Disección aórtica tipo A: Resultados operatorios y seguimiento a mediano plazo / Surgical results among 100 patients with type A aortic dissection: Retrospective review

Background: Tipe A aortic dissection involves the ascending aorta and has high mortality rates without surgical treatment. Aim: To report the results of surgical treatment of type A aortic dissection. Material and Methods: Retrospective review of medical records of 100 patients aged 17 to 78 years (73 percent males) operated between January 2000 and August 2008, for type A aortic dissection. Follow up was performed with telephone interviews and review of national death records. Results: Eighty three percent of patients had an acute dissection. Operative mortality was 27 and 20 percent for patients with acute and chronic dissection, respectively. Mortality was 50 percent among patients aged 70 years or more, compared with 21 percent among their younger counterparts, The most common complication was bleeding that required a new surgical procedure in 18 percent of patients. Actuarial survival was 70 percent at five years. Cardiovascular problems caused the death of two of the nine patients that died during follow up. Conclusions: Surgical mortality among patients with type A aortic dissection was higher among patients with acute episodes and those aged 70 years or more.

Operación de Ross en Chile / Ross operation in Chile

Background: Donald Ross introduced the pulmonary autografit for aortic valve replacement with reconstruction of the right ventricular outfow tract with a homografit. Despite its advantages over conventional valve prostheses, the Ross Operation is performed in a minority of patients who need an aortic valve replacement throughout the world. Aim: To report the operative and long term results of a series of patients subjected to Ross operation in Chile. Patients and Methods: Between 1996 and 2006, 131 patients aged 35 ± 11 years (62 percent males) were subjected to an aortic root replacement with a pulmonary autografit and reconstruction of the right ventricular outfow tract with a pulmonary homografit. Seventy percent had congenital valve disease. Associated procedures were done in 39 percent. Patients were followed for a mean of 56 ± 30 months. Results: Operative mortality was 2.3 percent. Two patients had the autografits replaced intraoperatively because of tears in the proximal suture line and one within a month of the operation after suffering autografit endocarditis. At last follow up all patients are in functional class 1 or 2. Autografit reoperations were done in two patients who developed dilation with valve regurgitation (both had aortic regurgitation as primary indication for aortic valve replacement). Three patients required reoperation for pulmonary homografit dysfunction. Another three patients had uneventful pregnancies with normal newborns. Actuarial freedom from any reoperation at 10 years is 93 percent. Conclusions: The Ross Operation has low operative morbidity and mortality with excellent long term results. Reoperations have been rare within 10 years of follow up both for the autografit or the homografit.

Presencia de ADN bacteriano en el tejido valvular de pacientes con cardiopatía reumática crónica / Presence of bacterial DNA in valvular tissue of patients with rheumatic heart disease

Background: Rheumatic heart disease (RHD) is a delayed consequence of a pharyngeal infection with Group A streptococcus (GAS), usually ascribed to a cross-reactive immune response to the host cardiac tissues. Acute rheumatic fever (ARF) and its ensuing valvular sequelae are thus considered the prototype of a post-infectious autoimmune disease, with no direct evidence of residual streptococcal antigen in diseased valvular tissues. However, recent studies concerning the antigenic specificity and clonality of intralesional lymphocytes have revealed oligoclonal expansions characteristic of an antigen specific response, that might be related to GAS. Aim: To search for bacterial DNA in valvular tissue from RHD patients and controls. Material and methods: We extracted DNA from surgically excised valve specimens from 15 RHD patients and 6 non RHD controls and tested for the presence of bacterial DNA by Polymerase Chain Reaction (PCR) with primers for 16S rRNA. Results: Eighty percent (12/15) of valve specimens from RHD patients were positive for bacterial DNA, as opposed to none of the valves (n =6) from non RHD controls. Conclusions: These results suggest that GAS might persist in valvular tissue in patients with ARF and contribute to the inflammatory scarring lesion that leads to cardiovascular sequelae.

