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Biomedical subjects

H Langenfeld

Publications and source records attributed to H Langenfeld.

33 records · Page 2Linked to original sources
PubMed1991

[Primary coronary stent implantation in complex morphology of stenosis or unsatisfactory results of angioplasty].

Early and late results of coronary angioplasty are influenced by the morphology of the coronary artery stenosis. Primary implantation of a balloon-expandable Palmaz-Schatz stent was indicated in 37 patients (31 men and 6 women; mean age 57 +/- 2 years) with symptomatic coronary heart disease and complex morphology of the stenosis. Intracoronary stents were successfully placed in 30 of 37 patients, without complications in all but one. This patient developed a thrombotic occlusion of the vessel 3 days after the procedure which, despite high-dosage thrombolysis treatment, resulted in an anterior wall myocardial infarction. A repeat angiography has since been performed (3-7 months after the procedure) in 25 of the 29 patients with a complication-free course. In 19 of the 25 patients the site of implantation was smooth, while a silent re-occlusion had occurred in one after successful recanalization of a chronic occlusion. Two patients had a subtotal restenosis (12% angiographic restenosis rate). These data indicate that intracoronary stent implantation improves the morphological results after balloon dilatation and reduces the restenosis rate.

Angiography↗
PubMed1990

[Congenital aneurysm of the membranous interventricular septum].

In a 50-year-old patient with complex ventricular arrhythmia (monotopic ventricular extrasystoles in bigeminy and triplet form), coronary angiography with ventriculography revealed an aneurysm of about 2-3 cm diameter that bulged visibly into the right ventricle during the systole. Electrophysiology was able to localise the earliest excitation during the ventricular extrasystoles at the septal border of the aneurysm. Hence, the congenital aneurysm was definitely identified as the source of the arrhythmia. Surgery or drug therapy were not indicated since there was no haemodynamically effective ventricular tachycardia in the patient who was largely free from complaints.

Arrhythmias, Cardiac↗
PubMed1990

Comparative analysis of the action of class I antiarrhythmic drugs (lidocaine, quinidine, and prajmaline) in rabbit atrial and ventricular myocardium.

Effects of three class I antiarrhythmic drugs (quinidine, lidocaine, and prajmaline) on transmembrane resting (RMP) and action potentials (AP) of isolated rabbit atrial and ventricular myocardium were studied at different stimulation rates. The frequency-dependent depression of the maximal upstroke velocity (Vmax) of the AP (sodium channel block) was analyzed according to the "guarded receptor" hypothesis. The resting block (Vmax depression after a resting period) induced by prajmaline (10(-6) M), quinidine (2.2 x 10(-5) M), and lidocaine (4.3 x 10(-5) M) was more expressed in the atrium (44, 28, and 19%, respectively) than in the ventricle (32, 9, and 0%, respectively). There were also significant (p less than 0.05) atrioventricular differences in the frequency-dependent extra block (Vmax reduction on stimulation at 3.3 Hz) for quinidine (39 vs. 26%) and lidocaine (4 vs. 25%). From the analysis, according to the guarded receptor hypothesis, it follows that the three compounds bind preferentially to inactivated sodium channels with about the same affinity to the atrium and ventricle, except for quinidine which shows a significantly smaller dissociation constant in the atrium (5 x 10(-6) M vs. 2.7 x 10(-5) M; p less than 0.001). We conclude that the atrioventricular differences in the resting block are mainly due to atrioventricular differences in the RMP, whereas the differences in the frequency-dependent extra block are based on the shorter atrial AP duration (lidocaine) or are due to higher affinity to atrial sodium channels (quinidine).

Action Potentials↗
PubMed1990

The six-minute walk--an adequate exercise test for pacemaker patients?

