Echocardiography-guided Cardiac Implantable Electronic Device Implantation to Reduce Device Related Tricuspid Regurgitation: A Prospective Controlled Study

BACKGROUND

Endocardial leads of permanent pacemakers (PPM) and implantable defibrillators (ICD) across the tricuspid valve (TV) can lead to tricuspid regurgitation (TR) or can worsen existing TR with subsequent severe morbidity and mortality.

OBJECTIVES

To evaluate prospectively the efficacy of intraprocedural 2-dimentional-transthoracic echocardiography (2DTTE) in reducing/preventing lead-associated TR.

METHODS

We conducted a prospective randomized controlled study comparing echocardiographic results in patients undergoing de-novo PPM/ICD implantation with intraprocedural echo-guided right ventricular (RV) lead placement (Group 1, n=56) versus non-echo guided implantation (Group 2, n=55). Lead position was changed if TR grade was more than baseline in Group 1. Cohort patients underwent 2DTTE at baseline and 3 and/or 6 months after implantation. Excluded were patients with baseline TR > moderate or baseline ≥ moderate RV dysfunction.

RESULTS

The study comprised 111 patients (74.14 ± 11 years of age, 58.6% male, 19% ICD, 42% active leads). In 98 patients there was at least one follow-up echo. Two patients from Group 1 (3.6%) needed intraprocedural RV electrode repositioning. Four patients (3.5%, 2 from each group, all dual chamber PPM, 3 atrial fibrillation, 2 RV pacing > 40%, none with intraprocedural reposition) had TR deterioration during 6 months follow-up. One patient from Group 2 with baseline mild-moderate aortic regurgitation (AR) had worsening TR and AR within 3 months and underwent aortic valve replacement and TV repair.

CONCLUSIONS

The rate of mechanically induced lead-associated TR is low; thus, a routine intraprocedural 2DTTE does not have a significant role in reducing/preventing it.

Western-designed total knee implants mismatch Saudi patient knees. Anatomical bony measurements documented by computed tomography

Objectives:

To determine the anthropometric features of Saudi knees compared with knees of other ethnicities and reveal mismatches among different knee implant systems.

Methods:

All knee computed tomography images obtained between January 2016 and September 2016 for varying medical reasons in a tertiary care hospital in Southwestern Saudi Arabia were retrospectively evaluated. Patients aged <18 years, with trauma or soft tissue or bone tumors were excluded. Eleven parameters were measured for each knee joint.

Results:

We evaluated 100 knees of 50 Saudi patients (25 men, 25 women) aged 28-85 (mean, 57.3) years. No statistically significant differences were found in age and Sasaki angle measurements between male and female patients. All other parameters were significantly larger in male than female knees. Our measurements were close to those published for Chinese, Thai, and Korean patients; however, published measurements were larger for Caucasian and Indian knees than our measurements.

Conclusion:

The Saudi population has morphological features of knee bone anatomy that do not match with the widely available prostheses designed for Caucasian knees. As several studies of different ethnicities have documented considerable prosthesis mismatch; our study further indicates the need for new implant designs that take these variations into account.

Mild-moderate congenital hearing loss: secular trends in outcomes across four systems of detection

BACKGROUND

Universal newborn hearing screening (UNHS) targets moderate or greater hearing loss. However, UNHS also frequently detects children with mild loss that results in many receiving early treatment. The benefits of this approach are not yet established. We aimed to (i) compare language and psychosocial outcomes between four hearing loss detection systems for children aged 5-8 years with congenital mild-moderate hearing loss; (ii) determine whether age of detection predicts outcomes; and (iii) compare outcomes between children identified via well-established UNHS and the general population.

METHODS

Linear regression adjusted for potential confounding factors was used throughout. Via a quasi-experimental design, language and psychosocial outcomes were compared across four population-based Australian systems of hearing loss detection: opportunistic detection, born 1991-1993, n = 50; universal risk factor referral, born 2003-2005, n = 34; newly established UNHS, born 2003-2005, n = 41; and well-established UNHS, born 2007-2010, n = 21. In pooled analyses, we examined whether age of detection predicted outcomes. Outcomes were similarly compared between the current well-established UNHS system and typically developing children in the Early Language in Victoria Study, born 2003, n = 1217.

