Impact of patient-prosthesis mismatch and aortic valve design on coronary flow reserve after aortic valve replacement.

OBJECTIVES: This prospective-randomized study investigated the effect of aortic valve design and patient-prosthesis mismatch (PPM) on coronary flow reserve (CFR) after mechanical or biological aortic valve replacement (AVR) in patients with aortic stenosis (AS). BACKGROUND: Coronary flow reserve may be an important parameter of long-term survival after AVR in patients with AS. Reduced CFR may contribute to more cardiovascular events and greater rates of mortality. METHODS: A total of 48 patients undergoing AVR underwent magnetic resonance imaging for the measurement of coronary flow preoperatively, 5 days postoperatively, and at 6-month follow-up with measurement of CFR. Patients scheduled for mechanical AVR were randomized to a tilting disc or bileaflet prosthesis (n = 12 in each group). For biological AVR, patients were scheduled to receive a stented (n = 12) or stentless (n = 12) valve. Patients also underwent echocardiography with measurement of transvalvular pressure gradients and left ventricular mass regression. RESULTS: Postoperatively, coronary flow increased significantly in all groups (p < 0.001). Only stentless valves demonstrated a normal CFR (3.4 +/- 0.3 vs. 2.3 +/- 0.1 for stented biological valves, 2.1 +/- 0.2 for tilting disc, and 2.2 +/- 0.3 for bileaflet mechanical valves). Patient-prosthesis mismatch with an indexed effective orifice area <0.85 cm2/m2 led to decreased rates of CFR in the tilting disc, stentless, and stented groups. Pressure gradients were 14 +/- 3 mm Hg for tilting disc, 12 +/- 4 mm Hg for bileaflet, 19 +/- 6 mm Hg for stented, and 10 +/- 4 mm Hg for stentless valves. CONCLUSIONS: Normalization of CFR after AVR in patients with AS was observed only for stentless valves. Coronary flow reserve might explain the excellent long-term results for stentless valves. (Impact of Patient-Prosthesis Mismatch on Coronary Flow Reserve; http://www.clinicaltrials.gov/ct/show/NCT00310947?order=1; NCT00310947).

Navigation-based needle puncture of a cadaver using a hybrid tracking navigational system.

PURPOSE: The purpose of this study was to determine the puncture accuracy of a navigational system, Medarpa, in a soft tissue environment using augmented overlay imaging. MATERIALS AND METHODS: Medarpa is an optical electromagnetic tracking system, which allows tracking of instruments, the radiologist's head position, and the transparent display. The display superimposes a computed tomography scan of a cadaver chest on a human cadaver in real time. In group A, needle puncture was performed using the Medarpa system. Three targets located inside the cadaver chest were selected. In group B, the same targets were used to perform standard computed tomography-guided puncture using a single-slice technique. A total of 42 punctures were performed in each group. Postpuncture computed tomography scans were made to verify needle tip positions. RESULTS: Mean deviation from targets was 8.42 mm +/- 1.78 mm for group A and 8.90 mm +/- 1.71 mm for group B. No significant difference was found between group A and B in any target (P > 0.05). No significant difference was found between the targets of the same group (P > 0.05). Procedural time for 42 punctures was 160 minutes in group A versus 289 minutes in group B (P < 0.05). CONCLUSION: Needle puncture in a soft tissue environment using the navigational system Medarpa can be reliably performed and matches the accuracy achieved by a computed tomography-guided puncture technique.

Stentless bioprostheses improve postoperative coronary flow more than stented prostheses after valve replacement for aortic stenosis.

OBJECTIVE: In some randomized studies, stentless aortic valves have demonstrated hemodynamic advantages in comparison with stented prostheses. The effect of more physiologic flow dynamics on coronary artery flow has not been investigated yet. This study compares coronary perfusion after aortic valve replacement with stented or stentless porcine bioprostheses in a prospective randomized study. METHODS: A total of 24 patients (73 +/- 6 years) referred for treatment of aortic stenosis were randomized to aortic valve replacement with stented (Medtronic Mosaic; (Medtronic Inc, Minneapolis, Minn) or stentless (Medtronic Freestyle; Medtronic Inc) prostheses. Coronary flow was measured by means of magnetic resonance imaging preoperatively, 5 days after the operation, and 6 months postoperatively, then with evaluation of coronary flow reserve. Echocardiography was performed to quantify transvalvular gradients and left ventricular mass regression. RESULTS: Coronary flow increased in both groups significantly (P < .001) after aortic valve replacement. This increase was higher in the stentless group compared with that seen in the stented group (343 +/- 137 vs 221 +/- 66 mL/min). Also, coronary flow reserve was higher for stentless valves (3.4 +/- 0.3 for stentless valves and 2.3 +/- 0.1 for stented valves). Mean pressure gradients for Freestyle valves were lower (10 +/- 4 and 8 +/- 3 mm Hg, respectively, vs 19 +/- 6 postoperatively and 15 +/- 4 mm Hg at follow-up for Mosaic valves, P < .05). Left ventricular mass regression was similar in both groups. CONCLUSIONS: Normalization of coronary artery flow after aortic valve replacement for aortic stenosis was more pronounced for stentless valves compared with stented valves. The fact that the stentless design also demonstrated a superior hemodynamic performance with lower pressure gradients might be explained by the design being closer to physiologic anatomy and thus the presence of lower turbulence levels in the sinuses of Valsalva.

