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Background Certain cases of superior semicircular canal dehiscence or benign paroxysmal positional vertigo can be treated by plugging of the affected semicircular canal. However, the extent of the impact on vestibular function and hearing during postoperative follow-up is not known. Objective To evaluate the evolution of vestibular function and hearing after plugging of a semicircular canal. Methods Six patients underwent testing before and 1 week, 2 months, and 6 months after plugging of the superior or posterior semicircular canal. Testing included caloric irrigation test, video Head Impulse Test (vHIT), cervical and ocular Vestibular Evoked Myogenic Potentials (VEMPs) and audiometry. Results Initially, ipsilateral caloric response decreased in all patients and vHIT vestibulo-ocular reflex (VOR) gain of each ipsilateral semicircular canal decreased in 4/6 patients. In 4/6 patients, postoperative caloric response recovered to > 60% of the preoperative value. In 5/6 patients, vHIT VOR gain was restored to > 85% of the preoperative value for both ipsilateral non-plugged semicircular canals. In the plugged semicircular canal, this gain decreased in 4/5 patients and recovered to > 50% of the preoperative value. Four patients preserved cervical and ocular VEMP responses. Bone conduction hearing deteriorated in 3/6 patients, but recovered within 6 months postoperatively, although one patient had a persistent loss of 15 dB at 8 kHz. Conclusion Plugging of a semicircular canal can affect both vestibular function and hearing. After initial deterioration, most patients show recovery during follow-up. However, a vestibular function loss or high-frequency hearing loss can persist. This stresses the importance of adequate counseling of patients considering plugging of a semicircular canal.

Objective. Several lumped and distributed parameter models of the inner ear have been proposed to improve vestibular implant stimulation. The models should account for all significant physical phenomena that influence the current propagation, such as the electrical double layer (EDL) and medium polarization. The electrical properties of the medium are reflected in the electrical impedance; therefore, the study aimed to measure the impedance in the guinea pig inner ear and construct its equivalent circuit. Approach. The electrical impedance was measured from 100 Hz to 50 kHz between a pair of platinum electrodes immersed in 0.9% NaCl saline solution using sinusoidal voltage signals. The Randles circuit was fitted to the measured impedance in the saline solution in order to estimate the EDL parameters ( C , W , a n d R c t ) of the electrode interface in saline. Then, the electrical impedance was measured between all combinations of the electrodes located in the semicircular canal ampullae and the vestibular nerve in the guinea pig in vitro. The extended Randles circuit considering the medium polarization ( R i , R e , C m ) together with EDL parameters ( C , R c t ) obtained from the saline solution was fitted to the measured impedance of the guinea pig inner ear. The Warburg element was assumed negligible and was not considered in the guinea pig model. Main results. For the set-up used, the obtained EDL parameters were: C = 27.09 * 10 − 8 F , R c t = 18.75 k Ω . The average values of intra-, extracellular resistances, and membrane capacitance were R i = 4.74 k Ω , R e = 45.05 k Ω , C m = 9.69 * 10 − 8 F , respectively. Significance. The obtained values of the model parameters can serve as a good estimation of the EDL for modelling work. The EDL, together with medium polarization, plays a significant role in the electrical impedance of the guinea pig inner ear, therefore, they should be considered in electrical conductivity models to increase the credibility of the simulations.

Background Most questionnaires currently used for assessing symptomatology of vestibular disorders are retrospective, inducing recall bias and lowering ecological validity. An app-based diary, administered multiple times in daily life, could increase the accuracy and ecological validity of symptom measurement. The objective of this study was to introduce a new experience sampling method (ESM) based vestibular diary app (DizzyQuest), evaluate response rates, and to provide examples of DizzyQuest outcome measures which can be used in future research. Methods Sixty-three patients diagnosed with a vestibular disorder were included. The DizzyQuest consisted of four questionnaires. The morning- and evening-questionnaires were administered once each day, the within-day-questionnaire 10 times a day using a semi-random time schedule, and the attack questionnaire could be completed after the occurrence of a vertigo or dizziness attack. Data were collected for 4 weeks. Response rates and loss-to-follow-up were determined. Reported symptoms in the within-day-questionnaire were compared within and between patients and subgroups of patients with different vestibular disorders. Results Fifty-one patients completed the study period. Average response rates were significantly higher than the desired response rate of > 50% (p Conclusion The DizzyQuest is able to capture vestibular symptoms within their psychosocial context in daily life, with little recall bias and high ecological validity. The DizzyQuest reached the desired response rates and showed different disease profiles between subgroups of patients with different vestibular disorders. This is the first time ESM was used to assess daily symptoms and quality of life in vestibular disorders, showing that it might be a useful tool in this population.

Experimental data on electric signal transmission through tissues of the vestibular organ of a guinea pig are presented. Stimulating electrodes are implanted in three ampullae of semicircular canals to which an alternating voltage of 170 mV is applied. The receiving electrode is implanted in the termination of vestibular nerves. The impedance of the vestibular organ tissues has been measured depending on the stimulating signal frequency. It is shown that the amplitude phase characteristics of the resulting signal at the termination of the vestibular nerves depend on the position of the stimulating electrodes and on the stimulating signal frequency. The presence of conductive disturbance currents and their influence on the resulting signal waveforms are established. A method for eliminating the influence of the conductive disturbance currents by means of application of additional electric pulses with a certain phase shift to the stimulating electrodes is suggested.