RESULTS

Age at diagnosis and hearing aid fitting fell steadily across the four systems. For moderate losses, mean expressive language (P for trend .05) and receptive vocabulary (P for trend .06) improved across the four systems, but benefit was not obvious for mild losses. In pooled analyses, diagnosis before age six months predicted better language outcomes for moderate losses. Children with mild-moderate losses exposed to well-established UNHS continue to experience expressive language scores well below children in the general population (adjusted mean difference -8.9 points, 95% CI -14.7 to -3.1).

CONCLUSIONS

Treatment arising from UNHS appears to be clearly benefitting children with moderate hearing losses. However, rigorous trials are needed to quantify benefits, versus costs and potential harms, of early aiding of children with mild losses.

Effectiveness of controlled telescoping system for lateral hip pain caused by sliding of blade following intramedullary nailing of trochanteric fracture

INTRODUCTION

The purpose of this study was to demonstrate the effectiveness of controlled telescoping system for lateral hip pain caused by sliding of the blade following intramedullary nailing of trochanteric fractures.

MATERIALS AND METHODS

A retrospective cohort study was performed to compare the controlled telescoping system (Compression Hip Nail; CHN) with the conventional sliding system (Proximal Femoral Nail Antirotation; PFNA) for trochanteric fractures. 74 cases in the PFNA group and 77 cases in the CHN group were included from two university hospitals in this study. All patients had a minimum of 12-month follow up period. Lateral hip pain was evaluated and operation time and blood loss during the surgery were measured. The fracture classification was evaluated. The quality of postoperative reduction and other complications after surgery were also evaluated and tip-apex distance (TAD), telescoping and lateral protrusion of the blade and lag screw were measured.

RESULTS

The mean age was 78.5 years in the PFNA group and 74.7 years in the CHN group (p=0.25). The mean telescoping was 19.2mm in the PFNA group and 10.7mm in the CHN group (p<0.001). The mean length of lateral protrusion was 10.5mm in the PFNA group and 2.5mm in the CHN group (p<0.001). Twenty-eight patients in the PFNA group complained of lateral hip pain, whereas 12 patients in the CHN group did (p=0.002). These four variables showed statistically significant differences between the PFNA and CHN groups (p<0.05). The length of lateral protrusion was the only variable significantly related to lateral hip pain through multivariate logistic regression analysis (p=0.045).

CONCLUSIONS

The degree of lateral protrusion was mainly related to lateral hip pain. Therefore, controlled telescoping would help to decrease lateral hip pain by decreasing the lateral protrusion beyond the lateral femoral cortex.

The Difference Between Success and Failure: Subintimal Stenting Around an Occluded Stent for Treatment of a Chronic Total Occlusion Due to In-Stent Restenosis

We present a case where conventional wire and equipment passage through the proximal cap of a chronic total occlusion due to in-stent restenosis was not possible. The lesion was then safely and successfully treated by deliberate passage into the subintimal space outside the previous stent with subsequent subintimal dissection and reentry into the true lumen beyond the occlusion. We then stented around the occluded stent, effectively crushing the previous stent in the true lumen and restoring flow by stenting open the new subintimal lumen. Follow-up angiography and optical coherence tomography at 6 months demonstrated good medium-term results.

Feasibility of sheathless transfemoral aortic valve implantation in patients with small access vessel diameters

OBJECTIVES

We intended to show feasibility of sheathless transfemoral aortic valve implantation in patients with small access vessel diameters.

BACKGROUND

Transcatheter aortic valve implantation (TAVI) has emerged as a valid treatment option in patients with aortic valve stenosis who are poor candidates for surgical aortic valve replacement. Few patients, who cannot undergo transfemoral or transsubclavian aortic valve implantation due to small access vessel diameters, are not suitable for transapical or direct aortic valve implantation, either.

METHODS

In more than 700 transcatheter aortic valve implantations since 2008 we identified 17 patients who had to be excluded from transfemoral valve implantation due to vessel diameters <6 mm and who were no candidates for transapical or direct aortic implantation. We performed CoreValve™ implantations in these patients without the required 18F sheath to cross the vessels despite their small size (4.6-5.9 mm).

RESULTS

Sixteen sheathless implantations were successful. In all 17 patients, bleeding during the procedure due to the smaller delivery catheter was minimal. Sixteen patients had a successful access site closure at the end of the procedure.

