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Results 751 - 800 of 1026
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Burggren W - - 1986
Dose-response curves for the action of acetylcholine (ACh) and its antagonist, atropine, upon heart rate in situ were made for three larval stages and adults of the bullfrog, Rana catesbeiana. The absolute magnitude of heart rate inhibition at any ACh concentration progressively increased throughout larval development. Unexpectedly, metamorphosis to the ...
Manz M - - 1986
Antitachycardia pacing for ventricular tachycardia (VT) is associated with the possibility of fibrillating the heart; on the other hand, the frequency of VT and patient discomfort can limit treatment with the automatic implantable cardioverter/defibrillator (AICD). To contribute to the further development of a universal pacemaker, we evaluated the combined use ...
Fröhlig G - - 1986
Three patients are reported whose DDD pacemakers reverted to the asynchronous mode in the absence of skeletal muscle or electromagnetic (EMI) interference. In all three cases, the basic cardiac rhythm was atrial fibrillation with fast ventricular response due to intrinsic AV conduction. Noise reversion was triggered by the patients' own ...
Wang F S - - 1986
Prolonged electrocardiographic (Holter) recording was performed to analyze terminal electrical events in 23 hospitalized adults who died without apparent cardiac disease. Most patients showed a gradual slowing of heart rate with shifting of cardiac pacemaker downward from the sinus node or atria to the atrioventricular junction and ventricles, resulting in ...
Oreto G - - 1986
Modulation of ventricular parasystole by sinus beats has been shown both in vitro and in vivo to result in a classic biphasic phase-response curve. The first clinical presentation of 3 cases of supernormal modulation of ventricular parasystole resulting in a triphasic phase response curve is reported. Supernormal modulation reflects an ...
Higgins J R - - 1986
An automatic burst pacemaker (Cybertach-60) was used to treat drug-resistant recurrent ventricular tachycardia in a patient with mitral valve prolapse. The arrhythmia was associated with multiple syncopal episodes and aborted sudden death. During a 23 month follow-up period the patient has remained asymptomatic and more than 2,000 episodes of ventricular ...
van Mechelen R - - 1986
ECG tracings of three patients in whom AV universal (DDD) pacemakers were implanted intermittently demonstrated dropped P waves. In one patient, true atrial undersensing was present; in the others, sensing of the atrial electrode was appropriate, but sensing of sinus P waves was intermittently blocked by normal pacemaker operation. In ...
Robbens E J - - 1986
A patient who suffered from sinus node dysfunction and automatic atrial tachycardias underwent pacemaker implantation during which time a unilateral left superior vena cava was found. Despite the known difficulties in using this venous route, it was possible to place a transvenous endocardial screw-in lead in a stable position in ...
Cripps T - - 1986
The uptake of cardiac catheterisation and operation and of permanent pacemaker implantation in a district hospital in Surrey from 1979 to 1984 was studied prospectively. The 1982-84 figures for coronary artery operation indicated that 362 procedures/million population/annum were needed in the district. If patients with greater than or equal to ...
Greenspon A J - - 1986
A 48-year-old man with previous aortic valve surgery and aortic root repair had a DDD pacemaker inserted (using transvenous leads) for the treatment of complete heart block. An atrial J active fixation electrode was used. Four weeks following implantation the patient returned with an unusual electrocardiographic rhythm demonstrating two separate ...
Masini G - - 1986
The aim of this study was to investigate whether premature atrial stimulation is able to induce a shifting of the sinus node pacemaker. For this purpose we compared, in 18 patients, the curve of sinus node function obtained with Strauss' method with that resulting from the scanning, with premature atrial ...
Szekeres L - - 1986
In the present experiments the dominant role in the genesis of arrhythmias of stimulation of beta adrenoceptors over that of alpha adrenoceptors has been demonstrated by: (i) infusion of catecholamines in the isolated right ventricular Purkinje fiber preparation of rabbits; and (ii) by subepicardial microinfusion of these substances to anesthetized ...
