0.01), and less frequently annuloaortic ectasia (34% versus 60%; p < 0.001) or aortic dissection (3% versus 26%; p < 0.0001). Concomitant coronary artery bypass grafting or other valve surgery was performed in 30% of patients in both groups. Incidence of early postoperative complications, including bleeding, stroke, renal failure, and respiratory failure, was similar in both groups. Thirty-day mortality was 5.5% in the St. Jude mechanical conduit group and 8.1% in the aortic allograft group (p = 0.4). Unadjusted actuarial survival at 1, 5, and 10 years was 90%, 81%, 67%, and 86%, 70%, 67%, for the St. Jude mechanical conduit and aortic allograft groups, respectively (p = 0.09). Event-free survival at 1 and 5 years was similar for both groups (p = 0.4). By multivariate analysis, New York Heart Association class III or IV, emergently performed aortic root replacement, and postoperative respiratory failure, but not valve conduit type (p = 0.3), were independent predictors of mortality.

CONCLUSIONS

Aortic root replacement can be safely performed with either allograft or mechanical conduits, even in the setting of acute dissection, redo sternotomy, or endocarditis.

Mid term outcome and quality of life after aortic valve replacement in elderly people: mechanical versus stentless biological valves

OBJECTIVE

To assess the benefit for patients older than 65 years of aortic valve replacement with stentless biological heart valves in comparison with mechanical valves.

DESIGN

Multiple regression analysis of a retrospective follow up study.

SETTING

Single cardiothoracic centre.

PATIENTS

Between 1996 and 2001, 392 patients with a mean age of 74 years underwent aortic valve replacement with stentless Freestyle bioprostheses or mechanical St Jude Medical prostheses.

MAIN OUTCOME MEASURE

Operative mortality and morbidity, postoperative morbid events, mid term survival, and New York Heart Association (NYHA) class improvement, and quality of life.

RESULTS

No significant differences were found between patients receiving stentless biological valves and patients receiving mechanical prostheses. However, analysis of subgroups showed that patients older than 75 years with mechanical valves had an increased risk of major bleeding events (p = 0.007). Patients requiring anticoagulation by means of coumarin had a twofold increased risk of an impaired emotional reaction (p = 0.052). However, for patients who received a mechanical valve for severe combined aortic valve disease a survival advantage (p = 0.045) and a decreased risk of prolonged ventilation (p = 0.001) was observed. On the other hand, patients receiving a stentless bioprosthesis had an increased risk of a prolonged stay in intensive care (p = 0.04) and stroke (p = 0.01) if they had severely reduced cardiac function (NYHA class IV).

CONCLUSIONS

Elderly people receiving stentless bioprostheses benefit emotionally because of the avoidance of coumarin. However, in patients with severe hypertrophied ventricles and extraordinary calcifications, stentless bioprostheses should be chosen with caution.

St. Jude Medical Toronto biologic aortic root prosthesis: Early FDA phase II IDE study results

BACKGROUND

Several biological aortic root replacement techniques have distinct advantages over mechanical composite root replacement including better valvular hemodynamic characteristics and the lack of need for anticoagulation. Current biological root replacement options lack proven long-term durability or are limited by technical or practical concerns. We report the early results from a phase II multicenter clinical trial of the porcine St. Jude Toronto Bioprosthesis with BiLinx (Toronto root).

METHODS

176 Toronto roots were implanted as total aortic root replacement from August 2001 through August 2003. Concomitant cardiac procedures including coronary artery bypass grafting (31%) and ascending aortic replacement (55%) were performed in 74%. Patients were followed clinically and were examined with an echocardiogram at discharge, 6 months, 12 months, and yearly thereafter. Root sizes implanted included 29 mm in 38%, 27 mm in 30%, 25 mm in 20%, 23 mm in 10%, and 21 mm in 2.2%.

RESULTS

There are 205 patient years of follow-up through October 2003. Operative mortality was 3.9% (none were valve related) and late mortality was 4%. Operative stroke rate was 1.1% and late stroke rate was 0.6%. Endocarditis developed in 1 patient. Freedom from aortic regurgitation is to date 100% at discharge, 6 months, and 1 year postimplant. Reoperation of the aortic valve/root was not required in any patient. Six-month mean transvalvular gradients for 21-29 mm valves were 12.8, 8.8, 5.3, 4.9, and 4.7 mm Hg, respectively.

CONCLUSIONS

Aortic root replacement with the Toronto root is safe and provides superb transvalvular hemodynamics with freedom from anticoagulation. The Toronto root seems widely applicable for all types of aortic root pathology and these early data offer very encouraging results. Long-term follow-up is required.