CONCLUSIONS

Sheathless implantation of a self-expanding aortic valve can be safely considered in selected patients with access vessel diameters below 6 mm, if transapical or direct aortic implantation is not suitable.

[Practical tips and tricks in fitting soft contact lenses]

This review is intended to give supportive information for beginners in contact lens fitting who are interested in providing a quality-related service to customers and patients. In Germany the proportion of contact lens wearers is significantly lower than in most other countries; therefore, there is a potentially fast growing market. The aim of this paper is to provide comprehensive guidelines for practitioners to develop and improve contact lens fitting practice and minimize unnecessary or preventable complications. The fundamental requirement for starting in contact lens fitting is to have correct education in the field and for the practice to be appropriately equipped. The key to providing a safe a reliable contact lens fitting practice is to continually update knowledge in the field and to maintain the practice to the highest professional standards.

Patient-prosthesis mismatch has no influence on in-hospital mortality after aortic valve replacement

OBJECTIVE

To analyze the relationship between prosthetic aortic valve orifice and body surface area (Effective Orifice Area Index, EOAI) and in-hospital mortality after aortic valve replacement.

MATERIAL AND METHOD

A prospective study was conducted between October 2007 to September 2010, 536 patients underwent isolated aortic valve replacement (AVR) was recorded on preoperative, operative and postoperative data. Patient Prosthesis Mismatch (PPM) was classified by Effective Orifice Area Indexed (EOAI) by prosthetic valve area divided by body surface area as mild or no significance if the EOAI is greater than 0.85 cm2/m2, moderate if between 0.65 cm2/m2 and 0.85 cm2/m2, and severe if less than 0.65 cm2/m2. Statistical differences were analyzed by Chi-square and student t-test with p-value less than 0.05 considered significant.

RESULTS

There were 304 men, mean age was 60.98 years, mean valve orifice area 1.69 cm2, body surface area 1.60 m2, cross clamp time 1.13 hrs., bypass time 1.67 hrs. Mechanical valves were used in 274 patients (51.2%) and Bioprosthesis were used in 181 patients (48.8%). PPM was found in 33.7%, 6.7% was severe PPM, 27% was moderate PPM and 66.3% has no significant PPM Over all in-hospital mortality was 1.5%. There was no significant difference in hospital mortality between no PPM group, moderate PPM and severe PPM group (1.4% vs. 1.4% vs. 5.4%, p-value = 0.86).

CONCLUSION

In a large aortic valve surgery population, moderate and severe patient prosthesis mismatch occurred in 35.6% of patients but had no influence on in-hospital mortality.

The effect of implant malalignment on joint loading in total elbow arthroplasty: an in vitro study

HYPOTHESIS

Aseptic loosening is one of the leading causes of failure in total elbow arthroplasty. Incorrect implant positioning and alignment in other joints such as the knee have been found to lead to excessive loading and wear. Although similar alignment difficulties exist in the elbow, the effect of implant malalignment on wear-inducing loads is not yet known. This in vitro study determined the effect of anterior malpositioning and varus-valgus and internal-external malrotations on humeral stem loading in total elbow arthroplasty.

METHODS AND MATERIALS

Computer-navigated linked elbow arthroplasty was conducted in 8 cadaveric elbows. A modular, instrumented humeral component was used to measure loading during simulated elbow motion while the position of the ulna relative to the humerus was recorded.

RESULTS

Loading increased for all malaligned implant positions tested (P < .05). During simulation of implant malpositioning, combinations of internal-external and varus-valgus malrotations that tended to preserve the line of action of the elbow flexors had lower loads than combinations that did not.

DISCUSSION

This in vitro study showed that loading does increase after humeral component malalignment; however, further studies are required to determine the long-term effects on polyethylene wear and component loosening.

Clinical predictors of prosthesis-patient mismatch after aortic valve replacement for aortic stenosis

OBJECTIVE

We sought to ascertain predictors of Patient Prosthesis Mismatch, an independent predictor of mortality, in patients with aortic stenosis using bioprosthetic valves.

METHOD

We analyzed 2,107 sequential surgeries. Patient Prosthesis Mismatch was calculated using the effective orifice area of the prosthesis divided by the patient's body surface area. We defined nonsignificant, moderate, and severe Patient Prosthesis Mismatch as effective orifice area indexes of .0.85 cm(2)/m, 0.85-0.66 cm(2)/m(2), and <0.65 cm(2)/m(2), respectively.

