Structural changes

A globular, enlarged heart on the chest radiograph is commonly seen in many types of heart failure. In such a patient the left ventricular cavity is enlarged and becomes more spherical. This is termed ventricular remodelling.

There are two main consequences of left ventricular remodelling:

• intramural tension increases:
  • in the normal heart this would increase myocardial contractility according to the Starling law
  • in the failing heart the increased oxygen consumption may exacerbate myocardial ischaemia
    
    
• impaired haemodynamics:
  • in the normal heart, the period of isovolumic contraction at the beginning of systole redistributes blood towards the outflow tract
  • in the remodelled ventricle this redistribution is lost and pumping efficiency is reduced

Left ventricular dilatation is an adverse prognostic sign.

Ventricular remodelling following myocardial infarction may be inhibited by ACE inhibition.

Note that left ventricular dilatation is not a feature of heart failure due to:

• restrictive or constrictive cardiomyopathies
• other causes of diastolic dysfunction