Biomedical subjects

William H Ryan

Publications and source records attributed to William H Ryan.

7 recordsLinked to original sources

PubMed2006

Transapical aortic valve implantation: an animal feasibility study.

BACKGROUND: Percutaneous aortic valve implantation has recently been performed in nonsurgical patients with severe aortic stenosis. Retrograde valve delivery has been problematic because of the size of the delivery system and concomitant peripheral vascular disease. We investigated a minimally invasive approach through the left ventricular apex for antegrade placement of a device-deliverable valve. METHODS: Transapical aortic valve implantation was performed using a 23-mm equine valve mounted on a stainless steel stent in 24 swine (weight range, 35 to 45 kg). A limited or full sternotomy approach was used to access the apex of the heart. The crimped valve was introduced through a sheath in the left ventricular apex. Fluoroscopy and echocardiography were used for guidance. Deployments were performed on the beating heart either with ventricular unloading using femoral extracorporeal circulation or rapid ventricular pacing. RESULTS: All valves were successfully delivered at the selected target site with acceptable visualization of the noncalcified aortic annulus. Valve migration occurred during eight deployments (two distal and six retrograde) secondary to persistent cardiac output, unfavorable annular anatomy, and dislodgement by the delivery catheter. Exact positioning of the nonmigrated valves at the aortic annulus was examined by necropsy of all animals at the end of the procedures. Paravalvular leak was noted in 14 of 18 (77.8%) valves remaining in situ. CONCLUSIONS: The transapical approach was used for the successful antegrade placement of a stented valve, obviating the technical problems associated with a large delivery system transiting the peripheral vascular system. Stent design contributing to paravalvular leak remains problematic.

Animals↗

PubMed2006

The occurrence of postoperative pulmonary homograft stenosis in adult patients undergoing the Ross procedure.

BACKGROUND AND AIM OF THE STUDY: The Ross procedure employs an autologous pulmonary valve to replace the aortic valve, but requires pulmonary homograft replacement. Concerns regarding long-term homograft function may limit the adoption of this technique. Herein, the incidence of, and factors leading to, stenosis of the homograft were examined. METHODS: Data were collected from 131 patients (32 females, 99 males) who underwent a Ross procedure between July 1994 and December 2003. Complete follow up data were collected from 113 of 125 (90.4%) living patients. Donor valve information, including storage time, was supplied by the graft manufacturers. Data were analyzed using chi-square tests, t-test and logistic regression. RESULTS: The mean patient follow up was 703 +/- 574 days (median 599 days; range: 2 to 2,408 days). Echocardiographic stenosis had occurred in 14 patients (12.4%). Four patients (3.2%) required homograft replacement, and two required balloon valvuloplasty. There was no significant difference in graft vendor, recipient, donor age or blood type match between stenotic and non-stenotic recipients. Donor valve size was appropriate for the recipients, and greater than predicted by recipient body surface area (BSA). Donor valves that developed stenosis had a shorter storage time after processing (160 +/- 100 versus 249 +/- 223 days; p = 0.03). Male donor valves became stenotic in 9.9% (7/71) of male recipients, but in none of 20 females. Female donor valves became stenotic in 27.3% (3/11) of male recipients, and in 28.6% (2/7) females. Logistic regression showed donor gender to be a significant predictor for stenosis (p = 0.007; odds ratio 14.1 for female/male donors; 95% CI 2.1-96.4). CONCLUSION: Donor valves which developed stenosis had a shorter mean cryopreservation time than those that did not develop stenosis. In addition, female donor homografts appeared to develop stenosis at a greater rate, independent of patient age, graft size to BSA match, and blood type.

Adolescent↗

PubMed2005

Mitral valve surgery using the classical 'heartport' technique.

