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Biomedical subjects

D Pfeiffer

Publications and source records attributed to D Pfeiffer.

At least 37 records · Page 2Linked to original sources
PubMed2003

Assessment of regional myocardial hypoperfusion with myocardial contrast echocardiography using intravenous bolus application in patients with acute chest pain: a double case report.

Myocardial contrast echocardiography using power Doppler harmonic imaging is able to document myocardial hypoperfusion. Two case reports demonstrate the potential of intravenous bolus application of microbubbles in patients with acute chest pain due to myocardial ischaemia to detect regional low flow conditions. The case reports will focus on the necessity to present Doppler intensity kinetics by Doppler intensity vs time plots or coloured M-modes to present the data more objectively. In addition, the hypoperfusion detected with myocardial contrast echocardiography via bolus injection of microbubbles can only be proven by changes of regional perfusion between repetitive myocardial contrast echocardiography measurements or by additional perfusion analysis, e.g. by scintiscanning.

Acute Disease↗
PubMed2003

Intravenous myocardial contrast echocardiography during angioplasty.

Myocardial contrast echocardiography (MCE) using power Doppler harmonic imaging (PDHI) has been reported to document regional myocardial perfusion. Two case reports demonstrate the potential of intravenous myocardial contrast echocardiography during angioplasty.

Angioplasty, Balloon↗
PubMed2002

[A hemodynamically active type II atrial septal defect in a 78-year-old patient. Indications for interventional catheter occlusion?].

HISTORY AND ADMISSION FINDINGS: A 78-year-old woman presented with a first episode of syncope. She reported increasing fatigue and dyspnoea upon exertion over a period of 20 years and chest pain 2 months prior to admission. Auscultation revealed fixed doubling of the second heart sound. INVESTIGATIONS: Laboratory tests showed increased troponin I. Transaminases were moderately elevated. Chest X-ray showed an enlarged right heart and a dilated pulmonary artery (2 cm). Echocardiography discovered a large secundum atrial septal defect with a diameter of 3 cm but no right to left shunt (no Eisenmenger reaction). Cardiac catheterization revealed a stenosis of the right coronary artery and severe systolic pulmonary hypertension of 80 mmHg. DIAGNOSIS, TREATMENT AND COURSE: A significant stenosis of the right coronary artery was successfully dilated. The ASD was closed by interventional implantation of a commercial closure device (Amplatzer). One month later, echocardiography indicated in an estimated systolic pulmonary pressure of 30 mmHg. The patient's condition improved considerably. CONCLUSION: This case is remarkable in that a very large ASD was asymptomatic up into old age and without the development of an Eisenmenger reaction. Also, large ASD can be by catheterization with the appropriate closure device. Fixed pulmonary hypertension is not obligatory. Non-invasive closure is a good alternative of surgery in elderly patients with risk factors.

Aged↗
PubMed2002

[Long term outcome after percutaneous sclerotherapy of renal cysts with polidocanol].

Methodology and long-term results of treatment of uncomplicated kidney cysts by percutaneous sclerotherapy with polidocanol are presented. Between 1991 and 1998, 132 patients with 151 kidney cysts were treated by percutaneous sclerotherapy with polidocanol as the sclerosing agent. The average volume of the cysts was 288 ml. Over a mean period of 25.8 months, 118 patients with 132 cysts were followed up. In 56% of the cysts treated the cystic cavity disappeared completely, and in 30% the remaining volume was less than 10% of the initial volume. The existing symptoms before intervention remained unchanged only in four (3.4%) patients. The morbidity of the method was 9% and surgical reintervention was not necessary. There was no mortality. The mean hospitalization was 1.06 days. Percutaneous sclerotherapy of uncomplicated kidney cysts with polidocanol offers a high rate of success without the costs and invasiveness associated with laparoscopic surgery and also without the need for repeated interventions associated with sclerotherapy performed with ethanol.

Adult↗
PubMed2002

The Cardiovascular Society in the GDR (German Democratic Republic).

The "Society of Cardiology and Angiology of the German Democratic Republic (GDR)" was the substitute for the "German Cardiac Society" between 1965 and 1992 in Eastern Germany, when the closed borders (since 1961) pevented free private and official communications. The society experienced 12 elections for the board, it had 792 members in 1989, several working groups and organized 14 cardiovascular congresses and hundreds of meetings. The society was very active in education of physicians and assistance personnel and developed an educational program for specialists in cardiology and angiology in 1977. The society supported the foundation of heart centers and the centralized long-term care of patients with heart failure, arrhythmias, congenital defects, pacemakers or peripheral arterial disease. Scientific results as transvasal closure of the ductus arteriosus Botalli, investigations of the energy metabolism of myocardial fibers, endomyocardial biopsy and several drugs, as ajmaline, talinolol, trapidil, PAMBA and hirudin are used up to these days. The tasks of the society ended with the collapse of the GDR in 1989 and therefore the society was liquidated in 1992, when its functions were taken over again by the German Cardiac Society.

