Electrophysiology and pharmacology of cardiac arrhythmias. IX. Cardiac electrophysiologic effects of beta adrenergic receptor stimulation and blockade. Part A.
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Action Potentials↗
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Electrophysiology and pharmacology of cardiac arrhythmias. IX. Cardiac electrophysiologic effects of beta adrenergic receptro stimulation and blockade. Part C.
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Action Potentials↗
[Protocols of electrophysiological study. Italian Group for Study of the Electrophysiology of Arrhythmias].
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Electrophysiology and pharmacology of cardiac arrhythmias. IX. Cardiac electrophysiologic effects of beta adrenergic receptor stimulation and blockade. Part B.
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Administration, Oral↗
Effects of brain-stem and thalamic lesions on the corneal reflex: an electrophysiological and anatomical study.
In 9 patients with Wallenberg's lateral medullary syndrome, one patient with a midbrain lesion involving the right side of the tegmentum, and 2 patients with a thalamic lesion, corneal reflexes were investigated by a new electromyographic technique. The electrophysical results were compared with the results obtained by clinical observation. In the lateral medullary lesions the electrophysiologically obtained reflex responses showed four types of abnormality. Type A consisted of a bilateral delay and type B a bilateral absence of the corneal reflex response to stimulation on the affected side in combination with a normal reflex response on both sides when the cornea on the normal side was stimulated. Type C, which was present in one case, and type D which was seen in 3 cases, consisted of a bilateral absence of the corneal reflex upon stimulation on the affected side; stimulation on the unaffected side produced a normal reflex response on the intact side in combination with, respectively, a delay or absence of the corneal reflex response on the affected side. Comparison of the clinical observations with the electrophysiological findings revealed minor discrepancies in type A and B abnormalities. However, the electrophysiological type C and D abnormalities were not detected by clinical observation. These findings demonstrate that electrophysiological recording of the corneal reflex may reveal clinically undetectable abnormalities. From the electrophysiological findings it is concluded that the corneal reflex is conducted along medullary pathways running both ipsilaterally and contralaterally from the stimulated side before connecting, respectively, with the ipsilateral and contralateral facial nucleus. From the anatomical findings it is suggested that the ascending pathways from the spinal fifth nerve complex to the facial nuclei are located in the lateral reticular formation of the lower brain-stem. The normal corneal reflex responses in the presence of thalamic and midbrain lesions involving nociceptive fibres in the trigeminothalamic tract do not support a previously postulated long-loop reflex arc passing through this tract. The suprabulbar influence upon the corneal reflex is discussed.
Brain Diseases↗
[Electrophysiologic evidence of three different types of the 'slow fibers' of extraocular muscles (author's transl)].
The author reports on electrophysiologic investigations of extraocular muscles in rabbits in vivo by means of standardized glass microelectrodes. The results of investigation on muscle-fiber membrane resting potentials of 'slow fibers' as well as on postsynaptical potentials of 'slow fibers' are analyzed after having elucidated the problems as well as the methods employed and the experimental setup. By figures and synopses in tabular form the author illustrates the electrophysiologic parameters of three different types of muscle fibers of 'slow fibers' of extraocular muscles that can with certainty be differentiated electrophysiologically. In the discussion references are made to the importance of the submitted results of investigation for basic research and for clinical ophthalmo-electromyography. Finally, the trends of investigation of the electrophysiologic analysis of extraocular muscles are discussed.
Action Potentials↗
The natural history of conduction system disease in myotonic muscular dystrophy as determined by serial electrophysiologic studies.
To evaluate the progression of conduction system disease in myotonic muscular dystrophy, nine patients underwent serial electrophysiologic studies at a mean of 35 months apart. At the initial study, seven patients had first-degree atrioventricular block and three of these seven had disease in the His-Purkinje system (HV greater than 55 msec). At the second study, seven patients had prolonged HV intervals, and during the almost 3-year period, HV intervals increased by at least 5 msec in all seven patients. No electrophysiologic or electrocardiographic measures could be found that correlated with progression of conduction disease in these patients. Because of the failure of electrophysiologic measures to predict progression of conduction disease in these patients, electrophysiologic studies are recommended only for symptomatic patients. If significant disease is found in either impulse formation or conduction, permanent pacemaker therapy is warranted.
Adult↗
The cardiac electrophysiological effects of nifedipine.
