Subcoronary Technique Research Articles

Time Course of Aortic Valve Function and Root Dimensions After Subcoronary Ross Procedure for Bicuspid Versus Tricuspid Aortic Valve Disease

Background The freestanding aortic root, which is the currently preferred operative technique for pulmonary autografts, is reported to dilate and potentially promote aortic insufficiency, which has led to a controversial debate on the appropriate surgical technique, especially for congenital bicuspid aortic valve disease. Desirable data on the time course of valve function and root dimensions for the alternative subcoronary technique comparing bicuspid and tricuspid aortic valve disease are scarce. Methods and Results Echocardiographic examinations of 31 patients with congenital bicuspid aortic valve disease (group A; age 50.5±11.0 years) and 51 patients with acquired tricuspid aortic valve disease (group B; age 48.1±15.7 years) who were operated on between June 1994 and August 1998 were performed twice postoperatively. At first and second follow-up, respectively, maximum (mean) pressure gradients were 6.0±2.0 (3.6±1.0) and 5.1±2.1 (2.9±1.1) mm Hg in group A and 6.5±3.5 (3.9±1.9) and 5.0±1.7 (2.9±1.0) mm Hg in group B ( P >0.05 between groups). In group A, grade 0 aortic insufficiency at first and second follow-up occurred in 8 and 7 patients, respectively, grade 0-I in 12 and 9 patients, grade I in 9 and 11 patients, grade I-II in 1 and 0 patients, and grade II in 1 and 4 patients; in group B, grade 0 aortic insufficiency occurred in 16 and 18 patients, grade 0-I in 16 and 8 patients, grade I in 17 and 21 patients, grade I-II in 0 and 1 patient, and grade II in 0 and 1 patient ( P >0.05). Aortic insufficiency decreased in 10 patients (17%). However, there was an overall tendency for aortic insufficiency to increase over time (n=23, 38%), although it remained subclinical. Aortic root dimensions did not differ between groups and were constant during follow-up. Conclusions This study provides some evidence that the function of the subcoronary pulmonary autograft in bicuspid aortic valve disease is excellent, with stable root dimensions, and is not different from that of tricuspid aortic valves at least up to 5.5 years postoperatively, which suggests the subcoronary technique should be reconsidered.

Pulmonary homograft: Should it be used in the aortic position?

Objective: Retrospective analysis was performed to determine the suitability of pulmonary homograft as an aortic valve substitute. Methods: From January 1994 through June 1999, 147 patients (mean age, 32.2 ± 17.3 years) underwent aortic valve replacement with either an aortic homograft (group 1: n = 103, 25 fresh antibiotic preserved and 78 cryopreserved) or a pulmonary homograft (group 2: n = 44, 11 antibiotic preserved and 33 cryopreserved). In group 1 a scalloped subcoronary technique was used in 64 patients, and a root replacement technique was used in 39 patients. In group 2 the scalloped subcoronary technique was used in 34 patients, and the root replacement technique was used in 10 patients. Results: There were 131 operative survivors (group 1 = 91; group 2 = 40). Follow-up ranged from 2 to 62 months. In group 1 none of the patients had significant aortic regurgitation during the hospital stay. Three patients (all having undergone the scalloped subcoronary technique) had moderate aortic regurgitation after 6 to 32 months. In group 2, 10 patients (9 having undergone the scalloped subcoronary technique and 1 having undergone the root replacement technique) developed significant regurgitation: 2 intraoperatively, 5 in the early postoperative period before discharge from the hospital, and 3 during late follow-up 6 to 12 months postoperatively. Among the various risk factors analyzed for overall homograft failure, use of a pulmonary homograft was the single independent predictor of valve failure (odds ratio, 8.6; 95% confidence interval, 1.9-39; P =.006). Conclusion: Pulmonary homograft, when inserted by means of a scalloped subcoronary technique, is not a suitable aortic valve substitute. (J Thorac Cardiovasc Surg 2000;120:148-55)

