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Biomedical subjects

F Huerta

Publications and source records attributed to F Huerta.

28 records · Page 2Linked to original sources
PubMed1976

[Electrophysiologic effects of amiodarone in Wolf-Parkinson-White syndrome].

Eight patients with WPW syndrome were catheterised and, during the course of this investigation, the electrophysiological effects of amiodarone were assessed. By registering the potentials of the bundle of His and by using the stimulus-test technique, we were able to measure the refractory periods of the atrium and of the normal and accessory conducting pathways both before and during the first 40 minutes after an intra-atrial injection of 5 mg/kg of amiodarone chlorhydrate. The action of the conduction time was also studied. In the five cases in which we were able to measure it, the effective refractory period of the abnormal pathway increased, which led in two instances to the temporary suppression of all pre-excitation. At the same time, it was repeatedly found that the refractory periods of the A-V node were increased: the effective refractory period in 3/3 cases, and the functional refractory period in 2/2 cases. The effective refractory period of the right atrium was increased in 5 cases, and did not change in the others. The intranodal conduction time (A-H- interval) was always increased after amiodarone. Finally, in three patients runs of reciprocal tachycardia could be initiated by premature atrial stimulation. In one case, this was no longer possible after amiodarone. In the other two cases, although the attacks could still be brought on, they were slower because of the lengthening of the A-H interval. These findings explain why amiodarone is effective in controlling the tachycardia of WPW syndrome.

Action Potentials↗
PubMed1975

[Electrophysiological study of 2 cases of ventricular pre-excitation compatible with the presence of Mahaim's fibers].

Report of two cases of ventricular pre-excitation in which the presence of Mahaim's fibres was suggested by the electro-physiological studies. In both cases, the short-circuit of the His bundle was responsible for the abnormally short HV interval. In a patient, atrial acceleration induced an increase of rh at first, related to an A-V delay without HV variation. For a cycle of 360 ms, HV lengthened suddenly from 15 to 40 ms while QRS changed configuration, which is in favour of a functional exclusion of an accessory pathway. Combination with the pre-excitation of a left bundle-branch block complicated, in this case, the problems of identification. The other case responded also to cardiac pacing by an increase of the A-V delay due mainly to intra-nodal conduction slowing. In the same time HV increases from 20 to 30 ms (for a cycle change from 480 to 315 ms) and the delta wave decreased progressively. For a higher rate there was a 2:1 A-V block proximal to H. The extrastimulus method produced initially the same results. On the contrary, when the coupling-interval decreased to 290 ms, HV increased suddenly from 25 to 45 ms, with disappearance of the pre-excitation pattern. At a still shorter interval, HV shortened again (25 ms) in parallel with a marked lengthening of the A-V nodal conduction times, thus revealing a "gap" phenomenon of the accessory pathway.

Adolescent↗
PubMed1975

[Ventricular tachycardia due to premature supra-ventricular beats with a normal QRS complex. Analysis of a case].

Report of attacks of ventricular tachycardia in a 39 year-old man, free from heart disease. Cardiac pacing showed that the tachycardia could be induced by premature supraventricular beats normally propagated to the ventricles, and by atrial acceleration. The same part played by the cardiac rate on triggering of attacks was demonstrated during ventricular pacing. Besides, the possibility to interrupt the tachycardia by one electrically induced ventricular beat, supports the hypothesis of a re-entry machanism. The QRS configuration during the arrythmia suggested a propagation of excitation starting from the posterior-inferior area of the left ventricle. However, the absence of anomalies of the supraventricular beats initiating the tachycardia excluded a circus movement resulting from a unidirectional block on the left anterior hemibranch. More probably there existed an area of micro-reentry, stimulating the left ventricle from the posterior branches of the His-Purkinje system.

Adult↗
PubMedDate not supplied

The chronotropic effect of adenosine and ATP in dogs. The antagonism by theophylline.

We analyzed the action of adenosine and adenosine triphosphate (ATP) on the chronotropism of the dog heart in situ. The compounds were administered either intravenously (i.v.) after bivagotomy and propranolol treatment, or intracoronary (i.c.) in the sinus node blood supply. Under these conditions the intervention of reflex reactions was eliminated, and a constant and dose-dependent negative chronotropic effect was obtained. From the dose-response curves the relative potencies of ATP and adenosine were calculated, and found to be similar for both routes of administration (potency ratio 0.77 (0.72-0.82) by i.v. administration, and 0.52 (0.36-0.78) by intracoronary administration). The effect was also mimicked by 2-chloroadenosine, (a long acting P1 agonist), and by 5'-adenylyl (beta, gamma-imido) diphosphonate, a non-hydrolysable ATP analog. The chronotropic effect of ATP and adenosine were not prevented by 1 mg/kg atropine intravenous. Theophylline, at 3 mg/kg i.v., shifted the dose-response curves of i.v. ATP and adenosine to the right, suggesting a competitive antagonism. At a dose of 6 mg/kg theophylline, the effects of i.c. adenosine were competitively blocked. Theophylline also antagonized, in a competitive manner, the hypotensive effect of the i.v. administration of both compounds. Our results suggest that the chronotropic effect of purine compounds in anaesthetized animals could be brought about by a specific purinergic theophylline-sensitive mechanism and not by direct vagal activation.

