Morphological Assessment and Possible Clinical Implications of the Left Ventricle Papillary Muscles. Study in a Colombian Population Sample

SUMMARY: Papillary muscles in the left ventricle present multiple anatomic expressions that are relevant for medical fields focusing on the understanding of clinical events involving these structures. Here, the aim was to perform a morphological characterization of the left ventricle papillary muscles in a sample of Colombian population. In the study were included eighty-two hearts from male individuals who underwent autopsy at the Institute of Legal Medicine and Forensic Sciences in Bucaramanga, Colombia. In each heart was carefully performed a longitudinal incision on the obtuse margin to visualize the papillary muscles. Data set was registered, and analysis of the continuous and categorical variables was carried out. Single anterior papillary muscle was observed in 74 samples (90.2 %) whereas this represented only 48 specimens (58.5 %) for the posterior papillary muscle (p = 0.3). Mean length and breadth of the anterior muscle were 29.9 ± 4.94 and 11.74 ± 2.75 mm, and those for the posterior muscle were 27.42 ± 7.08 and 10.83 ± 4.08 mm. Truncated apical shape was the most frequent type observed on the papillary muscles, anterior 41 (50 %) and posterior 37 (45.1 %), followed by flat-topped in the anterior 25 (30.5 %) and bifurcated in posterior muscle 14 (17.1 %). A mean of 9.04 ± 2.75 chordae raised from the anterior and 7.50 ± 3.3 from posterior papillary muscle. In our study we observed a higher incidence of single papillary muscles and slightly larger dimensions than information reported in the literature. The anatomic diversity of the papillary muscles should be considered for the correct image interpretation, valve implantation and performance evaluation on myocardial ischemic events.

Los músculos papilares del ventrículo izquierdo presentan múltiples expresiones anatómicas que son relevantes para las áreas médicas que se centran en la comprensión de los eventos clínicos que involucran estas estructuras. El objetivo fue realizar una caracterización morfológica de los músculos papilares del ventrículo izquierdo en una muestra de población colombiana. En el estudio se incluyeron ochenta y dos corazones de individuos masculinos a los que se les realizó autopsia en el Instituto de Medicina Legal y Ciencias Forenses de Bucaramanga, Colombia. En cada corazón se realizó cuidadosamente una incisión longitudinal en el margen obtuso para visualizar los músculos papilares. Se registró el conjunto de datos y se realizó el análisis de las variables continuas y categóricas. Se observó un solo músculo papilar anterior en 74 muestras (90,2 %), mientras que este rasgo se presentó en 48 muestras (58,5 %) para el músculo papilar posterior (p = 0,3). La longitud y anchura media del músculo anterior fueron 29,9 ± 4,94 y 11,74 ± 2,75 mm, y las del músculo posterior fueron 27,42 ± 7,08 y 10,83 ± 4,08 mm. La forma apical truncada fue el tipo más frecuente observado en los músculos papilares, anterior 41 (50 %) y posterior 37 (45,1 %), seguido de la forma plana en los 25 anteriores (30,5 %) y bifurcada en el músculo posterior 14 (17,1 %). Una media de 9,04 ± 2,75 cuerdas elevadas desde el músculo papilar anterior y 7,50 ± 3,3 desde posterior. En nuestro estudio observamos una mayor incidencia de músculos papilares únicos y dimensiones ligeramente mayores que la información reportada en la literatura. La diversidad anatómica de los músculos papilares debe ser considerada para la correcta interpretación de imágenes, implantación valvular y evaluación del desempeño en eventos isquémicos miocárdicos.

Mechanical complications in STEMI: prevalence and mortality trends in the primary PCI era. The Ruti-STEMI registry.

