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Biomedical subjects

L Kappenberger

Publications and source records attributed to L Kappenberger.

At least 55 records · Page 3Linked to original sources
PubMed1999

Recurrent cardioembolic stroke related to late dislodgement of a right atrial pacing lead into the left atrium.

A 76-year-old woman had a permanent transvenous DDDR pacemaker implanted for complete atrioventricular block. She was hospitalized 4 years later for recurrent transient ischaemic attacks related to dislodgment of the atrial lead into the left atrium through a patent foramen ovale. The patient was successfuly treated by transvenous extraction of the atrial lead. The follow-up has been uneventful 12 months after the procedure. Left atrially dislodged pacemaker leads have to be retracted under full anticoagulation.

Aged↗
PubMed1999

The chick embryo heart as an experimental setup for the assessment of myocardial remodeling induced by pacing.

The mechanisms regulating remodeling of the heart are not well understood and only rarely investigated for pacing. We therefore developed a model based on the well-established chick embryo heart preparation. Hamburger Hamilton 21 stage Leghorn chick embryos were used. Access to the heart was obtained after having dissected the shell membranes. The electrodes (platinum wires) were placed in ovo: the anode on the vitelline membrane and the cathode at different sites of the heart (sinus venosus, base/apex of the ventricle). Sensing and stimulation thresholds were measured. Survival of the paced chick was studied. Among 30 chick embryonic hearts, the stimulation thresholds were 1.4 mV +/- 0.5 SD for the atrium, 2.6 V +/- 1.4 SD at the base, and 3.2 V +/- 1.5 SD at the apex of the ventricle, while the sensing signals were 1.3 mV +/- 0.5 SD at the atrium, 19.6 mV +/- 4.1 SD at the base, and 21.6 mV +/- 3.9 SD at the apex of the ventricle. Continuous pacing (pacing rate = intrinsic rate + 10%) could be maintained for 1.5 hours +/- 0.5 SD at the atrium, 8.9 hours +/- 0.7 SD at the base of the ventricle, and 7.9 hours +/- 1 SD at the apex of the ventricle up to death of the embryos. By using intermittent electrical stimulation, the association of 5 minutes on/5 minutes off pattern during 18 hours and 5 minutes on/15 minutes off, during 30 hours resulted in an effective pacing period of 19 hours in 60% of the experiments, reflecting 15 cell turnover cycles. This experimental setup will allow the study of morphological, metabolic, and molecular bases of ventricular remodeling induced by electrical stimulation.

Animals↗
PubMed1999

Electronic monitoring of compliance to lipid-lowering therapy in clinical practice.

Nonadherence to treatment is a common problem in the clinical management of hypercholesterolemic patients. This study was carried out with the aim of monitoring the daily compliance to a 6-month course of lipid-lowering therapy, using a microelectronic device, the Medication Event Monitoring System (MEMS), versus pill count. Forty men with primary hypercholesterolemia were prescribed fluvastatin 1 x 40 mg daily, provided in a MEMS package to record the date and time of each opening of the pillbox. Thirty-nine of 40 patients (98%) completed the study. Total cholesterol and LDL cholesterol levels decreased significantly (18% and 25%, p < 0.001) during the 6-month therapy period. A high mean rate of compliance was achieved by MEMS using the following three indexes--compliance to total prescribed dose (88.8% +/- 13.5%), compliance to prescribed days (82.4% +/- 19.5%), and compliance to prescribed time of day (81.86% +/- 19.5%)--and by pill count (93.4% +/- 9.5%). In addition, the MEMS provided some patterns of nonadherence to medication, undetectable by pill count alone, such as a drug holiday in 38% of cases, a drug omission for more than 7 consecutive days in 9% of cases, and, conversely, use of more than the one prescribed daily dose in 47% of cases. A significant correlation between the rate of compliance and the decrease in LDL cholesterol was observed only when the compliance was assessed by MEMS. The results indicate that MEMS is a useful tool for monitoring compliance in clinical practice and may possibly increase adherence to long-term lipid-lowering therapy.

Adult↗
PubMed1999

Pacing-induced ventricular remodeling in the chick embryonic heart.