A study was carried out on the electrophysiological effects of a sublingually administered antianginal drug: nifedipine (20 mg). The results show a significant shortening of sinus cycle length from 925 +/- 249 msec to 810 +/- 245 msec, (p less than 0.005) and the disappearance of some interpolation and echo zones. There are no significant effects on the other evaluated parameters of sino-atrial and AV-node function. In one case, during atrial pacing, a second-degree, Wenckebach type, A-V block was present only before nifedipine. The following conclusions were reached: 1. nifedipine has no significant electrophysiological effect on the human heart; 2. the electrophysiological effects observed are probably indirect and related to the vasodilating effect of the drug; 3. the absence of direct cardiac electrophysiological actions may be useful in patients suffering from coronary artery disease and presenting disturbances in the formation and/or conduction of the cardiac impulse.
Adult↗
Clinical and electrophysiological studies of diphtheritic neuritis in Jordan.
Eleven patients with acute diphtheritic neuritis were studied clinically and electrophysiologically. Decreased conduction velocity and increased distal motor latency were present in most patients within two weeks of the onset of neurological symptoms. Velocities later fell to approximately 45% of mean normal values. Wasting with electrophysiological evidence of denervation was present in 3 patients. Nerve conduction studies had returned to normal within 3 months in 8 patients. There was a striking dissociation between the time course of the clinical and the neurophysiological abnormalities: early in the illness, peripheral nerve conduction was normal in some patients despite the presence of severe weakness, and later, the maximum electrophysiological abnormalities were sometimes found after clinical recovery had commenced. The nature and sequence of the clinical and electrophysiological changes are in accord with the known pattern and distribution of the pathological changes in the disease.
Adolescent↗
Electrophysiological effects of edrophonium in the innervated and the transplanted denervated human heart.
In order to determine the mechanism of action of edrophonium on the cardiac conduction system, we used His bundle recording and pacing techniques to examine the electrophysiological effect of edrophonium in 6 patients undergoing diagnostic evaluation for coronary artery disease and in 9 cardiac transplant recipients who were free of acute graft rejection. After control measures were made of sinus cycle length, conduction intervals, and conduction system refractory periods, edrophonium was administered by constant intravenous infusion, and all electrophysiological measurements were repeated. In the normally innervated patients, edrophonium significantly increased sinus cycle length from 778 +/- 21 ms to 883 +/- 36 ms (P less than 0.01), AH interval from 88 +/- 11 ms to 100 +/- 12 ms (P less than 0.01), and AV nodal functional refractory period from 351 +/- 44 ms to 391 +/- 36 ms (P less than 0.05). In the patients with transplanted hearts, edrophonium had no electrophysiological effect other than increasing the cycle length of the remnant recipient atrium from 722 +/- 21 ms to 798 +/- 31 ms (P less than 0.01). We conclude that the electrophysiological effects of edrophonium in man are mediated primarily through autonomic innervation of the heart.
Autonomic Nervous System↗
[The carpal tunnel syndrome--clinical symptomatology and electrophysiological findings (author's transl)].
In the first part of this study 17 patients with a clinically clear-cut carpal tunnel syndrome but with normal electrophysiological findings have been controlled after 1 to 3 years. In 12 of these patients an other cause of the complaints could be found. In 2 patients no definite diagnosis could be made and in 3 the previous diagnosis was considered to be corrected. Control electromyography was pathological in 2 of them and 1 patient was symptom-free after the operation. In the second part 133 hands with clinical symptoms of a carpal tunnel syndrome were examined clinically and electrophysiologically. In the group of patients with pathological electrophysiological findings there were significantly more objective signs than in those with normal EMG findings. In 13 of these patients which could be followed an other diagnosis could be made. It was not possible to establish a clinical index for the carpal tunnel syndorme. For a definite diagnosis, positive clinical and electrophysiological findings are required.
Adult↗
Intraoperative electrophysiologic mapping during cardiac surgery.
Intraoperative mapping is a method to document the surgical anatomy of cardiac tissues with electrophysiologic importance cartographically at time of surgery. The presented communication gives a survey of the present status of the technique of electrophysiologic mapping and its essential clinical applications. Special attention in this regard is directed to the intraoperative identification of the specialized AV conduction system in congenital cardiac malformations with unpredictable location of His bundle, to the detection of accessory AV bundles in patients with the Wolff-Parkinson-White syndrome and to the intraoperative morphological study of ventricular reentry tachycardias. Suitable technical equipment for "clinical" intraoperative electrophysiologic mapping is described in detail.