RESULTS

A total of 311 bioprosthetic patients were identified. The incidence of nonsignificant, moderate, and severe Patient Prosthesis Mismatch was 41%, 42, and 16%, respectively. Severe Patient Prosthesis Mismatch was significantly more prevalent in females (82%). In severe Patient Prosthesis Mismatch, the perfusion and the crossclamp times were considerably lower when compared with nonsignificant Patient Prosthesis Mismatch and moderate Patient Prosthesis Mismatch. Patients with severe Patient Prosthesis Mismatch had a significantly higher likelihood of spending time in the intensive care unit and a significantly longer length of stay in the hospital. Body surface area was not different in severe Patient Prosthesis Mismatch when compared with nonsignificant Patient Prosthesis Mismatch. In-hospital mortality in patients with nonsignificant, moderate, and severe Patient Prosthesis Mismatch was 2.3%, 6.1%, and 8%, respectively. Minimally invasive surgery was significantly associated with moderate Patient Prosthesis Mismatch in 49% of the patients, but not with severe Patient Prosthesis Mismatch.

CONCLUSION

Severe Patient Prosthesis Mismatch is more common in females, but not in those with minimal available body surface area. Though operative times were shorter in these patients, intensive care unit and hospital lengths of stay were longer. Surgeons and cardiologists should be cognizant of these clinical predictors and complications prior to valve surgery.

Manufacturer-provided effective orifice area index charts and the prevention of prosthesis-patient mismatch

Prosthesis-patient mismatch (PPM) occurs when an implanted prosthesis is too small relative to the patient's body surface area (BSA). However, mismatch can often be prevented by indexing the expected effective orifice area (EOA) of a prosthesis to the patient's BSA and then selecting the largest implantable prosthesis to avoid mismatch. Previously, prosthesis manufacturers have attempted to simplify this process by providing charts that include the expected EOA for their prosthesis, already indexed into an array of BSA values. One caveat with these charts is that the expected EOA data must truly be reliable, or the charts will misguide the implanting surgeon. Manufacturer-provided charts could be improved by standardizing the EOA data, with one potential source being the hemodynamic data submitted to the United States Food and Drug Administration. This review discusses PPM, manufacturer-provided EOA charts, and the regulation of EOA data.

[Impact of prosthesis-patient mismatch on the quality of life of elderly patients after aortic valve replacement]

OBJECTIVE

To evaluate the long-term changes in the quality of life (QOL) scores in elderly patients after aortic valve replacement, and assess the impact of prosthesis-patient mismatch on the QQL of the patients.

METHODS

A prospective cohort study was conducted involving 100 consecutive elderly patients above 70 years of age, who underwent isolated aortic valve or simultaneous aortic valve-coronary artery bypass graft (CABG) procedures between August 10, 1995 and August 19, 1998. Patient-prosthesis mismatch (PPM) was defined as a prosthetic aortic valve EOAI of 0.85 cm2/m2 or less. The clinical follow-up examinations were carried out at 4 weeks and 6 months after the operation, and then annually afterwards. Cumulative and comparative analyses of the long-term outcomes and gradient pressure of the prosthetic valve were performed. The QOL of the patients was evaluated using the Short Form 36-Item Health Survey (SF-36) questionnaire.

RESULTS

The mean age of the patients at prosthesis implantation was 74.7-/+5.7 years (range 70-87 years). The patients were followed up for a mean of 7.3-/+4.5 years. The thirty-day mortality was 6.3% in the mismatch group, and 3.3% in the matching group. The freedom from death showed no significant difference between the two groups at the first, third and fifth years after the prosthetic implantation, but differed significantly at the seventh year. The echocardiographic data showed significant differences in the mean gradient pressure between the two groups at the first and fifth years postoperatively. At most of the time points for follow-up examination, the general health and energy/vitality of the patients all improved from the preoperative levels, but no significant improvement was found at the third, fifth, and seventh years in the role emotional, social role, or general mental health; at the first postoperative year, however, the role emotional, social role, and particularly mental health, presented with significant improvements in comparison with the preoperative levels. No obvious difference in the QOL was noted between the two groups at the time points of observation.

CONCLUSIONS

Aortic vale replacement improves the QOL of the elderly patients, but the degree of improvements do not seem to be influenced by PPM. The interpretation of the impact of PPM on the clinic outcome of the patients still remains controversial.

