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.

Die peripartale Kardiomyopathie?der (un)bekannte geburtshilflich-kardiologische Notfall

Peripartum cardiomyopathy (PPCM) is rare cardiac complication afflicting women during pregnancy or until 5 months post partum with the typical signs of acute cardiac failure. PPCM is similar to dilated cardiomyopathy (DCM) in terms of symptoms, histopathology and treatment but is characterized by a better outcome with a high rate of spontaneous normalization of left-ventricular size and function. The understanding of the etiology is limited. However, viral myocarditis and autoimmune factors might be involved in the development of PPCM. Clinically, PPCM shows pulmonary symptoms such as dyspnea, tachypnea and coughing. The diagnosis is finally established by echocardiography. It has to be assumed that PPCM is often undetected or misdiagnosed because of the low incidence, the unspecific symptoms and the fact that other pregnancy-related factors have similar clinical appearance. The treatment is also unspecific and similar to DCM and acute cardiac failure. The severity of the disease requires an interdisciplinary approach in a perinatal center with consequent follow-up of the patients for risk stratification including echocardiography.

Myocardial contrast echocardiography for assessment of myocardial perfusion at rest in a patient with left main coronary artery stenosis

The present case will focus on the potential of hypoperfusion detection with myocardial contrast echocardiography (MCE) using power Doppler harmonic imaging (PDHI). PDHI is normally performed in a triggered mode. Microbubbles were destroyed by the ultrasound energy in the myocardium, and myocardium has to be refilled with microbubbles within the time interval between the ultrasound pulses to obtain repetitive information about perfusion. Using the contrast agent Levovist, however, real-time PDHI also results in myocardial opacification presumably due to perfusion signals of the arteriolar microbubble passage. A 45-year-old woman with typical stress-induced angina was admitted to our department for cardiac catheterization. Prior to the angiography a conventional echocardiogram showed normal left ventricular function. Tissue Doppler, however, demonstrated postsystolic longitudinal shortening of the septal, anterior, and lateral wall regions. Myocardial contrast echocardiography with triggered PDHI showed complete opacification of the myocardium at rest. Using real-time PDHI with Levovist, the septum could not be opacified. The consecutive angiography documented a severe unprotected main coronary artery stenosis. After angioplasty and stent implantation, MCE measurements were repeated. Repetitive intravenous bolus injections of Optison during triggered PDHI showed no differences to the investigation prior to the angioplasty. Using real-time PDHI with Levovist, however, there was a marked difference in comparison to the pre-interventional analysis. A complete opacification of the apical septum was observed. The present case suggests that different MCE techniques can analyze different compartments of the myocardial vasculature in clinical practice. This methodological comparison between triggered and real-time PDHI shows obviously differences in the DI signal detection due to the different microbubble behavior. Clinicians should be aware of the potentials of MCE to improve noninvasive diagnostic procedures in patients with ischemic heart disease.

Die antegrade Sklerotherapie der Varicocele testis?M�gliche und vermeidbare Komplikationen

Antegrade sclerotherapy is an established procedure for the treatment of varicocele. To avoid complications during the dissection of the pampiniform plexus, detailed knowledge of the angioarchitecture of the spermatic cord is recommended. One group of plexus veins is situated ventrolaterally and is surrounded by a yellowish fat which serves as a landmark. This vein group should be chosen for preparation. Phlebography of the internal testicular vein is mandatory. If arteries or major pelvic veins become visible while applying contrast media, sclerotherapy should not be performed. Paravasation of sclerosing agent has to be recognized and treated immediately to prevent deleterious effects.

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.

Chronic regulation of the expression of the gap junction protein connexin 43 in transfected HeLa cells

