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Biomedical subjects

B Waldecker

Publications and source records attributed to B Waldecker.

At least 37 records · Page 2Linked to original sources
PubMed1989

[Continuous ventricular tachyarrhythmia in patients without detectable organic heart disease: clinical and electrophysiologic findings].

In 22 of 335 consecutive patients (6.6%) referred for evaluation and treatment of sustained ventricular tachyarrhythmias, hemodynamic and angiographic findings revealed no structural heart disease. Entry arrhythmia was ventricular fibrillation in 10 patients and sustained ventricular tachycardia in 12 patients. A subgroup of four young patients presented with slow recurrent (during 51 +/- 43 months) sustained ventricular tachycardias that were reproducibly terminated by intravenous application of verapamil. Programmed ventricular stimulation replicated the clinical arrhythmia in nine patients (75%) with ventricular tachycardia. In five patients (50%) with ventricular fibrillation no sustained ventricular arrhythmia could be induced, and only with three extrastimuli in four of the remaining five patients. On hospital discharge, 14 patients received type III antiarrhythmic agents, five patients received type I agents, and one patient received verapamil. Two patients were discharged without medical therapy. During the following 24 +/- 9 months, four patients had recurrent sustained ventricular tachycardia. No patient died suddenly during follow-up. We conclude that about 6% of all patients with ventricular tachyarrhythmias have apparently normal hearts. These idiopathic tachyarrhythmias seem to have a benign course, at least when treated. Slow, verapamil-sensitive tachycardias of young people may represent a unique entity.

Adolescent↗
PubMed1989

[Long-term results of pacemaker therapy in hypersensitive carotid sinus syndrome].

131 patients received permanent pacemakers to treat their hypersensitive carotis sinus syndrome (HCSS). Prior to implantation, HCSS was diagnosed whenever spontaneous episodes of faintness or dizziness (n = 25) or syncope (n = 106) coincided with an abnormal response to carotis sinus massage (asystole greater than 3 s). 123 patients were followed for 48 +/- 27 months after implantation to assess the value of pacemaker therapy. 77% of all patients were free of initial symptoms. 90% of patients with syncope prior to pacemaker therapy were free of recurrence. Therefore, permanent pacing appears to be the treatment of choice for these patients. Since carotis sinus massage produced high-degree AV-block in at least 33% of patients, ventricular (rather than exclusive atrial) pacing seems to be mandatory. However, syncope did recur in 10% despite normal pacemaker function. The etiology of these recurrences remained unclear in almost all patients. As opposed to patients with syncope, cardiac pacing prevented symptoms in only 26% of patients with faintness or dizziness without full syncope. In these patients primary and sole pacemaker therapy does not appear to be appropriate.

Aged↗
PubMed1987

Programmed electrical stimulation in healed myocardial infarction using a standardized ventricular stimulation protocol.

The diagnostic accuracy of programmed electrical stimulation was prospectively assessed in 111 patients with myocardial infarction (MI) with or without a history of spontaneous ventricular arrhythmias. In 29 patients neither ventricular tachycardia (VT) nor episodes of 10 premature ventricular depolarizations per hour was documented. Fifty patients had documented nonsustained VT and 32 had sustained monomorphic VT. One and 2 extrastimuli (twice diastolic threshold, 2 ms in duration) were given during sinus rhythm and ventricular pacing at 100, 120 and 140 beats/min in the right ventricular apex (part I). When this protocol failed to induce a sustained monomorphic VT, a third extrastimulus was introduced (part II). Repetitive ventricular responses were induced in all patients, and in 15 (14%) polymorphic ventricular arrhythmias requiring DC shock were induced. Incidence of initiation of sustained monomorphic VT and polymorphic ventricular arrhythmias requiring DC shock was related to the clinical arrhythmia and the stimulation protocol. In patients with documented sustained monomorphic VT, a third extrastimulus only increased the incidence of sustained monomorphic VT (68% to 94%), whereas in patients with documented nonsustained VT and without VT the incidence of both polymorphic and monomorphic arrhythmias increased by 7 to 12%. Sustained monomorphic VTs induced in patients without such a history were faster (p less than 0.01), depended on site of MI (p less than 0.05) and were more often preceded by nonsustained polymorphic VT (p less than 0.01) than in patients with documented sustained monomorphic VT.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Amiodarone in patients with recurrent sustained ventricular tachyarrhythmias: results of programmed electrical stimulation and long-term clinical outcome in chronic treatment.