A new equine pericardial stentless valve

OBJECTIVE

Small aortic valve replacement remains a challenging hemodynamic problem. A new bioprosthesis (3F Therapeutics, Lake Forest, Calif) was designed to further improve the hemodynamic performance currently achieved with stentless bioprostheses. This valve consists of a tubular structure assembled from 3 equal sections of equine pericardial material, with virtually no foreign material except for a thin polyester ring. Its hemodynamic performance was compared with that of a commercially available stentless prosthesis in a bovine model.

PATIENTS AND METHODS

Twelve calves (55 +/- 2.8 kg) received a 19-mm 3F valve (3F group, n = 6) or a 19-mm stentless control valve (control group, n = 6). The animals were fully equipped for hemodynamic monitoring and transvalvular gradient measurements. After implantation, dopamine was infused in increasing doses, and the hemodynamic values were recorded at each step of 100-microg/min increase. Linear regression analysis was applied for group comparison of each variable.

RESULTS

The mean transvalvular gradient at 4.5 L/min was 3.48 +/- 0.14 mm Hg (95% confidence interval) in the 3F group and 5.72 +/- 0.28 mm Hg in the control group (P <.0001) and at 6.5 L/min, 7.4 +/- 1.55 mm Hg, and 11.13 +/- 0.18 mm Hg, respectively (P <.0001). The effective orifice area at 4.5 L/min was 2.4 +/- 0.03 cm(2) in the 3F group and 1.86 +/- 0.02 cm(2) in the control group (P <.0001) and at 6.5 L/min, 2.41 +/- 0.04 cm(2), and 1.96 +/- 0.02 cm(2), respectively (P <.0001).

CONCLUSIONS

This new bioprosthesis without a stent and without a supporting wall that has its commissures fixed directly to the aorta outperforms in vivo standard stentless prostheses in the immediate postimplant period.

Aortic root replacement with stentless xenograft for aortic dissection

This paper reviewed aortic root replacement with a stentless xenograft for Stanford Type A aortic dissection. Total aortic arch replacement plus aortic root reconstruction with a stentless xenograft was conducted in 2 patients with acute aortic dissection. In another 2 patients, aortic root replacement with a bioprosthesis was performed for chronic redissection of the aortic root which might be associated with the previous use of gelatin-resorcin-formalin glue. Full root replacement using this device is safe, reliable, reproducible, and technically less demanding. This device also provides a radical option for acute aortic dissection even in patients requiring concomitant aortic arch and root replacement.

Electrocardiographically gated multi-detector row CT for assessment of valvular morphology and calcification in aortic stenosis

PURPOSE

To evaluate the applicability and image quality of nonenhanced and contrast material-enhanced multi-detector row computed tomography (CT) combined with retrospective electrocardiographic (ECG) gating for visualization of the aortic valve, determination of aortic valve morphology and diameter of the aortic valve annulus, and assessment of the degree of valvular calcification in patients with aortic valve stenosis, as compared with results of surgery and echocardiography.

MATERIALS AND METHODS

Prior to surgical valve replacement, 25 patients with aortic valve stenosis and sinus rhythm underwent nonenhanced (n = 15) and contrast-enhanced (n = 25) retrospectively ECG-gated multi-detector row CT. Two readers working in consensus evaluated image quality and assessed valvular morphology and the degree of valvular calcification. In addition, the diameter of the aortic valve annulus was measured. Results were compared with surgical and echocardiographic findings by using the paired sign test, kappa statistics, and the method of Bland and Altman.

RESULTS

The aortic valve could be visualized nearly free of motion artifacts on all multi-detector row CT images. Image quality and diagnostic confidence for classification of aortic valve morphology were significantly superior on contrast-enhanced rather than nonenhanced images (P =.004 and P =.006, respectively). Nonenhanced and contrast-enhanced CT showed good agreement with surgical findings with regard to quantification of the degree of aortic valve calcification (kappa = 0.77 and kappa = 0.74, respectively). Measurement of the diameter of the aortic valve annulus was more reliable on contrast-enhanced images.

CONCLUSION

Contrast-enhanced retrospectively ECG-gated multi-detector row CT allows determination of aortic valve morphology, measurement of the diameter of the aortic valve annulus, and assessment of the degree of aortic valve calcification in patients with aortic stenosis.

Eight-year results of aortic root replacement with the freestyle stentless porcine aortic root bioprosthesis

BACKGROUND

Stentless porcine aortic valves offer several advantages over traditional valves. Among these are superior hemodynamics, laminar flow patterns, lack of need for anticoagulation, and perhaps improved durability.

METHODS

One hundred four patients were operated on from September 17, 1992, to October 31, 1997, as part of a multicenter worldwide investigation of the Medtronic Freestyle stentless porcine bioprosthesis. All patients received a total aortic root replacement. The patients were evaluated postoperatively at discharge, at 3 to 6 months, and yearly by clinical examination and color flow Doppler echocardiography.

