SciELO - Scientific Electronic Library Online

 
vol.21 issue3Proportion among the segments of the normal tricuspid valve annulus: parameter for valve annuloplastyEnd stage cardiomyopathy and secondary mitral insufficiency: surgical alternative with prostesis implant and left ventricular remodelling author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Revista Brasileira de Cirurgia Cardiovascular

Print version ISSN 0102-7638

Abstract

ASSAD, Renato Samy et al. Experimental assessment of a new electrode for fetal pacing. Rev Bras Cir Cardiovasc [online]. 2006, vol.21, n.3, pp. 272-282. ISSN 0102-7638.  http://dx.doi.org/10.1590/S0102-76382006000300006.

OBJECTIVE: The prognosis of congenital complete heart block (CHB) is very poor when manifested with fetal hydrops. Fetal pacing may improve the survival rate. This study aims to assess the electrophysiological characteristics of a new lead, as well as fetal hemodynamic and metabolism under different fetal heart rates. METHODS: The new lead (T-shaped) was deployed into the myocardium of five fetal goats. Fetal cardiac output was measured by a flow transducer. CHB was achieved by cryosurgical ablation of fetal AV node. Electrophysiological parameters, hemodynamic and metabolic behavior of the fetus under different fetal heart rates were evaluated. RESULTS: The acute stimulation thresholds were consistently low. The voltage strength-duration curve remained relatively constant at pulse widths > 0.5 msec. The stimulation resistance was 1050.4 ± 76.6 ohms, and the sensed fetal R wave was 8.6 ± 5.6 mV. Fetal heart rate bellow 60 bpm was associated to low cardiac output and low blood pressure (p<0.05). Fetal bradycardia also determined oxygen saturation drop parallel to low cardiac output, with severe hypoxia below 60 bpm. CONCLUSION: The new lead allows for a less invasive procedure and stable fixation to the myocardium that may prevent lead dislodgement after fetal recovery. It seems to be compatible with safe chronic stimulation. This study suggests that a gradual increase in the fetal rate beginning on 80 bpm after implantation would be more adaptive and adequately augment fetal cardiac output.

Keywords : Fetal heart [surgery]; Heart block [congenital]; Heart block [surgery]; Hydrops fetalis; Pacemaker [artificial].

        · abstract in Portuguese     · text in English | Portuguese     · pdf in English | Portuguese