Conditions That Displace the Point of Maximal Impulse (PMI)
Lateral displacement of the PMI beyond the mid-clavicular line indicates left ventricular enlargement from conditions such as dilated cardiomyopathy, left ventricular hypertrophy, or chronic volume overload states. 1
Left Ventricular Enlargement Conditions
The most common causes of PMI displacement are conditions that enlarge the left ventricle:
Left ventricular hypertrophy from chronic pressure overload (such as hypertension or aortic stenosis) displaces the PMI laterally and may create a sustained, forceful impulse 1
Dilated cardiomyopathy causes lateral displacement of the PMI as the left ventricle enlarges and the apex shifts leftward 1
Chronic volume overload states including chronic aortic regurgitation and chronic mitral regurgitation lead to progressive left ventricular dilation with lateral PMI displacement 1
Hyperkinetic States
Certain hyperdynamic conditions alter the PMI character and may affect its location:
Hyperdynamic states such as anemia, thyrotoxicosis, and acute aortic regurgitation produce a hyperactive (hyperdynamic) apical impulse that may be more prominent and displaced 1
In acute severe mitral regurgitation, the precordial impulse may be misleading as a normal-sized left ventricle does not produce a hyperdynamic apical impulse despite the severity of the condition 1
Structural Cardiac Abnormalities
Specific structural heart diseases create characteristic PMI patterns:
Hypertrophic cardiomyopathy may produce a double or bifid apical impulse, which can be appreciated on palpation 1
Right ventricular hypertrophy or enlargement causes a parasternal heave/lift rather than displacing the apical PMI, though it may alter the overall precordial examination 1
Takotsubo cardiomyopathy produces apical ballooning with an abnormal apical impulse characterized by hypokinesis of mid and apical segments 1
Important Clinical Caveats
Several factors can obscure or confound PMI assessment:
Obesity, emphysema, or thick chest walls may obscure the apical impulse even when significant cardiac enlargement is present, making displacement difficult to detect clinically 1
The normal PMI location is at the 5th intercostal space inside the mid-clavicular line, but this is subject to great individual variation 2, 1
When performing echocardiography, the probe should be placed at the PMI as determined by physical exam to obtain the apical four-chamber view, recognizing that this location varies considerably between individuals 2