In many pacemaker patients bicycle and treadmill ergometry are not practicable. As an alternative, we performed a 6-minute walk on a 20-m corridor in 97 pacemaker patients, who were asked to walk as far as possible determining their speed by themselves. Results were compared with those of bicycle ergometry in 42 of these patients and with treadmill exercise of a group of 92 other pacemaker patients. In the 6-minute walk, performance and maximal heart rate were slightly lower (49 +/- 18 W; 96 +/- 23 beats/min) than in bicycle (57 +/- 16 W; 110 +/- 26 beats/min) and treadmill ergometry (50 +/- 37 W; 102 +/- 35 beats/min). A good correlation was found between walking and bicycling (r = 0.74) and in subgroups of patients with different pacemaker indications. All patients preferred the walk to bicycle ergometry considering it to be more related to daily physical activity. In conclusion, a 6-minute walk is a simple and physiological exercise test for nearly all pacemaker patients with good correlation to other types of exercise. It seems to be preferable to other tests because of its better acceptance and practicability.

Aged↗
PubMed1990

Symptoms, cardiovascular risk profile and spontaneous ECG in paced patients: a five-year follow-up study.

UNLABELLED: Only few data are available about the course of symptoms, cardiac diseases, and spontaneous rhythm in pacemaker patients. Therefore, we followed the course of 308 paced patients (age 72 +/- 11 years) with a mean implantation time of 63 +/- 45 months. RESULTS: The symptom triad of syncope, dizziness, and dyspnea improved remarkably in 93% of patients. Thirty-nine percent suffered from coronary heart disease. The risk factors of hypertension (47%), nicotine (37%), and diabetes mellitus (25%) were found significantly more often than in a normal population with the same age and sex profile. In VVI paced patients with sick sinus syndrome (SSS, n = 67) atrial fibrillation (AF) occurred significantly more often (42%) than in patients with AV block (n = 80, 23%, P less than 0.05). Only one out of 41 DDD paced patients showed AF at follow-up. VVI stimulation seems to favor AF due to retrograde conduction in SSS. Only 3% of patients with SSS developed second- or third-degree AV block. Therefore, atrial pacing is preferable in most patients with SSS.

Aged↗
PubMed1988

Course of symptoms and spontaneous ECG in pacemaker patients: a 5-year follow-up study.

We investigated the course of symptoms and the spontaneous ECG retrospectively in 308 patients who had received a pacemaker because of atrioventricular (AV) block (n = 115), sick sinus syndrome (SSS, n = 107), bradyarrhythmic atrial fibrillation (bradyarrhythmia, n = 51), carotid sinus syndrome (CSS, n = 16), complete bifascicular block associated with 1st degree AV block (n = 13) and with other indications (n = 6). The mean implantation time was 63 months. The clinical state of 93% of all patients improved after pacemaker implantation; their symptoms decreased markedly. Persisting syncopy in some patients with SSS, however, supports a restricted implantation policy. We rarely saw improved AV conduction in patients with AV block (11%). Furthermore, in patients with SSS, atrial fibrillation occurred significantly more often (35%) than in those with AV block (17%; P less than 0.01). Only 3% of patients with SSS developed 2nd and 3rd degree AV block within the observation period. In all patients with initial bifascicular block and additional 1st degree AV block, pacing prevented further syncopal attacks; four of them showed 3rd degree AV block at control, indicating that pacemaker implantation is mandatory in symptomatic patients with bifascicular disease and 1st degree AV block.

Adult↗
PubMed1988

Atrial fibrillation and embolic complications in paced patients.

UNLABELLED: Atrial fibrillation (AF) and thromboembolism are discussed to be complications of the VVI mode. We reinvestigated the spontaneous ECG and the anamnesis of 246 pacemaker patients with the indications second and third degree atrioventricular block (AV block, n = lll), sick sinus syndrome (SSS, n = 101) and other indications (n = 34), all had shown sinus rhythm at implantation. The mean implantation time was 63 +/- 45 months (203 VVI and 43 dual chamber pacemakers). THE RESULTS: (1) Atrial fibrillation was found in 63 patients (26%). Only one of them had a DDD pacemaker inserted, the implantation time of dual chamber devices being shorter, however, (2) The incidence of AF in patients with SSS (37%) was significantly higher (P less than 0.01) than in patients with AV block (19%). (3) Three patients suffered from strokes or transitory ischemic attacks in the follow-up, only one of them had AF at control. CONCLUSIONS: Our results confirm that VVI stimulation favors AF long-term which is most likely due to irritation of the atrial rhythm by retrograde conduction. In our patients the incidence of thromboembolic complications was not higher in the group of patients with AF. However, from this study in surviving patients, we cannot exclude that we lost some patients due to severe stroke.

