ABSTRACT
Introducción y objetivos: La variación en la relación presión/volumen telesistólica entre el reposo y el estrés máximo es un índice de contractilidad del ventrículo izquierdo independiente de la poscarga. Aún no está claro si depende del volumen telediastólico y hasta qué punto. El objetivo de este estudio es evaluar la dependencia de la variación de la relación presión/volumen telesistólica entre el reposo y estrés (Δ) y el volumen telediastólico en pacientes con ecocardiografía de estrés negativa y con todos los intervalos de función ventricular izquierda en reposo. Métodos: Analizamos los datos interpretables obtenidos de 891 pacientes (593 varones; 63 ± 12 años) con fracción de eyección del 47 ± 12%: 338 pacientes estaban sanos, prácticamente sanos o hipertensos; 229 tenían arteriopatía coronaria y 324, miocardiopatía dilatada isquémica o no isquémica. Se los estudió con ecocardiografía de estrés en ejercicio (n =172), dipiridamol (n = 482) o dobutamina (n = 237). La relación presión/volumen telesistólica se evaluó en reposo y en estrés máximo a partir de una medición bruta de la presión arterial sistólica mediante esfigmógrafo con manguito y el volumen telesistólico, por ecocardiografía bidimensional mediante el método de Simpson biplanar. Resultados: Los valores absolutos de la variación reposo-estrés en la relación presión/volumen telesistólica fueron más altos con ejercicio y dobutamina que con dipiridamol. En la población general, se observó relación inversa entre la relación presión/volumen telesistólica y el volumen telediastólico en reposo (r2 = 0,69; p < 0,001) y en estrés máximo (r2 = 0,56; p < 0,001), pero no se observó esta relación al considerar la variación reposo-estrés de la relación presión/volumen telesistólica (r2 = 0,13). Conclusiones: El volumen telediastólico ventricular izquierdo no afecta a la variación reposo-estrés de la relación presión/volumen telesistólica en ventrículos izquierdos normales o anómalos durante el estrés físico o farmacológico (AU)
Introduction and objectives: The variation between rest and peak stress end-systolic pressure-volume relation is an afterload-independent index of left ventricular contractility. Whether and to what extent it depends on end-diastolic volume remains unclear. The aim of this study was to assess the dependence of the delta rest-stress end-systolic pressure-volume relation on end-diastolic volume in patients with negative stress echo and all ranges of resting left ventricular function. Methods: We analyzed interpretable data obtained in 891 patients (593 men, age 63 ± 12 years) with ejection fraction 47% ± 12%: 338 were normal or near-normal or hypertensive; 229 patients had coronary artery disease; and 324 patients had ischemic or nonischemic dilated cardiomyopathy. They were studied with exercise (n = 172), dipyridamole (n = 482) or dobutamine (n = 237) stress echocardiography. The end-systolic pressure-volume relation was evaluated at rest and peak stress from raw measurement of systolic arterial pressure by cuff sphygmomanometer and end-systolic volume by biplane Simpson rule dimensional echocardiography. Results: Absolute values of delta rest-stress end-systolic pressure-volume relation were higher for exercise and dobutamine than for dipyridamole. In the overall population, an inverse relationship between end-systolic pressure-volume relation and end-diastolic volume was present at rest (r2 = 0.69, P < .001) and peak stress (r2 = 0.56, P < .001), but was absent if the delta rest-stress end-systolic pressure-volume relation was considered (r2 = 0.13). Conclusions: Left ventricular end-diastolic volume does not affect the rest-stress changes in end-systolic pressure-volume relation in either normal or abnormal left ventricles during physical or pharmacological stress (AU)
Subject(s)
Humans , Echocardiography, Stress/methods , Ventricular Dysfunction, Left , Cardiomyopathy, Dilated , Coronary Disease , Ventricular Function, Left/physiology , Organ Size/physiology , Diastole/physiology , Myocardial Contraction/physiologyABSTRACT
