Biomedical subjects
Publications and source records attributed to A Böhm.
There are only a few reported cases of a pacemaker lead migrating inadvertently into the left atrium or ventricle. An unusual complication of unremoved, unwanted pacemaker lead is presented. The free tip of the lead caused cerebral embolism after perforating the interatrial septum.
Explore the source record for details and available documents.
A case of QT duration dependent T wave oversensing mimicking QRS undersensing and pacemaker malfunction is presented. This example indicates that interpretation of pacemaker ECG may be difficult, even in case of VVI pacemaker.
Atrial pacing (AP), despite its beneficial hemodynamic and antiarrhythmic effect, is still an underused mode of stimulation. The main purpose of this study was to evaluate the long-term results of AP. Sixty four patients (pts) with sinus node disease (28 male and 36 female: mean age 54.2; range: 44-88 years), 3.2% of the total implantation at our clinic were treated with AP between 1982-96. Criteria for atrial pacing were: no AV block in the history, no AV-block during carotid sinus massage, Wenckebach point > 130/min, left atrium < 50 mm, left ventricular EF > 40%. The indication for pacing was predominant sinus bradycardia (SB) in 34 pts and tachycardia-bradycardia syndrome (TBS) in 30 pts. Pts with TBS were on antiarrhythmic treatment, while most pts with SB received no antiarrhythmic drugs. All the pts were checked up at every 3-6 month. Sixty-two pts were followed for 3-154 (mean: 67) months, two pts were lost for follow-up. Repeated lead dislodgment occurred in two pts, which made a pacing mode change necessary. Four pts died during the follow-up period for non-cardiac reasons. At the end of the follow-up period the data of 60 pts were available for evaluation (33 pts with SB, 27 pts with TBS). All the pts with SB were in sinus rhythm, and no patient developed AV block by the end of the follow-up period. Seven out of 27 pts with TBS developed chronic atrial fibrillation, 3 out of them suffered a cerebral embolism; the remaining 20 pts were in sinus rhythm, and the number of paroxysmal attacks decreased significantly, which improved their quality of life significantly. Three pts in this group developed a temporary complete AV block, which regressed with decreasing the dosage of antiarrhythmic drugs. Atrial pacing is proved to be a safe and reliable treatment for sick sinus syndrome. Proper patient selection is crucial in preventing the development of AV conduction disturbance. Atrial stimulation had a satisfactory long-term antiarrhythmic effect in pts with sick sinus syndrome (SSS).
Explore the source record for details and available documents.
BACKGROUND: Photorefraktive keratectomy (PRK) is the most frequent refractive surgical procedure worldwide. The central corneal thickness is reduced due to removal of the anterior stroma, including Bowman's layer, with a laser beam. This procedure results in considerable alterations of the corneal structure. What does this mean for the mechanical properties of the cornea? METHODS: Intraocular pressure was increased via a 180 degrees tilt. Before and during this procedure, corneal topography was measured by photokeratoscopy. We examined 26 patients after PRK and 25 controls who had not undergone any surgical procedure. RESULTS: The corneal center flattened by 0.038 +/- 0.05 dpt (P > 0.05) in the PRK patients and by 0.187 +/- 0.045 dpt (P < 0.05) in the control group. PRK patients within 1 year after operation showed a minimal central corneal steepening, whereas PRK patients after more than 1 year showed a reaction similar to that in normal corneas (P < 0.05). CONCLUSION: Corneal stability is altered after PRK. After 1 year corneal stability seems to normalize due to stromal remodelling.