Aged↗
PubMed1988

[Not Available].

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History, Modern 1601-↗
PubMed1986

Rate adaptive pacing--clinical experience with three different pacing systems.

Physiological stimulation can be achieved by either bifocal or rate responsive pacing. The latter pacemakers adapt the heart rate to physical activity by biological signals. Out of many possible approaches only three pacemaker systems for rate responsive pacing are available: the QT-pacemaker (Tx or Quintech), the respiratory biorate pacemaker, and the activity detecting Activitrax. Our own experiences (8 QT, 6 Biorate, 8 Activitrax pacemakers) and a survey of 95 QT- and 37 Biorate pacemakers from 11 centers are reported. The Biorate pacemaker functions without any problems; its present disadvantage is limited programmability. With the Tx pacemaker failing, frequency adaptation (26%) was found more often in the early series, mostly due to voltage polarization at the tip of the electrode. The Activitrax pacemaker gives satisfactory frequency adaptation, largely depending on the activity of the muscles of the shoulder and pectoral region.

Aged↗
PubMed1986

[Clinical experiences with 3 different rate-adaptive pacemaker systems].

Physiological stimulation can be achieved by either bifocal or rate responsive pacing. The latter pacemakers adapt the heart rate to physical activity by biological signals. Of many possible approaches only three pacemaker systems for rate responsive pacing are available: the QT pacemaker (Tx or Quintech), the respiratory Biorate pacemaker and the activity detecting Activitrax. First our own experiences (8 QT, 6 Biorate, 8 Activitrax pacemakers) and a survey of 95 QT- and 37 Biorate pacemakers from 11 centers are reported. The Biorate pacemaker functions without any problems, its present disadvantage is limited programmability. With the Tx pacemaker failing frequency adaptation (26%) was found more often in the early series, mostly due to voltage polarisation at the tip of the electrode. The Activitrax pacemaker gives satisfactory frequency adaptation, largely depending on the activity of the muscles of the shoulder and pectoral region.

Adult↗
PubMed1984

Electrophysiological profile of the antiarrhythmic compound asocainol studied on perfused guinea-pig hearts and on isolated cardiac preparations.

The studies deal with electrophysiological effects of asocainol [(+/-)-6,7,8,9-tetrahydro-2,12-dimethoxy-7-methyl-6-phenetyl-5 H-dibenz(d,f)azonine-1-ol] on isolated perfused guinea-pig hearts (Langendorff-preparation), on right ventricular papillary muscles, on Purkinje fibres from the guinea pig, and on isolated sinus nodes from the rabbit. In the perfused heart (n = 5) the lowest effective concentration of asocainol is about 0.2 mumol/l. At a concentration of 2 mumol/l the cardiac electrogram shows in spontaneously beating hearts a mean decrease in frequency of 15%, in electrically driven hearts (150/min at 32 degrees C) prolongation of PQ (+31%), of QRS (+24%) and of QT (+5%). In papillary muscles (32 degrees C; K+e 5.9 mmol/l; stimulation rate 0.5 Hz) asocainol (3-30 mumol/l) exerts the following effects: no change of the resting potential, concentration-dependent reduction of the maximum rate of rise (Vmax) of the action potential (AP) (-16 to -67%) as well as of the AP-amplitude (-4 to -16%), and shortening of the AP-duration at 50% repolarisation (-18 to -43%). The steady-state dependence of Vmax on the resting potential (RP) determined by variation of K+e (5.9-15 mmol/l) is shifted by asocainol to more negative potentials. The percentage deviation from controls of the Vmax-RP relationship is more pronounced at lower membrane potentials. The influence of asocainol on the recovery from inactivation of Vmax shows marked time-dependence. Slow response (Ca2+-mediated) APs elicited by strong stimuli in a K+e-rich solution (K+e 20-24 mmol/l) respond to asocainol (3-10 mumol/l) with a marked reduction in amplitude, Vmax and duration.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMedDate not supplied

Electrophysiological interactions between carbachol and class I antiarrhythmic drugs (lidocaine, quinidine)--experimental studies in rabbit atrial myocardium.

