Liu Zhi-hong

Heart rate-corrected QT interval and QT dispersion in patients with pulmonary hypertension

SummaryOBJECTIVE: Heart rate-corrected QT interval (QTc) and QTc dispersion (QTcd) are increased and associated with ventricular arrhythmia and an increase in sudden death in a variety of diseases. This study aimed to examine QTc and QTcd in pulmonary hypertension and assess their relationship with pulmonary arterial pressure. PATIENTS AND METHODS: A total of 201 patients who had undergone right heart catheterization for a preliminary diagnosis of pulmonary hypertension between December 2003 and July 2008 were included in the study. Resting 12-lead electrocardiogram was recorded. QT interval was measured manually and corrected using Bazetts formula. Patients were divided into groups with mild-to-moderate and severe pulmonary hypertension and a control group according to mean pulmonary arterial pressure. RESULTS: In all observed cases, mean QTc was higher in severe pulmonary hypertension than in controls (428.6 ± 32.8 ms vs. 411.1 ± 28.4 ms, P = 0.018) and QTcd was higher in mild-to-moderate (60.1 ± 17.2 ms) and severe pulmonary hypertension (63.9 ± 20.5 ms) than in controls (47.3 ± 10.6 ms) (P = 0.031; P = 0.004). In men, there was no significant difference in mean QTc and QTcd. In women, mean QTc was higher in severe pulmonary hypertension than in controls (436.1 ± 39.4 ms vs. 407.6 ± 24.8 ms, P = 0.037) and QTcd was higher in severe pulmonary hypertension (68.5 ± 20.9 ms) than in both the controls (45.1 ± 12.6 ms) and patients with mild-to-moderate pulmonary hypertension (58.6 ± 14.7ms) (P = 0.002; P = 0.003). In addition, in women with pulmonary hypertension, mean QTc and QTcd were positively correlated to mean pulmonary arterial pressure (r = 0.207, P = 0.03; r = 0.236, P = 0.012). CONCLUSIONS: In women with pulmonary hypertension, mean QTc and QTcd are positively correlated to mean pulmonary arterial pressure and are significantly increased in patients with severe pulmonary hypertension.

Percutaneous Transluminal Angioplasty and Stenting for Pulmonary Stenosis Due to Takayasu's Arteritis: Clinical Outcome and Four‐year Follow‐up

Percutaneous transluminal angioplasty and stent implantation for stenotic lesions of renal arteries and other branches of the aorta in Takayasus arteritis have been reported to show good outcomes. However, this form of therapy has been reported in few cases with pulmonary artery involvement.

e0591 Effectiveness of continuous positive airway pressure on blood pressure in patients with obstructive sleep apnoea

Background and Objective Obstructive sleep apnoea is an independent risk factor of hypertension. Several recent meta-analyses based on European and Americans have shown a reduction of blood pressure (BP) of about 2 mm Hg with continuous positive airway pressure (CPAP). This lowering of blood pressure is significant in terms of reduction in both cardiovascular and cerebrovascular risk and death. This is a randomised and controlled study to evaluate the effect of CPAP on blood pressure in Chinese cohorts with cardiovascular and cerebrovascular diseases. Methods Polysomnogram was performed to 45–75 years old patients with cardiovascular and cerebrovascular diseases in China. Forty-four middle-severe OSA patients were enrolled and baseline demographic data as well as sleep study data was recorded in these patients. The subjects were then randomly assigned to receive medical therapy either alone (22 patients) or with the addition of continuous positive airway pressure (22 patients). Daytime blood pressure, heart rate and Epworth score (ESS score) of the two groups was compared after one month follow-up. Results Twenty-one patients in the CPAP group and 22 control subjects completed the study. Compared with the control group, CPAP treatment markedly reduced the daytime diastolic blood pressure (∆−0.85±4.67 vs ∆−5.09±5.38, respectively, p=0.038), and improvement in ESS scores (∆−0.80±2.16 vs ∆−5.31±2.43, p<0.001). In contrast, there were no significant changes in systolic blood pressure (∆−0.51±5.8 vs ∆−2.82±8.09, p=0.425) and heart rate. Conclusions Compared with the control group, CPAP treatment for one month was associated with significant reduction in diastolic blood pressure and improvement in ESS score. The reduction of daytime systolic blood pressure did not reach the significant point; however, it was more than 2 mm Hg. In conclusion, CPAP treatment in OSA patients with cardiovascular and cerebrovascular diseases leads to effective reduction in daytime blood pressure, which is significant for reduction of both cardiovascular and cerebrovascular risk and death.

