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Biomedical subjects

H Schmidinger

Publications and source records attributed to H Schmidinger.

At least 19 recordsLinked to original sources
PubMed1998

Transjugular intrahepatic portosystemic shunt and cardiac arrhythmias.

The approach to the liver for a transjugular intrahepatic porto-systemic shunt (TIPS) is through the venous system. Because catheter and guidewire system traverses the heart, cardiac arrhythmias may be expected during the procedure. We have prospectively investigated the incidence of such dysrhythmias during TIPS implantation. Twelve consecutive patients, 4 women and 8 men aged 26 to 75 years (mean, 58 +/- 13 years), were studied. Before and on the day of TIPS implantation, a 24-hour Holter recording was performed. Transjugular intrahepatic portosystemic shunt implantation was performed under local anesthesia (lidocaine) and sedoanalgesia (midazolam and fentanyl). None of the patients had concomitant cardiac disease or electrolyte disturbances. In all patients except one, TIPS implantation was successful without any technical complications. A mean of 43 +/- 5.3 hours of Holter recording was performed before and after TIPS implantation. All recordings obtained during this control period were considered inconspicuous. The mean heart rate was significantly higher during the implantation procedure of 136 +/- 37 minutes' duration (83 +/- 20 beats per minute vs 70 +/- 19 beats per minute; p < 0.01). Nine of the 12 patients experienced episodes of nonsustained supraventricular tachycardias, and one patient had two sustained supraventricular tachycardias. Frequent episodes of nonsustained ventricular tachycardias developed in 75% of the patients. It seems clear that TIPS implantation is frequently associated with supraventricular and ventricular tachyarrhythmias even in patients with apparently good cardiac condition at the beginning of the procedure. Thus close cardiac monitoring with resuscitation equipment immediately available throughout the procedure is mandatory.

Adult↗
PubMed1997

The effect of weight reduction on the surface electrocardiogram: a prospective trial in obese children and adolescents.

OBJECTIVE: Controversial data exist on the effect of obesity and weight reduction on surface electrocardiographic parameters. The purpose of this study was to analyze electrocardiograms of obese children in the course of short-term weight reduction. DESIGN: Prospective trial over a period of three weeks with a conventional low calorie diet containing a mean of 525 +/- 109 kcal. SUBJECTS: Thirty-three children, 17 girls and 16 boys with a mean age of 12.2 +/- 1.7 y and an overweight of 25.4-102%, mean 54.2 +/- 15.6%. MEASUREMENTS: Before the onset of therapy and thereafter, body weight, blood chemistry and 12 lead electrocardiographic evaluations were performed. RESULTS: The mean loss of body weight was 5.7 +/- 1.6 kg resulting in a mean decrease in overweight of 13.5 +/- 3.4%. Blood chemistry analyses revealed no significant changes except for cholesterol, triglycerides and uric acid. All electrocardiograms were within normal limits, however, a change in the electrocardiographic pattern was noted after weight loss. Heart rate (84 +/- 14 vs 64 +/- 11 beats per min, P < 0.0001) and QT interval (418 +/- 20 msec vs 391 +/- 22 msec, P < 0.0001) decreased and there was a tendency towards a rightward shift of the frontal plane QRS axis and a leftward shift of the horizontal plane QRS axis. CONCLUSION: Weight reduction in obese children and adolescents is associated with significant changes in the electrocardiographic pattern. These changes may only be detected by intraindividual comparison. Reduction of heart rate and shortening of the QT interval in the course of weight reduction may be of clinical significance by reducing the cardiovascular risk profile, including the risk of potentially fatal arrhythmias in obese subjects.

Adolescent↗
PubMed1997

Effects of lidocaine, ajmaline, and diltiazem on ventricular defibrillation energy requirements in isolated rabbit heart.

The majority of patients with implanted cardioverter defibrillators (ICD) require antiarrhythmic (AR) drugs. ARs may increase defibrillation energy requirements. This study investigated the effects of lidocaine, ajmaline, and diltiazem on ventricular defibrillation energy needs. In 24 isolated rabbit hearts, the 50 and 80% successful defibrillation energy (ED50, ED80) was calculated in four phases: predrug baseline condition (phase 1), and phases 2, 3, and 4 with increasing concentrations of lidocaine, ajmaline, diltiazem (n = 18). Control experiments (n = 6) with only Tyrode's solution infusion indicated that the preparation was stable over time. Defibrillation energy requirements significantly (p < 0.05) increased with all ARs. Low, medium, and high lidocaine concentrations increased ED50 and ED80 to 146, 223, and 312% and 139, 207, and 285%, respectively. Ajmaline increased ED50 and ED80 to 133, 175, and 251% and 135, 208, and 285%, respectively. Diltiazem increased ED50 and ED80 by 175, 236, and 334% and 158, 212, and 286%, respectively. The results of this study demonstrate a dose-dependent increase in defibrillation energy requirements by using lidocaine, diltiazem, and ajmaline. In patients with ICDs, administration of these drugs might cause a critical increase in defibrillation energy requirements, resulting in device failure.