Three-dimensional finite element analysis of the effect of incomplete seating of cemented fixed dental prostheses

This study investigated the stress distribution patterns of two finite element models of a stylized fixed dental prosthesis-cement-abutment tooth system, one with the prosthesis completely seated and the other manipulated to be incompletely seated. Maximum equivalent von Mises stress varied according to direction and location of load, with vertical loading of the pontic of the completely-seated FDP (2.9 MPa) and oblique loading of the premolar of the incompletely-seated FDP (80.8 MPa) producing the least and the highest values, respectively. Total deformation of the restored system showed variations, although different cements had minimal effect on stress and on deformation. Under the conditions studied, a fixed dental prosthesis that had not been verified as fully seated on its abutments prior to cementation, could, with repeated loading cycles, be predicted to suffer a greater risk of fatigue, and thus clinical failure.

Does patient-prosthesis mismatch influence the results of combined aortic valve replacement and coronary bypass grafting?

BACKGROUND

Combined aortic valve replacement and coronary revascularisation is becoming more frequent. Patient-prosthesis mismatch (PPM) as an additional risk factor may potentially affect the early and late outcome.

AIM

To evaluate the impact of PPM on early and mid-term clinical results including quality of life in patients undergoing combined surgical treatment of coronary artery disease and aortic valve defects.

METHODS

Medical records of 309 consecutive patients referred for combined surgery were reviewed. Patients were divided into three groups according to the presence of moderate or severe PPM (defined by aortic valve effective orifice area index in the range 0.85-0.65 cm2/m2 and smaller than 0.65 cm2/m2, respectively) or absence of PPM. The demographic and perioperative data, and early and late survival, as well as quality of life (SF-36) were analysed.

RESULTS

The presence of severe PPM was found in 51 (16.5%) patients, whereas moderate PPM--in 153 (49.5%) patients. Patients from both PPM groups were significantly older than those without PPM. Subjects with severe PPM had higher weight and body mass index. They frequently had dyslipidaemia and both PPM groups received a biological valve more often than patients without PPM (94.1 and 77.1 vs. 19.1%, p<0.0001). There was no significant difference between all groups regarding early or late mortality. Advanced age, renal insufficiency and arrhythmia were predictors of early death. Late survival was determined only by number of postoperative complications in a Cox regression model. There was no difference in any components of the SF-36 survey between all groups.

CONCLUSIONS

PPM is a frequent phenomenon in older patients requiring aortic valve replacement and revascularisation. Severe PPM occurs rarely, predominantly in obese patients. However, its presence does not affect early and late survival or quality of life.

Exzessives Tränen bei Gleitsichtglasfehlzentrierung

BACKGROUND

The eye and the progressive lenses in eyeglasses form a three-dimensional optical system, which must be well matched.

PATIENT

A 71-year-old man complained about a new and unusual tearing and scratching sensation in his eyes. The work-up revealed subnormal values of the Schirmer test, from the eye refraction of different eyeglass powers and strongly decentred progressive lenses in his, just a few-months-old, eyeglasses.

THERAPY AND OUTCOME

A lubricating therapy remained without success. However, the use of new and correct eyeglasses eliminated the symptoms.

CONCLUSION

Tearing and the sensation of scratching in the eyes in this case are symptoms of an eyeglasses-induced asthenopia. Consequently, it may pay to control the eyeglasses and the centration of progressive lenses in cases with unclear, unspecific eye symptoms even without dissatisfaction with eyeglasses.

[Aortic valve replacement with a small valve prosthesis: a review of clinical and echocardiographic studies for impact of prosthesis-patient mismatch]

Aortic valve replacement (AVR) has become standard therapy for treating diseases of the aortic valve. However, the selection of a prosthetic valve is considered to be an important factor determining postoperative recovery of cardiac function and quality of life, because the use of small valve prostheses may cause residual obstruction to left ventricular outflow. The situation in which "the effective prosthetic valve area, after insertion into the patient, is less than that of a normal human valve," has been described as "prosthesis-patient mismatch (PPM)." The most commonly used measure of PPM is the valve effective orifice area indexed to body surface area (EOAI), and PPM is generally defined as EOAI < or =0.85cm(2)/m(2). In this paper, we review clinical and echocardiographic studies of small valve prostheses in the aortic position to investigate the clinical impacts of PPM on short- and long-term outcomes after AVR. Some studies have shown decreased symptom resolution, poor regression of left ventricular mass, or decreased survival with an EOAI < or =0.85cm(2)/m(2), while others have observed no adverse effects of PPM on short- and long-term results of AVR. Therefore, even in Western countries, in studies involving large numbers of patients, conclusions drawn concerning the impact of PPM differ greatly among reports. In conclusion, it is desirable to examine in detail, in many patients, whether the use of prosthetic valves with EOAI < or =0.85cm(2)/m(2) is also a risk factor for poor prognosis in Japanese patients, whose body size is in general smaller than that of Western patients.

