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H Volkmann

Publications and source records attributed to H Volkmann.

At least 19 recordsLinked to original sources
PubMed1992

Right ventricular conductance to establish closed-loop pacing.

Innovations in pacing technology, which include the addition of rate-responsive features to programmable pacemakers, can improve the quality of life of patients suffering from sick sinus syndrome. Among the strategies providing rate-adaptive cardiac pacing, the most attractive is the physiological restoration of closed-loop chronotropic control. This paper describes how autonomic nervous system (ANS) control information is extracted from dynamic measures of myocardial contractile performance obtained from unipolar conductance measurements using the stimulation electrode in the right ventricular cavity. The pacemaker uses the ANS information to modulate pacing rate and restore normal physiological control of heart rate. A new algorithm, regional effective slope quantity (RQ), for isolating the ANS signal was developed. The resulting signal, ventricular inotropic parameter (VIP), is a normalized parameter proportional to the strength of the ANS inotropic signals to the myocardium. The efficacy of the ANS control concept was evaluated in multi-centre studies. Patients with AV block and VIP-controlled pulse generators performed defined exercise protocols. The ANS-controlled pacing rate and the spontaneous sinus rate were closely correlated. Blood pressure and subjective patient reports further indicated that good control of the cardiovascular circulation was achieved.

Autonomic Nervous System↗
PubMed1992

Autonomic nervous system controlled closed loop cardiac pacing.

A multicenter clinical study is presented, which focuses on the reestablishment of closed loop cardiac control in patients with chronotropic insufficiency. Using the information about sympathetic tone contained in the myocardial contractility, it is possible to reconnect the heart rate to the physiological control mechanisms. Intracardiac impedance is measured with the ventricular electrode and the ventricular inotropic parameter (VIP) is derived from that. The VIP serves directly as input to the control of heart rate by the pacemaker. Over 200 patients have received autonomic nervous system (ANS) controlled pacemakers. The patient-pacemaker system was investigated in different ways. This included standard exercise tests, long-term studies of every day activities over 24 hours, psychological, and pharmacological challenges. To prove the validity of the approach we specifically looked at (1) the appropriateness of changes in paced heart rate with sympathetic tone during exercise, (2) the correlation between heart rate and sinus rate, if detectable, and (3) the correlation between the echocardiographically determined preejection period (PEP) and the VIP controlled heart rate.

Autonomic Nervous System↗
PubMed1992

Balloon electrode catheter for transesophageal atrial pacing and transesophageal ECG recording.

A new balloon electrode catheter (10 French) with five or six balloon electrodes placed on the cardiac side was developed for transesophageal atrial pacing and bipolar ECG recording. The diameter of the hemispheric electrodes is 6 mm and the length of the esophageal balloon is 10 cm. The transesophageal atrial pacing threshold was measured with the balloon electrode catheter by transesophageal programmed atrial stimulation (TPS) (n = 54). At the onset of TPS, the feeling, capture (n = 54), and pain voltage threshold (n = 6) were measured by increasing the amplitude of the pacing voltage during high rate bipolar atrial pacing and bipolar atrial ECG recording. In 38 TPS, the capture threshold was lower than the feeling threshold (n = 28). In 16 TPS, the capture threshold was higher than the feeling threshold. In conclusion, painless atrial pacing and excellent ECG recording can be achieved with a multipolar esophageal balloon electrode catheter with a low pacing voltage amplitude and a high P wave amplitude.

Cardiac Pacing, Artificial↗
PubMed1992

Termination of tachycardias by transesophageal electrical pacing.

