BIO-RSA vs. metal-augmented baseplate in shoulder osteoarthritis with multiplanar glenoid deformity: a comparative study of radiographic findings and patient outcomes.

BACKGROUND: Reverse shoulder arthroplasty (RSA) requiring extensive reaming to address severe glenoid bone loss increases the risk of glenoid medialization and baseplate failure. We hypothesized that (1) metal-augmented baseplate prevents the medialization of the joint line and preserves glenoid bone stock similarly to bony increased-offset (BIO)-RSA and (2) bone graft viability and healing in BIO-RSA patients become compromised over time. MATERIALS AND METHODS: Eighty-one patients (83 shoulders) underwent glenoid lateralization with bone (BIO-RSA group, 44) or metal-augmented baseplate (metallic increased-offset [MIO]-RSA group, 39) and a minimum follow-up of 24 months were included. The orientation and direction of glenoid erosion was identified and recorded using computerized 3D planning. Active range of motion, and the Western Ontario Osteoarthritis of the Shoulder (WOOS) index were assessed before arthroplasty and at the last follow-up visits. Radiographic changes around the glenoid and humeral components were assessed. Healing and thickness of bone graft were evaluated by predefined criteria. Postoperative global glenoid inclination (ß angle) and retroversion were also measured. RESULTS: Delta scores of active anterior elevation were higher in the MIO-RSA group (P = .027). The differences in the other planes of shoulder motion and in WOOS index scores between the groups were not significant. Preoperative glenoid retroversion was higher in BIO-RSA patients, and glenoid inclination was similar in both groups. Type B2 and B3 glenoids had a posterior-central (91%) and posterior-superior (90%) erosion with a mean posterior humeral head subluxation of 76% and 78%, respectively. The direction of erosion in type E2 and E3 glenoids was posterior-superior, with a mean posterior humeral head subluxation of 74%. The rate of high position of the glenosphere was higher in the BIO-RSA group (P = .022), whereas the values of ß angle and postoperative retroversion were similar in the 2 groups. BIO-RSA group showed radiolucent lines <2 mm around the bone graft in 16 patients (36.4%) and decreased thickness in 15 (34.1%). Incomplete baseplate seating was found in 4 MIO-RSA patients (10%). We found higher rates of humerus condensation lines in MIO-RSA patients (P = .01) and higher rates of cortical thinning and tuberosity resorption in the BIO-RSA group (P = .027 and P = .004, respectively). CONCLUSION: Metal-augmented glenoid is a suitable alternative to BIO-RSA to preserve bone and prevent the medialization of the joint line in arthritic glenoid with multiplanar glenoid deformity. Bone and metal augmentation provided satisfactory clinical outcomes. Bone graft resorption in BIO-RSA patients raise concern about the risk of baseplate loosening and requires further long-term studies.

Pediatric elbow arthroscopy: clinical outcomes and complications after long-term follow-up.

BACKGROUND: Elbow arthroscopy is becoming increasingly important for the treatment of a wide range of acute and chronic elbow pathologies. Even if elbow arthroscopy is technically demanding, in the pediatric population this minimally invasive technique is preferred by many surgeons for the treatment of pathologies such as osteochondritis dissecans (OCD), posttraumatic stiffness (PTS), or elbow posterior impingement (PI). The aim of this study is to evaluate outcomes and safety of elbow arthroscopy in the pediatric and adolescent population after long-term follow-up. MATERIALS AND METHODS: In this retrospective study, 26 patients younger than 18 years old undergoing elbow arthroscopy were evaluated. All surgeries were performed by a single senior surgeon. Patients were divided into three subgroups based on preoperative diagnosis: OCD, PTS, and PI. After at least 60 months follow-up, several outcome measures, including range of motion (ROM), Mayo Elbow Performance Score (MEPS), and visual analog scale (VAS) were evaluated in relation to preoperative values. The level of patient satisfaction on a five-level Likert scale, any limitation or change in sport activity, and the onset of any possible complications were also evaluated. RESULTS: In the study population, we found an improvement in ROM (flexion of 14.4 ± 13.6°, extension of 19.5 ± 13.9°, pronation of 5.8 ± 5.7°, and supination of 8.5 ± 11.6°) and in validated outcome measures (MEPS of 21.0 ± 13.5 points and VAS of 3.8 ± 2.2 points). The satisfaction rate was 4.5, with no dissatisfaction. Eighty-seven percent of patients fully recovered their performance levels, 9% changed sport, and 4% were unable to return to sport. We identified one major and one minor complication, with an overall complication rate of 7.7%. No neurovascular injuries were detected. CONCLUSIONS: Elbow arthroscopy in a pediatric population can be considered an effective and safe procedure for selected pathologies when performed by an experienced surgeon. At long-term follow-up, we reported excellent clinical outcomes (both objective and subjective), with a relatively low complication rate without permanent injuries. LEVEL OF EVIDENCE: Level IV-case series.