Accidental sizing of patent foramen ovale during atrial septal defect sizing for device

A 21 year old lady with a 22 mm secundum atrial septal defect with adequate rims, and thin septum at the region of the fossa ovalis, but no additional atrial septal defect by transthoracic and transoesophageal echocardiogram was taken up for ASD sizing with a view to device closure. Initially, the ASD was sized to only 8 mm. However, the distal balloon was not fully opened out, and seemed to be conical with restricted opening. Inadvertent passage of sizing balloon through a patent foramen ovale (PFO) was immediately confirmed by transthoracic echocardiogram. The ASD was then recrossed and sized to 24 mm with normal opening out of the distal balloon. This was confirmed by transthoracic echocardiogram. A 28 mm ASD device was deployed across the ASD under transthoracic echocardiographic guidance with no residual flow.

Patient prosthesis mismatch affects short- and long-term outcomes after aortic valve replacement☆

OBJECTIVE

The aim of this study was to evaluate the impact of patient prosthesis mismatch (PPM) and additional risk factors on outcome after aortic valve replacement (AVR).

METHODS

Four thousand one hundred and thirty-one patients who were operated between May 1996 and April 2004 were evaluated. One thousand eight hundred and fifty-six patients received bileaflet mechanical AVR and 2275 stented xenograft AVR. PPM was defined as severe if manufacturers effective orifice area (EOA) divided by body surface area (BSA) was <0.65 cm(2)/m(2) and as moderate in the range of 0.65-0.85 cm(2)/m(2). PPM, age, gender, EOA index, emergency indication for surgery (within 24h), EuroSCORE as well as requirement for additional procedures were tested. Univariate (Fisher's exact test) and multivariate logistic regression analysis as well as survival analysis (Kaplan-Meier) were performed.

RESULTS

Severe PPM was present in 97 (2.4%) and moderate PPM in 1103 (26.7%) patients. PPM occurs more frequently with xenograft AVR. In-hospital mortality was 5.2% for severe, 10.6% for moderate and 6.9% with no PPM (p=0.018, OR 1.4). Moderate PPM was independently predictive for short- and long-term mortality. Further analysis revealed patient age >70 years (n=1589, p=0.002, OR 1.85), emergency indication (n=374, p<0.001, OR 4.4), EuroSCORE >10 (n=494, p<0.001, OR 4.7) and additional cardiac procedures (n=2049, p<0.001, OR 2.0) as predictors for adverse outcome after AVR.

CONCLUSION

Severe PPM is rare; moderate PPM is present in a quarter of patients. PPM has a significant impact on short- and long-term mortality after AVR.

[Silicone as a foreign body in the middle ear: a rare complication after taking an impression of the auditory canal]

For the individual design of ear moulds, silicone is generally used for taking the impression of the external meatus and the cavum conchae. Complications are rare with only a few accounts in the literature. We report on three cases of accidental displacement of silicone into the middle ear cavity during impression taking. Clinical symptoms and detection of silicone as a rare middle ear foreign body are presented and discussed.

Acetabular Cup Geometry and Bone-Implant Interference have More Influence on Initial Periprosthetic Joint Space than Joint Loading and Surgical Cup Insertion

Environmental variations in patient-dependent and surgical factors were modeled using robust optimization with a finite element acetabular cup-pelvis model. A previously developed statistical optimization scheme was used to: (1) determine the cup geometry and the optimal cup-bone interference that maximized bone-implant contact areas and minimized changes in the gap volume between the implant and bone surface during gait loading and unloading; and (2) determine the relative contributions of design, patient-dependent, and surgical factors to variations in bone-implant contact areas and a change in gap volume. The statistical analyses indicated that the design variables, namely the equatorial diameter and eccentricity, explained most of the variations in the performance measures. Further, the hemispherical designs performed better than the nonhemispherical designs. The 58mm hemispherical cup, with 2mm diametral interferences, minimized the change in gap volume and attained 82% and 81% of the maximum predicted total and rim contact areas, respectively. The equatorial diameter and eccentricity, not the patient-dependent and surgical factors, explained most of the variations in the performance measures. Perfect surface apposition was not attained with any of the cup designs.