Thirty-three patients with clinically recurrent ventricular tachyarrhythmias were treated with amiodarone (200 to 600 mg/day) during a mean follow-up period of 23.7 months. Prior to amiodarone therapy, sustained ventricular tachycardia or ventricular fibrillation was initiated in all patients at control electrophysiologic study; patients failed a mean of 5.7 drugs, as assessed by programmed electrical stimulation. At electrophysiologic study after a loading phase (1000 mg/day for 10 days), 10 patients had no inducible ventricular tachycardia, nine patients had nonsustained ventricular tachycardia, 13 patients had persistent sustained ventricular tachycardia, and one patient had ventricular fibrillation. Patients were continued on amiodarone alone regardless of the findings at the electrophysiologic study, and during follow-up patients with no inducible sustained ventricular tachycardia or fibrillation on amiodarone had no recurrent arrhythmias or sudden death. Six of 14 patients (43%) with sustained ventricular tachyarrhythmias still inducible had recurrent ventricular tachycardia/fibrillation, and four of them died suddenly (29%). Programmed electrical stimulation predicts a good clinical long-term outcome during amiodarone therapy. Patients with persisting fast tachyarrhythmias (cycle length less than or equal to 300 msec) on amiodarone and a low ejection fraction (less than 35%) seem to have a higher incidence of sudden death. In these patients, therapeutic approaches such as antiarrhythmic surgery or implantation of antitachycardia devices should be considered.

Amiodarone↗
PubMed1986

Electrophysiologic characteristics of ventricular tachycardia or fibrillation in relation to age of myocardial infarction.

Evaluation of ventricular myocardium after the onset of acute myocardial infarction (AMI) suggests that the substrate for ventricular arrhythmias changes as the substrate for ventricular arrhythmias changes as the AMI heals. To determine if the ability of programmed stimulation to initiate ventricular tachycardia (VT) varies according to the interval between AMI and electrophysiologic testing, the clinical and electrophysiologic data of 42 patients with spontaneous sustained VT and 12 patients with ventricular fibrillation (VF) more than 3 days after a single AMI were analyzed. For patients with VT, there were no significant differences in the incidence of initiation of sustained monomorphic VT among those evaluated 1 to 3 weeks (100%), 3 to 8 weeks (75%), 2 to 6 months (100%), 6 to 18 months (80%) or more than 18 months (81%) after AMI, and the mean number of extrastimuli required for initiation did not differ among the groups. Patients evaluated more than 4 weeks after the initial episode of VT had a lower incidence of inducible VT than those studied earlier (14 of 21 [71%] vs 21 of 21 [100%], p less than 0.05), although this appeared to be a result of earlier termination of the stimulation protocol owing to initiation of polymorphic arrhythmias in those studied later. The 14 patients evaluated within 8 weeks of AMI had significantly faster VT rates (mean cycle length 269 +/- 45 ms) than the 28 patients studied later (320 +/- 75 ms, p less than 0.01), possibly because of more out-of-hospital presentations of VT in patients studied later.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

Dysrhythmias after direct-current cardioversion.

The success rate of direct-current (DC) countershocks and postshock arrhythmias are of concern for the design of automatic devices. Results of 112 DC shocks for induced ventricular tachycardia/fibrillation (VT/VF) (n = 99) or atrial fibrillation (AF) were analyzed. Clinical and arrhythmia characteristics were related to the success rate of DC shocks as well as postshock arrhythmias. Sixty-one patients were men and 14 were women; mean age was 52 +/- 15 years. Coronary artery disease was present in 56 patients and cardiomyopathy in 4. The other patients had no apparent structural heart disease. The success rate of transchest DC shocks for VT and VF were identical. The first DC shock interrupted 80% of VT and VF episodes. All episodes were terminated by 4 or fewer DC shocks. A single DC shock changed morphologic pattern or rate of 4 episodes of VT. Asystole after VT/VF (1,900 +/- 960 ms) was longer than after atrial fibrillation (1,150 +/- 470 ms, p less than 0.01). VT/VF recurred (within 3 minutes) after 26 of 99 initially successful DC shocks, requiring repeat shocks in 2 cases. Sinus bradycardia (n = 18) or high degree atrioventricular block (n = 11) necessitated rate support pacing in 10 patients. Antiarrhythmic drugs did not prevent postshock tachycardias, but facilitated the development of bradycardias. In conclusion, reliable and continuous analysis of cardiac rhythm after discharge is mandatory to enable automatic devices to correct unsuccessful discharges or recurring VT/VF. In addition, demand pacing capability is desirable to prevent severe bradycardia after DC shocks in patients receiving antiarrhythmic drugs.