Preoperative Osteoarthritic Grade Affects Forgotten Joint Status and Patient Acceptable Symptom State After Robotic Arm-Assisted Unicompartmental Knee Arthroplasty.

BACKGROUND: This retrospective observational study was designed to investigate the association between radiographic Ahlbäck osteoarthritis (OA) grade and postoperative joint perception in a cohort of patients undergoing medial robotic arm-assisted unicompartmental knee arthroplasty (RA-UKA), using the Forgotten Joint Status and Patient Acceptable Symptom State (PASS) as outcomes. METHODS: Between January 2014 and May 2019, 660 patients (719 knees) underwent medial RA-UKA at 2 centers. Ahlbäck OA grade was measured on preoperative knee radiographs. Postoperatively, patients were administered the Forgotten Joint Score-12 (FJS-12) and 5-level Likert scale to assess patients' satisfaction. Correlations were described among FJS-12, satisfaction, and Ahlbäck OA grade by means of logistic regression models. RESULTS: A total of 547 patients (602 knees) were assessed at a mean follow-up of 3.5 years (standard deviation 1.4). A total of 293 cases were graded as Ahlbäck 1 (Group A) and 309 knees were graded as Ahlbäck>1 (Group B). Statistically significant difference was detected in mean FJS-12 (P < .001), but not in the postoperative satisfaction level (P = .06) between the 2 groups. Patients in Group B had a significantly higher probability of attaining a "forgotten knee" after the operation, compared to Group A (P < .05). Cases in Group A had a significantly lower probability of achieving the PASS (P < .01). CONCLUSION: Patients with higher grades of OA (Ahlbäck>1) were more likely to attain a "forgotten knee," while patients with less severe OA (Ahlbäck 1) were less likely to achieve the PASS after RA-UKA. Although patients with less severe OA reported fairly good outcome, cases in which the results will be poorer are currently difficult to predict.

Heart valve surgery in a very high-risk population: a preliminary experience in awake patients.

BACKGROUND AND AIM OF THE STUDY: Heart valve surgery in high-risk patients is associated with considerable morbidity and mortality. Epidural anesthesia without mechanical ventilation has been proposed to reduce invasiveness. An analysis was conducted in very high-risk heart valve patients of mid-term survival free from complications, and patient satisfaction of regional anesthesia use, without mechanical ventilation. METHODS: A prospective follow up study was conducted in 50 patients (24 females, 26 males; mean age 74 +/- 10 years; range: 43-89 years) who underwent heart valve surgery with epidural anesthesia without endotracheal intubation. Preoperatively, all patients were in NYHA class III or IV; eight patients (16%) had undergone a previous cardiac procedure. The median Additive and Logistic EuroSCORE were 14.5 and 52%, respectively. Twenty-seven patients underwent aortic valve replacement, 10 mitral valve replacement, 10 mitral valve repair, two double valve replacement, and one patient ascending aorta replacement. Associated surgical procedures included coronary artery bypass grafting in 12 patients (24%), ascending aorta replacement in three (6%), and left ventricle reshaping in two (4%). Radiofrequency ablation to treat chronic atrial fibrillation (AF) was performed in 15 patients (30%). All patients were prospectively followed up, and a six-month quality of life assessment was performed in all survivors. RESULTS: Procedures were performed without mechanical ventilation in completely awake and conscious patients. There were two in-hospital and two long-term deaths (8%). Three patients had had previous cardiac surgery (two double valve replacements, two complex mitral valve surgery). Among survivors, 34 (71%) had an uneventful postoperative outcome, except for AF in nine cases. Eight patients required revision for bleeding; two of these were redo cases. The most consistent postoperative complication was acute renal failure in 16 patients, five of whom had previous chronic renal failure. Three patients required mechanical ventilatory support, and none had a cerebrovascular accident. Patients were discharged home after a mean of 10 +/- 5 days (including ICU stay; median 9 h). At follow up, all patients were in NYHA class I/II, and all survivors expressed their satisfaction with epidural anesthesia. CONCLUSION: Heart valve surgery while on cardiopulmonary bypass is feasible and safe using epidural anesthesia. By maintaining autonomic ventilation, a low mid-term morbidity and mortality was observed in patients in whom there was an unacceptable operative risk.