Resultados del reemplazo valvular aórtico con prótesis mecánica en el Instituto Nacional del Tórax / Early and long term results of mechanical aortic valve replacement at the Instituto Nacional del Torax in Chile

Background: Mechanical aortic valve replacement (AVR) results have been published extensively in industrialized countries. Aim: To assess our immediate and late results in patients subjected to AVR. Patients and Methods: We retrospectively studied 194 patients subjected to isolated AVR between 1995 and 2003. Mean age was 57 ± 13 years and 119 (61%) were male. One hundred thirty nine (73%) were in functional class III-IV, 20 (10%) had a previous cardiac operation and 25 (13%) were operated as an emergency. Surgical indication was stenosis in 110 (58%), regurgitation in 49 (26%) and stenosis/regurgitation in 31 (16%). Etiology was bicuspid valve 56 (29%), degenerative lesions 55 (28%), rheumatic valve disease 38 (20%) and endocarditis 27 (14%). Medtronic Hall was the most common prosthesis used in 157 patients (81%). Mean cardiopulmonary bypass time 97 ± 29 min and mean cross clamp time was 69 ± 21 min. Results: Operative mortality was 4.6% (3% in elective surgery, 16% in emergency surgery and 0% in reoperations). Follow-up was complete in 100% of cases, totalizing 636 patients-year. Survival was 91 ± 2%, 80 ± 4% and 73 ± 6%, at 1, 5 and 7 years, respectively. Multivariate risk analysis identified renal failure and endocarditis as predictors of early and late mortality. During follow up, the linear incidence rate for hemorrhage was 3.29% /patients-year, thromboembolism 2.04% patients-year and endocarditis 1.1% patients-year. Conclusions: AVR has low overall and elective mortality. Midterm survival is good but linear event rates related to anticoagulant treatment are higher than those previously published in industrialized countries. Renal failure and endocarditis were risk factors for early and late death.

Recomendaciones para el estudio microbiológico de tejidos preservados para implantes / Recommendations for the microbiological study of tissues preserved for implants

El uso de los implantes de tejido en medicina ha mejorado el pronóstico y/o la calidad de vida de muchas enfermedades, sin embargo, su utilización no está exenta de riesgos para el receptor. Es por esto que la cuidadosa selección del donante vivo o cadáver y el control microbiológico de los tejidos antes de su utilización son procesos muy importantes para asegurar la calidad del procedimiento. La contaminación de los tejidos puede ser intrínseca (por una infección no diagnosticada en el donante) o extrínseca (una vez que el tejido ya ha sido procurado). Estas recomendaciones se refieren al control microbiológico de las contaminaciones extrínsecas, ya sea durante la manipulación, durante la obtención de los tejidos o durante el procesamiento para la preservación de ellos. Se analizan los implantes de uso más frecuente en nuestro país (válvulas cardíacas, tejido óseo, piel, células progenitoras hematopoyéticas y córnea) y se describe la metodología según datos existentes en la literatura y de procedimientos adaptados de centros foráneos. Dado que ningún implante es absolutamente estéril es muy importante analizar también las recomendaciones frente a cultivos contaminados. Los autores esperamos que este documento sea de utilidad y que en un futuro próximo, podamos exhibir cifras nacionales multicéntricas con metodologías comparables.

Absence of knobs on parasitized red blood cells in a splenectomized patient in fatal falciparum malaria.

We present a case report of fatal falciparum malaria of a splenectomized adult Thai patient. The patient developed high peripheral parasitemia and showed signs of severe malaria with multiorgans involvement. Ultrastructure of Plasmodium falciparum-infected red blood cells in a fatal splenectomized patient and pathological features are reported for the first time with special emphasis on the role of the spleen as a modulating cytoadherence phenotype of parasitized red blood cells (PRBC). In this patient, adherence of the PRBC to the vascular endothelium of brain, kidney and lung including blood circulating cells, was noted, despite the absence of knob on the surface of the PRBC.