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Biomedical subjects

Christof Kolb

Publications and source records attributed to Christof Kolb.

17 recordsLinked to original sources
PubMed2006

Near-fatal incident on routine induction of ventricular fibrillation at the replacement of an implantable cardioverter defibrillator.

The case of a 54-year-old patient with severe coronary artery disease and storms of ventricular tachyarrhythmias is presented. On the replacement of an implantable cardioverter defibrillator due to battery depletion, he suffered life-threatening complications associated with arrhythmia induction. Performing a routine induction of ventricular arrhythmias on the occasion of pulse generator replacement may be reconsidered in selected patients.

Defibrillators, Implantable↗
PubMed2006

Implantable cardioverter defibrillator (ICD) in children.

BACKGROUND: Implantable cardioverter defibrillators (ICD) proved to be effective in the prevention of sudden cardiac death in adults. In children, the experience of ICD therapy is limited. This retrospective study was undertaken to review our experience with ICD implantation in children with special consideration of psychosocial impact of this therapy. METHODS AND RESULTS: Sixteen children (f:5, m:11, median age 12.2 years, range 4-15.9 years) received an ICD. Eleven patients had survived sudden cardiac death with documented ventricular fibrillation (VF) and five patients had sustained ventricular tachycardia (VT) with hemodynamic significance. The underlying heart disease was congenital in 5, hypertrophic cardiomyopathy in 2, myocarditis in 2 and primary electrical in 7 patients. All leads were implanted transvenously. Mean follow up was 43.1 months (range 1-105 months). All patients are alive. In 7 patients, a total of 387 sustained VT episodes were detected by the ICD. At follow-up, 10 inappropriate shocks were delivered in four patients. One early and six late lead revisions were done in seven patients. 12/16 (75%) patients had concomitant antiarrhythmic drug therapy. About half of the adolescents showed signs of depression and/or anxiety. CONCLUSION: ICD therapy via transvenous access for prevention of sudden cardiac death is feasible and effective even in small children. However, the occurrence of lead complications is significant. Since about half of the adolescents showed signs of depression and/or anxiety, professional psychological surveillance should be considered in these patients.

Adolescent↗
PubMed2006

Long-term follow-up of patients supplied with single-chamber or dual-chamber cardioverter defibrillators.

INTRODUCTION: In patients who have an indication for an implantable cardioverter defibrillator (ICD) a dual-chamber device is indicated in the case of concomitant significant sinus node disease or atrioventricular block. It is a matter of debate whether dual-chamber ICD may be beneficial for patients with preserved sinus and atrioventricular nodal function as data from prospective randomized trials are limited. Mid- or long-term follow-up data are unavailable. METHODS AND RESULTS: One hundred patients (age 60+/-12 years, 11 women) with the indication for the implantation of an ICD and without antibradycardia pacing indication were randomly assigned to either receive a dual-chamber ICD (n=52) or a single-chamber ICD (n=48). Patients were followed-up for a mean of 52+/-14 months. Mortality and arrhythmogenic morbidity were assessed. All-cause mortality was 21% for single-chamber and 31% for dual-chamber ICD recipients, respectively (P=0.26). Cardiovascular mortality was 13% for single-chamber ICD recipients versus 21% in the dual-chamber group (P=0.25). Subgroup analysis using 35% of ventricular paced beats as cutoff value in the dual-chamber ICD group revealed a 42% mortality rate for the patients with frequent ventricular pacing compared to 10% of patients with a low rate of ventricular pacing (P=0.05, relative risk 4.21, 95% confidence interval: 0.9-19.8). As for arrhythmogenic morbidity, the difference in the ventricular tachyarrhythmia load was not different in both groups (single chamber: 23+/-74 VT episodes, dual chamber: 54+/-134 VT episodes, P=0.17). CONCLUSION: In ICD recipients without conventional indication for dual-chamber pacing, dual chamber compared to single-chamber ICD has no advantage concerning mortality and arrhythmogenic morbidity in a long-term follow-up. In these patients the implantation of a single-chamber device is sufficient.

