Rolf Salcher

Evolving Strategies for Treatment of Acute Aortic Dissection Type A

Objective—To assess the outcome of 3 different surgical approaches for treatment of acute aortic dissection type A (AADA). Methods and Results—Between October 1990 and October 2003, we operated on 295 patients (pts) for AADA. Follow-up was complete for 257 pts (87%). Supracommissural replacement (SCR) of the ascending aorta was applied to 145 pts, 64 pts received a composite replacement (comp), and 48 pts were treated with the aorta valve-sparing (AVS) reimplantation technique. Pts in SCR were older compared with AVS and comp (P=0.002), gender (overall 65% male, P=0.143) and presence of Marfan syndrome (overall 5%, P=0.109) were comparable. Cannulation of the aorta was performed more often in AVS (58%) than in comp (19%) or SCR (22%; P<0.001). Mean operation time, extracorporeal circulation time, and aortic cross-clamp time differ significantly between groups (P<0.001, respectively). Stay in the intensive care unit (P=0.12) and time of hospitalization (P=0.32) were comparable. Overall perioperative mortality was 24% and did not show significant differences between groups (AVS 10.4% versus comp 28% versus SCR 26%; P=0.053). Incidence of neurological complications was similar between groups (P=0.95). Mean time of follow-up was shorter for AVS (19±20 months) compared with comp (48±48 months) and SCR (46±45 months). Survival at 5 years was comparable with 89% for AVS, 85% for comp, and 80% for SCR (P=0.61). Two patients from AVS (4.1%) required reoperation for failure of the reconstructed valve. Pts in comp required less aortic reoperations than pts in SCR (comp 6.3% versus SCR 22%; P=0.005). Conclusions—In acute aortic dissection type A, the reimplantation technique leads to results comparable to established techniques. Complete removal of diseased tissue, low incidence of reoperation, and lack of anticoagulation may favor this approach in selected patients.

Decade of Aortic Valve Sparing Reimplantation Are We Pushing the Limits Too Far

Background—This single center study assesses the outcome of aortic valve sparing reimplantation (AVS) in 284 consecutive patients who were operated on for various indications during the last 11 years. Methods and Results—From July, 1993, to July, 2004, 284 patients underwent AVS. Mean age was 53±16 (range 8 to 84) years. Of the 284 patients, 184 were male (64.8%) and 54 (19%) experienced Marfan’s syndrome. Acute aortic dissection Stanford type A was present in 53 patients (19%) and a bicuspid aortic valve was present in 17 patients (6%). Concomitant arch replacement was necessary in 120 patients (42%). Additional procedures were performed in 66 patients (23.2%). Mean follow-up time was 41±32 (range 0 to 130) months. The 30-day mortality was 3.2% overall, 11.3% in emergency patients, and 1.3% in elective patients. Mean bypass time was 174±48 (range 90 to 440) minutes and aortic cross clamp time was 132±33 (range 64 to 283) minutes. In patients undergoing arch replacement, circulatory arrest was 25±17 (range 7 to 99) minutes. Rethoracotomy for bleeding was required in 4.6% of patients. During follow-up, there were 20 (7.3%) late deaths. Reoperation of the reconstructed valve was required in 15 patients (5.3%); underlying reasons were endocarditis (n=4) and aortic insufficiency (n=11) requiring aortic valve replacement. Average grade of aortic insufficiency increased significantly from 0.23±0.46 postoperatively to 0.34±0.59 at latest evaluation (P=0.026). Two patients experienced a transient ischemic attack early postoperatively; no further thromboembolic complications were noticed. The majority of patients (96%) presented with a favorable exercise tolerance at last contact. Conclusions—The aortic valve reimplantation technique leads to excellent clinical outcome in patients with various pathologies. Lack of anticoagulation and favorable durability should encourage the extension of indications for this technique.

Oval window membrane vibroplasty for direct acoustic cochlear stimulation: treating severe mixed hearing loss in challenging middle ears.

