Influence of Aging on Microvascular Supply of the Gluteus Medius Tendon: A Cadaveric and Histologic Study.

PURPOSE: The purpose of this cadaveric study was to assess the relation between age and microvascular supply of 3 areas of the gluteus medius tendon using a previously validated CD31 immunohistochemistry staining technique. METHODS: Twenty-four fresh-frozen gluteus medius specimens were obtained through a posterolateral approach to the hip. Specimens aged 18 years or older, of either sex, and of any race were considered for this study. The average age of donors was 47.3 years (range, 18-68 years). Each sample was divided into 3 portions: musculotendinous, tendinous, and tendon-bone junction. H&E staining was used for qualitative structural analysis, and then all samples underwent staining with CD31 immunohistochemistry for quantitative assessment of vessels per square millimeter. A comparison of the microvessel density between zones according to age was performed by an analysis of variance. To evaluate the relation between microvessel supply and age, a regression model with curvilinear estimation was used. The data were fitted to a quadratic model. RESULTS: Vascular supply in transversal and longitudinal cuts regardless of the zone was, on average, 53.9 ± 32.1 vessels/mm2 and 51.1 ± 19.3 vessels/mm2, respectively. All the areas of the tendon showed a strength of relation (R) ranging from 0.41 to 0.76 between age and vascular supply. In addition, the proportion of vascular supply change explained by age (R2) was significant in most cases (ranging from 0.17 to 0.56, with P < .05). CONCLUSIONS: There is a chronological relation between aging and microvascular supply of the gluteus medius tendon, in which an initial increase occurs from 18 years of age to 30 to 40 years of age, with a progressive decrease after 50 years of age. CLINICAL RELEVANCE: The findings of our study may have implications for increased vulnerability of the gluteus medius tendon and decreased healing potential.

Iliopsoas Muscle/Tendon Proportions at Three Levels of Described Arthroscopic Tenotomy: An Anatomic Study in Fresh Cadaveric Specimens.

PURPOSE: To calculate the iliopsoas muscle/tendon ratio at 3 levels of arthroscopic iliopsoas tenotomy sites in fresh cadaveric specimens. METHODS: An anatomic study design was performed using 16 iliopsoas musculotendinous units from the level of the hip joint to their insertion on the lesser trochanter. All specimens came from 16 fresh cadaveric specimens (10 male, 6 female), with a median age of 41 years (range 31-55.25 years). Circumferential measurements of the composite musculotendinous unit and the iliopsoas tendon were then made at the lesser trochanter insertion, the site of transcapsular tenotomy, and the site of tenotomy at the level of the labrum. Anatomical variance of the iliopsoas tendon at the insertion on the lesser trochanter and muscular extension below the lesser trochanter level also were described. The difference between the median circumference of the iliopsoas musculotendinous units or the isolated tendons at the 3 levels was calculated. RESULTS: The median circumference of the iliopsoas musculotendinous unit at the level of the labrum, orbicularis zone (transcapsular tenotomy site), and the lesser trochanter was 140.9 mm (range 137.9-148.9), 136.7 mm (range 132.9-140), and 99.5 mm (range 96.5-104.8), respectively. The median circumference of the iliopsoas tendon at these same levels was 25.6 mm (range 22.7-33.7), 28.9 mm (range 25.1-32.2), and 30.9 mm (range 27.9-36.1), respectively. Accordingly, the proportions of the iliopsoas muscle/tendon at the level of the labrum, the transcapsular tenotomy site, and the lesser trochanter insertion were 18% tendon/82% muscle, 21% tendon/79% muscle, and 31% tendon/69% muscle, respectively. CONCLUSIONS: The proportions of the iliopsoas muscle/tendon at the level of the labrum, the transcapsular tenotomy site and the lesser trochanter insertion were 18% tendon/82% muscle, 21% tendon/79% muscle, and 31% tendon/69% muscle, respectively. The distal muscular projection below the tendinous insertion on the lesser trochanter may maintain the functional connection of the iliopsoas between origin and insertion even after releasing the tendon. CLINICAL RELEVANCE: This finding may have implications for a new understanding of arthroscopic tenotomy of the iliopsoas around the hip, as previously described muscle/tendon proportions were not calculated in fresh cadavers.

The regional microvascular density of the gluteus medius tendon determined by immunohistochemistry with CD31 staining: a cadaveric study.

BACKGROUND AND PURPOSE: There are no studies to date about the vascularisation into the gluteus medius tendon. The purpose of this study was to define the microvessel density of the gluteus medius in 3 zones through a special staining with CD31 and to identify regional differences in microvascular density that may have implications for the healing. METHODS: We obtained 12 complete gluteus medius tendons from cadavers who had been an average age of 30.3 years old (range 18 to 55). All the donors were males with no known history of hip abnormalities.Following a rigorous protocol, each gluteus medius tendon was divided in 3 portions. Each gluteus medius tendon was divided in 3 portions (I: musculotendinous, II: Tendon, III: Tendon-Bone junction). RESULTS: There were regional differences between all anatomic zones in both the transverse section (p<0.001) and the longitudinal section (p = 0.007). Furthermore, a significant difference was found between zones II and I (mean difference -23.45 IC95% -38.77 to -8.13, p<0.001) and between zones II and III (mean difference -26.08 IC95% -41.39 to -10.76, p<0.001) in transverse section. In longitudinal sections, this difference was found as well between zones II and I (mean difference -29.48 IC95% -51.54 to -7.43, p = 0.01), but not between zones II and III (mean difference -10.87 IC95% -32.93 to 11.18, p = 0.67). CONCLUSIONS: The microvessel density was significantly lower in the length of the tendon (central portion) compared to the other 2 regions.