Adult↗
PubMed1986

Importance of modes of electrical termination of ventricular tachycardia for the selection of implantable antitachycardia devices.

Different implantable systems for electrical treatment of ventricular arrhythmias are available. Information about mode of termination of ventricular tachycardia (VT) helps to select the most appropriate electrical treatment for drug-resistant VT. During 158 electrophysiologic studies, the mode of termination of 215 episodes of VT was analyzed in 2 groups of patients. Group 1 consisted of 54 patients with documented monomorphic VT and group 2 of 46 patients with other documented or suspected ventricular arrhythmias. Eighty-two patients had coronary heart disease, 8 had other structural heart disease and 10 had idiopathic VT. Termination of VT was attempted using extrastimuli and overdrive pacing; direct-current (DC) shocks were given in case of syncopal VT. During 33 of 96 studies (34%) in group 1, DC shock was required to interrupt VT, compared with 45 of 62 studies (73%) in group 2 (p less than 0.001). This difference was a result of less frequent induction of immediately syncopal VT in group 1 (14 of 129 VTs, vs 40 of 86 in group 2, p less than 0.001). Non-syncopal VT could reliably and safely be terminated by pacing in 61%, irrespective of the clinical arrhythmia. Pacing-induced acceleration of VT occurred in 6% (single extrastimuli) to 36% (over-drive pacing) (mean 26%) of attempts. Subsequent DC shock was required in half of these cases. Immediate collapse after induction of VT was not related to the presence of heart disease, but was related to a combination of VT cycle length (shorter than 260 ms) and left ventricular ejection fraction (less than 40%). Antiarrhythmic drugs reduced the need for DC shock.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Can potentially significant polymorphic ventricular arrhythmias initiated by programmed stimulation be distinguished from those that are nonspecific?

Polymorphic ventricular arrhythmias (PVAs) initiated by programmed electrical stimulation may be a nonspecific response or evidence of ventricular electrical instability. To determine if PVAs initiated in patients with spontaneous sustained ventricular tachycardia or fibrillation differ from those which are clearly a nonspecific response in structurally normal hearts, the initiation, characteristics, and relationship to ventricular repolarization of PVAs greater than five beats in duration were evaluated in 32 patients without structural heart disease and in 36 patients with spontaneous sustained ventricular arrhythmias more than 9 days after myocardial infarction. Patients received one to four extrastimuli during sinus rhythm and right ventricular pacing. In a comparison with patients who completed the same steps (defined by the basic drive cycle length and number of extrastimuli) in the stimulation protocol, there was no difference in the cumulative risk of initiation of a PVA between the patients with and those without heart disease at any step. This risk was 51% vs 38% for patients who received two or fewer extrastimuli at four basic cycle lengths (p = NS). PVAs were initiated by the same mean number of extrastimuli (2.3 +/- 0.5 vs 2.6 +/- 0.9 p NS) with the same degree of prematurity in both groups. Forty-four percent of the PVAs in the myocardial infarction group had a cycle length greater than 250 msec or a coupling interval of the first tachycardia beat to its initiating stimulus greater than 320 msec as opposed to only one (6%) in the group without heart disease (p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Effects of early reperfusion in acute myocardial infarction on arrhythmias induced by programmed stimulation: a prospective, randomized study.

This study compares inducibility of ventricular tachyarrhythmias by programmed electrical stimulation of the heart in patients with myocardial infarction with and without reperfusion after streptokinase therapy. Sixty-two consecutive patients admitted with an acute myocardial infarction were randomized to either combined intravenous and intracoronary streptokinase (streptokinase group) or to standard coronary care unit treatment (control group). Thirty-six of the 62 patients (21 patients from the streptokinase and 15 from the control group) with a first myocardial infarction were studied by programmed ventricular stimulation after a mean of 26 +/- 14 days. No patient had a history of antiarrhythmic drug use or documentation of a ventricular arrhythmia before the initial admission. A sustained ventricular arrhythmia was induced in 10 (48%) of the 21 patients randomized to streptokinase therapy and in all 15 (100%) control patients (p less than 0.001). Sustained monomorphic ventricular tachycardia was induced in 6 (29%) and 10 (67%) patients, respectively (p less than 0.05). To terminate an induced arrhythmia, direct current countershock was required in 33% of patients in the streptokinase group and 73% of patients in the control group (p less than 0.02). Seventeen of the 21 patients treated with streptokinase and no control patient had evidence of early reperfusion 200 +/- 70 minutes after the onset of pain. In comparison with patients without early reperfusion, patients in the reperfused group had a lower maximal serum creatine kinase value (p less than 0.01), a shorter time to peak creatine kinase value (p less than 0.001) and a higher angiographic left ventricular ejection fraction (62 versus 45%, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

Ventricular arrhythmias initiated by programmed stimulation in four groups of patients with healed myocardial infarction.