Cardiology↗
PubMed2002

GDH biosensor based off-line capillary immunoassay for alkylphenols and their ethoxylates.

The application of a quinoprotein glucose dehydrogenase modified thick-film sensor as label detector in a capillary immunoassay (CIA) for xenoestrogens is presented. The detection of the alkylphenols and their ethoxylates is based on the competition between the analyte and tracer molecules for the binding sites of anti-alkylphenol ethoxylate antibodies. This assay is performed off-line in small disposable PVC capillaries coated with immobilized antibodies. This format allows the combination of the assay with a small portable device potentially useful for on-site environmental monitoring. Beside high amplification the utilization of beta-galactosidase as enzyme label allows the direct combination with a GDH biosensor at optimal pH conditions. The bioelectrocatalytic properties of this biosensor offer an additional amplification and thus allow a very sensitive quantification of 4-aminophenol, generated by the beta-galactosidase. Detection limits of the analytes in the microg/l range were obtained, while other phenolics and surfactants showed no or very little cross reactivity.

Biosensing Techniques↗
PubMed2002

Detection of Escherichia coli in water by culture-based amperometric and luminometric methods.

The application of amperometric biosensor- and chemiluminiscence based methods for rapid detection of viable E. coli in water has been investigated. An amplification of the amperometric signal by a factor of 4 was obtained when the cellobiose dehydrogenase (CDH) biosensor was used instead of a plain graphite electrode for detection of b-galactosidase (b-GAL) activity at 22.5 degrees C. A linear correlation was demonstrated for detection time (DT) vs. initial concentrations (logarithmic units) of E. coli IT1 and E. coli in environmental samples, respectively, by use of the CDH biosensor or a chemiluminometric technique. The study has shown that an E. coli concentration > or = 10(4) cfu/100 mL in environmental samples was determined by the CDH biosensor within one working day. However, further reduction of the DT can be obtained, e.g. by increasing the signal amplification factor using other biosensors.

Biosensing Techniques↗
PubMed2001

Transvenous biventricular defibrillation halves energy requirements in patients.

BACKGROUND: Defibrillation thresholds (DFT) with standard implantable cardioverter-defibrillator leads in the right ventricle (RV) may be determined by weak shock field intensity in the myocardium of the left ventricle (LV). Adding a shocking electrode in a coronary vein on the middle of the LV free wall, thereby establishing biventricular defibrillation, substantially reduced defibrillation requirements in animals. We investigated the feasibility of this approach in 24 patients receiving an implantable cardioverter-defibrillator using a prototype over-the-wire temporary LV defibrillation lead. METHODS AND RESULTS: The LV lead was inserted through the coronary sinus, using a guide catheter and guidewire, into a posterior or lateral coronary vein whose location was determined by retrograde venography. Paired DFT testing compared a standard system (RV to superior vena cava plus can emulator [SVC+Can], 60% tilt biphasic shock) to a system including the LV lead. The biventricular system was tested with a dual-shock waveform (20% tilt monophasic shock from LV-->SVC+Can, then 60% tilt biphasic shock from RV-->SVC+Can). Twenty patients completed DFT testing. Venography and LV lead insertion time was 46+/-40 minutes. The biventricular system reduced mean DFT by 45% (8.9+/-1.1 J versus 4.9+/-0.5 J, P<0.001). Twelve patients (60%) had a standard system DFT >/=8 J, and the biventricular system gave a lower DFT in all patients. There were no adverse events related to the use of the LV lead, which was removed after testing. CONCLUSIONS: Internal defibrillation using a transvenously inserted LV lead is feasible, produces significantly lower DFTs, and seems safe under the conditions tested. Biventricular defibrillation may be a useful option for reducing DFTs or could be added to an LV pacing lead for heart failure.

Coronary Angiography↗
PubMed2001

Investigation of coronary venous anatomy by retrograde venography in patients with malignant ventricular tachycardia.

