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Biomedical subjects

L Colín

Publications and source records attributed to L Colín.

36 records · Page 2Linked to original sources
PubMedDate not supplied

[Value of the exercise test in asymptomatic myocardial ischemia].

To evaluate the predictive value of ischemic ST segment depression without associated chest pain during exercise testing, data were analyzed from 7305 studies. Two hundred thirty six patients were included in this study and were separated in 2 groups. Group A consisted of 169 patients without chest pain who, during exercise testing, showed a positive ST segment response (at least 1.5 mm of horizontal or downward ST segment depression for at least 0.08 second, compared with the resting baseline value), and Group B consisted of 67 patients who had both chest pain and a positive ST segment response. Selective coronary angiogram was performed on all patients. Each Group was separated into 3 sub-group according to the Cohn criteria: sub-group I (asymptomatic persons 8.3 vs 19.4%); sub-group II (patients with history of Myocardial Infarction 36.7% vs 19.4%); sub-group III (patients with chronic angina 55% vs 61.2%). The clinical characteristics, coronary risk factors, distribution of coronary artery disease, and exercise test response were similar in both groups. During treadmill exercise, the mean heart rate was 140.6 +/- 22 in group A versus 127.1 +/- 23 in the group B. The pressure-rate product was 2.4 +/- 0.8 versus 1.9 +/- 0.5, respectively (P less than or equal to 0.05). The predictive value for severe coronary artery disease of an exercise test in patients with asymptomatic ischemia was 77.5% as compared with 89.6% in the group with angina. This study confirms the high frequency of asymptomatic myocardial ischemia during exercise testing, compared with patients who had angina during exercise testing, with high percentage of prediction (77.5%) for coronary artery disease.

Aged↗
PubMedDate not supplied

[Myocardial infarct immediately after a normal exercise test].

Two cases of myocardial infarction immediately following a normal stress testing, are described. The incidence and possible pathophysiological mechanisms are discussed. In one of the patients it was difficult to establish the pathophysiological mechanism which was the cause of the ischemic event. In the other, the coronary arteriography revealed only minimal obstructive disease. Therefore, coronary vasospasm with thrombus formation as a cause of the infarction ia an interesting speculative possibility in view of the angiographic findings. Acute myocardial infarction after a normal electrocardiographic response to maximal exercise testing is extremely rare, and the precise pathophysiologic mechanism that leads to his complication is not clear.

Adult↗
PubMedDate not supplied

[Usefulness of the pre-excitation index to determine the mechanism of supraventricular paroxysmal tachycardia and the location of the anomalous pathway].

To evaluate the preexcitation index in determinate the mechanism of paroxysmal supraventricular tachycardia and localize accessory pathway, fifty nine patients with clinical and electrocardiographic supraventricular tachycardia were analyzed. There were thirty eight patients (64.4%) with orthodromic AV reentry using an accessory pathway for retrograde conduction and 21 patients (35.6%) with typical AV nodal reentrant tachycardia. Preexcitation of the atrium during tachycardia by premature ventricular complex at a time when anterograde His bundle activation was present in 30 o 38 (79%) patients with AV reentry while only 8 of 21 (38%) patients with AV nodal reentry demonstrated preexcitation during tachycardia. There was no significant difference between left and right accessory pathways and in mean tachycardia cycle length between the two groups. However, atrioventricular reentry demonstrated atrial preexcitation during tachycardia more frequently than AV nodal reentry. In conclusion, our findings show that the preexcitation index is a useful method for determinate the mechanism of supraventricular tachycardia and to localize accessory pathways.

Adolescent↗
PubMedDate not supplied

[Wolff-Parkinson-White syndrome with orthodromic supraventricular tachycardia associated with a "hyper-conductor" atrio-ventricular node. A therapeutic challenge].