Difficulties in the fixation of prostheses for voice rehabilitation after laryngectomy

In most patients with advanced or recurrent laryngeal or hypopharyngeal cancer, total laryngectomy is indicated. This means the loss of three main functions: phonation; respiration; and the prevention of aspiration during deglutition. Laryngectomy patients have various options to restore phonation: an oesophageal voice; an electrolaryngeal voice; or a tracheo-oesophageal voice. In the last case a silicone rubber shunt valve is placed in the tracheo-oesophageal wall and phonation is generated when exhaled air is forced through the oesophagus and neopharynx. This method is widely applied in Western Europe. In this paper we review the literature on fixation problems with shunt valves, tracheostoma valves and heat and moisture exchange (HME) filters. Tracheo-oesophageal speech without a valve is not considered. Despite 22 years of experience with the implantation of tracheo-esophageal shunt valves and many improvements in the design, problems still remain, such as biofilm formation with subsequent leakage through the valve, the need for frequent and inconvenient replacements, fistula enlargement leading to leakage around the device and reduced fixation, and infections. The high cost of shunt valves is a drawback to their use worldwide. To enable hands-free speech, different types of tracheostoma valve have been developed. These valves are fixed to the skin or to the tracheostoma by means of an intra-tracheal device. An HME filter is used to protect the airway and maintain physiological balance. Such devices are only suitable for a selected group of patients as fixation to the skin or trachea can be a major problem. Speaking and coughing cause pressure increases, which often result in mucous leakage and disconnection of the valve and/or HME filter. Recommendations are made for future improvements in fixation techniques.

A dangerous place to live: from the fog of war to the slime of technology

This article addresses the need for constant vigilance against clever and adaptive enemies, specifically the battle against infections. Medical devices are susceptible to infection and risk management needs to be considered in the context of the underlying science and common sense.

Automated, patient-interactive, spinal cord stimulator adjustment: a randomized controlled trial

OBJECTIVE

Programmable, multicontact, implanted stimulation devices represent an important advance in spinal cord stimulation for the management of pain. They facilitate the technical goal of covering areas of pain by stimulation-evoked paresthesiae. Adjustment after implantation requires major investments of time and effort, however, if the capabilities of these devices are to be used to full advantage. The objective of maximizing coverage should be met while using practitioners' time efficiently.

METHODS

We have developed a patient-interactive, computerized system designed for greater ease and safety of operation, compared with the standard external devices used to control and adjust implanted pulse generators. The system automatically and rapidly presents to the patient the contact combinations and pulse parameters specified by the practitioner. The patient adjusts the amplitude of stimulation and then records drawings of stimulation paresthesiae (for comparison with pain drawings), followed by visual analog scale ratings for each setting. Test results are analyzed and sorted to determine the optimal settings. We compared the automated, patient-interactive system with traditional, practitioner-operated, manual programming methods in a randomized controlled trial at two study centers, with 44 patients.

RESULTS

The automated, patient-interactive system yielded significantly (P < 0.0001) better technical results than did traditional manual methods, in achieving coverage of pain by stimulation paresthesiae (mean 100-point visual analog scale ratings of 70 and 46, respectively). The visual analog scale ratings were higher for automated testing for 38 patients, higher for manual testing for 0 patients, and equal (tied) for 6 patients. Multivariate analysis demonstrated that the advantage of automated testing occurred independently of practitioner experience; the advantage was significantly greater, however, for experienced patients. The rate of testing (number of settings tested per unit time) was significantly (P < 0.0001) greater for the automated system, in comparison with the rate with a human operator using traditional, manual, programming methods (mean of 0.73 settings/min versus 0.49 settings/min). The automated system also identified settings with improved estimated battery life (and corresponding anticipated cost savings). No complications were observed with automated testing; one complication (transient discomfort attributable to excessive stimulation) occurred with manual testing.