Programmed electrical stimulation of the heart was prospectively used in 160 patients with healed myocardial infarction to study the incidence and characteristics of ventricular arrhythmias induced. Thirty-five patients had neither documented nor suspected ventricular arrhythmias (Group A); 37 patients had documented nonsustained ventricular tachycardia (Group B); 31 patients had been resuscitated from ventricular fibrillation (Group C); and 57 patients had documented sustained monomorphic ventricular tachycardia (Group D). No electrophysiologic differences were found between patients in Group A and Group B, but patients in both groups differed significantly from patients in Group C and Group D. In the last two groups, sustained monomorphic ventricular tachycardia was more frequently induced, the cycle length of the induced ventricular tachycardia was slower and a lesser number of premature stimuli was required for induction. No differences were found in the incidence, rate or mode of induction of nonsustained monomorphic ventricular tachycardia, but nonsustained polymorphic ventricular tachycardia and ventricular fibrillation were more frequently induced in Groups A and B. It is concluded that the substrate for sustained ventricular arrhythmia is present in at least 42% of patients after myocardial infarction. The electrophysiologic characteristics of the substrate for ventricular tachycardia seem to be the major determinant of the clinical occurrence of sustained ventricular arrhythmia. Changes in the electrophysiologic properties of the substrate of ventricular tachycardia, either spontaneously with time or induced by ischemia or antiarrhythmic drugs, can contribute to the clinical occurrence of sustained ventricular arrhythmias in patients with an old myocardial infarction.

Anti-Arrhythmia Agents↗
PubMed1986

[Initial experiences with nuclear spin tomography of bone diseases].

The results of MRT in 41 patients with bone diseases are reported. MRT proved to be a sensitive method in evaluating localised bone lesions. MR provided definite advantages in comparison with computed tomography and plain films in the determination of the intramedullary and extraosseous extent of circumscribed bone lesions. A better characterisation of the nature and histology of bone changes was not possible with MRT. Diffuse bone marrow disease are well demonstrable via MRT.

Adult↗
PubMed1986

Role of programmed electrical stimulation of the heart in the selection and design of implantable units for the treatment of recurrent tachycardia.

The introduction of programmed electrical stimulation of the heart opened up new ways for the diagnosis and treatment of recurrent tachycardias. Programmed stimulation not only allows study of the site of origin and mechanisms of arrhythmias, but also the evaluation of the modes of reproducible initiation and termination of tachycardia and the study of effects of drugs on the tachycardia mechanisms. By analyzing results of invasive and non-invasive programmed stimulation, the most successful pacing modality to reproducibly terminate tachycardia can be identified, but complications of pacing can also be recognized (such as the initiation of other arrhythmias). Careful consideration of the results of programmed electrical stimulation is necessary to select the best implantable unit for a particular patient, and to design or redesign new or already implanted antitachycardia units.

Arrhythmias, Cardiac↗
PubMed1985

Arrhythmias induced during termination of supraventricular tachycardia.

Pacing is being used frequently for the treatment of drug-resistant, paroxysmal supraventricular tachycardias (SVT). SVT can usually be terminated by pacing, but arrhythmias may be induced which interfere with the safety of antitachycardia pacing. To quantify these pacing-induced arrhythmias, 453 attempts to terminate SVT in 111 patients were analyzed. The patients were 6 to 73 years old (mean 41); 62 were male. Seventy-six patients had SVT using an accessory atrioventricular bypass, and 35 patients had intranodal SVT. Single and then, if required, multiple ventricular and atrial premature beats and overdrive pacing were delivered from the atrium and ventricle. A pacing-induced arrhythmia occurred in 9% of all attempts (34% of patients). Atrial flutter or fibrillation (AF) was the most frequent arrhythmia (in 8% of all attempts and sustained in 75%). Atrial vs ventricular pacing resulted in a 12% vs 2% incidence of AF. AF was unrelated to age, sex, atrial size and SVT type, and was predominantly induced by multiple premature beats. In 6 patients a different SVT and in 2 patients a nonsustained ventricular tachycardia was induced. In 6 patients SVT could only be terminated by initiating another arrhythmia. Thus, AF is frequently induced during attempted pacing termination of SVT. To limit the risk of AF, a single premature beat should preferentially be used to terminate SVT. In 6% of patients, SVT can only be terminated by inducing another arrhythmia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Automatic pacemaker termination of two different types of supraventricular tachycardia.