Objective To date, all the Vibrant Soundbridge (VSB) applications have managed to stimulate the inner ear indirectly. Our objective was to present a new VSB application for direct inner ear stimulation. Study Design Prospective cohort study. Settings Tertiary, referral center Patients Three patients with previous middle ear surgery and moderate-to-severe ipsilateral, mixed hearing loss. Interventions Oval window membrane vibroplasty (OWMV) for direct acoustic cochlear stimulation. A total ossicular replacement prosthesis (TORP) was attached to the floating mass transducer (FMT). Then, the stapes footplate was perforated, and the tip of the FMT-TORP assembly was advanced approximately 1 mm into the inner ear. A silicon ring was placed around the TORP’s tip to prevent it from slipping deeper into the inner ear. Main Outcome Measure Audiologic assessment involving pure-tone audiometry, aided and unaided free-field audiometry, Freiburg monosyllabic word test, and registration of any complications. Results OWMV resulted in an average functional hearing gain of 36.1 dB (range, 24.2–47.5 dB). Although the greatest amplification was observed in the higher frequencies, there also was a significant improvement in the lower frequencies. The surgery was not related to any difficulties; vertigo, inner ear trauma, or further complications did not occur. Conclusion We present a new method for direct acoustic cochlear stimulation using an active middle ear implant. The preliminary results show that OWMV is a promising and safe option for treating moderate and severe hearing loss, even in challenging cases with previous middle ear operations or fixed stapes footplate.

INHIBITION OF SMOOTH MUSCLE CELL MIGRATION AND NEOINTIMA FORMATION IN VEIN GRAFTS BY OVEREXPRESSION OF MATRIX METALLOPROTEINASE-3

OBJECTIVE Saphenous vein grafts suffer from neointima formation following bypass surgery. Matrix metalloproteinases (MMPs) play important roles in this process. We examined MMP-3 for its therapeutic potential to prevent smooth muscle cell migration and neointima formation in venous bypass grafts using adenovirus-mediated gene transfer. METHODS Human aortic smooth muscle cells (HASMC) were transduced with adenoviral vectors encoding ss-galactosidase (Ad.ssgal) [corrected] or human MMP-3 (Ad.hMMP-(3)), [corrected] and characterized for migration in the amniotic membrane stroma as an in vitro model of the vascular wall. Cholesterol-fed New Zealand white rabbits underwent jugular vein bypass grafting into carotid arteries. Before insertion, grafts were incubated ex vivo with either Ad.ssgal [corrected] or hMMP-3. Transgene expression was characterized by immunohistochemistry and in situ zymography. Grafts (n = 6) were explanted after 28 days and intimal hyperplasia was quantified. RESULTS Migration of HASMC was significantly reduced when transduced with Ad.hMMP-(3) [corrected] compared to controls (P < .001). Immunocytochemistry of Ad.hMMP-(3) [corrected] transduced venous grafts localized this protein to the intima. In situ-zymography showed increased MMP activity in the intima of Ad.hMMP-(3) [corrected] transfected grafts. Stenosis degree (P = .001), intima/media-ratio (P = .023) and lesion thickness (P = .003) were significantly reduced in grafts transduced with Ad.MMP-3 in comparison to controls. There was no difference inside control groups. CONCLUSION MMP-3 overexpression inhibits formation of intimal hyperplasia in arterialized vein grafts. Adenovirus mediated gene transfer of MMP-3 may be of clinical use to prevent vein graft stenosis following bypass surgery.

Round window stimulation with the floating mass transducer at constant pretension