A detailed electric model of current transmission through vestibular labyrinth tissues is suggested based on the anatomic structure of the labyrinth taking into account electrophysical properties of hair and basilar cells of neuroepithelium. Formulas for the impedance of the vestibular organ are derived and phase shifts of the stimulating current are calculated based on experimental data on the electrophysical and anatomic characteristics of vestibular labyrinth tissues of a guinea pig. The dispersion of the impedance is investigated for the frequencies in the range 101–5·104 Hz. It is shown that the phase shift of the current relative to the voltage applied between the electrode and the vestibular nerve is nonmonotonic in character and depends on the frequency. A minimum negative phase shift of the current is observed at f = 200 Hz. Taking into account of the cellular structures of the hair and basilar cells in the electric circuit shows that in the examined frequency range they bring significant contribution to the total impedance. The suggested electric model and the results of calculations can provide the basis for diagnostics of vestibular labyrinth diseases and design of vestibular implants of a new type.

Background/objective Different testing paradigms have been proposed to investigate perceptual self-motion thresholds. They can differ regarding the amount of possible motions that patients have to choose from. Objective of this study was to compare the two-option paradigm and twelve-option paradigm, to investigate whether reducing the choice options significantly influences the reported thresholds of self-motion perception of healthy subjects. Methods Thirty-three volunteers with no prior vestibular complaints were included and sequentially tested with both paradigms at a random sequence. Perceptual self-motion thresholds were measured using a hydraulic motion platform in the absence of external visual and auditory cues. The platform delivered twelve different movements: six translations and six rotations. Each subject had to report the correct type and direction of movements. Thresholds were determined by a double confirmation of the lowest threshold, in combination with a double rejection of the one-step lower stimulus. Perceptual self-motion thresholds of both paradigms were compared using the mixed model analysis. Results The twelve-option paradigm showed significantly higher reported thresholds for yaw rotations and translations left, right and down (p Conclusion Reported thresholds of self-motion perception of healthy subjects are influenced by the testing paradigm. The twelve-option paradigm showed significantly higher thresholds than the two-option paradigm. Results obtained with each testing paradigm should, therefore, be compared to paradigm-specific normative data.

Background The DizzyQuest, an app-based vestibular diary, provides the opportunity to capture the number and nature of vertigo attacks in daily life. To accomplish this, the DizzyQuest provides different strategies: event sampling using an attack questionnaire, and time sampling using an evening questionnaire. Objective of this study was to investigate whether the number and nature of reported vertigo attacks was comparable between the two questionnaires. Methods Fifty-seven patients, who reported vertigo attacks, used the DizzyQuest for on average 24 days. The number and nature (including symptoms, triggers and duration) of vertigo attacks were compared between the attack and the evening questionnaire. Results The attack questionnaire was used 192 times. In contrast, at least 749 new vertigo attacks were reported in 446 evening questionnaires. A vertigo attack was not always reported in both questionnaires during the same day. Vertigo attacks that were most likely captured by both questionnaires were not always reported the same in both questionnaires regarding triggers and duration. Conclusion Event sampling using an attack questionnaire has low recall bias and, therefore, reliably captures the nature of the attack, but induces a risk of under-sampling. Time sampling using an evening questionnaire suffers from recall bias, but seems more likely to capture less discrete vertigo attacks and it facilitates registration of the absence of vertigo attacks. Depending on the clinical or research question, the right strategy should be applied and participants should be clearly instructed about the definition of a vertigo attack.

ObjectiveTo optimize the current diagnostic and treatment procedures for patients with bilateral vestibulopathy (BV), this study aimed to determine the complete spectrum of symptoms associated with BV.MethodA prospective mixed-method study design was used. Qualitative data were collected by performing semi-structured interviews about symptoms, context, and behavior. The interviews were recorded and transcribed until no new information was obtained. Transcriptions were analyzed in consensus by two independent researchers. In comparison to the qualitative results, quantitative data were collected using the Dizziness Handicap Inventory (DHI), Hospital Anxiety and Depression Scale (HADS) and a health-related quality of life questionnaire (EQ-5D-5L).ResultsEighteen interviews were transcribed. Reported symptoms were divided into fourteen physical symptoms, four cognitive symptoms, and six emotions. Symptoms increased in many situations, such as darkness (100%), uneven ground (61%), cycling (94%) or driving a car (56%). These symptoms associated with BV often resulted in behavioral changes: activities were performed more slowly, with greater attention, or were avoided. The DHI showed a mean score of severe handicap (54.67). The HADS questionnaire showed on average normal results (anxiety = 7.67, depression = 6.22). The EQ-5D-5L demonstrated a mean index value of 0.680, which is lower compared to the Dutch age-adjusted reference 0.839 (60–70 years).ConclusionBV frequently leads to physical, cognitive, and emotional complaints, which often results in a diminished quality of life. Importantly, this wide range of symptoms is currently underrated in literature and should be taken into consideration during the development of candidacy criteria and/or outcome measures for therapeutic interventions such as the vestibular implant.

