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Biomedical subjects

S Windecker

Publications and source records attributed to S Windecker.

36 records · Page 2Linked to original sources
PubMed2001

Evolution of percutaneous transluminal coronary angioplasty in Europe from 1992-1996.

BACKGROUND: The working group Coronary Circulation of the European Society of Cardiology has been conducting a yearly survey on coronary interventions in Europe. The purpose of this study is to present the evolution of percutaneous transluminal coronary angioplasty (PTCA) with epidemiological and economic implications. METHODS: Coronary interventions were polled by questionnaires distributed to all institutions performing cardiac catheterization. Aggregated country data of the years 1992-1996 on indication, type of procedure, technique, and outcome of coronary interventions were analysed. RESULTS: Population-adjusted coronary angiographies and PTCA procedures increased by 76% and by 105%, respectively. The Percentage of coronary stenting increased from zero to almost half of all procedures. Analysis per country groups reveals considerable variation, ranging, e.g. for PTCA in 1996 from 157 procedures per million population in a group of eastern countries to 1138 in a central European group. Relating total revascularization (R) to standardized death rate for ischaemic heart disease (SDR) and to gross domestic product (GDP), there was an increase from 1.0 to 1.8 R/SDR and 40 to 61 R/GDP in the central European group compared with an increase from 0.06 to 0.18 R/SDR and 43 to 85 R/GDP in the eastern group. CONCLUSIONS: An overall increase in PTCAs at an annual rate between 15 and 25% was observed. The wide variation in the use of PTCA in Europe appears to be dependent mostly on economic factors and national health care policies.

Angioplasty, Balloon, Coronary↗
PubMed2001

Percutaneous closure of patent foramen ovale in symptomatic patients.

BACKGROUND: Patent foramen ovale (PFO) and atrial septal aneurysm (ASA) have been associated with stroke in young adults. Patients with PFO suffering from paradoxical embolism are at increased risk for recurrent events. Percutaneous PFO closure is a new treatment modality aimed at secondary prevention. METHODS AND RESULTS: Since April 1994, 132 consecutive patients, aged 51 +/- 12 years with PFO and with at least one paradoxical embolic event, underwent percutaneous PFO closure using six different device types. The embolic index event was an ischemic stroke in 62% of patients, a transient ischemic attack (TIA) in 33% of patients, and a peripheral embolism in 5% of patients. Thirty-six (27%) patients had PFO associated with ASA, whereas 96 (73%) patients had PFO only. The implantation procedure was successful in 130 (98%) patients. During and up to 6 years of follow-up (mean 1.8 +/- 1.6 years, 231 patient years), a total of eight recurrent embolic events were observed, with six TIAs, two peripheral emboli, and no ischemic stroke. The actuarial freedom from recurrence of the combined end point of TIA, ischemic stroke, and peripheral embolism was 95.3% (95% confidence interval [CI], 91.0%-96.4%) at 1 year and 90.5% (95% CI, 83.6%-97.2%) at 6 years. CONCLUSIONS: Percutaneous PFO closure can be performed with a high success rate. The procedure appears a promising therapeutic modality for secondary prevention of recurrent embolism in patients with PFO. Randomized trials must define its therapeutic value.

Adult↗
PubMed2001

Patent foramen ovale: pathophysiology and therapeutic options in symptomatic patients.

The foramen ovale, a remnant from the fetal circulation, remains patent through adulthood in approximately 1/4th of the general population, thus representing the most common persistent abnormality of fetal origin. In these individuals, the patent foramen ovale (PFO) permits interatrial right-to-left shunting during those periods of time when right atrial exceeds left atrial pressure. Recently, the pathophysiological aspects of the PFO have been increasingly appreciated, giving rise to disease manifestations such as paradoxical embolism, refractory hypoxemia in patients with right ventricular infarction or severe pulmonary disease, orthostatic desaturation in the setting of the rare platypnea-orthodeoxia syndrome, neurological decompression illness in divers, and migraine headache with aura. Despite the growing recognition of the PFO, particularly when associated with an atrial septal aneurysm, as risk factor for paradoxical embolism, the optimal treatment strategy for symptomatic patients remains undefined. Most patients with presumed paradoxical embolism are currently treated medically with antithrombotic medications, with a paucity of data concerning the efficacy of oral anticoagulant as opposed to antiplatelet therapy. Surgical PFO closure has proved feasible, but the procedure is associated with the well known complications of cardiac surgery, and the results have been mixed with respect to stroke prevention. The recent introduction of interatrial septal occlusion devices set the stage for a minimally invasive, percutaneous approach. The present article discusses the pathophysiology of the PFO, and the advantages and drawbacks of the different therapeutic options available for symptomatic patients.

