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Biomedical subjects

J A Gomes

Publications and source records attributed to J A Gomes.

At least 19 recordsLinked to original sources
PubMed1996

Value of quantitative measurement of signal-averaged electrocardiographic variables in arrhythmogenic right ventricular dysplasia: correlation with echocardiographic right ventricular cavity dimensions.

OBJECTIVES: We sought to investigate the relation between signal-averaged electrocardiographic (ECG) variables and the extent of right ventricular disease, as estimated by right ventricular enlargement during detailed echocardiography, in patients with arrhythmogenic right ventricular dysplasia. BACKGROUND: In patients with ventricular tachycardia of right ventricular origin, a normal signal-averaged ECG is indicative of "idiopathic" ventricular tachycardia, whereas an abnormal signal-averaged ECG is a specific marker for right ventricular disease, especially dysplasia. Signal-averaged ECGs in these patients are mildly to grossly abnormal. METHODS: Ten patients with the clinical diagnosis of arrhythmogenic right ventricular dysplasia were included. All patients had documented, sustained ventricular tachycardia, no coronary artery disease and a normal QRS duration of < or = 110 ms on routine 12-lead electrocardiography. Signal-averaged ECGs were recorded using time-domain analysis. Right ventricular cavity dimensions recorded during two-dimensional echocardiography were measured at the level of the inflow tract, midcavity and outflow tract. Signal-averaged ECG variables and echocardiographic measurements were correlated using linear regression analysis. RESULTS: Nine of 10 patients had abnormal signal-averaged ECGs. There was a consistent correlation between all signal-averaged ECG variables and the right ventricular cavity dimensions at the level of the midcavity. The correlation was most significant with the duration of the filtered QRS complex (p < 0.001 for QRS duration, p < 0.01 for late potential duration and p < 0.05 for root-mean-square voltage of the last 40 ms). There was no consistent correlation between the signal-averaged ECG variables and right ventricular dimensions at the level of the inflow and outflow tracts. CONCLUSIONS: The majority of patients with arrhythmogenic right ventricular dysplasia have abnormal signal-averaged ECGs. In the absence of bundle branch block, the extent of abnormality of signal-averaged ECG variables is in proportion to right ventricular cavity enlargement, and thus is indicative of the severity of right ventricular dysfunction.

Adult↗
PubMed1996

Topographic stability and safety of contact lens use after penetrating keratoplasty.

PURPOSE: We evaluated long-term corneal topographic stability and the safety of contact lens use after penetrating keratoplasty (PK). METHODS: Over a period of 3 years, we followed 18 patients who had been fit with rigid gas permeable (RGP) contact lenses after PK on the basis of computerized topographic measurements 1.5 mm superior to the visual axis. Computerized corneal topography, keratometry, refraction, visual acuity, slit-lamp examination, and contact lens parameters were recorded at the time of lens fitting and at 3 years follow-up. Comparison between the two times was performed using the paired Student's t test. The ten patients (55.5%) that did not undergo suture removal after initial contact lens fitting and who did not change contact lens type during the follow-up period were considered eligible for topographic and keratometric evaluation. RESULTS: Absolute keratometric astigmatism, average keratometric values, computerized corneal topography measurements 1.5 mm superior to the visual axis, and inferior minus superior measurements did not reveal significant differences over time. Keratometric vector analysis showed a significant change in astigmatism during the study period. Complications observed in the 18 patients included suture infiltrates (two patients), corneal neovascularization (six patients), graft rejection (five patients), transitory punctate epithelial keratitis (eight patients), and giant papillary conjunctivitis (three patients). All were successfully treated topically and with temporary cessation of contact lens wear. CONCLUSIONS: RGP contact lens use after PK is safe provided patients are properly fit and followed by the ophthalmologist. Although corneal topographic changes occur, stability remains acceptable.

Adult↗
PubMed1996

Recurrent keratopathy after penetrating keratoplasty for aniridia.