Recent research has shown promising results for the development of a clinically feasible vestibular implant in the near future. However, correct electrode placement remains a challenge. It was shown that fluoroscopy was able to visualize the semicircular canal ampullae and electrodes, and guide electrode insertion in real time. Ninety-four percent of the 18 electrodes were implanted correctly (

Vestibular implants are devices designed to rehabilitate patients with a bilateral vestibular loss (BVL). These patients lack a properly functioning vestibulo-ocular reflex (VOR), which impairs gaze stabilization abilities and results in an abnormal loss of visual acuity (VA) in dynamic situations (i.e., severely limiting the patient's ability to read signs or recognize faces while walking). We previously demonstrated that the VOR can be artificially restored in a group of BVL patients fitted with a prototype vestibular implant. This study was designed to investigate whether these promising results could be translated to a close-to reality task, significantly improving VA abilities while walking. Six BVL patients previously implanted with a vestibular implant prototype participated in the experiments. VA was determined using Sloan letters displayed on a computer screen, in four conditions: (1) with the patient standing still without moving (static), (2) while the patient was walking on a treadmill at constant speed with the vestibular implant prototype turned off (systemOFF), (3) while the patient was walking on a treadmill at constant speed with the vestibular implant prototype turned on providing coherent motion information (systemON(motion)), and (4) a "placebo" condition where the patient was walking on a treadmill at constant speed with the vestibular implant prototype turned on providing reversed motion information (systemON(sham)). The analysis (one-way repeated measures analysis of variance) revealed a statistically significant effect of the test condition [F-(3,F- 12) = 30.5. p

Objective Hyperostosis cranialis interna (HCI) is an autosomal dominant sclerosing bone dysplasia affecting the skull base and the calvaria, characterized by cranial nerve deficits due to stenosis of neuroforamina. The aim of this study is to describe the value of several neurophysiological, audiometric and vestibular tests related to the clinical course of the disorder. Methods Ten affected subjects and 13 unaffected family members were recruited and tested with visual evoked potentials, masseter reflex, blink reflex, pure tone and speech audiometry, stapedial reflexes, otoacoustic emissions, brainstem evoked response audiometry and electronystagmography. Results Due to the symmetrical bilateral nature of this disease, the sensitivity of visual evoked potentials (VEPs), masseter reflex and blink reflex is decreased (25–37.5%), therefore reducing the value of single registration. Increased hearing thresholds and increased BERA latency times were found in 60–70%. The inter-peak latency I–V parameter in BERA has the ability to determine nerve encroachment reliably. 50% of the patients had vestibular abnormalities. No patient had disease-related absence of otoacoustic emissions, because the cochlea is not affected. Conclusion In patients with HCI and similar craniofacial sclerosing bone dysplasias we advise monitoring of vestibulocochlear nerve function with tone and speech audiometry, BERA and vestibular tests. VEPs are important to monitor optic nerve function in combination with radiological and ophthalmologic examination. We do not advise the routine use of blink and masseter reflex.

Many medical doctors consider vertigo and dizziness as the major, almost obligatory complaints in patients with vestibular disorders. In this chapter, we will explain that vestibular disorders result in much more diverse and complex complaints. Many of these other complaints are unfortunately often misinterpreted and incorrectly classified as psychogenic. When we really understand the function of the vestibular system, it becomes quite obvious why patients with vestibular disorders complain about a loss of visual acuity, imbalance, fear of falling, cognitive and attentional problems, fatigue that persists even when the vertigo attacks and dizziness decreases or even disappears. Another interesting new aspect in this chapter is that we explain why the function of the otolith system is so important, and that it is a mistake to focus on the function of the semicircular canals only, especially when we want to understand why some patients seem to suffer more than others from the loss of canal function as objectified by reduced caloric responses.

Objective. The vestibular system provides essential information about balance and spatial orientation via the brain to other sensory and motor systems. Bilateral vestibular loss significantly reduces quality of life, but vestibular implants (VIs) have demonstrated potential to restore lost function. However, optimal electrical stimulation strategies have not yet been identified in patients. In this study, we compared the two most common strategies, pulse amplitude modulation (PAM) and pulse rate modulation (PRM), in patients. Approach. Four subjects with a modified cochlear implant including electrodes targeting the peripheral vestibular nerve branches were tested. Charge-equivalent PAM and PRM were applied after adaptation to baseline stimulation. Vestibulo-ocular reflex eye movement responses were recorded to evaluate stimulation efficacy during acute clinical testing sessions. Main results. PAM evoked larger amplitude eye movement responses than PRM. Eye movement response axes for lateral canal stimulation were marginally better aligned with PRM than with PAM. A neural network model was developed for the tested stimulation strategies to provide insights on possible neural mechanisms. This model suggested that PAM would consistently cause a larger ensemble firing rate of neurons and thus larger responses than PRM. Significance. Due to the larger magnitude of eye movement responses, our findings strongly suggest PAM as the preferred strategy for initial VI modulation.

The handicap resulting from a bilateral vestibular deficit is often underestimated. In most cases the deficit settles gradually. Patients do not understand what is happening to them and have many difficulties to describe their symptoms. They have to consult several doctors with different medical specialties before diagnosis. Once the diagnosis is made there is no biological way to "repair'' the deficient vestibular apparatus and vestibular exercises are mildly effective. Attempts have been made to help patients using substitution devices replacing the defective vestibular information by tactile or acoustic cues. Currently, efforts are being made towards the development of a vestibular implant, conceptually similar to the cochlear implant for the rehabilitation of deaf patients. In recent years, several experiments on animal models have demonstrated the feasibility of this project. This paper reports the steps accomplished in human experiments and the main results obtained in our laboratory.

Introduction: The impact of muscle contraction upon head movements induced by a forward acceleration was studied as a model for low impact car-accidents. The purpose of our research is to examine: (i) whether and by which mechanism neck muscle contraction is induced after onset of the movement; and (ii) if voluntary neck muscle contraction prior to the movement affects head motion. Subjects and methods: Eight healthy volunteers (mean age 21.4 years) were included in this study. Volunteers were sitting on a standard car seat mounted on a sled. The computer-controlled, motor-driven sled was forward accelerated with 0.6 g. In test series 1, head and body movement were detected with a standard video camera (20 ms per frame) and accelerometers mounted on the head without interference with muscle activity. Muscle activation was detected by simultaneous measurement of surface EMG of m. splenius capitis, m. trapezius (descending part), m. scalenis medius, m. sternocleido mastoideus, m. digastricus (anter...