Accuracy of biopsy needle navigation using the Medarpa system--computed tomography reality superimposed on the site of intervention.

The aim of this work was to determine the accuracy of a new navigational system, Medarpa, with a transparent display superimposing computed tomography (CT) reality on the site of intervention. Medarpa uses an optical and an electromagnetic tracking system which allows tracking of instruments, the radiologist and the transparent display. The display superimposes a CT view of a phantom chest on a phantom chest model, in real time. In group A, needle positioning was performed using the Medarpa system. Three targets (diameter 1.5 mm) located inside the phantom were punctured. In group B, the same targets were used to perform standard CT-guided puncturing using the single-slice technique. The same needles were used in both groups (15 G, 15 cm). A total of 42 punctures were performed in each group. Post puncture, CT scans were made to verify needle tip positions. The mean deviation from the needle tip to the targets was 6.65+/-1.61 mm for group A (range 3.54-9.51 mm) and 7.05+/-1.33 mm for group B (range 4.10-9.45 mm). No significant difference was found between group A and group B for any target (p>0.05). No significant difference was found between the targets of the same group (p>0.05). The accuracy in needle puncturing using the augmented reality system, Medarpa, matches the accuracy achieved by CT-guided puncturing technique.

Vascular guide wire navigation with a magnetic guidance system: experimental results in a phantom.

PURPOSE: To investigate the efficacy of a second-generation prototype magnetic guidance system in complex vessel phantoms versus conventional navigation in simulated interventional radiology procedures and to analyze procedure and fluoroscopy times. MATERIALS AND METHODS: The magnetic guidance system consists of two focused-field permanent magnets on each side of the body that create a 0.1-T navigation field and is integrated with a modified C-arm single-planar digital angiography system. Forty-nine navigations in a glass phantom and 80 navigations in a three-dimensional liver phantom were performed with a magnetically tipped floppy 0.014-inch guide wire and a conventional 0.014-inch microcatheter system. Rates of success and fluoroscopy and procedure times were quantified for both techniques. For the liver phantom experiment, the Mann-Whitney U test was used. For the glass phantom experiment, the Wilcoxon matched pair test was used with the Hodges-Lehmann estimator. RESULTS: In the glass phantom experiments, 42 of 49 turns were successfully performed with both methods. Procedure time to reach a target did not differ significantly between methods, while fluoroscopy time was significantly different when compared with that of the magnetic guidance system (P <.01). Navigation in the liver phantom was successful in 80 of 80 turns with the magnetic guidance system and in 76 of 80 turns with conventional navigation. With the support of the magnetic guidance system, procedure time and fluoroscopy time were significantly different from those with conventional navigation (P <.001). CONCLUSION: The magnetic guidance system allows the precise navigation of a magnetic guide wire in complex vessel phantoms with significantly shorter fluoroscopy and procedure times.

Combined modality treatment of oral and oropharyngeal cancer including neoadjuvant intraarterial cisplatin and radical surgery followed by concurrent radiation and chemotherapy with weekly docetaxel - three year results of a pilot study.

BACKGROUND: A new four-modality treatment of primary oral and oropharyngeal squamous cell carcinomas was evaluated with regard to feasibility, tolerance, and survival. PATIENTS AND METHODS: Seventy three operable patients (100%) with histologically proven untreated stage I to stage IV disease received at least one cycle of neoadjuvant intraarterial chemotherapy with 150 mg/m(2) cisplatin neutralized with sodium thiosulphate, followed by radical operation for the tumour with a simultaneous selective neck dissection (clinically negative neck), or modified radical neck dissection (nodal involvement), followed by adjuvant chemoradiation over 5 weeks (51.9 Gy, systemic docetaxel 25 mg/m(2), once every week). RESULTS: Ninety-six per cent of patients were operated on, 68% had postoperative radiation, 57% concomitant chemotherapy; 44% fulfilled the complete protocol. There have been 11 local or regional recurrences to date, three of which were treated by salvage surgery. Eighteen patients died, in nine of them death was tumour-related. Seventy five per cent lived after a median observation time of 33 months. Cumulative survival was 74% calculated for 4 years. CONCLUSION: The presented multimodality regimen proved feasible and showed better survival for the whole population and for all tumour stages when compared with the treatment-dependent prognosis index of the DOSAK (German-Austrian-Swiss Cooperative Group on tumours of the maxillofacial region).