Embolism, Paradoxical↗
PubMed2000

[Non-surgical closure of patent ductus arteriosus: acute and long-term results].

INTRODUCTION: Closure of a patent ductus arteriosus (PDA) even with small shunt volumes in asymptomatic patients is recommended because of the risk of endocarditis (1.5% per year) and the potential development of congestive heart failure or pulmonary hypertension. METHODS: 16 patients (9 adults [5 men/4 women] and 7 children [3 boys/4 girls]) underwent transcatheter closure of a PDA. The intervention was performed using the Rashkind umbrella in 12 cases, the Amplatzer duct occluder in 2 cases, a coil in 2 cases, and the Sideris self-adjusting device in one case. Echocardiographic controls were carried out one day, 6 months, 12 months and 24 months after the intervention. RESULTS: PDA closure was complete immediately following the intervention in 9 of 16 patients (56%). At follow-up (mean 19 months) complete closure was observed in 14 of 16 patients (87%). All residual shunts were trivial. The complete closure rate in adults was 100% and in children 71%. Complications such as device embolism, endarteritis and haemolysis did not occur. CONCLUSION: Non-surgical closure of a PDA is a safe and effective technique.

Adult↗
PubMed2000

Percutaneous closure of patent foramen ovale in patients with paradoxical embolism: long-term risk of recurrent thromboembolic events.

BACKGROUND: Patients with a patent foramen ovale (PFO) and paradoxical embolism are at risk for recurrent thromboembolic events. This study investigated the long-term risk of recurrent thromboembolic events in patients with PFO and paradoxical embolism after percutaneous PFO closure. METHODS AND RESULTS: Since 1994, a total of 80 patients with PFO and at least 1 paradoxical embolic event (transient ischemic attack [TIA], cerebrovascular accident [CVA], peripheral embolism) have undergone percutaneous PFO closure with 5 different devices. There were 30 women and 50 men, with a mean age of 52+/-12 years. Sixty patients had only a PFO, whereas 20 patients had both a PFO and an atrial septal aneurysm. The implantation procedure was successful in 78 patients (98%). During 5 years of follow-up (mean, 1.6+/-1.4 years; range, 0.1 to 5.0 years), the actuarial annual risk to suffer a recurrent thromboembolic event was 2.5% for TIA, 0% for CVA, 0.9% for peripheral emboli, and 3.4% for the combined end point of TIA, CVA, or peripheral embolism. A postprocedural shunt was a predictor of recurrent paradoxical embolism (RR, 4.2; 95% CI, 1.1 to 17.8; P=0.03). The risk for recurrent thromboembolic events in patients with both atrial septal aneurysm and PFO was not significantly increased compared with patients with only PFO (RR, 1.0; 95% CI, 0.2 to 4.7; P=0.95). CONCLUSIONS: Percutaneous PFO closure appears to be a promising technique in the prevention of recurrent systemic thromboembolism in patients with a PFO after a first event. Prospective studies comparing percutaneous PFO closure with antithrombotic medications or surgery must define its therapeutic value.

Actuarial Analysis↗
PubMed2000

Mechanical compression of coronary artery stents: potential hazard for patients undergoing cardiopulmonary resuscitation.

Mechanical compression of coronary artery stents may be associated with a fatal outcome as the result of refractory myocardial ischemia. We present the history of an 83-yr-old patient, who died owing to hemorrhagic shock 3 days after stent implantation, despite immediate cardiopulmonary resuscitation (CPR). Postmortem examination showed stent compression, probably due to mechanical deformation during CPR. This complication has been reported in two other cases in the literature, suggesting that CPR may be hazardous to patients with coronary artery stents.

Aged↗
PubMed2000

Surgical management of complications after transcatheter closure of an atrial septal defect or patent foramen ovale.