Massive mitral and pulmonary valve incompetence in a patient with left ventricular, non-compacted myocardium.

The case is reported of a patient who underwent cardiac surgery for pulmonary valve stenosis as a child, and presented as an adult with signs and symptoms of severe congestive heart failure. The left ventricle showed an increased trabecular pattern in the region of the apex, the mitral annulus was severely dilated with mitral incompetence, the right ventricular out-flow tract (RVOT) was largely dilated with aneurysm of both pulmonary arteries, and there was evidence of pulmonary valve incompetence. Previously, rare cases have been reported of persistent left ventricular non-compaction in patients with congenital left or RVOT obstruction. Non-compaction of the ventricular myocardium is an inherited autosomal dominant disorder; to date, four genes and one genetic locus have been found to be associated with non-compacted ventricular myocardium. The condition is characterized by arrhythmias, thromboembolic events and heart failure, but affected individuals may not be symptomatic. The present case represented a strange association between non-compacted left ventricle, mitral annular dilation with persistence of a normal leaflet and subvalvular mitral valve apparatus, and RVOT dilation with pulmonary artery aneurysms.

Improved graft patency rates and mid-term outcome of diabetic patients undergoing total arterial myocardial revascularization.

OBJECTIVES: Diabetes negatively affects the outcome of patients undergoing percutaneous transluminal coronary angioplasty (PTCA) or coronary surgery. However, data are lacking with respect to the impact of arterial revascularization in the diabetic population. METHODS: Between 1999 and 2003, 100 of 491 diabetics underwent coronary artery bypass graft surgery (CABG) with total arterial grafting (Group 1, G1); these patients were compared with 100 diabetics undergoing conventional CABG with saphenous veins (Group 2, G2), who were matched for Euroscore and other risk factors such as age, obesity, hypertension, left ventricular ejection fraction (LVEF), previous myocardial infarction and chronic obstructive pulmonary disease (COPD). RESULTS: Both groups had a similar number of diseased coronary vessels (G1=2.6 vs G2= 2.7) and received a similar degree of myocardial revascularization (grafted vessels: G1=2.2 vs G2=2.4). Early outcome was comparable between the groups in terms of ventilatory support (G1=10.8±6 vs G2=10.4±5 hours), intensive care unit (ICU) stay (G1=24±12 vs G2=25±14 hours) and major post-operative complications such as atrial fibrillation (G1=26% vs G2=28%), peri-operative myocardial infarction (G1=1% vs G2=2%)and prolonged ventilatory support (G1=6% vs G2=5%). Hospital mortality was 2% in G1 and 3% in G2. Angiography was performed at a mean follow-up of 34 months in 65.9% and 71.1% of hospital survivors of G1 and G2 respectively: patients of G1 showed a significantly higher patency rate (G1=96% vs G2=83.6%, p=0.02). Additionally, patients of G1 showed a significantly lower incidence of recurrent myocardial ischemia (G1=7 pts. vs G2=18 pts., p=0.03), late myocardial infarction (G1=2 pts. vs G2=10 pts., p=0.03) and need for coronary reintervention (G1=1 pt. vs G2=12 pts, p=0.004). CONCLUSIONS: Total arterial grafting in diabetic patients significantly improved the benefits of coronary surgery providing at mid term a higher graft patency rate with a lower incidence of cardiac related events.

Congestive heart failure secondary to right ventricular metastasis of colon cancer. A case report and review of the literature.

Although metastatic tumors of the heart occur more frequently than primary ones, infiltration of the right heart by a metastatic colon cancer has rarely been reported. We report the case of a woman previously operated on for colon cancer, presenting with symptoms of congestive heart failure due to metastatic invasion of the right ventricular cavity. Both transthoracic and transesophageal echocardiography were useful in detecting the mass, but not in defining its nature. The patient underwent a palliative surgical resection of the neoplastic mass but died soon after the intervention.