BACKGROUND AND AIM OF THE STUDY: Mitral surgery in selected patients using femoral cannulation, percutaneous retrograde cardioplegia and endoballoon aortic occlusion with a 4-5 cm thoracotomy is felt to carry a higher operative risk than sternotomy with conventional cannulation. Herein, the authors compared their experience of the first 117 'Heartport' (HP) patients with a computer-matched group of sternotomy approach surgical patients (SP) to assess operative risk and 30-day outcome. METHODS: Data were extracted from the authors' STS certified, audited database on 117 patients based on an intention to treat. Between December 1997 and December 2004, a total of 92 isolated mitral valve (MV) repair (HP-MVRpr) and 25 isolated MV replacement (HP-MVR) procedures was conducted using Heartport. The patients were matched 1:1 (by age +/-7 years, cerebrovascular disease, inotrope use, and ejection fraction +/- 5%) to a control SP group. Operative and 30-day outcomes were measured. RESULTS: No parameter showed any significant difference in 30-day outcome between the HP and SP groups, except for an increase in cross-clamp and perfusion times. Two patients in the HP-MVRpr group required conversion to sternotomy for repair of coronary sinus perforation, and one patient was repaired without conversion. Surgery in one HP-MVRpr patient was aborted due to limited aortic dissection, but successful repair was carried out later with a conventional approach. No patient required conversion to sternotomy for improved exposure of the operative site. CONCLUSION: Despite a longer cross-clamp time, 'classical' HP MV surgery can be performed with no increased risk compared to conventional MV surgery. Catheter and endoballoon complications were rare even in the early experience, and conversion to sternotomy was unusual and safely performed with this approach.

Adult↗

PubMed2004

Experience with various surgical options for the treatment of atrial fibrillation.

BACKGROUND: New alternatives exist using various energy sources and lesion lines for the surgical treatment of atrial fibrillation (AF). The efficacy of these options compared to the cut-and-sew maze III procedure is unknown. METHODS: From August 1996 to August 2003, 79 patients have undergone a procedure for AF, with 70 patients currently more than 3 months postsurgery. The patients (58 continuous, 12 paroxysmal) underwent a surgical procedure for AF, lone AF (12) and with concomitant procedures (58). Techniques included cut and sew (23), bipolar radiofrequency (RF) (28) and unipolar-RF (10), and cryothermy (9). Lesions included maze III (46), pulmonary vein isolation (16), and pulmonary vein isolation plus mitral annular connecting line only (8). RESULTS: Follow-up was complete in 58 (83%) of 70 patients at a mean time of 595 +/- 750 days (range, 24-2530 days). The operative mortality was 0% in lone AF patients and 7.1% (5/70) in patients undergoing concomitant procedures. Need for perioperative pacemaker was 22.9%. Overall, normal sinus rhythm (NSR) was restored in 82.7% of patients, with success in 83.3% (10/12) lone procedures and 82.6% (38/46) concomitant procedures ( P = NS); the rate of continuous AF was 85.1% (40/47) and SR with paroxysmal fibrillation was 72.7% (8/11) ( P = NS). Traditional maze was successful in 80.6% (29/36) patients, pulmonary vein isolation was successful 93.3% (14/15), and left-sided maze in 71.4% (5/7) ( P = NS). Cut and sew procedures were successful in 88.2% (15/17), RF-bipolar in 84.0% (21/25), RFunipolar in 77.8% (7/9), and cryothermy in 71.4% (5/7) ( P = NS). Energy source, lesion set, AF duration, and lone/concomitant procedure were the factors subjected to logistic regression analysis. No factors were predictive of achieving postoperative NSR. CONCLUSIONS: Our early experience with newer surgical techniques employing different energy sources and fewer incision lines suggests that the success rate may approach the results obtained with traditional cut-and-sew Cox-maze III procedures.

Atrial Fibrillation↗

PubMed2004

A prospective multicenter trial of bipolar radiofrequency ablation for atrial fibrillation: early results.

