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Biomedical subjects

H Schüller

Publications and source records attributed to H Schüller.

At least 55 records · Page 3Linked to original sources
PubMed1993

[The maxillary sixth-year molar and its relation to the maxillary sinus. A comparative study between the panoramic tomogram and the computed tomogram].

Panoramic radiographs (OPGs) and computer tomograms (CTs) of 30 patients, the latter taken on average 2.5 months later, were evaluated for the purpose of comparing the relation of their roots to the bottom of the maxillary sinus. The CT and OPG images yielded significant differences in the topographic relations between the roots and the maxillary sinus. In the OPG 64 out of 129 roots seemed to penetrate the maxillary sinus. In the CT transversal slices, on the other hand, penetration could be observed for only 37 roots. This phenomenon became more apparent when the relations between the mesial, distal, buccal, and oral root surfaces and their relations to the sinus were assessed. Applying a three stage scoring scheme, it was found that in the large majority of cases only the apices were in contact with the mucosa of the sinus. Thus, the possible loss of anchorage in these cases is below five percent.

Adolescent↗
PubMed1993

[The value of high resolution computed tomography (HRCT) in the diagnosis of deep forms of parodontitis].

It is difficult to demonstrate the extent of parodontal bone erosions with conventional radiographic techniques. HRCT makes it possible to demonstrate the alveolar structures without superimposition. 10 patients with parodontitis marginalis profunda were examined by conventional methods and HRCT. Comparison showed considerable superiority of HRCT in respect of demonstrating bone destruction. The absence of superimposition produces excellent demonstration of the roots and shows the bifurcation and trifurcation of teeth; consequently, mapping the position and shape of the root canals is possible and this is an important aid in the planning of parodontal surgical treatment.

Adult↗
PubMed1993

[Metabolic studies of the calf musculature with 31P-MR spectroscopy in arterial obstructive disease before and after lumbar sympatholysis].

In 9 patients with arterial occlusive disease of grade IV according to Fontaine, energy metabolism was measured in the calf muscle during rest, before and after lumbar sympatholysis, by means of 31phosphorus MR spectroscopy. The concentration of inorganic phosphate (Pi) and phosphocreatine (PCr) relative to high energy phosphates, as well as the pH value in muscle cells were assessed, and the quotient Pi/PCr was calculated for estimation of energy reserves. Before sympatholysis, normal concentrations of the energy suppliers ATP and PCr were unexpectedly found in combination with reduced cellular energy reserves. After lumbar sympatholysis, in most cases no significant changes of muscle energy metabolism were detected. Independent of the muscle energy supply, a slight increase in energy supply without returning to normal values was found in only three patients. In most patients the clinical symptoms had improved at least to some extent.

Adult↗
PubMed1992

Natural history of sinus node disease treated with atrial pacing in 213 patients: implications for selection of stimulation mode.

OBJECTIVES: This study was designed to analyze the incidence and determinants of complications and long-term survival in sinus node disease treated with atrial pacing. BACKGROUND: Knowledge of the natural history of sinus node disease treated with different pacing modes is imperfect, and controversy exists regarding the optimal pacemaker therapy. METHODS: A consecutive series of 213 patients with sinus node disease initially treated with atrial pacing was studied for a median follow-up period of 60 months. The end points studied were permanent atrial fibrillation, high grade atrioventricular (AV) block, P wave undersensing, pacing mode change, reoperation and death. Several prognostic factors were evaluated statistically and the survival rate was compared with that of a matched general population. RESULTS: The incidence rate of permanent atrial fibrillation during follow-up was 7% (1.4%/year). The risk of this arrhythmia increased substantially with age greater than or equal to 70 years at pacemaker implantation. Only 2 of the 15 patients who developed permanent atrial fibrillation required ventricular pacing. High grade AV block occurred in 8.5% (1.8%/year) and its incidence was much greater in patients with complete bundle branch block or bifascicular block (35%) than in patients without such conduction disturbances (6%). A change to ventricular or dual-chamber stimulation was necessary in 14% of all patients, primarily because of early lead dislodgment or high grade AV block. Surgical intervention with maintenance of atrial pacing was required in 7% of patients. The survival rates of 97% at 1 year, 89% at 5 years and 72% at 10 years did not differ significantly from those of a matched general population. CONCLUSIONS: In sinus node disease, atrial pacing can be successfully applied during long-term follow-up. Patients with complete bundle branch or bifascicular block in addition to sinus node disease should initially receive a dual-chamber pacemaker, but routine application of dual-chamber stimulation does not appear to be warranted.