Ajmaline↗
PubMed1996

Implantation of a unipolar cardioverter/defibrillator system under local anaesthesia.

OBJECTIVE: To evaluate prospectively the safety and feasibility of the implantation of cardioverter/defibrillator systems under local anaesthesia. Conventionally, cardioverter/defibrillator systems are implanted under general anaesthesia. With the development of single-lead transvenous unipolar cardioverter/defibrillator systems for subpectoral implantation a pacemaker-like approach for device implantation appears applicable. METHODS: Implantation of a single-lead transvenous unipolar cardioverter/defibrillator under local anaesthesia with sedation for defibrillation threshold testing was performed in 37 consecutive patients. The presenting arrhythmia was ventricular fibrillation in 13 patients, and monomorphic ventricular tachycardia in 24 patients. A 1% lidocaine solution was used for local anaesthesia, and midazolam was applied for sedation to perform defibrillation threshold testing. Arterial blood pressure, arterial oxygen saturation and heart rate were monitored throughout the procedure. The patient's tolerance of the implantation procedure was evaluated with a standardized questionnaire. RESULTS: The unipolar transvenous cardioverter/defibrillator system was implanted successfully in all patients under local anaesthesia. During defibrillation threshold testing, sufficient sedation was achieved with 12.5 +/- 3.7 mg midazolam. For determination of the defibrillation threshold 5.9 +/- 1.4 episodes of ventricular fibrillation were induced. The mean defibrillation threshold was 13.1 +/- 5.5 J, and the mean duration of the implantation procedure was 68 +/- 30 min. Mean heart rate, mean arterial blood pressure and arterial oxygen saturation were not significantly different before and after defibrillation threshold testing. Twenty-six patients (70%) were symptom-free throughout the implantation procedure; most of the remaining patients reported minor symptoms. There were no complications, and patients were discharged 2.2 +/- 0.7 days after implantation. In 12 patients, post-implant testing of the implantable cardioverter/defibrillators was performed successfully, without sedation, 2.8 +/- 1.4 days after as an outpatient procedure. CONCLUSION: Single-lead unipolar transvenous implantable cardioverter/defibrillator systems can be safely implanted under local anaesthesia with mild sedation for defibrillation threshold testing. The procedure is well tolerated.

Aged↗
PubMed1996

Comparison of three cardioverter defibrillator implantation techniques: initial results with transvenous pectoral implantation.

A total of 121 patients underwent epicardial (n = 32), transvenous abdominal (n = 30), and transvenous pectoral (n = 59) ICD implants. Perioperative complications were defined as those occurring within 30 days after surgery. Hospital costs were calculated with $750 per day as a fixed charge. Duration of surgery was the time between the first skin incision and the last skin suture. Severe perioperative complications that were life-threatening or required surgical intervention occurred in the epicardial (6%) and transvenous (10%) abdominal groups, but not in the pectoral group. Perioperative mortality occurred only in the epicardial abdominal group, predominantly in patients with concomitant surgery (18%), and in 5% of patients without concomitant surgery. The duration of surgery was significantly shorter for transvenous pectoral implantation (58 +/- 15 min, P < 0.05) compared to transvenous abdominal implantation (115 +/- 38 min). Epicardial abdominal ICD implantation had the longest procedure time (154 +/- 31 min). The postimplant hospital length of stay was significantly shorter for pectoral implantation (5 +/- 3 days, P < 0.05) compared to transvenous (13 +/- 5) and epicardial (19 +/- 5) abdominal implantation. Total hospitalization costs significantly decreased in the pectoral implantation group ($4,068 +/- $2,099 for the pectoral group vs $14,887 +/- $4,415 and $9,975 +/- $3,657 for the epicardial and the transvenous abdominal group, respectively, P < 0.05). These initial results demonstrate the advantage of transvenous pectoral ICD implantation in terms of perioperative complications, procedure time, hospital length of stay, and hospitalization costs.

Abdominal Muscles↗
PubMed1995

Diurnal variation of ventricular response to atrial fibrillation in patients with advanced heart failure.

