left ventricular hypertrophy

 

Left Ventricular Hypertrophy (LVH) is an independent risk factor for sudden death in those with hypertension (a 3 fold increase) independent of the blood pressure level (Sheppard and Davies 1998; Hirsch and Adams 1993; Priori SG et al 2001)  

 

 Structural changes:

 

What causes these structural changes in hypertensives (Mayat and Hughes 2003)?

  • Increased pressure exerts increased load (LaPlace’s Law)
  • Increased tension results in increased wall tensile stress
  • Normalisation of stress achieved by either increasing wall thickness or reducing chamber diameter or both

  

Changes are dependent on:

 

What are the consequences of structural changes?

  • Impaired relaxation and thus a longer LV filling time, leaving more blood within the left atrium and increased atrial contraction force
  • Impaired diastolic function leads to reduced LV compliance and reduced LV end diastolic volume, in turn leading to a reduction in stroke volume and symptoms of low output, such as fatigue.
  • Intramyocardial blood flow is compromised, leading to myocardial fibrosis and electrical instability (myocardial fibrosis is seen in 30% of those hearts considered to be ‘abnormal’ in victims of sudden cardiac death)
  • Ventricular ectopic beats, increased QT interval and VT are amongst those electrical disturbances recorded in those with LVH

 

significance of  heart weight at autopsy

Researchers have suggested that hearts weighing >550g can reasonably be associated with an increased risk of sudden cardiac death, with the greatest risk being in those with systemic hypertension or aortic stenosis (Davies and Popple 1979).

Attempts have also been made to correlate heart weights with height and body weight, to provide some assistance to autopsy pathologists in determining ‘normal’ or ‘expected’ heart weights.

Fulton (1952) described the technique to be used to weigh ventricles individually - and thus attempt to gain an objective assessment of left and right ventricular hypertrophy - whilst values published by Hangartner et al (1985) and Kitzman et al (1988) can assist in correlating heart weight with body weight.

 

references

 

 

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