Gap junction channels are essential for intercellular communication. Among the most abundant gap junction channel proteins is connexin 43 (Cx43). The goal of our study was to find out, whether Cx43 content may be regulated via adenylyl cyclase (AC)/cAMP/protein kinase A (PKA), protein kinase C (PKC) pathways or by a tyrosine kinase coupled pathway, i.e. TNF alpha-receptor dependent pathway. Therefore, we used HeLa cells transfected with Cx43 and exposed these cells for 24 h to either db-cAMP (10(-4)M), forskolin (10(-5)M), the phorbolester phorbol-12,13-didecanoate PDD (10(-7)M) (or its inactive form 4 alpha-PDD), TNF alpha (10 U/ml) with or without additional treatment with the MAP kinase inhibitors SB203580 (10(-5) M, p38 MAP-kinase inhibitor) or the MEK1-inhibitor PD98059 (10(-5)M). Cx43 content was analysed using Western blot analysis. All results were confirmed by a second series of identical experiments using Cx43 immunohistochemistry. We found significantly enhanced Cx43 content in cells treated with db-cAMP, forskolin, PDD or TNF alpha (p<0.05), while 4 alpha-PDD or the solvent DMSO exerted no effect. These increases in Cx43 content could be completely suppressed by SB203580 (p<0.05) but not by PD98059. In absence of a stimulating drug, these inhibitors (SB203580 or PD98059) did not affect Cx43 content. Additional PCR experiments revealed increases in Cx43-mRNA under the influence of db-cAMP, forskolin, PDD or TNFalpha (p<0.05), which all could be completely suppressed by SB203580. From these results we conclude that 1.Cx43 content can be regulated via AC/cAMP/PKA, PKC and TNF alpha-receptor-dependent pathways 2. Activation of p38 MAP kinase is a common pathway for regulation of Cx43 content in HeLa cells

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.

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.

[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.

[Atrial fibrillation in pacemaker therapy: physiologic versus VVI pacing]

Recent prospective trials of pacing in atrial fibrillation are inconclusive. A substantial suppression of atrial tachyarrhythmias has been observed in patients with brady-tachy-syndrome and high rate of paced vs. intrinsic beats. An improvement in prognosis, incidence of thromboembolism, rehospitalization and improvement in heart failure have been controversally described in different trials. The quality of life improves in most studies in physiologic pacing. This paper presents a short overview on published and ongoing trials in pacing of atrial fibrillation.

[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.

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.

Surgical management of complications caused by transcatheter ASD closure

BACKGROUND

Transcatheter occlusion of uncomplicated atrial septum defects (ASD) is recognized as an effective and minimally invasive method. Sometimes, serious early and late complications require surgical intervention. We therefore investigated reasons and outcomes of the secondary surgical approach.

METHODS

5 patients (aged 5-73 yrs) were admitted to our institution for device explantation and surgical ASD closure. ASDOS devices (A devices) had to be explanted in 4 patients and a SIDERIS "buttoned" occluder (S device) had to be explanted in 1 patient. The period from transcatheter implantation to surgical explantation ranged from 1 hour to 3 years.

RESULTS

3 patients (60 %) had to be operated in an emergency setting. In our youngest patient (5 yrs), the A device separated and embolized into the aorta and pulmonary artery. A pregnant women who needed emergent cesarean section developed hemopericard and tamponade due to atrial perforation by a fractured leg of an A device. In another A device, a suspect endocarditis caused membrane perforation. Malpositioning of an S device was the reason for operation. All patients recovered well without neurological symptoms.

CONCLUSIONS

Transcatheter closure of uncomplicated ASD is a feasible alternative but surgical stand-by is essential. Nevertheless more complicated ASD should be operated, especially since the cosmetically satisfactory techniques of minimal invasive heart surgery are available.

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.

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.

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.

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.

Effects of mild hypothermia on metabolic disturbances in fetal hippocampal slices after oxygen/glucose deprivation depend on depth and time delay of cooling

OBJECTIVE

There is increasing evidence from animal experiments that mild hypothermia induced during or after cerebral ischemia might protect the immature brain from neuronal cell damage. However, the exact interrelation between the postischemic time delay and the degree of mild hypothermia by which to achieve neuroprotective effects on ischemic insults of different severity has not yet been elucidated systematically. To determine optimal neuroprotection, we studied the interaction between these variables in a recently modified hippocampal slice model.

METHODS

We investigated the recovery of energy metabolism and protein synthesis (PSR) in hippocampal slices from mature fetal guinea pigs after 20, 30, or 40 minutes of oxygen and glucose deprivation (OGD). Hypothermia of varying degrees was induced immediately or 2 or 4 hours after OGD and lasted for 12 hours. Prolonged inhibition of PSR after ischemia has been shown to be a sensitive marker of neuronal cell damage.

RESULTS

Hypothermia initiated immediately after OGD significantly improved the recovery of energy metabolism and PSR. If there was a 2-hour delay in the onset of hypothermia, neuroprotection depended on the degree of hypothermia. Reduction of the incubation temperature to 31C diminished the disturbances of energy metabolism and PSR, whereas lowering the bath temperature to only 34C was not effective. Hypothermia induced 4 hours after OGD did not have any influence on the recovery of energy metabolism and PSR.