The BICIRCUIT system: innovative perfusional options for surgical treatment of the thoracic aorta.

PURPOSE: Surgical treatment of the thoracic aorta may become challenging when a rapid switch from left heart bypass (LHB) to cardiopulmonary bypass (CPB) is required. DESCRIPTION: We designed a BICIRCUIT system using a centrifugal pump, a heparinized CPB circuit with a hollow fiber oxygenator, two 3/8 x 3/8 x 3/8 connectors (one placed at the bell inlet draining blood from the left atrium or the venous reservoir and the second placed at the bell outlet directing blood to the oxygenator or femoral artery). Our priming volume was 1100 mL; when switching from LHB to CPB, no additional priming volume was required. The inlet cannula was inserted in the left atrium (for LHB) or femoral vein (for CPB); the outlet cannula was placed in the femoral artery. EVALUATION: We used the BICIRCUIT in 18 patients: 7 patients with a thoracoabdominal aneurysm, 7 patients with a traumatic rupture of isthmic aorta, and 4 patients with a Stanford type B aortic dissection. Conversion to CPB was required in 3 patients because of hemodynamic deterioration and in 1 patient because of hypothermic circulatory arrest. As we observed progressive worsening of blood gases in another patient during LHB, we also used the blood oxygenator without changing the position of the cannulas. No system failures were observed. Postoperative spinal disturbances did not develop in any patients. All patients were successfully discharged. CONCLUSIONS: Our BICIRCUIT system offers three different options: LHB, LHB along with blood oxygenation, and CPB. Each option can be safely achieved and adds to the armamentarium of surgeons and perfusionists in caring for patients with pathology of the thoracic aorta.

Left internal thoracic artery-radial artery composite grafts as the technique of choice for myocardial revascularization in elderly patients: a prospective randomized evaluation.

OBJECTIVES: The technique of choice for myocardial revascularization in elderly patients remains a debated issue. We evaluated the potential advantages of the use of left internal thoracic artery-radial artery composite grafts compared with conventional coronary artery bypass grafts in elderly patients. METHODS: We prospectively enrolled 160 patients aged more than 70 years scheduled to undergo isolated myocardial revascularization. Patients were assigned at random to group 1, 80 patients undergoing total arterial revascularization (left internal thoracic artery on left anterior descending coronary artery plus radial artery), or group 2, 80 patients undergoing standard coronary artery bypass graft surgery (left internal thoracic artery on left anterior descending coronary artery plus saphenous veins). The radial artery was used in all cases as a composite Y-graft. RESULTS: Preoperative characteristics and risk factors (EuroSCORE: group 1 = 7.9 vs group 2 = 8.1), number of grafted coronary vessels (group 1 = 2.4 vs group 2 = 2.5), aortic crossclamping time (group 1 = 37 +/- 7 minutes vs group 2 = 38 +/- 7 minutes), ventilation time (group 1 = 22 +/- 12 hours vs group 2 = 23 +/- 11 hours), intensive care unit stay (group 1 = 39 +/- 10 hours vs group 2 = 40 +/- 9 hours), and hospital mortality (group 1 = 3.8% vs group 2 = 5%) were comparable between the groups. Comparison between the 2 groups in terms of early postoperative complications showed a higher incidence of cerebrovascular accidents in group 2 (group 1 = 0 patients vs group 2 = 4 patients, 5%). At a mean follow-up of 16 +/- 3 months, patients in group 1 showed superior clinical results with a lower incidence of graft occlusion (group 1 = 2 vs group 2 = 11; P =.06) and angina recurrence (group 1 = 2 patients vs group 2 = 12 patients; P =.03). Multivariate analysis identified saphenous vein grafts as independent predictors for graft occlusion and angina recurrence. CONCLUSIONS: Left internal thoracic artery-radial artery composite grafts proved to be a safe procedure in elderly patients. It improved the clinical outcome, providing a significantly higher graft patency rate and a lower incidence of late cardiac events.

Total arterial myocardial revascularization with composite grafts improves results of coronary surgery in elderly: a prospective randomized comparison with conventional coronary artery bypass surgery.