Arrhythmias, Cardiac↗
PubMed2006

Cardiac pacing in a patient with diaphragm pacing for congenital central hypoventilation syndrome (Ondine's curse).

Mechanical ventilation support and diaphragm pacing has improved the prognosis of patients with idiopathic congenital central hypoventilation syndrome (CCHS; Ondine's curse). However, severe bradyarrhythmias may occur. This report is about a patient who was supplied with a bilateral diaphragm pacing system at early childhood. At the age of 17 years, he experienced multiple syncopes due to sinus nodal arrest, which was successfully treated by the implantation of a dual chamber pacemaker.

Adolescent↗
PubMed2006

Management of far-field R wave sensing for the avoidance of inappropriate mode switch in dual chamber pacemakers: results of the FFS-test study.

BACKGROUND AND OBJECTIVE: Far-field R wave sensing (FFS) in the atrial channel of dual chamber pacemakers is a relevant source for inappropriate mode switch from the DDD mode to the DDI or VDI mode. Inappropriate loss of atrioventricular synchrony due to false positive mode switch is hemodynamically disadvantageous, may induce atrial tachyarrhythmias, can lead to pacemaker syndrome, and impairs the reliability of pacemaker Holter data. The aim of the study was to determine whether individual adjustment of the postventricular atrial blanking period (PVAB) based on an additional test is effective in avoiding inappropriate mode switch due to FFS when compared with standard programming of the PVAB. METHODS: A total of 207 patients were supplied with a St. Jude Medical Identity DR or Identity ADx DR dual chamber pacemaker for sinus nodal disease (n = 84), atrioventricular block (n = 79), binodal disease (n = 35), or other indications (n = 9). At hospital discharge, they were randomized to an individually optimized PVAB (n = 100) or to a control group with the PVAB left at the nominal of 100 msec (n = 107). Primary endpoint was the occurrence of inappropriate mode switch due to FFS within 3 months after pacemaker implantation assessed by stored electrograms of the pacemaker. RESULTS: At the 3-month follow-up, 28/107 (26%) patients with the standard programming of the PVAB showed at least one episode of inappropriate mode switch due to FFS versus 10/100 (10%) patients with optimized PVAB (P < 0.01). The optimized PVAB was shorter than the nominal PVAB in about one-third of patients and longer in about two-third of patients. Different atrial lead localizations were not associated with the occurrence of inappropriate mode switch. CONCLUSIONS: Individual adjustment of the PVAB significantly reduces the incidence of inappropriate mode switch due to FFS.

Aged↗
PubMed2005

Vanguard--a European robotic astrobiology-focussed Mars sub-surface mission proposal.

We present a new European Mars mission proposal to build on the UK-led Beagle2 Mars mission and continue its astrobiology-focussed investigation of Mars. The small surface element to be delivered to the Martian surface--Vanguard--is designed to be carried by a Mars Express-type spacecraft bus to Mars and adopts a similar entry, descent and landing system as Beagle2. The surface element comprises a triad of robotic devices--a lander, a micro-rover of the Sojourner class for surface mobility, and three ground-penetrating moles mounted onto the rover for sub-surface penetration to 5 m depth. The major onboard instruments on the rover include a Raman spectrometer/imager, a laser plasma spectrometer, an infrared spectrometer--these laser instruments provide the basis for in situ "remote" sensing of the sub-surface Martian environment within a powerful scientific package. The moles carry the instruments' sensor head array to the sub-surface. The moles are thus required to undergo a one-way trip down the boreholes without the need for recovery of moles or samples, eliminating much of the robotic complexity invoked by such operations.

Equipment Design↗
PubMed2005

Successful pacemaker lead implantation via the subclavian vein despite of high degree stenosis of the vein.

This case reports on an 81-year-old man with implanted dual-chamber pacemaker for binodal disease who required ventricular lead revision due to loss of ventricular capture. Successful placement of a new lead via the subclavian vein despite of high degree stenosis of the medial part of the vein is described using a very thin bipolar ventricular pacing lead. Currently available pacing electrodes for this purpose are reviewed.