Corneal lesions in aniridia include peripheral pannus and epithelial abnormalities that may advance centrally, resulting in the need for penetrating keratoplasty. Three patients with aniridia who underwent repeated corneal surgical procedures (one keratectomy and six penetrating keratoplasties) are described herein. A clinicopathological correlation was performed. In all three patients there was evidence of recurrent pannus and epitheliopathy on histopathological examination, which correlates with the clinical findings. These findings suggest that the pathophysiology of recurrent aniridia keratopathy may be related to a primary abnormality in the stem cells of the recipient corneal limbus. Aniridic pannus and epitheliopathy recur in grafts after penetrating keratoplasty and threaten the transplanted cornea. The risk of recurrent keratopathy should be considered when recommending a surgical procedure to patients with aniridia.

Adolescent↗
PubMed1995

Outcome of penetrating keratoplasty after ocular trauma in children.

OBJECTIVE: To characterize the outcome of penetrating keratoplasty in children for the visual rehabilitation of corneal injury. DESIGN: Multicenter retrospective study of the outcome of penetrating keratoplasty for ocular trauma in children. PATIENTS: All children aged 12 years and younger who underwent penetrating keratoplasty between January 1975 and May 1993 for penetrating corneal (n = 18) or corneoscleral (n = 3) trauma and nonpenetrating corneal trauma (n = 1). MAIN OUTCOME MEASURES: Graft survival and postoperative visual acuity improvement. RESULTS: Twenty-two children underwent 25 penetrating keratoplasties during the study period. Graft survival was 84% at 1 year and 70% at 2 years after surgery. Visual acuity improved in 15 (83%) of the 18 children with measurable preoperative and postoperative vision. Children with posterior segment injury before keratoplasty were less likely to maintain a clear graft (P = .04) and less likely to have improved vision postoperatively (P = .06). Children who received amblyopia treatment and appropriate optical correction postoperatively were more likely to have visual improvement than those who did not (P = .02). CONCLUSIONS: Penetrating keratoplasty for corneal trauma is generally a successful operation in the pediatric age group, with visual improvement seen in more than four fifths of cases. Graft survival and visual outcome are best in patients with trauma limited to the anterior segment. Aggressive postoperative refractive correction and amblyopia management also appear to contribute to a better visual outcome in pediatric keratoplasty.

Child↗
PubMed1995

The ocular surface as part of the mucosal immune system: conjunctival mucosa-specific lymphocytes in ocular surface pathology.

The mucosal immune system includes mucus membranes of the gut, respiratory and urogenital tracts. Mucosa-specific, intraepithelial lymphocytes (IELs), that correspond to the suppressor/cytotoxic subset and also express the human mucosal lymphocyte antigen (HML-1), are a unique component of this system. We have recently demonstrated these cells in the human conjunctiva, establishing the ocular surface as an integral part of the mucosal immune system. In this study we examined the distribution of lymphocyte subsets, with particular attention to mucosa-specific lymphocytes, in two ocular surface disorders, namely conjunctival intraepithelial neoplasia (CIN) and ocular cicatricial pemphigoid (OCP). Cryosections of biopsy specimen were immunostained using a panel of monoclonal antibodies against different lymphocyte subsets. In CIN, the CD8/HML ratio was decreased (1 +/- 0) and CD8/CD4 ratio was reversed (0.54 +/- 0.21). HML-1+ cells were distributed throughout the epithelial layers of dysplastic tissue. Biopsy specimens of OCP showed normal ratios of CD8/HML (1.4 +/- 0.16) but the CD8/CD4 was low (1.29 +/- 0.88). Association of HML-1+ cells with the basal layer of normal epithelium and with all layers of dysplastic epithelium suggests that expression of HML-1 antigen may be induced by actively dividing cells. HML-1+ cells may have a role in immune mechanisms associated with ocular surface disorders.

Adult↗
PubMed1995

Suture erosion after penetrating keratoplasty.