CONCLUSION

We conclude that the effects of mild hypothermia on metabolic disturbances in hippocampal slices of mature fetal guinea pigs depended on the intervention delay and the degree of cooling. The shorter the postischemic intervention delay and the greater the degree of hypothermia, the better the neuroprotective effect seems to be.

Circulatory responses to acute asphyxia are not affected by the glutamate antagonist lubeluzole in fetal sheep near term

OBJECTIVE

Asphyxia is one of the main causes of perinatal brain damage that can result in psychomotor deficits during later development. Recently lubeluzole, a new glutamate antagonist, was shown to improve clinical outcome considerably without any safety concerns in adults who had acute ischemic stroke. However, our preliminary experiments showed transient alterations in heart rate as well as arterial hypertension after intravenous application of this compound in fetal sheep. The aim of the present study was to examine in detail whether lubeluzole affects circulatory responses to acute asphyxia in fetal sheep near term.

METHODS

Eleven fetal sheep were chronically instrumented at a mean gestational age of 133 +/- 2 days (term is at 147 days). The fetuses in the study group (n = 6) received three bolus injections of lubeluzole at 30-minute intervals (3 x 0.11 mg/kg estimated body weight), and five controls received solvent. Organ blood flows and physiologic variables were measured before, during, and after arrest of uterine blood flow for 2 minutes (ie, at 0, 1, 2, 3, 4, and 30 minutes).

RESULTS

Before asphyxia, distribution of combined ventricular output and physiologic variables in fetuses from the control group were in the normal range for chronically prepared fetal sheep near term. During acute asphyxia there was a redistribution of cardiac output toward the central organs accompanied by pronounced bradycardia and progressive increase in arterial blood pressure. There were nearly no differences between groups in the time course of physiologic and cardiovascular variables measured before, during, and after acute intrauterine asphyxia.

CONCLUSION

Lubeluzole did not affect circulatory responses to acute asphyxia in fetal sheep near term.

[Catheter ablation of supraventricular tachyarrhythmias]

The term "supraventricular tachyarrhythmia" summarizes electrophysiologically different arrhythmias. After detection of the mechanism of the present arrhythmia, the weak part of the reentrant circuit has to be identified using different mapping techniques. The catheter ablation is widely used as focal ablation (sinus tachycardia, ectopic atrial tachycardia, focal atrial fibrillation) or for interruption of conducting pathways (accessory pathways, AV nodal reentrant tachycardia). A single ablation line should be created in isthmus-dependent atrial flutter or in incisional tachycardias, which is less used now-a-days. Multiple ablation lines are needed for ablation of atrial fibrillation, which is a method investigated in arrhythmia centers only. Some arrhythmias are less well understood, not localizable and therefore not curatively treated with ablation techniques. Newer three-dimensional mapping methods may help in this situation. The challenge at the present time is the catheter ablation of atrial fibrillation.

Organolanthanide-catalyzed cyclization/boration of 1,5- and 1,6-Dienes

[figure: see text] 1,5- and 1,6-Dienes undergo a cyclization/boration reaction in the presence of a catalytic amount of Cp*2Sm.THF. The resulting organoboranes can be oxidized to the corresponding primary cyclic alcohols using standard conditions.

[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.

[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.

Coagulation, fibrinolysis and platelet P-selectin expression in peripheral vascular disease

OBJECTIVES

to examine coagulation, fibrinolysis, and platelet activity in patients with peripheral vascular disease (PVD).

DESIGN

fifty consecutive PVD patients and 50 healthy volunteers. (Prospective comparative study.)

MATERIALS AND METHODS

P-selectin expression in non-fixed, whole blood was measured flow cytometrically on non-stimulated and ADP- and TRAP-6-stimulated samples. Plasma fibrinogen, von Willebrand factor (vWF), tissue plasminogen activator (tPA), and plasminogen activator inhibitor-1 were determined using standard techniques. Disease severity was stratified on the basis of the ankle-brachial pressure index (ABPI) and the angiographic data were assessed using the Bollinger score.

