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Biomedical subjects

B Lüderitz

Publications and source records attributed to B Lüderitz.

At least 271 records · Page 15Linked to original sources
PubMed1994

[The value of magnesium in intensive care medicine].

UNLABELLED: In the management of severely ill patients it has been suggested that magnesium might protect the heart muscle and prevent lift-threatening irregularities of heart rhythm. 1) Cardiac arrhythmias: The mechanism of action of magnesium in monomorphic ventricular tachycardia is not known. Magnesium does not affect the effective refractory period of ventricular structures. It alters the inward rectifying potassium channel in experimental animal models. Though magnesium may exhibit negative inotropic effects in animal studies, an increase of the cardiac index during ventricular tachycardia could be documented in recent investigations. The application of magnesium is usually well tolerated. Magnesium (i.v.) is indicated in Torsade de pointes tachycardia Digitalis-induced cardiac arrhythmias Monomorphic ventricular tachycardia (efficacy ca. 30%) Multifocal atrial tachyarrhythmias. 2) Myocardial infarction: In the past, several trials of intravenous infusions of magnesium have indicated a considerable mortality reduction following myocardial infarction. More recently, the LIMIT-2 (Leicester Intravenous Magnesium Intervention Trial) of a 24-h magnesium infusion in about 2000 patients indicated a benefit of about 25%. Now, the ISIS-4 (International Study of Infarct Survival)-trial has tested magnesium in 58,000 patients. In ISIS-4 there was no evidence of a beneficial effect of magnesium on mortality--neither in all patients nor in any particular type of patient. Overall, there was no beneficial effect on morbidity. According to these data, there seems only a limited role for magnesium in the routine treatment of cardiac infarction patients. IN CONCLUSION: Intravenous magnesium can terminate Torsade de pointes tachycardia and, in selected patients, monomorphic ventricular tachycardia regardless of the serum magnesium concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Arrhythmia Agents↗
PubMed1994

[The effect of the impulse form of the defibrillation shock on its effectiveness and device technology of the implantable cardiac defibrillator].

Efforts have been focussed on the development of implantable cardioverter-defibrillator systems that reduce the size of the devices, simplify the methods of electrode implantation, and increase device longevity. The size of implantable units is predominantly determined by the capacitors and batteries, and this is dependent on the output energy requirements. The energy required for defibrillation and therefore the size of the devices can be reduced by utilizing optimal lead systems and waveforms. This report describes our experience with various shock waveforms in 86 consecutive patients undergoing implantation of a cardioverter-defibrillator with a nonthoracotomy approach. Table 1 provides information on the demographic characteristics of the study population, the various shock waveforms and lead configurations tested. In 20 patients, a bidirectional lead configuration was tested using simultaneous and sequential monophasic waveforms. In 18 patients, simultaneous monophasic and biphasic waveforms with a fixed pulse duration of 6.3 ms were employed utilizing a bidirectional lead system. In 31 patients, a undirectional lead configuration was used, and simultaneous monophasic and biphasic shocks with a constant tilt were delivered. In 17 patients, the defibrillation efficacy of biphasic and triphasic shock waveforms with a fixed pulse duration of 10 ms was evaluated. The study design was an open, randomized and prospective evaluation in all patients. Defibrillation threshold was determined in a randomized sequence using a step down protocol. The defibrillation threshold was defined as the lowest energy required for effective defibrillation on two occasions. In the 20 patients using a bidirectional lead configuration, there was no significant difference in defibrillation energy requirements between simultaneous and sequential monophasic shock waveforms.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Polycystic and cavernous course of pneumocystis carinii pneumonia in AIDS].

We observed a polycystic and cavitating presentation of Pneumocystis carinii pneumonia as primary manifestation of AIDS in a patient with previously unknown HIV-infection. Pneumocystis carinii was histologically proved by transbronchial biopsy but not by bronchoalveolar lavage. A nearly complete resolution of all pulmonary lesions could be achieved with cotrimoxazole. Pneumocystis carinii must be considered in differential diagnosis of cystic and cavitating pulmonary disease in patients with unknown or positive serology for HIV-infection.

AIDS-Related Opportunistic Infections↗
PubMed1994

Echocardiographic profile of the normally functioning Omnicarbon valve.