Because suture erosion after keratoplasty is an important risk factor for inflammation, infection, vascularization, and graft rejection, we aimed to delineate patient characteristics associated with these erosions. One hundred eyes of 97 consecutive patients who presented to our service with 10-0 nylon suture erosion after keratoplasty were selected for study. Patient age, preoperative diagnosis, duration from surgery, location and type of eroded suture, vascularity of recipient bed, contact lens or topical steroid use, and presence of infiltrate at the erosion site and subsequent culture results were tabulated. The average duration from keratoplasty to presentation was 33 (range 1-144) months. The locations of the eroded sutures were superior in 53%, nasal in 17%, temporal in 16%, and inferior in 14% of eyes (p < 0.005). Seventy-one percent of the eyes presented with broken sutures (an average 36 months postoperatively) and 29% with intact but loosened eroded sutures (an average 25 months postoperatively, p < 0.05). Sixty-nine percent of the eyes were being treated with topical steroids and presented 11 months earlier (29 months postoperatively) than did those not being treated with topical steroids (40 months postoperatively, p < 0.05). Eyes that had been subjected to keratoplasty for inflammatory conditions presented with suture erosion 10 months earlier than did those that had been subjected to keratoplasty for noninflammatory conditions (p = 0.09). Of the 10 eyes with a suture-related stromal infiltrate, one was culture-positive. Increased elapsed time from surgery, superior position of the suture, topical steroid use, and inflammatory ocular disorders are associated with suture erosions after penetrating keratoplasty.

Adolescent↗
PubMed1995

Subpectoral implantation of ICD generators: long-term follow-up.

A nonthoracotomy surgical approach using an endocardial electrode and combined implantation of a subcutaneous patch and the implantable cardioverter defibrillator (ICD) generator in a subpectoral pocket has been described. We report the long-term follow-up results in patients undergoing implantation using this approach. The patient population consisted of 28 patients (22 men and 6 women) with a mean age of 59 +/- 12 years. The underlying heart disease consisted of coronary artery disease in 20 patients and dilated cardiomyopathy in 8 patients. Sustained ventricular tachycardia was the mode of presentation in 16 patients and sudden cardiac death in 12 patients. The mean left ventricular ejection fraction was 31% +/- 6%. The lead system consisted of an 8 French bipolar passive fixation rate sensing lead positioned at the right ventricular apex, an 11 French spring coil electrode positioned at the superior vena cava-right atrial junction (surface area 700 mm2), and submuscular placement of a large patch (surface area 28 cm2) on the anterolateral chest wall near the cardiac apex via a submammary incision. A defibrillation threshold of < or = 15 joules (J) was required for implantation. This criterion was not satisfied in five patients; thus, a limited thoracotomy was performed via the submammary incision, and the large patch was placed epicardially. The mean R wave amplitude was 12 +/- 3 mV, the mean pacing threshold was 1.0 +/- 0.5 V at 0.5 msec, and the mean defibrillation threshold was 12.6 +/- 3 J. ICD generators implanted were the Ventak-P in 17, PCD-7217 in 5, and the Cadence V-100 in 6 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Defibrillators, Implantable↗
PubMed1995

Sinus node reentrant tachycardia.

This review article discusses the electrophysiological basis of sinus node reentry, clinical features of sinus node reentry, and the management of this uncommon tachycardia with drugs and ablative therapy. It also proposes the use of the term "sinoatrial reentrant tachycardia" for this form of tachycardia.

Animals↗
PubMed1995

Ventricular tachycardia during exercise testing as a predictor of sudden death in patients with chronic chagasic cardiomyopathy and ventricular arrhythmias.

OBJECTIVE: To verify the prognostic value of exercise induced ventricular arrhythmias in patients with chagasic cardiomyopathy. METHODS: 69 consecutive patients (37 male, 32 female; age range 21-67 years) with chronic chagasic cardiomyopathy and ventricular arrhythmias (more than 10 ventricular premature complexes per hour) were evaluated during treadmill exercise testing, using the Bruce protocol. Protocol end points were peak heart rate or presence of sustained ventricular tachycardia. MAIN OUTCOME MEASURE: Sudden cardiac death. RESULTS: 44 patients (group I) developed ventricular tachycardia during exercise testing (five sustained and 39 non-sustained), and 25 did not (group II). After a follow up of 24 (SD 15) months sudden cardiac death occurred in seven patients in group I and in none in group II (P < 0.05). CONCLUSIONS: Ventricular tachycardia on exercise testing is significantly associated with sudden cardiac death in patients with chronic chagasic cardiomyopathy and ventricular arrhythmias.

Adult↗
PubMed1995

Long term results of fast pathway ablation in atrioventricular nodal reentry tachycardia using a modified technique.