Aortic valve replacement with the freestyle stentless bioprosthesis with respect to spacial orientation of patient coronary ostia

Objective: This study evaluates our results for safety and efficacy of aortic valve replacement using the Freestyle bioprosthesis (Medtronic, Inc, Minneapolis, Minn) with a new modified subcoronary implantation technique. This technique takes into account the spacial orientation of the stentless bioprosthesis in the aortic root with respect to the patient’s coronary ostia rather than the native commissures. Methods: Fifty-two consecutive patients with predominant aortic valve stenosis underwent aortic valve replacement with a Freestyle bioprosthesis by means of the described modified subcoronary technique over a 15-month period. Fifty of them were followed up by means of echocardiography at discharge, 6 months, and 1 year. There were 19 men and 31 women, with a mean age of 76 ± 7 years (range, 58-87 years). Valve size ranged from 21 to 27 mm. Results: Patients with bicuspid aortic valves had a significantly larger angle between both coronary ostia than patients with tricuspid aortic valves ( P = .0001). The peak and mean systolic gradients decreased significantly during the first postoperative year for each valve size ( P ≤ .001), and the effective valve areas increased significantly during this time interval for each valve size ( P ≤ .01). Only 13 patients had aortic insufficiency at discharge, which was trivial in 9 and mild in 4 patients. The prevalence of trivial aortic insufficiency decreased during the first postoperative year, and that of mild aortic insufficiency remained unchanged. The sinotubular junction diameter was significantly greater than that of the aortic anulus for each valve size before operation ( P < .001). The sinotubular junction diameter decreased significantly after aortic valve replacement and remained unchanged during the first postoperative year for each valve size ( P < .001). Conclusions: Aortic valve replacement with the Freestyle bioprosthesis using the modified subcoronary technique, which takes into account the spacial orientation of the patient’s coronary ostia, has hemodynamic results similar to those of other series with different subcoronary implantation techniques. This technique is reproducible, safe at the coronary ostial level, and effective in accommodating variability in angles between human coronary ostia, ranging from 130° to 170°. Moreover, the great preoperative discrepancies between aortic anulus and sinotubular junction diameters are corrected immediately after operation. (J Thorac Cardiovasc Surg 2000;119:1185-93)

Size and distensibility of the aortic root and aortic valve function after different techniques of the Ross procedure

Objectives: In the Ross procedure, 3 different techniques are used for aortic valve replacement with the pulmonary autograft: freestanding root, inclusion, and subcoronary implantation. The objective of this study was to evaluate echocardiographically the influence of the particular operative technique on dimension, distensibility, and valve function. Methods: Between February 1990 and August 1998, the Ross procedure was performed in 111 patients (mean age, 48.6 ± 14.1 years; range, 15.2-70.6 years), with 1 early and 1 late death, 1 autograft replacement, and 1 patient lost to follow-up. The remaining patients underwent the freestanding root (n = 9 patients), inclusion (n = 14 patients), and subcoronary techniques (n = 84 patients). Echocardiography was performed at a mean follow-up of 26 ± 21.3 months after operation and was compared with the echocardiographic findings of the control subjects (n = 10 subjects). Root sizes were measured at the level of the anulus, sinus, and supra-aortic ridge; the distensibility was calculated as pressure strain elastic modulus and percent change of radius. Results: Size and distensibility of the aortic root were normal, except for a larger diameter at the sinus level in the root technique in comparison to the subcoronary technique ( P < .05; maximum diameter, 41.3 ± 8.6 mm vs 32.6 ± 4.0 mm). Aortic valve function was comparable among groups with low pressure gradients and most patients with no or trace aortic insufficiency. Conclusions: The freestanding root, inclusion, and subcoronary techniques in the Ross procedure provide comparable excellent hemodynamics, normal root size, and distensibility, except for the enlarged sinus diameter in the freestanding root. These results may have some impact on the operative procedure and follow-up investigations. (J Thorac Cardiovasc Surg 2000;119:990-7)

Early experience of aortic valve replacement with the Freestyle stentless aortic bioprosthesis in elderly patients.

