ajmaline and Sinoatrial-Block

Sinus node function and other electrophysiologic properties of the heart in patients with atrioventricular or intraventricular blocks are not well documented. I therefore performed electrophysiological studies in 35 patients with chronic high degree atrioventricular block (AVB--group I), 20 patients with bifascicular block (BFB--group II) and in 24 control subjects (group III). Multilevel conduction disturbances were found in 51.5% of patients with AVB and in only 10% of patients with BFB. Sinus node dysfunction was disclosed in 3 patients (8.6%) with AVB (in 1 it was functional) and in 3 patients (15%) with BFB. A new modified method for recording sinus node electrogram (SNE) was described. By applying this method, SNE was recorded successfully in 80% of cases. The results are comparable to those of other methods. Retrograde conduction was observed in 34% of patients with AVB, 75% of patients with BFB and in 38% of control subjects. It plays an important role in the pathogenesis of the "pacemaker syndrome" in patients with VVI pacemakers. Atrial hyperexcitability was observed in 5.7% of patients in gr. I, 10% in gr. II and 4.2% in control group only. Rare occurrence of atrial arrhythmias provoked by electrical stimulation provides the possibility to use DDD or VDD pacing systems in patients with AVB or BFB. Inadequate rate of response to exercise (chronotropic incompetence) was observed in most patients with sinus node dysfunction, but it occurred also in patients with normal sinus function.. 1) Sinus node dysfunction is uncommon in patients with atrioventricular or intraventricular blocks. 2) Persistence of abnormal sinus node function and atrioventricular or intraventricular conduction disturbances after autonomic inhibition is an argument for organic disseminated injury of the conduction system (binodal disease). 3) Electrophysiological evaluation of sinus node function, retrograde conduction, artial hyperexcitability and chronotropic response to exercise permit suitable choice of physiological pacing mode (VDD, DDD, DDR, VVIR) in patients with AVB or BFB.

Topics: Adolescent; Adult; Aged; Ajmaline; Atrioventricular Node; Electric Stimulation; Electrocardiography; Exercise Test; Heart Block; Humans; Middle Aged; Sinoatrial Block; Sinoatrial Node; Ventricular Function, Left; Ventricular Function, Right

Nine cases of major ventricular arrhythmia (tachycardia (VT), fibrillation (VF), torsades de pointe) are reported in patients with sequellae of myocardial infarction but without residual angina or cardiac failure. --Six of these disturbances of excitability occurred after a bradycardia due to sino atrial block (SAB) which favoured the breakthrough of abnormal automatic foci. This form of the bradycardia-tachycardia syndrome was demonstrated by endocavitary electrophysiological exploration.. These were the only cases of major ventricular arrhythmia observed in a series of 88 SABs. Reputedly benign, they illustrate the potential gravity of a conduction defect in patients with sequellae of myocardial infarction. --Three other cases of abnormal ventricular excitability complicating the administration of 1 mg/kg of Ajmaline to test for paroxysmal block after myocardial infarction. These were the only cases of VT observed in a series of 800 Ajmaline tests. The three patients have had no further episodes of VT after 1 year's follow-up. On the other hand, in 43 Ajmaline tests without VT in patients with myocardial infarction, 6 cases of VT and 1 lethal VF were later observed. This demonstrates the lack of significance of episodes of VT during Ajmaline tests, the depressant action of the drug on intracardiac conduction favouring the initiation of reentry. In conclusion, a history of myocardial infarction exposes the patient to the risk of major ventricular arrhythmias in SAB, the detection of which should indicate pacemaker therapy from the first symptoms. The use of an intravenous antiarrhythmic agent should be avoided as it may aggravate arrhythmias. However, the arrhythmia is of no prognostic significance.

Topics: Aged; Ajmaline; Arrhythmias, Cardiac; Electrocardiography; Female; Heart Block; Humans; Male; Myocardial Infarction; Prognosis; Sinoatrial Block

18 patients with sinus bradycardia (8 SB) and tachycardia-bradycardia syndrome (10 TBS) were investigated using various vagan reflex manoeuvres, atrial pacing (AP), pharmacological tests and His bundle (HB) recordings, to assess autonomic influences, sinus node function and atrioventricular (AV) conduction. Three types of responses (R) were defined as normal (N), supernormal (SN), poor autonomic (PA). Poor reflex responses to vagal manoeuvres, performed in 12 patients, have no statistical significance. MxCSRT at AP suppression was measured in 13 patients: it was normal (less than or equal to 500 msec) in 8 and increased (from 680 to 4,200 msec) in 5 patients with appearance of junctional escapes. Moreover, AP suppression revealed a sinoatrial block (SAB) in 1 patient with normal MxCSRT. Isoprenaline, administered intravenously (3-6 mug) in 9 patients, showed 4 NR, 3 PAR und 2 SNR (unusual sinus tachycardia, 1; atrial fibrillation, 1). Atropine (0.5-1 mg), used in 15 patients, revealed 5 PAR and 1 SNR. Prostigmine (0.5 mg), used in 11 patients, induced 6 NR and 5 PAR. Lanatosid C (0.08 mg), administered in 16 patients, showed 10 NR, 5 PAR and 1 SNR. Finally, ajmaline (100 mg), given in 13 patients, revealed 5 junctional rhythms and one 2:1 SAB. HB recorded in 17 patients showed an increase of AH interval (greater than 140 msec) in 5 patients and a slight increase (60 msec) of HV interval in 2 patients. Three patients developed 2nd-degree AV block at paced rates greater than or equal to 110/min. Abnormal responses at AP suppression and reduced drug responses were noted in 5 patients suffering from Adam-Stokes attacks; a permanent pacemaker was inserted in 4 of these 5 patients. In conclusion, provocative tests, in 18 patients with SB or TBS, suggest a diffuse process disease involving the autonomic function of both sinus node and AV junction (11 patients) and the AV system (6 patients). These immediate results must be correlated with histological findings in the conduction system, as shown in one of our cases previously reported.

Topics: Adult; Aged; Ajmaline; Arrhythmia, Sinus; Atropine; Blood Pressure; Bradycardia; Bundle of His; Digitalis Glycosides; Female; Heart Arrest; Heart Conduction System; Heart Rate; Humans; Isoproterenol; Male; Middle Aged; Neostigmine; Pacemaker, Artificial; Sinoatrial Block