BACKGROUND: The coronary venous system is increasingly used for left ventricular or biventricular pacing in patients with severe heart failure. The present study investigated the structure of the coronary veins in patients presenting with structural heart disease and malignant ventricular tachyarrhythmias. The availability of veins for possible lead placement was assessed. METHODS AND RESULTS: The number, relative size, and location of coronary veins were evaluated by retrograde venography in 129 patients undergoing cardioverter-defibrillator implantation. Detailed x-ray image analysis was performed in 86 patients, for whom optimal coronary sinus occlusion and vein visualization was achieved. The anterior interventricular vein and the middle cardiac vein were visible in 85 (99%) of 86 patients and in 86 (100%) of 86 patients, respectively. Between these 2 veins, at least 1 additional prominent vein was visible in 85 (99%) of 86 patients. Just 1 vein was present in 44 (51%) of 86 patients. Two veins were observed in 40 (46%) of 86 patients, and >2 veins were visualized in 2 (2%) of 86 patients. Venous anatomy allowed positioning of a 0.014-in guidewire in a coronary vein in 115 (93%) of 124 patients. CONCLUSIONS: The presence, diameter, angulation, and tortuosity of veins as visualized by retrograde venography determine their acceptability for the placement of a lead in a predetermined location. Despite the considerable variability of the coronary venous system among patients, a lateral vessel for lead introduction was available in 82%, and a posterior or lateral vessel was available in 99% of individuals within a patient population that could potentially benefit from a lead on the left ventricle.

Aged↗
PubMed2001

Quinoprotein glucose dehydrogenase modified thick-film electrodes for the amperometric detection of phenolic compounds in flow injection analysis.

The use of thick-film electrodes as basic transducers for highly sensitive amperometric biosensors using PQQ (pyrroloquinoline quinone) dependent glucose dehydrogenase (GDH) with short response times is described. The enzyme is embedded in a polyurethane matrix on top of a platinum based thick film electrode and its ability to reduce oxidized phenolic compounds is exploited. The electrochemical amplification is based on the oxidation of the analyte on the surface of the electrode followed by its enzymatic reduction. Different parameters of the glucose dehydrogenase electrode system using dopamine as a model analyte were optimized, e.g., membrane thickness, pH value, buffer system, flow rate and storage conditions. Using optimized parameters the sensitivity and detection limits for various phenolic compounds were evaluated. The comparison of electrodes from the identical as well as from different batches shows the ability to produce a number of well reproducible sensors showing remarkably small differences with respect to parameters as sensitivity, response times and measuring range.

Acinetobacter calcoaceticus↗
PubMed2001

[Usefulness of a VDD defibrillation electrode in recording atrial electrograms during atrial flutter and atrial fibrillation].

BACKGROUND: Monitoring of atrial signals improves the accuracy in identifying supraventricular tachyarrhythmias to prevent inappropriate therapies in patients with implantable cardioverter-defibrillators (ICD). Since complications due to the additional atrial lead were found in dual chamber ICD systems with 2 leads, we designed a single-pass VDD-lead for use with dual chamber ICDs. PATIENTS AND METHODS: After promising animal experiments in a German multicenter study a prototype VDD lead (single-coil defibrillation electrode with 2 additional fractally coated rings for bipolar sensing in the atrium) was temporarily used in 20 patients. Atrial and ventricular signals were recorded during sinus rhythm, atrial flutter, atrial fibrillation and ventricular tachycardia or ventricular fibrillation. Terminations of ventricular arrhythmias were performed by internal DC shock. RESULTS: The implantation of the electrode was successful in 18 of 20 patients. Mean atrial pacing threshold was 2.45 +/- 0.9 V/0.5 ms, mean atrial impedance was 215 +/- 31 Ohm. Atrial amplitudes were greater during sinus rhythm (2.7 +/- 1.6 mV) than during atrial flutter (1.36 +/- 0.28 mV, p < 0.05) or atrial fibrillation (0.92 +/- 0.29 mV, p < 0.01). During ventricular fibrillation atrial "sinus"-signals had significantly (p < 0.01) lower amplitudes than during sinus rhythm. Mean ventricular sensing was 13.3 +/- 7.9 mV, mean ventricular impedance was 577 +/- 64 Ohm. Defibrillation was successful with 20 J shock. 99.6% of P waves could be detected in sinus rhythm and 85 +/- 9.9% of flutter waves during atrial flutter. During atrial fibrillation 55% of atrial signals could be detected without modification of the signal amplifier. CONCLUSIONS: A new designed VDD dual chamber electrode provides stable detection of atrial and ventricular signals during sinus rhythm and atrial flutter. For reliable detection of atrial fibrillation modifications of the signal amplifier are necessary.

Aged↗
PubMed2001

[Is brain blood supply affected by changes in cardiac volume? Measurements of brain blood supply in healthy subjects during volume overload and in patients with artificial pacemaker by changing the pacing rate].

