14. Definición: Hipertrofia miocárdica inapropiada en ausencia de una causa obvia como HTA o estenosis aórtica. Genético : presencia de mutaciones en los genes que codifican las proteínas sarcoméricas Fenotípico : presencia de una hipertrofia miocárdica de causa desconocida en ausencia de alteraciones de la poscarga Histológico : aparición de fibrosis, desorganización del miocardio ( disarray ) y afectación de los vasos de pequeño calibre.
15.
16. Corazón normal HCM con disarray Tricromo Masson Gene Reviews. University of Washington
El Homenaje a Arago es un monumento parisino inaugurado en 1994, que se compone de 135 medallones incrustados en el pavimento de París, y que señalan el recorrido del Meridiano de París por la capital francesa. Dibujan una línea de 17 km de largo que cruza la ciudad de norte a sur.
Único jugador en realizar 4 tapones en un solo partido a Michael Jordan. Era el que reemplazaba a Larry Bird luego de retirarse
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In histopathological studies, there is an 8-fold increase in the amount of matrix collagen in adults and children who die suddenly from HCM compared with normal control subjects
50% casos con agregacion familiar #1 causa de muerte subita en atletas Symptoms are caused by intraventricular, usually LV outflow tract (LVOT) obstruction, myocardial ischemia and reduced coronary vasodilator flow reserve, diasto- lic dysfunction and arrhythmias. Tb pueden ser asintomáticos.
HCM is characterized by a disorganization and malalignment of the myofibrils, i.e. myofibrillar disarray , which is not unique to HCM but is clearly more extensive in this disorder than in secondary myocardial hypertrophy from pressure overload or congenital heart disorders. It is likely that the capillary density in the hypertrophied heart is inadequate relative to the increased myocardial mass .·. IAM In 70% of patients, the ventricular septum and anterior LV wall are involved. Less frequent locations of myocardial hypertrophy include: the mid-portion of the ventricular septum, the apex, and the lower portion of the septum. Severe concentric hypertrophy may occur and papillary muscles may also be hypertrophied The end-diastolic LV wall thickness is typically greater than 15 mm. In some patients, HCM might be associated with massive myocardial hypertrophy (wall thickness of 45–50 mm) 25% of patients with HCM have a dynamic outflow tract obstruction caused by a narrowed LVOT and abnormal systolic anterior motion of the mitral valve. In nearly all patients with LVOT obstruction, the outflow tract area is smaller than 4.0 cm2 (mean: 2.6±0.7 cm2). In patients without obstruction and normal subjects, the outflow tract area is 5.9±1.6 cm2 and 10.4±1.2 cm2, respectively. During onset of cardiac systole, deformation and bulging of the hypertrophied septum into the LVOT contributes to the flow acceleration in the narrowed LVOT. The subsequent pressure drop leads to an anterior movement, and eventually apposition of the anterior mitral valve leaflet to the septum during systole contributes to the outflow obstruction (the “ Venturi effect ” ) o chupón. The LVOT obstruction may be present at rest (resting obstructive HCM) or may be provoked by exercise, Valsalva manoeuvre, or administration of amyl nitrite (latent obstructive HCM). The anterior mitral valve leaflet motion causes a secondary mitral valve regurgitation, occurring in mid-late systole. In some patients, mitral regurgitation might be severe and contribute substantially to symptoms of heart failure. The pressure gradient in the LVOT is used to determine the haemodynamic relevance of the LVOT obstruction. Pressure gradients can be calculated by a modified Bernoulli formula, according to which maximal flow velocities across a stenosis reflect the severity of obstruction. It is clearly recognized that not all patients have severe outflow tract pressure gradients, while abnormalities in diastolic function are common. At present, diastolic dysfunction is thought to be one of the major pathophysiological mechanisms present in all patients with HCM, frequently leading to diastolic heart failure. The less common apical form of HCM has a high prevalence in Japan. Another form of HCM is mid-ventricular hypertrophy. These patients present with a gradient between the LV apical region and the remainder of the chamber. This may progress to a non-contractile apical aneurysm with apical thrombus formation. MRI The arsenal of MRI sequences usable in HCM includes: SE-MRI; cine MRI; velocity-encoded MRI; MRI tagging; CE-IR MRI; and MR spectroscopy. The presence, distribution and severity of the hypertrophic process can precisely be evaluated with SE MRI and cine MRI. An advantage of MRI over other cardiac imaging modalities is the use of angled planes, which allows accurate measurement of the myocardial wall thickness. In the asymmetric septal form of HCM, the mean ratio of septal-to-free wall thickness is higher than 1.5±0.8, compared with 0.9±0.3 in normal volunteers and 0.8±0.2 in patients with LV hypertrophy. Using cine MRI sequences, obstructive forms can be differentiated from non-obstructive forms of septal HCM. Flow acceleration and turbulence in the narrowed LVOT causes a dispersion of spin magnetization, generating a signal void in the LVOT during systole. Presence of signal void in early systole is indicative of severe obstructive HCM. Mid-systolic signal voids usually represent less severe (latent) obstructions. In non-obstructive forms of HCM and in normal subjects, usually no signal voids are found. The concomitant regurgitant jet through the mitral valve is also visible as an area of signal void. Velocity-encoded cine MRI can be used to quantify flow velocities in the narrowed LVOT, and to assess the mitral valve regurgitation. A combination of imaging planes is required to optimally image the LVOT and mitral valve abnormalities. These include longitudinal views through the LVOT; combined LV in- and outflow views; horizontal and vertical long-axis views through the mitral valve; views perpendicular through the LVOT (to measure the LVOT area); and views through the mitral valve plane (to quantify the mitral regurgitation). In the thickened myocardial regions, however, systolic wall thickening is markedly reduced, which is related to muscle disorganization
cardiovascular death, unplanned cardiovascular hospital stay, sustained ventricular tachycardia or ventricular fibrillation, or appropriate implantable cardioverter-defibrillator (ICD) discharge HF end point included unplanned HF hospital stay, progression to New York Heart Association (NYHA) functional class III or IV status, or HF- related death.
