[An evaluation of radiofrequency current catheter ablation in the treatment of paroxysmal tachycardia].
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Biomedical subjects
Publications and source records attributed to F S Gu.
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50 cases of acute myocardial infarction (AMI) were examined for ventricular late potential (VLP) six times in total within 4 weeks. At the same time the patients clinical condition was observed. It is found that: (1) In our group the occurrence of VLP in AMI was 28% and VLP was unstable in both acute stage and recovery stage. (2) During acute stage, the difference of positive VLP rate is significant between the ventricular fibrillation group and normal rhythm group (P less than 0.05), but there is no significant difference between the ventricular ectopia group and normal rhythm group. During recovery stage, the difference of positive VLP rate is very significant between the ventricular ectopia and normal rhythm group (P = 0.001). As there was only 1 case of ventricular fibrillation occurring in the recovery stage, no comparison could be made. (3) There is no correlation between VLP and clinical conditions, such as age sex, location of the infarction, existence of old infarction and LVEF. However, the difference of the peak serum CPK level is significant between VLP positive and negative group (P less than 0.05).
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19 cases of pacemaker syndrome were observed in 121 patients implanted with VVI pacemakers. The main manifestations of pacemaker syndrome were dizziness, lightheadedness, fatigue, hypotension and congestive cardiac failure after permanent ventricular pacing. The incidence of pacemaker syndrome was 20% in patients with sick sinus syndrome and 13.2% with A-V block. Pacemaker ECG showed retrograde ventriculoatrial conduction in 25 of 121 cases. Among these patients, 14 (56%) had pacemaker syndrome, while only 5 of 96 cases without ventriculoatrial conduction had this syndrome, so the incidence of the two groups were quite different, P less than 0.0001. The frequency of ventriculoatrial conduction in patients with sick sinus syndrome was higher than in patients with A-V block (16/45 vs 9/76, P less than 0.05). The electrophysiologic study were performed in 17 cases before PM implantation. 3 cases had 170-190 ms ventriculoatrial 1:1 conduction. Retrograde ventriculoatrial conduction in pacemaker ECG were present during ventricular pacing in all of them.
In recent few years, many authors had discussed the possibilities of using bipolar precordial leads to replace lead V5 in diagnosing anterior wall myocardial ischemia. But there still remains some problems to be solved: (1) Are there any difference between bipolar precordial leads and lead V5 in wave forms? (2) What kind of factors influence the ST deviation? 36 patients were studied by comparing unipolar lead V5 with respect to three different bipolar chest leads CM5, CC5, CL5 both in lying and sitting positions. We found that: (1) The differences is least significant between bipolar CC5 and lead V5 while it is most significant between bipolar lead CM5 and lead V5. (2) The deviation of ST segment in bipolar leads is affected both by potential at negative electrode as well as potential at positive electrode. Statistical analysis revealed that ST segment is positively related to the potential on positive electrode and negatively related to the potential on negative electrode. For this reason, therefore, in the view point of most comparable ST deviation with lead V5 for monitoring of myocardial ischemia, it is advisable to locate the negative electrode at the site on chest with least potential. Usually we place the negative electrode on V6R to compose a bipolar lead CC5.
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