Variability of ventricular rate was quantified by two measures of heart rate variability: the SD of the mean R-R interval (SDNN) and the SD of the 5-minute mean R-R interval (SDANN). In 35 patients with atrial fibrillation and advanced heart failure (left ventricular ejection fraction 20% +/- 9%, cardiac index 2.4 +/- 0.7 L/min/m2), SDNN and SDANN were compared to 13 preselected clinical and hemodynamic variables for prediction of outcome. During a 12-month follow-up period, 8 (23%) patients deteriorated clinically; 3 (9%) died, and 5 (14%) underwent heart transplantation. SDNN and SDANN correlated to the difference of the mean R-R interval between night (2 AM to 3 PM) and day (11 AM to noon) with r values of 0.62 and 0.77, respectively. From 15 preselected variables, only SDANN (chi 2 = 6.7, p = 0.01) was independently associated with survival on multivariate analysis. Dichotomized SDANN at 100 msec accurately predicted 12-month survival in 28 (80%) patients (relative risk = 9.77, p = 0.001). In conclusion, analysis of heart rate variability is useful in quantifying diurnal variation of ventricular rate in atrial fibrillation and might be useful in predicting survival in patients with advanced heart failure.

Aged↗
PubMed1995

The impact of implantable cardioverter-defibrillators on mortality among patients on the waiting list for heart transplantation.

Implantable cardioverter-defibrillators were investigated for their impact on mortality in 228 consecutive heart transplant candidates on the waiting list for transplantation (207 patients without and 21 with implantable cardioverter-defibrillator therapy). The mortality rate in 207 patients without implantable cardioverter-defibrillator therapy was 23.2% and in 21 patients with implantable cardioverter-defibrillator therapy was 4.7%. In a Cox proportional hazards model for all 228 study patients (mortality while on the waiting list: 21.5%; transplantation rate: 54.8%), the absence of an implantable cardioverter-defibrillator was only a marginally significant predictor of mortality (p = 0.079). However, the absence of an implantable cardioverter-defibrillator was a powerful predictor of mortality for a subgroup of 134 patients with high-grade ventricular arrhythmias on Holter electrocardiography (mortality while on the waiting list: 26.1%; transplantation rate: 54.5%; p = 0.022) and for a subgroup of 58 survivors of sudden cardiac death (mortality while on the waiting list: 22.4%; transplantation rate: 56.9%; p = 0.018). Implantable cardioverter-defibrillator therapy can be strongly recommended in transplant candidates with a history of sudden cardiac death. Recommendations for an expanded, prophylactic use of implantable cardioverter-defibrillator therapy in heart transplant candidates cannot be given.

Arrhythmias, Cardiac↗
PubMed1995

[Strategies in management of heart transplantation candidates with tachycardic ventricular arrhythmia anamnesis].

We followed up 73 consecutive patients with a history of syncopal ventricular tachyarrhythmias on the waiting list for a heart transplant between 1st March 1992 and 15th September 1994 with the aim of evaluating the impact of implantable cardioverter defibrillator (ICD) on survival. On registration 60 patients were considered fit enough to be ambulant whilst awaiting transplantation. 30 were given ICD therapy (group 1) and 30 were not (group 2). 13 patients required inpatient supervision for ventricular arrhythmias whilst awaiting transplantation, but received no ICD therapy (group 3). The 13 in-patients were in a worse clinical state (NYHA) than the 30 out-patients not given ICD (p < 0.05). With respect to all other clinical and hemodynamic characteristics all groups were comparable. Waiting time for transplantation was also comparable in all groups (n.s., log-rank method). ICD therapy resulted in a significant improvement of survival in these high-risk patients prior to transplantation. Only 1 out of the 30 ICD patients (group 2) and 5 out of the 13 in-patients (group 3) (p < 0.05 log-rank method). During the waiting time group 3 patients were hospitalised longest (p < 0.05), but there was a clear trend that also ICD patients had to be hospitalised to an increased extent (n.s.). Cox multivariate regression analysis of this study population showed that the cardiac index (p = 0.001) and lack of ICD therapy (p = 0.035) were the only independent significant predictors of mortality on the waiting list. ICD therapy had no influence on mortality after transplantation (n.s. log-rank method).

Adult↗
PubMed1994

Adenosine for the management of patients with tachycardias--a new protocol.

