Biomedical subjects

T Eggeling

Publications and source records attributed to T Eggeling.

At least 19 recordsLinked to original sources

PubMed2002

Hiding classical data in multipartite quantum states.

We present a general technique for hiding a classical bit in multipartite quantum states. The hidden bit, encoded in the choice of one of two possible density operators, cannot be recovered by local operations and classical communication without quantum communication. The scheme remains secure if quantum communication is allowed between certain partners, and can be designed for any choice of quantum communication patterns to be secure, but to allow near perfect recovery for all other patterns. No entanglement is needed since the hiding states can be chosen to be separable. A single ebit of prior entanglement is not sufficient to break the scheme.

Journal Article↗

PubMed2001

Distillability via protocols respecting the positivity of partial transpose.

We show that all quantum states that do not have a positive partial transpose are distillable via channels, which preserve the positivity of the partial transpose. The question whether bound entangled states with non-positive partial transpose exist is therefore closely related to the connection between the set of separable superoperators and positive partial transpose-preserving maps.

Journal Article↗

PubMed1995

Management of unstable angina in patients over 75 years old.

BACKGROUND: Although there have been reports of successful percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass grafting (CABG) in elderly patients, few data are available on the optimal management of unstable angina in such patients. This study was therefore designed to identify the preferred revascularization strategy in patients with unstable angina over 75 years of age. METHODS: Early and late results were evaluated for patients over 75 years with unstable angina undergoing PTCA (n = 51) or CABG (n = 53). The two groups were comparable with respect to age, sex distribution, clinical manifestation of symptoms, left ventricular ejection fraction and accompanying non-cardiac diseases. In the CABG group, significantly more patients had left main coronary artery stenosis (13 and 2%, respectively). RESULTS: Both PTCA and CABG treatment showed similar procedural success rates (91 and 94% respectively) and hospital mortality rates (4 and 6% respectively). Procedural complications were comparable regarding Q-wave myocardial infarction, stroke, renal failure and vascular complications. Patients undergoing CABG received significantly more blood transfusions than those undergoing PTCA (17 and 2% respectively). During follow-up, the mortality rate was comparable in both groups (4% with CABG and 8% with PTCA), but significantly fewer patients in the CABG group developed unstable angina (8 versus 21% in the PTCA group), fewer patients were readmitted to hospital for cardiac reasons (CABG group 17%, PTCA group 31%) and fewer patients needed repeat coronary interventions (CABG group 4%, PTCA group 18%). CONCLUSION: Both PTCA and CABG were comparable with regard to short- and long-term mortality, but CABG treatment was favourable with regard to clinical symptoms, readmission to hospital and repeat coronary interventions.

Age Factors↗

PubMed1994

Improved detection of transient myocardial ischemia by a new lead combination: value of bipolar lead Nehb D for Holter monitoring.

The investigations of ST-segment changes by Holter monitoring demonstrate asymptomatic and symptomatic episodes of myocardial ischemia, which may occur during daily activities. One factor, which is of great importance for the detection of silent myocardial ischemia during ambulatory monitoring, is the combination of the leads. Former studies showed that the analysis of two channels alone may not adequately detect silent myocardial ischemia. We therefore used a three-channel ambulatory ECG monitoring system with a new lead combination. The Holter monitoring results were correlated with the distribution of coronary stenosis detected by coronary angiography. In 54 patients with single coronary vessel disease and ischemic ST-segment depressions during exercise testing, standard Holter lead combination CM2/CM5 was extended by a bipolar Nehb D-like lead. Lead combination CM2/CM5 identified 23 patients (43%) with ST-segment depressions (total number of ischemic episodes = 372). Additional Nehb D-like lead identified 30 patients (55%) with ST-segment depressions (total number of ischemic episodes = 1048). The combination of leads CM2/CM5 and Nehb D raised the number of patients with documented ST-segment depressions to 33 of 54 (61%). Lead Nehb D showed the highest sensitivity for the detection of inferior wall ischemia (stenosis of the right coronary artery); nevertheless, this lead may not be regarded as specific for ST-segment alterations only caused by inferior wall ischemia. The correlation of ischemic ST-segment depressions during exercise testing (classified as anterior, inferior, or anterior and inferior type of ischemia) and documented ST-segment changes in the different Holter leads underline these results.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Angiography↗

PubMed1994

Outpatient coronary angiography--safety and feasibility.