To evaluate the therapeutic significance of noninvasive transesophageal pacing for termination of tachycardias the method of rapid atrial or ventricular transesophageal pacing was used in 233 patients with different tachycardiac arrhythmias. We were able to terminate atrial flutter in 136 of 162 patients by transesophageal rapid atrial stimulation (conversion to sinus rhythm in 75 cases, induction of atrial fibrillation in 61 cases). Atrial tachycardias were interrupted in 17 of 23 patients (sinus rhythm in 11 cases, atrial fibrillation in six cases). AV reciprocating/AV nodal supraventricular reentry tachycardias were terminated in 62 of 63 patients (sinus rhythm in 58 cases, atrial fibrillation in four cases). By transesophageal rapid ventricular pacing ventricular tachycardias could be terminated in ten of 15 patients. The success rate of transesophageal pacing was influenced by the pacing rate, by the type of tachycardiac arrhythmia inclusive by the type of atrial flutter and by the tachycardia's cycle length. Because the success rates are comparable with invasive technique and the procedure is simpler, the noninvasive transesophageal antitachycardiac pacing should be respected as the method of the first choice in patients with supraventricular tachycardias.

Atrial Flutter↗
PubMed1992

[Measuring intracardiac impedance for the determination of sympathetic nerve activity in frequency-adapted electrostimulation--Part 2: Clinical results].

The results of a multicenter clinical study involving patients receiving the first ANS controlled rate adaptive pacemaker are presented. In the patients with primary or secondary chronotropic insufficiency, it is possible to reestablish the closed loop control system that includes the baroreceptors, the medulla oblongata, the cardiac output and the mean arterial blood pressure. This system serves to keep the blood pressure constant in the face of changing demands on the circulation. Utilizing intracardiac impedance measurements, the myocardial contractility can be determined, which contains information about the current sympathetic tone, and thus represents an excellent physiological input for a rate adaptive mechanism. The results presented are taken from a study population of over 200 patients. The objective evaluation of this new approach was performed echocardiographically, by ergometry and 24-hour Holter monitoring.

Adult↗
PubMed1992

Investigations into a new antiarrhythmic substance Z-2-amino-5-chlor-benzophenon-amidin-hydralazin in humans.

Z-2-amino-5-chlor-benzophenon-amidin-hydralazin is a new chemical potential antiarrhythmic substance. The blood levels were investigated after different dosages and forms of administration in patients and volunteers. The determination of the substance can be performed by high-pressure liquid chromatography. In addition the pharmacokinetic parameters were calculated. The pharmacokinetic profile is similar in humans and animals.

Administration, Oral↗
PubMed1991

[Electrophysiological anti-arrhythmia effects of tiracizine in ventricular tachycardia].

The electrophysiologic effects and antiarrhythmic efficacy of tiracizine, a new class I antiarrhythmic drug, were studied in 16 patients with documented sustained ventricular tachycardia (VT) after intravenous drug application and in 6 patients after oral drug administration by means of programmed ventricular stimulation (PVS). After intravenous tiracizine (0.3 mg/kg) the VT was no longer inducible by PVS in 3 of 16 patients and became nonsustained in another patient. In 11 of 13 patients with further inducible VT the cycle duration of VT increased after tiracizine (mean 29 ms). After oral tiracizine (150-225 mg/day) the VT induction was suppressed in one patient. In a second patient the VT became nonsustained. Cycle length of VT in 4 patients with persistent induction of VT was longer after therapy (mean 88 ms). Antiarrhythmic efficacy of intravenous or oral tiracizine can be expected in at least one third of patients with VT.

Administration, Oral↗
PubMed1991

[Therapeutic value of trans-esophageal electrostimulation in tachycardic arrhythmias].

We were able to terminate atrial flutter in 136 of 162 patients by transesophageal rapid atrial stimulation (conversion to sinus rhythm in 75 cases, induction of atrial fibrillation in 61 cases). Atrial tachycardias were interrupted in 17 of 23 patients (sinus rhythm in 11, atrial fibrillation in 6 cases), AV reciprocating resp. AV nodal supraventricular tachycardias were terminated in 32 of 33 patients (sinus rhythm in 28 cases, atrial fibrillation in 4 cases). By transesophageal rapid ventricular and/or atrial pacing, ventricular tachycardias could be terminated in 10 of 15 patients. The success rate of transesophageal pacing is influenced by the type of tachyarrhythmia, by the type of atrial flutter and by the stimulation rate. It is not influenced by the tachycardia's cycle length. Because the success rates are comparable with invasive technique and the procedure is simpler, the non-invasive transesophageal antitachycardia pacing represents a useful method for termination of tachycardic arrhythmias.

