Examination of the Heart in Cardiomyopathy

The short-axis sectioning (bread loafing) method described above serves well for the examination of the cardiomyopathic heart. Cardiac hypertrophy and dilation may be demonstrated quite effectively by this method. If the left ventricular cavity measures >4 cm, excluding the papillary muscles, it is considered that the patient was in congestive heart failure prior to death even if there is no history to corroborate the autopsy findings. Left ventricular hypertrophy is said to be present if the LV wall measures >1.5 cm. On the other hand, if the left ventricular wall measures <1.5 cm but the heart weight is increased and the left ventricular cavity is enlarged, then there will be microscopic appreciation of myocyte hypertrophy.

Histologic examination of the myocardium is critical to determining the cause of the cardiomyopathy. Thus, in addition to sections of tissue with obvious gross pathology, samples of the walls of all four cardiac chambers, the septum, and papillary muscles should be taken. In the past, the right ventricle has been relatively ignored, but because of the greater awareness of right ventricular infarction and right ventricular dysplasia/cardiomyopathy, it should be a routine to examine the right ventricle carefully. For establishing the diagnosis of right ventricular cardiomyopathy, the most helpful single observation to make is one of fibrosis or scarring in the right ventricular wall with intermingling of fat; these lesions are most often seen in the inflow region of the right ventricle on the posterior wall or in the anterior wall of the right ventricular outflow tract. These lesions can be commonly appreciated grossly if a careful examination of the heart is carried out.

The heart also may be cut in four chamber view by cutting the heart from the apex to base, along the acute margin of the right ventricle and the obtuse margin of the left ventricle and continuing the plane of section through the atria (Figure 2.2.1.6). This four chamber view is best for evaluating the atrial and ventricular chamber size. In cases of hypertrophic cardiomy-opathy, the heart should be cut in the long axis view of the left ventricular outflow tract. The plane of dissection of the aortic valve leaflet is through the right coronary and the posterior non-coronary leaflets, the anterior and the posterior mitral leaflets, the posterior and the anterior left atrial wall, ventricular septum, posterolateral wall of LV and the anterior right ventricular wall (Figure 2.2.1.7). Sections to determine the presence of fibromuscular disarray are taken in the transverse plane, usually from the septal location with the largest dimension.

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