RESULTS

Operative mortality was 3.9%. No patient experienced structural valve deterioration, nonstructural deterioration, perivalvular leak, or unacceptable hemodynamic performance. At 8 years, survival was 59.8%. Freedom from thromboembolic complications was 83.3%. Freedom from postoperative endocarditis was 96.9%. Freedom from reoperation was 100%. Mean systolic gradients did not change over the time period studied. They were 6.4 +/- 3.8 mm Hg at 1 year and 6.7 +/- 2.6 mm Hg at 8 years. Correspondingly, effective orifice area was 1.9 +/- 0.7 cm2 at 1 year and 1.8 +/- 0.8 cm2 at 8 years. The incidence of any aortic insufficiency also did not change over the length of follow-up. At 1 year, 98% of patients had no or trivial aortic insufficiency and 2% had mild aortic insufficiency. At 8 years, 100% of patients evaluated were free of any aortic insufficiency.

CONCLUSIONS

The Medtronic Freestyle aortic root bioprosthesis can be used safely to replace the aortic root or aortic valve for aortic valve and aortic root pathology. Total root replacement allows optimal hemodynamic performance with no significant aortic regurgitation. Results up to 8 years show excellent survival and no signs of degeneration. Further follow-up is still needed to determine valve durability.

Dilation of the sinotubular junction causes aortic insufficiency after aortic valve replacement with the Toronto SPV bioprosthesis

OBJECTIVE

This study was undertaken to examine the causes of late aortic insufficiency in patients who had aortic valve replacement with the Toronto SPV bioprosthesis (St Jude Medical, Inc, St Paul, Minn).

METHODS

From 1991 to 1996, 174 patients with a mean age of 63 +/- 11 years underwent aortic valve replacement with the Toronto SPV bioprosthesis and were evaluated annually by Doppler echocardiographic studies to assess valve function. The diameters of the aortic root were retrospectively measured in all patients who had aortic insufficiency and also in a random sample of 23 patients without aortic insufficiency. The mean follow-up was 5.8 years (range 4 to 9 years).

RESULTS

Aortic insufficiency greater than 1+ developed in 19 patients. The diameter of the sinotubular junction increased in these patients and did not change in those without aortic insufficiency. The ratio between the diameter of the sinotubular junction and the size of the Toronto SPV bioprosthesis increased in patients who had aortic insufficiency and did not change in those without aortic insufficiency. Both 2-way analysis of covariance and analysis by a mixed linear model demonstrated a significant difference in slopes between the patients with aortic insufficiency greater than 1+ and in those without insufficiency for the ratio of the diameter of the sinotubular junction/diameter of the Toronto SPV relationships over time (aortic insufficiency. Year; P <.001). Structural valve deterioration was observed in 5 valves, and in 4 of them the sinotubular junction of the aortic root had dilated. The freedom from structural valve deterioration was 99% +/- 1% for patients without aortic insufficiency and 82% +/- 12% for those with aortic insufficiency of more than 1+ at 8 years (P =.004). One patient had moderate aortic insufficiency without structural valve deterioration and dilation of the sinotubular junction.

CONCLUSIONS

Dilation of the sinotubular junction causes aortic insufficiency after aortic valve replacement with the Toronto SPV bioprosthesis and increases the risk of structural valve deterioration. Banding the sinotubular junction may prevent dilation and enhance the durability of this valve.

Resolution of perivalvular hematoma of the Freestyle stentless aortic root bioprosthesis implanted with a subcoronary technique

The modified subcoronary technique is frequently used to implant the Freestyle aortic root bioprosthesis because of its ease. This technique is primarily associated with hematoma in the potential space between the prosthetic and native aortic walls. We report a case of resolution of perivalvular hematoma around the Freestyle valve 6 months after implantation in a patient with aneurysm of the noncoronary sinus of Valsalva. During follow-up, the patient underwent no significant changes in pressure gradient or degree of regurgitation. Although long-term results are not yet known, the subcoronary technique may be a feasible alternative for patients with aneurysms in the sinus of Valsalva to exclude it, unless the sinotubular junction and aortic annulus are intact.

Role of biologic glue repair of proximal aortic dissection in the development of early and midterm redissection of the aortic root

BACKGROUND

Redissection of the aortic root after supracommissural aortic graft replacement with reapproximation of the layers of the dissected aortic root is relatively rare. Causes and surgical treatment of this lesion remain controversial.

