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Biomedical subjects

J L Merino

Publications and source records attributed to J L Merino.

At least 19 recordsLinked to original sources
PubMed2006

[Urea distribution volume calculated by ionic dialysance].

BACKGROUND: Direct dialysis quantification is considered the gold standard for determining urea distribution volume, but it is impractical for routine use. So, urea distribution volume in hemodialysis patients is usually estimated from anthropometric equations. Ionic dialysance allows to calculate the urea distribution volume dividing the Kt obtained by ionic dialysance by the Kt/V obtained by a simplified formula. The aim of the present work was to analyse the concordance between the ionic dialysance and the direct dialysis quantification methods to estimate de urea distribution volume. MATERIAL AND METHODS: In 15 hemodialysis patients (10 males and 5 females), we have estimated the urea distribution volume by the direct dialysis quantification (Vurea), by the anthropometrics equations of Watson (VWatson) and Chertow (VChertow) and by the ionic dialysance method (VDI). To obtain VDI we have used two simplified Kt/V formulas: the monocompartimental and the equilibrated Daugirdas equations (VDIm and VDIe respectively). The intermethod variability was assessed by the relative difference (absolute difference between VUrea and the other methods, divided by the mean). RESULTS: VUrea (26,2 L) was statistically different from theVDIe (30,6 L, p < 0.01), VWatson 35.2 L (p < 0.001) and VChertow (38 L, p < 0.001). VDIm was 26.3 L (p = ns). VUrea represents the 42% of the body weight for the males (range 36 to 49%) and the 33% of the body weight for the female (range 28 to 38%). The intermethod variability was high for the VDIe (21.6%), VWatson (37.4%) and VChertow (48. 1%), but it was low for the VDIm (9.9%). CONCLUSIONS: Urea distribution volume calculated by the ionic dialysance method using the monocompartimental Daugirdas Kt/V equation has an acceptable agreement with the urea distribution volume calculated by the direct dialysis quantification. Anthropometry-based equations overestimate the urea distribution volume in hemodialysis patients.

Adult↗
PubMed2006

[Temperature dialysate and hemodialysis tolerance].

In this study, the effect of dialysate temperature on hemodynamic stability, patients' perception of dialysis discomfort and postdialysis fatigue were assessed. Thirty-one patients of the morning shift were eligible to participate in the study. Three patients refused. Patients were assessed during 6 dialysis sessions: in three sessions the dialysate temperature was normal (37 degrees C) and in other three sessions the dialysate temperature was low (35.5 degrees C). To evaluate the symptoms along the dialysis procedure and the postdialysis fatigue, specific scale questionnaires were administered in each dialysis session and respective scores were elaborated. Low temperature dialysate was associated with higher postdialysis systolic blood pressure (122 +/- 24 vs. 126 +/- 27 mmHg, p < 0.05), and lower postdialysis heart rate (82 +/- 13 vs. 78 +/- 9 beats/min, p < 0.05) with the same ultrafiltration rate. Dialysis symptoms score and postdialysis fatigue score were better with the low dialysate temperature (0.7 +/- 0.9 vs. 0.4 +/- 1 vs. p < 0.05, and 1.3 +/- 1 vs. 1 +/- 0.9 p < 0.05, respectively). Furthermore, low temperature dialysate shortened the post-dialysis fatigue period (5.4 +/- 6.3 vs. 3.1 +/- 3.3 vs. hours, p < 0.05). The clinical improvement experimented with the low temperature dialysate was not universal. A beneficial effect was exclusively observed in the patients with higher dialysis symptoms and postdialysis fatigue scores or having more than one episode of hypotension in a week. The patients were asked about their temperature preference, 7 patients (23%) request a dialysate at 37 degrees C, 19 patients (61%) prefered to be dialysed with the low temperature dialysate, and 5 patients (16%) were indifferent. The later two groups of the patients continued with the low temperature dialysate during other 4 weeks. At the end of that period, the clinical improvement remained unchanged. In summary, low temperature dialysate is particularly beneficial for highly symptomatic patients.

Adult↗
PubMed2004

[Therapy with interferon plus ribavirin in hemodialysis patient with PCR-positive viral hepatitis C].