BACKGROUND: Total arterial myocardial revascularization with composite grafts proved to enhance the long-term benefits of coronary surgery. We assessed the hypothesis that full arterial revascularization (FAR) may improve clinical outcome even in elderly and at short term. METHODS AND RESULTS: A prospective randomized study was designed to compare FAR with conventional coronary artery bypass grafting (CABG) surgery [left interval thoracic artery (LITA) on left anterior descending (LAD) plus additional saphenous vein grafts] with the following end points: early and late death, graft occlusion, reintervention, angina recurrence, and acute myocardial infarction (AMI). We enrolled 200 consecutive patients >70 years of age; population was equally divided at random in Group 1 (G1, FAR) and Group 2 (G2, Conventional). The groups resulted comparable with respect to all preoperative continuous and discrete variables and risk factors (Euroscore: G1=8.4 versus G2=8.1). No differences between G1 versus G2 were observed in terms of postoperative complications (perioperative AMI:2% versus 3%), mean intensive care unit (ICU) (hours: 39+/-11 versus 40+/-9) and hospital stay (days: 6+/-2 versus 7+/-3) nor were there any differences in hospital mortality(G1=5% versus G2=4%). At the mean follow-up of 14+/-5 months the incidence of angina recurrence was 3% in G1 versus 12% in G2. Angiographic controls of grafts showed a superior graft patency rate of all the arterial grafts when compared with saphenous vein grafts. Conventional CABG surgery was identified as incremental risk factor for angina recurrence and as predictor for graft occlusion. CONCLUSIONS: Total arterial myocardial revascularization improved clinical outcome of patients undergoing coronary surgery in the elderly, whereas saphenous vein grafts negatively affected patient prognosis in terms of graft patency and freedom from late cardiac events.

Off-pump coronary artery bypass surgery technique for total arterial myocardial revascularization: a prospective randomized study.

BACKGROUND: We investigated whether off-pump coronary artery bypass (OPCAB) surgery should be the procedure of choice in total arterial myocardial revascularization with composite grafts. METHODS: We prospectively enrolled 176 patients undergoing total arterial myocardial revascularization and assigned them at random to one of two groups: group 1 was composed of 88 patients undergoing coronary surgery with cardiopulmonary bypass (CPB); group 2 consisted of 88 patients receiving the OPCAB procedure. We excluded from this study patients with significant risk factors for CPB-related morbidity. Composite arterial grafts in Y-T shape were realized in three different configurations according to patients' characteristics, coronary anatomy, and target stenosis. RESULTS: There were no significant differences between the two groups in terms of preoperative characteristics and risk factors (Euroscore: group 1 = 6.1 +/- 3.5, group 2 = 6.6 +/- 3.8). Mean number of anastomoses was similar in both groups (group 1 = 2.8 +/- 0.8, group 2 = 2.7 +/- 0.5) whereas mean mechanical ventilation time (group 1 = 23 +/- 9 hours, group 2 = 9 +/- 4 hours), intensive care unit stay (group 1 = 43 +/- 6 hours, group 2 = 22 +/- 8 hours), and postoperative stay (group 1 = 7 +/- 3 days, group 2 = 5 +/- 2 days) were significantly reduced in group 2. Early mortality was 2.3% in group 1 and 3.4% in group 2 (p = not significant). Major postoperative complications occurred similarly in the two groups (atrial fibrillation: group 1 = 35.2%, group 2 = 21.6%; myocardial infarction: group 1 = 2.2%, group 2 = 1.1%; stroke: group 1 = 2.2%, group 2 = 0%; abdominal infarction: group 1 = 3.4%, group 2 = 0%). At follow-up (mean, 15 +/- 12 months) no significant differences were observed in terms of survival free of any cardiac-related event (group 1 = 94.3%, group 2 = 96.5%; p = not significant). CONCLUSIONS: Off-pump coronary artery surgery could be successfully used for total arterial grafting without compromising the completeness of revascularization. Avoidance of CPB significantly decreased mechanical ventilation support and length of intensive care unit and postoperative stay; however in the absence of risk factors for cardiopulmonary bypass, off-pump coronary artery surgery did not improve early and midterm clinical outcome.

Is total arterial myocardial revascularization with composite grafts a safe and useful procedure in the elderly?