Cardiac Surgical Procedures↗
Electrophysiologic and pathologic correlations in two cases of chronic second degree atrioventricular block with left bundle branch block.
This study concerns two cases of chronic 2 degrees atrioventricular (A-V) block with left bundle branch block (LBBB). Pathological studies included serial section of the conduction systems. Case 1 had type I 2 degrees block with LBBB. Electrophysiological studies revealed type I 2 degrees block proximal to the His bundle recording site and a prolonged H-V interval (60 msec). Pathologically there was a moderate to marked fibrosis of the approaches to the A-V node and of the A-V node, marked fibrosis of the left bundle branch, and moderate involvement of the right bundle branch. The changes proximal to the His bundle were more marked than the changes distal to this bundle. Case 2 had type II and 2:1 2 degrees A-V block with LBBB. Electrophysiologically the site of block was distal to the His bundle recording site, and there was a prolonged A-V node and severe involvement of both bundle branches. The changes distal to the His bundle were more severe than the changes proximal to the His bundle. This study reveals that the electrophysiologic data more closely approximated the pathologic findings than did surface electrocardiographic data alone. It also emphasizes that there may be multiple sites of disease in chronic 2 degrees block with bundle branch block.
Aged↗
Pragmatic Phenotype-Electrophysiology-Genomics Integration in Pediatric Congenital Myasthenic Syndromes: Insights From 36 Patients in a Single-Center Study in China.
AIMS: To characterize the clinical, electrophysiological, and genetic spectrum of pediatric CMS and evaluate genotype-informed outcomes using an integrated phenotype-electrophysiology-genomics approach. METHODS: We retrospectively reviewed 36 pediatric CMS patients evaluated at a single center between 2015 and 2025. Clinical features, RNS, targeted NGS/WES variants, ventilator use, treatments, ACMG/AMP classifications, and MG-ADL outcomes were analyzed. RESULTS: Of 36 patients, 28 (77.8%) developed symptoms in the neonatal period or infancy. Biallelic variants involved 17 CMS genes; postsynaptic CMS was most common (55.6%, 20/36). COLQ and CHRNE were the most frequent genes (13.9%, 5/36 each), followed by CHAT (11.1%, 4/36). VUS were detected in 19 patients (52.8%, 19/36), including 8 with biallelic VUS supported by phenotype, neuromuscular transmission findings, treatment response, and follow-up. RNS showed a ≥ 10% decrement in 16/21 tested patients (76.2%). CHAT-CMS was associated with higher ventilator use (3/4 vs. 6/32; p = 0.041) and early mortality (3/4 vs. 1/32; p = 0.002). Median MG-ADL improved from 5 to 3 after genotype-informed therapy. CONCLUSION: Pediatric CMS shows marked genetic heterogeneity and frequent VUS-related uncertainty. Integrating phenotype, electrophysiology, and genomics supports diagnosis and mechanism-guided therapy. CHAT-CMS is high risk for early respiratory failure and mortality.
Humans↗
Pathologic correlations in three cases of bilateral bundle branch disease with unusual electrophysiologic manifestations in two cases.
Examination of the conduction system in three patients with bifascicular block who had electrophysiologic studies forms the basis for this report. Patients 1 and 2 had left bundle branch block and Patient 3 right bundle branch block and left axis deviation. The H-V interval was prolonged in each case (70, 65 and 60 msec, respectively). Serial section examination of the conduction system revealed sclerodegenerative involvement of both bundle branches in all cases. In Case 1, atrial extrastimulus testing converted left to right bundle branch block; in Case 2, it delineated a sinus echo zone with repetitive sinus nodal reentrance. In the latter case serial section revealed extensive amyloid infiltration of the approaches to the sinoatrial (S-A) node and the atrial preferential pathways. In Case 3, with right bundle branch block and left axis deviation, serial section revealed greater involvement of the anterior part of the main left bundle branch than of the posterior portion as well as involvement of the second part of the right bundle branch. The study revealed excellent correlation between electrophysiologic and pathologic findings in three cases of intraventricular conduction disease and demonstrated an anatomic basis for the electrophysiologic findings resembling alternating bilateral bundle branch block. Sinus nodal reentrance may be related to disease in the approaches to the S-A node thereby causing delay in perinodal tissue allowing sinus reentrance. Finally in Case 3, the anatomic substrate for left axis deviation may lie in a greater involvement of the anterior portion than of the posterior portion of the main left bundle rather than in the corresponding portions of the periphery.
