Cardiac Specialization, Aging, Heart Failure Flashcards
What is the #1 worldwide cause of mortality?
Cardiovascular Dz (CAD, stroke, peripheral vascular dz)
1/3 of deaths in USA
How does heart weight vary from person to person?
Varies with body habitus
Approx 0.4-0.5% body weight
Describe the thickness of right an left ventricles.
Rt = 0.5 cm thickness Lt = 1.5 cm thickness
What is hypertrophy of the heart?
Increased ventricular thickness
What is dilation of the heart?
Enlarged chamber size
What is cardiomegaly of the heart?
Increase in cardiac weight
Describe the myocardium. What hormone does it release? What does this hormone do?
Atrial myocytes have storage granules that contain atrial natriuretic peptide (ANP)
Promotes arterial vasodilation and stimulates renal salt and water elimination (natriuresis and diuresis) –> beneficial in setting of HTN and CHF
How are myocytes arranged in the ventricles and atrium?
Lt ventricle = arranged circumferentially in spiral orientation that helps generate coordinated wave of contraction the spreads from apex to base of heart
Rt ventricle = Less structured, contractile apparatus organized in series of subunits called sarcomeres
Atrial myocytes = haphazardly arranged, generate weaker contractile forces
Describe the structure of valves.
Lined by endothelium and share similar tri-layered architecture:
- fibrosa = dense collagesous core at outflow surface
- spongiosa = central core of loose CT
- ventricularis/atrialis = rich laryer of elastin on inflow surface
How do valves receive their nutrient?
Due to thin structure, derive most of nourishment via Diffusion
What are 3 types of damage that can happen to valves?
Damage to collagen = weakens (ex: mitral prolapse)
Nodular calcification (ex: calcific aortic stenosis)
Fibrotic thickening (ex: rheumatic heart dz)
Describe the conduction of the heart.
Responsible = SA node (Pacemaker) AV node Bundle of His Purkinje network
Normal rate spontaneous depolarization of SA node (60-100 bpm) is faster, thus sets pace typically
What are the main arteries supplying blood to the heart?
3 major epicardial coronary arteries, form corona (crown) at base of heart:
- LAD (left anterior descending) - diagonal branches
- LCX (left circumflex) - marginal branches
- RCA (right coronary)
What happens during ventricular diastole?
Aortic valves closes leading to blood flow to the myocardium
What are cardiac stem cells? How much of the heart do they replace? Can they undo necrosis?
Bone marrow derived precursors and stem cells present in myocardium
Only replaces ~1% each yr
No significant recovery in zones of necrosis
What changes can occur in the myocardium and chambers with aging?
Increase in LV cavity/volume is reduced
Increase in epicardial fat
Myocardium changes =
- Lipofuscin granules (the more you have, more stress heart is under)
- Basophilic degeneration
What changes can occur to the valves with aging?
Aortic and mitral valves annular calcification
Fibrous thickening
Mitral leaflets buckle towards Lt atrium –> increase in left atrium size
Lambl excrescences = small filiform processes form on the closure lines of aortic and mitral valves, probably resulting from organization of small thrombi
What changes could occur to the cardiac vasculature with aging?
Coronary atherosclerosis
Stiffening of the aorta
What is pump failure?
Myocardium contracts weakly during systole and there is inadequate cardiac output.
It may also relax insufficiently during diastole to permit adequate ventricular filling
What is flow obstruction?
When lesions:
- obstruct blood flow through a vessel
- prevent valve opening
- cause increased ventricular chamber pressure
Valvular blockage causes increased pressure overloading the chamber that pumps against obstruction
What is regurgitant flow?
Portion of the output from each contraction flows backward through incompetent valve, adding volume overload to affected atria or ventricles
What is shunted flow?
Blood can be diverted from one part of heart to another through defects that can be congenital or acquired.
Can also occur between blood vessels (ex: Patent Ductus Arteriosus)
What are disorders of cardiac conduction?
Conduction defects or arrhythmias due to uncoordinated generation or transmission of impulses lead to nonuniform and inefficient myocardial contractions
What happens with rupture of the heart or major vessel?
There is a cataclysmic exsanguination either into body cavities or externally