e0394 The relationship between obstructive sleep apnea and endothelin-1 plasma levels in patients with coronary heart disease

Objective Obstructive sleep apnea (OSA) is an independent risk factor for cardiovascular morbidity and mortality. The mechanism is unknown, but recent studies provide evidence that endothelial dysfunction might contribute. So we investigate the relationship between obstructive sleep apnea and endothelin-1 (ET-1) plasma levels in patients with coronary heart disease. Methods 287 patients with coronary heart disease were enrolled and an overnight polysomnography was performed to all of them. According to the apnea-hypopnoea index, the patients were divided into four groups: no OSA group (AHI<5, n=58), mild OSA group (5≤AHI<15, n=82), moderate OSA group (15≤AHI<30, n=70), severe OSA group (AHI≥30, n=77). Plasma levels of endothelin-1 were detected to all the patients. Results Compared with no and mild OSA group, endothelin-1 plasma levels in severe OSA group elevated significantly (p=0.009), even after analysis in a general linear model with correction for confounders. Plasma ET-1 levels showed an increasing trend within no OSA, mild OSA and moderate OSA group, however no statistically significant was observed between no OSA group and patients with mild or moderate OSA, respectively (p=0.421, p=0.226). Conclusion Among patients with coronary heart disease, plasma ET-1 levels elevated significantly in severe OSA group. This might support that severe OSA has more effects on endothelium function for coronary heart disease than mild and moderate OSA.

e0600 Impacts of obstructive sleep apnoea on the blood pressure in hypertensive patients under the optimal medication

Background and Objective Obstructive sleep apnoea (OSA) is a prevalent disease, however only 10% OSA patients receive regular treatment. OSA is an independent risk factor for hypertension and cardiovascular diseases. We aim to investigate the impacts of obstructive sleep apnoea on the blood pressure in hypertensive patients under the optimal medication though office blood pressure and 24 h ambulatory blood pressure monitoring (24 h ABPM), respectively. Methods 52 patients with hypertension were enrolled consecutively and all received the optimal medication for hypertension. An overnight polysomnography and a 24 h ABPM were performed to each patient. According to the apnoea-hypopnoea index, the patients were divided into four groups: no OSA group (AHI<5, n=13), mild OSA group (5≤AHI<15, n=19), moderate OSA group (15≤AHI<30, n=11), severe OSA group (AHI≥30, n=9). The results of 24 h ABPM and office pressure were compared respectively. Results As to the 24 h ABPM results, 24 h systolic and diastolic pressures were significantly higher in severe OSA group than no OSA group (p value is 0.036 and 0.022), and night-time systolic and diastolic pressures were significantly higher too (p value is 0.046 and 0.024) in severe OSA group. Whereas no significant differences were found when compare day-time systolic and diastolic pressures between groups. Moreover, night-time diastolic pressure was significantly higher in severe OSA group than mild OSA group (p value is 0.039). After adjusting the confounders including age, sex, BMI, smoking and drinking history, and cardiovascular diseases, the statistic differences still remained. However, Office blood pressure including systolic and diastolic blood pressure had no significant differences between each two groups. Conclusion Severe OSA significantly increases blood pressures, especially night-time blood pressures, of hypertensive patients who receive the optimal medication for hypertension. 24 h ABPM is more accurate than office pressure to evaluate the blood pressure of hypertensive patients with OSA.