Reisen W K - - 1986
Exposure to simulated "mid-winter" conditions (16 degrees C, 10L:14D) inhibited the expression of autogeny among the female progeny of field-collected Culex tarsalis females. The same F1 progeny expressed 43% autogeny when reared in an insectary under simulated "summer" conditions (25 degrees C, 16L:8D). Diapausing F1 progeny did not express autogeny ...
Sukhum P - - 1986
Methods and devices for permanent cardiac pacing remained relatively stable for over two decades with use of the single-chamber ventricular demand (VVI) pacemaker. However, changes have occurred in the 1980s and are expected to continue with the availability of more advanced technology and with increasing knowledge about cardiac pacing. The ...
Lamas G A - - 1986
Both electrocautery and internal defibrillation are routinely used in cardiac operations. The cases of 5 patients are presented in whom backup-mode reversion or injury of permanently implanted pulse generators occurred during a cardiac procedure. The theoretical explanations for backup-mode reversion and generator or tissue injury are discussed, and recommendations are ...
Pimenta J - - 1986
A 44-year-old female had Chagas' disease with right bundle branch block, right axis deviation, and ventricular ectopic beats. An invasive evaluation showed a prolonged HV interval of 100 ms. A Medtronic Versatrax 7000 was implanted, after which a pacemaker-mediated tachycardia was observed. The esophageal lead ruled out the possibility of ...
Kovács K L - - 1986
The effects of surfactants, lipids and amphiphilic viologen mediators on H2 production from dithionite as well as on Ru(bpy) sensitized H2 photoproduction by hydrogenase from Thiocapsa roseopersicina was studied. Three systems which differed as to the nature of the hydrophobic matrix around the hydrogenase were tested. An enhanced hydrogenase activity ...
Fromell G J - - 1986
The Wenckebach phenomenon, or type I AV block, refers to a progressive lengthening of impulse conduction time, followed by a nonconducted impulse, or dropped beat. It can occur in a variety of pathologic settings, especially inferior myocardial infarction. Although a temporary pacemaker may be required, full spontaneous recovery is the ...
McCabe J B - - 1986
A 68-year-old man with sick sinus syndrome was treated by implantation of a DDD pacemaker. He subsequently developed a rapid heart rate and was found to have a pacemaker-mediated tachycardia due to tracking of atrial fibrillation by the pacemaker. The tachycardia was abolished by reprogramming the pacemaker, and the patient ...
Beaver B B - - 1986
A unique mechanism of "cross-talk" has recently been described in the Gemini 415A DDD pacemaker in which cross-inhibition of the ventricular output stimulus may occur in the early Gemini 415A models which were manufactured with dual anodal rings interconnected by a wire. The Gemini 415A units with dual anodal rings ...
Barold S S - - 1985
Signals responsible for pacemaker oversensing may arise from the pacing system itself, P or T wave, concealed ventricular extrasystoles, skeletal muscle potentials, and distant electromagnetic fields. Oversensing is the most common cause of pacemaker pauses and a common clinical problem during follow-up of patients with implanted pulse generators. This article ...
Ausubel K - - 1985
The pacemaker syndrome is an iatrogenic disorder that can result from hemodynamic sequelae of ventricular pacing. Symptoms range from fatigability to syncope and occur during the time the ventricles are being stimulated by the pulse generator. Postulated mechanisms include loss of atrioventricular synchrony, vasodepressor reflexes, and retrograde atrial activation. Prevention ...
Gilchrist J M - - 1985
We studied a young man with presumably idiopathic seizures that were refractory to phenytoin therapy. Sick sinus syndrome was found after an episode of unconsciousness, but seizures continued despite the insertion of a demand ventricular pacemaker. Evaluation revealed a left temporal seizure focus, and combined EEG and ECG monitoring during ...
Rubens A B - - 1985
We studied performance on tests of visual neglect and left lateral gaze after caloric stimulation in 18 patients with left-sided visual neglect after strokes. Except for one patient with absent vestibulo-ocular responses, all improved during caloric stimulation on the left by cold (LC) or on the right by warm water ...
Janosik D - - 1985
Torsades de pointes, a distinctive type of polymorphous ventricular tachycardia, may be induced by critically timed ventricular stimulation during electrophysiologic studies or, rarely, in patients with temporary or permanent ventricular pacemakers. The following case illustrates how, when temporary ventricular pacing is instituted to maintain heart rate in a patient with ...
