What is the real practice of exercise echocardiographic testing in asymptomatic patients with severe aortic stenosis? / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Although exercise testing has been suggested to help predict clinical outcome, limited data are available to guide how exercise Doppler echocardiography (ECG) can be used clinically in asymptomatic patients with aortic stenosis (AS). The aim of this study was to assess the clinical value of exercise echocardiographic testing in asymptomatic patients with severe AS.</p><p><b>METHODS</b>Symptom-limited treadmill exercise testing using the modified Bruce protocol was performed in 31 asymptomatic patients (mean age (62 ± 11) years) with severe AS (aortic valve area <1 cm(2), peak aortic velocity (AV Vmax) >4 m/sec, or a mean transaortic pressure gradient (AV mean PG) >40 mmHg (1 mmHg = 0.133 kPa)) with normal left ventricular (LV) systolic function (LV ejection fraction (EF) >50%). Clinical symptoms, vital signs, ECG, and Doppler hemodynamics were obtained during and/or immediately after exercise.</p><p><b>RESULTS</b>Aortic valve replacement (AVR) was performed in 18 patients during follow-up. The patients who had AVR exhibited higher baseline AV mean PG (51 (35-84) vs. 44 (25.2-57.0) mmHg; P = 0.031). There were no significant differences between the AVR group and non-AVR group including exercise duration (7.47 (2.32-11.59) vs. 7.25 (4.06-10.52) minutes, P = 0.917), exercise capacity (10.1 (4.6-12.8) vs. 10.1 (7.0-12.8) metabolic equivalents, P = 0.675), and an increment in AV mean PG by exercise (18.5 (3.2-48.0) vs. 12.6 (4.4-32.1) mmHg, P = 0.366). Univariate regression analysis revealed that independent determinant of AVR was the baseline AV mean PG (P = 0.031).</p><p><b>CONCLUSIONS</b>Although additional value of exercise ECG was demonstrated, baseline transaortic mean pressure gradient is the major determinant of AVR. Further large-scale prospective studies are required to determine whether surgery should be recommended in the presence of an abnormal exercise ECG in asymptomatic severe AS.</p>

Prolonged expression of senescence markers in mice exposed to gamma-irradiation

Although ionizing radiation is known to induce cellular senescence in vitro and in vivo, its long-term in vivo effects are not well defined. In this study, we examined the prolonged expression of senescence markers in mice irradiated with single or fractionated doses. C57BL/6 female mice were exposed to 5 Gy of gamma-rays in single or 5, 10, 25 fractions. At 2, 4, and 6 months after irradiation, senescence markers including mitochondrial DNA (mtDNA) common deletion, p21, and senescence-associated beta-galactosidase (SA beta-gal) were monitored in the lung, liver, and kidney. Increases of mtDNA deletion were detected in the lung, liver, and kidney of irradiated groups. p21 expression and SA beta-gal staining were also increased in the irradiated groups compared to the non-irradiated control group. Increases of senescence markers persisted up to 6 months after irradiation. Additionally, the extent of mtDNA deletion and the numbers of SA beta-gal positive cells were greater as the number of radiation fractions increased. In conclusion, our results showed that ionizing radiation, especially that delivered in fractions, can cause the persistent upregulation of senescence marker expression in vivo. This should be considered when dealing with chronic normal tissue injuries caused by radiation therapy or radiation accidents.

Experience with Intracardiac Echocardiography for Guiding Transcatheter Device Closure of Atrial Septal Defects

BACKGROUND AND OBJECTIVES: Phased-array intracardiac echocardiography (ICE) is a novel method for monitoring intracardiac procedures. We report our initial experience with ICE for guiding transcatheter device closure of atrial septal defects (ASD). SUBJECTS AND METHODS: From April 2004 to March 2005, ICE was performed in 27 consecutive patients during percutaneous device closure of ASDs. The procedural feasibility, the procedure time, the fluoroscopic time, and the complication rate were compared with 27 prior cases that had utilized transesophageal echocardiography. RESULTS: The procedure was performed successfully in all patients. The total procedure time (PT), device deployment time (DT), and fluoroscopic time (FT) were 65.7+/-22.3, 30.4+/-23.8, and 12.1+/-6.4 minutes for the study group, and 73.6+/-23.7, 29.8+/-16.1, and 11.9+/-6.0 for the control group, respectively, with no significant difference between the groups. However, PT and DT were significantly shorter in the later 14 cases of the study group compared to the 13 initial cases (52.1+/-10.9 and 13.2+/-4.2 vs. 80.3+/-22.4 and 48.8+/-22.2, p<0.01, respectively). These differences were also significant compared to the control group, suggesting that there was a learning curve for the procedure. CONCLUSION: ICE is a feasible and relatively safe method for monitoring and guiding percutaneous transcatheter closure of ASDs, but a learning period can be expected to achieve better proficiency.