RESULTS

coagulation and fibrinolysis parameters as well as the P-selectin expression on both stimulated and non-stimulated platelets were significantly increased in patients vs controls (all p<0.01). The respective sensitivity and specificity were as follows: P-selectin expression (81%, 94%), vWF (72%, 86%), fibrinogen (64%, 98%), PAI-1 (44%, 90%), tPA (15%, 100%). P-selectin expression on TRAP-6-stimulated MP correlated with disease severity (r=0.40, p<0.01).

CONCLUSIONS

these findings support the concept of ongoing thrombogenesis in the subclinical progression of PVD and demonstrate the high diagnostic sensitivity of flow cytometric analysis of platelet activation.

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.

[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.

Decreased expression of epidermal growth factor receptor and mRNA of its ligands in Helicobacter pylori-infected gastric mucosa

BACKGROUND

Epidermal growth factor (EGF) and TGF-alpha play a central role in maintaining gastric mucosal integrity. Little is known about the regulative role of the four other widely expressed epidermal growth factor receptor ligands, heparin-binding EGF, amphiregulin, betacellulin and cripto in the gastric mucosa.

METHODS

Nineteen patients with Helicobacter pylori-positive gastritis and 32 healthy controls were investigated. Mucosal mRNA expression of EGF receptor ligands was determined by quantitative PCR before and after H. pylori eradication. PCR products were analyzed by soft laser scanning densitometry. Moreover, the effect of chronic active gastritis on EGF receptor expression was assessed by [125I] EGF receptor autoradiography. Immunohistochemistry was performed for TGF-alpha to localize growth factor expression.

RESULTS

Antral and oxyntic biopsies showed strong mRNA expressions for TGF-alpha, amphiregulin and heparin binding EGF, but not for EGF, cripto and betacellulin. mRNA expression was significantly reduced down to 50% in H. pylori infection, significantly lower compared to normal gastric mucosa, and increased after eradication therapy. Moreover, chronic gastritis was associated with decreased antral EGF receptor binding compared to healthy controls, possibly reflecting reduced autoinduction. Immunohistochemical analyses localized TGF-alpha in the cytoplasma of gastric epithelial cells and revealed its increased expression after H. pylori eradication.

CONCLUSIONS

The data presented suggest that amphiregulin, heparin binding EGF and TGF-alpha are important EGF receptor ligands in the gastric mucosa. H. pylori infection apparently suppresses their mRNA as well as receptor expression that is reversed by H. pylori eradication. This deficiency of the gastroprotective EGF system may contribute to the gastric pathogenicity of H. pylori infection.

P-Selectin expression, platelet aggregates, and platelet-derived microparticle formation are increased in peripheral arterial disease

Platelet volume has been reported to be increased in vascular disease. Therefore, we studied the relationship of mean platelet volume and platelet count as well as flow cytometrically measured platelet size and platelet function in 50 patients with peripheral arterial disease and 50 healthy volunteers. Platelet activation was measured by P-selectin expression analysis on resting and on stimulated platelets, and the determination of platelet aggregates and platelet-derived microparticles using flow cytometry. P-Selectin expression on platelets was significantly elevated in patients suffering from peripheral arterial disease (all P<0.0001). Platelet aggregates (P<0.0001) and platelet-derived microparticles (P<0.0001) were significantly higher in the patient group compared with controls, whereas mean platelet volume and platelet count showed no significant differences. Platelet count was inversely related to mean platelet volume in patients and controls (r = -0.43, P<0.001). The present study supports the hypothesis of platelet hyperreactivity and circulating activated platelets in peripheral arterial disease. Mean platelet volume, and platelet count cannot be used as predictive markers for platelet activation in peripheral arterial disease patients.

Changes in signal transduction in the platelets of patients with peripheral occlusive arterial disease

BACKGROUND

The finding that platelets of patients with peripheral occlusive arterial disease (POAD) circulate in an activated state prompted us to study platelet signal transduction. We hypothesised that platelet hyperreactivity is caused by changes in intracellular signalling.

METHODS

EXPERIMENTAL DESIGN

a single blood sample was taken from the antecubital vein of each participant prior to the start of intravenous treatment with prostaglandins.

SETTING

patients were recruited from our inpatient Department of Cardiology and Angiology at the University Hospital.

PARTICIPANTS

15 hospitalised patients with symptomatic POAD were randomly selected. Patients receiving antiplatelet drugs and those with diabetes were excluded. The control group consisted of 15 healthy volunteers from the medical staff.