Adolescent↗
PubMed1992

[The radiation loading of the crystalline lens and thyroid during high-resolution computed tomography of the teeth].

The radiation dose to the ocular lens and thyroid gland during high resolution CT of the jaw was measured in a head phantom and in 9 patients. The dose for the lens and thyroid gland resulting from 10 cuts was 0.7 and 0.9 mGy, respectively. By shielding the thyroid gland against scatter a reduction of 20% is possible. Radiation exposure is considerably higher than during conventional dental x-ray examinations. Compared with CT examinations of the head and neck region, radiation exposure of both organs is about the same.

Humans↗
PubMed1992

[The results of the chemoembolization of advanced hepatocellular carcinomas. The effect on the survival times, morphological findings and tumor markers].

Chemoembolization is a well-recognized therapeutic procedure in the treatment of stage I and stage II hepatocellular carcinoma (HCC). Until now it is rarely used in the treatment of stage III HCC. In a prospective study we analysed the efficacy and the side effects of chemoembolization in 16 patients with stage III HCC. Chemoembolization was performed with an emulsion of lipiodol, 4-epirubicin and cisplatinum. All patients tolerated the treatment without remarkable complications. With 9 months the median survival rate was considerable higher than the survival rate of untreated patients and of patients treated with systemic chemotherapy or with local perfusion.

Aged↗
PubMed1992

[Damage to the remaining teeth from displaced upper canines].

25 patients with 35 retained upper canines were examined by high resolution CT; only 5 patients did not show evidence of damage to the remaining teeth. 8 patients showed resorption related to medial and lateral incisors. 19 teeth were in contact with the crowns of the displaced canines and were therefore liable to damage. The average extent of the resorption was 4.5 mm. Contact between teeth was demonstrable by means of two consecutive CT cuts.

Adolescent↗
PubMed1992

The application of computerized tomography (CT) in cases of impacted maxillary canines.

A comparison is made between conventional X-rays and computerized tomography (CT) based on eight patients with thirteen impacted upper permanent canines. The use of CT yields information which is much more detailed than that observed on conventional X-rays, such as: pathological resorption on adjacent teeth caused by aberrant canines; the localization of the injury and the position of the canine in relation to one or both incisors. The amount of radiation per exposure is still rather high for the CT (Köster and Ewen, 1986). Further research is necessary in order to reduce this exposure and to determine the appropriate and most effective use of CT in the dental field.

Adolescent↗
PubMed1991

The pacemaker syndrome: old and new causes.

The pacemaker syndrome refers to symptoms and signs in the pacemaker patient caused by inadequate timing of atrial and ventricular contractions. The lack of normal atrioventricular synchrony may result in decreased cardiac output and venous "cannon A waves." A sudden increase in atrial pressure at the onset of asynchrony may elicit a systemic hypotensive reflex response. A wide range of symptoms can be observed. The pacemaker syndrome is encountered in a significant number of patients with ventricular (VVI) pacemakers, mostly when 1:1 retrograde ventriculoatrial conduction is present. The risk of occurrence of the pacemaker syndrome is minimized if pacemaker systems are used which restore or maintain the normal atrioventricular contraction sequence. Hence, in sinus node disease, atrial stimulation with or without ventricular stimulation should be employed, while in high-grade atrioventricular block dual-chamber pacing is recommended. The pacemaker syndrome is not restricted to the VVI stimulation mode. It can be seen, though rarely, in atrial and dual-chamber pacing, and an awareness of these new causes is necessary. An established pacemaker syndrome can often be counteracted by adjusting the pulse generator function.

Electrocardiography↗
PubMed1991

Practical aspects of rate adaptive atrial (AAI,R) pacing: clinical experiences in 44 patients.