INTRODUCTION AND OBJECTIVES: Mechanical complications confer a dreadful prognosis in ST-elevation myocardial infarction (STEMI). Their prevalence and prognosis are not well-defined in the current era of primary percutaneous coronary intervention (pPCI) reperfusion networks. We aimed to analyze prevalence and mortality trends of post-STEMI mechanical complications over 2 decades, before and after the establishment of pPCI networks. METHODS: Prospective, consecutive registry of STEMI patients within a region of 850 000 inhabitants over 2 decades: a pre-pPCI period (1990-2000) and a pPCI period (2007-2017). We analyzed the prevalence of mechanical complications, including ventricular septal rupture, papillary muscle rupture, and free wall rupture (FWR). Twenty eight-day and 1-year mortality trends were compared between the 2 studied decades. RESULTS: A total of 6033 STEMI patients were included (pre-pPCI period, n=2250; pPCI period, n=3783). Reperfusion was supported by thrombolysis in the pre-pPCI period (99.1%) and by pPCI in in the pPCI period (95.7%). Mechanical complications developed in 135 patients (2.2%): ventricular septal rupture in 38 patients, papillary muscle rupture in 24, and FWR in 73 patients. FWR showed a relative reduction of 60% in the pPCI period (0.8% vs 2.0%, P<.001), without significant interperiod changes in the other mechanical complications. After multivariate adjustment, FWR remained higher in the pre-pPCI period (OR, 1.93; 95%CI, 1.10-3.41; P=.023). At 28 days and 1 year, mortality showed no significant changes in all the mechanical complications studied. CONCLUSIONS: The establishment of regional pPCI networks has modified the landscape of mechanical complications in STEMI. FWR is less frequent in the pPCI era, likely due to reduced transmural infarcts.

Primer caso en Colombia de crioablación y mapeo de alta densidad en arritmia ventricular del músculo papilar / First case in Colombia of cryoablation and high-density mapping in ventricular arrhythmia of the papillary muscle

Resumen La ablación con catéter se ha convertido en un enfoque práctico para el tratamiento de las arritmias cardiacas, sobre todo cuando el manejo farmacológico óptimo no logra controlarlas. De esta manera se reduce la readmisión hospitalaria y se mejora la calidad de vida de los pacientes, incluso de aquellos en quienes no se logra la resolución completa de la arritmia. Hasta la fecha se han utilizado varias modalidades entre las que se incluyen la radiofrecuencia y la crioablación. Los principios de la criobiología se establecieron por primera vez con investigaciones sobre la congelación de los tumores y datos actuales sugieren que es necesaria una temperatura entre -30 a -40 °C para inducir muerte celular, ya sea por mecanismos inmediatos, como ruptura celular, lesión hipotérmica o daño vascular, o tardíos, como apoptosis. Se presenta el primer caso en Colombia de mapeo de alta densidad y crioablación como estrategias combinadas para el tratamiento efectivo de un paciente con alta carga de arritmia ventricular sintomática originada en el músculo papilar anterolateral, sin recurrencia de la arritmia en el tiempo de seguimiento.

Abstract Catheter ablation has become a practical approach for the treatment of cardiac arrhythmias, especially when optimal pharmacological management does not achieve adequate control of it, thus reducing hospital readmission and improving quality of life, even in patients in whom the complete resolution of the arrhythmia is not achieved. To date, a variety of modalities have been used, including radiofrequency and cryoablation. The principles of cryobiology were established for the first time with research on the freezing of tumors and current data suggest that a temperature of -30 to -40 °C is necessary to induce cell death either by immediate or delayed mechanisms; immediate as cellular rupture or hypothermic injury as well as vascular damage or apoptosis among the late. The first case in Colombia of high-density mapping and cryoablation is presented as combined strategies for the effective treatment of a patient with a high load of symptomatic ventricular arrhythmia originating in the anterolateral papillary muscle, without recurrence of the arrhythmia at the time of follow-up with symptoms, so it was to successful cryoablation, as the first case with this technique.

Anterolateral papillary muscle rupture after intervention of the right coronary artery.