INTERVENTIONS

blood tests were performed on the day of admission before any therapeutic intervention.

MEASURES

the platelet activation marker P-selectin was quantified on peripheral blood platelets before and after in vitro stimulation with platelet agonists (adenosine diphosphate, thrombin receptor activator peptide-6). The signal transduction cascade was also selectively blocked by preincubation with either: 1) forskolin, 2) phospholipase C inhibitor U-73122, or 3) bisindolylmaleimide.

RESULTS

A stronger inhibitory effect on ADP-stimulated platelets was seen in patients with U-73122, as indicated by a decrease in mean fluorescence intensity of 51% versus 34% in controls (p<0.0005).

CONCLUSIONS

Our findings support the assumption that changes in platelet signal transduction in POAD lead to platelet hyper-reactivity.

Transvenous biventricular defibrillation

The recent success of biventricular pacing with transvenously implantable left ventricular leads suggests that left ventricular leads may be useful for other modes of therapy. Animal studies showed small leads inserted into a left ventricular vein dramatically reduced defibrillation strength requirements. This article describes a human investigation of the feasibility of biventricular defibrillation. Fifty-one patients undergoing implantable cardioverter defibrillator (ICD) implantation were enrolled. After insertion of a standard ICD lead, a prototype over-the-wire left ventricular defibrillation lead was inserted through the coronary sinus and into a vein on the left ventricle. Lead insertion was guided by retrograde venography. The left ventricular lead's location was randomized to the anterior or posterior vein. Randomized, paired defibrillation threshold (DFT) testing was performed to compare a standard ICD shock configuration (Control: right ventricle- --> superior vena cava+ + CAN+) to 1 of 3 biventricular shock configurations. In the anterior vein, the left ventricular lead was tested with either a single biphasic shock from right ventricle + left ventricle- --> superior vena cava+ + CAN+ or a dual biphasic shock. In the posterior vein, the left ventricular lead was tested with a dual biphasic shock. Dual shocks consisted of a 40% tilt biphasic shock from right ventricle- --> superior vena cava+ + CAN+ followed by another 40% tilt biphasic shock from left ventricle- --> superior vena cava+ + CAN+, delivered from a single 225 microF capacitance. Left ventricular lead positioning was successful in 41 of 46 patients (89%). Mean left ventricular lead insertion time was 17 +/- 17 minutes and 13 +/- 15 minutes for anterior and posterior locations, respectively. Mean DFTs were not statistically lower for the left ventricular shock configurations, but retrospective analysis showed a well-defined region of the posterolateral left ventricle where consistent DFT reduction was achieved with dual shocks (14.0 +/- 2.7 J vs 7.8 +/- 0.9 J; n = 5; p = 0.04). There were no adverse events requiring intervention due to the use of the left ventricular lead. Biventricular defibrillation is feasible and safe under the conditions used in this study. Additional studies are needed to verify whether dual shocks with posterolateral left ventricular lead positions consistently reduce DFTs.

Lipopolysaccharides do not alter metabolic disturbances in hippocampal slices of fetal guinea pigs after oxygen-glucose deprivation

The aim of the present study was to clarify whether endotoxins [lipopolysaccharides (LPS)] have a toxic effect on fetal brain tissue after cerebral ischemia, while excluding their effect on the cardiovascular system. Experiments were therefore performed on hippocampal slices prepared from mature fetal guinea pigs. In particular, we studied the influence of LPS on nitric oxide production, energy metabolism, and protein synthesis after oxygen-glucose deprivation (OGD). Incubating hippocampal slices in LPS (4 mg/L) for as long as 12 h did not alter cGMP tissue concentrations significantly. However, 10 min after OGD of 40-min duration, cGMP tissue concentrations were substantially increased in relation to controls, and this increase was almost completely blocked by the application of 100 microM N:(omega)-nitro-L-arginine, indicating that nitric oxide synthase was activated after OGD in fetal brain tissue. Again, LPS did not have any effect on cGMP tissue concentrations after OGD. Furthermore, addition of LPS altered neither protein synthesis nor energy metabolism measured 12 h after OGD. We therefore conclude that, apart from their well-known influence on the cardiovascular system, LPS do not alter metabolic disturbances in hippocampal slices of fetal guinea pigs 12 h after OGD. A direct toxic effect of LPS on immature brain tissue within this interval does not therefore seem to be very likely. However, delayed activation of LPS-sensitive pathways that may be involved in cell death, or damage limited to a small subgroup of cells such as oligodendrocyte progenitors, cannot be fully excluded.