Forty-four patients with sinus node disease and chronotropic incompetence but no evidence of AV conduction disturbances were treated with rate adaptive atrial (AAI,R) pacemakers. Medtronic Activitrax and Siemens Sensolog activity sensing single chamber pulse generators were used. Twenty-four patients (55%) had the bradycardia-tachycardia syndrome. The mean follow-up time is 20 +/- 14 months (range 1-48, median 17 months). All patients remain alive. Two patients were reoperated upon for lead problems without change of pacing mode. One patient developed symptomatic second-degree Wenckebach block during follow-up, and received a DDD,R system. Although 22 of the patients were treated with antiarrhythmic drugs postoperatively, no further cases of significant AV conduction disturbances were seen. During rapid atrial pacing, exercise-induced enhancement of AV conduction was a consistent finding, although less pronounced in patients treated with beta-blocking drugs. One patient developed permanent atrial fibrillation with an adequate ventricular rate. By systematic reprogramming procedures, QRS complex sensing through the atrial electrode could be demonstrated in 25 patients (23/28 with unipolar and 2/16 with bipolar leads). It could be counteracted effectively by pulse generator program selection in all cases. Forty-two of 44 patients (95%) remain in AAI,R pacing with normal function. Rate adaptive atrial pacing can be successfully applied in this patient group.

Adolescent↗
PubMed1990

Atrial rate-responsive pacing in sinus node disease.

Patients with sinus node disease (SND) who are unable to achieve an adequate increase in heart rate during exercise are candidates for atrial rate-responsive pacing (AAI-R). We have implanted 40 AAI-R systems in SND patients with an average follow-up of 12.5 +/- 8 (range 3-30) months. All the patients received an activity-sensing pulse generator (Activitrax, Medtronic or Sensolog, Siemens-Pacesetter) with a single atrial lead. Only patients with an intraoperative AV nodal block cycle-length above 100 beats min-1 were included. During follow-up, one patient was observed to have transient asymptomatic 2:1 AV-block during sleep. No patient developed persistent AV-block or chronic atrial fibrillation. Twelve patients with persistent chronotropic incompetence were assigned for a randomized double-blind crossover study, comparing exercise treadmill capacity in AAI-R with conventional atrial inhibited pacing (AAI). During AAI-R pacing the maximum heart rate during exercise was 120 +/- 1 beats min-1 compared with 97 +/- 21 beats min-1 during AAI pacing (P less than 0.01). The average exercise time increased from 11.2 +/- 2 min during AAI-pacing to 13.4 +/- 3 min during AAI-R pacing (P less than 0.01). AAI pacing should be considered for patients with SND and chronotropic incompetence.

Cardiac Pacing, Artificial↗
PubMed1990

Acute atrial endocardial P wave amplitude and chronic pacemaker sensitivity requirements: relation to patient age and presence of sinus node disease.

Data are reviewed from 88 patients who received double, passive-fixation unipolar endocardial leads for DDD pacemaker treatment. Identical electrodes were used in the right atrium and the right ventricle. Intra-atrial P wave amplitudes, intraventricular QRS complex amplitudes, and atrial and ventricular pacing thresholds were determined at implantation. The intra-atrial P wave amplitudes were not significantly correlated to the intraventricular QRS complex amplitudes. No significant correlation was found between the atrial stimulation thresholds and the ventricular pacing thresholds. The intra-atrial P wave amplitude showed a significant inverse and logarithmic correlation with patient age (P = 0.007). Furthermore, patients with sinus node disease had significantly lower intra-atrial P wave amplitudes (P = 0.04) than patients without this abnormality. The acute atrial and ventricular pacing thresholds and the intraventricular QRS complex amplitude were not correlated to patient age or presence of sinus node disease. Patients requiring higher atrial amplifier sensitivity settings during follow-up were significantly older (P less than 0.05) than those in whom lower atrial sensitivities were sufficient. A postoperative attenuation of the atrial electrogram was detectable by sensitivity programming procedures in 29 of the patients (35%). This phenomenon did not significantly relate to patient age or presence of sinus node disease. No case of permanent atrial undersensing occurred. It is suggested that the lower intra-atrial P wave amplitudes in older patients and patients with sinus node disease reflect degenerative changes in the atrial myocardium. The statistical relations found appear to motivate special attention to atrial sensing in these patient groups.

Adolescent↗
PubMed1990

Atrial and ventricular stimulation threshold development: a comparative study in patients with a DDD pacemaker and two identical carbon-tip leads.