OBJECTIVES: The objectives were to study the absorption kinetics and pharmacodynamics of two oral formulations of flecainide in patients with atrial fibrillation (AF) and to assess the relationship between pharmacokinetic parameters and the efficacy in restoring sinus rhythm. METHODS: The data of 54 patients included in a randomised, open, parallel-group study were used. Patients received an oral solution containing 300 mg flecainide and 20 mg cisapride or three tablets each containing 100 mg flecainide. The pharmacokinetic profile of flecainide was fitted using a one-compartment model with lag-time and first-order absorption. RESULTS: The tablets gave a maximum concentration (C (max fit)) of 0.43+/-0.14 mg/l at 2.37+/-1.20 h. The oral solution resulted in a much faster peak concentration at 1.05+/-0.71 h (P

Deformation of the extradural space and the possibility of impression upon the dural sac during atlanto-axial rotation are investigated. Atlanto-axial rotation leads to a reduction in the cross-sectional area of the bony spinal canal of approximately 40 %. Atlanto-axial rotation was recorded by endocanalar views from a video camera fixed inside the skull of six unembalmed cadavers. Axial thin-section T1-weighted MRI slice sets were acquired from three volunteers (mid-position and maximal left and right rotation of the head and cervical spine). The axial cross-sectional areas of the bony spinal canal, dural sac and spinal cord were measured. In two other persons post-gadolinium contrast-enhanced T1-weighted MRI volume scans with fat-suppression prepulse were acquired (mid-position and rotation) to determine venous contents of the extradural space. The 50:50 ratio between left and right extradural halves in mid-position changed to an ipsilateral:contralateral ratio of 20:80 in maximum rotation at the level just above the lateral C1-C2 joints. Directly below these joints the opposite occurred. The post-contrast studies showed an enhancing internal vertebral venous plexus (IVVP), which almost completely occupied the extradural space at the atlanto-axial level. This could not be shown in the cadaver experiments, because of absence of blood and cerebrospinal fluid (CSF) pressure. During atlanto-axial rotation blood displacement in the IVVP allows major deformations of the extradural space. This prevents dural sac impression.

The present study investigates the diagnostic value of rotatory computed tomography (CT) examinations in normal subjects and patients with whiplash associated disorders (WAD), with the aim of reproducing earlier findings of rotatory CT studies. Forty-seven WAD patients with persistent complaints after a rear-end collision (non-cranial contact acceleration/deceleration trauma) were enrolled in this study. To guarantee a maximally homogeneous study population, only WAD patients with a marked passive cervical retroflexion restriction were included. Transversal CT slices in left and right rotation were made for all cervical levels (the skull included). CT slices in neutral position were used to reconstruct partially depicted vertebrae. Absolute rotatory values were estimated according the method of Penning and Dvorak. For all levels the relative rotatory (RR) value was calculated by dividing absolute rotation values of a particular cervical level by the corresponding total cervical rotation. The measuring error was estimated by comparing the findings of two separately performed measuring procedures. Two age groups of WAD patients were formed. A younger group was matched for age with 26 normal healthy volunteers (the original data of an earlier study). The use of neutral CT slices for reconstruction of a partially depicted cervical vertebra resulted in a measurement error of 1.9 degrees at the level of C0/C1 (occiput/atlas) and 3.5 degrees at C1/C2. Suspected hypermobility as defined by Dvorak was rare in our WAD patients (6.4% C0/C1 and 10.6% C1/C2). RR values at C0/C1 were significantly larger in 79% of the WAD patients. Discriminant analysis of the RR values showed 80% correctly classified WAD patients. Only 11.5% of the normal subjects were classified as false-positive. Since no hypermobility was found at C1/C2, a traumatic lesion of the alar ligaments is less likely. It was concluded that the use of absolute rotation values in rotatory CT scan procedures has a low diagnostic value in WAD patients. Excessive RR values were only found at C0/C1. A traumatic lesion of the ligaments at C0/C1, which prevent vertical translation of the skull with regard to the atlas, is hypothesised. The results of the discriminant analysis of the RR values make this method applicable for the individual WAD patient in daily practice.

Ocular counterrolling (OCR) induced by lateroflexion, whole body roll, eccentric rotation or translational acceleration has been explored and promoted as an indicator of the vestibular statolith function. Quantification of eye torsion induced by stimulation of the statolith organ has recently become available for broad clinical application thanks to the development of video nystagmography. The most simple way and maybe clinically the most attractive procedure to induce OCR could have been by changing the orientation of the statolith system relative to the gravitation vector, i.e. by lateroflexion of the head. However, irrespective of the visual condition, irrespective of the type of head roll, static or dynamic, OCR showed considerable inter- and intravariability. Findings in healthy subjects and patients indicate that according to our current insight, measurement of OCR induced by lateroflexion or whole body roll has a limited sensitivity and specificity. The normal range of OCR in healthy subjects is large (4.5–9.0% and could be interpreted as a functional asymmetry in statolith function that does not really exist. At present there are insufficient clinical data available to judge the clinical relevance of this test. OCR induced by sideward translations has the advantage over the previously described techniques that it allows an evaluation of the frequency characteristics of the statolith function. Major problems with this technique are that the equipment required is complex and expensive, that a appropriate head fixation is difficult and that responses are quite small. So far, the scarce clinical data do not yet point to a clear clinical relevance of this approach.