Implantable dual-chamber cardioverter-defibrillator-pacemaker

The fifth generation of implantable cardioverter-defibrillators offer enhanced modes of detection of atrial and ventricular arrhythmias, antitachycardia pacing and shocks, multiprogrammability, intracardiac electrogram storage, and all functions of antibradycardia dual-chamber pacing including rate responsiveness and mode switching. There is no consensus on the indications for dual-chamber pacemaker defibrillator systems. This review focuses on the four major options of newer devices that might benefit patients: 1) permanent dual-chamber pacing in ischemic coronary disease patients, 2) detection and management of atrial fibrillation or other atrial tachyarrhythmias, 3) some newer indications for pacing, and 4) the suppression of inappropriate interventions. On the basis of published data, newer indications for the dual-chamber systems, advantages and limitations, and future perspectives are discussed.

Radiofrequency ablation of atrioventricular nodal reentrant tachycardia: mechanisms and recurrence rate

Radiofrequency catheter ablation is the treatment of choice in atrioventricular nodal reentrant tachycardia. Electrophysiologic investigations in 623 patients revealed eight mechanisms of tachycardia ablation: Ablation of fast (I) or slow (II), modification of fast (III) or slow AV nodal pathways (IV), modification of both pathways (V), ablation of fast and modification of slow (VI), ablation of slow and modification of fast pathways (VII) and ablation of both pathways (VIII). The criteria of diagnosis of these eight mechanisms of tachycardia ablation are described. Follow-up showed fewer relapses in patients with ablation (0-2%) in comparison to patients with modification of a single AV nodal pathway (8-12%). Alteration of both pathways includes an increasing risk of total AV nodal block, which occurred in 7 patients (1.1%). Detailed analysis of the mechanism of catheter ablation is recommended in all patients after radiofrequency current delivery for AV nodal reentrant tachycardia to estimate the risk of relapse during follow-up or development of total AV block in the particular patient in case of a further ablation procedure.

Principles and practical application of the receiver-operating characteristic analysis for diagnostic tests

We review the principles and practical application of receiver-operating characteristic (ROC) analysis for diagnostic tests. ROC analysis can be used for diagnostic tests with outcomes measured on ordinal, interval or ratio scales. The dependence of the diagnostic sensitivity and specificity on the selected cut-off value must be considered for a full test evaluation and for test comparison. All possible combinations of sensitivity and specificity that can be achieved by changing the test's cut-off value can be summarised using a single parameter; the area under the ROC curve. The ROC technique can also be used to optimise cut-off values with regard to a given prevalence in the target population and cost ratio of false-positive and false-negative results. However, plots of optimisation parameters against the selected cut-off value provide a more-direct method for cut-off selection. Candidates for such optimisation parameters are linear combinations of sensitivity and specificity (with weights selected to reflect the decision-making situation), odds ratio, chance-corrected measures of association (e. g. kappa) and likelihood ratios. We discuss some recent developments in ROC analysis, including meta-analysis of diagnostic tests, correlated ROC curves (paired-sample design) and chance- and prevalence-corrected ROC curves.

Synthesis and characterization of calcium complexes containing eta 2-pyrazolato ligands

Treatment of calcium bromide with 3,5-di-tert-butylpyrazolatopotassium (2 equiv) in tetrahydrofuran afforded Ca(tBu2pz)2(THF)2 (69%). The reaction of this compound with pyridine (3 equiv), tetramethylethylenediamine (TMEDA, 1 equiv), N,N,N',N',N"-pentamethyldiethylenetriamine (PMDETA, 1 equiv), triglyme (1 equiv), and tetraglyme (1 equiv) yielded Ca(tBu2pz)2(py)3 (51%), Ca(tBu2pz)2(TMEDA) (74%), Ca(tBu2pz)2(PMDETA) (50%), Ca(tBu2pz)2(triglyme) (73%), and Ca(tBu2pz)2(tetraglyme) (57%), respectively. Treatment of the tetrahydrofuran adduct of Ca(Me2pz)2, generated in situ, with PMDETA (1 equiv), triglyme (1 equiv), and tetraglyme (1 equiv) afforded Ca(Me2pz)2(PMDETA) (65%), Ca(Me2pz)2(triglyme) (54%), and Ca(Me2pz)2(tetraglyme) (40%), respectively. The X-ray crystal structures of Ca(tBu2pz)2(py)3, Ca(tBu2pz)2(TMEDA), Ca(tBu2pz)2(PMDETA), Ca(tBu2pz)2(triglyme), and Ca(Me2pz)2(PMDETA) revealed six-, seven-, or eight-coordinate calcium centers with eta 2-pyrazolato ligands. Ca(tBu2pz)2(triglyme) sublimes at 160 degrees C (0.1 mmHg). The potential utility of these complexes as source compounds for chemical vapor deposition processes is discussed.