OBJECTIVE Mechanical stimulation of the round window (RW) of the cochlea is successfully done with the Vibrant Soundbridge (Med-El), but clinical outcomes show a substantial degree of variability. One source of variability is variation in the static force applied by the stimulator to the round window (Maier et al., 2013). In this study we investigated other sources of variability by maintaining a constant pre-load testing the effect of a coupler device and the interposition of soft tissue between the stimulator and the RW. STUDY DESIGN Experimental. METHODS The stapes footplate displacement produced by stimulation of the round window was determined in fresh human temporal bones. The response to sound and actuator stimulation was measured with a Laser Doppler Velocimeter at the stapes footplate. The RW was stimulated by a Floating Mass Transducer (FMT) with/without (1) an additional RW coupler (supplied by the manufacturer), and (2) the interposition of TUTOPATCH between the stimulator and the RW, while maintaining a pre-load of ∼1.96 mN. RESULTS In 8 temporal bones with normal stapes footplate response to sound, we found an average 11.9 dB increase (500 Hz-2 kHz) under controlled conditions by using the coupler together with the interposition. The increase was statistically significant at 500 Hz (p < 0.01). Additionally, the coupler/interposition combination reduced the variability between experiments (FMT alone SD = 10.9 dB; FMT with TUTOPATCH & coupler: SD = 3.4 dB @ 500 Hz) and increased the repeatability. CONCLUSION At controlled static force an improved output level, inter-subject variability and repeatability were found by using a coupler/TUTOPATCH combination in RW stimulation with the FMT. The high variability found in clinical experience is not solely due to inter-subject variability, but to coupling conditions and can be optimized further.

The Impact of Electrode Array Length on Hearing Preservation in Cochlear Implantation.

Objective: The aim of the study was to determine the degree of hearing preservation (HP) and its relation to electrode array length after cochlear implantation using different thin flexible electrode arrays (TFEA). Study Design: Retrospective analysis. Intervention: One hundred twenty adult patients with preoperative residual hearing received a cochlear implant with a TFEA: 46 received a TFEA20, 34 a TFEA24, and 40 a TFEA28 mm. Main Outcome Measures: Pure-tone audiometry (125–1500 Hz) was performed preoperatively, at initial fitting, and at 3, 6, and 12 months postoperatively. Median hearing loss (HL) was determined for each of the three array groups. The pre- to postoperative pure-tone average difference was scaled into three groups (⩽15 dB, >15 to ⩽30 dB, >30 dB) for array group. Results: At initial fitting, median HL of 17.5 dB (TFEA20), 20 dB (TFEA24), and 24 dB (TFEA28) was observed. At 12 months, medial HL of 15 dB (TFEA20), 19.4 dB (TFEA24), and 32.5 dB (TFEA28) was observed. At initial fitting, a HL of ⩽15 dB was achieved in 45.6% TFEA20 subjects, 29.4% TFEA24 subjects, and 15.0% TFEA28 subjects; compared with 48.8% TFEA20 subjects, 50.0% TFEA24 subjects, and 15.8% TFEA28 subjects at 12 months. Conclusion: HP is possible in the majority of subjects who are implanted with a TFEA20, 24, or 28. Using shorter arrays led to greater HP and lower median HL.

The Codacs™ direct acoustic cochlear implant actuator: exploring alternative stimulation sites and their stimulation efficiency.

This work assesses the efficiency of the Codacs system actuator (Cochlear Ltd., Sydney Australia) in different inner ear stimulation modalities. Originally the actuator was intended for direct perilymph stimulation after stapedotomy using a piston prosthesis. A possible alternative application is the stimulation of middle ear structures or the round window (RW). Here the perilymph stimulation with a K-piston through a stapes footplate (SFP) fenestration (N = 10) as well as stimulation of the stapes head (SH) with a Bell prosthesis (N = 9), SFP stimulation with an Omega/Aerial prosthesis (N = 8) and reverse RW stimulation (N = 10) were performed in cadaveric human temporal bones (TBs). Codacs actuator output is expressed as equivalent sound pressure level (eq. SPL) using RW and SFP displacement responses, measured by Laser Doppler velocimetry as reference. The axial actuator coupling force in stimulation of stapes and RW was adjusted to ~ 5 mN. The Bell prosthesis and Omega/Aerial prosthesis stimulation generated similar mean eq. SPLs (Bell: 127.5–141.8 eq. dB SPL; Omega/Aerial: 123.6–143.9 eq. dB SPL), being significantly more efficient than K-piston perilymph stimulation (108.6–131.6 eq. dB SPL) and RW stimulation (108.3–128.2 eq. dB SPL). Our results demonstrate that SH, SFP and RW are adequate alternative stimulation sites for the Codacs actuator using coupling prostheses and an axial coupling force of ~ 5 mN. Based on the eq. SPLs, all investigated methods were adequate for in vivo hearing aid applications, provided that experimental conditions including constant coupling force will be implemented.