Transthoracic echocardiography was performed in 141 patients with 90 Omnicarbon valves in the aortic and 66 in the mitral position. Additionally, 53 of them were investigated by transesophageal echocardiography comparing monoplane and multiplane facilities. The opening direction of the disc and the location of the pivot axis could be correctly determined by transthoracic, monoplane, and multiplane transesophageal echocardiography, respectively, in 100%, 80%, and 100% of the mitral and in 53%, 21%, and 82% of the aortic prostheses. Small regurgitation jets were detected in 90% of the aortic valves (1.6 +/- 0.4 cm2) by transthoracic and in all mitral prostheses (2.3 +/- 0.8 cm2) by transesophageal echocardiography. Based on morphological identification of the pivot points structures, origins of leakage jets were clearly identified as "design-related" in 12% (transthoracic echocardiography of aortic valves) to 100% (multiplane transesophageal echocardiography of mitral valves). In the aortic position, values obtained for transprosthetic forward flow velocity measurements exhibited wide scatter which did not allow a firm separation between valve sizes. No better differentiation was possible by using the calculated Doppler gradients or the velocity time integrals, either. Mean gradients and velocity time integrals showed even smaller differences between groups in the mitral valve patients. It is concluded that the Omnicarbon valve has a suitable design for morphological echocardiographic examination, and multiplane transesophageal technique expands the diagnostic capability. Forward flow measurements do not appear to be suited for detecting a beginning obstruction of this mechanical prosthesis.

Adult↗
PubMed1994

[Effect of nisoldipine and diltiazem on systolic and diastolic function of the left ventricle in patients with coronary heart disease].

OBJECTIVES AND BACKGROUND: Calcium channel blockers have a negative inotropic effect and protract the relaxation of the normal myocardium. These effects may vary in patients with coronary artery disease (CAD) and with the different kinds of calcium antagonists. In the present study we therefore compared the hemodynamic effects of intravenously given equihypotensive dosages of diltiazem (D) and nisoldipine (N) in patients with CAD. METHODS AND RESULTS: Each group contained 10 patients. After administration of a bolus of 300 micrograms/kg (D) and 5 micrograms/kg (N) respectively and following continuous infusion of 5.4 micrograms/kg/min (D) and 0.2 micrograms/kg/min (N) respectively, the mean arterial pressure was reduced by 15.5 +/- 6.0 (D) and 16.6 +/- 4.1 (N) mm Hg. Atrial pacing was performed in all patients to avoid reflectory heart rate effects. The pulmonary artery pressure decreased slightly with both drugs, whereas the cardiac index increased only with the use of N from 3.44 l/min x m2 to 3.93 l/min x m2. A significant change in the maximal rate of rise of left ventricular pressure (dP/dt max) as an index for inotropy was not detected for N or for D. The parameters of the diastolic function (the time constant of ventricular relaxation (tau) and the maximum rate of left ventricular isovolumic pressure decline (dP/dt min)) also did not indicate unequivocal drug effects. Doppler echocardiography of the mitral valve flow was performed simultaneously with invasive pressure measurements. The flow propagation derived from the color-M-mode correlated significantly with tau and was slightly improved by D.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

[Adenosine in prediction of the success of radiofrequency ablation in Wolff-Parkinson-White syndrome].

Rapid bolus injection of adenosine has been shown to produce transient atrioventricular (AV) nodal block while having almost no direct effect on accessory pathway conduction. The aim of this study was to determine the efficacy of adenosine for prediction of success of catheter ablation in WPW syndrome in 31 patients (23 with preexcitation; 8 with concealed conduction) before and 30 min, 5-7 days, and 3-6 months after attempted radiofrequency catheter ablation. Before ablation 6 mg adenosine produced maximal preexcitation (QRS duration increased from 100 +/- 15 ms to 123 +/- 18 ms) in patients with manifest preexcitation, while AV block occurred in all patients (100%) with concealed conduction for 1.5 +/- 0.5 s. No patient had accessory pathway conduction unmasked by adenosine. In 30/31 (96%) of patients retrograde conduction was unchanged prior to ablation. Immediately after ablation adenosine induced AV and VA block in 29 (93%) patients. These results were also present 5-7 days and 3 months later and were confirmed by electrophysiologic study. The positive and negative predictive values are 96% and 100%, respectively. Adenosine is reliable and useful to predict short- and long-term success following radiofrequency catheter ablation.

Adenosine↗
PubMed1993

[Radiofrequency ablation of accessory pathways in pre-excitation syndrome].

