The seventh-generation RR (SC57), the Honda CBR1000RR, was the successor to the 2002 CBR954RR. While evolving the CBR954RR design, few parts were carried over to the CBR1000RR.[4] The compact 998 cc (60.9 cu in) in-line four was a new design, with different bore and stroke dimensions, race-inspired cassette-type six-speed gearbox, all-new ECU-controlled ram-air system, dual-stage fuel injection, and center-up exhaust with a new computer-controlled butterfly valve. The chassis was likewise all-new, including an organic-style aluminum frame composed of Gravity Die-Cast main sections and Fine Die-Cast steering head structure, inverted fork, Unit Pro-Link rear suspension, radial-mounted front brakes, and a centrally located fuel tank hidden under a faux cover. Additionally, the Honda Electronic Steering Damper (HESD) debuted as an industry first system which aimed to improve stability and help eliminate head shake while automatically adjusting for high and low speed steering effort.
Cbr 954 Valve Specs On A 2006
An all-new ninth-generation RR (SC59), the CBR1000RR was introduced at the Paris International Motorcycle Show on September 28, 2007 for the 2008 model year. The CBR1000RR was powered by an all-new 999 cc (61.0 cu in) inline-four engine with a redline of 13,000 rpm. It had titanium valves and an enlarged bore with a corresponding reduced stroke. The engine had a completely new cylinder block, head configuration, and crankcase with lighter pistons. A new ECU had two separate revised maps sending the fuel and air mixture to be squeezed tight by the 12.3:1 compression ratio. Ram air was fed to an enlarged air box through two revised front scoops located under the headlamps.
For 2017, with the 25th anniversary of the Fireblade, Honda has updated its flagship CBR with new bodywork and features such as throttle-by-wire and traction control for the first time that works with selectable ride modes. A retuned engine which now produces a claimed 189 hp (141 kW) and 153.2 hp (114.2 kW)[6] at the rear wheel, a 10 hp increase, titanium muffler and a 14 kg (33 lb) weight reduction (compared with previous ABS model) for a wet weight of 196 kg (433 lb).[6] Some of the new features on the SP model are semi-active Öhlins Electronic Control suspension (S-EC), Brembo monobloc four-piston front brake calipers, titanium fuel tank and a 13:1 compression ratio. Also adding an even more exotic limited production "SP2" variant with Marchesini forged wheels and with larger valves of which 500 units will be sold.[7][8][9]
Left ventricular remodeling, enlargement of the left ventricle, is a well-known consequence of left ventricular dysfunction [1]. Medical treatment of chronic left ventricular heart failure is thought to cause left ventricular reverse remodeling, which is a reduction in the size of the left ventricle. Not only medical treatment, but also mitral valve surgery can cause left ventricular reverse remodeling. Left ventricular reverse remodeling can lead to better clinical outcomes. In contrast, changes in the size of the left atrium have not been as well studied. Left atrial enlargement is associated with adverse cardiovascular outcomes, including left ventricular dysfunction, atrial fibrillation, and stroke [2,3]. Causes of left atrial enlargement are thought to include atrial fibrillation and mitral valve disease [4].
Patients with severe long-standing chronic mitral valve disease or atrial fibrillation can experience alterations in the size of the left atrium, a process known as left atrial remodeling [5]. For example, left atrial remodeling can be caused by pressure overload in association with mitral stenosis or volume overload in association with mitral regurgitation [4]. Left atrial remodeling includes left atrial dilatation, left atrial dysfunction, and left atrial failure [6,7]. Since mitral valve surgery can correct anti-physiological conditions in the mitral valve, it can also cause left atrial reverse remodeling.
In this study, we aimed to identify predictors of midterm left atrial reverse remodeling after mitral valve surgery, and to compare left atrial reverse remodeling and left ventricular reverse remodeling.
A total of 105 mitral valve surgeries were performed between 2006 and 2009 at our institution and were included in this study. Initial data were collected from patient medical records. Full Doppler echocardiography was performed preoperatively and more than 6 months postoperatively for all patients.
Left ventricular end-systolic diameter (LVDs), left ventricular end-diastolic diameter (LVDd), and end-diastolic septal and posterior wall thickness were measured in the parasternal view using 2D-guided M-Mode echocardiography in accordance with the recommendations for chamber quantification [8]. Left ventricular ejection fraction (EF) and mitral valve area were also recorded. Left atrial volume was measured using the prolate ellipse method [9]. The postoperative peak and mean diastolic pressure gradient across the mitral valve and tricuspid valve were calculated from the apical 4-chamber view.
All surgeries were performed under general anesthesia. Anesthetic techniques and medications were similar in all patients. Anesthesia was induced with fentanyl, propofol, and neuromuscular paralytic drugs and was maintained by inhalation anesthesia using the same drugs. All mitral valve surgeries were performed with moderate hypothermia and antegrade cold cardioplegic solution. Bypass management included membrane oxygenators, arterial line filters, use of a roller pump, a nonpulsatile flow of 2.4 l/min/m2 and a target mean arterial pressure > 50 mm Hg. MAZE procedures were performed using a radiofrequency ablation device.