Surawicz B - - 1985
Ventricular fibrillation is the most common mechanism of sudden unexpected cardiac death in persons with asymptomatic or symptomatic coronary artery disease. The electrophysiologic mechanisms reviewed in this article include: automaticity of pacemaker fibers, transformation of nonpacemaker into pacemaker fibers, "injury" currents and reentry. Some of the conditions facilitating ventricular fibrillation ...
Lamas G A - - 1985
Pacemaker-mediated tachycardias (PMT) have received much recent attention. We describe the course and treatment of a 60-year-old man with an AV universal (DDD) pacemaker who developed a pacemaker-mediated tachycardia. The tachycardia was initiated by the coincidence of an unsensed P-wave, a QRS that was also not sensed due to the ...
Jeans S P - - 1985
Measurements of radiation distributions in the vicinity of the couch were undertaken for a number of projections commonly employed during cardiac radiological studies. Three types of investigations were considered; cardiac catheterisations, pacemaker implants and percutaneous transluminal coronary angioplasties. The radiation dose to staff involved in these procedures was estimated. For ...
Brandt J - - 1985
The interpretation of the ECG of a dual chamber pacemaker necessitates the identification of atrial activity. This is a prerequisite for the evaluation of pacemaker function and for the correct adjustment of programmable pulse generators. The assessment of atrial capture in standard 12-lead ECGs is, however, sometimes rather difficult. Esophageal ...
Dangman K H - - 1985
We studied the effects of single premature stimuli on automatic and triggered rhythms occurring in preparations of isolated canine Purkinje fibers. Preparations were made from false tendons, the subendocardial right bundle branch, and infarct zone Purkinje fibers 24 hr after occlusion of the left anterior descending coronary artery, and were ...
Olson C M - - 1985
Cardiac pacing has been used successfully in patients with asystole or bradycardia compromising hemodynamics when it was applied soon after the onset of the event. An external cardiac pacemaker was used as part of initial resuscitative efforts for patients in primary, out-of-hospital, cardiac arrest who arrived in the emergency department ...
Frumin H - - 1985
In a patient with a dual chamber pacemaker that senses in both the atrium and ventricle (VDD, DDD), a ventricular depolarization temporally displaced from a P wave can cause retrograde atrial activation and initiate an endless loop pacemaker-mediated tachycardia. A case in which an endless loop tachycardia was initiated by ...
Luceri R M - - 1985
Cardiac pacemakers are now at the forefront of medical technology. The ability to provide pacing therapy adapted to the individual patient has resulted in significant patient benefit. Although the indications for cardiac pacing have changed little over the past decade, the types of pacemakers available for specific bradyarrhythmias have proliferated ...
Shade S K - - 1985
Transcutaneous electrical nerve stimulation units used in conjunction with cardiac pacemakers have traditionally been an absolute contraindication for these patients. In this case report, a patient successfully used a TENS unit in conjunction with a temporary cardiac pacemaker. No interference was noted by the ECG readout. This finding indicates that ...
Erdman S - - 1985
Pacemaker carriers are at risk when undergoing operations involving the use of diathermy. The Shaw Scalpel utilizes a method by which the cutting edge of the blade is heated to a selected temperature that seals blood vessels as they are cut. No electrical currents are passed to or through the ...
van Gelder L M - - 1985
Retrograde atrial activation during ventricular pacing has often been a cause of intermittent or persistent arrhythmias (pacemaker-mediated tachycardia) in AV universal pacemakers. We recently encountered two cases in which VA conduction was responsible for atrial malpacing in patients with an implanted AV universal pacemaker, one programmed in DDD and one ...
Medina R - - 1985
Great advances in pacemaker technology have produced devices capable of a vast array of physiologic adaptations formerly unimaginable, opening new possibilities in the pacemaker treatment of almost all rhythm disturbances. Nearly all units in use today are of the inhibited type, except for some antitachycardia applications. The AV-sequential mode (DVI) ...