Various parameters relating to the radio-frequency ablation of accessory pathways were studied in 53 patients (27 males, 26 females: mean age 38.5 [14-64] years) with a history of paroxysmal tachycardia (over 1 month to 50 years), shown to be caused by an accessory pathway (Wolff-Parkinson-White syndrome). In all patients the following values were obtained: (1) number of procedures necessary to achieve permanent blockage of the accessory pathway (1-4); (2) duration of each procedure (45-420 min); (3) duration of fluoroscopy (5-102 min); (4) number of necessary radio-frequency applications (1-48); and (5) cumulative energy per procedure. To ablate left-lateral pathways (n = 10) required fewer procedures, shorter duration per procedure, shorter fluoroscopy time, fewer current applications and less total energy than coagulation of right-sided pathways (n = 10). Those various parameters were greatest for ablation of septal and para-septal pathways (n = 9). Pathways which conducted only retrogradely (n = 15) were more difficult to ablate than those with anterograde conduction (n = 38). There were two complications. In one case a tension pneumothorax occurred after faulty puncture of the subclavian vein; in the other, the left ventricle was perforated causing an acute tamponade which required pericardiocentesis with subsequent suture closure of the perforation. It is concluded that, in principle, all accessory pathways, regardless of their conduction potential and site, can be ablated by a radio-frequency current.

Adolescent↗
PubMed1993

[The quality of life after the implantation of a cardioverter/defibrillator in malignant arrhythmias].

Quality of life after implantation of an automatic implantable cardioverter/defibrillator (ICD) was assessed by questionnaire in 43 patients (38 males, 5 females; mean age 57 +/- 16 years) with treatment-resistant symptomatic ventricular arrhythmias. 37 of the 43 patients felt better after ICD implantation. 23 were always conscious of having an ICD, but 18 had got used to it in less than 2 months. 15 patients reported being afraid of an ICD shock, while eight noted physical discomfort caused by the ICD. Limitations concerning their professional, recreational and social activities were reported by six patients. 41 of the 43 patients confirmed that the ICD had been helpful, enabling 23 to return to an active life. 42 would recommend implantation to others if indicated. These data demonstrate that there is a remarkably high degree of acceptance of the ICD. Survival rate after implantation is thus not the only criterion of success. All aspects of the quality of life should be taken into consideration before implantation is decided upon.

Adult↗
PubMed1993

Supraventricular tachycardia and pre-excitation syndromes: pharmacological therapy.

Tachyarrhythmias which originate above the bifurcation of the bundle of His or incorporate tissue proximal to it are classified as supraventricular tachyarrhythmias (SVT). Primary treatment of SVT attempts to influence the underlying disease. Therapy is subdivided into drug therapy, electrotherapeutic tools (e.g. antitachycardia pacemakers, catheter ablation) and antiarrhythmic surgery. Antiarrhythmic agents which slow conduction and suppress premature beats are efficient for emergency and long-term treatment of supraventricular tachycardias. We evaluated some of the most relevant antiarrhythmic drugs for SVT including propafenone, diprafenone, cibenzoline, lorcainide and sotalol; in addition, usage and efficacy of quinidine/verapamil, disopyramide, amiodarone, ajmaline, adenosine and flecainide are summarized. The principles for acute management of tachycardia episodes with narrow and broad complexes are outlined. The reason for the selection as well as the efficacy in the termination of the tachycardias is described for different antiarrhythmic agents including verapamil, adenosine, ajmaline, propafenone and flecainide.

Ajmaline↗
PubMed1993

Effects of antiarrhythmic drugs on epicardial defibrillation energy requirements and the rate of defibrillator discharges.

Antiarrhythmic drugs are commonly used with the implantable cardioverter/defibrillator to treat recurrent ventricular tachyarrhythmias. Since various antiarrhythmic drugs have been reported to alter defibrillation threshold, an important question is whether the device will provide adequate energy for defibrillation during long-term follow-up and to what extent antiarrhythmic drug treatment will affect defibrillation energy requirements. To answer these questions, the defibrillation thresholds were determined in 20 patients using an epicardial patch-patch lead configuration at the time of implantation and at the time of pulse generator replacement. During a mean follow-up period of 24 +/- 6 months, the defibrillation threshold increased significantly from 14.2 +/- 3.7 joules to 18.3 +/- 5.5 joules in the entire group (P < 0.05). This increase in defibrillation threshold was due to a marked elevation of defibrillation energy requirements in the subgroup of patients taking amiodarone compared with patients receiving mexiletine. Based on these results it is mandatory to retest defibrillation threshold at any time of pulse generator replacement to guarantee continued effectiveness. In particular, if amiodarone treatment is initiated after implantation of a defibrillator, it is recommended to reevaluate defibrillation threshold to ensure an adequate margin of safety.

