AIMS: Trans-valvular impedance (TVI) recording has been proposed for the assessment of cardiac haemodynamics, assuming an inverse relationship between TVI and ventricular volume. We checked whether the TVI sensor can drive the rate-responsive function of a cardiac pacemaker following changes in the inotropic regulation of the heart. METHODS: An external DDD-R pacemaker (Ext Sophos by Medico, Padova, Italy) equipped with the TVI detecting system was tested in 30 patients on the implantation of conventional pacing leads for dual-chamber pacing. Pacing rate regulation was based on the relationship between the stroke volume and the end-diastolic volume, inferred from TVI data. After sensor calibration in basal conditions, beta-adrenergic stimulation was induced by i.v. administration of 2 microg/ml/min isoprenaline (isoproterenol) (IPN). The actual cardiac rate, the TVI waveform, the end-diastolic and systolic TVI in each cardiac cycle and the TVI-indicated rate were stored in memory as a function of time and down-loaded at the end of the session. RESULTS: All patients with intrinsic atrial activity (28/30) showed a positive chronotropic response to IPN, coupled with a significant increase in end-diastolic TVI and a four-times larger increase in end-systolic TVI. The TVI inotropic index mirrored the sinus rate time-course, with a linear correlation between the two parameters (r(2)>0.7 in 25/28 cases). As a result, the TVI-indicated rate closely reproduced the sinus rate. CONCLUSIONS: The study confirms the reliability of the haemodynamic information derived from TVI and supports its application in the regulation of rate-responsive pacing.
AIMS: Trans-valvular impedance (TVI) recording has been proposed for the assessment of cardiac haemodynamics, assuming an inverse relationship between TVI and ventricular volume. We checked whether the TVI sensor can drive the rate-responsive function of a cardiac pacemaker following changes in the inotropic regulation of the heart. METHODS: An external DDD-R pacemaker (Ext Sophos by Medico, Padova, Italy) equipped with the TVI detecting system was tested in 30 patients on the implantation of conventional pacing leads for dual-chamber pacing. Pacing rate regulation was based on the relationship between the stroke volume and the end-diastolic volume, inferred from TVI data. After sensor calibration in basal conditions, beta-adrenergic stimulation was induced by i.v. administration of 2 microg/ml/min isoprenaline (isoproterenol) (IPN). The actual cardiac rate, the TVI waveform, the end-diastolic and systolic TVI in each cardiac cycle and the TVI-indicated rate were stored in memory as a function of time and down-loaded at the end of the session. RESULTS: All patients with intrinsic atrial activity (28/30) showed a positive chronotropic response to IPN, coupled with a significant increase in end-diastolic TVI and a four-times larger increase in end-systolic TVI. The TVI inotropic index mirrored the sinus rate time-course, with a linear correlation between the two parameters (r(2)>0.7 in 25/28 cases). As a result, the TVI-indicated rate closely reproduced the sinus rate. CONCLUSIONS: The study confirms the reliability of the haemodynamic information derived from TVI and supports its application in the regulation of rate-responsive pacing.
Authors: Valeria Calvi; Giovanni Pizzimenti; Marco Lisi; Giuseppe Doria; Ludovico Vasquez; Francesco Lisi; Salvatore Felis; Donatella Tempio; Alfredo Virgilio; Alberto Barbetta; Franco Di Gregorio Journal: Adv Med Date: 2014-08-04
Authors: Vincenzo Lionetti; Simone Lorenzo Romano; Giacomo Bianchi; Fabio Bernini; Anar Dushpanova; Giuseppe Mascia; Martina Nesti; Franco Di Gregorio; Alberto Barbetta; Luigi Padeletti Journal: PLoS One Date: 2013-11-19 Impact factor: 3.240