Aged↗
Respective importance of different electrophysiological parameters in alcoholic neuropathy.
An electrophysiological study of alcoholic and normal subjects is presented. The aim was to evaluate the respective importance of the various parameters. The subjects were divided into 4 groups: (I) normal subjects; (II) chronic alcoholics without clinical evidence of neuropathy; (III) chronic alcoholics with sensory symptoms; (IV) chronic alcoholics with both motor and sensory symptoms. The electrophysiological parameters tested were: conduction velocity (CV) in Ia sensory fibres, motor fibres, and cutaneous sensory fibres of the popliteal nerve, CV in the sural nerve, amplitude of the cutaneous sensory action potentials (SAP) in the sural and popliteal nerves, H reflex and M response of the soleus muscle, and electromyograms from the extensor digitorum brevis muscle. In the 3 groups of alcoholics, the electrophysiological findings were more abnormal than the clinical symptoms could have predicted. The more sensitive parameters were: (1) CV in the Ia sensory fibres of the popliteal nerve, which is slowed very early (in Group II) and (2) measurement of the amplitude of sural and popliteal SAP's which are also reduced early (in Group II). The nature of the mechanisms involved are discussed.
Action Potentials↗
Dissociation between the electrophysiological properties and total tissue cyclic guanosine monophosphate content of guinea pig atria.
The purpose of this study was to investigate the role of cyclic guanosine monophosphate (cyclic GMP) in mediating the direct electrophysiological effects of acetylcholine in guinea pig atria. Acetylcholine significantly diminished spontaneous rate of right atria without increasing cyclic GMP content. Reductions in rate following acetylcholine were augmented by pretreatment with physostigmine, but cyclic GMP levels remained unchanged. In left atria, acetylcholine significantly shortened action potential duration within 5 seconds (both with and without physostigmine pretreatment), but cyclic GMP content was not significantly elevated. Cyclic GMP levels in right atria were significantly increased in response to acetylcholine when the Ca2+ content of the buffer was elevated from 1.25 mM TO 2.5 MM; however, reductions in automaticity in the right atria were not augmented in the high Ca2+ buffer. Marked increases in cyclic GMP content were produced by Na nitroprusside superfusion without changing automaticity of right atria or action potential duration of left atria. Finally, both right and left atria were superfused with cyclic GMP analogs (8-bromo cyclic GMP and dibutyryl cyclic GMP) at high concentrations (10(-4)) for 15 minutes without producing significant effects on spontaneous rate or action potential duration. These results failed to show a correlation between total tissue cyclic GMP content and the electrophysiological effects of acetylcholine on guinea pig atria. The reasons for this are either that cyclic GMP does not mediate directly the electrophysiological effects of acetylcholine, or that small changes in cyclic GMP concentrations, undetectable when total tissue nucleotide levels are measured, occur in discrete effector pools of the cardiac cell to mediate the intracellular effects of the choline ester.
Acetylcholine↗
Electrophysiological studies in patients with the Wolf-Parkinson-White syndrome.
Electrophysiologic studies in patients with the Wolff-Parkinson-White (WPW) syndrome are performed for diagnostic and therapeutic reasons. Surface electrocardiographic leads plus intracardiac electrograms from different locations are stimultaneously recorded. Programmed electrical stimulation of the heart permits confirmation of pre-excitation in questionable cases and assessment of the mechanism of the arrhythmias which these patients develop as well as their therapeutic approach. The most frequent form of paroxysmal regular tachycardia observed in WPW is based on an AV-junctional re-entry mechanism utilizing the accessory pathway in the retrograde direction. The second clinically relevant arrhythmia encountered in these patients is atrial fibrillation with very rapid ventricular rates due to almost exclusive A-V conduction by way of the accessory pathway. Ventricular fibrillation may occasionally ensue as a result of these fast ventricular rates during atrial fibrillation. Determination of the antegrade effective refractory period of the accessory pathway may identify the group of patients prone to the development of this complication. The intravenous injection of Ajmaline can by a non-invasive aid in the selection of patients for further electrophysiological evaluation when this drug fails to induce complete antegrade block over the accessory pathway during sinus rhythm. Patients with tachyarrhythmias which are difficult to control with conventional drug therapy should undergo an electrophysiological investigation to select either more effective antiarrhythmic treatment or, in medically refractory patients, appropriate pacing or surgical techniques.
Anti-Arrhythmia Agents↗