UNLABELLED: Cholinergic agents exert no direct effect on the fast Na+ inward current but may influence the binding characteristic of class I antiarrhythmic drugs in atrial myocardium by shortening the action potential (AP) duration or by increasing the resting potential (RP). In order to examine such possible interactions we performed experiments using conventional intracellular microelectrodes on isolated preparations of rabbit atrial myocardium (Ke 2.7 mM, temperature 32 degrees C). At first the influence of the cholinergic agent carbachol (1 mg/l = 6.7 x 10(-6) M) on the RP and AP was examined at different stimulation rates (1.0, 2.5, and 3.3 Hz). Thereafter measurements were repeated under the influence of lidocaine (10 mg/l = 2.2 x 10(-5) M) or quinidine (5 mg/l = 2.2 x 10(-5) M) alone and in combination with carbachol (1 mg/l). RESULTS: (statistically significant differences, p less than 0.05): Carbachol increased the RP by about 10 mV and shortened the AP by about 60%. The maximal upstroke velocity of the AP (Vmax) was not significantly altered at 1.0 and 2.5 Hz, but increased under carbachol at 3.3 Hz. After addition of carbachol to the lidocaine-containing solution, Vmax increased to its control level at all stimulation rates. In experiments with quinidine, Vmax also increased after addition of carbachol but remained significantly below the control values. CONCLUSIONS: Carbachol effects on Vmax are most likely attributable to earlier recovery (caused by the shortening of the AP) and to faster recovery kinetics (due to hyperpolarization). The attenuation of the class I effect of lidocaine by carbachol can thus be considered mainly a consequence of the shortening of the inactivated state which results in a reduced affinity of lidocaine to its receptor and allows earlier dissociation of the drug. Minor binding of the drug due to hyperpolarization may play the major role in interactions between carbachol and quinidine.

Action Potentials↗
PubMedDate not supplied

Influence of beta-adrenergic stimulation on the fast sodium current in the intact rat papillary muscle.

The loose-patch-clamp technique was used on intact cardiac papillary muscle of the rat to examine whether the fast sodium inward current (INa+) is influenced by the beta-adrenergic stimulant isoproterenol (ISO) or by 8-bromo-3',5'-cyclic adenosine monophosphate (8-Br-cAMP), respectively. The amplitude of INa+ evoked by test pulses of 5 ms to a transmembrane potential of 0 mV and its time to peak were analyzed. The availability of INa+ was tested with conditioning pulses of 2.5 s to potentials between -130 mV and -50 mV. The potential of half-maximal availability was slightly shifted to more negative values by 1 microM ISO (2.0 mV, n.s.), as well as by 50 microM 8-Br-cAMP (4.0 mV; p less than 0.05). The peak amplitude of INa+ elicited from strongly negative potentials was increased by ISO (18%, n.s.), while 8-Br-cAMP exerted no directional effect. Depolarizing conditioning pulses (-60 mV) decreased INa+ to 13.3% of the maximal attainable current under control conditions, while ISO decreased INa+ to 9.1% of control (p less than 0.1). Corresponding values under the influence of 8-Br-cAMP were 11.4% and 8.3% (p less than 0.05). Moreover, in the presence of ISO there was a significant shortening of the time to peak of INa+ (0.56 ms to 0.50 ms at -80 mV conditioning potential, p less than 0.05) which could not be detected in the presence of 8-Br-cAMP.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Bromo Cyclic Adenosine Monophosphate↗