The feasibility and safety of outpatient coronary angiography were studied in 2,106 patients. Patients were discharged with a pressure dressing 2 h after the angiographic study. No complications occurred in 99.53% of all patients. Severe complications were seen in 10 patients (0.47%). 9 patients (0.43%) had to be admitted to hospital, either for immediate treatment (4 patients) or due to complications (5 patients). Our results revealed a very low complication rate for outpatient coronary angiography. The number and severity of complications following coronary angiography did not differ significantly between inpatients and outpatients. Therefore, outpatient coronary angiography can be considered as a safe and feasible diagnostic method which may help cut health care costs.

Adult↗

PubMed1994

[Effect of a pressure dressing on angiologic complications after diagnostic coronary angiography].

500 consecutive patients undergoing diagnostic coronary angiography were studied for vascular complications using either a conventional (n = 250) or a special mechanical device for compression dressing (n = 250). In both groups one case of arterial occlusion occurred. Using the conventional pressure dressing, we observed four pseudoaneurysms, whereas there were none in the special mechanical device dressing group (p < 0.05). In contrast, eight patients developed a deep vein thrombosis after mechanical device pressure dressing compared to only 1 venoust in the conventional dressing group (p < 0.02). Five patients, four of the eight patients with mechanical device dressing, suffered from clinical apparent pulmonary embolism (p = 0.1801). Thus, a mechanical device pressure dressing may decrease the number of arterial pseudoaneurysms but is associated with an increased risk of deep vein thrombosis and pulmonary embolism. Therefore, we recommend the use of the mechanical device pressure dressing only in selected patients with severe obesity.

Adult↗

PubMed1994

[Comparison of stress ECG and long-term ECG for detection of myocardial ischemia in patients with coronary heart disease].

Holter-monitoring and exercise-ECG can be employed for the detection of myocardial ischemia. Exercise-ECG is capable of detecting ischemias caused by physical activity. In contrast, Holter monitoring can detect episodes of myocardial ischemia independent of exertion, but possibly connected with other factors such as mental stress. In 60 patients (49 male, 11 female, mean age 55.1 years) with angiographically documented coronary artery disease (26 x 1-vessel, 21 x 2-vessel, 13 x 3-vessel diseases) exercise-ECG and ambulatory 24-h monitoring were performed (3-channel recordings, ST-segment analysis). The assessment of the exercise-ECG showed 31 out of 60 patients with pathological results. 34 patients had pathological ST-segment changes during Holter monitoring (56%). Since both methods detected different patients, a combination of these techniques is useful. The combination of Holter monitoring and exercise-ECG raised the sensitivity to 78% (47/60 patients). Different heart rates were found at the point of maximal ST-segment changes in exercise-ECG as compared to the episodes of ST-segment changes recorded by Holter monitoring. This finding clearly illustrates the fact that different pathophysiological mechanisms are causing myocardial ischemia in respective cases. Using the coronary arteriogram as standard, the sensitivity of the two methods was different. While both techniques could detect multi-vessel disease at a similar level, Holter monitoring was significantly more sensitive in detecting patients with single-vessel disease. Thus, exercise-ECG and Holter monitoring supplement each other in detecting myocardial ischemia. In the future, larger clinical trials will have to confirm these results.

Adult↗

PubMed1993

Quantification of mitral regurgitation by colour flow Doppler imaging--value of the 'proximal isovelocity surface area' method.