We developed a new protocol for diagnosis and treatment of patients with sustained tachycardias (heart rate > 150 beats.min-1). The patients first underwent vagal manoeuvres; if those remained unsuccessful, i.v. adenosine in increasing doses of 6, 12, and 18 mg was administered until sinus rhythm (SR) or transient atrioventricular (AV) block, unmasking the underlying rhythm, was recorded. In the latter and in the non-responding cases other antiarrhythmics were applied. Ninety-three episodes of tachycardia in 46 patients were treated according to this protocol. Six episodes (6%) were terminated by carotid massage, 64 of the remaining 87 episodes (74%) responded to adenosine with return to SR. Conversion to SR occurred more often in episodes with narrow- than in wide-complex tachycardia (81 vs. 59%, P < 0.05). To achieve SR, the mean adenosine dose was lower in narrow- than in wide-complex tachycardia (13 +/- 8 vs 21 +/- 10 mg; P < 0.01). The duration of asystole after adenosine did not differ between these two groups, whereas the duration of arrhythmia after adenosine differed significantly (8.5 +/- 5.8 vs 18.6 +/- 22.9 s; P < 0.05). Side effects of adenosine such as flush, dyspnoea, and chest pain did not seem to be dose dependent and occurred in about 20%. According to our protocol, in more than 75% SR was achieved in patients with sustained tachycardias after vagal manoeuvres and adenosine.

Adenosine↗
PubMed1992

Cardiac involvement in systemic sclerosis.

OBJECTIVE: To assess the incidence and extent of cardiac involvement in systemic sclerosis (SSc) patients with no apparent cardiac symptoms. METHODS: Surface electrocardiography, ambulatory electrocardiography, radionuclide ventriculography, myocardial scintigraphy, and echocardiography were performed in 18 patients. RESULTS: These studies demonstrated ventricular tachycardia in 1 patient, nonsustained ventricular tachycardia in 5, supraventricular tachycardia in 6, decreased left ventricular ejection fraction in 2, decreased right ventricular ejection fraction in 8, and stress-induced reversible myocardial perfusion abnormalities in 6. CONCLUSION: These observations demonstrate a high rate of cardiac abnormalities in SSc patients without cardiac symptoms.

Aged↗
PubMed1992

Antiadrenergic cardiovascular adverse effects of high-dose amiodarone loading regimen.

A 55-year-old patient with inferior wall infarction was treated effectively for ventricular tachycardia with high-dose oral amiodarone loading regimen (5 g within 16 hours). Serial pharmacokinetic studies demonstrated a rapid temporary increase in amiodarone plasma concentration to a maximum of 3.40 micrograms/ml 17 hours after initiation of therapy followed by a return to normal plasma concentration within 8 hours. During fast drug evasion the patient developed acute low-output syndrome with syncope successfully controlled with intravenous catecholamine administration. Our findings suggest that the cardiovascular collapse was caused by the non-competitive adrenoceptor antagonism of amiodarone resulting in secondary autonomic insufficiency.

Administration, Oral↗
PubMed1992

Prognostic value of heart rate variability in patients awaiting cardiac transplantation.

Time and frequency domain parameters of heart rate variability (HRV) were determined in patients with severe endstage heart failure awaiting cardiac transplantation (HTX). These parameters were then correlated with mortality to investigate the performance of HRV in discriminating between groups with high and low risk of death. The standard deviation of five consecutive RR intervals (SDANN) was found to be the parameter with the greatest sensitivity (90%) and specificity (91%). Patients with SDANN values of < 55 msec had a twenty-fold increased risk of death (90% confidence limits: 4-118, P < 0.001). The results furthermore suggest that measurements of HRV are superior to other prognostic markers such as left ventricular ejection fraction, pulmonary artery wedge pressure, cardiac index, and serum sodium levels. We conclude that HRV is a powerful, noninvasive tool to assess the risk of death in candidates for HTX. HRV measurements can therefore be used as a supplement to other markers of risk to determine the optimal therapeutic strategy in patients with severe congestive heart failure.

Adult↗
PubMed1992

[Ventricular tachycardia and ventricular fibrillation. Diagnostic procedure for selection of patients for non-medicamentous therapeutic procedures].

The use of nonpharmacological methods in the treatment of life-threatening ventricular tachyarrhythmias is increasing. These include surgical procedures, the application of direct and radiofrequency current for endocardial ablation, antitachycardia stimulation techniques and the implantation of cardioverter defibrillators. Each of these therapeutical procedures is characterized by its specific indication. Based on the underlying cardiac disease and the characteristics of the electrophysiological properties of the ventricular tachyarrhythmia as well as based on the specific properties of the different nonpharmacological procedures an individual therapeutical approach has to be tailored for a patient given. Primary goal is application of a nonpharmacological procedure exclusively, however, in selected cases additional administration of an anti-arrhythmic drug (decrease in tachycardia frequency in patients with implanted defibrillators, widening of the termination window in patients with antitachycardia devices) may be necessary to achieve satisfactory tachycardia control.