Chronic ectopic pacing in the adult heart induces myocardial hypotrophy close to the pacing site. We have recently described a similar localized decrease of compact myocardium thickness in the chick embryonic heart after 48 h of intermittent apical ventricular pacing. Here we analyze the cellular mechanisms underlying the response of the embryonic heart to pacing. Because the developing heart had been found to adjust its morphology according to functional demands by undergoing cellular hyperplasia or hypoplasia, we hypothesized that the stimulation should result in hypoplasia of the apical ventricular compartment. Morphologic analysis of hearts submitted to 18 h of effective pacing during 48 h showed a mild to moderate ventricular dilatation, a 28% decrease in the apical compact layer thickness with no changes in other ventricular locations, and atrial wall thickening. These modifications were caused by changes in the number of cell layers, whereas cell size was similar between paced and control hearts. Analysis of proliferative activity after 24 h of pacing showed a decrease of 32% in the rate of cell proliferation limited to the apical compact layer exposed to stimulation. No ultrastructural injury or increased cell death was found. These changes were accompanied by down-regulation of the myocardial growth factor fibroblast growth factor-2 but no differences were found in the expression of platelet-derived growth factor. Thus, chronic intermittent ventricular pacing induces myocardial remodeling in the chick embryonic heart, on the basis of locally regulated rates of cell proliferation.

Animals↗
PubMed1999

[Cardiac pacing. Percutaneous extraction of infected pacing catheter].

Infection of a cardiac pacemaker is a rare but serious complication. Percutaneous ablation of the pacemaker and pacing catheter is the only effective treatment. Techniques of extraction of pacing systems have been evaluated but the long term results require analysis. Eighteen patients with infection of cardiac pacemakers underwent extraction of one or more pacing catheters (14 atrial and 20 ventricular) in one same centre. The indication was infection of the pacemaker unit (12 cases) or septicaemia (6 cases) The causal organism was a staphylococcus (aureus: 7 cases, epidermidis: 10 cases, capitis: 1 case). Three techniques were used: 1) direct external manual traction, 2) internal traction with several devices, 3) endovascular counter-traction (Byrd-Cook system). The time from primary implantation of the pacing catheter to its extraction was 42 months and from last pacemaker manipulation to infection, 23 months. The average duration of the extraction procedure was 120 +/- 45 minutes; that of fluoroscopy was 10 +/- 6 minutes. The first technique was used 12 times, the second 8 times and the third 14 times, with complete extraction of the catheter in 88.2% of cases. The metallic tip of the distal electrode embolised in 2 cases and remained stuck in the right ventricle in 1 case. Only one pacing catheter was abandoned. After an average follow-up of 45 months, none of the patients had recurrent infection or any other complication. The authors conclude that extraction of infected pacing catheters is safe and effective. It is the treatment of choice of this complication.

Aged↗
PubMed1998

An echocardiographic and magnetic resonance imaging comparative study of right ventricular volume determination.

Assessment of right ventricular volume and function is important in many clinical settings involving heart or lung disease. However, the complexity of the right ventricular anatomy has prevented accurate volume determination by two-dimensional echocardiography. In the present study, 5 models incorporating standard echocardiographic views, were used to determine right ventricular volume in 10 human subjects. Two models were contingent on the true crescentic appearance of the right ventricle, whereas the remaining 3 calculated the right ventricular volume as a pyramid, an ellipsoid or other tapering geometrical figures, respectively. Subsequently, echocardiographic right ventricular volumes were compared to magnetic resonance imaging derived volumes. Correlation analysis and agreement measurement between the echocardiographic and magnetic resonance end-diastolic volume were performed in 10 out of 10 subjects and in 9 out of 10 subjects for the end-systolic volume. The 2 crescentic models resulted in the most reliable estimation of right ventricular volume. Those findings suggest that models based on right ventricular anatomical landmarks are feasible and should be preferred in echocardiographic studies.

Adult↗
PubMed1998

A computer model of cardiac electrical activity for the simulation of arrhythmias.

