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Biomedical subjects

M Serratto

Publications and source records attributed to M Serratto.

10 recordsLinked to original sources

Electrophysiologic studies in tricuspid atresia.

Five patients with tricuspid atresia underwent His bundle studies with the recording catheter placed close to the mitral valve ring. Right atrial pacing and measurement of the refractory periods were performed in three. The prolonged intraatrial conduction time found in all patients is thought to be caused by a hypertrophied and dilated right atrium with increased internodal distance due to stretching of internodal pathways. The A-H interval was normal in all; the H-V interval was short in three and normal in two. The pattern of left axis deviation in the group with a short H-V interval is thought to be due to early origin of the posterior branches of the left bundle branch from the bundle of His and early activation of the posteroinferior parts of the left ventricle. The pattern of left axis deviation in the group with a normal H-V interval may be related to the previously reported anomalous course of the left bundle. Atrial pacing produced a normal response. The refractory periods were within normal range, suggesting functional integrity of conduction through the atrioventricular node and bundle branches.

Adolescent

Operative repair for tricuspid atresia.

Twelve patients with tricuspid atresia underwent physiological operative repair. The criteria for their selection for operation included normal pulmonary vascular resistance and normal left atrial and left ventricular end-diastolic pressures. Four patients died (30% mortality). The 8 surviving patients developed pleural effusion, ascites, and hepatomegaly, which markedly improved in the subsequent weeks. Five of the 8 survivors underwent cardiac catheterization. The arterial oxygen saturation in these patients averaged 82% preoperatively, 89% immediately postoperatively, and 94% or better six months later. All had improved subjectively and developed increased exercise tolerance.

Adolescent

Hemodynamic evaluation of Fontan operation in tricuspid atresia.

Six patients underwent hemodynamic studies at 2 to 34 months (mean 15 months) following a modified Fontan operation. Only one patient had a valve at the inferior vena cava (IVC)-right atrium (RA) junction. Average age at surgery was 12 years (range 5-26 years). Three patients were catheterized twice. Postoperative studies showed four patients to be in sinus rhythm and two in junctional rhythm. Two patients had a RA-left pulmonary artery (LPA) gradient across the conduit of 1.5-10 mm Hg. The RA pressure was elevated an average of 17 mm Hg (10-34). All patients showed good atrial transport function regardless of their rhythm. The average arterial saturation was 92% (87%-97%), which was an improvement of 13% over preoperative values. Residual hypoxemia was due to pulmonary vein desaturation and to atrial right-to-left shunting early after surgery and to atrial right-to-left shunt alone, later. Death followed re-operation for removal of the porcine valves in the patient with two valves inserted. Macroscopically, both valves were found to have fibrous tissue ingrowth that had fixed them in a semi-open position.

Adult

Patterns of atrioventricular conduction in children.

In this study, intracardiac electrograms were performed in 20 children--ranging in age from eight months to 18 years and without evidence of conduction disturbances on the scalar electrocardiogram--to determine the normal conduction patterns, response to atrial pacing, and values of refractory periods. Atrial pacing--18 cases--induced a prolongation al AH on increasing heart rates in all; 11 developed Wenckebach block proximal to the bundle of His at the mean pacing rate of 224 per minute +/- 45 (1 S.D.). Refractory periods were shorter than in adults. Study of the pattern of A-V conduction revealed three types of response: (1) the atrium was the limiting structure in 11 cases; (2) the delay occurred in the A-V node only in four cases; and (3) the delay occurred both in the A-V node and His-Purkinje system. This response was observed in one case only.

Adolescent

Sinus node re-entry and sinus node tachycardia.

Five patients are reported with SN echoes which could be produced by the technique of APD. The RA was paced at the basic rate and the SEI was measured repeatedly. SN echoes were diagnosed on the basis of: (1) A1A3 interval shorter than the SEI; (2) upright P-waves in Leads II and III; (3) activation of high RA preceding the activation of low RA; (4) lack relation to critical delay in the A-V node or HPS; (5) definite echo zone. In one of the cases, attacks of reciprocating tachycardia through the SN occurred spontaneously and also could be initiated by an SN echo. These were terminated by a single APD or by atrial pacing.

Adolescent

Surgical bifascicular block.

Electrophysiological studies were performed in 18 patients who developed bifascicular block after repair of ventricular septal defect (VSD) or tetralogy of Fallot (TF). Two had transient complete heart block (CHB) in the immediate postoperative period. The P-A intervals were normal in all. A-H and H-V intervals were prolonged in three and four cases, respectively. Atrial pacing at progressively increasing heart rates was performed in 15 patients; two developed type II block distal to the His bundle (H). The effective and functional refractory periods (ERP and FRP) of the atrium (11 cases) were normal in all. The ERP of the A-V node (seven cases) was prolonged in found and the FRP was increased in three. The ERP of the ventricular specialized conduction system was measured in two cases and was prolonged in one. In all, seven cases had abnormalities indicating disease of the A-V node and/or His-Purkinje system. Recording of intervals, atrial pacing, and determination of refractory periods (RPs) was necessary to reveal all conduction abnormalities. One patient died of unrelated causes. The others are alive and in sinus rhythm with intact conduction 3 to 16.5 years following surgery (mean follow-up of 8.3 plus or minus 0.95 years). The clinical course in patients with normal and abnormal findings was equally benign. Prophylactic insertion of demand pacemakers does not appear indicated in these patients.

Adolescent