Hypertrophic Cardiomyopathy

Shemy Carasso, Lynne Williams, Manhal Habib, Harry Rakowski

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

Abstract

In hypertrophic cardiomyopathy (HCM), macroscopic and microscopic alterations in myocardial structure (myocardial hypertrophy, fiber disarray, increased loose connective tissue, and fibrosis) and abnormalities of the coronary microvasculature interfere with both myocyte force generation and myocardial relaxation. The mutations related to HCM result in the production of abnormal myocardial sarcomeric proteins that have altered contraction and relaxation characteristics. These include changes in the affinity between the various contractile proteins, changes in the sensitivity to Ca+2, the efficiency of energy utilization (from ATP), and its expenditure. During stress, ischemia-induced diastolic dysfunction occurs at higher heart rates, reducing the diastolic filling period, resulting in increased intracavitary pressures aggravating subendocardial ischemia further. This is compounded by reduced left ventricular (LV) diastolic distensibility during exercise. Dyspnea is a common symptom, predominantly related to the presence of diastolic dysfunction and LV outflow tract (LVOT) obstruction. Worsening dyspnea may be precipitated by either the acute onset of atrial fibrillation or more insidiously by the development of LV systolic dysfunction. Echocardiography is the imaging modality of choice for the assessment of diastolic function in HCM, although accurate classification of diastolic function grade presents a challenge due to the compounding effects of LVOT obstruction and mitral regurgitation. Myocardial mechanics (assessment of strain rate, apical reverse rotation, and left atrial phasic volumes) may aid in diastolic functional assessment and be correlated with symptoms. Medical and invasive (septal reduction) therapy of LVOT obstruction may also improve diastolic function in patients with obstructive HCM.

Original languageEnglish
Title of host publicationDiastology
Subtitle of host publicationClinical Approach to Heart Failure with Preserved Ejection Fraction
PublisherElsevier
Pages322-333
Number of pages12
ISBN (Electronic)9780323640671
DOIs
StatePublished - 1 Jan 2020

Bibliographical note

Publisher Copyright:
© 2021 Elsevier Inc. All rights reserved.

Keywords

  • Fiber disarray
  • Fibrosis
  • Increased loose connective tissue
  • Left atrial volumes
  • Mutations of sarcomeric proteins
  • Myocardial hypertrophy
  • Myocardial mechanics
  • Strain

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