Alcaligenes xylosoxidans endocarditis of a prosthetic valve and pacemaker in a 62-year-old woman.

The bacterium Alcaligenes xylosoxidans is known to cause several nosocomial infections; however, it rarely causes endocarditis, which has a very high mortality rate. Early isolation of the infection source and prompt identification of the patient's antibiotic sensitivities are paramount if the infection is to be treated adequately. We present what is apparently only the second documented case of the successful eradication of bioprosthetic valve endocarditis that was caused by pacemaker lead infection with Alcaligenes xylosoxidans. A 62-year-old woman with multiple comorbidities presented with endocarditis of a recently placed bioprosthetic aortic valve. The infection was secondary to pacemaker lead infection. She underwent antibiotic therapy, but an unusual pattern of antibiotic resistance developed. Despite initially adequate therapy, the infection recurred because of virulence induced by antibiotic resistance. Emergent, high-risk surgical treatment involved excising the infected valve and removing the source of the infection (the pacemaker leads). The patient eventually recovered after prolonged antibiotic therapy and close vigilance for recurrent infection. In addition to the patient's case, we discuss the features of this bacteremia and the challenges in its diagnosis.

Pharmacokinetics of doxycycline in sheep after intravenous and oral administration.

The pharmacokinetics of doxycycline were investigated in sheep after oral (PO) and intravenous (IV) administration. The IV data were best described using a 2- (n = 5) or 3- (n = 6) compartmental open model. Mean pharmacokinetic parameters obtained using a 2-compartmental model included a volume of distribution at steady-state (V(ss)) of 1.759+/-0.3149L/kg, a total clearance (Cl) of 3.045+/-0.5264mL/kg/min and an elimination half-life (t(1/2beta)) of 7.027+/-1.128h. Comparative values obtained from the 3-compartmental mean values were: V(ss) of 1.801+/-0.3429L/kg, a Cl of 2.634+/-0.6376mL/kg/min and a t(1/2beta) of 12.11+/-2.060h. Mean residence time (MRT(0-infinity)) was 11.18+/-3.152h. After PO administration, the data were best described by a 2-compartment open model. The pharmacokinetic parameter mean values were: maximum plasma concentration (C(max)), 2.130+/-0.950microg/mL; time to reach C(max) (t(max)), 3.595+/-3.348h, and absorption half-life (t(1)/(2k)(01)), 36.28+/-14.57h. Non-compartmental parameter values were: C(max), 2.182+/-0.9117microg/mL; t(max), 3.432+/-3.307h; F, 35.77+/-10.20%, and mean absorption time (MAT(0-infinity)), 25.55+/-15.27h. These results suggest that PO administration of doxycycline could be useful as an antimicrobial drug in sheep.

Mitral valve operations through standard and smaller incisions.

OBJECTIVE: Evaluate the operative results of mitral valve repair (MVV) and mitral valve replacement (MVR) performed through standard and smaller incisions. METHODS: From January 1997 through December 2002, 821 consecutive patients underwent mitral valve operation. Of these procedures, 475 were MVV and 346 were MVR. A logistic regression model was developed to identify the risk factors for early mortality and to evaluate the effect of replacement versus repair and standard versus small incision. RESULTS: Replacement patients were older, more likely New York Heart Association (NYHA) class III or IV, more likely female, and had more frequent previous median sternotomy and stroke (all P <.05). The mitral diagnoses in the 2 groups were markedly different. Prolapse and ischemia dominated the repairs, whereas calcific and rheumatic diagnoses required replacement. There were 667 concomitant procedures performed on these patients, most commonly coronary artery bypass graft (229), aortic valve replacement (170), maze (79), and tricuspid valve (TV) repair/replacement (73). Thirty-three patients (4.0%) died in the postoperative period, 2.3% after repair and 6.4% after replacement ( P <.01). Endocarditis (4/17), calcific disease (7/73), and ischemic disease (9/121) accounted for 26% of patients and 60% of deaths. Multivariate regression analysis identified NYHA class, emergent status, concomitant TV operation, and history of renal failure, but not repair versus replacement, as independent risk factors predicting mortality. We estimated that 356 of the 821 patients (43%) were candidates for small-incision operations, the others were excluded by the need for concomitant procedure or other cause. A total of 205/356 (57%) actually underwent small-incision operations, all with central cannulation and standard techniques. From 1997-1999, 32% of eligible patients were so treated, but from 2000-2002, with increasing surgeon experience, this percentage rose significantly to 71% ( P <.01). Eligible patients who underwent small-incision operation were younger and had lower NYHA classifications, lower preoperative creatinine, and shorter length of stay (all P <.01) than those who had standard incisions. Cross-clamp time, perfusion time, and mortality rate were not significantly different. CONCLUSIONS: The mortality rate for MV operations is concentrated among a few diagnoses. In some patients surgery may be approached safely through smaller incisions without introducing new elements of operative risk.

The risks and benefits of reoperative aortic valve replacement.