Stentless bioprostheses have been gaining popularity in recent years as hemodynamically superior alternatives to conventional stented bioprostheses. Between July 1996 and November 1998, 13 patients with aortic valve disease, 7 males and 6 females with a mean age (+/- SD) of 68 +/- 5 years, underwent an aortic valve replacement using the Medtronic Freestyle aortic bioprosthesis. The predominant lesions were stenosis in 8 patients and regurgitation in 5, while 2 patients had endocarditis. The operation was performed by a subcoronary technique in 9, root-inclusion technique in 3, and full root technique in 1 patient. Throughout the follow-up periods (with average follow-up period of 20.6 months), there was no hospital mortality, though there was one late death of unknown cause. The New York Heart Association class improved in all patients. The peak transvalvular gradient decreased from 18.4 +/- 9.8 to 12.6 +/- 9.6 mmHg, and the effective valve orifice area increased from 2.30 +/- 0.96 to 2.59 +/- 1.05 cm2 between the 1-month and the 6-month follow-up examinations. In patients with aortic regurgitation, the left ventricular end-diastolic/end-systolic volume index significantly decreased from 147 +/- 36/62 +/- 19 to 73 +/- 26/33 +/- 14 ml/m2 at 1 month after the operation. The left ventricular mass index also significantly decreased from 189 +/- 26 to 143 +/- 30 g/m2 in patients with aortic regurgitation and from 171 +/- 28 to 144 +/- 30 g/m2 in those with aortic stenosis. Although long-term follow-up is required for further evaluation, the early results appeared to indicate that the Freestyle aortic bioprosthesis was suitable for elderly patients requiring aortic valve replacement.

Influence of sizing and subcoronary implantation technique on the function of porcine aortic homografts

The function and longevity of the homograft aortic valve may be influenced by valve size and subcoronary implantation technique. Dynamic function and leaflet configuration of the porcine aortic valve were analysed first in it snatural root in a left heart simulator using glycerol at 120/80 mm Hg pressure and 4 l min-1 Cardiac Output (C.O.). Then the valve was implanted in the porcine root and studied: Group I (n = 4) 1-2 mm smaller, Group II (n = 8) 3-4 mm smaller and Group III (n = 4) 5-7 mm smaller donor valve than the recipient. A silicone rubber mould of the implanted valve was made and analysed. In the donor aortic root the commissural expansion for 0 to 80 mm Hg pressure was 42% which was reduced significantly in all assemblies. Group I showed the largest decrease in the orifice area (OA). In Group III decrease in the OA was less, however, two of the four valves had aortic insufficiency (AI). In Group II decrease in the OA was only 13% and there was no AI. During opening the leaflet surface was smooth and freeof wrinkles in the intact valve, but had creases and folds in all three groups. All implanted valves had an indentation along the suture line disrupting the leaflet-sinus continuity. Hence, to enhance valve longevity, donor valve 3-4 mm smaller than the recipient should be chosen and the implantation technique modified to preserve the leaflet-sinus continuity.

Echocardiographic Parameters of the Freestyle Stentless Bioprosthesis in Aortic Position: The European Experience