OBJECTIVE: To assess immediate and long term success of "fast" pathway catheter ablation with graded use of radiofrequency energy in patients with classic atrioventricular nodal reentrant tachycardia (AVNRT) and evaluate clinical, procedure related, and electrophysiological features affecting long term results. DESIGN: 31 consecutive patients with classic AVNRT at electrophysiological study, who were candidates for radiofrequency ablation. Patients were followed for an average of 24 months after ablation. SETTING: All studies and ablations were performed in an electrophysiological laboratory under fluoroscopic guidance using standard electrophysiological techniques. INTERVENTION: Radiofrequency application was performed at the site of proximal His bundle electrogram with A:V ratio of > 1. It was started at 10 W with increment of 5 W to a maximum of 25 W at 60 s. With the onset of junctional rhythm, atrial pacing was begun in order to monitor the PR interval. Application was terminated prematurely with a non-conducted P wave, continued prolongation of the PR interval beyond 50% of the baseline, or a threefold rise in impedance. RESULTS: Successful ablation was possible in 30/31 patients (97%) with an average of seven applications (range 1-10). It was associated with significant prolongation of PR interval (P < 0.001) and AV Wenckebach cycle length (P = 0.01). Ventriculo-atrial conduction was abolished in 24/30 patients (82%) with successful ablation. Two patients developed transient complete heart block (3 and 12 min) and one persistent right branch block. Four patients had late recurrence. Presence of ventriculo-atrial block was the only electrophysiological index predictive of long term success (P = 0.01). CONCLUSIONS: Graded use of radiofrequency energy and atrial pacing to monitor PR interval decreases the risk of atrioventricular block in patients undergoing fast pathway ablation for AVNRT. Ventriculo-atrial block is predictive of long term success and should be a preferred end point for fast pathway ablation.

Adolescent↗
PubMed1995

Positive donor rim culture in penetrating keratoplasty.

A 3-year retrospective study on the risk factors of positive donor rim cultures in penetrating keratoplasty was performed. One thousand and ninety-seven consecutive donor rim cultures were reviewed from the period between June 1990 and October 1993 to determine the rate of culture positivity. The sex, age, diabetes status, use of respirator at time of death, cause of death, harvesting technique, storage time, and corneal storage medium utilized for the donors with positive donor rim culture were compared to those for 100 randomly selected culture negative donor controls. Logistic analysis was performed to eliminate confounding effects. Forty-six of the 1,097 (4.19%) donor rim cultures were positive. We found an association between the in situ technique for donor harvesting and culture negativity (p = 0.03). None of the other donor characteristics was associated with culture positivity. None of the 46 recipients who received the positive culture corneas developed endophthalmitis. In situ cornea harvesting promotes less contamination than enucleation and enriched gentamicin and streptomycin storage medium may further decrease donor rim culture positivity.

Anti-Bacterial Agents↗
PubMed1994

The role of parasympathetic modulation of the reentrant arrhythmic substrate in the genesis of sustained ventricular tachycardia.

The influence of parasympathetic activity on the reentrant arrhythmic substrate in the genesis of sustained ventricular tachycardia remains unclear. To assess this influence, we studied the heart rate variability in 59 patients referred for invasive electrophysiological testing. In addition, the presence of late potentials and high grade ventricular ectopy, and the left ventricular ejection fraction was determined. The 28 patients with inducible sustained ventricular tachycardia were found to have lower heart rate variability by time- and frequency-domain measurements over 24 hours when compared to the 31 subjects who were noninducible. PNN50 was 4% in the inducible patients, whereas it was 9% in the subjects who were noninducible (P = 0.03). Similarly, HFP24H was 9 and 14 msec, respectively (P = 0.02). MAXHFP1H also differed (20 vs 27 msec [P = 0.04]) but not MINHFP1H (5 vs 6 msec). There was no association between heart rate variability and late potentials, degree of ventricular ectopy, or left ventricular ejection fraction. Thus, vagal tone does not appear to correlate with the presence of late potentials, ventricular ectopy, or left ventricular dysfunction. Low mean as well as maximal vagal tone, in contrast to minimal vagal tone, predicts inducibility of sustained ventricular tachycardia. Our data suggest that the inability to modulate parasympathetic tone appears to be an important determinant in the genesis of reentrant sustained ventricular tachycardia.

Action Potentials↗