Modern computer power allows development of models of the heart that may be helpful for the understanding of arrhythmia mechanisms if, based on realistic physiological parameters, such models can display phenomena difficult to study in nature. Therefore, a two-dimensional model of the cardiac tissue has been implemented, where the modeling of each cell is based on membrane ionic channels (Beeler-Reuter and Luo-Rudy models). In addition, an ECG was computed based on the ionic currents simulated. This model allows us to observe the propagation of the action potentials Vm across the cardiac tissue, the evolution of Vm for any of the cardiac cells, and the underlying ionic currents. The computation of the ECG makes it possible to relate this information with an often-used diagnostic tool. Simulations of normal and pathological phenomena such as functional and anatomic reentry have been performed. Our simulation results show that the applied computer model based on ionic currents seems accurate and realistic when compared with biological models and offers a new approach to study the origin, prevention, and termination of arrhythmias.

Action Potentials↗
PubMed1998

Endoluminal vessel reconstruction by stent placement in patients with obstructive coronary artery disease who are poor surgical candidates.

OBJECTIVE: To investigate the safety and efficacy of endoluminal vessel reconstruction by intracoronary stenting in patients with single or multivessel disease who have been turned down for surgical revascularisation. DESIGN: An observational, single centre trial of consecutive patients being followed up clinically. SETTING: Tertiary referral centre. PATIENTS: 43 patients treated between 1995 and 1996 with a clinical follow up period of at least six months. MAIN OUTCOME MEASURES: Acute procedural success following intervention (defined as a residual stenosis of < 30% with normal antegrade flow and without acute clinical complications); major adverse clinical events (death, myocardial infarction, repeat intervention, clinical restenosis); and functional status during follow up. RESULTS: Acute procedural success was achieved in 39 patients. Failures resulted from a refractory no reflow phenomenon with Q wave myocardial infarction (two patients), and from subacute stent thrombosis (one patient) and saphenous vein graft rupture at stent site (one patient), both manifesting by non-Q wave myocardial infarction. During a follow up period of 17 (8) months (mean (SD)), three of these patients died. Clinical restenosis was treated by repeat percutaneous intervention in 11 patients, while 28 patients remained asymptomatic. On a Kaplan-Meier estimate, the proportion of patients without adverse clinical events at two years was 65%. CONCLUSIONS: Percutaneous reconstruction of diseased coronary arteries in patients with single or multivessel disease turned down for surgical revascularisation may be considered as a valuable treatment option. On follow up, more events seem to be encountered than after elective de novo stenting of discrete coronary lesions. This is probably related to higher clinical restenosis rates.

Aged↗
PubMed1998

[Percutaneous versus surgical revascularization of isolated lesions of the proximal anterior interventricular artery. Five-year follow-up of a prospective randomized study].

The authors report the results of 5 years follow-up of 134 patients who benefited from percutaneous transluminal coronary angioplasty 5PTCA) or surgical intervention with implantation of the internal mammary artery as treatment of an isolated lesions of the proximal left anterior descending artery with normal left ventricular function. Sixty-eight patients underwent PTCA (group 1) and 66 had surgical bypass (group 2). The demographic data of the two groups was comparable. The incidence of the following events was analysed: death, myocardial infarction, indication for further revascularisation and functional class. At 5 years, the global mortality was 6% (8% in group 1 and 2% in group 2) but cardiac mortality was only 1% (1 patient in each group). The cumulative incidence of myocardial infarction was higher after angioplasty (15% vs 5%) but was mainly related to acute occlusions or acute coronary syndromes during angioplasty. However, the incidence of Q wave infarction was similar in the two groups. During follow-up, 32 patients (26 in group 1 and 6 in group 2) required one or more additional revascularisation procedures of the left anterior descending or of another artery. The proportion of asymptomatic patients at 5 years was high and similar in both groups. Finally, the proportion of patients without events during follow-up was 56% in group 1 and 86% in group 2. Despite the risk of restenosis and reoperation associated with angioplasty, this technique is an acceptable therapeutic alternative to surgical revascularisation in patients with isolated stenosis of the left anterior descending artery. Therefore, the therapeutic decision depends on the individual case, the availability of treatment and the patient's preference during consultation.