The objective of this study was to determine normal Doppler and 2-dimensional characteristics of the Freestyle stentless aortic bioprosthesis. The Freestyle aortic bioprosthesis is a new type of aortic xenograft, and experience is limited. We therefore determined the normal range of echocardiographic and Doppler examinations of this valve. Three hundred thirty-nine consecutive patients with a Freestyle aortic bioprosthesis underwent an echocardiographic and Doppler examination according to a common protocol. Investigations were done within 4 weeks after operation, after 3 to 6 months, and after 1, 2, and 3 years. With a valve size from 19 to 27 mm, mean gradients decreased from 7.9 ± 5.1 mm Hg at discharge to 5.5 ± 3.8 mm Hg after 3 to 6 months ( P < .001). Thereafter, gradients remained stable. Effective orifice area 1 year after implantation was 1.59 ± 0.58 cm 2 for the 21-mm valves, 1.92 ± 0.74 cm 2 for the 23-mm valves, 2.03 ± 0.64 cm 2 for the 25-mm valves, and 2.52 ± 0.72 cm 2 for the 27-mm valves ( P < .001). The performance index, the ratio of the measured effective orifice area in the patient divided by the effective orifice area measured in vitro, increased from 67% ± 20% at discharge to 82% ± 29% after 1, 2, and 3 years. Performance index was especially very high in the smaller-sized valves. After implantation with the subcoronary technique or root-inclusion technique, small cavities could be seen between the native aortic root and the Freestyle valve. Doppler values were evaluated for the Freestyle stentless porcine bioprostheses in the aortic root. Gradients appear to be close to those measured in native valves over a time period of 3 years. (J Am Soc Echocardiogr 1999;12:729-35.)

Clinical and hemodynamic performance of the freestyle aortic root bioprosthesis

Background. The objective of this study is to assess the clinical and hemodynamic performance of a stentless porcine bioprosthesis, the Freestyle aortic root bioprosthesis. Methods. Consenting patients requiring isolated aortic valve or aortic root replacement received the Freestyle bioprosthesis. Clinical follow-up and echocardiographic data were obtained at discharge, 3 to 6 months, 1 year, and annually thereafter. Results. Two hundred seventy-six patients received a Freestyle aortic root bioprosthesis between January 1993 and July 1997. The mean age was 67.7 years. Preoperatively, 86.3% were either New York Heart Association class III or IV. Two hundred thirty-eight patients underwent valve (subcoronary) replacement, 36 underwent aortic root replacement, and 2 underwent valve replacement using the root-inclusion technique. The early mortality was 5.4%, with 3.3% mortality for the subcoronary technique and 19.4% mortality for aortic root replacement. The mean gradient decreased significantly between discharge and the 3- to 6-month follow-up and stabilized thereafter. The effective orifice area increased significantly from discharge to 3 to 6 months’ follow-up. At 3 years, 84.4% of the patients had either no or trivial regurgitation. Conclusions. The Freestyle bioprosthesis has good clinical performance and good short-term hemodynamic performance. The majority of the regurgitation identified is not clinically significant.

Primary aortic valve replacement with allografts over twenty-five years: Valve-related and procedure-related determinants of outcome

Objectives: Allografts offer many advantages over prosthetic valves, but allograft durability varies considerably. Methods: From 1969 through 1993, 618 patients aged 15 to 84 years underwent their first aortic valve replacement with an aortic allograft. Concomitant surgery included aortic root tailoring (n = 58), replacement or tailoring of the ascending aorta (n = 56), and coronary artery bypass grafting (n = 87). Allograft implantation was done by means of a “freehand” subcoronary technique (n = 551) or total root replacement (n = 67). The allografts were antibiotic sterilized (n = 479), cryopreserved (n = 12), or viable (unprocessed, harvested from brain-dead multiorgan donors or heart transplant recipients, n = 127). Maximum follow-up was 27.1 years. Results: Thirty-day mortality was 5.0%, and crude survival was 67% and 35% at 10 and 20 years. Ten- and 20-year rates of freedom from complications were as follows: endocarditis, 93% and 89%; primary tissue failure, 62% and 18%; and redo aortic valve replacement, 81% and 35%. Multivariable Cox analyses identified several valve- and procedure-related determinants: rising allograft donor age and antibiotic-sterilized allograft for mortality; donor more than 10 years older than patient for endocarditis; rising donor age minus patient age, rising implantation time (from harvest to aortic valve replacement), and donor age more than 65 years for tissue failure; and rising donor age minus patient age, young patient age, rising implantation time, and subcoronary implantation preceded by aortic root tailoring for redo aortic valve replacement. Estimated 10- and 20-year rates of freedom from tissue failure for a 70-year-old patient with a viable valve from a 30-year-old donor and no other risk factors were 91% and 64%; the figures were 71% and 20% if the donor age was 65 years. The rates of freedom from tissue failure for a 30-year-old patient with a 30-year-old donor were 82% and 39%; the figures were 49% and 3% with a 65-year-old donor. Beneficial influences of a viable valve were largely covered by short harvest time (no delay for allografts from brain dead organ donors or heart transplant recipients) and short implantation time. Conclusions: Primary allograft aortic valve replacement can give acceptable results for up to 25 years. The late results can be improved by the use of a viable allograft, by matching patient and donor age, and by more liberal use of free root replacement with re-implantation of the coronary arteries rather than tailoring the root to accommodate a subcoronary implantation. (J Thorac Cardiovasc Surg 1999;117:77-91)