INTRODUCTION AND OBJECTIVES: The variation between rest and peak stress end-systolic pressure-volume relation is an afterload-independent index of left ventricular contractility. Whether and to what extent it depends on end-diastolic volume remains unclear. The aim of this study was to assess the dependence of the delta rest-stress end-systolic pressure-volume relation on end-diastolic volume in patients with negative stress echo and all ranges of resting left ventricular function. METHODS: We analyzed interpretable data obtained in 891 patients (593 men, age 63 ± 12 years) with ejection fraction 47% ± 12%: 338 were normal or near-normal or hypertensive; 229 patients had coronary artery disease; and 324 patients had ischemic or nonischemic dilated cardiomyopathy. They were studied with exercise (n = 172), dipyridamole (n = 482) or dobutamine (n = 237) stress echocardiography. The end-systolic pressure-volume relation was evaluated at rest and peak stress from raw measurement of systolic arterial pressure by cuff sphygmomanometer and end-systolic volume by biplane Simpson rule 2-dimensional echocardiography. RESULTS: Absolute values of delta rest-stress end-systolic pressure-volume relation were higher for exercise and dobutamine than for dipyridamole. In the overall population, an inverse relationship between end-systolic pressure-volume relation and end-diastolic volume was present at rest (r2 = 0.69, P < .001) and peak stress (r2 = 0.56, P < .001), but was absent if the delta rest-stress end-systolic pressure-volume relation was considered (r2 = 0.13). CONCLUSIONS: Left ventricular end-diastolic volume does not affect the rest-stress changes in end-systolic pressure-volume relation in either normal or abnormal left ventricles during physical or pharmacological stress.
Subject(s)
Blood Pressure/physiology , Echocardiography, Stress/methods , Heart Ventricles/physiopathology , Ventricular Dysfunction, Left/diagnosis , Ventricular Function, Left/physiology , Ventricular Pressure/physiology , Aged , Cardiomyopathy, Dilated/diagnosis , Cardiomyopathy, Dilated/physiopathology , Coronary Artery Disease/diagnosis , Coronary Artery Disease/physiopathology , Diastole , Exercise/physiology , Female , Follow-Up Studies , Heart Ventricles/diagnostic imaging , Humans , Hypertension/diagnosis , Hypertension/physiopathology , Male , Middle Aged , Organ Size , Retrospective Studies , Stroke Volume , Ventricular Dysfunction, Left/physiopathologyABSTRACT
Sphericalization of the left ventricular (LV) chamber shape in patients with mitral regurgitation (MR) contributes to increased LV wall stress and energy consumption. On the basis of previous observations, we hypothesized the existence of regional differences in the force-frequency relation (FFR) within the LV that may contribute to its shape. Accordingly, in the present study, we assessed regional variation in the FFR in patients undergoing surgery for chronic, nonischemic MR with class II-III heart failure symptoms and related our findings to the in vivo LV shape. FFRs (steady-state isometric twitches, 0.2-3.4 Hz, 37 degrees C) were evaluated in MR myocardium from the LV subepicardial free wall (MR-FW) and papillary muscle (MR-PM) and from the subepicardial free wall in coronary artery bypass graft patients with normal LV contraction patterns [nonfailing (NF)]. Ascending slope, optimal stimulation frequency, and maximal twitch tension of the FFR were depressed in MR-FW and MR-PM compared with NF (P < 0.05). FFR depression was greater in MR-PM than in MR-FW. Between 107 and 134 beats/min, twitch tension became weaker in MR-PM, whereas it increased in MR-FW. Elevation of intracellular cAMP with forskolin eliminated FFR depression in MR-FW but not in MR-PM. MR-PM also had a 35% lower myosin heavy chain content and slowed twitch kinetics. In MR patients, the echocardiographic end-diastolic LV shape (end-diastolic eccentricity index = long axis/short axis) correlated with the ratio of ascending FFR slopes such that the end-diastolic eccentricity index increased 10% per 15% increase in slope ratio (r = 0.88, P = 0.01). These regional differences in the frequency dependence of contractility between the free wall and papillary myocardium may contribute to changes in LV shape in MR as well as during exercise.