Angioplasty, Balloon, Coronary↗
PubMed1997

[Sudden death in hypertrophic obstructive and non-obstructive cardiomyopathy: can it be prevented?].

Sudden cardiac death constitutes the most devastating aspect of obstructive and non-obstructive hypertrophic cardiomyopathy. Loss of consciousness and family history of sudden cardiac death should alert the physician to the risk of sudden death. ECG, morphological and hemodynamic assessment, and exploration of central nervous activity are of little use in stratifying the risk of sudden cardiac death. Loss of consciousness associated with nonsustained ventricular tachycardia and inducible sustained ventricular arrhythmia identify patients at very high risk of sudden cardiac death. Nevertheless, many variable factors are involved in the pathophysiology of sudden cardiac death, and hence risk stratification of sudden cardiac death in patients with hypertrophic cardiomyopathy remains a very difficult clinical challenge.

Adolescent↗
PubMed1997

[Follow-up after heart transplantation].

The prognosis of patients with end-stage cardiac disease has dramatically changed with transplantation. The incidence of complications remains relatively high and needs a very careful follow-up to have good long term results.

Coronary Disease↗
PubMed1997

[Diastolic dysfunction of the left ventricle: from physiopathology to treatment].

Our understanding of cardiac failure has greatly changed over the last 15 years. Left ventricular diastolic dysfunction, which is now recognised as one of the primary causes of certain types of cardiac failure (1). Abnormal left ventricular diastolic function is the common determinant and indeed the earliest sign of all chronic left ventricular failures whether systolic left ventricular dysfunction is associated with it or not (2). In this paper, we review the basis of diastolic dysfunction and its impact on diagnosis and treatment of cardiac failure.

Aged↗
PubMed1997

The effect of simvastatin on progression of coronary artery disease. The Multicenter coronary Intervention Study (CIS).

BACKGROUND: In several angiographic trials, HMG-CoA reductase inhibitors have shown a beneficial effect on the progression of coronary artery disease. Using 20 mg simvastatin, day-1, a treatment period of up to 4 years was necessary to show a significant reduction in coronary artery disease progression. The question remains however whether higher dosages of simvastatin would be more advantageous in respect to the magnitude of the effect and the required time interval to demonstrate treatment efficacy. METHODS AND RESULTS: In the Coronary Intervention Study (CIS), a multicentre randomized double-blind placebo-controlled study, the effects of lipid-lowering therapy with simvastatin on progression of coronary artery disease in 254 men with documented coronary artery disease and hypercholesterolaemia were investigated. Following a period of lipid-lowering diet, treatment with 40 mg simvastatin or placebo was maintained for an average of 2.3 years. Two primary angiographic endpoints were chosen: the global change score (visual evaluation according to the method of Blankenhorn) and the per patient mean change of minimum lumen diameter (evaluated by the CAAS I system). The mean simvastatin dose was 34.5 mg day-1. In the placebo group, the serum lipids remained unchanged; in comparison to the placebo group the simvastatin group showed a 35% LDL-cholesterol decrease. Coronary angiography was repeated in 205 patients (81%) and 203 film pairs (80%,) were evaluable by quantitative coronary angiography. In the simvastatin and placebo groups, the mean global change scores were +0.20 and +0.58 respectively, demonstrating a significantly slower progression of coronary artery disease in the treatment group (P = 0.02). The change in minimum lumen diameter assessed by computer-assisted quantitative evaluation with the CAAS I system was -0.02 mm in the simvastatin group and -0.10 mm in the placebo group (P = 0.002). In the simvastatin group, there was a significant correlation between the LDL cholesterol levels achieved therapeutically and the per patient mean loss of minimum lumen diameter (r = 0.29; P = 0.003). During the study period, there was no significant difference in the incidence of serious cardiac events (15 of 129 patients in the simvastatin group and 19 of 125 patients in the placebo group, ns). CONCLUSION: Treatment with 40 mg simvastatin day-1 reduces serum cholesterol and slows the progression of coronary artery disease significantly within a short period of treatment time. In the treatment group, retardation of progression is inversely correlated to the LDL-cholesterol levels achieved.

Adult↗