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Restrictive Cardiomyopathy - Feline Cardiomyopathies (view source)
Revision as of 16:31, 2 December 2012
, 16:31, 2 December 2012→Echocardiography
This is the diagnostic test of choice for identification of RCM and excluding other cardiomyopathies.
This is the diagnostic test of choice for identification of RCM and excluding other cardiomyopathies.
Two-dimensional (2D) and M-mode imaging may reveal pronounced dilation of one or both atria and normal diameter and thickness of the ventricular chambers. Within the left atrium it is often possible to identify areas of spontaneous echo-contrast, reflecting blood stasis, or thrombi. The left atrium and the left auricular appendage should be carefully examined for this reason. It is useful to measure left auricular appendage flow velocity. Even in the absence of thrombi, evidence suggests that if velocity is <0.2 m/s on pulsed wave Doppler, the cat is at risk of thromboembolic complications.
'''Two-dimensional (2D) and M-mode''' imaging may reveal pronounced dilation of one or both atria and normal diameter and thickness of the ventricular chambers. Within the left atrium it is often possible to identify areas of spontaneous echo-contrast, reflecting blood stasis, or thrombi. The left atrium and the left auricular appendage should be carefully examined for this reason. It is useful to measure left auricular appendage flow velocity. Even in the absence of thrombi, evidence suggests that if velocity is <0.2 m/s on pulsed wave Doppler, the cat is at risk of thromboembolic complications.
====Endomyocardial form of Restrictive Cardiomyopathy (eRCM)====
====Endomyocardial form of Restrictive Cardiomyopathy (eRCM)====
====Myocardial form of Restrictive Cardiomyopathy (mRCM)====
====Myocardial form of Restrictive Cardiomyopathy (mRCM)====
In this form of RCM, the left ventricle appears normal, but there is concurrent left atrial or biatrial enlargement.
In this form of RCM, the left ventricle appears normal, but there is concurrent left atrial or biatrial enlargement.
'''Doppler echocardiography''' is important to assess diastolic function. Mitral inflow and pulmonary venous inflow should be assessed from a left apical 4 chamber view.
====Mitral Inflow====
Mitral inflow is assessed by positioning the pulse wave Doppler sample volume between the tips of the open mitral valve leaflets. In the normal animal this demonstrates two phases:
*E wave (Early filling) which is a consequence of active relaxation of the left ventricle, and the pressure gradient between the left atrium and left ventricle.
*A wave (Atrial contraction) which corresponds to the P wave of the electrocardiogram (ECG).
This may be difficult to assess in cats, especially those with tachycardia, as the two waves may summate at fast heart rates. When the two separate phases can be identified, evidence of a restrictive filling pattern includes:
*E wave has a high velocity, but short deceleration time (DT). The E wave velocity is high due to high LA pressure. The poor compliance of the LV causes an abrupt deceleration of blood flow.
*A wave velocity is very low as a result of poor atrial function and poor compliance of the left ventrical. Therefore the LA is not able to contribute much to LV filling.
The E/A ratio is an index used to estimate diastolic function, an E/A >2 confirms a restrictive filling pattern and diastolic dysfunction.
====Pulmonary Venous Inflow====
==Treatment==
==Treatment==
==Prognosis==
==Prognosis==