BACKGROUND: Many patients are advised to have mechanical aortic valve replacement (AVR) because their expected longevity exceeds that of tissue prostheses. This strategy may avoid the risks of reoperation but exposes patients to the risks of long-term anticoagulation therapy. Which risk is greater? METHODS: We reviewed the records of 1213 consecutive, unselected AVR patients, 60% of whom had concomitant procedures, who were treated from 1994 through 2002. Of these patients, 887 were first-time AVR patients, and 326 underwent reoperation. Of the reoperation patients, 134 had previously undergone AVR (redo). We constructed a risk model from these 1213 cases to assess the factors that predicted mortality and to examine the extent to which reoperation affected outcome. RESULTS: Multiple logistic regression analysis indicated that factors of reoperation and redo operation did not predict mortality. In fact, the mortality rate was 4.1% for all first AVR operations and 3.1% for all reoperation AVR ( P =.891). Significant predicting factors (with odds ratios) were reoperative dialysis (6.03), preoperative shock (3.68), New York Heart Association class IV (2.20), female sex (1.76), age (1.61), and cardiopulmonary bypass time (1.26). CONCLUSIONS: In this series, the risk of reoperation AVR is comparable with the published risks of long-term warfarin sodium (Coumadin) administration after mechanical AVR. Any adult who requires AVR may be well advised to consider tissue prostheses.

Biventricular pacing during cardiac operations.

BACKGROUND: Biventricular pacing (resynchronization therapy) improves the duration and quality of life in a subset of patients with congestive heart failure, but this technique has received little attention in the cardiac surgery literature. This report presents some preliminary ideas about its rationale and technique, and some likely indications for this procedure during the performance of cardiac operations. METHODS: We briefly summarize the theory and the results of the randomized clinical trials of resynchronization therapy that led us to consider biventricular pacing for high-risk cardiac surgery patients. We present s ome techniques for using temporary and permanent biventricular pacing in the operating room. We review the hospital records and present early results of the first 25 patients in whom we implanted permanent left ventricular free wall pacing electrodes with the intent of implanting biventricular pacing devices. CONCLUSIONS: Biventricular pacing has great potential to simplify the management and improve the outcomes of some cardiac surgical patients.

Routine enlargement of the small aortic root: a preventive strategy to minimize mismatch.

BACKGROUND: We routinely use aortic root enlargement (ARE) as part of one strategy to avoid prosthesis-patient mismatch in patients with relatively small aortic roots who are undergoing aortic valve replacement (AVR). METHODS: We performed a retrospective review of 657 consecutive stented AVR patients at a single institution between 1995 to 2001. Of these, 114 (17%) patients underwent ARE. Root enlargement was selectively performed in patients at risk for prosthesis-patient mismatch, defined as calculated projected indexed effective orifice area (iEOA) less than 0.85 cm2/m2. This involved extension of the aortotomy between the left and noncoronary cusps, valve implantation, and Dacron patch closure of the aorta, thus permitting replacement with a valve size appropriate to body surface area. RESULTS: The mean age of ARE patients was 72.5 +/- 11.0 years, with 32% aged 80 years or more. Of the patients, 61% were female and 27% had undergone previous cardiac operations. Combined procedures included coronary bypass in 57 patients and mitral repair or replacement in 24. The prevalence of mismatch was less than 3%. The ARE required an average of 19 minutes of additional aortic clamp time. The 30-day mortality was 0.9%. Logistic regression showed perfusion time to be the only independent predictor of mortality. CONCLUSIONS: Our results show that ARE can be performed readily and with minimal added risk relative to standard AVR. We also present a preventive strategy to minimize mismatch predicted at time of operation from the reference value of effective orifice area for a given prosthesis and the patient's size. This includes use of ARE to enhance the potential benefit of AVR.

Sistematización de la implementación del modelo pedagógico en el nuevo currículo de la Facultad de Medicina de la Universidad de Antioquia / The hour of change for the Faculty of Medicina, University of Antioquia, Medellín, Colombia

Comenzada ya esta primera centuria del tercer milenio, y cuando se empieza a apuntalar el andamiaje que nos llevará a un futuro cargado de promesas, de esperanzas y también de sorpresas, nuestra Facultad de Medicina tiene ya su maletín de viaje empacado con las provisiones que el último decenio aconsejara en prolongados y fructíferos esfuerzos por diseñarlo de antemano. Esta vez el cambio no nos tomó por sorpresa; en esta ocasión, la universidad como un todo aclimató en su interior la cultura de organización previsora, y de empresa que aprende de su propia experiencia, y el despuntar del nuevo siglo la encuentra ya ensayando a plena máquina y con responsabilidad la nueva propuesta pedagógica, sumum de los logros que deja como legado la pedagogía del período histórico que termina, y en el cual los avances no son fruto de inercia alguna sino cosecha arrancada en surcos húmedos y dolorosamente estrechos. El estudio que presenta IATREIA hoy no es la epopeya de exitosos logros en esta empresa que, aunque madura, apenas comienza. Es, sí, el recuento con pausa de acciones largamente pensadas y de frutos por decenios añorados, que en forma frágil y apenas como amagos de retoño inician su despunte y hacen guiños, que sólo concretaremos con la unión de esfuerzos y voluntades con los que fueron concebidos y sin los cuales difícilmente fraguarán. Currículo flexible y pertinente; formación integral, interdisciplina, aprendizaje crítico, reflexivo y creativo, modelos de autoconstrucción del aprendizaje, formación ciudadana, formación profesional, investigación de punta, investigación didáctica y compromiso con la ciencia y con lo social, son apenas algunos de los núcleos generadores que orientan la propuesta y cuya implantación y crecimiento se halla en ciernes cuando no apenas en semilla.