Traditionally, the treatment of viral hepatitis C (positive Polymerase Chain Reaction -PCR-) was with Interferon. A combination of Interferon plus Ribavirin has been producing better results in last years. Currently, Ribavirin is not indicated for patients with Chronic Kidney Disease because of a high risk of severe anaemia. In a few cases, this treatment is producing good results with previous dose adjustment. We show a case of a 28-year-old man with Chronic Kidney Disease on treatment with periodical hemodialysis and chronic hepatopathy HCV Positive RNA HCV (> 1,000,000 copies/ml) and persistent transaminase elevation. Before kidney transplantation, we decided to use Interferon (3,000,000 IU/48 hours) and Ribavirin (200 mg/24 hours) treatment. After 15 days, we saw normal transaminase values and HCV RNA was negative. The patient required temporary suspension of Ribavirin and two red blood cell transfusions due to severe anaemia. Ribavirin was reintroduced 200 mg/48 h posthemodialysis. The patient did not present any complication again, and could be treated for 14 months. After next 11 months of evolution the patient has normal rates of liver function and negative HCV RNA values.

Adult↗
PubMed2004

[Membranous nephropathy associated to autoimmune thyroiditis, chronic pancreatitis and suprarrenal insufficiency].

A 33 year old female was admitted to the hospital to study aedema and bocio, A nephrotic syndrome was diagnosed and the renal biopsy demonstrated membranous glomerulonephritis, stage II. She was also diagnosed of Hashimoto's autoinmmune thyroiditis: TSH (41.5 uUl/ml), T4 (0.07 ng/dl), antithyroglobuline (1/2560) and antimicrosome (1/6400). Four year latter she was diagnosed of autoinmmune pancreatitis, without evidence of diabetes mellitus or exocrine pancreatic insufficiency. Eight years latter she was diagnosed of primary autoimmune suprarrenal insufficiency: basal cortisol: 2.7 mcg/dl, post ACTH estimulated cortisol: 5.6 mcg/dl, antinuclear antibody (1/160) and antiparietal (1/320). We present a pluriglandular autoimmune syndrome with membranous glomerulonephritis, thyroiditis, pancreatitis and suprarrenal insufficiency. To the best of our knowledge this complex syndrome has not been previously described.

Adrenal Insufficiency↗
PubMed2001

Bundle-branch reentry and the postpacing interval after entrainment by right ventricular apex stimulation: a new approach to elucidate the mechanism of wide-QRS-complex tachycardia with atrioventricular dissociation.

BACKGROUND: Diagnosis of bundle-branch reentry ventricular tachycardia (BBR-VT) by the standard approach is challenging, and this may lead to nonrecognition of this tachycardia mechanism. Because the postpacing interval (PPI) after entrainment has been correlated with the distance from the pacing site to the reentrant circuit, BBR-VT entrainment by pacing from the right ventricular apex (RVA) should result in a PPI similar to the tachycardia cycle length (TCL). This factor may differentiate BBR-VT from other mechanisms of wide-QRS-complex tachycardia with AV dissociation, such as myocardial reentrant VT (MR-VT) or AV nodal reentrant tachycardia (AVNRT), in which the circuit is usually located away from the RVA. METHODS AND RESULTS: Transient entrainment by RVA pacing was attempted in 18 consecutive BBR-VTs and finally achieved in 13. Results were compared with those found in 59 consecutive MR-VTs and 50 consecutive AVNRTs. The mean PPI-TCL difference was significantly (P:<0.0001) shorter in the BBR-VT group (9+/-11 ms) than in the MR-VT (109+/-48 ms) and the AVNRT (150+/-29 ms) groups. No BBR-VT showed a PPI-TCL >30 ms (range -12 to 24 ms). Except for 2 MR-VTs, no MR-VT (range 21 to 211 ms) or AVNRT (range 100 to 215 ms) showed a PPI-TCL <30 ms. CONCLUSIONS: A PPI-TCL >30 ms, after entrainment by RVA stimulation, makes BBR-VT unlikely. Conversely, a PPI-TCL <30 ms is suggestive of BBR-VT but should lead to further investigation by use of conventional criteria.

Bundle-Branch Block↗
PubMed2001

Decremental atriofascicular accessory pathway with bidirectional conduction: delineation of atrial and ventricular insertion by radiofrequency current application.

A 17-year-old girl with a corrected complex congenital heart disease and recurrent episodes of supraventricular tachycardia was referred for catheter ablation. Electrophysiologic studies revealed the presence of an accessory pathway (AP) with bidirectional conduction and decremental properties. We demonstrated a course parallel to the node-His AV conduction system. Transient abolition of the bidirectional conduction through the AP was obtained by radiofrequency application to the ventricular insertion located in the distal right bundle branch and to the atrial insertion, located in the mid-anterior atrial septum. Radiofrequency application at the low anterior atrial septum, above the His bundle, successfully abolished AP conduction without affecting AV nodal conduction. Demonstration of the course and insertions of the AP, its bidirectional decremental conduction properties, and the association with a complex congenital heart disease are exceptional and interesting findings and raise the possibility of an accessory AV node with a parallel conduction pathway to the right bundle branch.

