RESUMEN
Background: Aortic valve replacement (AVR) may complicate conduction abnormalities and require permanent pacemaker (PPM) implantation. New techniques that lessen this challenge may lead to the development of new approaches. Our objective was to evaluate the contemporary incidence of early postoperative PPM implantation in patients undergoing isolated AVR and root disease with the standard AVR surgical technique compared with the novel suture AVR technique. Methods: The clinical data of 354 patients (250 male, 104 female) who underwent surgery for isolated AVR and root disease in different referral cardiology departments in Tabriz, Iran, over 4 years were analyzed. Patients with preoperative significant conduction abnormalities were excluded from the study. The patients were evaluated for in-hospital mortality, postoperative PPM implantation, and their stay in the ICU after surgery. Results: The mean age of the patients was 52.46±16.13 years. Totally, 183 patients (51.7%) were operated on with the new suture AVR technique. In-hospital mortality was lower in this group than in the group that underwent the "classic" surgical technique (2.5% vs 3.7%). PPM implantation was required in 3 patients (0.8%) after the novel suture AVR technique, whereas it was needed in 12 patients (3.4%) in the other group (P=0.024). The mortality rate was 9 patients (2.5%) in group 1 and 13 patients (3.7%) in group 2, which was not statistically significant (P=0.296). According to the logistic regression, the survival rate in the group operated on with the classical surgical method was 0.27 times higher than that in the patients operated on with the new method. Conclusion: Permanent complete AV block is a critical complication after AVR surgery. A lower PPM requirement and higher survival in patients operated on with the new method was the main finding of this study. New techniques with lower PPM requirements may be suitable for cardiac surgery.
RESUMEN
We present a C-band Mach-Zehnder modulator with meandered phase shifters and a compact footprint of 432 × 260 µm2 on the silicon-on-insulator platform. Electrode, p-n junction, and optical transit time are considered when performing the electro-optic bandwidth (EO BW) simulations. The simulation results prove that the dominant bandwidth limiting factor for this type of modulator is optical transit time. The insertion loss of the modulator without bias is 2.1 dB. The measured half-wave voltage (V π ) and 3-dB EO BW at -0.5 V bias are 6.4 V and 7.7 GHz, respectively. 53 Gbaud PAM-4 transmission over 2 km of standard single-mode fiber is achieved at a bit error rate (BER) below the 6.7% overhead hard-decision forward error correction BER threshold of 3.8×10 -3.
RESUMEN
We characterize the electro-optic frequency response of a four-port traveling-wave dual-drive modulator with relatively strong coupling amongst the electrodes. We show that the electro-optic frequency response of the MZM can still be predicted with the 2×2 cascaded matrix model if the MZM is symmetric and differentially driven.
RESUMEN
We present a study on electrical and optical trade-offs of the doping map in a ring modulator. Here, we investigate the effects of the high-doped region distance to edge of the waveguide sidewall. Four groups of ring modulators with different rib-to-contact distances are fabricated and measured where the key parameters such as extinction ratio, insertion loss, transmission penalty, and bandwidth are compared quantitatively. Small-signal responses for the selected ring modulators are simulated where results are in agreement with measurement results. We show that, at 4dB extinction ratio, decreasing the high-doped region distance to rib from 800nm to 350nm will increase the bandwidth by 3.8 ×. However, we observed 8.4dB increase the insertion loss. We also show that the high-doped region location affects the trade-off between bandwidth and frequency response magnitude at low frequencies. At 350nm, this trade off is 2.5 × and 3.8× more efficient compared to 550nm and 800nm, respectively.