OBJECTIVE To describe the causes and circumstances of death regarding patients who died in 1994 and 1995 while on a waiting list for cardiac surgery in the Netherlands. DESIGN Retrospective multicentre case study. SETTING 11 Dutch cardiac surgery centres. PATIENTS All patients reported as dying while on the waiting list for cardiac surgery in 1994 and 1995. MAIN OUTCOME MEASURES Classification of death by an independent adjudication committee into “erroneously reported”, “waiting list related” or “not waiting list related”. Death was judged as “waiting list related” if the clinical course would have been substantially different if there had been unrestricted surgical capacity. RESULTS 138 and 129 deaths were reported in 1994 and 1995, respectively. 43 deaths (16%) were considered as erroneously reported. 181 of the remaining 224 cases were adjudicated as waiting list related. Median time from acceptance for surgery to death was 35 days (interquartile range 14–75 days). 97 of 181 deaths occurred within six weeks following addition to the waiting list. The estimated incidence of death ranged from 1.33 per 1000 patient-weeks during weeks 2–4 to 0.68 per 1000 patient-weeks after 12 weeks. CONCLUSIONS The causes and circumstances of death are waiting list related for approximately 100 patients per year in the Netherlands. At least half of the deaths may occur within the first six weeks. Waiting lists for cardiac surgery engender high risks for the patients involved.

His-bundle ablation followed by pacemaker implantation is today a widely accepted therapeutic choice when drug refractoriness of symptomatic AF is evident. The selection of pacing mode in patients suffering from paroxysmal AF is still controversial. Preservation of AV synchrony is an attractive option in patients with paroxysmal AF who undergo His-bundle ablation. The purpose of this study was to examine prospectively the contribution of VDDR pacing for preservation of AV synchrony. After His-bundle ablation a VDDR pacing system was implanted in 17 patients with paroxysmal AF, and all antiarrhythmic drugs were withdrawn. The endpoint of the study was defined as the onset of chronic AF. To document the onset of chronic AF 48-hour Holter recordings were made every 6-8 weeks. After a mean followup of 18.2 (range 14-21) months, VDDR pacing is still operative in 13 patients (77%). Four patients developed chronic AF after a mean follow-up of 6 months. Of several baseline characteristics, only the intraatrial P wave at implantation was significantly smaller in patients developing chronic AF than in patients in whom the VDDR mode is still operative. This pilot study suggests that VDDR pacing is an attractive pacing method for patients with paroxysmal AF after His-bundle ablation. A low intraatrial P wave electrogram at implant was associated with a higher risk for the development of chronic AF.

AIMS: Angiographic studies on the natural course of both focal and diffuse coronary atherosclerosis have not been performed before, but can both be assessed by quantitative coronary angiography. The objective of this study was to describe the natural course of focal and diffuse coronary atherosclerosis over time. METHODS AND RESULTS: In 129 patients with mild coronary artery disease, but not on lipid-lowering medication, three coronary angiograms were made each 2 years apart. Nine hundred and sixty five angiographically diseased and non-diseased segments were analysed by quantitative coronary angiography. Mean lumen diameter and minimal lumen diameter were used as measures of diffuse and focal coronary atherosclerosis. Mean lumen diameter and minimum lumen diameter decreased by 0.02 and 0.03 mm per year. The rate of progression was similar in the angiographically non-diseased, as in the mildly and moderately diseased segments. Progression of diffuse coronary atherosclerosis was largest in severely stenosed lesions (percentage diameter stenosis > or = 50%) and in the right coronary artery with a loss of 0.19 mm and 0.16 mm in mean lumen diameter. Progression of focal disease was most prominent in new and mild lesions and the right coronary artery, with a decrease in minimum lumen diameter of 0.34 mm and 0.22 mm. In most subgroups, progression occurred gradually over time. On a per segment level, progression and the occurrence of new lesions occurred in 4.4% and 4.2%. Regression and disappearance of a lesions was found in 2.3% and 1.9%. On a per patient level, 36% were progressors, 12% had a mixed response, 36% were stable, and 16% were regressors. CONCLUSION: Diffuse and focal coronary atherosclerosis progressed at the same rate in the first and second 2 years in stenosed and non-stenosed segments. The rate of coronary atherosclerosis progression was small, but was higher for focal than for diffuse disease. A minority of lesions progressed and spontaneous regression was rare.

OBJECTIVE: To evaluate exercise capacity of patients with chronic atrial fibrillation in whom His bundle ablation followed by ventricular rate response pacing (VVIR) was carried out because of drug refractoriness. DESIGN: Prospective study. PATIENTS: 25 consecutive patients, all with chronic symptomatic drug refractory atrial fibrillation, underwent His bundle ablation. Before this intervention all patients were on antiarrhythmic drugs to attain acceptable heart rate control and to relief symptoms. MAIN OUTCOME MEASURES: Exercise capacity, including measurements of VO2, was examined before and after a mean interval of seven months following His bundle ablation. RESULTS: Exercise capacity after His bundle ablation increased from a mean of 109 (SD 49) W to 118 (46) W (P < 0.002), but VO2 at peak exercise did not change significantly. Maximum exercise capacity was achieved with a significantly lower maximum driven heart rate than the spontaneous heart rate before ablation. CONCLUSIONS: Exercise capacity of patients who underwent His bundle ablation followed by VVIR pacing remained unchanged or improved during a mean follow up of seven months. Larger patient populations with longer follow up are necessary to examine determinants of improved exercise capacity.