Adult↗
PubMed1990

Electrophysiological evaluation of tachycardias using transesophageal pacing and recording.

Programmed electrical stimulation of the heart to initiate and terminate tachycardia has been useful in the evaluation of supraventricular and ventricular tachyarrhythmias. A wide use of these procedures, however, failed because of the expense of the invasive approach as well as the lack of physician experience in smaller hospitals. These disadvantages of the invasive proceeding can be abolished by transesophageal pacing. In our study, supraventricular tachycardias were initiated by programmed transesophageal atrial stimulation in 251 patients (AV node reentry in 75 patients, orthodromic AV reciprocating tachycardia using accessory pathway in 97 patients, antidromic AV reciprocating tachycardia in 11 patients, and atrial reentry in 39 patients). The stimulation protocol included one and two extrastimuli during sinus rhythm and after a pacing drive at different cycle lengths. The electrophysiological mechanism of tachycardias was determined by surface ECG, VA interval (esophageal lead), initiation mode at programmed transesophageal stimulation and by behavior of AV conduction and refractoriness. In 29 patients the mechanism of tachycardia was not clear. Invasive electrophysiological study was done in 219 of these 251 patients. In only nine patients, the supposed mechanism of tachycardia was not confirmed by invasive investigation. In 11 patients, the electrophysiological mechanism remained uncertain. In conclusion, the noninvasive transesophageal pacing is an appropriate method for evaluation of supraventricular tachycardia. It allows serial drug testing in a simple manner for finding an effective antiarrhythmic treatment.

Adult↗
PubMed1990

Diagnostic value of carotid sinus hypersensitivity.

In order to evaluate the diagnostic value of carotid sinus hypersensitivity (CSH) we have investigated 163 asymptomatic patients (88 male, 75 female, mean age 57.9 +/- 22.7 years) and 210 symptomatic patients (108 males, 102 females, mean age 61.1 +/- 28.1 years) with syncopes or dizziness. Thirty two of the 163 asymptomatic patients (20%) and 87 of the 210 symptomatic patients (41%) showed CSH (asystole greater than or equal to 3 sec during carotid sinus pressure). Male patients had a higher number of CSH than female (28% vs 10% in the asymptomatic group, 48% vs 34% in the symptomatic group). Electrophysiological investigations were performed in all 210 symptomatic patients. Normal electrophysiological results had 94 of the 210 patients. Thirty seven of these 94 patients showed CSH (39%). Prolonged sinus node recovery time (SNRT) and/or prolonged sinoatrial conduction time (SACT) were evaluated in 38 patients. Seventeen of the 38 patients had CSH (45%). Disorders of atrioventricular (AV) conduction were evaluated in 43 patients. Seventeen of the 43 patients showed CSH (40%). Thirty-five patients had both AV conduction disorders and prolonged SNRT or SACT. Sixteen of these 35 patients showed CSH (46%). In conclusion, no significant difference was found between patients with and without pathological electrophysiological results. The CSH is without value for predicting sinus node dysfunction and AV conduction disorder.

Age Factors↗
PubMed1990

[Terminating ventricular tachycardias by mechanical heart stimulation with precordial thumps].

To determine value and limitations of mechanical cardiac stimulation by precordial thumps for termination of ventricular arrhythmias, we systematically treated 47 consecutive cases of ventricular tachycardias (resp. ventricular flutter or fibrillation) by this method. In 20 of 37 cases of ventricular tachycardias the arrhythmia was terminated by manual stimulation. The mean tachycardia rate amounted to 145/min (range from 102 to 222/min) in successfully treated patients. Bursts of rapid precordial thumps were more effective than single precordial thumps. In 17 of the 37 cases of ventricular tachycardia. The mean tachycardia rate was significantly higher (176/min, range from 120 to 250/min) than in successfully treated cases. Altogether, ventricular tachycardias with heart rate less than or equal to 160/min were terminated by mechanical stimulation in 17 of 22 cases, and ventricular tachycardias with heart rate greater than 160/min only in 3 of 15 cases. Ventricular fibrillation (n = 3) or ventricular flutter (n = 7) was not interrupted in any case by precordial thumps. In patients with ventricular tachycardia, mechanical stimulation extends the therapeutic possibilities. The rate of success is higher, the lower the tachycardia rate. The tachycardia rate is the only predictive parameter for therapeutic success.