Adenosine↗
PubMedDate not supplied

[Management of difficult cases of biliary lithiasis].

UNLABELLED: To assess that insertion of a biliary endoprosthesis is a safe and effective treatment in patients with retained common bile duct stones (CBDS). BACKGROUND: Before 1974, surgical exploration including cholecystectomy with choledochotomy was the only effective treatment for CBDS. However, morbi-mortality increases rapidly in the elderly and is over 10% in patients over 65, particularly if other serious medical conditions are present. Endoscopic sphincterectomy is now an established procedure, with a success rate of about 90%, complications are relatively rare, and mortality is about 1%. However, the size and number of the stones, the appearance of the terminal bile duct and presence of peripapillary diverticulum influence the outcome. At the present time technique of fragmenting the stones using intracorporeal electrohydraulic, extracorporeal shock waves or laser lithotripsy would be seen to be an attractive alternative approach. Endoprosthesis insertion is a safe, effective and cheap treatment in CBDS. PATIENTS, METHODS AND RESULTS: 40 patients with unextractable CBDS were studied and treated with endoscopic stenting. Four patients were lost for follow-up. The remaining patients comprised 29 females and 7 males, with a mean age of 67 years. Four patients underwent surgical treatment for post-sphincterotomy haemorrhage (1 patient), internal endoprosthesis migration (1 patient) and peripapillary diverticulum (2 patients). In 7 high-risk patients with large CBDS, recurrent obstructive jaundice was successfully treated by replacing the endoprosthesis. In 6 of them we added medical treatment with ursodeoxycholic acid and after 24 months follow-up, the stones disappeared. In 13 patients the endoprosthesis were inserted temporally, and in a second approach we removed the CBDS by mechanical lithotripsy. The remaining 12 patients were still alive without symptoms after a follow-up of 24 months. CONCLUSIONS: On the basis of these findings we therefore concluded that endoscopic insertion of a biliary endoprosthesis is a safe and effective treatment for CBDS in patients in whom endoscopic sphincterotomy and attemps to remove the stones are not successful.

Adult↗
PubMedDate not supplied

[Extraction of foreign bodies in the esophagus. Experience in 215 cases].

OBJECTIVE: To analyze our experience in management of foreign bodies in esophagus. BACKGROUND: At present, the flexible endoscope is usually the instrument of choice for foreign bodies of the esophagus. The rigid endoscope is less expensive, but the advantages of the flexible endoscope are numerous. MATERIAL, METHODS: Management of 215 foreign bodies of esophagus are reported. The flexible endoscope was used to manage these foreign bodies. The patients comprised 151 children and 64 adults. RESULTS: In children, coins were the commonest foreign bodies (119 cases), whereas in adults, the commonest cause was impacted meat (35 cases). Two hundred fourteen foreign bodies (99.5%) were successfully managed endoscopically. The surgery rate was 0.5%. There was no morbidity or mortality. In fifteen adults we diagnosed significant associated medical conditions: benign esophageal stricture in eleven, esophago-gastric junction carcinoma in one, two patients with esophageal motility disorders and remaining with Plummer-Vinson Syndrome. CONCLUSIONS: The forward-viewing flexible endoscope has became the instrument of choice in diagnosis and management of esophageal foreign bodies.

Adolescent↗
PubMedDate not supplied

[Palliative treatment of esophageal cancer with transendoscopic injection of alcohol].

BACKGROUND: Few patients who present with dysphagia from esophageal cancer are curable. The rates of surgical resecability are low and the reported 5-yr survival rates are < 10%. Nonsurgical, endoscopic palliation of obstructing gastrointestinal cancers has became popular with stents, Nd: YAG laser, BICAP tumor probe, self-expanding metallic stents. Because of limited availability and extraordinary cost of equipment, most gastrointestinal endoscopy units can't afford their acquisition. Endoscopic injections of ethanol are useful for palliation of malignant dysphagia. AIMS: To examine if injections of ethanol are useful, in our patients, for palliation of malignant dysphagia. PATIENTS, METHOD AND RESULTS: Six male patients with dysphagia caused by inoperable or unresecable esophageal cancer were treated by endoscopic injection of ethanol to induce tumor necrosis. Prior to treatment, patients had a mean dysphagia grade of 3.6. After treatment, an optimum dysphagia grade (mean 0.8) was achieved with a mean of 6 injections treatments. There were no complications associated with endoscopic injection of ethanol. Mean patient survival rate was 286 days (range: 36-973). CONCLUSIONS: These results suggest that injections of ethanol to induce tumor necrosis have considerable potential for palliation of malignant dysphagia in patients with exophytic neoplasm.

Adult↗