Ageing Heart

Question 1

Prevention -
Exercise has similar mortality benefits to drug interventions in the 2ndary prevention of CHD, rehab from stroke, treatment of heart failure and prevention of diabetes.

Answer 1

Fact

Question 2

Draw a diagram of cardiovascular physiology involving muscles, heart and lungs.

Answer 2

Pic

Question 3

Outline the Fick equation

Answer 3

VO2 = HR x SV x (CaO2 - CvO2)

Question 4

What Is VO2 a good indicator of?

Answer 4

CRF and the functional capacity of the CV system

Question 5

What factors may impact the functional capacity of the CV system?

Answer 5

HR - drugs, sinus node dysfunction,
SV - cardiomyopathies, conditioning, genetic factors,
CaO2 - Hb, PaO2, SaO2
CvO2 - skeletal muscle dysfunction, capillary density

Question 6

Define exercise tolerance

Answer 6

Level of physical exertion an individual may achieve prior to reaching a state of exhaustion

Question 7

Define exercise intolerance

Answer 7

A condition of inability or decreased ability to perform exercise

Question 8

What test can be used to evaluate exercise tolerance and functional ability of cardiac patients?

Answer 8

Cardiopulmonary exercise stress test, with gas exchange and harmony amid monitoring

Question 9

What can be determined from a cardiopulmonary exercise stress test?

Answer 9

VO2 max, anaerobic threshold, ventilation, HR and be response to exercise and recovery, RPE

Question 10

Why is it important to assess disease severity in cardiac patients?

Answer 10

To see whether they are capable/safe to do PA. 
Those with class 4 would be unable to do PA without severe discomfort and would have a reduced peak O2 consumption and anaerobic threshold.

Question 11

Follow ACSM guidelines for exercise testing and prescription

Answer 11

Fact

Question 12

What is the physiological basis for differences in VO2 max between athletes and normally active?

Answer 12

During max exercise, athletes typically have a lower HR and increased SV. The a-vo2 diff is equivocal. The increase in SV results in the greater Qmax and therefore VO2 max.

Question 13

What is the physiological basis for differences in VO2 max between normally active people and cardiac patients?

Answer 13

During max exercise, cardiac patients have a significantly lower SV and slightly lower HR. The a-vo2 diff is ~ equal. The huge drop in SV is the main contributor to lower Qmax and therefore VO2 max.

Question 14

Why is CO roughly equivocal at rest between athletes and normally active people?

Answer 14

Athletes have a lower resting HR but greater SV than normally active. These level out to ~ equal CO to normally active. Athletes heart is more efficient, more blood pumped per heartbeat, so needs to beat less.

Question 15

What factors regulate CO?

Answer 15

HR —> autonomic innervation (para + sympathetic NS), hormones (adrenaline, Ach), fitness level, age
SV —> heart size, fitness levels, gender, contractility, duration of contraction, EDV (preload), resistance (afterload)

Question 16

What is EDV? And what is it used for?

Answer 16

Amount of blood in the ventricles before the heart contracts. The greater the EDV, the greater the SV.
Used to estimate the hearts preload volume and to calculate SV and EF.

Question 17

Outline the parasympathetic regulation of HR

Answer 17

Parasympathetic stimulation from cardio inhibitory centre in medulla oblongata.
Parasympathetic input via Vagus nerve which synapses with postganglionic cells in SAN and AVN, stimulating release of Ach. This decreases HR.

Question 18

Outline the sympathetic regulation of HR

Answer 18

Sympathetic regulation from cardioacceleratory centre in medulla oblongata.
Sympathetic input via sympathetic cardiac nerves to sympathetic trunk and into heart by postganglionic fibres. Synapses at SAN, AVN, atria and ventricles. Stimulates release of adrenaline, increasing HR and force of contraction.

Question 19

Outline the baroreceptor reflex that increases bp

Answer 19

Baroreceptors in carotid sinus and aortic arch detect increase in arterial pressure and communicate this to medulla oblongata. There, there is decreased stimulation to the cardiac inhibitory, increased stim to the cardiac acceleratory centre and vasomotor centre. This results in increased HR and increased vasoconstriction, which increases bp.

Question 20

What drug is often given to slow HR?

Answer 20

Beta blockers

Question 21

Outline the acute CV response to exercise

Answer 21

-Redistribution of blood flow - increased bf to muscles, heart 
Decreased bf to skin and gastro, 
-increased HR,
-a-vo2 diff increases 
-CO increases
-SV increases
-BP increases

Question 22

Those experienced heart failure had lower cardiac power output and a greater a-vo2 diff than healthy patients.

Answer 22

Fact

Question 23

Outline the chronic CV response to exercise

Answer 23

Heart: (stronger heart muscle and better collateral circulation)
- increased contraction-relaxation velocity, myocyte size, LV wall compliance, ion channel expression, CO and decreased resting HR.
Blood vessels:
-decreased aortic valve calcification, atherosclerotic plaque formation, vascular resistance, resting BP and increased organ perfusion and eNOS expression.
Blood:
-changes to plasma lipid profile, increased insulin sensitivity, erythropoietin and O2 carrying capacity, improved glycemic control.

Question 24

Metabolic and CV function decline with age.

Age = major risk factor for CV morbidity + mortality

Answer 24

Fact

Question 25

How could we evaluate cardiac function in the ageing heart?

Answer 25

Thermodilution, direct fick, re-breathing techniques, bioreactance and bioimpedance

Question 26

A higher level of daily PA preserves cardiac metabolism and exercise capacity with ageing.
It has limited effects on age related changes in concentric remodelling, diastolic function and cardiac performance.

Answer 26

Fact