OBJECTIVE: During recent years, transcatheter closure has become an alternative to operations for the treatment of atrial septal defects and patent foramen ovale. However, this procedure may be unsuccessful or complicated and requires surgical treatment. METHODS: We retrospectively analyzed the outcomes of patients who needed surgical treatment after failed or complicated transcatheter closure of an atrial septal defect or a patent foramen ovale. RESULTS: Between April 1994 and March 1999, 124 patients were treated with transcatheter closure of an atrial septal defect or a patent foramen ovale at our institution. We report the results of 10 (8%) patients of this series who required operations after transcatheter closure attempts. In 8 of these 10 patients a significant shunt caused by malposition or dislocation of the device persisted, leading to surgical closure of the defect. In 2 patients injury of the femoral artery at the puncture site required surgical repair. In one patient the device had to be removed surgically from the iliac vein after retraction. One patient died of left ventricular perforation after dislocation of the device and several surgical attempts to close the left ventricular rupture. All other patients recovered well. CONCLUSION: An operation was required after transcatheter closure of an atrial septal defect or a patent foramen ovale in 8% of patients. After device complications, the atrial septal defect and the patent foramen ovale can still successfully be closed surgically with good results and low morbidity. However, serious complications like cardiac perforation may have a fatal outcome. Residual shunt, dislocation, or vascular complications are the most frequent problems that require surgical interventions.

Adolescent↗
PubMed1999

The influence of ventricular fibrillation duration on defibrillation efficacy using biphasic waveforms in humans.

OBJECTIVES: The purpose of this study was to prospectively investigate the influence of ventricular fibrillation (VF) durations of 5, 10 and 20 s on the defibrillation threshold (DFT) during implantable cardioverter-defibrillator (ICD) implantation. BACKGROUND: Although the DFT using monophasic waveforms has been shown to increase with VF duration in humans, the effect of VF duration on defibrillation efficacy using biphasic waveforms in humans is not known. METHODS: Thirty patients undergoing primary ICD implantation or pulse generator replacement were randomly assigned to have the DFT determined using biphasic shocks at two durations of VF each (5 and 10 s, 10 and 20 s or 5 and 20 s). RESULTS: There was no statistically significant difference in the mean DFT comparing VF durations of 5 s (9.5+/-6.0 J) and 10 s (10.8+/-7.0 J) (p=0.4). The mean DFT significantly increased from 10.9+/-6.1 J at 10 s of VF to 12.6+/-5.6 J (p=0.03) at 20 s of VF, and from 7.0+/-3.5 J at 5 s of VF to 10.5+/-6.3 J (p=0.04) at 20 s of VF. An increase in the DFT was observed in 14 patients as VF duration increased. There were no clinical characteristics that differentiated patients with and without an increase in the DFT. CONCLUSIONS: Defibrillation efficacy decreases with increasing VF duration using biphasic waveforms in humans. Ventricular fibrillation durations greater than 10 s may negatively affect the effectiveness of ICD therapy.

Aged↗
PubMed1999

Influence of left ventricular relaxation on the pressure half time of aortic regurgitation.

BACKGROUND: The severity of aortic regurgitation can be estimated using pressure half time (PHT) of the aortic regurgitation flow velocity, but the correlation between regurgitant fraction and PHT is weak. AIM: To test the hypothesis that the association between PHT and regurgitant fraction is substantially influenced by left ventricular relaxation. METHODS: In 63 patients with aortic regurgitation, subdivided into a group without (n = 22) and a group with (n = 41) left ventricular hypertrophy, regurgitant fraction was calculated using the difference between right and left ventricular cardiac outputs. Left ventricular relaxation was assessed using the early to late diastolic Doppler tissue velocity ratio of the mitral annulus (E/ADTI), the E/A ratio of mitral inflow (E/AM), and the E deceleration time (E-DT). Left ventricular hypertrophy was assessed using the M mode derived left ventricular mass index. RESULTS: The overall correlation between regurgitant fraction and PHT was weak (r = 0.36, p < 0.005). In patients without left ventricular hypertrophy, there was a significant correlation between regurgitant fraction and PHT (r = 0.62, p < 0.005), but not in patients with left ventricular hypertrophy. In patients with a left ventricular relaxation abnormality (defined as E/ADTI< 1, E/AM< age corrected lower limit, E-DT >/= 220 ms), no associations between regurgitant fraction and PHT were found, whereas in patients without left ventricular relaxation abnormalities, the regurgitant fraction to PHT relations were significant (normal E/AM: r = 0.57, p = 0.02; E-DT< 220 ms: r = 0.50, p < 0.001; E/ADTI < 1: r = 0.57, p = 0.02). CONCLUSIONS: Only normal left ventricular relaxation allows a significant decay of PHT with increasing aortic regurgitation severity. In abnormal relaxation, which is usually present in left ventricular hypertrophy, wide variation in prolonged backward left ventricular filling may cause dissociation between the regurgitant fraction and PHT. Thus the PHT method should only be used in the absence of left ventricular relaxation abnormalities.

Adult↗
PubMed1998

Interventional cardiology in Europe 1994. Working Group Coronary Circulation of the European Society of Cardiology.