Aged↗
PubMed2005

Accidental transarterial implantation of dual chamber pacemaker leads in the left ventricle and the right coronary artery.

Implantation of permanent pacemaker systems is associated with a low rate of complications. The case of a 72-year-old woman is described who suffered from a cluster of complications related to permanent pacemaker implantation. Besides major bleeding, requiring transfusion and pneumothorax, malposition of both pacemaker leads in the arterial system occurred, with the atrial lead screwed into the right coronary artery, with subsequent occlusion of the vessel and the ventricle lead placed in the left ventricle.

Aged↗
PubMed2005

Paradoxical atrial undersensing due to inappropriate atrial noise reversion of atrial fibrillation in dual-chamber pacemakers.

UNLABELLED: Paradoxical atrial undersensing. BACKGROUND: Paradoxical atrial undersensing at high atrial sensing levels was described as false atrial noise reversion of dual-chamber pacemakers during atrial fibrillation in a sheep model. It is unknown whether this phenomenon occurs in humans. METHODS: In total, 71 patients with implanted dual-chamber pacemakers and atrial fibrillation were tested for the occurrence of paradoxical atrial undersensing. After determination of the sensing threshold of atrial fibrillation (30 seconds of continuous mode switch), the atrial sensing level was stepwise increased. If, after correct mode switch behavior at insensitive levels, loss of mode switch occurred at higher sensing levels and if the pacing mode was consistent with atrial noise reversion, paradoxical atrial undersensing was assumed. RESULTS: Paradoxical atrial undersensing could be provoked in 9 of 71 (13%) patients at a median sensing level of 0.4 (range 0.15-2.0) mV. Six different pacemaker models of five different manufacturers were affected. The occurrence of paradoxical atrial undersensing was significantly associated with the sensing threshold of atrial fibrillation (2.7+/-1.5 mV for patients with paradoxical undersensing compared to 1.6+/-1.3 mV for those without, P=0.02). Decreasing the atrial sensing level avoided paradoxical undersensing in 8 of 9 patients while maintaining an adequate safety margin for the detection of atrial fibrillation. CONCLUSION: Paradoxical atrial undersensing is inherent to all current dual-chamber pacemakers. The incidence is about 13% when using very high atrial sensing levels. Inappropriate atrial noise reversion can be resolved in most of the cases by decreasing atrial sensing levels and knowledge of this phenomenon is important to avoid unwarranted atrial lead revisions.

Aged↗
PubMed2004

Questionable dysfunction of a dual-Chamber pacemaker in a 17-year-old female: differential diagnoses of missing ventricular beats.

The case of a 17-year-old female who had been implanted a dual-chamber DDD pacemaker because of third-degree atrioventricular block is reported. There is a history of continued dizziness and even occasional syncopes. At heart rates of 111/min to 124/min, 24-h Holter electrocardiography revealed isolated missing ventricular beats in an otherwise continuous atrially sensed and triggered, ventricularly paced rhythm. Differential diagnoses of a putative pacemaker dysfunction are presented, comprising 2:1-block at maximum programmed heart rate, intermittent lead fracture, anti-pacemaker-mediated tachycardia algorithm, ventricular oversensing, P wave signal undersensing, and atrial oversensing.

Adolescent↗
PubMed2004

Preventricular far-field sensing in the atrial channel of dual chamber pacemakers--an occasional cause of inappropriate mode switch.