One case of Wolff-Parkinson-White Syndrome with paroxysmal supraventricular tachycardia related to orthodromic atrioventricular reentry using an accessory pathway for retrograde conduction an a rapidly conducting AV node for anterograde conduction is present. The pharmacological therapy with Digoxin, Propranolol, Quinidine, Disopyramide and Propafenone was not effective. An electrophysiologic study showed a reciprocating tachycardia induced by spontaneous ventricular beats. Both the effective refractory period of the AV node and the anterograde effective refractory period of the accessory pathway were minor or equal to 220 msec which made the control of the arrhythmia difficult. Amiodarone was able to suppress the premature ventricular beats, depress conduction and prolong refractoriness in both, the AV node and accessory pathway to prevent recurrences of atrioventricular reentry. In this patient a false positive test with ajmaline was documented. The electrophysiologic study showed the association of Wolff-Parkinson-White Syndrome with an enhanced atrioventricular nodal-conduction and allowed the selection of an appropriate antiarrhythmic agent.

Adult↗
PubMedDate not supplied

[Electrofulguration of a pre-excitation zone by the bundle of Kent].

The purpose of this presentation is to report the first endocardial catheter ablation in Mexico of a right posteroseptal accessory pathway. The patient, without structural heart disease, had a Wolff Parkinson White syndrome with recurrent episodes of paroxysmal supraventricular tachycardia and atrial fibrillation with a fast ventricular response, through the accessory pathway (Shorter RR interval less than or equal to 190 msec). Previous antiarrhythmic drug therapy had failed to control the tachyarrhythmias. An electrophysiologic study was performed and the right posterior septal accessory pathway was localized by direct mapping of the auriculoventricular junction. Two sessions of electrofulguration with energy shocks ranging from 200 to 250 joules were delivered. There were no complications during the two procedures. Three months afterwards the patient is asymptomatic without tachyarrhythmic episodes, and no drug therapy is necessary. The fulguration prolonged the anterograde accessory pathway conduction. Therefore, the risk of sudden cardiac death due ventricular fibrillation has been reduced.

Adult↗
PubMedDate not supplied

[Clinical electrophysiological evaluation of mexiletine].

We studied sixteen patients (pts), seven men and nine women (mean age 35 years) with sustained tachyarrhythmias, for acute therapeutic trial with mexiletine (3 mg/kg IV). The arrhythmias were: ventricular tachyarrhythmia in eight pts supra-ventricular tachycardia (SVT) in eight pts, seven due to abnormal tracts (43%) and one to nodal reentry. After mexiletine administration, the sinusal cycle length was reduced in 12.7% (P less than 0.05) and the H-V interval decreased 6.1% (P less than 0.05). The nodal conduction (A-H) didn't show any substantial change, neither the atrial nor the ventricular refractory periods (RP). In two pts with complex premature ventricular beats it was not possible to induce the ventricular tachycardia(VT) six had sustained VT. After mexiletine administration, three of them (37.5%) showed self limited VT with a greater R-R cycle. Another case was complicated by ventricular fibrillation, In the pts with SVT, the retrograde RP of the abnormal tracts shortened in 27% (P less than 0.05), while the antegrade was not modified. Mexiletine showed to be efficient for the VT treatment. Its efficacy was very limited in pts with SVT. There was no evidence of any deleterious effect over the His-Purkinje conduction.

Adolescent↗
PubMedDate not supplied

[Continuous electrocardiographic recording during a first parachute jump].

The behavior of the cardiac rhythm under intense stress was studied with continuous electrocardiographic recording during the first jump with an automatic parachute in 13 members of the Universidad Nacional Autónoma de México sky diving club. There were 12 male (92.3%) and one female (7.68) with an average age of 22.8 years. A complete clinical history, 12 lead electrocardiogram and a treadmill stress test were performed two weeks before jumping. A two-channel Holter recording system was hooked up 30 min. before boarding the airplane and was turned off one hour later. The heart rate values were compared two weeks prior (64.5 beats/min), before (112.8 beats/min), during (170 beats/min) and after the jump (122.8 beats/min). The mean difference between each phase was statistically significant with p less than 0.001 values. The observed cardiac rhythm was sinus tachycardia in each case. In six cases (43.6%) 22 episodes of sudden decrease of the heart rate were seen and there were no major rhythm or conduction disturbances. The urinary catecholamines were similar in nine cases (69.2%) after the jump (x 51.2 micrograms/100 ml) and two weeks later in four control cases (x 10.3 micrograms/100 ml). We concluded there were no significant rhythm disturbances in the presence of an intense but brief stress condition in young healthy people. This study was classified as longitudinally, descriptive, experimental and projective.

