Evidence for Microvascular Dysfunction in Hypertrophic Cardiomyopathy

Abstract

Background-Microvascular dysfunction in hypertrophic cardiomyopathy (HCM) may create an ischemic substrate conducive to sudden death, but it remains unknown whether the extent of hypertrophy is associated with proportionally poorer perfusion reserve. In HCM patients, hMBF decreased with increasing end-diastolic wall thickness (PϽ0.005) and preferentially in the endocardial layer. The frequency of endocardial hMBF falling below epicardial hMBF rose with wall thickness (Pϭ0.045), as did the incidence of fibrosis (PϽ0.001). Conclusions-In HCM the vasodilator response is reduced, particularly in the endocardium, and in proportion to the magnitude of hypertrophy. Microvascular dysfunction and subsequent ischemia may be important components of the risk attributable to HCM.

The Clinical Value of Myocardial Blood Flow Measurement

“…Gadolinium chelates do not enter intact cell membranes and the volume of distribution is restricted to approximately 20% in normal viable myocardium (24). Different extravascular, extracellular contrast medium dose administration protocols and pulse sequences have been tested and validated in animal experiments (25)(26)(27), which have been subsequently translated into human studies (28)(29)(30)(31)(32)(33).…”

“…6) (76-78). In a recent paper by Petersen et al (31), the correlation between degree of hypertrophy, MBF at rest and during hyperemia (adenosine), and myocardial fibrosis was assessed using MRI in 35 patients with HCM. This study provided novel evidence that hyperemic MBF decreased with increasing end-diastolic wall thickness and preferentially in the subendocardial layers.…”

“…This study provided novel evidence that hyperemic MBF decreased with increasing end-diastolic wall thickness and preferentially in the subendocardial layers. The frequency with which subendocardial blood flow fell below subepicardial blood flow was directly proportional to wall thickness and the incidence of fibrosis assessed by gadolinium late enhancement (31). In another study of 18 patients with HCM, PET with H 2 15 O was used to measure subepicardial and subendocardial blood flow and MRI was used to determine LV mass and volumes; LV outflow tract gradient was measured at cardiac catheterization.…”

Current state of the art and future of myectomy

“…In addition, there is evidence that unrelieved LVOTO can result in adverse remodelling and myocardial fibrosis, which are associated with coronary dysfunction in HCM (14), as well as clinical deterioration resulting in "end stage HCM" (15,16). Asymptomatic patients with large gradients across LVOT could be at risk of developing irreversible ischemic myocardial damage.…”

Hypertrophic Cardiomyopathy: Genetic Alterations, Pathogenesis and Pathophysiology

“…Результаты исследований с применением пози-тронно-эмиссионной (ПЭТ) и магнитно-резонанс-ной томографии показали, что степень дисфункции микроциркуляторного русла у больных ГКМП явля-ется независимым прогностическим критерием раз-вития симптомов СН и смертности больных, а выяв-ленные нарушения могут за много лет предшество-вать клиническому ухудшению течения болезни [40,47]. В связи с этим, интересными представляются данные исследования P. Bravo et al (2012), в котором не обнаружено значимых корреляций между градиен-том давления в ВТЛЖ и глобальными параметрами ишемии миокарда, оцениваемых по значениям пер-фузии, пика миокардиального кровотока и миокар-диального резерва на основании результатов ПЭТ.…”