In this study 97 patients with mitral regurgitation (age 62 +/- 11 years, 55 men, 42 women) quantified by angiography were studied using colour flow Doppler imaging of isovelocity surface areas in the flow convergence region proximal to the regurgitant orifice. The radii of the proximal isovelocity surface areas for the flow velocities of 28 and 41 cm/s were measured. A flow convergence region was imaged in 100% (96%) of the patients with Grade I/II or more and in 92% (64%) of the patients with Grade I mitral regurgitation for a flow velocity of 28 (41) cm/s. The radii of the proximal isovelocity surface areas correlated significantly with the angiographic grade in patients with sinus rhythm as well as atrial fibrillation. A correct differentiation of Grade I to II from Grade III to IV mitral regurgitation was provided in more than 90% of all patients for both flow velocities investigated. Assuming hemispheric proximal isovelocity surface areas, in 11 patients the regurgitant volumes from echocardiography (range: 2.6-241 (0.9-198) ml for a flow velocity = 28 (41) cm/s) correlated with, but considerably overestimated the values from cardiac catheterization (range: 1.4-72.5 ml) with r = 0.79 (0.82) (P < 0.01) and SEE = 57.9 (42.4) ml for a flow velocity of 28 (41) cm/s. It was concluded that colour flow Doppler imaging of the flow convergence region enables the diagnosis of mitral regurgitation and the differentiation between Grade I to II and Grade III to IV mitral regurgitation, but may be of little value in estimating the regurgitant volume, assuming a hemispheric symmetry of the proximal flow convergence region.

Coronary Angiography↗

PubMed1993

[Long-term electrocardiography in the idiopathic QT syndrome].

The value of long-term electrocardiographic (ECG) monitoring was assessed in 14 patients (8 males, 6 females; mean age 21 [17-30] years) with the idiopathic long QT syndrome (LQTS), 14 healthy subjects of the same age serving as controls. Twelve patients had the typical history of syncopes or sudden cardiac death among family members; seven patients had a history of syncope, while four patients had been successfully resuscitated. None had associated cardiac disease. Among the group with LQTS the rate-corrected QT interval at rest was 498 + 56 ms, in the control group 412 +/- 30 ms (P < 0.005). Resting and maximal heart rates on exercise were similar in the two groups. The rate-corrected QT interval on exercise was significantly longer in the LQTS patients (P < 0.001). In the control group the maximal heart rate in the long-term ECG was significantly higher (144 +/- 28/min) than in the LQTS patients (128 +/- 17/min; P < 0.01). The long-term ECG recorded abnormal findings in five patients: torsade-de-pointes tachycardia in two, T-wave alternans in two, and bradycardia resulting from intermittent sinoatrial block in one. No abnormal findings were recorded in the control group (P < 0.03).

Adolescent↗

PubMed1993

Free skeletal muscle transplantation to an infarction area: an experimental study in the dog.

In plastic surgery, free skeletal muscle flaps are used for treatment of non-healing injuries like chronic osteitis or radiation ulcers. We wanted to evaluate if the neoangiogenesis induced by these flaps can also constitute a method for revascularization in ischemic heart disease. In diffuse small vessel coronary heart disease, patients are not suitable for bypass surgery because it is impossible to create a microanastomosis with the coronary artery. As an alternative, a free striated muscle flap, transplanted onto the heart, can constitute a source of neovessels. With the induction of extra-intracardial collaterals that develop within 4 weeks after transplantation of the flap, a new surgical approach may be offered to those patients. Our experimental work was performed with 20 dogs. In these, a myocardial infarction of the anterior wall was selectively produced using the Judkins-technique (Radiology 89: 815-824, 1967) for injection of Sephadex-microspheres. Four weeks later a free pectoralis muscle flap was transplanted onto the anterior wall of the heart. Arterial blood supply was achieved with an anastomosis with the internal mammary artery. The venous flow was directed into the right atrium. Four to eight weeks after surgery, the patency of the anastomosis was studied by angiography, showing patency in almost all surviving animals. Histological examination of the hearts revealed a prominent vascular network penetrating into the underlying myocardium. Corrosion cast preparations, as well as a postmortem angiography, showed even further penetration of the neovessels into the uninjured parts of the myocardium. Thus, myocardial revascularization may be achieved by transplantation of a skeletal muscle onto the heart.

Anastomosis, Surgical↗

PubMed1993

Pharmacological therapy in coronary heart disease: prevention of life-threatening ventricular tachyarrhythmias and sudden cardiac death.