[Alcohol concentration in the coronary sinus after transarterial ablation of septal hypertrophy in hypertrophic obstructive cardiomyopathy]

BACKGROUND AND OBJECTIVE

The size of the resulting myocardial necrosis varies after percutaneous transarterial ablation (PTA) of hypertrophied septum in patients with hypertrophic obstructive cardiomyopathy (HOCM). It was the aim of this study to discover whether the alcohol concentration in coronary sinus (CS) blood is a useful and appropriate parameter and what conclusions can be drawn from it.

PATIENTS AND METHODS

PTA was done in four patients (two women and two men, aged 30-53 years) with HOCM. Before the intervention the gradient across the left ventricular outflow tract ranged form 20 to 80 mmHg, postextrasystolic it ranged from 40 to 180 mmHg. 1 x 2 ml ethanol was injected into the first septal branch in 3 patients, 2 x 2 ml in one. The alcohol concentration in coronary sinus blood was measured every 30 sec for up to 5 min before and after ablation. The amounts were compared with the size of the akinetic area in the echocardiogram and the maximal value of creatine kinase, as a measure of the size of myocardial necrosis.

RESULTS

The left ventricular outflow gradient was reduced in all patients, to 0-30 mmHg and postextrasystolic to 30-90 mmHg. A pacemaker had to be implanted in one patient who developed a 3 degrees AV block. The alcohol concentration in coronary sinus blood ranged from maximally 1.53 and 0.23 per thousand after 30 sec and then fell to 0.56-0.12 per thousand after 5 min. The patient with the highest CS alcohol concentration also had the highest maximal value for creatine kinase (68 mumol/l) and the largest akinetic area in the echocardiogram.

CONCLUSION

The extent of myocardial necrosis can probably be estimated from the CS blood concentration of alcohol after alcohol ablation. If, after the first injection, high alcohol concentrations are measured, further alcohol injections are not indicated.

Bimodal RR interval distribution in chronic atrial fibrillation: impact of dual atrioventricular nodal physiology on long-term rate control after catheter ablation of the posterior atrionodal input

INTRODUCTION

Radiofrequency (RF) catheter modification of the AV node in patients with atrial fibrillation (AF) is limited by an unpredictable decrease of the ventricular rate and a high incidence of permanent AV block. A bimodal RR histogram has been suggested to serve as a predictor for successful outcome but the corresponding AV node properties have never been characterized. We hypothesized that a bimodal histogram indicates dual AV nodal physiology and predicts a better outcome after AV node modification in chronic AF.

METHODS AND RESULTS

Thirty-seven patients were prospectively subdivided into two groups according to the RR histogram of 24-hour ECG monitoring. Before to RF ablation, internal cardioversion and programmed stimulation were performed. Among the 22 patients (group I) with a bimodal RR histogram, dual AV nodal physiology was found in 17 (77%) patients. Ablation significantly decreased ventricular rate with loss of the peak of short RR cycles after ablation (mean and maximal ventricular rates: 32% and 35% rate reduction, respectively; P < 0.01). In 15 patients with a unimodal RR histogram (group II), dual AV nodal physiology was found in 2 (13%), and rate reductions were 16% and 17%, respectively. At 6 months, 3 (14%) patients in group I and 6 (40%) in group II underwent elective AV nodal ablation with pacemaker implantation due to intolerable rapid ventricular response to AF.

CONCLUSION

Bimodal RR interval distribution during chronic AF suggests the presence of dual AV nodal physiology and predicts a better outcome of RF ablation of the posterior atrionodal input.