Treatment of middle ear ventilation disorders: sheep as animal model for stenting the human Eustachian tube--a cadaver study.

Eustachian tube disorders can lead to chronic otitis media with consecutive conductive hearing loss. To improve treatment and to develop new types of implants such as stents, an adequate experimental animal model is required. As the middle ear of sheep is known to be comparable to the human middle ear, the dimensions of the Eustachian tube in two strains of sheep were investigated. The Eustachian tube and middle ear of half heads of heathland and blackface sheep were filled with silicone rubber, blended with barium sulfate to induce X-ray visibility. Images were taken by digital volume tomography. The tubes were segmented, and a three-dimensional model of every Eustachian tube was generated. The lengths, diameters and shapes were determined. Additionally, the feasibility of endoscopic stent implantation and fixation was tested in cadaver experiments. The length of the tube between ostium pharyngeum and the isthmus and the diameters were comparable to published values for the human tube. The tube was easily accessible through the nose, and then stents could be implanted and fixed at the isthmus. The sheep appears to be a promising model for testing new stent treatments for middle ear ventilation disorders.

Differential Intracochlear Sound Pressure Measurements in Human Temporal Bones with an Off-the-Shelf Sensor

The standard method to determine the output level of acoustic and mechanical stimulation to the inner ear is measurement of vibration response of the stapes in human cadaveric temporal bones (TBs) by laser Doppler vibrometry. However, this method is reliable only if the intact ossicular chain is stimulated. For other stimulation modes an alternative method is needed. The differential intracochlear sound pressure between scala vestibuli (SV) and scala tympani (ST) is assumed to correlate with excitation. Using a custom-made pressure sensor it has been successfully measured and used to determine the output level of acoustic and mechanical stimulation. To make this method generally accessible, an off-the-shelf pressure sensor (Samba Preclin 420 LP, Samba Sensors) was tested here for intracochlear sound pressure measurements. During acoustic stimulation, intracochlear sound pressures were simultaneously measurable in SV and ST between 0.1 and 8 kHz with sufficient signal-to-noise ratios with this sensor. The pressure differences were comparable to results obtained with custom-made sensors. Our results demonstrated that the pressure sensor Samba Preclin 420 LP is usable for measurements of intracochlear sound pressures in SV and ST and for the determination of differential intracochlear sound pressures.

Comparison of two different titanium couplers for an active middle ear implant.

Objective To compare surgical methods, functional gain, and speech discrimination using two different coupling methods for an active middle ear implant. Of several couplers enabling placement of the active element at various locations, two function directly at a cochlear membrane, bypassing a missing or malformed ossicular chain. This study evaluates whether either of these methods is more beneficial. Study design Retrospective case review. Setting ENT surgical clinic. Patients Forty-seven German-speaking patients with moderate to severe mixed hearing loss. Interventions Records of patients implanted with either a round window (RW) or oval window (OW) coupler and active implant were examined. Preoperative and postoperative bone and air-conduction thresholds, auditory gain, and speech perception were compared. Main outcome measures Functional gain, Freiburger monosyllables in quiet. Results The range of hearing benefit shown by functional gain in patients implanted with the RW coupler (median) was between 22.5 dB (at 0.25 kHz) and 52.5 dB (2 and 3 kHz). In the OW group, improvement was similar, ranging from 21 dB (at 8 kHz) to 50 dB (1 and 2 kHz). Patients in both groups showed a similar improvement in speech recognition. Median preoperative unaided word recognition was 0% at 60 dB HL for both patient groups, improved postoperatively in both groups to median 85% correct at 65 dB HL and 95% at 80 dB HL. Conclusion Placement of an active middle ear implant using the RW and the OW coupler was found to be safe, although the surgical methods differ. Safety and efficacy of both couplers present no significant differences.