Life-threatening ventricular tachyarrhythmias are the main reason for sudden cardiac death in coronary heart disease. In the majority of survivors of cardiac arrest, malignant tachyarrhythmias generate from a structurally fixed arrhythmogenic substrate following myocardial infarction without evidence of acute ischaemia. Thrombolysis in acute myocardial infarction improves the electrical stability as elucidated by electrophysiological studies and the signal averaged surface ECG. In post-infarction patients, beta-blockers provide significantly beneficial effects on arrhythmic outcome, particularly in the presence of impaired left ventricular function, whereas calcium antagonists and vasodilators are of no affect or may worsen the prognosis. In survivors of myocardial infarction, the prophylactic use of class I antiarrhythmic agents, which are able to suppress frequent single or complex premature ventricular contractions, cause worsening of the prognosis due to their proarrhythmic properties. However, arrhythmia suppression by antiarrhythmic agents selects patients who are at very low risk for arrhythmic death. Pilot trials using class III antiarrhythmic agents suggest beneficial effect on the reduction of sudden death mortality. As regards secondary prevention of malignant tachyarrhythmias in survivors of ventricular tachycardia or fibrillation, there is controversy about the importance of Holter monitoring or invasive electrophysiological testing in the evaluation of drug efficacy. In patients with severely impaired left ventricular function, pharmacological treatment is of limited efficacy. Even in cases of significant suppression of spontaneous or inducible tachyarrhythmias documented by Holter recording or programmed ventricular stimulation, the arrhythmic outcome is considerably poorer, but it could be influenced by implantable defibrillators. Amiodarone, as a potential alternative to class I antiarrhythmic agents, particularly in patients refractory to conventional antiarrhythmic drugs, shows only limited effects on long-term outcome, which is in part caused by the toxicity of this agent. There is substantial need for new drugs without proarrhythmic properties and particularly for those that correct abnormalities of the automatic nervous system.

Action Potentials↗

PubMed1993

Beat-to-beat variability of ventricular late potentials in the unaveraged high resolution electrocardiogram--effects of antiarrhythmic drugs.

The aim of this study was to assess variability of ventricular late potentials (VLP) in patients with and without inducible ventricular tachycardia (VT), and the effects of antiarrhythmic drugs on VLP variability in the high-resolution electrocardiogram (HRECG). In 27 patients 90 s of unaveraged HRECGs were analysed before and 2 h after oral administration of 200 mg disopyramide, 400 mg mexiletine, 300 mg propafenone and 160 mg DL-sotalol. The duration of the QRS (QRSD) and the duration of the terminal low amplitude signal (LASD) was measured from each beat. Beat-to-beat variability was defined as standard deviation of the differences between consecutive beats. Patients with inducible sustained VT (n = 9) showed higher LASD variability than patients without inducible VT (12.3 vs 9.3 ms.beat-1, P < 0.01). Patients with VLP (n = 17), as defined by the signal averaged ECG, also had higher QRSD and LASD variability (11.8 vs 9.5 ms.beat-1, P < 0.05; 11.5 vs 8.2 ms.beat-1, P < 0.01, respectively) compared to those without VLP. All class I drugs lengthened QRSD and LASD in terms of the absolute values, but only propafenone increased QRSD and LASD variability (9.7 to 12.0 ms.beat-1, P < 0.01; 8.9 to 11.9 ms.beat-1, P < 0.01, respectively). In patients with inducible VT, sotalol decrease LASD variability from 14.3 to 9.3 ms.beat-1 (P < 0.05). We conclude that beat-to-beat VLP variability is increased in patients at a high risk of malignant arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗

PubMed1993

Value of different non-invasive methods for the recognition of arrhythmogenic complications in high-risk patients with sustained ventricular tachycardia during programmed ventricular stimulation.

UNLABELLED: It is well known that patients with coronary heart disease and ventricular tachycardia show a high incidence of arrhythmogenic complications and sudden cardiac death. The best predictor of spontaneous ventricular tachycardia and sudden death in these patients is programmed ventricular stimulation, but this invasive method is limited to specialized institutions. The purpose of our study was to assess the predictive value of Holter monitoring, late potentials and heart rate variability as markers for these high-risk patients. We investigated 20 patients (18 m, 2 f, age range 31-79 years) with coronary artery disease documented angiographically (6 patients with single vessel disease (vd), nine patients with 2 vd, five patients with 3 vd) and previous myocardial infarction. Each patient underwent 24-h ambulatory monitoring with analysis of rhythm of heart rate variability (24-h spectral and non-spectral analysis) and a signal-averaged ECG with late potential measurement. In all patients, sustained ventricular tachycardia was inducible during programmed ventricular stimulation. Late potentials were recorded in 12 out of the 20 patients (60%). Ventricular arrhythmias of Lown classes IVa, IVb or V were recorded in 12 patients. Analysis of heart rate variability compared to 20 age- and sex-matched healthy controls revealed a loss of parasympathic activity and increased sympathic activity in 16 of the 20 patients (80%). CONCLUSION: in this study, heart rate variability was the most sensitive method with which to recognize patients at a high risk of arrhythmogenic complications. Evaluation of the above parameters in large controlled clinical trials may help predict arrhythmogenic complications and sudden cardiac death.