Balance deteriorates with age, and may eventually lead to falling accidents which may threaten independent living. As Taekwondo contains various highly dynamic movement patterns, taekwondo practice may sustain or improve balance. Therefore, in 24 middle-aged healthy volunteers (40-71 year) we investigated effects of age-adapted taekwondo training of one hour a week during one year on various balance parameters, such as: motor orientation ability (primary outcome measure), postural and static balance test, single leg stance, one leg hop test, and a questionnaire. Motor orientation ability significantly increased in favor of the antero-posterior direction with a difference of 0.62 degrees towards anterior compared to pre-training measurement, when participants corrected the tilted platform rather towards the posterior direction; female gender being an independent outcome predictor. On postural balance measurements sway path improved in all 19 participants, with a median of 9.3 mm/sec (range 0.71-45.86), and sway area in 15 participants with 4.2 mm²/sec (range 17.39-1.22). Static balance improved with an average of 5.34 seconds for the right leg, and with almost 4 seconds for the left. Median single leg stance duration increased in 17 participants with 5 seconds (range 1-16), and in 13 participants with 8 seconds (range 1-18). The average one leg hop test distance increased (not statistically significant) with 9.5 cm. The questionnaire reported a better ‘ability to maintain balance’ in sixteen. In conclusion, our data suggest that age-adapted Taekwondo training improves various aspects of balance control in healthy people over the age of forty.

* Institute for Medical Technology Assessment, Erasmus University, Rotterdam, |STIC'ARES CardiovascularResearch Foundation, Rotterdam, %St Antonious Hospital, Nieuwegein, \\de Wever Hospital, Heerlen, ^RijnstateHospital DH, Arnhem, The NetherlandsObjective To estimate the costs and effects of preventivetreatment with captopril compared with the current treat-ment policy in patients with asymptomatic left ventriculardysfunction after a myocardial infarction.Methods Estimates of effects are based on the results of theSAVE trial. Costs are estimated on the basis of currenttreatment patterns in four Dutch hospitals. All knowledgeis incorporated in a mathematical model extrapolating theSAVE results to 20 years.Results and conclusions Captopril treatment is expectedto increase survival at certain costs. The average additionalcosts per patient are estimated at DF1 2 491 in 4 years andat DF1 8 723 in 20 years of treatment. Costs per additionalsurvivor after 4 years are estimated at DF1 69 126. Afterextrapolation of the results of the SAVE trial to 20 years,costs per life-year gained can be estimated at DF1 15 799.From univariate sensitivity analysis it appears that theresults are highly sensitive for the costs of treatment withcaptopril and the occurrence and prevention of clinicalheart failure. Varying all estimates randomly between upperand lower limits — in 5000 simulations — an estimate ofcosts per life-year gained of DF1 15 729 is made for 20 yearsof treatment, with 95% of all estimates between DF1 0 andDF1 50 000. On a national level, undiscounted costs areexpected to increase up to approximately DF1 42 millionannually during the first 40 years after introduction of thepreventative strategy.(Eur Heart J 1996; 17: 731-740)Key Words: Captopril, heart failure, prevention,angiotensin-converting enzyme inhibitors, cost-effectiveness,simulation, model.

Die haufigste Form von Schwindel bei raschen Kopfbewegungen ist bei alteren Menschen der paroxysmale Lagerungsschwindel. Das Syndrom wird von vielen durch flottierende Statolithen im posterioren Bogengang erklart (Kanalolithiasis). Zur Behandlung des paroxysmalen Lagerungsschwindels sind verschiedene Medikamente aber auch Physiotherapie vorgeschlagen worden. 1988 stellten Semont et al. ein Manover vor, um eine Verlagerung des Konkrements von der Kupula in Richtung des Utriculus zu erreichen. Symptome, Atiologie und Therapie (Semont-Manover) des paroxysmalen Lagerungsschwindels werden anhand eines klinischen Falles beschrieben.

So far it has only been possible to detect horizontal and vertical eye movements during real time; torsional eye movements have to be calculated from video-tape that have been processed several times, and each investigation takes considerable time. We developed a real time binocular infra red video eye tracker for routine clinical examination which allows real time graphical visualization of horizontal, vertical and torsional eye movements with a bandwidth of 12 Hz (25 Hz refresh frequency). Eye movements in three dimensions can now be obtained as easy as has been done before with electronystagmography for the horizontal component. In contrast to previous systems described, we analyze only those parts of the video-frame that are essential for detection of all three eye movements. This results in a huge data-reduction accompanied by a speed-up of analysis. The black pupil centre is detected by an iterative process of analyzing several horizontal and vertical lines of the even video field. The algorithm searches for regions of minimal intensity. Horizontal and vertical eye rotation is then calculated and transformed into Fick's coordinates. Based upon the centre of the pupil four concentric segments are defined in the iris to detect torsion and to enable correction for false rotation. Torsion is detected by cross-correlation of each segment and estimated from the outcome of the correlation coefficients. All transformations are established by predefined stored transformation matrices thus making real time calculations for transformation unnecessary. After corrections for eccentricity and assuming that fixation of the subjects tested was perfect, accuracy appears to be within 0.3 degrees-1.0 degrees for all three dimensions. Linearity after all corrections is within 4-9% within a visual field of 60 x 40 degrees (horizontal x vertical).