[Fractional flow reserve as a deciding criterion for intervention in patients with 50% coronary stenoses and impaired myocardial perfusion]

BACKGROUND

A fractional flow reserve (FFRmyo) < 0.75 is a well validated parameter for significance of coronary stenoses in cases of normal myocardial function. We used the FFRmyo limit in patients with impaired myocardial perfusion by myocardial infarction and/or hypertension for intermediate stenoses of the LAD for decision to PTCA and checked the indication by clinical follow-up.

METHODS

In 20 pts (5 women) with chest pain and visual 50 D% LAD stenoses, the FFRmyo was obtained by using a RADI-Pressure-Wire, the CFR by a densitometric technique (HODGSON), and the geometry of stenosis (minimal lumen diameter and diameter stenosis) by quantitative coronary angiography (QCA). EF and the kinetics of the anterolateral wall (expressed as radial shortening fraction) were measured by laevography.

RESULTS

The mean age of our 20 pts. was 59.4 years: 13 of the pts. (65%) had a history of hypertension, 9 (45%) pts. a history of myocardial infarction. The mean diameter stenosis was 50.8%. The mean value of CFR was 2.9. The FFRmyo ranged from 0.66 to 0.90, the mean value was 0.78. The 12 pts. with FFRmyo > or = 0.75 (60%, group A) were treated with the usual anti-anginal medications. A PTCA was performed only in patients with FFRmyo < 0.75 (N = 8 (40%), group B). Except for one pt. with instent restenosis, in the 7 pts. with denovo stenoses stent implantation was performed. Significant differences between the groups A and B were seen only for the total number of myocardial infarctions (8/12 vs. 1/8) and diameter stenosis (48.5% vs. 54.3%). All lesions of group B had a diameter stenosis of 50% or higher. CFR correlated significantly with the radial shortening fraction (r = 0.75), minimal lumen diameter (r = -0.51) and diameter stenosis (r = -0.46). FFRmyo correlated with diameter stenosis (r = -0.47) only. All pts. treated with PTCA were primarily free of pain or reduced angina at least 1 CCS stage; only one developed an angina due to a restenosis (74 D%) 2 months after PTCA and stent implantation. The pts. of group A did not get worse, nor were they readmitted within 6 to 13 months after catheterization.

CONCLUSIONS

Pts. with 50 D% stenoses, impaired myocardial perfusion and FFRmyo < 0.75 had a good long-term benefit concerning clinical and angiographic result. No pts. with FFRmyo < 0.75 had a D% lower than 50; therefore, the PTCA of intermediate stenoses without quantification must be avoided. CFR is not helpful for a decision to PTCA in such cases, because a normal value of CFR is relevant only.

[Cardiac pacemaker therapy for optimizing brain circulation. A possible prevention for cerebrovascular diseases?]

HISTORY AND CLINICAL FINDINGS

A 78-year-old patient experienced dizziness, impairment of mnemic and cognitive function, chronic fatigue and recurrent syncope.

INVESTIGATIONS

Hypertensive heart disease, reduced left ventricular function, and ventricular ectopia classification Lown IVb was documented. Computed tomography showed minimal brain atrophia. Stenoses of the brain supplying arteries and of other intracranial diseases were excluded. A distinct correlation between cardiac output and cerebral blood flow in correspondence to changes of heart rate were found (cardiac output 4.2 l/min during sinus rhythm, 7.4 l/min during temporary atrial pacing--AAI-Mode with a pacing rate of 90/min; 4.8 l/min--AAI-Mode with a pacing rate of 120/min; cerebral blood flow: 70, 74 and 62 ml/100 g per minute, respectively). Thus, impairment of cerebral blood flow autoregulation can be assumed.

TREATMENT AND COURSE

After implantation of a permanent pacemaker the patient was without any complaints. The mnemic and cognitive function improved, dizziness and fatigue disappeared. Synopsis did not occur. 14 months later a sudden onset of complaints occurred caused by atrial fibrillation (heart rate 120/min). Cardiac output and cerebral blood flow were now 4.0 l/min and 35 ml/100 g per minute. After antiarrhythmic drug therapy and restoration of sinus rhythm cardiac output and cerebral blood flow increased and the complaints disappeared again.

CONCLUSION

In patients with impaired capacity of cerebral autoregulation a reduced cardiac function and output can induce a reduction of cerebral blood flow. Thus, impairment of mnemic and cognitive function as well as other unspecific neurological deficits can be caused. In these cases pacemaker therapy has to be discussed as an effective therapeutical concept.