A constant cerebral blood flow (CBF) in the presence of systemic blood pressure changes and cardiac output (CO) alterations during physiological conditions are postulated by the mechanism of cerebral autoregulation. The aim of the present study is the analysis of CBF in pacemaker (PM) patients with unspecific neurological symptoms. CBF was measured in 9 controls and 23 pacemaker patients with 133xenon, CO using Doppler echocardiography or impedance cardiography. Mean and individual CBF in controls remained unchanged when a CO increase of 28% induced by volume overload was observed. In PM patients a mean CO increase of 38% induced by an increase of basic pacing rate caused different effects of CBF. CBF increased or decreased by about 10% or remained constant. In summary, the data suggest an impairment of cerebrovascular function in those patients with concomittant CBF changes due to CO alterations (15/23 approximately equal to 65%). Thus, the analysis of brain perfusion in PM patients with unspecific neurological symptoms is possibly a new diagnostic feature in the future. It can be discussed whether or not indication and optimizing of pacemaker therapy has to be additionally analyzed by determination of endorgan perfusion.

Adult↗
PubMed2001

Case report: regional cerebral hypoperfusion induced by ventricular tachycardia - short-term hippocampal hypoperfusion and its potential relationship to selective neuronal damage.

BACKGROUND: Focussing on regional cerebral hypoperfusion during hemodynamically stable, but borderline hypotensive, sustained ventricular tachycardia (VT) experimental studies show (1) a reduction of cerebral blood flow (CBF) during tachyarrhythmias in contrast to the concept of CBF autoregulation, (2) a mediation of hypoperfusion by neuronal and humoral mechanisms, and (3) an involvment of microcirculation due to an ischemic stress response of the cerebral tissue. The clinical relevance of these observations remains still unclear. CASE REPORTS: Two patients with coronary artery disease, left ventricular dysfunction and sustained monomorphic VT underwent electrophysiological study. VT was induced and the tracer (99m)Tc-HMPAO was injected after 3 minutes of ongoing VT. Regional CBF during this life threatening arrhythmia was determined with brain SPECT. A scanning protocol was performed after termination of VT. The measurements were repeated at baseline during normofrequent sinus rhythm (SR) one week later. CBF during SR was significantly reduced in the temporal lobe in comparison to the conditions during stable VT, particularly in the left hippocampus. CONCLUSION: The reduction of hippocampal CBF due to cerebrovascular vasoconstriction and neuronal reflex mechanism previously observed in experiments during stable, sustained VT can be confirmed in a clinical scenario by high resolution (99m)Tc-HMPAO brain SPECT. This supports the hypothesis that repetitive stable VT can play a role in the pathophysiology of cerebrovascular insufficiency. Further clinical studies are needed to analyze the impact of tachyarrhythmias on cognitive and mnemic function.

Aged↗
PubMed2001

[Recurrent coumarin necrosis in type II protein S deficiency].

Coumarin necrosis is a rare but clinical very important complication of therapy with coumarin derivatives. We report a patient with congenital protein S deficiency type II, who developed coumarin necrosis during stabilization of phenprocoumon. Diagnostic problems and therapeutic alternatives are discussed considering the recent literature.

Adult↗
PubMed2001

Multicenter experiences with a single lead electrode for dual chamber ICD systems.

Monitoring of atrial signals improves the accuracy in identifying supraventricular tachyarrhythmias to prevent inappropriate therapies in patients with implantable ICDs. Since difficulties due to the additional atrial lead were found in dual chamber ICD systems with two leads, the authors designed a single pass VDD lead for use with dual chamber ICDs. After a successful animal study, the prototype VDD lead (single coil defibrillation lead with two additional fractally coated rings for bipolar sensing in the atrium) was temporarily used in 30 patients during a German multicenter study. Atrial and ventricular signals were recorded during sinus rhythm (SR), atrial flutter, AF, and VT or VF. The implantation of the lead was successful in 27 of 30 patients. Mean atrial pacing threshold was 2.5 +/- 0.9 V/0.5 ms, mean atrial impedance was 213 +/- 31 ohms. Atrial amplitudes were greater during SR (2.7 +/- 1.6 mV) than during atrial flutter (1.46 +/- 0.3 mV, P < 0.05) or AF (0.93 +/- 0.37 mV, P < 0.01). During VF atrial "sinus" signals had significantly (P < 0.01) lower amplitudes (1.4 +/- 0.52 mV) than during SR. The mean ventricular sensing was 13.3 +/- 7.9 mV and mean ventricular impedance was 577 +/- 64 ohms. Defibrillation was successful with a 20-J shock in all patients. In addition, 99.6% of P waves could be detected in SR and 84.4% of flutter waves during atrial flutter. During AF, 56.6% of atrial signals could be detected without modification of the signal amplifier. In conclusion, a new designed VDD dual chamber lead provides stable detection of atrial and ventricular signals during SR and atrial flutter. Reliable detection of atrial signals is possible without modification of the ICD amplifier.

Aged↗