The Vestibular Autorotation Test (VAT) is a relatively easy method for testing the Vestibulo Ocular Reflex (VOR) at higher frequencies by asking the patient to actively shake his/her head from side to side (jaw) with increasing frequency. In this study we investigated reproducibility and clinical applicability of this method and quantified gain and phase of the VOR in normal subjects. We studied the VOR in 33 subjects over a frequency range from 2 to 6 Hz. Ten subjects were investigated with an angular rate sensor mounted on a headband. In this group the velocity gain tended to decrease at higher frequencies and phase lag increased slightly. In a second experiment (2 subjects) head velocity was detected simultaneously by an angular sensor fixed to a headband and an identical sensor attached to a bite board. It was shown that the gain of the VOR in the first group was underrated and phase shift overrated due to slippage of the headband fixed rate sensor. Therefore in a third experiment, 21 subjects were investigated with the rate sensor attached to a bite board only. In this group VOR gain was close to unity and phase was close to 0 degrees (180 degrees out of phase) from 2 up to 6 Hz. In contrast to other studies, a considerable number of subjects were unable to reach shaking frequencies above 4 Hz. Our results agree with those of recently published reports and disagree with others, both using a headband. This is interpreted as being due to difficulties in sensing head velocity accurately.vestibular autorotation is an accurate and reproducible way of testing the high frequency range of the vestibulo-ocular reflex, provided that head velocity is measured by a bite board. Our present work is focused on determining the high frequency characteristics of the VOR in patients suffering from vertigo.

Seit EinfUhrung des Rotationstestes fUr die klinische vestibulAre Analyse durch BArAny (1907) wurden zahlreiche Versuche unternommen, um Rotationstests zu entwickeln, die in der Lage sind, Uber den vestibulookulAren Reflex (VOR) quantitative Informationen zu erhalten. Die meisten klinischen Rotationstests werden mit einer Oszillationsfrequenz bis 0,5 Hz durchgefUhrt, obwohl Kopfbewegungen wAhrend AktivitAten im tAglichen Leben Werte bis 8 Hz erreichen kOnnen. Diese Studie hat die VOR-Charakteristika von aktiven gegenUber passiven hochfrequenten Kopfrotation en bis zu 6 Hz in jungen, gesunden Probanden verglichen. WAhrend der aktiven Kopfrotation blieb der VerstArkungsfaktor 1 nahezu einheitlich, und ein geringes Vorauseilen der Phasen im gesamten Frequenzbereich war vorhanden. Doch erreichte nicht jeder Proband 6 Hz. WAhrend der passiven Kopfrotation, die durch einen computergesteuerten KopfschUttler erreicht wurde, fiel der VerstArkungsfaktor auf 0,82 bei 6 Hz und die Phasenverschiebung blieb bei 0°. Die vorliegende Arbeit hat ihren Schwerpunkt in der Quantifizierung des VOR wAhrend aktiver und passiver hochfrequenter Kopfrotation in verschiedenen Patientengruppen, die unter Schwindel leiden. Damit hoffen wir, zwischen Patienten und normalen Probanden durch einen der oben beschriebenen Tests unterscheiden zu kOnnen. Besonders die aktive Kopfrotation ist eine billige und einfach durchfUhrbare Methode in der klinischen Routine.

BACKGROUND The purpose of this study was to assess the value of body surface mapping and the standard 12-lead ECG in localizing the site of origin of postinfarction ventricular tachycardia (VT) during endocardial pace mapping of the left ventricle. METHODS AND RESULTS Simultaneous recordings of 62-lead body surface QRS integral maps and scalar 12-lead ECG tracings were obtained in 16 patients with prior myocardial infarction during a total of 26 distinct VT configurations and during subsequent left ventricular catheter pace mapping at 9 to 24 different endocardial sites. Anatomic pacing site locations were computed by means of a biplane cineradiographic method and plotted on a polar projection of the left ventricle. The QRS integral map and the QRS complexes of the 12 standard leads of each VT morphology obtained in a particular patient were compared independently with the different paced QRS integral maps and paced QRS complexes of the 12-lead ECG generated in that same patient. The stimulus site locations of the best matching paced QRS integral map and paced QRS complexes of the 12-lead ECG were indicated on the polar projection and subsequently compared with the endocardial location of the corresponding site of VT origin identified during intraoperative (surgical ablation) or catheter activation sequence mapping (catheter ablation). The localization resolution of pace mapping was established separately for each electrocardiographic technique by computing the size of endocardial areas with similar morphological features of the QRS complex. Pace mapping advocated with body surface mapping or the 12-lead ECG enabled adequate reproduction of the VT QRS morphology in 24 of 26 VTs (92%) and 25 of 26 VTs (96%), respectively. Activation sequence mapping identified the site of origin in 12 of 26 previously observed VT configurations (46%). Ten and 11 VTs were localized by activation sequence mapping and pace mapping combined with body surface mapping or the 12-lead ECG, respectively. Pace mapping applied with body surface mapping identified the site of origin correctly (distance < or = 2 cm) in 8 of 10 compared VTs (80%); an adjacent site (distance between 2 and 4 cm) or a disparate site (distance > or = 4 cm) was identified in the remaining 2 of 10 VTs (20%). Pace mapping used with the 12-lead ECG localized the site of origin correctly in 2 of 11 VTs (18%); the site of origin was identified correctly next to an additional adjacent site in 5 of 11 VTs (55%); and an adjacent site or a disparate site was found in 1 of 11 VTs (9%) and 2 of 11 VTs (18%), respectively. The difference in localization accuracy of both electrocardiographic techniques was statistically significant (P = .02). The mean size of endocardial areas where a comparable QRS morphology was obtained during pace mapping was 6.0 +/- 4.5 cm2 with the application of body surface mapping and 15.1 +/- 12.0 cm2 with the use of the 12-lead ECG. CONCLUSIONS These results demonstrate that application of the 62-lead instead of the 12-lead ECG during endocardial pace mapping enhances the localization resolution of this mapping technique and enables more precise identification of the site of arrhythmogenesis in the majority of compared postinfarction VT episodes.