METHODS

From January 1983 to September 2000, 130 patients had emergency operation for acute type A aortic dissection. Of them, 57 patients underwent root reconstruction using biologic glues and 4 patients (7.0%) developed redissection of the aortic root associated with moderate to severe aortic regurgitation 5 to 27 months after the initial operation. In all patients, the proximal false lumen was obliterated with infusion of gelatin-resorcinol-formaldehyde (GRF) glue or BioGlue and the aorta was reinforced with Teflon felt strip or Surgicel placed on its outside wall.

RESULTS

During reoperation, the noncoronary aortic sinus was found to be redissected in all patients with the dissection extending retrogradely to the aortic annulus. This resulted in aortic regurgitation with prolapse of the noncoronary cusp because the proximal suture line dehisced. Histopathology showed disappearance of the nuclei of the medial smooth muscle cells, suggesting tissue necrosis at the site of GRF glue application. The lesions were treated successfully with full root replacement using a freestyle heterograft bioprosthesis or a composite graft prosthesis.

CONCLUSIONS

The use of biologic glues for reapproximating the layers of the dissected aortic root is associated with a certain amount of risk of aortic wall necrosis. Therefore, care should be taken to ensure proper use of these glues. Full root replacement could be a preferable technique for treating redissection of the aortic root.

The freestyle stentless aortic bioprosthesis: more about the subcoronary technique

Two years after aortic valve replacement with a Freestyle stentless aortic xenograft using the partial scallop inclusion technique, late prosthetic valve endocarditis developed with abscess formation in the space between the porcine and native human aortic wall. The presence of such a periprosthetic dead space exposes the patient to increased postoperative pressure gradients and the risk of superinfection.

Stentless aortic valve replacement with Freestyle or Toronto SPV: an early comparison

BACKGROUND

Stentless aortic xenograft valves have been developed to overcome the disadvantages of conventional stented prostheses. We have implanted two new aortic bioprostheses: the Medtronic Freestyle and the St. Jude Toronto SPV. Early results are compared.

METHODS

Forty-four Freestyle valves were implanted using a freestanding total root technique. Fourteen subcoronary Toronto SPV bioprostheses were implanted. Sixty-four percent of both groups (28 of 44 Freestyle and 9 of 14 Toronto SPV) underwent concurrent procedures.

RESULTS

Ischemic time was 117 +/- 21 minutes for Freestyle and 124 +/- 19 minutes for Toronto SPV. There were no operative deaths or valve-related reoperations. Aortic valve area was 1.83 +/- 0.51 cm2 for Freestyle and 1.80 +/- 0.51 cm2 (p = 0.89) for Toronto SPV. Transvalvular gradient was 8.03 +/- 4.09 mm Hg for Freestyle and 12.4 +/- 1.82 mm Hg (p = 0.002) for the Toronto SPV. Aortic regurgitation was not experienced in any Freestyle patients, while Toronto SPV patients were graded as none to trace 79% (11 of 14), mild 14% (2 of 14), and moderate 7% (1 of 14).

CONCLUSIONS

Aortic valve replacement with the Freestyle and Toronto SPV required equal time for implantation and had equal effective orifice areas. Freestyle had lower transvalvular gradient and less aortic insufficiency without increasing morbidity or mortality.

Normalization of left ventricular dimensions after Ross operation with aortic annular reduction

BACKGROUND

Fifty-seven patients (August 1995 to November 1998) with a dysplastic dilated aortic root, a relative contraindication to the Ross operation, received an extended Ross operation with aortic annulus reduction and external cuff fixation (age 14-54 years). To assess the efficacy of these operations, echocardiographic assessment of autograft valve function and left ventricular function and dimensions were reviewed.

METHODS

Preoperative and postoperative assessment of 27 patients with aortic insufficiency (AI group) and 30 patients with aortic stenosis (>20 mm Hg peak gradient) and aortic insufficiency (AS group) were compared. Aortic annulus size, valvular gradient, valve insufficiency, left ventricular dimensions at end-systole and end-diastole, left ventricular fractional shortening, and left ventricular mass were assessed.

RESULTS

There was one late death. Aortic annulus size, degree of AI, left ventricular internal dimensions, and left ventricular mass were all significantly reduced (p<0.05) postoperatively in the AI group. Mean peak pressure gradients for this group were 6.8+/-6.7 mm Hg before operation and 8.7+/-6.4 mm Hg at 1 year after operation. Peak pressure gradient, aortic annulus size, degree of AI, left ventricular internal dimensions, and left ventricular mass were significantly reduced (p<0.05) in the AS group. Mean fractional shortening was within normal limits pre- and postoperatively for both groups.

CONCLUSIONS

Regression of left ventricular dilatation and hypertrophy, excellent autograft valve function, and survival suggest that this modification of the Ross operation may be offered to patients with a dysplastic aortic root requiring aortic valve replacement.