La resonancia magnética (RM) con contraste se utiliza desde 1982, inicialmente para la valoración del infarto de miocardio en un momento en el que se empleaban trazadores basados en el manganeso. El compuesto Gd-DTPA presenta una rápida difusión hacia el exterior de los capilares y alcanza el tejido, pero NO puede atravesar las membranas celulares intactas. Por eso, tras un bolo intravenoso se observa una acumulación pasiva del Gd-DTPA, tanto en el miocardio normal como en el patológico. Sin embargo, con el paso del tiempo, debido a su cinética más lenta y a su mayor volumen de distribución, el miocardio patológico muestra una cantidad ligeramente mayor de Gd-DTPA por unidad de volumen. Fueron pocos los progresos realizados en este campo, hasta que en 1991 se desarrolló una secuencia RM denominada de «inversión-recuperación. El operador selecciona visualmente un parámetro (TI [tiempo hasta la inversión], el tiempo transcurrido hasta el punto de anulación), de manera que se elimina el miocardio de fondo, que no envía ningún tipo de señal y que aparece como una estructura negra.
DTPA: acido dietilen triamin penta acético, Bayer TLVM%: porcentaje de la masa total VI Después de la obtención de los planos localizadores habituales, se obtuvieron imágenes de cine-RM con una secuencia Steady-State Free-Precession en cortes orientados sobre el eje longitudinal del ventrículo izquierdo, así como múltiples cortes de 10 mm de grosor orientados en el eje transversal que cubrían desde la base hasta el ápex del ventrículo izquierdo. Se adquirieron un mínimo de 16 fases del ciclo cardiaco para cada corte y se reprodujeron en forma de asa continua. Se inyectaron 0,1 mmol/kg de gadoterilol intravenoso (Gadovist®s, Schering AG, Berlín, Alemania) y se adquirió, a los 10 min de la inyección de contraste, una secuencia eco-gradiente 3D inversión-recuperación para analizar el RT. El tiempo de inversión se ajustó para anular la señal del miocardio normal (200-300 ms). Esta secuencia se programó en múltiples cortes sobre el eje transversal del ventrículo izquierdo, utilizando la misma orientación que para las imágenes de cine-RM
risk of SCD (approximately 0.5%/year) It is only recently that fibrosis in HCM could be detected noninvasively in vivo with the CMR LGE technique, where gadolinium-contrast agents accumulate in areas of intersti- tial expansion due to fibrosis, which can then be imaged In this study we used an established and validated method of quantification based on the FWHM technique. Several groups have recently shown that this technique correlates accurately with ex vivo quan- tification of fibrosis and has the best reproducibility. Work by Spiewak et al. (24) has demonstrated no significant difference between techniques for quantifying fibrosis in HCM on the basis of 6 SDs and FWHM thresholding methods compared with visual anal- ysis, with the best intraobserver agreement noted for the FWHM method.
Comparison of (a) in vivo diastolic cine image, (b) in vivo gadolinium-enhanced cardiovascular magnetic resonance, (c) gross specimen of sections from an explanted heart, and (d) histologic sections stained with sirius red. All images are to the same scale. After fixation, considerable contraction has occurred. Regions of gadolinium enhancement correlate with regions of macroscopic unstained pale myocardium and regions of red-stained collagen. A representative mesocardial region, which is well defined, is marked by an arrow.
El efecto Venturi (también conocido tubo de Venturi) consiste en que un fluido en movimiento dentro de un conducto cerrado disminuye su presión al aumentar la velocidad después de pasar por una zona de sección menor. Si en este punto del conducto se introduce el extremo de otro conducto, se produce una aspiración del fluido contenido en este segundo conducto. Este efecto, demostrado en 1797, recibe su nombre del físico italiano Giovanni Battista Venturi (1746-1822). El efecto Venturi se explica por el Principio de Bernoulli y el principio de continuidad de masa. Si el caudal de un fluido es constante pero la sección disminuye, necesariamente la velocidad aumenta tras atravesar esta sección. Por el teorema de la conservación de la energía mecánica, si la energía cinética aumenta, la energía determinada por el valor de la presión disminuye forzosamente.
Potential Role of CMR in Management of HCM This figure explains the potential utility of cardiac magnetic resonance (CMR) in the diagnosis and management of HCM. It has a potential role in establishing the diagnosis, pre-procedural planning, and prognostication. LV = left ventricular; other abbreviations as in Figure 1.