OBJECTIVE: The aim of the study was to evaluate the mid-term results of total arterial myocardial revascularization (TAMR) with composite grafts in patients older than 70 years when compared to standard CABG technique, since the usefulness of TAMR in the elderly has not been demonstrated yet. METHODS: A prospective randomized study was designed with the following end-points: post-operative complications, death, recurrence of angina, graft occlusion, any cardiac event and reinterventions. One hundred and eighty-eight patients older than 70 years were enrolled and assigned to Group 1(G1)=94 pts, for total arterial revascularization or Group 2(G2)=94 pts, for standard CABG (LITA on LAD plus additional saphenous veins). The groups were comparable in terms of pre-operative characteristics and Euroscore (mean: G1=8.4 vs. G2=8.2). RESULTS: No differences between the groups were observed in terms of mean number of grafted vessels (G1=2.1 vs. G2=2.3), mean aortic cross-clamping time (G1=34+/-8 vs. G2=33+/-6min), mechanical ventilation time (G1=23+/-4 vs. G2=22+/-4hr), ICU stay (G1=40+/-10 vs. G2=39+/-9hr), post-operative complications and hospital mortality (G1=5.3% vs. G2=4.2%). At a mean follow-up of 12+/-4 months, cumulative incidence of angina recurrence was 2.1% in G1 vs. 11% in G2 (P=0.021). Angiographic evaluation showed 98.2% arterial patency in G1 vs. 86% saphenous vein graft patency in G2 (P<0.001). Multivariate analysis identified conventional CABG surgery as independent predictor of angina recurrence, graft occlusion and late cardiac events. CONCLUSIONS: Total arterial revascularization with composite grafts proved to be a safe and effective procedure also in the elderly. Composite arterial grafts provided superior clinical outcome with a lower rate of angina recurrence, graft occlusion and late cardiac events when compared to conventional CABG strategy.

Safety and usefulness of composite grafts for total arterial myocardial revascularization: a prospective randomized evaluation.

OBJECTIVES: To evaluate the results of total arterial revascularization with composite grafts compared with the results of conventional coronary surgery, we enrolled 200 consecutive patient undergoing myocardial revascularization. METHODS: Patients were randomly assigned to 2 groups of 100 patients each: group 1 underwent total arterial revascularization, and group 2 received left internal thoracic artery on left anterior descending artery grafts plus additional saphenous vein grafts. The groups were comparable in terms of continuous and discrete variables and preoperative risk factors. RESULTS: There were no differences between group 1 and group 2 in terms of the number of grafted vessels (mean, 2.8 vs 2.9, respectively), crossclamping time (mean, 38 +/- 7 vs 40 +/- 6 min, respectively), intensive care unit stay (mean, 25 +/- 8 vs 24 +/- 7 hours, respectively), and hospital mortality (1% in both groups) nor were there any differences in postoperative complications. At the mean follow-up of 12 +/- 4 months, patients receiving total arterial revascularization (group 1) showed a better outcome in terms of angina recurrence (group 1 vs group 2: 2 vs 13 patients, P =.007), need of percutaneous transluminal coronary angioplasty reintervention (group 1 vs group 2: 0 vs 8 patients, P =.0012), and actuarial freedom from cardiac events (group 1 vs group 2: 96% vs 67%, P =.006). Angiography carried out in 72% in group 1 and in 68% in group 2 demonstrated a patency rate of 99% of saphenous vein grafts in group 1 and 89% of saphenous grafts in group 2. CONCLUSIONS: Total myocardial revascularization with composite arterial grafts provided superior clinical results and improved patient outcome, even in the short term to midterm. Arterial conduit-related benefits were clearly evident with respect to recurrence of angina and a higher graft patency rate.

Extension de fibras celulosicas con pigmentos inorganicos: a tecnica de "carga en la pared celular" con pulpas de bagazo y un empaste experimental para papel prensa

La industria celulosica enfrenta en la actualidad tres problemas que afectan directamente al medio ambiente 1) la disponibilidad y costo de la materia prima virgen 2) el elevado consumo quimico-energetico requerido para transformar la fibra en papel 3) la magnitud y toxicidad de los efluentes generados en esa transformacion. Entre las diversas alternativas evaluadas se presenta el metodo de "carga en la pared celular" (cell-wall loading) como una tecnica para obtener papeles con alto contenido de cenizas (ultrahigh-ash paper). Se analizan las propiedades fisicas de pulpas semiquimicas de bagazo cargadas internamente por precipitacion in situ de carbonato de calcio