Action Potentials↗

PubMed1993

Magnetocardiography: three-dimensional localization of the origin of ventricular late fields in the signal averaged magnetocardiogram in patients with ventricular late potentials.

The purpose of this study was to detect ventricular late fields recorded by a biomagnetic multichannel system in patients with ventricular late potential and to determine the site of these ventricular late fields non-invasively in three dimensions. Biomagnetic signals of sinus beats during a 5-min acquisition period simultaneously recorded by a 37-channel system Krenikon were averaged in all channels. Ventricular late fields were determined in each channel according to the algorithm of Simson for ECG data. For the localization process, baseline correction from the averaged non-filtered signals was performed at the end of the QRS complex under visual control. The single current dipole model within the homogeneous half-space was applied. Eight patients post myocardial infarction with ventricular late potentials (four with recurrent sustained ventricular tachycardia) and four healthy individuals were examined. In the normal subjects, no ventricular late fields were detected. However, ventricular late fields were found in all patients, and were localized in six patients within the border zone of myocardial infarction. In the four patients with ventricular tachycardia, a spatial coincidence of the site of origin of ventricular late fields and the site of origin of ventricular tachycardia determined by catheter mapping was found in two. It is concluded that magnetocardiography is able to detect ventricular late fields and can be used to determine their site of origin.

Action Potentials↗

PubMed1993

The arrhythmogenic substrate of the long QT syndrome: genetic basis, pathology, and pathophysiologic mechanisms.

The Long QT syndrome (LQTS) is a relatively rare disorder. It has a major clinical impact as affected individuals are prone to syncope and sudden arrhythmogenic cardiac death. The LQTS comprises three groups of patients. The Jervell-Lange-Nielsen syndrome is characterized by an autosomal recessive pattern of inheritance and congenital neural deafness. The Romano-Ward syndrome shows an autosomal dominant pattern of inheritance and normal hearing. Patients with the sporadic form of LQTS have no evidence of familial transmission and have normal hearing. Imbalance of sympathetic cardiac innervation with predominance of the left stellate ganglion and an intrinsic myocardial defect leading to early afterdepolarization are the two pathogenetic mechanisms of LQTS discussed today. More recently a genetic basis for the Romano-Ward LQTS has been reported. The genetic linkage to the Harvey ras-1 gene provides the basis for a new hypothesis that an impairment of guanine nucleotide binding proteins is responsible for symptoms observed in LQTS. This paper discusses the genetic basis, pathology and pathophysiology of LQTS and tries to unify the different theories.

Action Potentials↗

PubMed1993

Local calcification as a determinant of the outcome of excimer laser coronary angioplasty: an in vitro study.

BACKGROUND: Calcification influences the outcome of various angioplasty techniques in the treatment of coronary artery disease. During angioscopic in vitro studies, we observed that dissections and perforations not caused by vessel bending frequently occurred at the boundary areas of plaque and adjacent vessel wall. This study investigated whether this is related to the distribution of calcific deposits. METHODS: Postmortem excimer laser coronary angioplasty (308-nm XeCl) was performed in 51 stenotic coronary arteries. Twenty-three segments were further examined; these consisted of 11 perforations, six dissections, three segments with no ablative effect after the application of 20,000 laser impulses, and three successfully passed stenoses without complications. X-ray diffraction analysis and scanning electron microscopy were performed to detect calcium deposits and their spatial relationship to perforations and dissections. RESULTS: X-ray diffractions analysis detected calcifications in 21 of 23 specimens. Postmortem angiography revealed calcifications only on 11 of 23 segments. Three of 11 perforations were located at the plaque border, as were three of six dissections. In all six complications at the plaque border, x-ray diffraction analysis revealed that the plaque border was identical with a border of calcium deposits. Eight of 11 perforations and three of six dissections could be explained by axis divergence between the laser catheter and the vessel orientation. CONCLUSIONS: Contributing factors for perforations and dissections during excimer laser coronary angioplasty are axis divergence and the distribution of plaque calcification. More sensitive methods are needed to detect local vessel wall calcium in vivo.