Amiodarone↗
PubMed1993

Efficacy and safety of combination therapy with amiodarone and type I agents for treatment of inducible ventricular tachycardia.

In a prospective study the efficacy of amiodarone in combination with the three Class I drugs mexiletine, flecainide, or encainide was evaluated consecutively in 12 patients with recurrent ventricular tachycardias (VT) by programmed stimulation. None of the tested drug combinations suppressed induction of sustained VT. The combination of amiodarone with Class IC drugs flecainide and encainide prolonged the cycle length of VT significantly, whereas the combination with mexiletine did not have the same degree of slowing on the VT cycle length. Several proarrhythmic effects occurred during the combination therapy with encainide: (1) frequent, spontaneous recurrences of hemodynamically well tolerated VT in four patients; (2) enhanced inducibility of VT in three patients; (3) impaired termination of VT in three patients. Though a marked increase in QRS and QTc intervals was observed by combined treatment with encainide, no significant correlation could be established between aggravation of arrhythmia and plasma levels of encainide, degree of QRS widening, JT or QTc prolongation. The only predictor for the occurrence of proarrhythmic events was found in left ventricular ejection fraction. These findings suggest that in patients refractory to amiodarone alone or a combination with mexiletine, the combined treatment of amiodarone with other Class IC drugs prolongs the VT cycle length but does not suppress induction of VT during programmed stimulation. Combination therapy of amiodarone with encainide was associated with a high incidence of proarrhythmic effects.

Adult↗
PubMed1993

Patient acceptance of the implantable cardioverter defibrillator in ventricular tachyarrhythmias.

Besides surgical problems, recipients of implantable cardioverter defibrillators (ICDs) are faced with psychological and social adjustments. Successful ICD therapy is influenced by the patients' perceived concerns regarding device, discharge, changes in life style, and complications. In order to assess patients' acceptance of the ICD, the psychological profile of 57 consecutive patients was evaluated using a specifically designed questionnaire and the State Trait Anxiety Inventory (STAI). The results showed that 20 patients stated fear of ICD discharge, 12 patients revealed physical discomfort due to the device, and limited quality-of-life occurred in 8 patients. Fifty-five of 57 patients answered that it was worth having an ICD device implanted, 30 (53%) patients returned to active life, and 56 (98%) would advise another patient to undergo implantation if necessary. Overall, there was only a slight, but insignificant, decrease in the level of anxiety within the total patient population after ICD implantation. However, a comparison of two subgroups indicated that the state of anxiety was significantly higher in patients < 50 years of age as well as in patients having received > 5 shocks versus those > 50 years of age and having experienced < 5 shocks. In general, the acceptance of the ICD as a tool in managing life-threatening ventricular tachyarrhythmias is high. Besides the increased survival rate, quality-of-life and patient acceptance are important criteria for successful ICD therapy.

Activities of Daily Living↗
PubMed1993

Mechanical dilatation rather than plaque removal as major mechanism of transluminal coronary extraction atherectomy.

Atherectomy with the transluminal extraction endarterectomy catheter (TEC) is a new approach for treatment of coronary artery disease, which continues to undergo FDA investigational studies. The major mechanism of the TEC device should be excision of plaque and its removal due to suction applied through an attached vacuum. We report about the acute results in 24 patients treated with TEC atherectomy in native vessels and the outcome of 18 patients who, until recently, underwent follow-up catheterization after 6 months. The procedure was successful (residual stenosis less than 50%) in 7 of 24 patients with TEC atherectomy alone (29%); 15 of 24 patients (65%) required additional PTCA in order to achieve angiographic success (10 of 24) or to treat total occlusion (2 of 24) or distal embolization (3 of 24) following atherectomy. One TEC attempt failed due to guiding catheter problems, another major complication was a vessel perforation leading to a non-Q wave infarction. The minimal residual diameter after passage of the stenosis (prior to additional PTCA) with the 5.5 Fr catheter (n = 14) was 1.5 +/- 0.2 mm, with the 6 Fr catheter (n = 9) 1.8 +/- 0.4 mm, and 2.2 +/- 0.2 mm using the 7 Fr catheter (n = 10). The histologic findings revealed intimal cells, fibrous tissue, and homogenate with no identifiable tissue in five cases (21%), whereas in 17 patients (72%) light microscopy could only assess blood cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