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Purpose: The aim is to measure and analyze the wave amplitudes and time intervals of differential graphs of reconstructed impedance cardiography (RICG). Methods: 180 adults with normal cardiac function between the ages of 18–78 were included in the study. Six mingled impedance changes on chest surface were simultaneously detected for each subject. The differential graphs of five impedance change components of RICG were obtained through waveform separation and software differentiation. The amplitudes of C, X, O, b waves and time intervals of Q‐b and Q‐C were measured and statistically analyzed. Results: The amplitudes of C and X waves in PL, PR, AO, and that of C, O, b waves in LV and RV, all decrease as age increases. Wave amplitudes of the female group were bigger than those of the male group (p <.01), while the Q‐C intervals of the female group were shorter than that of the male group (p <.01). Among five impedance change components, the wave amplitude of AO was larger than those of PL and PR (p <.01), and wave amplitudes of PL and PR were bigger than those of LV and RV (p <.01). Q‐C intervals of LV and RV were longer than those of AO, PL and PR (p <.01), while the Q‐b intervals of LV and RV were shorter than the Q‐C intervals of AO, PL, and PR. Conclusions: The differential graphs of RICG could reflect indirectly the physiological activities and pathological changes of the heart and of the large blood vessels in thorax. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the present study is to separate the impedance change components of the blood vessels and ventricles in thorax from the mixed impedance signals detected on the chest surface., Methods: The mixed impedance signals on the chest surface are measured with a 15 electrode lead system. The thoracic impedance equations are established and solved iteratively with the algebraic reconstructed technique. Experiments were performed on 80 healthy, otherwise normal, adults., Results: Five impedance change components for the aorta (AO), blood vessel in left lung (PL), blood vessel in right lung (PR), left ventricle (LV), and right ventricle (RV) are separated from the mixed impedance signals. The experiments show that the main waveform of the ventricular components LV and RV is contrary to that of the vascular components AO, PL, and PR, and the negative peak point of the waveform graphs of LV and RV are in phase with the second cardiac sound (S2). The waveform graphs of various components correspond with the physiological activities of the heart and blood vessels in a cardiac cycle. The statistical results for 80 normal adults show that the amplitude of AO is the largest and that of PL and PR is the next, while that of LV and RV is the smallest. There are significant differences between them (P < 0.01)., Conclusions: The mathematical model and the measurement method for the separation in the present paper are feasible.

Objective: To explore therapeutic results of local microwave ablation for hepatic metastasis and the factors influencing the survival after percutaneous microwave ablation therapy., Methods: From July 1995 to June 2005 128 patients with 282 hepatic metastases nodules with the primary diseases of upper gastrointestinal tumor (n = 26), colorectal tumor (n = 44), breast carcinoma (n = 19), pulmonary carcinoma (n = 15), and malignant tumor in other part of the body (n = 24), underwent percutaneous microwave ablation therapy and were followed up for 29.7 +/- 19.9 months (1 - 103 months). The largest diameter of the metastatic nodules was 3.5 +/- 1.6 cm (0.7 - 8.6 cm). Sixty-four cases had 140 nodules 3.0 cm in diameter. Forty-seven patients had single nodule, 44 patients had 2 nodules, and 93 patients had 3 or more nodules. Fifty-seven patients had tumor of low differentiation, 53 had tumor of middle differentiation, and 18 had highly differentiated tumors. Kaplan-Meier method was used to calculate the cumulative survival rate. Statistical comparison of the effects of potential predictive factors on survival rate was performed using log-rank analysis. Multivariate analysis of the survival rates was performed by using Cox's proportional hazard model., Results: The 1, 2, 3, 4, and 5-year cumulative survival rates of all 128 patients were 90.88%, 73.84%, 51.09%, 36.14%, and 31.89% respectively. Univariate analysis showed that tumor size (P = 0.028), tumor differentiation (P = 0.026) and local recurrence or new metastases (P < 0.001) significantly affected the survival. Multivariate analysis revealed that tumor size (P = 0.035), recurrence or new metastases (P = 0.001) and tumor differentiation (P = 0.038) each had a significant effect on survival., Conclusion: There is a significantly higher probability of long-term survival for patients with well-differentiated tumors 3.0 cm or less in diameter and without recurrence or new metastasis after percutaneous microwave ablation.

Objective: To analyze the therapeutic results and prognostic factors of hepatic metastases treated by ultrasound-guided percutaneous microwave coagulation., Methods: Seventy-four patients with 149 nodules of hepatic metastases were given percutaneous microwave coagulation therapy. The longest diameter of the metastatic nodule ranged from 0.7 - 6.8 cm (mean, 3.1 +/- 1.8 cm). The cumulative survival rate was analyzed by Kaplan-Meier method and the difference between groups was compared with log-rank test. Cox proportional hazard model was used to determine potential prognostic variables., Results: The follow-up period for the 74 patients was 5 - 83 months (mean, 25.1 +/- 11.4 months). The overall 1-, 3-, and 5-year cumulative survival rates were 91.4%, 46.4% and 29.0%, respectively. The log-rank test showed that number of metastases, tumor size, tumor cell differentiation and local recurrence or new metastases were statistically significant prognostic factors; while age, sex and site of primary tumors were not significant prognostic factors. Multivariate analysis revealed that tumor differentiation, number of metastases and recurrence or new metastases were statistically significant prognostic factors., Conclusion: Ultrasound-guided percutaneous microwave coagulation therapy for hepatic metastases in patients with single metastasis, well-differentiated tumor, and without recurrence and new metastases could achieve long-term survival.