Angioplasty, Balloon, Coronary↗

PubMed1993

[The diagnostic value of standard ECG methods, the cold-pressure test and Valsalva maneuver in idiopathic QT syndrome].

The idiopathic Long QT Syndrome is an infrequently occurring disorder. Affected patients usually show ECG alterations and are prone to syncope and sudden arrhythmic cardiac death. Adequate therapy with beta-blocking drugs may significantly improve the prognosis of affected patients. The early and precise diagnosis of the disorder therefore has major prognostic impact. This paper reports the diagnostic significance of standard ECG, exercise stress testing, ambulatory ECG monitoring, cold pressor test and Valsalva maneuver in 14 patients with Long QT Syndrome. The results were compared with those obtained in 14 healthy age matched volunteers. QTc duration was significantly longer in patients with Long QT Syndrome during standard 12-lead ECG at rest (489 +/- 55 ms versus < vs. > 412 +/- 25 ms, p < 0.005), exercise stress test (490 +/- 39 ms vs. 409 +/- 18 ms, p < 0.001), cold pressor test (512 +/- 45 ms vs. 407 +/- 19 ms, p < 0.001), Valsalva maneuver (497 +/- 49 vs. 407 +/- 18 ms, p < 0.001), minimal heart rate during 24-h of ambulatory ECG monitoring (482 +/- 69 ms vs. 402 +/- 22 ms, p < 0.01) and maximal heart rate during Holter monitoring (460 +/- 47 ms vs. 411 +/- 27 ms, p < 0.005). Four of 14 patients with Long QT Syndrome had pathological findings during ambulatory ECG monitoring (two patients showed short episodes of asymptomatic torsade de pointes tachycardia, one patient had an intermittent SA-Block, and one patient showed T-wave alternans). All healthy volunteers had normal ambulatory ECG recordings (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1992

Significance of noninvasive diagnostic techniques in patients with long QT syndrome.

The idiopathic long QT syndrome (LQTS) is an infrequently occurring disorder. Affected patients may have electrocardiographic alterations and are prone to syncope and sudden arrhythmogenic cardiac death. Adequate therapy may improve the prognosis of affected patients significantly. Therefore the early and precise diagnosis of LQTS has major prognostic impact. This study reports the diagnostic significance of standard electrocardiographic techniques and autonomic maneuvers in 14 patients with LQTS. The findings are compared with those of 14 healthy age-matched control persons. QTc duration was significantly longer in patients with LQTS during standard 12-lead electrocardiography (489 +/- 56 vs 412 +/- 30 ms, p < 0.005), exercise stress testing (490 +/- 38 vs 409 +/- 18 ms, p < 0.001), cold pressor testing (512 +/- 45 vs 407 +/- 19 ms, p < 0.001), Valsalva maneuver (497 +/- 49 vs 407 +/- 19 ms, p < 0.001), minimal heart rate during 24-hours of ambulatory electrocardiographic recording (482 +/- 69 vs 402 +/- 22 ms, p < 0.01) and maximal heart rate during Holter monitoring (460 +/- 47 vs 411 +/- 27 ms, p < 0.005). Four of 14 patients with LQTS had pathologic findings during ambulatory electrocardiographic monitoring (2 patients with short episodes of torsades de pointes tachyarrhythmia, 1 patient with intermittent sinoatrial block, and 1 patient with intermittent TU-wave alterations), whereas all control persons had normal ambulatory electrocardiographic recordings (p < 0.05). Thus, noninvasive standard electrocardiographic techniques in combination with autonomic maneuvers may contribute significant information for a precise diagnosis in patients with suspected LQTS.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