Adult↗
PubMedDate not supplied

[Topographic diagnosis of atrio-ventricular conduction defects].

Atrioventricular (A-V) conduction was evaluated in 51 patients who underwent electro-physiological study. Eighteen patients had nodal conduction delay (A-H greater than 150 ms), six of them were congenital, in two others it was associated to a His-Purkinje (H-V) delay. None of them had bundle branch block in the surface ECG. The conduction delay was located within the his bundle in 15 patients (29.4%). In three of them, a split His bundle electrogram was recorded; in the other 12 (80%), His bundle stimulation normalized QRS morphology; in all of these patients H-V interval was longer than 70 ms. His bundle delay was associated to infra H lesion in five patients. In one without ECG changes, atrial and His bundle stimulation demonstrated a left troncular delay with a distal block in the right bundle branch. Thirteen patients had infra His block represented by a long H-V interval (greater than 60 ms). We conclude that His bundle electrograms and stimulation is a low risk procedure very useful in the topographic diagnosis of A-V conduction disturbances.

Adolescent↗
PubMedDate not supplied

[Radiofrequency ablation in tachycardias due to accessory pathways in a pediatric population].

Catheter ablation of accessory atrioventricular pathways using radiofrequency current was attempted in 61 children and young adolescents less than 18 years of age who were referred for treatment of symptomatic supraventricular tachycardia. Thirty-three children had the Wolff-Parkinson-White syndrome and 30 tachyarrhythmias related to an accessory pathway conducting only in retrograde fashion. Ablation of left sided accessory pathways was usually attempted utilizing an arterial approach to the annulus of the mitral valve, only in one case we used the transseptal approach, while the venous route to the atrial aspect of the tricuspid valvular annulus was chosen for right sided accessory connections. Ablation of 55 of 63 accessory connections was achieved (87% success) with a range of 1 to 42 applications of radiofrequency current. The sessions were completed within 19 to 180 minutes, and we used within 16 to 45 watts of radiofrequency current. Two patients had complications as a result of their ablation procedure. One patient had complete heart block but did not require pacemaker implantation, and other one had mitral regurgitation. A second session was necessary in three patients, two of three accessory pathways were ablated, giving a success rate of 90%. During a one year period of follow-up, we had 4 recurrences (7.2%). Catheter ablation using radiofrequency current is a highly effective and safe curative approach for treating young patients with supraventricular tachycardia mediated by accessory pathways.

Adolescent↗
PubMedDate not supplied

[Radiofrequency ablation in idiopathic ventricular tachycardia originating in the right ventricle].

We present the case of a 10-year-old boy, with structurally normal heart who began two years before admission, with sustained monomorphic ventricular tachycardia with heart rate of 280 bpm and LBBB morphology, AQRS + 60 degrees, with pallor and diaphoresis. The tachycardia was treated with xylocain. He was also treated with propaphenone, verapamil, and amiodarona, in spite of these, he continued with this type of arrhythmia 2 or 3 times a month. We performed an electrophysiologic study which showed ventricular tachycardia originated in the right ventricle infundibulum. We took an endomyocardial biopsy, which was normal. He was scheduled for percutaneous catheter ablation of the tachycardia by radiofrequency energy. During the procedure the ventricular tachycardia appeared spontaneously, we mapped the most early ventricular activation and then in sinus rhythm, this site was pace mapped and resulted in similar pattern of clinical ventricular tachycardia. We identified the site of origin of the ventricular tachycardia in the posterior region of the right ventricle infundibulum, delivering radiofrequency, changing to sinus rhythm. Then we paced the apex of the right ventricle without inducing any form of arrhythmia. He is asymptomatic four months later.

