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No abstract

Wave intensity (WI) is a new hemodynamic index, which is defined as (dP/dt)(dU/dt) at any site of the circulation, where dP/dt and dU/dt are the time derivatives of blood pressure and velocity, respectively. Arterial WI in normal subjects has two positive sharp peaks. The first peak occurs during early systole when a forward-traveling compression wave is generated by the left ventricle. The magnitude of this peak increases markedly with an increase in cardiac contractility. The second peak, which occurs towards the end of systole, is caused by generation of a forward-traveling expansion wave by the ability of the left ventricle to actively stop aortic blood flow. The interval between the R wave of the ECG and the first peak of WI (R-1st peak interval) and the interval between the first and second peaks (1st-2nd interval) are approximately equal to the preejection period and left ventricular ejection time, respectively. Using a combined Doppler and echo-tracking system, we obtained carotid arterial WI noninvasively. We examined the characteristics of WI in 11 patients with mitral regurgitation (MR) before and after surgery, and 24 normal volunteers. In the MR group before surgery, the second peak was decreased and the (1st-2nd interval)/(R-R interval) ratio was reduced, compared with the normal group (140 +/- 130 vs 750 +/- 290mmHg m/s3. P < 0.0083; 20.7% +/- 3.4% vs 26.7% +/- 2.8%, P < 0.083). There were no significant differences in the first peak between the normal group and the MR group before and after surgery. The second peak in the MR group was increased significantly (P < 0.016 vs before surgery) to 1,150 +/- 830mmHg m/s3 in the early period after surgery (stage I), and to 1,090 +/- 580mmHgm/s3 in the late period after surgery (stage II). These values did not differ significantly from that of the normal group. At stage I, the (R-1st peak interval)/ (R-R interval) ratio was increased from 13.4% +/- 2.7% to 20.6% +/- 5.6% (P < 0.016 vs before surgery). At stage II, this ratio decreased to 16.2% +/- 2.8% (P < 0.016 vs stage I). but was still significantly higher than that before surgery. The (1st-2nd interval)/(R-R interval) ratio increased significantly after surgery (P < 0.016 vs before surgery) to values (27.0% +/- 4.5% at stage I and 28.9% +/- 2.6% at stage II) which did not differ significantly from that of the normal group. The recovery of the second peak after surgery suggests that the left ventricle had recovered the ability to actively stop aortic blood flow. Wave intensity is useful for analyzing changes in the working condition of the heart.

The aim of this study was to identify risk factors for acute surgical-site infection (SSI) after total joint arthroplasty in rheumatoid arthritis (RA) patients treated with nonbiologic and biologic disease-modifying antirheumatic drugs (DMARDs). We performed a retrospective study of all consecutive total hip (THA) and total knee (TKA) arthroplasties performed during a 5-year period (THA 81; TKA 339). Multivariate logistic regression analysis was performed to identify SSI risk factors. Of the patients undergoing THA or TKA, 24 cases (5.7%) developed a superficial incisional SSI requiring the use of antibiotics and three cases (0.7%) developed an organ/space SSI necessitating surgical treatment to remove the artificial joint prosthesis. Multivariate logistic regression analysis revealed that the use of biologic DMARDs [P = 0.0007, odds ratio (OR) = 5.69; 95% confidence interval (CI) 2.07-15.61] and longer RA duration (P = 0.0003, OR = 1.09; 95% CI 1.04-1.14) were the only significant risk factors for acute SSI. Furthermore, an analysis that individually evaluated major agents (n > 10) adjusted for disease duration indicated that tumor necrosis factor alpha blockers increased the risk of SSI (infliximab P = 0.001, OR = 9.80, 95% CI 2.41-39.82; etanercept P = 0.0003, OR = 9.16, 95% CI 2.77-30.25). We found that the use of infliximab or etanercept and longer disease duration were associated with an increased risk of acute SSI in RA patients. Prospective studies are thus needed to determine the safety of biologic DMARDs in the perioperative period.