The working group Coronary Circulation of the European Society of Cardiology conducts an annual survey of cardiac interventions in Europe with the support of the national societies of cardiology. A detailed questionnaire about cardiac interventions performed during 1994 was mailed to all members of the European Society of Cardiology. Incomplete or absent data from eight national members precluded their inclusion in the final analysis. Thus, this report summarizes the cardiac interventions performed during 1994 in 29 of 37 members of the European Society of Cardiology, representing a total population of approximately 490 million inhabitants. CORONARY ANGIOGRAPHY: A total of 922,687 coronary angiograms were reported during 1994, representing an increase of 22% compared with 1993 and of 35% compared with 1992. The mean incidence of coronary angiograms was 1881/10(6) inhabitants, ranging from 4417/10(6) inhabitants in Germany to 35/10(6) inhabitants in Romania, Germany, France, Great Britain, and Italy with 50% of the European population performed 73% of all cardiac interventions. CORONARY ANGIOPLASTY: During 1994, a total of 224,722 coronary angioplasty (PTCA) procedures were reported in Europe, an increase of 22% compared with 1993 and of 52% compared with 1992. Adjusted per capita, the mean incidence of coronary angioplasty was 458/10(6) inhabitants, ranging from 1091/10(6) inhabitants in Germany to 6/10(6) inhabitants in Romania. On average, the ratio PTCA per coronary angiogram was 0.24, ranging from 0.37 in the Netherlands to 0.06 in Cyprus. Ad hoc PTCA accounted for 22% of all PTCA cases. The majority (81%) of PTCAs were restricted to a single vessel. Major complications were reported in 2% of patients undergoing PTCA, including death (0.3%), myocardial infarction (1.0%) and need for emergency coronary artery bypass grafting (0.7%). CORONARY STENTING: Coronary stents were utilized in 21,599 coronary interventions during 1994, an increase of 235% compared with 1993 and thus representing the fastest growth in interventional cardiology. The number of European countries employing stents during coronary angioplasty grew from 14 during 1993 to 24 during 1994. Elective use (38%) became the most frequent indication for coronary stenting during 1994, replacing bail-out stenting as the primary indication during 1993. OTHER NEW DEVICES: Other new interventional therapeutic devices were employed in 8827 cases. Only the Rotablator was used more frequently during 1994 as compared with 1993. All other new therapeutic devices showed a decline. Coronary ultrasound was utilized in 3032 interventions and coronary angioscopy in 304 cases during 1994. NON-CORONARY INTERVENTIONS: Valvuloplasty remained the most frequent non-coronary intervention in Europe during 1994 with a total of 2622 mitral. 609 pulmonary and 506 aortic valvuloplasties. CATHETERIZATION FACILITIES: The number of facilities per 10(6) inhabitants performing invasive cardiac procedures in Europe during 1994 ranged from 7.7 in Iceland to 0.2 in Romania (European mean 2.9). The number of trained operators per 10(6) inhabitants ranged from 24 in Germany to 0.4 in Romania (European mean 10). During 1994, a mean of 701 coronary angiograms and 170 PTCAs were performed per catheterization facility in Europe (range: 1052 coronary angiograms and 293 PTCAs per facility in Norway to 218 coronary angiograms and 37 PTCAs per facility in Romania). CONCLUSIONS: The number of both coronary angiograms and coronary angioplasties continues to grow at an annual rate of approximately 20% in Europe. There is a wide range in the amount of revascularization procedures performed between western and eastern European countries. However, countries with the lowest numbers of coronary angiograms and coronary angioplasties, e.g. Romania, also show the fastest annual growth. About one quarter of all patients undergoing coronary angiography are subsequently revascularized by coronary angioplasty. (ABSTRACT TRUN

Angioplasty, Balloon, Coronary↗
PubMed1998

Two-year experience with rate-modulated pacing controlled by mixed venous oxygen saturation.

