Step2: Risk Assessment

• Acute Exercise Stress:

  • causes increase in sympathetic activity + decrease in vagal stimulation -> increase in heart rate and systolic blood pressure -> increase in myocardial volume oxygen (MVO2) and so coronary heart disease -> increase in ischaemia -> altered conduction velocity + altered depolarisation/repolarisation -> increase in ventricular ectopic
  • causes sodium/potassium imbalance -> increase in myocardial irritability -> ventricular ectopic activity
  • causes increase in catecholamines -> increase in myocardial irritability -> ventricular ectopic activity

  
• Immediate Post Exercise:

  • abrupt cessation of activity -> decrease in venous return -> decrease in cardiac output -> decrease in blood pressure -> coronary perfusion -> increase in ischaemia -> altered conduction velocity + altered depolarisation/repolarisation -> increase in ventricular ectopic
  • causes arterial vasodilation -> decrease in blood pressure -> coronary perfusion -> increase in ischaemia ->altered conduction velocity + altered depolarisation/repolarisation -> increase in ventricular ectopic
• • need to sufficiently vasodilate arteries during a warm up, so that during moderate intensity, the supply and demand is matched, therefore not risking ischaemia - need a 15 minute warm up
  • need a 10 minute cool down to bring down levels of catecholamines in blood flow and restore venous return to bring heart rate down, to once again match supply and demand to reduce risk of ischaemia
  • the idea of matching supply and demand is also why active recovery is recommended between exercises in a circuit
• Is cardiac rehab safe:

  • cardiac rehabilitation:
  • one nonfatal cardiac complication per 752,365 pt hours of exercise participation (Franklin 1998)
  • average 20 hours per patient, 500 pts per year = 1 event every 75 years
  • one fatal event for every 219,970 pt hours of exercise participation
  • exercise testing:
  • four non-fatal complications per 10,000 (Fletcher et al 2001)
• The context for greater risk during exercise:

  • least physically active people (sedentary)
  • those with lower levels of fitness (< 5 METs)
  • highly emotive activities (overly competitive)
  • intense start to exercise
  • unaccustomed to the mode of physical activity (novices)
  • high relative exercise intensity (blood pressure, heart rate or rate pressure product)
  • sudden cessation of exercise
• Risk Stratification Chart:

  • bottom 2 = low risk
  • middle 2 = moderate risk
  • top 2 = high risk
  • level of risk is an indicator for level of intensity pt should be working at, level of supervision pts require and how quickly they should be progressed