Cardiac Pacing, Artificial↗
PubMedDate not supplied

[Radiofrequency ablation of an accessory left lateral pathway in an infant, using a transeptal approach].

We describe the case of a 4 month old child with supraventricular tachycardia detected on his second day of life, refractory to medical treatment, who was treated with radiofrequency catheter ablation of an accessory auriculoventricular pathway located on the left lateral wall. A venous femoral approach was used and the left atrium was entered through a patent foramen ovale, avoiding the risks of the arterial puncture and allowing us to administrate the radiofrequency current on the proper site. We discuss the potential risks of the therapeutic procedure in children and the benefits of the transeptal over the retrograde approaches for the treatment of left sided accessory pathways. Our conclusion is that catheter radiofrequency ablation of accessory pathways in children is possible with low risk, which can be diminished with the use of the transseptal approach when indicated.

Catheter Ablation↗
PubMedDate not supplied

[Identification of patients at risk of malignant arrhythmia in the 1st year after myocardial infarction].

Two hundred twenty two consecutive patients with acute myocardial infarction were followed for one year. We evaluated the usefulness of late potentials, the spectral analysis, heart rate variability, infarct-related coronary artery, ejection fraction, arrhythmias during Holter monitoring and other clinical variables as risk markers for developing of ventricular arrhythmias and/or sudden death. Twenty four patients (10.8%) had late arrhythmic events: sudden death in 7, sustained ventricular tachycardia in 15 and unexplained syncope in 2. Late potentials had high sensitivity (94%) and negative predictive value (99%), followed by an occluded related-infarct coronary artery (75% sensitivity and 96% negative predictive value). Complex ventricular arrhythmias during Holter monitoring was the test with the highest specificity (92%). A combination of late potentials plus an occluded infarct-related coronary artery or late potentials plus ejection fraction showed 100% sensitivity with 100% negative predictive value. Of the 16 studied variables, 5 had independent and significative value as a predictor of arrhythmic events, these are, according to the relative risk: late potentials (20.2), ejection fraction less than 40% (12.1), complex arrhythmias during Holter monitoring (7.5), the presence of an occluded infarct-related coronary artery (6.4) and anterior myocardial infarction localization (4.5). We consider, that with a combination of simple methods of assessment, we can select a subgroup of survivors of an acute myocardial infarction at high risk of developing ventricular arrhythmias and sudden death, which also identifies patients with low risk for these complications.

Aged↗
PubMedDate not supplied

[The radiofrequency ablation of Mahaim and Kent fibers during the repair of Ebstein's anomaly].

A young man 20 years old was referred to the Institute with Ebstein anomaly. He had experienced palpitations since the age of eight. Those episodes occurred several times a year. During the electrophysiologic study a regular antidromic reciprocating tachycardia was induced using a right atriofascicular connection (Mahaim). The atrial insertion of the Mahaim fibers was in the right posterolateral atrium. Also another orthodromic supraventricular tachycardia was induced with anterograde conduction over atrioventricular node and retrograde conduction over to canceled atrioventricular right posteroseptal bypass tract (Kent). During surgery to repair Ebstein anomaly we decided to perform radiofrequency catheter ablation of both Mahaim and Kent fibers at the tricuspid annulus in the posteroseptal and lateral regions, eliminating accessory pathways conduction. There were no complications during the procedure. The tachycardia has not recur in a six months period of follow up. No antiarrhythmic drugs has been given.

Adult↗
PubMedDate not supplied

[The termination of auricular flutter by noninvasive programmed electrical stimulation using a permanent AAI-mode pacemaker].

We describe a case of a 15-year-old boy with an atrial septal defect who three years after the direct closure of the defect presented with atrial flutter type I according to Wells's classification. He was then electrically cardioverted but presented immediately sinus bradycardia and a ventricular escape rhythm that required epicardial pacing (Intermedics 292-03 DASH) in the AAI mode. We report here the successful termination of a new episode of atrial flutter into sinus rhythm with a noninvasive programmed stimulation using his previously implanted pacing system.