Mixed venous oxy-hemoglobin saturation (MVO2) is a physiological variable with several features that might be desirable as a control parameter for rate adaptive pacing. Despite these desirable characteristics, the long-term reliability of the MVO2 sensor in vivo is uncertain. We, therefore, designed a study to prospectively evaluate the long-term performance of a permanently implanted MVO2 saturation sensor in patients requiring VVIR pacing. Under an FDA approved feasibility study, eight patients were implanted with a VVIR pulse generator and a right ventricular pacing lead incorporating an MVO2 sensor. In order to accurately assess long-term stability of the sensor, patients underwent submaximal treadmill exercise using the Chronotropic Assessment Exercise Protocol (CAEP) at 2 weeks, 6 weeks, and 3, 6, 9, 12, 18, and 24 months following pacemaker implantation. Paired maximal exercise testing using the CAEP was also performed with the pacing system programmed to the VVI and VVIR modes in randomized sequence with measurement of expired gas exchange after 6 weeks and 12 months of follow-up. During maximal treadmill exercise the peak exercise heart rate (132 +/- 9 vs 71.5 +/- 5 beats/min, P < 0.00001) and maximal rate of oxygen consumption (1,704 +/- 633 vs 1382 +/- 407 mL/min, P = 0.01) were significantly greater in the VVIR than in the VVI pacing mode. Similarly, the duration of exercise was greater in the VVIR than the VVI pacing mode (8.9 +/- 3.6 min vs 7.6 +/- 3.7 min, P = 0.04). The resting MVO2 and the MVO2 at peak exercise were similar in the VVI and VVIR pacing modes (P = NS). However, the MVO2 at each comparable treadmill exercise stage was significantly higher in the VVIR mode than in the VVI mode (CAEP stage 1 (P = 0.005), stage 2 (P = 0.04), stage 3 (P = 0.008), and stage 4 (P = 0.04). The correlation between MVO2 and oxygen consumption (VO2) was excellent (r = -0.93). Telemetry of the reflectance of red and infrared light and MVO2 in the right ventricle during identical exercise workloads revealed no significant change over the first 12 months of follow-up (ANOVA, P = NS). The chronotropic response to exercise remained proportional to VO2 in all patients over the first 12 months of follow-up. The time course of change in MVO2 during maximal exercise was significantly faster than for VO2. At the 18- and 24-month follow-up exercise tests, a significant deterioration of the sensor signal with attenuation of chronotropic response was noted for 4 of the 8 subjects with replacement of the pacing system required in one patient because of lack of appropriate rate modulation. Rate modulated VVIR pacing controlled by right ventricular MVO2 provides a chronotropic response that is highly correlated with VO2. This parameter responds rapidly to changes in workload with kinetics that are more rapid than those of VO2. Appropriate rate modulation provides a higher MVO2 at identical workloads than does VVI pacing. Although the MVO2 sensor remains stable and accurate over the first year following implantation, significant deterioration of the signal occurs by 18-24 months in many patients.

Adult↗
PubMed1997

The effects of ventricular fibrillation duration and a preceding unsuccessful shock on the probability of defibrillation success using biphasic waveforms in pigs.

INTRODUCTION: While the defibrillation threshold has been reported to increase with ventricular fibrillation (VF) duration for monophasic waveforms, the effect of VF duration for biphasic waveforms is unknown. METHODS AND RESULTS: The ED 50 requirements (the 50% probability of defibrillation success) for an endocardial lead system, which included a subcutaneous array, were determined by logistic regression using a recursive up-down algorithm for a biphasic waveform (6/6 msec). The study was performed in two parts, each with eight pigs. In part 1, ED 50 was compared for shocks delivered after 10 seconds of VF and for shocks delivered after 20 seconds of VF following a failed first shock at 10 seconds. Energy at ED 50 decreased from 6.5 +/- 0.9 J for shocks delivered after 10 seconds of VF to 4.9 +/- 0.8 J (P < 0.01) for shocks delivered after 20 seconds. To determine if improved second shock efficacy was a result of preconditioning by the failed first shock or a function of VF duration, part 2 of the study compared defibrillation efficacy between shocks delivered after 10 seconds of VF with shocks delivered after 20 seconds of VF with and without a failed first shock at 10 seconds. Mean energy at ED 50 decreased from 10.1 +/- 2.4 J for shocks delivered after 10 seconds of VF to 7.9 +/- 2.4 J (P < 0.01) and 7.5 +/- 3.2 J (P < 0.01) for shocks delivered after 20 seconds of VF with and without a failed first shock, respectively. The mean energy at ED 50 for shocks delivered after 20 seconds of VF with and without a failed first shock was not significantly different (P = 0.53). A strong linear correlation for energy at ED 50 was found between shocks delivered after 10 seconds of VF and shocks delivered after 20 seconds of VF following a failed first shock (r = 0.95, P < 0.01). CONCLUSION: (1) As opposed to monophasic shocks, ED 50 is significantly lower for biphasic shocks delivered after 20 seconds of VF compared with shocks delivered after 10 seconds of VF in pigs. (2) An unsuccessful biphasic shock in pigs does not affect the defibrillation efficacy for a subsequent shock. (3) ED 50 for a biphasic shock delivered after 20 seconds of VF is linearly related to ED 50 for a shock delivered after 10 seconds of VF.

Animals↗