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Biomedical subjects

S Scarfo'

Publications and source records attributed to S Scarfo'.

4 recordsLinked to original sources
PubMed1986

Intrinsic electrophysiologic properties of reentrant supraventricular tachycardia involving bypass tracts.

This study evaluates the effects of autonomic blockade (propranolol, 0.2 mg/kg, and atropine, 0.04 mg/kg) in 20 patients with paroxysmal supraventricular tachycardia (SVT). In 8 patients the SVT circuit involved a concealed atrioventricular bypass for retrograde conduction (group I) and in 12 a concealed atrio-His pathway (group II). Autonomic blockade did not significantly change atrial and ventricular refractory periods, whereas it prolonged atrioventricular nodal refractoriness without varying AH interval. The ventriculoatrial interval did not change in any patient. The H2A2 interval was unchanged in all but 2 group II patients. In both groups, the effective refractory period of the concealed bypass was prolonged by autonomic blockade. In the basal state, SVT was induced in all patients; after autonomic blockade, SVT was induced in 7 patients in group I (87%) and in 7 in group II (58%) (p less than 0.05). Cycle length of SVT was prolonged after autonomic blockade in 11 of these 14 patients. The variations were observed only in the anterograde conduction (Ae-H interval), whereas retrograde conduction (H-Ae interval) was unchanged in all patients. These data indicate that the autonomic system appears to facilitate induction of SVT in patients with concealed atrio-His bypass as well as shorten the cycle length of SVT in both groups of patients.

Adult↗
PubMed1984

Latent abnormalities of sinus node function in patients with organic heart disease and normal sinus node on clinical basis.

Sinus node (SN) function was analyzed in 22 patients (mean age: 46.2 +/- 12.9 years) with organic heart disease and normal SN on clinical basis (group I) and in 20 normal subjects (mean age: 43.9 +/- 15.6 years), (control group). Sinus cycle length (SCL), corrected sinus node recovery time (CSRT) and sinoatrial conduction time (SACT) were analyzed. After the control study, autonomic blockade (AB) was induced by i.v. propranolol (0.2 mg/Kg) and atropine (0.04 mg/Kg). Measurements of SCL, CSRT and SACT were then repeated. The mean SCL values were very similar in the two groups during the control state and after AB. There were no significant differences in SACTs between the two groups during the control state or after AB. On the contrary, the CSRT of group I was significantly longer than that of control group during the control state (344.8 +/- 78.9 versus 262.2 +/- 46.3 msec, P less than 0.001) and after AB (238.9 +/- 72.8 versus 166.8 +/- 39.3 msec, P less than 0.001). The analysis of real depression of SN automaticity (CSRT minus SACT) in the two groups shows that prolongation of CSRT in group I during the control study and after AB is related to an intrinsic abnormality of SN automaticity; on the contrary, no dysfunctions of the autonomic nervous system appear. These data indicate that the intrinsic abnormality of SN automaticity represents the earliest involvement of the SN in subjects with organic heart disease and normal SN on clinical basis, although this conclusion is speculative and requires experimental verification.

Adolescent↗