Rupture of the anterolateral papillary muscle following a right coronary artery occlusion is extremely rare, and when complicated by a right ventricular infarction, can be fatal. The literature on optimal management of this complication is limited. We present an unusual case of anterolateral papillary muscle rupture following intervention of the right coronary artery.

Características morfológicas y biométricas del músculo papilar septal en corazones de individuos chilenos / Morphological and biometric characteristics of septal papillary muscle in hearts of chilean individuals

Se realizó un estudio descriptivo de las características anatómicas y biométricas del músculo papilar septal en 30 corazones de individuos adultos chilenos, en edades comprendidas entre 18 y 84 años de edad, de ambos sexos, sin aparente patología cardíaca, pertenecientes a la Unidad de Anatomía Humana Normal del Departamento de Ciencias Básicas de la Universidad de La Frontera. Los resultados mostraron que el músculo papilar septal, se presenta en un 83,3 por ciento de los corazones del estudio. De éstos, el 44,0 por ciento presenta un solo músculo, el 28 por ciento presenta dos músculos y el 28 por ciento tres músculos papilares septales. De los músculos papilares septales encontrados, el 71,1 por ciento correspondió a la forma cono libre, el 24,4 por ciento a la forma cono pegado y el 4,5 por ciento a la forma puente. En cuanto a la longitud de forma cono pegado y cono libre, el rango que se encuentra en mayor porcentaje está entre 4,0 mm ­ 5,99 mm; con un 45,5 por ciento y 42,4 por ciento, respectivamente. Este estudio nos demuestra la importancia de incorporar al músculo papilar septal a la nomenclatura anatómica internacional.

A descriptive research study was carried out on the anatomical and biometric characteristics of the septal papillary muscle in 30 hearts of adult Chilean subjects, between 18 and 84 years of age of both sexes and without apparent cardiac pathology, from the Normal Human Anatomy Unit, Basic Sciences Department of the Universidad de La Frontera. Results show that the septal papillary muscle was present in 83.3 percent of the hearts in the study. Of these 44.0 percent show one muscle only, 28 percent show two muscles and 28 percent show three septal papillary muscles. In the septal papillary muscles found, 71.1 percent are free cone-shaped, 24.4 percent were attached cone-shaped, and 4.5 percent were bridge-shaped. Regarding the length of attached cone and free cone shaped, the highest percentage range was between 4.0 mm and 5.99 mm, with 45.5 percent and 42.4 percent respectively. The present study shows the importance of integrating the septal papillary muscle to the International Anatomical Nomenclature.

Actividad rítmica del músculo papilar inducida por estimulación de alta frecuencia: ritmos n:1, formas de transición e histéresis / Arrhytmic actiitty of the papilary muscle induced by high frecuency stimulatiion: rhythm n:1, transition forms and hysteresis

Los tejidos cardíacos son capaces de trabajar en un amplio intervalo de frecuencias con el fin de atender las distintas demandas que el organismo impone al sistema cardiovascular. Sin embargo, bajo un régimen de cambios de frecuencia y con ciertas condiciones patológicas, pueden desarrollarse arritmias, como bloqueos, taquicardias, fibrilaciones, etc. de posibles consecuencias fatales. Esto motiva la realización de diversos arreglos experimentales en los cuales se explora el comportamiento del corazón, o de regiones de éste. En este artículo reportamos diversos fenómenos que ocurren en el músculo papilar de cobayo cuando se le estimula eléctricamente, desde una frecuencia basal de un pulso por segundo (pps) hasta frecuencias muy altas, de varias decenas de pps, pero incrementando paulatinamente la frecuencia de estimulación. Describimos que en nuestras condiciones experimentales, el músculo despliega sucesivamente ritmos tipo n:1 (una respuesta cada n estímulos) con n creciente; encontramos también que entre uno y otro de estos ritmos aparecen diversas formas de transición, entre las cuales describimos una totalmente nueva en este sistema, que hemos denominado por "ráfagas"; finalmente mostramos que este sistema exhibe de manera generalizada histéresis en la frecuencia, siendo el primer reporte que se hace para esta especie y además el primer reporte en el que se muestran varias "asas" o regiones de histéresis por frecuencia dentro de una misma excursión experimental. Debido al gran volumen de datos generados, hemos introducido una forma de presentación y análisis concisa y eficiente, basada en los espectros de potencia de los datos obtenidos a través de la transformada rápida de Fourier. Este método también se describe brevemente en el artículo.