A new antitachycardia pacemaker system was used in a 58 year old woman to terminate two different types of supraventricular tachycardia by a single automatic pacing mode. During the invasive electrophysiologic study before pacemaker implantation (in the absence of medication), sustained episodes of atrioventricular (AV) nodal reentrant tachycardia and two short-lasting episodes of nonsustained atrial tachycardia were induced. After implantation, sustained episodes of both AV nodal tachycardia and atrial tachycardia were initiated. Both arrhythmias could be terminated reproducibly by a single pacing mode.

Automation↗
PubMed1985

Clinical, angiographic, and electrophysiologic findings in patients with aborted sudden death as compared with patients with sustained ventricular tachycardia after myocardial infarction.

After the acute phase of myocardial infarction, patients who develop sustained ventricular arrhythmias present with either sudden death or ventricular tachycardia (VT). Although current evidence suggests that VT frequently precedes ventricular fibrillation (VF) in patients presenting with sudden death, the factors resulting in rapid deterioration of VT to VF have not been delineated in humans. To determine whether left ventricular function, coronary anatomy, or electrophysiologic characteristics could differentiate patients with sudden death from those with VT without sudden death, we compared results of cardiac angiography and programmed electrical stimulation in 42 patients referred for evaluation of sustained VT or surviving "aborted" sudden death for more than 9 days after myocardial infarction. By univariate analysis there were no differences between patients with sudden death and those with VT in age, time from myocardial infarction to VT or sudden death, ejection fraction (0.31 +/- 0.12 vs 0.29 +/- 0.09), or the number of patients with a major area of contracting myocardium supplied by an artery with a 50% or greater or a 70% or greater stenosis (84% vs 64% and 68% vs 41%). Thirty-six percent of patients with sudden death but no patient with VT had two separate areas of infarction. During programmed electrical stimulation, a sustained ventricular arrhythmia was initiated in 100% of patients with VT and 73% of patients with sudden death and rapidly produced syncope in 67% of patients with sudden death but in only 5% of those with VT. This difference was due to the more frequent initiation of rapid polymorphic VT or VF (27% of patients) and to the shorter VT cycle length (242 +/- 31 vs 319 +/- 69 msec) when monomorphic VT was induced in the group with sudden death. No difference was found in the number of extrastimuli required for initiation of a sustained ventricular arrhythmia.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1983

[Prolapse of the lumbar vertebral disk--correlation of CT and myelographic findings with surgical findings].

Side by side with myelography, computed tomography is growing in importance as far as the diagnosis of the lumbar compression syndrome is concerned. From May 1980 to the end of April 1982, the authors employed at the Cologne University Clinic of Orthopaedics in 176 patients operated either for the first time or several times, myelography alone in 54 cases, and myelography combined with computed tomography in 98 cases, whereas computed tomography alone was used 24 times, in each case for the purpose of preoperative diagnosis. An epicritical analysis of the two last-named groups of examinations, basing on the findings made as a result of the operation, showed that computed tomography was superior in respect of the accuracy in determining the level and affected side of the compression. Two CT examinations only could not be utilised for technical reasons. Nine false-positive or false-negative cases (plus two examinations which were useless for technical reasons) were seen among the 98 myelographies of the patient group in question. Besides the equivalent information given by computed tomography in respect of the level and side of the compression, CT supplies additional information regarding constriction of the vertebral canal, defined osseous stenoses, preference for a particular side and site of prolapsed disk tissue, and on the cause of the compression in case there is a considerable stoppage of contrast medium. Computed tomography is better suited than myelography in the immediate postoperative phase for follow-up examinations which are aimed at differentiating renewed prolapses, haemorrhages, or cicatrised changes. Provided there is enough capacity for examination, it seems possible that the noninvasive computed tomography will eventually replace invasive myelography as a routine examination method in case of relevant indications.

Diagnostic Errors↗
PubMed1983

[Surgically verified CT findings after previous lumbar discotomy].

Our experience has shown that computed tomography is superior to myelography as a diagnostic tool after lumbar discotomy. Provided the examination is carried out correctly, CT has always supplied a precise anatomic diagnosis in cases where the myelogram was ambiguous. In particular, it was possible to differentiate between discogenic, cicatrized, haematoma-conditioned and osseous compression. However, two facts have to be reiterated: 1. The reference method in the cases under report was exclusively the surgical finding, representing a relatively clearly defined part of the patient material. 2. It goes without saying that the indication for a repeat operation must be based on the clinical findings as well.

Adult↗