Adolescent↗
PubMed2001

Mechanisms underlying ventricular arrhythmias in idiopathic dilated cardiomyopathy: implications for management.

Ventricular arrhythmias (VA) have been associated with mortality in idiopathic dilated cardiomyopathy (IDCM). All 3 main mechanisms of arrhythmogenesis - reentry, trigger activity, and automatism - have been implicated. Arrhythmogenic substrates in IDCM favor these mechanisms and are often potentiated by electrolyte imbalance secondary to diuretic treatment, by antiarrhythmic drugs, or by bradycardia, leading to polymorphic ventricular tachycardia (VT). Myocardial macroreentry is the mechanism most frequently responsible for monomorphic VT in IDCM; however, focal activation and His-Purkinje macroreentry are often responsible and, especially in the latter case, are frequently unrecognized. Clinical suspicion and final recognition by electrophysiologic testing have important therapeutic consequences, because both focal activation and His-Purkinje macroreentry can be treated effectively by catheter ablation. On the other hand, the frequent recurrences of myocardial macroreentrant VT after ablation require this therapy to be used in combination with drugs or an implantable cardioverter defibrillator (ICD). beta-Adrenoceptor antagonists (beta-blockers) have a beneficial effect for primary prevention of VA in IDCM. Type III antiarrhythmics have a neutral effect on mortality and type I antiarrhythmics should be avoided. Treatment of nonsustained VT in IDCM is controversial because it often presents without symptoms and is linked more to overall mortality than to arrhythmic mortality. Empiric treatment with amiodarone or electrophysiologically guided sotalol are preferred to the use of other drugs for secondary prevention of sustained VA. ICDs should be implanted in patients who have been resuscitated from cardiac arrest due to VA, or in those with poorly tolerated VT and severe left ventricular dysfunction. Empiric treatment with amiodarone or electrophysiologically guided class III antiarrhythmics may also be alternatives for patients with IDCM and no severe left ventricular dysfunction, especially if VT is well tolerated.

Adrenergic beta-Antagonists↗
PubMed2000

[Cardioinhibitory vagal response not related to pain, and induced by radiofrequency application during ablation of right posteroseptal accessory pathway].

Inappropriate sinus tachycardia is the most common arrhythmia induced by radiofrequency energy delivery in the posteroseptal area. It has been suggested that this could be secondary to parasymphathetic nerve injury. We report a patient with extreme sinus bradycardia and PR interval prolongation induced by radiofrequency energy delivered in the coronary sinus ostium area, but not related to any other stimulus. The most probable mechanism of the disorder was transient stimulation of the vagal afferent nerve fibers located in this anatomical area.

Autonomic Pathways↗
PubMed2000

[Oblique orientation of the accessory pathway demonstrated by radiofrequency application].

Activation mapping of atrial and ventricular insertion has suggested an oblique orientation of some accessory pathways. However, this aspect has not been demonstrated by radiofrequency application. This report presents two patients with Wolff-Parkinson-White syndrome and an accessory pathway with bidirectional conduction and oblique orientation. The accessory pathway oblique orientation was demonstrated by transient and permanent conduction abolition following radiofrequency application in two separate ventricular and atrial sites. These findings may explain the failure to ablate accessory pathway by radiofrequency application in the ventricular side of the mitral annulus guided by retrograde atrial activation occasionally observed in patients with a concealed accessory pathway.

Catheter Ablation↗
PubMed2000

Ablation of idiopathic ventricular tachycardia by bipolar radiofrequency current application between the left aortic sinus and the left ventricle.

BACKGROUND: Failure to ablate idiopathic ventricular outflow tract tachycardia by radiofrequency current is not uncommon and suggests that non-standard approaches may be required to map and suppress idiopathic ventricular tachyarrhythmias in some patients. METHODS AND RESULTS: Left and right ventricular activation and pace mapping proved inadequate for radiofrequency application in a patient with idiopathic ventricular outflow tract tachycardia. Presystolic activity was recorded at the left aortic sinus of Valsalva, and the QRS complex recorded at this location during pacing showed few differences compared with that recorded during tachycardia. Radiofrequency current application at this site transiently suppressed the tachycardia. Following new mapping of the left ventricle outflow tract, radiofrequency application just below the aortic valve in close proximity to the previous aortic application site transiently abolished the arrhythmia. Finally, bipolar radiofrequency application between the distal electrode of the aortic catheter and the distal electrode of a second catheter placed in the left ventricular subaortic area permanently suppressed the tachycardia. CONCLUSION: Bipolar radiofrequency application between the aortic sinus of Valsalva and the left ventricle could be an alternative approach in occasional patients with idiopathic ventricular outflow tract tachycardia resistant to conventional left ventricular and aortic root unipolar radiofrequency application.

