Heart Rate Variability and Exercise Testing

Normal sinus rhythm has a variability of...

<0.12 seconds

Sinus Arrhythmia has a variability of...

>0.12 seconds

How does the PNS and SNS interact to increase and decrease HR? and what is HR recovery dependent on?

PNS - facilitates HR

SNS - suppresses PNS or increases PNS

- HR recover is dependent on PNS reactivation and SNS withdrawal

Does HR variability increase or decrease with age?

decreases (body less resilient to challenge and change)

How can we improve HRV?

- routine exercise and healthy diet

- manage stress

(high variability reflects adaptability of the body)

Is HRV higher or lower with increased parasympathetic activation? why?

HRV is higher

sympathetic activation impairs HR regulator (vagus)

As HR increases what happens to HRV?

HRV decreases

What exercises are included in the formal exercise testing?

1. walking steps

2. stationary bike

3. arm or wheelchair ergometry

4. treadmill

5. 6 minute walk test

What are the common indications for formal exercise testing?

- chest pain suggestive of coronary disease

- evaluate effects of surgery or medical intervention

- evaluate hypertension with activity

- find functional capacity

What is endurance exercise testing used for?

predict VO2 and diagnose exercise intolerance

What classifies an endurance exercise test as maximal test? length, goal, end result?

RPE and respiratory exchange ratio (RER) will steadily increase

- 10-20 minutes

- goal: increasing intensity

- end of test represents max a body can produce

What classifies an endurance exercise test as submax test? length, goal, end result?

RPE and respiratory exchange ratio (RER) will plateau

- 30+ minutes

- goal: steady state (85% of HRmax, if HR increases, intensity will be reduced

- end of test represents % of max a body can produce

When is low level endurance testing performed?

after MI or CABG sometimes as early as 3-4 days after (5 minute walk test or gait speed test)

What are the contraindications to low level testing?

- unstable angina

- severe heart failure

- serious arrhythmias at rest

- 2nd or 3rd degree heart block

- valvular disease

- blood pressure >180/105

- patient refusal

What is the gold standard exercise test?

max

Who is at highest risk for cardiac event during testing?

pt with

- reduced systolic BP

- reduce HR

- angina

- frequent arrythmias

What is the criteria for terminating a max exercise test? theres a lot I only listed a few...

- sustained ventricular tachycardia

- 2nd or 3rd degree heart block

- rapid arrhythmias

- hypotensive blood pressure >20 drop

- extreme shortness of breath

- severe ST segment depression

- dizziness

- blood pressure >250/>115 or both

What is the criteria for terminating a low/submax exercise test?

- 70-75% of age predicted maximal heart rate achieved

- max heart rate 120-130

- ST segment depression

- claudication pain

- dizziness

- decrease in systolic blood pressure 10-15

- hypertensive blood pressure >200/>110

- level 1 out of 4 angina

What are the relative contraindications for exercise testing?

- moderate or severe aortic stenosis

- left main coronary artery disease

- severe hypertension >200/>110 either or both

- acquired advanced or complete heart block

What are the absolute contraindications for exercise testing?

- recent MI

- acute pericarditis or myocarditis

- unstable angina

- rapid arrhythmias

- untreated 2nd or 3rd degree heart block

- Overt congestive heart failure

- acute illness

When are tests stopped on a normal exercise test?

workload reaches certain protocol or 85% age predicted max heart rate is reached

What is the bruce treadmill protocol and what does it find?

- can calculate functional aerobic impairment

- starting speed 1.7mph with average test taking 6-12 minutes

What is considered a positive exercise testing?

>1 mm horizontal or down-sloping ST-segment depression

What is considered an equivocal exercise testing?

>0.5 but <1.0 mm horizontal or downsloping ST-segment depression or more than 1.5 mm upsloping depression

What is considered a negative exercise testing?

<0.5mm horizontal or downsloping ST-segment depression 87

What does ST segment depression early in an exercise test indicate?

more severe coronary blockage

What is the difference in peak HR and HR after 1 minute?

heart rate recovery

What measureds volume of expired air and concentraion of O2 and CO2 in expired air?

ventilatory gas analysis

What is the adenosine and dipyridamole walk protocol?

low level treadmill exercise while reducing adverse effects (drugs) to increase diagnostic accuracy

What is ergonovine stimulation?

use of ergonovine to cause spasm if narrowing is present which is then relieved by vasodilators

What are the absolute contraindications to pharmacological stress testing?

- active brochospasm

- 2nd or 3rd degree heart block

- systolic blood pressure <90

- patient on dipyridamole or methylxanthines

What are the relative contraindications to pharmacological stress testing?

- history of airway disease

- history of sick sinus syndrome

Describe the order of an evaluation for exercise safety? 5 items

1. establish safety for exercise participation

2. receive MD referral

3. physical exam

4. measure resting ECG, HR, BP, pulse Ox, PFT

5. functional mobility

What is the cutoff value of hemoglobin when not to perform out of bed activities?

8g

Is medical clearance recommended, not necessary, or necessary? pt does not exercise and has no signs of CV, metabolic or renal disease

not necessary

Is medical clearance recommended, not necessary, medical clearance necessary? pt does not exercise and has known CV, metabolic or renal disease and asymptomatic

clearance recommended

Is medical clearance recommended, not necessary, medical clearance necessary? pt does not exercise and has symptoms suggestive of CV, metabolic or renal disease

clearance recommended

Is medical clearance recommended, not necessary, medical clearance necessary? pt exercises regularly and has no CV, metabolic or renal disease

not necessary

Is medical clearance recommended, not necessary, medical clearance necessary? pt exercises regularly and has known CV, metabolic, or renal disease and asymptomatic

not necessary for moderate intensity exercise however recommended for vigorous exercise

Is medical clearance recommended, not necessary, medical clearance necessary? pt exercises regularly and has signs suggestive of CV, Metabolic or renal disease

Stop exercise and medical clearance is necessary