Overall, left atrial volume decreased from 108.6 72.6 mL (preoperative period) to 79.4 53.8 mL (long-term follow-up). Mid-term left atrial volume was decreased by >30% from baseline in 43 patients (group A), but no such changes were observed in 62 patients (group B). The average follow-up was 18.0 11.1 months, and the average duration between surgery and follow-up echocardiogramphy was 16.2 1.33 months. Tables 1 and 2 show preoperative and perioperative variables, respectively. Patients in group A were younger (64.1 7.4 years) than those in group B (69.3 7.7 years; p = 0.0029). The proportion of males was also higher in group A (67.4%) compared with group B (46.7%), and the prosthesis was larger in group A (27.8 1.7 mm) than group B (26.7 1.7 mm) (p = 0.005). The proportion of patients with a pathological disorder, mainly mitral regurgitation, did not differ between the groups (A, 88.4% vs. B, 82.3%; p = 0.42), nor did the proportion requiring valve repair (A, 11.6% vs. B, 8.1%; p = 0.73). A mechanical valve was used in 65.8% of patients in group A and 31.6% of patients in group B (p = 0.005). There was no betweengroup difference in the prevalence of preoperative atrial fibrillation (A, 48.8% vs. B, 48.4%; p = 0.99), performance of MAZE procedures (A, 25.6% vs. B, 16.1%; p = 0.32), or late atrial fibrillation (A, 32.6% vs. B, 33.0%). Table 3 shows the results of a multivariate predictor analysis of mid-term left atrial reverse remodeling. Factors with p
model (OR = 0.93, 95% CI 0.88 - 0.99; p = 0.03). Preoperative and follow-up echocardiographic data are shown in Table 4. Patients in group A had a lower pressure gradient across the prosthetic valve (peak A, 8.0 4.4 vs. B, 10.3 4.2, p = 0.01; mean A, 3.0 1.3 vs. B, 3.9 1.9, p = 0.01). Preoperative echocardiography data showed that the preoperative LVDd was larger (A, 55.9 8.6 mm vs. B, 51.3 9.5 mm; p = 0.02), the preoperative transpulmonary gradient was higher (A, 36.8 16.6 mm Hg vs. B, 31.0 11.3 mm Hg; p = 0.04), and the preoperative left atrial volume was larger (A, 129.0 87.1 mm vs. B, 94.5 57.2 mm; p = 0.02) among patients in group A compared with those in group B. Mid-term echocardiography showed that the peak (A, 8.1 4.1 mm Hg vs. B, 10.3 4.2 mm Hg; p = 0.01) and mean (A, 2.9 1.2 mm Hg vs. B, 3.9 1.8 mm Hg; p = 0.01) trans-mitral pressure gradient was lower among patients in group A compared with those in group B. The changes in LVDd and LVDs (mid-term/preoperative %) were different between the groups (Dd A, 85 8% vs. B, 94 12%, p = 0.0007; Ds: A, 90 17% vs. B, 98 19%, p = 0.04). There was a weak correlation between the changes in Dd and left atrial volume (correlation coefficient 0.27, 95% CI 0.07 - 0.45; p = 0.008) (Figure 1). Clinical outcomes are shown in Table 5. The survival rate and freedom from MACE were not significantly different between the groups (p = 0.31 and p = 0.87 by log-rank test) (Figures 2 and 3).
disease [4]. Atrial enlargement has also been considered to occur as a consequence of atrial fibrillation [5]. While left ventricular reverse remodeling after mitral valve surgery has been widely reported, left atrial remodeling has not been well studied [1].
Left atrial volume rather than left atrial dimension or size has traditionally been considered important [6,10- 14]. Recently, left atrial volume and function have been reported to be important for atrial fibrillation and left ventricular dysfunction [6,13,15-17]. Left atrial enlargement is common and is associated with various adverse cardiovascular outcomes, including atrial fibrillation and thromboembolic events [13,18]. Osnranek et al. reported that patients with a left atrial volume > 32 mL/m2 had an almost 5-fold increased risk of postoperative atrial fibrillation after cardiac surgery [18]. Left atrial volume is a more robust marker of cardiovascular events than either left atrial area or diameter [15]. Left atrial enlargement can also be induced by acceleration of mitral valve pathology, a process known as left atrial remodeling. Left atrial remodeling leads to left atrial enlargement, left atrial dysfunction, and left atrial failure [6,7]. Recently, left atrial remodeling has also been associated with left ventricular diastolic dysfunction [19-21]. This process is commonly associated with pressure overload in mitral stenosis or volume overload in mitral regurgitation. 2ff7e9595c
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