Adult↗
PubMed1989

[The anti-arrhythmia effect and hemodynamic effects of Bonnecor in intravenous administration].

For testing the efficiency of Bonnecor in intravenous administration (0.3 mg/kg) 36 patients were examined electrophysiologically (31 with paroxysmal supraventricular tachycardias, 5 with ventricular tachycardias). In other 6 patients haemodynamic investigations were performed by means of right-heart catheterization and thermodilution. The supraventricular tachycardias induced by programmed electrostimulation could be interrupted by administration of Bonnecor in 45% of the cases. After the administration of Bonnecor the inducibility of supraventricular tachycardias was suppressed in 11 of the 31 patients. In 2 of the 5 patients with ventricular tachycardia an evocation of ventricular tachycardias was no more possible after an intravenous application of Bonnecor; a medicamentous termination of the ventricular tachycardias had been tried only in one case. Clinically relevant negatively inotropic effects could not be proved. Apart from insignificant malaises in few cases, no side-effects occurred.

Adult↗
PubMed1989

[Ventricular late potentials in patients with cardiomyopathies in relation to electrophysiologic and myocardial biopsy findings].

With the noninvasive registration of late ventricular potentials there is the possibility to obtain statements about a regionally delayed excitation of ventricular parts which may refer to an increased inclination to ventricular tachyarrhythmias. Late ventricular potentials in patients with suspicion of primary diseases of the myocardium more frequently appeared both in the case of inducible non-sustained or sustained ventricular tachycardias and in the presence of simultaneous fibrous hypertrophy of the myocardium and interstitial fibrosis in the bioptate of the myocardium than in noninducibility of ventricular tachycardias and in the absence of histological changes of the myocardium. Thus in patients with cardiomyopathies a certain predicting significance seems to be ascribed to the evidence of late potentials in the highly increased signal-averaged ECG both for the ability to evoke ventricular tachycardias by programmed ventricular stimulation and for the presence of more distinct histological changes of the myocardium.

Adult↗
PubMed1989

[Complications of temporary transvenous endocardial pacemaker therapy].

The prospective analysis of the results of the temporary transvenous-endocardial pacemaker therapy in 591 cases of treatment resulted in a total rate of complications of 37.1%. Hereby the main part of complications were disturbances of the function of electrodes (28.3%). The greatest numbers of complications showed infiltrable electrode catheters which were applied at bedside with a dislocation rate of 17.2% and a rate of not achieved stable stimulation positions of 13.7%. The smallest numbers of complications were to be observed in semiflexible stimulation catheters, which were positioned under X-ray control (dislocations in 4.1%, no achievement of a stable stimulation position in 3.3%). For the practice of the temporary pacemaker therapy from this analysis result particularly consequences in the choice of a suitable stimulation catheter and the methodical approach in positioning of this catheter.

Adams-Stokes Syndrome↗
PubMed1989

Bundle branch reentrant tachycardia treated by transvenous catheter ablation of the right bundle branch.

Recurrent episodes of ventricular tachycardia not responding to medical treatment occurred in a 56-year-old man. Electrophysiological investigation showed ventricular tachycardia due to bundle branch reentry. Using a method similar to catheter ablation of the atrioventricular junction, ablation of the right bundle branch was performed by an electrical shock of 250 joules. While before the ablation ventricular tachycardia occurred several times a day and its induction by programmed ventricular stimulation was facilitated by the administration of antiarrhythmic drugs, no initiation of ventricular tachycardia was possible after ablation of the right bundle branch. Over a follow-up of 30 months the patient has not suffered from tachycardia and the right bundle branch block persists.

Bundle of His↗