In hypertrophy the heart muscle
is thicker. This can have different causes. Left ventricular hypertrophy results from an increase in left ventricular workload, e.g. during hypertension or aortic valve stenosis. Right ventricular hypertrophy results from an increase in right ventricular workoad, e.g. emphysema or pulmonary embolisation. These causes are fundamentally different from [[Miscellaneous#Hypertrophic_Obstructive_Cardiomyopathy|hypertrophic obstructive cardiomyopathy (HCM)]], which is a congenital misallignment of cardiomyocytes resulting in hypertrophy.
Left and right ventricular hypertrophy can be distinguished on the ECG:
As the left ventricular becomes thicker, the QRS complexes become larger. This is especially true for leads V1-V6. The S wave in V1 is deep, the R wave in V4 is high. Often some ST depression can be seen in leads V5-V6, which is in this setting is called a 'strain pattern'.
To diagnose left ventricular hypertrhophy on the ECG one of the following criteria should be met:
==Right ventricular hypertrophy==
hypertrohpy, the R wave is greater than the S wave in V1]]
Right ventricular hypertrophy occurs mainly in lung disease or in congenital heart disease.
The ECG shows a negative QRS complex in I (and thus a right [[heart axis]]) and a positive QRS complex in V1.
;Criteria for left atrial voor left atrial enlargement. Either
:P wave with a broad (>0,04 sec or 1 small square) and deeply negative (>1 mm) terminal part in V1
:P wave duration >0,12 sec in
laeds I and / or IILeft atrial enlargement is often seen in mitral valve insufficiency, resulting in backflow of blood from the left ventricle to the left atrium and subsequent incresed local pressure.
:P >2,5 mm in II / III and / or aVF
:P >1,5 mm in V1.
Right atrial enlargement can result from increased pressure in the pulmonary artery, e.g. after pulmonary
embolisation. A positive part of the biphasic p-wave in lead V1 larger than the negative part indicates right atrial enlargement. The width of the p wave does not change.
:Biphasic p wave in V1 of more than 0.04 sec duration. The positive initial part is > 1.5mm and the negative terminal part > 1mm
In biatrial enlargement
is the ECG whos signs of both left and right atrial enlargement. In V1 the p wave has large peaks first in positive and later in negative direction.
#Sokolow Sokolow M, Lyon TP: ''The ventricular complex in left
verntricular hypterfophy as obtained by unipolar precordial and limb leads.'' Am Heart J 37: 161, 1949