BACKGROUND: Keratoconus is associated with changes in the corneal structure, such as defects of Bowman's layer, a decrease of corneal thickness etc. They result in alterations of some of the biomechanical parameters of the cornea, namely, rigidity and elasticity. The present study was performed to examine how impression tonometry and applanation tonometry for determination of intraocular pressure (IOP) are affected by the changed biomechanical parameters associated with keratoconus. PATIENTS AND METHODS: We examined 20 normal subjects (40 eyes) and 17 keratoconus patients (25 eyes). The corneal thickness was measured by ultrasound pachymetry in the corneal center. In the keratoconus patients, an additional measurement was made at the conus peak. The corneal curvature was determined using the TMS keratoscope. The IOP measurements were made with the Schiötz tonometer (10 g). For comparison, additional IOP measurements in the corneal center and, in the keratoconus group, on the conus peak were made with the applanation tonometer. RESULTS: The normal subjects had a central corneal thickness of 548 +/- 30 microns, compared to 505 +/- 42 microns in the corneal center and 425 +/- 41 microns on the conus peak in keratoconus patients. The average corneal curvature was 43.3 +/- 1.8 D in the normal subjects and 47.8 +/- 4.1 D in keratoconus patients. Applanation tonometry produced results on 11.33 +/- 1.43 mm Hg in the normal group (corneal center) compared to values of 12.00 +/- 2.55 mm Hg (corneal center) and 7.30 +/- 1.95 mm Hg (conus peak) in the keratoconus cohort. The coefficient of rigidity was 0.0236 +/- 0.0026 microliter-1 in the normal subjects, compared to 0.0173 +/- 0.0050 microliter-1 in the keratoconus patients. CONCLUSION: The morphological changes associated with keratoconus may cause tonometry errors.
A case of both atrial and ventricular stimulation by the sense event marker during external chest wall stimulation of a DDDR pacemaker is reported. This unusual phenomenon might produce pacemaker-mediated tachycardia.
The aim of outpatient surgery is to reduce costs in the health service. However, the number of surgeons working in a surgical department is dependent upon the numbers of occupied beds. This creates an existential conflict in which, by reducing the occupancy of beds in order to take on more outpatient cases, surgeons are putting their own jobs on the line. Possible solutions are here discussed.
Explore the source record for details and available documents.
BACKGROUND: Radial Keratotomy is one of the most frequent refractive surgical procedures performed worldwide. It results in considerable alterations of the corneal structure. What does this mean for the mechanical properties of the cornea? METHODS: Intraocular pressure was increased via a 180 degrees tilt. Before and during this procedure, corneal topography was measured by photokeratoscopy. We examined 36 patients after RK and 25 controls who had not undergone any surgical procedure. RESULTS: The corneal center flattened by 0.523 +/- 0.054 dpt (p < 0.01) in the RK patients and by 0.187 +/- 0.045 dpt (p < 0.05) in the control group. CONCLUSION: Even several years after radial keratotomy, corneal stability is still decreased.
The authors analyzed the data of seven patients who had undergone open heart surgery because of pacemaker endocarditis in the past 4 years. Repeated surgical interventions on the pacemaker system were found to be the most common predisposing factors. Staphylococcus aureus and Staphylococcus epidermidis were the most common causative organisms. Two-dimensional echocardiography was important in the diagnosis of cases with atypical clinical picture and negative blood cultures. We concluded that: (1) any pacemaker patient with fever should be considered to have a pacemaker endocarditis; (2) all of these patients should be examined by two-dimensional echocardiography; and (3) the total removal of the infected hardware seems to be the only way to achieve complete recovery.
The influence of corneal hydration on the precision of plano lamellas and on the precision of lenticles modified with a "non-freeze" technique was studied in pig eyes. Ten pig eyes were dissected with a rotating lamellar microkeratome, and the discs were measured with a mechanical pachymeter. The hydration of the discs was measured in BSS and in dextran solution. A total of 160 corneal discs with different degrees of hydration were modified with a "non-freeze" technique on concave anf convex vacuum cylinders and measured with a photokeratoscope TMS. The discs increased in thickness within 3 h becoming 1.7 times as thick in BSS and 1.2 times as thick in dextran. After refractive dissection minor modifications were achieved with higher precision than were larger corrections. However, we achieved an undercorrection after all refractive dissections. Plano-discs for refractive modification should be taken from dehydrated corneoscleral discs or from intact eyes. Owing to mechanical factors during cutting and tissue hydration undercorrection of the intended change was observed.
