[Diagnosis of total block in the bundle of His with rhythm of idioventricular substitution].
His bundle (HB) recording does not allow the recognition of third degree intrahisian block in patients with complete atrio-ventricular block (AVB) associated with idioventricular rhythm, due to the absence of pacemaker activation in the distal HB region. We have observed fixed retrograde distal HB activation in the standard HB recording of a patient with complete AVB and ventricular rhythm at a rate of 28/min. Retrograde distal HB activation (h'r) did not disappear during apical right ventricular pacing, in association with the complete absence of retrograde nodal conduction: concealed retroconduction into the proximal HB did not allow the recording of anterograde hisian deflection when the interval between h'r deflection and the subsequent sinus atriogram was shorter than 200 msec. Distal HB bipolar pacing using low energy stimulus resulted in 1:1 ventricular response and normal QRS duration in the absence of nodal retroconduction, thus proving the localization of bidirectional block within the HB. The unmasking of retrograde V-h' conduction during idioventricular rhythm was likely related to phase 4 retrograde delay in the branch ipsilateral to the site of the emergency ventricular focus and to the subsequent trans-septal activation of the other side of His-Purkinje system. Referring to arrhythmic problems after DDD pace-marker implantation the localization of complete AV blocks and retrograde conduction patterns are discussed.
Servizio di Cardiologia Ospedale S. Biagio, Domodossola, Novara.
M
M
D'Aulerio
G
G
Sauro
A
A
Totteri
L
L
Rossi
E
E
Occhetta
G
G
Folini
M
M
Tessitori
G
G
Tirella
D000368:Aged; D002036:Bundle of His / Q000503:physiopathology; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography; D006327:Heart Block / Q000175:diagnosis* / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology; D006339:Heart Rate; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008297:Male
Diagnosi di blocco totale intra-hissiano con ritmo di sostituzione idioventricolare.