Javelet J - - 1985
Bilateral vertical incisions were made in the maxillary and mandibular labial mucosa of eight young green vervet monkeys. Incisions were closed with either interrupted 4-0 black silk sutures or by the application of isobutyl cyanoacrylate. Mucosal specimens containing the incisions were examined histologically and scored for degree of inflammation at ...
Higgins J R - - 1985
Many investigators have reported the use of various permanent pacemaking modes in the long-term management of patients with recurrent ventricular tachycardia. The three general types of antitachycardic pacemakers are: (1) underdrive; (2) burst; and (3) scanning pacemakers. Such devices have been activated externally or have had automatic activation. Each antitachycardic ...
Grigorov S S - - 1985
Rhythm disturbances induced by endocardial pacing were studied in 15 patients. Atrial extrasystoles were found in 8, ventricular extrasystoles in 5, ventricular tachycardia in 1 and ventricular fibrillation in 1 patient. In all cases, an implanted pacemaker EKS-222 was used working in VVI regime. The connection of the above-mentioned rhythm ...
Nordlander R - - 1985
To evaluate the complication rate during AV universal pacing (DDD), 41 consecutive patients with complete heart block were studied and followed up for 2-30 (mean 10.8) months. The Cordis Sequicor Theta was used in 6 patients and the Siemens-Elema 674 in 35. Clinical problems related to the pacemaker treatment occurred ...
Müller C - - 1985
The author discusses whether post-partum psychoses are to be considered as a clinical entity per se. The studies conducted in Lausanne seem to demonstrate that the authors of DSM III were correct in excluding this possibility - of all the patients with a post partum episode, 65% had one or ...
Kamei K - - 1984
The effects of nitroglycerin (NTG) on cardiac function can be evaluated by echocardiography. In this paper, we discuss the effects of NTG on cardiac function in two groups of subjects, one with artificial pacemakers implanted with a fixed heart rate, and the other examined as the control group. Left ventricular ...
Przybojewski J Z - - 1984
A 48-year-old man with symptoms of presyncope and congestive cardiac failure had hypertrophic cardiomyopathy (HCM) without obstruction. Complete heart block (CHB), a rare complication of this disease, was preceded by complete left bundle-branch block. Right ventricular (RV) heart failure was a dominant clinical feature but improved dramatically after temporary transvenous ...
Nakamura R - - 1984
In reaction time (RT) experiments, shifts of arousal level induced by postural changes were examined in 10 normal subjects and 10 patients with SMON. Vocal RTs were recorded at neutral position (N) and facilitating position of the left arm (FA) or the left leg (FL). RT-ratios between two positions, FA/N ...
Seltzer J P - - 1984
Multiparameter programmable DDD pacemakers are said to have an uncountable number of possible parameter combinations. It is probable that a number of these combinations, particularly when triggered by one or more critically timed native events, will result in bizarre and unanticipated rhythms sustained entirely within the timing circuit of the ...
Harthorne J W - - 1984
The advent of dual chamber pacing systems that restore atrioventricular synchrony and allow rate variability in response to physiologic stress has provided a major advance in pacing therapy. Undesirable pacemaker-mediated tachycardias may arise when the atrial sensing amplifier of a VDD or DDD device detects a retrogradely conducted P-wave, ectopic ...
van Gelder L M - - 1984
A 67-year-old male, suffering from ventricular tachycardia unresponsive to drug therapy, received a universal AV sequential pacemaker (DDD,M). The pacemaker was programmed in the DVI mode, pacing rate 100 bpm, AV interval 250 ms. After implantation, the patient experiences two episodes of tachycardia that proved to be pacemaker tachycardia with ...
Repolski M - - 1984
Sinus node dysfunction may produce in some cases life threatening medical emergencies. From 138 patients with sinus node dysfunction followed up in our department, we present 8 cases in which emergency situations required special therapeutical approaches (precordial thump, atrial or ventricular pacing, permanent pacemaker implantation). These situations appeared spontaneously, during ...
Edhag O - - 1984
Eleven patients with bifascicular block complicating anteroseptal acute myocardial infarction were studied to determine the effect of prophylactic permanent pacing; eight of them also had transient high grade atrioventricular block during the acute phase of the infarction. One month after the infarction an electrophysiological study was performed and a bradycardia ...
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