Low-anticoagulant heparin (LA-heparin) obtained by affinity chromatography on antithrombin III Sepharose inhibits the proliferation of cultured arterial smooth muscle cells in an in vitro bioassay system as effectively as standard heparin. A growth inhibition of smooth muscle cells of about 60% is achieved when LA-heparin or heparin is added to the culture medium to a concentration of 50 micrograms/ml. In normolipemic rats LA-heparin suppresses the formation of neointimal thickenings and stenosis after balloon catheter-induced deendothelialization of the carotid artery. In terms of mass a dose of 5 mg/kg body weight/d given subcutaneously twice daily one week before and 2 weeks after balloon injury the cross sectional area of the neointima is reduced to 36% as compared with the nontreated control group (100%). This 64% reduction is statistically highly significant (p < 0.001). After treatment with 0.5 mg LA-heparin/kg/d the reduction of the neointima was 11% (p < 0.05). At a dose of 5 mg/kg body weight single or repeated administrations of LA-heparin caused only a small and transient increase in activated partial thromboplastin time values. The results show that subcutaneous administration of LA-heparin very effectively prevents smooth muscle cell proliferation and balloon catheter-induced neointimal growth. The well tolerated systemic application of this chemically non-modified LA-heparin might justify clinical trials for prevention of restenosis after percutaneous transluminal coronary angioplasty or other invasive cardiovascular interventions without complications of bleeding.
The aim of this study was to evaluate the long term results of atrial pacing. There were 27 atrial pacemaker implantations and 26 out of them were followed for an average of 47, 04 months. Lead dislodgement occurred in two cases, which made necessary a ventricular pacing. Three other patients developed chronic atrial fibrillation. The late results of the remaining 21 patients were very good. No AV-block occurred during the follow-up period. The atrial pacing in selected patients is safe and reliable, and financial restraints makes it advantageous for economic reason.
BACKGROUND: In an experimental study we examined the aerodynamical airstreamprofile of a new airstream aesthesiometer. With this instrument it is possible to measure corneal sensitivity without touching the cornea. METHOD: A constant hotwire-anemometer was used to measure the 0.5 s air impulse in different distances. The corneal topographic sensitivity was measured at 45 probands, age 20 to 80. RESULTS: The investigations show that the laminar air stream within the 0.2 mm wide nozzle changes after withdrawal, in regards to stream profile, jet width and speed. The parabolashaped stream profile passes over through the air matrix and changes into a bell-shaped profile. The stream properties of the circular free system imply that the air stream in a 4 mm distance is nearly half as wide and double as high or fast in comparison to an 8 mm distance. The corneal sensitivity measured with the CMA showed in comparison to the Draeger aesthesiometer a lower sensitivity than in the periphery. CONCLUSION: A clinical use for measuring corneal sensitivity with the CMA can not be recommended.
Corneal sensitivity was examined with the Draeger aesthesiometer in 8 patients after lamellar keratoplasty, 7 patients after epikeratophakia and 82 patients after photorefractive keratectomy. We examined 9 different points in each cornea. The corneal sensitivity of patients after lamellar keratoplasty was normal 1 year after operation. A correlation with the depth of the lamellar dissection was demonstrated. Patients with lamellar keratoplasty with pterygium showed a sensitivity decrease in the nasal parts of the lenticule even after one year. Three years after epikeratophakia the corneal center was still not sensitive. After photorefractive keratectomy of more than 10 D, corneal hyposensitivity was shown even 2 years after operation.
A new air aesthesiometer developed by S. Weinstein was tested with an anemometer device. It could be shown that the air stream is not linear. The normal sensitivity threshold pattern was measured in 271 probands varying in age from 10 to 98 years. In a comparative study we measured the corneal sensitivity of 20 patients after penetrating keratoplasty with the air aesthesiometer and the Draeger electromechanical aesthesiometer. Because of the aerodynamic broadening of the airstream it was not possible to measure corneal sensitivity at the transplant periphery or host cornea with the new device, while we could demonstrate corneal nerve fibre degeneration at the host cornea or regeneration of the transplant with the electromechanical aesthesiometer.