BACKGROUND: The Cox-Maze III remains the gold standard for the surgical treatment of atrial fibrillation. However, the "cut-and-sew" technique is time consuming and technically challenging. The pulmonary veins are the source of ectopy in the majority of patients with atrial fibrillation. The safety and efficacy of bipolar radiofrequency to electrically isolate the pulmonary veins was evaluated in a prospective multi-center trial. METHODS: Beginning in January 2002, 30 patients at three medical centers underwent pulmonary vein isolation using bipolar radiofrequency and were followed for 6 months. Twenty-four of the patients also underwent a modified Cox-Maze III. Electrical isolation of the pulmonary veins was confirmed with intraoperative pacing. Pulmonary vein patency was assessed by magnetic resonance imaging or three-dimensional computed tomography in 15 patients at 1 month. RESULTS: Mean age was 60.9 +/- 11.7 years. Nineteen patients had paroxysmal atrial fibrillation. All pulmonary veins were isolated in every patient. The left pulmonary veins underwent 3.0 +/- 1.4 applications for a total of 26.4 +/- 10.5 seconds. The right pulmonary veins underwent 2.8 +/- 1.1 applications for a total of 26.3 +/- 12.6 seconds. There was no operative mortality. At 1 month, imaging revealed no evidence of pulmonary vein stenosis. At 6 months, 96% of patients were in normal sinus rhythm. CONCLUSIONS: The use of bipolar radiofrequency for electrical isolation of pulmonary veins and to replace other Cox-Maze III incisions is safe and effective at controlling atrial fibrillation. This emerging technology may shorten and simplify the surgical management of atrial fibrillation.

Aged↗

PubMed2004

Port-access aortic valve surgery: a technique in evolution.

BACKGROUND: Innovative minimally invasive surgical techniques have been developed for treating many cardiac diseases. We reviewed our experience with port-access aortic valve replacement (PAVR) surgery. METHODS: We retrospectively reviewed the charts of patients with aortic valve disease who underwent surgical correction using the Heartport System and minithoracotomy (PAVR) from January 1998 to December 2002 (n = 58) and matched them 1:1 with a cohort of patients who underwent AVR with conventional sternotomy. RESULTS: No preoperative statistical differences existed between the groups, including age, sex, New York Heart Association class, and ejection fraction. Perioperatively, there was a statistically significant difference between the AVR and PAVR groups with regard to aortic cross-clamp time (74.0 +/- 22.9 minutes versus 92.7 +/- 20.4 minutes, P < .01). Average operative times improved in the PAVR group by almost 83 minutes from the first 10 patients to patients 21 to 31 (P = .05). PAVR patients also averaged shorter stays in the intensive care unit (ICU) (1.5 days less) and hospital (1.8 days less) and were extubated sooner (4.9 hours). Mortality (1/58, 1.7%) and morbidity (reoperation for bleeding, infection, and stroke) were similar for both groups. CONCLUSIONS: This minimally invasive approach to aortic valve surgery allows patients to be extubated earlier and promotes shorter stays in the ICU and hospital. These data suggest that the PA approach is an attractive alternative for patients requiring aortic valve surgery. There also appears to be a rapid surgeon learning curve.

Aged↗

PubMed2003

Safety and efficacy of minimally invasive atrial septal defect closure.

BACKGROUND: Atrial septal defects (ASDs) have been surgically closed with low mortality utilizing the conventional sternotomy approach (CSA). The technical ease of ASD closure has triggered interest in minimally invasive closure (MIC) to obviate the morbidity associated with sternotomy. Our study assesses the safety and efficacy of minimally invasive ASD closure. METHODS: Preoperative, intraoperative, and postoperative data were collected on 68 patients (39 CSA, 29 MIC) who underwent ASD closure from January 1997 to August 2002. Using univariate analysis of 17 preoperative risk factors there was no statistically significant difference between the two groups. RESULTS: MIC resulted in equivalent success rates in ASD closures, with similar morbidity, no mortality, and a significant difference in postoperative length of stay (3.93 +/- 1.6 days versus 5.36 +/- 2.51 days, p = 0.006). CONCLUSIONS: In experienced hands, MIC is an excellent alternative to CSA in ASD closure.

Adult↗