CONCLUSION

Automated, patient-interactive adjustment of implanted spinal cord stimulators is significantly more effective and more efficient than traditional manual methods of adjustment. It offers not only improved clinical efficacy but also potential cost savings in extending implanted battery life. It has the additional potential advantages of standardization, quality control, and record keeping, to facilitate clinical research and patient care. It should enhance the clinical application of spinal cord stimulation for the treatment of chronic intractable pain.

Rehabilitation considerations of prosthetic fittings for Kaposi's sarcoma amputees

PURPOSE

We report on cutaneous limb manifestations of Kaposi's sarcoma and the secondary infection of these lesions that necessitated five lower-limb amputations.

METHOD

The cases are briefly described and prosthetic adaptations in respect to pressure, traction and sweating on the skin are considered.

RESULTS

All four patients ambulated initially; one lady died, the double amputee stopped walking owing to the excessive physical demand, and two patients ambulate freely.

CONCLUSION

Special considerations to the cutaneous/prosthesis interface are necessary in order to provide these patients with optimal ambulatory ability.

Impact of prosthesis-patient mismatch on hemodynamic and symptomatic status, morbidity and mortality after aortic valve replacement with a bioprosthetic heart valve

BACKGROUND AND AIMS OF THE STUDY

Previous studies have shown that the effective orifice area of an aortic prosthetic valve may be too small in relation to the patient's body surface area, resulting in abnormally high gradients. The consequences of this condition, termed prosthesis-patient mismatch, have not been fully studied. The study objective was to determine if the condition has a detrimental effect on symptomatic and hemodynamic status, morbidity and mortality of patients undergoing aortic valve replacement.

METHODS

A cohort of 392 patients was prospectively followed for up to seven years after implantation of a Medtronic Intact bioprosthesis. Doppler echocardiography was performed annually in 72 patients. Based on previous studies, presence of mismatch was defined as an indexed valve area < or = 0.85 cm2/m2.

RESULTS

Mismatch was associated with less postoperative improvement of NYHA functional class (p < 0.009) independently of other predictors, such as age and preoperative functional class, but had no significant impact on patient survival (mismatch: 75 +/- 4%, no mismatch: 79 +/- 3%; p = 0.59) and valve-related morbidity up to seven years. Cardiac index was similar in patients with and without mismatch up to three years after operation but decreased significantly thereafter only in patients with mismatch (-0.54 +/- 0.32 versus -0.17 +/- 0.49 l/min/m2; p = 0.04). Likewise, the mean transprosthetic gradient, which was higher at one year after operation in patients with mismatch (22 +/- 8 versus 15 +/- 7 mmHg), increased significantly (+6 +/- 6 versus +1 +/- 1 mmHg; p = 0.008) only in this group during follow up.

CONCLUSIONS

Patients with mismatch have less symptomatic improvement and worse hemodynamics that continue to deteriorate with time. However, medium-term prognosis (up to seven years) is relatively good. Further studies are necessary to determine the longer-term effects of mismatch on morbidity and mortality.

Squamous cell tumors and ocular prostheses

Conjunctival squamous cell carcinoma is an infrequent tumor. It has been reported to occur in association with actinic damage and chronic irritation. To the authors' knowledge, however, this tumor has not been reported secondary to poorly fitting ocular prostheses. Two patients were studied in whom conjunctival squamous cell carcinoma had developed. In both instances, the patient had been enucleated and fitted with an ocular prosthesis more than 40 years before tumor development. Histopathologic evaluation of each tumor revealed its squamous cell origin. In one of the patients, the tumor was found to be metastatic to the ipsilateral parotid gland, an uncommon finding. The authors attempted to identify risk factors that may have contributed to the development of these tumors. Aside from the poor fit of the prostheses, neither patient had significant risk factors for the development of conjunctival squamous cell carcinoma. It is concluded that a new, sanguineous conjunctival discharge or focal eyelid swelling after years of prosthetic wear may not be due to mechanical irritation alone. The onset of these symptoms, especially years after the initial fitting of an ocular prosthesis, should prompt a thorough investigation of its cause.

Home relines and residual ridge resorption

Two cases of patients who have relined their complete dentures with home-applied materials in an attempt to improve the denture stability are discussed. The resultant damage to the residual tissues is described. A review of the literature on the effects of home relines leads to suggestions for the regular review of patients who wear complete dentures.