Stentless xenograft repair of excavating aortic root sepsis.

A variety of surgical techniques are used to manage a disintegrated aortic annulus in patients with endocarditis and excavating aortic root sepsis. Homograft root replacement is preferable in this setting but suitable homografts are restricted in availability and excision of the aortic root carries the risk of postoperative bleeding. As an alternative we used a stentless porcine xenograft root (Medtronic Freestyle valve) to manage this problem. Three male patients with active endocarditis presented with aortic root abscess and partial or complete aorto-left ventricular discontinuity. One had prosthetic valve endocarditis, and the abscess cavity entered the right atrium in another. The porcine aortic root was successfully implanted using the modified subcoronary technique providing a repair within the aortic root with proximal and distal suture lines that excluded the disintegrating tissues from the blood stream. All patients were treated with intravenous antibiotics for 6 weeks postoperatively and none suffered recurrent infection (follow-up > 6 months). The stentless porcine aortic root implanted within the human aorta provides an additional surgical option for excavating aortic root sepsis.

Hemodynamic performance of cryopreserved aortic homograft valves during midterm follow-up

Objectives. The aim of this prospective study of adult patients operated with a cryopreserved aortic homograft was to use serial echocardiographic data to evaluate the postoperative hemodynamic performance of these valves.Background. Only limited data on hemodynamic performance of aortic homografts at rest and during exercise are available. Controversy also exists regarding incidence and progression of aortic regurgitation (AR).Methods. Fifty-nine patients aged 39–86 years who received an aortic homograft (median size 21 mm) implanted with subcoronary technique were studied with serial Doppler-echocardiography (D-E). In 31 of these patients, D-E also was performed during supine exercise.Results. Overall survival was 100% during a median follow-up of 28 months (range 4–54). During follow-up AR grade II or more was detected in 25% of the patients with an increasing time-related risk of developing AR. Maximum and mean pressure differences at 7 months follow-up calculated with the short form of the Bernoulli equation were 11.4 (4.6) and 5.5 (2.1) mm Hg, respectively. During supine exercise that increased cardiac output 72%, maximum pressure difference increased from 11.9 (5.2) to 18.5 (9.5) mm Hg.Conclusions. The aortic homograft valve shows low pressure differences at rest and during exercise, but AR grade I or II is often seen during follow-up. As AR progresses with time we stress the importance of echocardiographic follow-up of patients with aortic homografts.

Homograft Aortic Valve Replacement: The Subcoronary and Cylindrical Techniques

Aortic valve replacement using the homograft valve has an important place in the cardiac surgical armamentarium. Despite this, the homograft valve is still not widely used, in part due to the perceived difficulty of the procedure compared with aortic valve replacement using prosthetic devices , less convenient availability of the homograft compared with that of prosthetic devices, and concerns regarding homograft valve failure. This section outlines the subcoronary technique (and its variations) and cylindrical technique for aortic valve replacement using the homograft aortic valve. Homograft aortic valves had a short investigational' and clinical2 application by insertion in the descending thoracic aorta. However, it was Ross3 who first performed a homograft aortic valve replacement in the orthotopic position using a single suture line technique based on the work of Duran and Gunning4 In the same year, working independently, Barrett-Boyes5 also described the subcoronary technique using a double