Acesso aberto Revisado por pares

What is the Diagnosis?

Qual o Diagnóstico?

Jose Mario Baggio1; Joubert Ariel Pereira Mosquera1; Ewandro Luiz Rey Moura1; Luis Gustavo Ferreira Gomes1; Wagner Luis Gali1; Alvaro Valentim Lima Sarabanda1


Citation: Junior JMB, Mosquera JAP, Moura ELR, Gomes LGF, Gali WL, Sarabanda AVL. What is the Diagnosis?. JBAC 32(2):127. doi:10.24207/jca.v32i2.990_PT


Patient OG, 62 years, with arrhythmogenic cardiomyopathy in the right ventricle and low-tolerated sustained tachycardia, user of an implantable ventricular single-chamber cardiovascular defibrillator (ICD), returned asymptomatic for routine evaluation. There was no registry of sustained arrhythmia, and the limits of stimulation and sensitivity were checked and were appropriate (Fig. 1). However, facing the device's telemetry, it was detected lack of sensitivity in a ventricular extra-systole (Fig. 2).

This way, facing the possibility that this flaw could generate failure of detection of a slow ventricular tachycardia (Fig. 3), the level of sensitivity regarding ICD was improved, with the correction of the failure in the extra-systole intermittent sensitivity.



The ICDs, differently from pacemakers that posse fixed programming, present a sensitivity gain, called SenseAbilityT (Fig. 4) in the Abbott generators, whose purpose is to avoid failure of the sensitivity of quick and low amplitude ventricular events. The beginning of this sensitivity curve improves, called decay delay (Fig. 5) in the Abbott generators, and the speed of the sensitivity improvement, called threshold start (Fig. 6) in the Abbott generators, have a goal to avoid excessive sensitivity in T-waves, which would promote an inappropriate detection of a fake ventricular tachycardia. However, specifically, in this case, the programmed sensitivity improvement was promoting a failure of the ventricular sensitivity, which was corrected with the modification in the threshold start to 50% and the decay delay to 0 ms (Fig. 7).



The programming of ICDs sensitivity is fundamental, since, if one ventricular arrhythmia is not detected, it will not be treated. Whenever the parameters of an ICD are modified to promote higher sensitivity, it must be evaluated the possibility of excessive sensitivity of T-wave or non-cardiac events (such as miopotential of the diaphragm muscle in integrated bipolar electrodes, cross-sensitivity of P-waves). Whenever the parameters of the ICD are modified to promote less sensitivity, it must be evaluated the possibility of induction of clinical arrhythmia of the patient, in order to verify if there is appropriate detection of the event.



Ellenbogen KA, Wilko? BL, Kay GN, Lau CP, Auricchio A. Clinical cardiac pacing de?brillation, and resynchronization therapy. 5a ed. Philadelphia: Elsevier; 2017. Link DOI
Barold SS, Stroobandt X, Sinnaeve AF. Cardiac pacemakers step by step. Chichester: Wiley-Blackwell; 2004.

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