Self-terminating ventricular fibrillation was recorded in a 47 year old woman without coronary artery or other structural heart disease. Reperfusion was thought to be responsible for the ventricular fibrillation because the arrhythmia started while the ST segment was returning to the baseline during an episode of silent ischaemia that was probably caused by coronary spasm. This case shows that potentially lethal arrhythmias can arise during reperfusion and that ventricular fibrillation during reperfusion may be self-terminating.

Video-oculography (VOG) is a frequently used clinical technique to detect eye movements. In this research, head mounted small video-cameras and IR-illumination are employed to image the eye. Many algorithms have been developed to extract horizontal and vertical eye movements from the video images. Designing a method to determine torsional eye movements is a more complex task. The use of IR-wavelengths required for illumination in certain clinical tests results in a very low image contrast. In such images, iris textures are almost invisible, making them unsuited for direct application of standard matching algorithms, which are used to calculate torsional eye movements. This research presents the design and implementation of a robust torsional eye movement detection algorithm for VOG. This algorithm uses a new approach to measure the torsional eye movement and is suitable for low contrast videos. The algorithm is implemented in a clinical device and its performance is compared to that of alternative techniques.

To improve electrocardiographic localization of the site of origin of ectopic left ventricular (LV) impulse formation in the heart with prior myocardial infarction, 62-lead body surface QRS integral maps were studied during LV pacing at a total of 221 endocardial sites in 14 patients with previous anterior (AMI), inferior (IMI), lateral (LMI), or anterior and inferior (AMI/IMI) myocardial infarction. The anatomic location of each pacing site was computed using digitized biplane fluoroscopic images and plotted on standardized LV endocardial polar projections. A data base of characteristic AMI and IMI mean QRS integral maps was developed after visually selecting subgroups with nearly identical QRS integral morphology from the ectopic activation sequences produced at 110 sites in eight patients with AMI and at 66 sites in four patients with IMI. Intrasubgroup pattern uniformity and intersubgroup pattern variability were statistically verified. The endocardial pacing site locations belonging to each AMI and IMI subgroup were depicted as segments on the respective LV polar projections. In patients with AMI, a total of 18 typical mean QRS integral patterns were obtained, whereas 22 different mean total QRS integral patterns showing more substantial intersubgroup variation were acquired in patients with IMI. Posterolateral regions exhibited a relatively low electrocardiographic sensitivity (six AMI and five IMI patterns) as compared with anteroseptal regions (12 AMI and 17 IMI patterns). Total QRS integral patterns obtained at 24 sites in one patient with LMI were largely compatible with the IMI mean total QRS integral patterns, whereas the majority of total QRS integral patterns acquired at 21 sites in one patient with AMI/IMI corresponded with the AMI mean total QRS integral patterns. The results show that total body surface QRS integral maps generated during LV pacing in patients with prior myocardial infarction cluster by pattern and that each QRS integral pattern is related to a circumscribed endocardial segment of ectopic impulse formation. The relation between a given QRS integral pattern and the position and size of the corresponding paced segment is dependent on infarct location. The present infarct-specific data base of characteristic total body surface QRS integral patterns provides a clinical tool to obtain detailed electrocardiographic localization of ventricular arrhythmias in patients with previous myocardial infarction.

A total of 1124 consecutive patients who were selected for coronary artery bypass graft surgery were studied. Of patients awaiting surgery (mean waiting time 98 days) 25 patients (2.2%) died before operation (mean waiting time 63 days). To assess patient characteristics predictive for early mortality before surgery, 25 deceased patients were analysed and compared to 50 controls matched for age, gender, type of surgery and waiting-list priority. Univariate analysis showed that the deceased patients had a higher rate of severe angina pectoris class III-IV (odds ratio (OR) 2.9), unstable angina prior to angiography (OR 4.8), cardiac enlargement on chest X-ray (OR 13.5), positive exercise testing of short duration (less than or equal to 6 min) (OR 6.0), coumarin treatment (OR 4.2), smoking (OR 3.0), severe left main or three-vessel disease (OR 4.1), abnormal end-diastolic volume (OR 3.1) and an abnormal left ventricular wall motion score (OR 3.0). Using multivariate analysis, cardiac enlargement (OR 14.4), positive exercise testing of short duration (OR 13.3), smoking (OR 8.7), coumarin treatment (OR 7.1), unstable angina (OR 6.5) and/or left main or three-vessel disease (OR 5.4) were independent predictors for death while awaiting coronary revascularisation. Thus, patients with the above mentioned independent characteristics have an increased short-term mortality while awaiting coronary bypass graft surgery. These indicators may contribute important information for determination of priority in high risk patients awaiting coronary artery bypass graft surgery.

Video-oculography (VOG) is a frequently used clinical technique to detect eye movements. In this research, head mounted small video-cameras and IR-illumination are employed to image the eye. The need for algorithms to extract the eye movements automatically from the video recordings is high. Many algorithms have been developed. However, to our knowledge, none of the current algorithms, is in all cases accurate and provides an indication when detection fails. While many doctors draw their conclusions based on occasional erroneous measurement outcomes too, this can result in a wrong diagnosis. This research presents the design and implementation of a robust, real-time and high-precision eye movement detection algorithm for VOG. But most importantly, for this algorithm a confidence measure is introduced to express the quality of a measurement and to indicate when detection fails. This confidence measure allows doctors in a clinical setting to see if the outcome of a measurement is reliable.

Doel van dit hoofdstuk is, behalve een goed inzicht in de functie van het vestibulaire systeem, een beter beeld te geven van de grote diversiteit aan problemen die een patient met een vestibulair functieverlies kan ervaren.