CHARACTERISTICS OF THE CARDIOVASCULAR SYSTEM,
ABNORMALITIES AND DISEASES PART 1
Miklós Székely and Márta Balaskó
Molecular and Clinical Basics of Gerontology – Lecture 8
In 1995 the leading causes of death were:
1 Cardiovascular 50.7%
2 Malignancies 22.9%
3 Diseases of the GI tract 8.1%
4 Injuries, poisons, violence 7.8%
Leading cause of death in both gender was
cardiovascular (even preceding malignancies)
• 65-74 years 50-52%
• above 75 years 60%
• Each ventricle pumps 200,000 m blood in 60 years through 40,000 km long capillary system with 1,000 m2 surface
• The aging of the cardiovascular system determines survival and longevity (100-120 years).
Autonomic modulation Autonomic
modulation
Growth factors (AII, NE, ET,
TGFβ)
Cardiac factors:
Contractility Stretch (systolic, diastolic)
Vascular factors:
Pulsatile elastance reflected waves
Nonpulsatile PVR
• In normotensive individuals a moderate, age-related thickening of the ventricular wall may be physiological
• The size of the left atrium and the internal diameter of ventricle also increases with age (not always statistically significant)
• On a chest X-ray an increase of heart contours is observed
• Hypertrophy of the myocytes is mostly behind the thickening of the ventricular wall, but increase in the connective tissue (fibrosis) also contributes
• Fibrosis and calcification may be observed everywhere within the heart (aortic valve, annulus fibrosus),
ventricular compliance decreases
• Early diastolic filling of the heart decreases (at the age of 80 years ca. 50%, in the young 2× as much blood flows into the ventricle than in later phases)
• The mitral valve closes more slowly
• The late diastolic filling is quicker/more effective (due to the contraction of the heart) (filling in the elderly early:late=1:1)
• EDV mostly increases particularly in males
During Exercise At rest
Young heart
Old heart
Size at the end of heart beat is smaller than at rest Size at the start of heart beat
is the same as at rest
Size at the start of heart beat is larger than at rest
Size at the end of heart beat is the same as at rest At the end of
heart beat, at rest At the start of
heart beat, at rest
At the start of heart beat, at rest
At the end of heart beat, at rest
• The number of the atrial pace-maker cells decreases 50-75% by the age of 50 – pulse decreases
• The cell count of the AV node is maintained, but the speed of conduction is slower
• His cell count decreases – fibrosis
• The heart rate at rest remains normal, but exercise induced maximum decreases by 30% (by the age of 80) the maximal possible heart rate and cardiac
output decreases to the same extent
• The responsiveness to b-adrenergic effects
decreases (changes in the membrane G-proteins)
D
A B C
20
16
12
8
4
20 40 60 80
Age (years)
Cardiac output (L/min)
• The arterial wall becomes more rigid, the aorta shows distension: due to the quantitative and
qualitative changes in elastin and collagen fibers.
• Calcium deposition and collagen cross-links make the vessels even more rigid.
• Glycoprotein disappears from the elastic fibers, they become fragile/brittle, the mineral content of the
elastin increases, the polar amino acid content also rises.
• The elasticity of the aorta is diminished, during diastole the pressure falls steeply!
(It decreases coronary circulation!)
• Remodelling of the small vessels, the functional capillary number decreases – the oxygen supply of the tissues
decreases!
• The thickness of the tunica intima and media increases, e.g.
in the a. carotis communis the normal mean of 0.35 mm – may increase to 2-3-times higher (higher levels of growth factors, smooth muscle proliferation, transformation)
• The tone of the vessels changes
NO decreases, ROS, TxA2 PGH2 increase Ca-dependent vasoconstriction is
Ca-activated or voltage-dependent K+-channel a-subunit
density decreases in the vascular smooth muscle membranes
• Besides all these, atherosclerosis further increases the rigidity of the vessels (depending on severity)
• The myocardial contractility decreases
• The duration of both the systole, and the diastole increases (slower) (ionflux of the L type Ca++
channels increases, their activity becomes longer)
• Due to the fall of the diastolic pressure the coronary circulation decreases
Ventricular filling, preload
• The early filling becomes progressively slower after the age of 20, by 80-y it is only half of the original
• despite this, the EDV does not decrease in healthy old people, because the major part of the filling
takes place in the second phase
• The enlargement of the atria and their stronger
contraction is responsible for the late filling (at 20-y 20%, 80-y 40%)
90
80
70
60
50 0 20 40 60 80 100 Age (years)
Early diastolic filling volume (% of total filling volume)
50
40
30
20
10 0 20 40 60 80 100 Age (years)
Late diastolic filling due to atrial contraction (% of total filling volume)
men women
Ventricular filling , preload
• In auscultation 4th (atrial) sound appears – gallop rhythm
• In acute atrial fibrillation the loss of
coordinated atrial contraction leads to a loss of this function. In people with chronic left
ventricular failure it leads to an acute heart
failure
Afterload
• the vessels are more rigid
• the speed of the pulse wave is up – with a quick reflection of the pulse wave, already within the systole, interference of waves may decrease the coronary circulation
• the sensitivity of the baroreceptor reflex decreases
• the systolic blood pressure increases
• the ventricular emptying is impaired
• dilatation of the left ventricle
• the thickening of the ventricular wall may have benefits according to the LaPlace law), normalizing the systolic function and the ejection fraction
In case of an abnormal blood pressure, treatment is necessary – isolated systolic hypertension
The myocardial performance, i.e. the cardiac
output depends (besides the pre- and afterload)
on the contractility of the heart
arterial stiffening
pulse wave velocity
and early reflected
waves
systolic blood pressure
with late peak
LV wall tension
LV hyper- trophy
Normali- sation of
LV wall tension
normal end-systolic volume and
ejection fraction
aortic root size
prolonged contraction
early diastolic
filling
atrial size
atrial filling and contraction
Normal end-diastolic
volume