Adolescent↗
PubMedDate not supplied

[A comparative study between surgical section and radiofrequency ablation of the anomalous pathways in the WPW syndrome].

Radiofrequency catheter ablation is an effective alternative to medical therapy to patient with Wolff Parkinson White syndrome (WPW). The purpose of this study is to compare our results in 70 patients with WPW that underwent either surgery or ablation procedure with radiofrequency energy. Of this number of patients the surgical procedure was successful in 82%; complications were present in 15% and mortality in 8%. Average hospitalization was 6 to 10 days and cost from 2 to 10 thousand of new pesos. On the other hand, of 44 patients that underwent radiofrequency ablation, in 80% the procedure was finally successful with recurrence of 9% and no mortality. The hospitalization period was one day, the cost run from 500 to 2 thousand of new pesos in our institution. These results demonstrate the efficacy of the radiofrequency energy ablation in the treatment of WPW. This procedure is safe and less expensive than surgery.

Adolescent↗
PubMedDate not supplied

[The radiofrequency ablation of accessory pathways in 100 consecutive patients with supraventricular tachycardias].

The purpose of this study is to describe the results and the complications of radiofrequency catheter ablation, of accessory pathways in 100 consecutive patients. We had one patient with two pathways. Of the 101 accessory pathways, 56 were overt and 45 concealed. Only 19 patients have had a previous electrophysiology study, in the others, the study and the ablation were performed simultaneously. The location of the accessory pathways were as follows: 61 pathways in the free wall of the left ventricle, 4 in the free wall of the right ventricle, 25 in the left posteroseptal region, 9 in the right posteroseptal region and 2 in the right anteroseptal area. The time required for the diagnostic component of the electrophysiology study, the ablation procedure and the fluoroscopic time was recorded for each patient. Ninety-one of 101 accessory AV connections were successfully ablated (90%). Our success rate for the initial attempt was 87%. We had the opportunity to do a second attempt in only 4 out of 14 patients. The mean time of the procedure, including the electrophysiology test and the ablation was 95.6 %/-55.3 minutes. We have had a recurrence of 9% and 4% of non fatal complications. Radiofrequency catheter ablation can be performed safely and with a high success rate.

Adolescent↗
PubMedDate not supplied

[Radiofrequency ablation of type I atrial flutter: combination of electrophysiological and anatomical techniques].

Atrial flutter type I (FLA) is one of the most common arrhythmias found in clinical practice. Reentry into the right atrium (AD) is the mechanism of this arrhythmia. The reentry mechanism has critical sites where radiofrequency (RF) can act blocking the circuit. Both, electrophysiological and anatomical approaches using RF to FLA have demonstrated a success rate above 80%. Our group combined both techniques treating 35 patients with FLA type I (22 men and 13 women), with mean age of 40.8 +/- 15 years old (range 9-70). In 21 patients (60%) this arrhythmia was associated with cardiopathy. All patients had failed to respond to different antiarrhythmic therapy. The success rate was 82.8% (29/35). When compared failure vs success we observed that patients who failed were older (51.8 vs 38.5 years old, p < 0.05), had structural cardiopathy (83.3% vs 55.1%, p = NS), had FLA type I with P waves with shorter cycle length (195 vs 254 ms, p = 0.052), had the arrhythmia chronically (129.6 vs 68.1 month, p = NS), had great left atrium diameter (41.2 vs 36.7 mm, p = 0.052) and frequently had been associated with atrial fibrillation (33.3% vs 3.4%, p = 0.02). There were no complications. Six (20.6%) patients reverted to FLA. We followed our patients during mean time 8.37 +/- 8.8 months (1-36). Our results support the notion that FLA type I can be treated with high percentage of success and low risk of complications when both RF techniques are combined. Our predictors of failure were: gender and associated atrial fibrillation (p < 0.05). We conclude that RF is the treatment of choice in every patient with FLA type I who had failed to antiarrhythmic therapy. We recommend RF as soon as FLA has been diagnosed because the probability of success is higher in such instances.

Adolescent↗