Anti-Arrhythmia Agents↗
PubMed1991

Plasma propafenone concentration in the evaluation of anti-arrhythmic efficacy.

The anti-arrhythmic drug efficacy of oral propafenone therapy (300 mg to 900 mg per day) was studied in relation to propafenone and hydroxy-propafenone plasma concentrations in 70 outpatients (46 males, 24 females, mean age 57 +/- 12 years) followed up for 24 +/- 32 months. On average 1.7 plasma concentration measurements were performed per patient. The arrhythmias were effectively controlled in 32 patients, but in another 32 patients propafenone therapy was ineffective; in six patients the evaluation was unclear. The therapy was effective in 66% of patients with ventricular premature beats, in 50% with complex ventricular arrhythmias, in 40% with ventricular tachycardia and in 20% with supraventricular tachycardia. Fifty per cent of patients with coronary heart disease and electrical disease, but only 20% with dilated cardiomyopathy and Wolff-Parkinson-White syndrome were effectively treated. Measurement of peak plasma propafenone levels performed 4.5 +/- 2 h after oral drug administration revealed no statistically significant dose-plasma concentration relation. Optimal propafenone drug efficacy was documented at propafenone plasma concentrations ranging from 0.20 to 0.60 micrograms/ml (63% of patients considered as effectively treated). There was a trend to decrease propafenone efficacy at plasma concentrations below 0.20 micrograms/ml and above 0.60 micrograms/ml. Analysis of hydroxypropafenone identified four patients as poor metabolizers with unusually high propafenone and low hydroxypropafenone plasma concentrations; only one of these four patients showed drug efficacy. Monitoring of propafenone and hydroxypropafenone plasma concentrations was a practical procedure to assess patient's compliance, to identify poor metabolizers and to guide anti-arrhythmic drug therapy.

Adult↗
PubMed1991

Determinants of subsidiary ventricular pacemaker suppression in man.

To investigate the relative contribution of the duration and rate of overdrive to subsidiary ventricular pacemaker suppression, in six patients with complete heart block after His-bundle ablation, ventricular overdrive stimulation studies were performed. The studies, which were spread over a mean follow-up period of 745 days, were carried out invasively with a temporary lead (one patient) as well as noninvasively with the implanted pacemakers and chest wall inhibition (five patients). The overdrive pacing rate was increased in steps of 10 beats/min, and the pacing duration was 15, 30, 60, 90, and 120 seconds at each level. A recovery period of 2 minutes was allowed after each overdrive stimulation. Incremental ventricular overdrive stimulation at increasing pacing durations consistently caused progressive suppression of ventricular impulse formation. Nonparametric variance analysis demonstrated a significant (P less than 0.0001) influence of both the pacing rate and duration on ventricular recovery time. Nonlinear regression showed an exponential increase in recovery time with incremental pacing rate and a biphasic increase in recovery time with incremental pacing duration. Beyond a pacing duration of 60 seconds ventricular impulse suppression was primarily dependent upon the pacing rate. A nonlinear regression model was applied to predict the number of beats required for return of the escape rhythm toward prepacing control values. The predicted maximum mean number of beats was 15.4 +/- 5.9 and independent of the rate and duration of pacing, although, the initial temporary instability of the escape rhythm was directly related to the degree of overdrive.

Adult↗
PubMed1989

24 hours electrocardiographic monitoring in obese children and adolescents during a 3 weeks low calorie diet (500 kcal).

Twenty-four hour electrographic recordings were made on 36 grossly obese children and adolescents during a 3-week weight reduction regimen with a 525 kcal (2196 kj) mixed diet at weekly intervals. One hundred and ten Holter ECGs were analysed. Weight loss during the treatment was calculated to be 5.7 +/- 1.6 kg. Average and minimal heart rate decreased constantly throughout the study period from 83.9 +/- 9 to 75 +/- 9/min and 53 +/- 6 to 45 +/- 6/min, respectively (P less than 0.01, P less than 0.005). During the second week maximal heart rate increased significantly but returned to baseline values in the third week. Neither before nor during the period of therapy were any dysrhythmias monitored. Dietary regimens containing 500-700 kcal, based on a mixed composition of foods with sufficient amounts of minerals, can be regarded as a safe therapeutic tool in the treatment of obese children and adolescents.

Adolescent↗