Aged↗
PubMed2000

[Coxiella burnetii endocarditis: long-term clinical course in 20 patients].

INTRODUCTION AND OBJECTIVES: Coxiella burnetii is a causative agent of increasingly frequent subacute infective endocarditis, and is associated with elevated morbimortality. Our aim in the present study was to assess the clinical, serological and therapeutic long-term evolution of 20 patients with Coxiella burnetii endocarditis. METHODS: Twenty patients (13 male and 7 female, age 42 +/- 10 years) admitted between 1982 and 1996 were retrospectively studied. All of them fulfilled the Duke criteria modified by Raoult for Q fever endocarditis. RESULTS: Endocarditis involved prosthetic and native valves in 14 and 6 patients, respectively. All patients except one received antibiotic treatment. Patients treated with doxycycline in monotherapy showed worse evolution than those treated with doxycycline in combination with other antibiotics. Valve replacement was performed in 15 patients, due to prosthetic dysfunction in most of them. The overall mortality was 40% (8 patients). At follow-up of 74 months (range 19-156) (mean 74 +/- 47) all patients showed persistent high levels of phase I antibodies. At follow-up of 15 to 65 months (32 +/- 30) antibiotic treatment was suspended in five patients because they were asymptomatic and without microbiologic findings of valvular endocarditis. CONCLUSIONS: Q fever endocarditis was associated with severe complications, which often required valve replacement. All patients showed persistent high serological titers of Coxiella burnetii endocarditis without other signs of active infection. This finding raises the issue of suspending antibiotic treatment in patients with negative microbiologic findings and questions the persistence of abnormal serology as a monitor of treatment efficacy.

Adult↗
PubMed1999

Transient entrainment of bundle-branch reentry by atrial and ventricular stimulation: elucidation of the tachycardia mechanism through analysis of the surface ECG.

BACKGROUND: Different responses to entrainment have been reported in relation to the pacing site of a variety of tachycardias. However, transient entrainment of bundle-branch reentrant tachycardia (BBRT) has not been investigated systematically. METHODS AND RESULTS: We attempted entrainment of 13 BBRTs in 9 patients by pacing first the right ventricle and then the right atrium. The initial pacing cycle length (CL) was 10 ms faster than the tachycardia CL. Subsequent pacing sequences were performed with 5- to 10-ms CL decrements until tachycardia termination or loss of postatropine 1:1 AV conduction. Both full ventricular-paced and AV-conducted QRS complex references were obtained during sinus rhythm pacing from the same sites and with similar CL as during entrainment. Transient entrainment was achieved by ventricular and atrial stimulation in 11 and 8 tachycardias, respectively. Constant fusion was always present during entrainment by ventricular stimulation. There was no change in the QRS complex (orthodromically concealed fusion) during entrainment by atrial stimulation in 6 of 6 tachycardias with left bundle-branch block morphology and in 1 of 2 tachycardias with right bundle-branch block morphology. CONCLUSIONS: BBRT, especially if it has a left bundle-branch block morphology, can be differentiated from other wide-QRS-complex tachycardia mechanisms through analysis of the ECGs recorded during tachycardia entrainment by atrial and ventricular stimulation. This diagnostic approach may be especially useful when it is difficult to record a stable or sufficiently sized His bundle electrogram or when spontaneous changes in the ventricular CL precede similar changes in the His bundle CL.

Adult↗
PubMed1999

Characterization of a new HLA-B*38 allele (B*3803) in a Spanish Caucasian individual which is closely related to the Oriental B*38021 and B*39021 alleles.

The broad HLA-B16 serologic specificity is divided into B38 and B39 splits associated to Bw4 and Bw6, respectively. Differential serologic variants have been defined for several molecular subtypes of B39 and for B38. We found a Spanish Caucasian individual carrying a B16 Bw4-associated antigen which was not recognized by reagents against B16 splits. Sequencing analysis showed a new B16 subtype termed B*3803. HLA class I sequence-based typing (SBT) analysis demonstrated that B*3803 co-segregates with A*2608 and Cw*1203, forming a common Caucasian haplotype. Sequence comparison with B*38 and B*39 subtypes evidences that although B*3803 is close related to B*3802, it only differs from B*39021 by six clustered nucleotide position in the Bw4/Bw6 motif, and strongly suggests that B*3803 could have evolved from, or be the ancestral gene of the Oriental-associated B*3802 and B*39021 alleles. However, more complex patterns of genetic events should be considered due to the Caucasian background of the B*3803 individual an its associated haplotype.

Alleles↗