An improved method for detecting and quantifying cardiac muscle disarray in hypertrophic cardiomyopathy

Area of Science:

• Cardiovascular Pathology
• Histology
• Biomedical Optics

Background:

• Muscle disarray is a known characteristic of hypertrophic cardiomyopathy (HC).
• Previous assessments of cellular disorganization in HC have been semiquantitative.
• A need exists for precise, quantitative methods to evaluate myocardial architecture in HC.

Purpose of the Study:

• To describe and validate a quantitative method using polarized light microscopy for assessing cellular disorganization in hypertrophic cardiomyopathy.
• To compare the quantitative cellular orientation in hypertrophic cardiomyopathy (HC) hearts with normal hearts.
• To determine if polarized light microscopy can detect disorganization in areas of HC septa that appear normal grossly.

Main Methods:

• Examined hematoxylin and eosin-stained ventricular septa from six HC patients and six normal individuals.
• Measured cell orientations in five regions per section using a polarizing microscope with a rotating stage.
• Calculated mean and angular deviation of cell orientation angles and plotted histograms.

Main Results:

• Normal hearts exhibited predominantly parallel cell alignment with sharply peaked orientation distributions (4-13 degrees angular deviation).
• Hypertrophic cardiomyopathy (HC) hearts lacked sharp peaks, showing wider angular deviations (7-37 degrees) and sometimes bimodal distributions.
• Abnormal cellular orientation distributions were detected in HC septa, even in grossly normal-appearing areas.

Conclusions:

• Polarized light microscopy offers an improved, quantitative method for detecting and quantifying cellular disorganization in hypertrophic cardiomyopathy (HC).
• This technique provides a more objective assessment of myocardial architecture compared to semiquantitative methods.
• Quantitative analysis of cellular orientation can identify structural abnormalities in HC not apparent through gross inspection.