The atrial and ventricular pacing threshold development during the first postoperative year was studied in a group of patients receiving DDD pacemakers. Identical carbon-tip endocardial leads were implanted in atrium and ventricle. Atrial and ventricular voltage stimulation thresholds were measured at implantation, and noninvasively at 1 and 12 months thereafter. The atrial amplifier sensitivity required for adequate P wave sensing during follow-up was also determined. The possible influence of a number of factors upon atrial and ventricular threshold evolution was statistically assessed. The threshold data were complete in 57 patients (mean age +/- SD, 65.2 +/- 12.4 years). Thirteen patients had a diagnosis of sinus node disease, whereas 44 had not. Patient age and diagnosis did not significantly influence atrial or ventricular stimulation threshold development. Atrial sensing thresholds were not related to atrial stimulation thresholds during follow-up. Atrial pacing thresholds were higher than ventricular thresholds at pacemaker implantation (P less than 0.00005), but the postoperative threshold rise and thresholds at 1 and 12 months postoperatively did not differ significantly between the atrium and ventricle. The ratio of chronic to acute stimulation thresholds was higher on the ventricular than on the atrial level (0.001 greater than P greater than 0.0005). The chronic atrial threshold showed a logarithmic relation to the threshold at implantation (P = 0.0006); postoperative threshold rise was not a significant determinant of the chronic atrial threshold (P = NS). On the ventricular level, the reverse was seen: The chronic threshold was related to the postoperative threshold rise (P = 0.0015, logarithmic relation), but not to the implantation threshold (P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

[Malignant skin and soft tissue tumors--diagnostic imaging].

Clinical evaluation of the definite size and extension of malignant skin- and soft tissue tumors is limited. Ultrasound provides a first orientation of tumor size and differentiates between solid and cystic lesions. Conventional Radiographs prove or rule out bone or periostial involvement and endotumoral calcification. If further diagnostic workup is needed MRI is the method of choice for defining the exact tumor topography, size and the affected compartments as well as the involvement of cancellous bone and bone marrow.

Diagnostic Imaging↗
PubMed1988

Isochromosomes i(8q) or i(9q) in three adenocarcinomas of the lung.

We have cytogenetically analyzed three primary adenocarcinomas of the lung. All tumors had chromosome numbers in the triploid region. The multiple structural aberrations included rearrangements of 3p, in two cases affecting the segment 3p14-23, where deletions are characteristically found in small cell lung carcinomas. Isochromosomes for 8q were present in two tumors and i(9q) in one tumor. In the few previously reported cytogenetic analyses of pulmonary adenocarcinomas, all of which examined metastases or cell lines, i(8q) was found in one case and i(9q) in two cases. These isochromosomes, therefore, represent previously unrecognized nonrandom changes in adenocarcinomas of the lung, and might constitute primary aberrations in this tumor type.

Adenocarcinoma↗
PubMed1988

Long-term pacing in sinus node disease: effects of stimulation mode on cardiovascular morbidity and mortality.

In a previous retrospective treatment-comparison study of 168 patients with sinus node disease, we found a significantly higher incidence of permanent atrial fibrillation and congestive heart failure in patients treated with ventricular (VVI) pacing compared to atrial (AAI) pacing, after an average follow-up period of 2 years. To determine whether these differences persisted and whether AAI pacing resulted in a lower mortality rate than VVI pacing during long-term follow-up, the treatment groups were restudied after an average of 4 years of pacemaker treatment. The incidence of permanent atrial fibrillation was still significantly higher (p less than 0.0005) in the VVI group than in the AAI group after the additional 2 years (VVI = 47%, an increase from 29%; AAI = 6.7%, an increase from 3.4%). Congestive heart failure occurred significantly more often in the VVI group than in the AAI group (37% vs 15%, p less than 0.005). Analysis of survival data showed a higher overall mortality rate in the VVI group (23% vs 8%, p less than 0.05). The development of high-degree atrioventricular block in the AAI group remained low (total 4.5%). Thus, in sinus node disease, the advantages of AAI over VVI pacing persist during long-term follow-up. The differences in cardiovascular morbidity between the groups tend to increase with time and appear to result in a lower mortality rate among patients treated with AAI pacing.

Actuarial Analysis↗