Myocardial Ultrasonic Backscatter in Hypertension

Abstract

Abstract-A disproportionate accumulation of fibrillar collagen is a characteristic feature of hypertensive heart disease, but the extent of myocardial fibrosis may differ in different models of hypertension. In experimental studies, aldosterone and endothelins emerge as important determinants of myocardial fibrosis. Changes in myocardial extracellular matrix and collagen deposition can be estimated noninvasively by analysis of the ultrasonic backscatter signal, which arises from tissue heterogeneity within the myocardium and describes myocardial texture. This study was designed to investigate the relations between myocardial integrated backscatter and circulating aldosterone and immunoreactive endothelin in human hypertension. The study population consisted of 56 subjects: 14 healthy normotensive volunteers and 42 hypertensive patients (14 with primary aldosteronism, 7 with renovascular hypertension, and 21 with essential hypertension). The patients with essential and secondary hypertension were matched for age, gender, body mass index, and blood pressure. Myocardial integrated backscatter at diastole was 19.8Ϯ2.0 and 20.8Ϯ2.9 decibels in normotensive control subjects and patients with essential hypertension and significantly higher in patients with primary aldosteronism (27.4Ϯ3.8 decibels, PϽ0.01) and renovascular hypertension (26.8Ϯ4.8 decibels, PϽ0.01). In the population as a whole, as well as in the hypertensive subpopulation, myocardial integrated backscatter was directly related to plasma aldosterone (rϭ0.73 and 0.71, PϽ0.01 for both) and immunoreactive endothelin (rϭ0.60 and 0.56, PϽ0.01 for both). The data of this study suggest that in human hypertension, circulating aldosterone and immunoreactive endothelin may induce alterations in left ventricular myocardial texture, possibly related to increased myocardial collagen content.

Left ventricle remodeling in men with moderate to severe volume-dependent hypertension

“…168 ± 25 a unknown unknown NO NS Kozakova et al 35 14 (64%) 163 ± 4 a 4 ± 3 known YES Concentric remodeling Matsumura et al 8 25 ( …”

Long-Term Effect of Spironolactone on Cardiac Structure as Assessed by Analysis of Ultrasonic Radio-Frequency Signals in Patients With Ventricular Hypertrophy

“…5 Integrated ultrasonic backscatter is a simple and widely used parameter for myocardial tissue characterization, [6][7][8][9][10] and we reported a significant correlation between myocardial integrated backscatter and LV fibrosis. 11 However, serious problems regarding standardization limit its use.…”

Assessment of Myocardial Fibrosis in Hypertrophic Cardiomyopathy by Cardiac Magnetic Resonance: Modalities and Clinical Applications

“…Myocardial fibrosis could represent a substrate for the generation of malignant ventricular tachyarrhythmias, which is the current pathway for sudden cardiac death in HCM [5]. In an autopsy study in patients with HCM who died suddenly, the calculated interstitial collagen volume fraction was about 8 times greater than in control subjects and 3 times higher than in patients with essential hypertension [6], a condition well known to have interstitial fibrosis [7,8]. Fibrosis comprised 15% (up to 27%) of the transmural septal tissue sections [6].…”

“…In HCM there is an increase in the fraction of interstitial collagen, caused by the excessive synthesis of collagen I (increase of peptides released during the synthesis) not sufficiently balanced by its greater degradation for the reduced activity of metallo-proteinase catabolic (or collagenase) 1 and 2 of the matrix (MMP-1 and MMP-2) [9]. The accumulation of collagen, increasing the rigidity of left ventricle, is responsible for passive diastolic dysfunction, that is the leading cause of dyspnea [7,8,10]. In animal models with genetic mutations responsible for human HCM, it has been shown that treatment with an AT1 receptor antagonist, [11] or with simvastatin, [11] or more recently with N-acetylcysteine, [12] a precursor of glutathione, reduces the hypertrophy, the fibrosis, disarray and improves diastolic function.…”