INTRODUCTION AND AIMS OF THE STUDY: Atrial oversensing may trigger false positive mode switch to an asynchronous mode in dual chamber pacemakers. While myopotential oversensing and far-field R wave sensing within the postventricular atrial refractory period are well characterized, data about oversensing (near-field P wave or far-field R wave) within the atrioventricular delay is limited. Aim of the study was to determine the incidence of preventricular oversensing in the atrial channel of current dual chamber pacemakers. METHODS: Consecutive patients with dual chamber pacemakers who were in sinus rhythm and who showed no myopotential oversensing were included in the study. Atrial sensitivity was programmed to the maximal available value and atrioventricular delay was prolonged when necessary for intrinsic atrioventricular conduction. RESULTS: Ten out of 100 (10%) patients showed oversensing within the atrioventricular delay at highest levels of atrial sensitivity, median sensing threshold for the signals was 0.35 mV, and the median coupling interval between preventricular atrial oversensing and the ventricular sensed event was 20 ms. CONCLUSION: The incidence of inappropriate mode switch caused by atrial preventricular oversensing related to near-field P wave or far-field R wave oversensing in dual chamber pacemakers is up to 10%. Interpretation of pacemaker Holters should consider oversensing within the atrioventricular delay as a differential diagnosis to true episodes of atrial tachyarrhythmias.

Adolescent↗
PubMed2004

Incidence of antitachycardia therapy suspension due to magnet reversion in implantable cardioverter defibrillators.

Electromagnetic interference may result in transient or persistent suspension of antitachycardia therapies in ICDs. The incidence of such events has not been assessed so far. Patient charts were retrospectively analyzed for the occurrence of temporary suspension of antitachycardia therapies as it is stored in the Holter of St. Jude Medical or Ventritex ICDs. Follow-up data of 46 patients and 83.7-patient years were analyzed. Overall, 43 episodes of transient ICD inactivation occurred. Twenty-two of these episodes were related to intentional ICD inactivation in the emergency room or during surgery and 12 episodes were related to ICD follow-up. In nine episodes an environmental source of electromagnetic interference is presumed. None of the interactions resulted in persistent ICD inactivation or reprogramming of the devices. The risk for temporary suspension of ICD therapies unrelated to surgery, intentional magnet application in the emergency room, or routine follow-up is 11% per patient and year. Evaluation of its potential sources and the prevalence of ICD inhibition is warranted.

Adolescent↗
PubMed2003

Do airport metal detectors interfere with implantable pacemakers or cardioverter-defibrillators?

OBJECTIVES: The aim of this study was to determine whether airport metal detector gates (AMDGs) interfere with pacemakers (PMs) or implantable cardioverter-defibrillators (ICDs). BACKGROUND: It is currently unknown whether AMDGs interfere with implanted PMs or ICDs. METHODS: A total of 348 consecutive patients (200 PM and 148 ICD recipients) have been tested for the occurrence of electromagnetic interference (EMI) within the electromagnetic field of a worldwide-used airport metal detector. RESULTS: No interference, such as pacing or sensing abnormalities, was observed in any of the 200 PM and 148 ICD patients; also no reprogramming occurred. CONCLUSIONS: In vivo testing of PM and ICD systems showed no EMI with a standard AMDG. Clinically relevant interactions with implanted PMs or ICDs seem unlikely.

Adolescent↗
PubMed2003

Strategies to avoid inappropriate therapies due to ventricular double detection in biventricular pacing implantable cardioverter/defibrillators.

Implantation of biventricular pacing implantable cardioverter/defibrillators (ICD) is a new therapeutic approach for the treatment of chronic heart failure and the prevention of sudden cardiac death. Due to a common left and right ventricular sensing channel in first generation biventricular pacing ICD, ventricular double sensing and subsequent delivery of inappropriate therapies occurs in some patients. A case of inappropriate anti-tachycardia pacing due to ventricular double detection is described. After programming short postventricular atrial refractory period, abandoning postventricular atrial refractory period extension in case of ventricular premature beats, increased upper rate limits and after careful selection of tachycardia detection criteria and anti-tachycardia programming no further inappropriate therapy occurred.

Aged↗
PubMed2002

Inappropriate shock delivery due to interference between a washing machine and an implantable cardioverter defibrillator.

Electromagnetic interference with implantable cardioverter defibrillators (ICD) can cause inappropriate delivery of therapies or temporary inhibition of ICD functions. The presented case describes electromagnetic interference between a washing machine and an ICD resulting in an inappropriate discharge of the device due to false detection of ventricular fibrillation.

Adult↗