Cardiac tissues are able to work within a wide range of frequencies to respond to the changing requirements an organism may have. However, during these frequency variations and under certain pathologic conditions arrhythmias such as blocks, tachycardia, fibrillation, etc, may arise some with fatal consequences. For this reason several experimental procedures have been developed that have shown to be useful in studying whole heart properties, or as an alternative from portions of it when changes in its work rate are imposed. This study reports different phenomena occurring in the papillary muscle of the guinea pig heart when stimulated at very high frequency, of several tens of pps, while analyzing its responses during gradual increments starting at 1 (pulses per second). We found that in our conditions papillary muscles display N:1 rhythms with progressive higher N; further more we found that between one and the next rhythm diverse transition patterns appear, among them a new one that we have named "burst pattern". Finally we show that our system exhibits a generalized process of hysteresis by frequency, being this the first report for guinea pig cardiac tissue and the first one to show also the presence of several hysteresis loops in the same experiment. Due to the large volume of generated data we used a faster and easier way to analyze and display them, based on the fast Fourier transform (FFT). The method is briefly described. (Arch Cardiol Mex 2004; 74:11-24).

Influência da pós-carga sobre a taxa de variação da tensão desenvolvida (dT/dt). Estudo em músculo cardíaco isolado / Effects of afterlood on peak rate of tension rise (dT/dt). Study in isolated cardiac muscles

PURPOSE: To evaluate the effects of afterload on peak rate of tension rise (dT/dt) in the isolated muscle. METHODS: Left ventricular papillary muscles from Wistar rats were studied in isometric and isotonic afterloaded contractions. Muscles were analised in Krebs-Henseleit solution with calcium concentration of 2.52mM at 28 degrees C. The resting muscle length (preload) was maintained constant. The peak isometric developed tension (DT) and dT/dt were measured during increases of afterload (25, 50, 75 and 100 from DT). RESULTS: A rise in afterload corresponding to 50, 75 and 100 of DT, did not cause an increase in dT/dt values (p > 0.05). The dT/dt value decreased (p < 0.05) when afterload was changed from 75 to 25 of DT. CONCLUSION: The data suggest that an increase in the afterload from 50 of the DT did not promote changes in the dT/dt

Objetivo - Avaliar a influência da pós-carga sobre a taxa de variação da tensão desenvolvida (dT/dt) em músculo isolado.Métodos - Músculos papilares isolados de ventrículo esquerdo de ratos Wistar foram estudados em contrações isométrica e isotônicas contra pós-carga, em solução de Krebs-Henseleit, com concentração de cálcio de 2,52mM, frequência de estímulos de 0,2Hz e temperatura de 28o C. O comprimento diastólico da fibra (pré-carga) foi mantido constante. A tensão máxima desenvolvida (TD) e dT/dt foram medidas durante elevações progressivas da pós-carga (25, 50, 75 e 100% da TD). Resultados - Não ocorreu variação significante (p> 0,05) na dT/dt entre as alterações de pós-carga correspondentes a 50, 75 e 100% da tensão máxima desenvolvida. O valor da dT/dt foi significantemente menor (p < 0,05) em pós-carga de 25%, comparativamente à de 75% da TD. Conclusão - Os resultados sugerem que elevações isoladas da pós-carga, a partir de 50% da tensão máxima desenvolvida, não acarretam variações nos valores da dT/dt.