Evaluación hemodinámica no invasiva con cardiografía de impedancia: aplicaciones en falla cardíaca y en hipertensión arterial / Non-invasive hemodynamic evaluation with impedance cardiography: applications in heart failure and hypertension

La cardiografía de impendancia (CGI) representa un método no invasivo para la evaluación del estado hemodinámico latido a latido. Aunque se introdujo por primera vez hace más de 40 años, la CGI ha mostrado un resurgimiento en la última década, a partir de una serie de estudios clínicos que han demostrado su precisión en la estimación del volumen latido, tanto contra el "gold-standard" invasivo (termodilución), como contra los métodos de referencia no invasivos (ecocardiografía). Diversos estudios demuestran la utilidad de esta técnica en el manejo del paciente con falla cardíaca y en el enfoque diagnóstico y terapéutico de la hipertensión arterial, por lo cual constituyen actualmente dos de las aplicaciones clínicas más importantes de la CGI. En falla cardiaca, los cambios en el volumen de líquido del tórax y del gasto cardíaco evaluados por CGI, han demostrado ser predictores de descompensación aguda, incluso semanas antes del inicio de la sintomatología respiratoria; además, permiten identificar el origen cardiogénico o respiratorio de la disnea cuando el examen físico y los demás paraclínicos no son concluyentes. En los pacientes con hipertensión arterial no controlada o resistente, la CGI permite realizar una mejor caracterización del fenotipo hipertensivo y elegir la estrategia farmacológica más específica para intervenir la alteración hemodinámica predominante (resistencia vascular vs. gasto cardiaco elevado). En este artículo se realiza una revisión de los principios biofísicos de la CGI y su utilidad en la evaluación no invasiva del estado hemodinámico, así como una evaluación crítica de la literatura que da soporte a su aplicación clínica en el tratamiento de la falla cardíaca y la hipertensión arterial.

Impedance cardiography (ICG) represents a non-invasive method for hemodynamic assessment in a beat-to-beat basis. Since its introduction more than forty years ago, a renewed interest in the use of this technique during the last decade has been noticed, mainly as a result of a series of clinical studies showing its precision in the estimation of stroke volume either against invasive gold standard (i.e. thermodilution) or against non-invasive reference methods (i.e. echocardiography). On the other hand, ICG has demonstrated to be useful for the management of heart failure patients and for the diagnostic and therapeutic approach to hypertension, which currently constitute two of the major applications of ICG. In heart failure patients, changes in thoracic fluid content and cardiac output tracked by ICG have shown to be predictors of acute decompensation even weeks before respiratory symptoms appear; also allowing identification of a cardiac vs. respiratory origin of dyspnea when physical examination and laboratory tests are not conclusive. In the particular case of patients with uncontrolled or severe hypertension, ICG makes possible a better characterization of hypertensive phenotype leading to a more specific choice of pharmacological agents to treat the primary hemodynamic alteration (i.e elevated peripheral resistance vs. elevated cardiac output). The present review, provides a review of the biophysical principles of ICG and its precision in measuring stroke volume and present a critical assessment of the literature supporting its clinical application in the management of heart failure and arterial hypertension.

Analisis en tiempo y frecuencia de la variabilidad R-R en deportistas y sedentarios / Analysis of time and frecuency of H-R variability in athletes and sedentary people

Objetivo. Comparar el comportamiento de la variabilidad de la frecuencia cardíaca (VFC) en registros de corta duración en reposo entre pesistas, atletas de resistencia aeróbica y personas sedentarias, utilizando métodos del dominio de la frecuencia y el tiempo. Métodos. Después de un período de reposo de 15 minutos en decúbito supino, se realizaron registros de la frecuencia cardíaca a un grupo de 17 atletas de resistencia aeróbica, 15 pesistas y 19 personas sedentarias, utilizando un monitor telemétrico de latidos cardíacos, durante ocho minutos y bajo respiración controlada. Con un software en plataforma Matlab®, se acondicionó la señal y se tomaron 235 datos para la construcción de los tacogramas y su posterior análisis en el dominio de la frecuencia y el tiempo. Resultados. Se encontró una frecuencia cardíaca promedio menor en los atletas de resistencia aeróbica. Todas las mediciones en el dominio del tiempo fueron mayores en los atletas de resistencia aeróbica. No hubo diferencias entre los grupos en los componentes espectrales de alta frecuencia (HF) y baja frecuencia (LF) en unidades normalizadas y en la relación LF/HF. Conclusiones. En los atletas de resistencia aeróbica se encuentra una marcada bradicardia. Las diferencias encontradas en el dominio del tiempo no se evidenciaron en el dominio de la frecuencia. Las adaptaciones producidas por el entrenamiento de larga duración, en los mecanismos centrales que modulan la frecuencia respiratoria o en las células del nodo sinusal, pueden ser las responsables de las diferencias encontradas en la modulación de la frecuencia cardíaca en los deportistas.