(pic on slide 157) (1) Eccentric- (The wall thickness normally increases in proportion to the increase in chamber radius) (2) concentric- (the chamber radius may not change; however, the wall thickness greatly increases)
why does eccentric hypertrophy occur? examples?
occurs because of increased blood volume such as in hypervolemia, valvular insufficiency, septal defects, polycythemia
explain how eccentric hypertrophy occurs (cellularly), and how it looks as a result
chamber dilation occurs as new sarcomeres are added in-series to existing sarcomeres
what does concentric hypertrophy occur? examples?
occurs because of increased blood pressure such as in valvular stenosis, vascular disease, pulmonary disease, hyperthyroidism in cats, hypertension in cats and dogs
which type of hypertrophy does hyperthyroidism in cats cause?
concentric (wall thickening) one
explain how concentric hypertrophy occurs (cellularly), and how it looks as a result
wall thickness greatly increases as new sarcomeres are added in-parallel to existing sarcomeres
what are some underlying features of cardiac hypertrophy?
increase in cardiomyocyte size, enhanced protein synthesis, higher organization of the sarcomere
uhhhhh what's a sarcomere again?
the basic unit of a muscle. (the thing with the bands, like I band, A band..) basically the muscle fiber is made of myofibrils bundled together, and each myofibril is composed of strings of sarcomeres (which have the various bands in them) (see slide 156 for a pic)
what's the pathogenesis of cardiac hypertrophy in a healthy myocardium?
stretching of fibers from increased work load →fiber hypertrophy if healthy myocardium
what are the three stages of hypertrophy?
initiation, stable hyperfunction, deterioration of function
what limitations does hypertrophy impose on the heart? (4)
(1) blood supply (2) mechanical effect of increased muscle mass on function of adjacent areas of the heart (3) loss of compliance of myocardium (4) lack of adequate energy production (because of an increased myofibril to mitochondria ratio)
what is the gross appearance of eccentric hypertrophy?
large chamber with thinned or normal thickness walls, rounded shape to heart, double apex
what is the gross appearance of concentric hypertrophy?
small chamber with thick walls
how does hypertrophy look histologically?
fibers are thick and have large nuclei
what is a specific disease example of hypertrophy in cattle?
"brisket disease ", "high altitude disease" (result of pulmonary arterial hypertension induced by pulmonary hypoxia occurring at high altitude.)
what is a specific disease example of hypertrophy in dogs?
dirofilariasis (infection by parasites in the Dirofilaria genus-- ie heartworms)
what is a specific disease example of hypertrophy in cats?
explain how "brisket disease "/"high altitude disease" in cattle causes hypertrophy (and other problems)
hypoxic conditions over 7000 feet result in pulmonary hypertension--> right heart failure with subcutaneous edema of the brisket--> RV hypertrophy--> chronic passive congestion of the liver ("nutmeg liver“).
explain how dirofilariasis in dogs causes hypertrophy
the parasites cause pulmonary vascular lesions (arteritis)--> produces pulmonary hypertension --> RV hypertrophy--> R heart failure
explain how hyperthyroidism in cats causes hypertrophy
can happen in functional thyroidal adenomatous hyperplasia or functional adenomas. The hormones cause prominent myocardial hypertrophy (LV)
when the vessels respond to injury, there is a complex interaction among what two things?
Complex interaction among the cellular and non-cellular elements of the vessel wall and the cellular and non-cellular elements of the blood
what are the two major post-mortem changes you will see in the vessels?
(1) Imbibition of blood- red staining of the intima by Hb (2) clotting-- can have "currant jelly" or "chicken fat" types (May be absent if death from hypoxia)
when might clotting be abset in vessels post-mortem?
May be absent if death from hypoxia
what is a congenital anomaly of the vessels?
Lymphatic hypoplasia--> what does this congenital problem cause? who is it hereditary in? what is it called in dogs?
Produces anasarca (generalized edema), it is hereditary in Ayrshire cattle, and in dogs it is called hereditary lymphedema
Where do HORSES usually get a rupture of a vessel? Why does this happen/what happens once there is a rupture?
usually rupture of the AORTA! (also carotid but that's a diff card) usually intrapericardial hemorrhage associated with exertion
where do TURKEYS (esp MALES) usually get a rupture of a vessel? which type of rupture is it, and what is the result of this?
usually rupture of the aorta! They are often the dissecting type--> rupture--> exsanguination
who usually gets a rupture of the CAROTID artery, and why? what is a common clinical sign?
HORSES, it is usually secondary to gutteral pouch mycosis--> epitaxis
who is prone to get a rupture of the thoracic duct? (lymph vessel). what condition does this cause?
CAT AND DOG, results in chylothorax....cause usually not determined
what causes hypertrophy of the vessels?
increased volume and pressure load
what are some examples of increased volume and pressure load of vessels caused hypertrophy? (8)
(1) uterine arteries in pregnancy (2) pulmonary vessels in cardiac shunts (3) "high altitude disease" (4) Aelurostrongylus sp (Cat nematode) (5) Toxocara sp. (round worms) (6) dirofilariasisin cats (7) ergot and fescue toxicosis (8) idiopathic in cats
how do the lesions of hypertrophy of vessels appear?
thick walls, medial hyperplasia
Big cause in cattle and big cause in dogs of vessel hyperplasia? (in red)
cattle=Brisket dz. Dog= dirofilariasis
what is an Aneurysm, what is it a type of?
type of dilation- it is a thin outpouching of arterial wall, subject to rupture
what are three things that can cause an aneurysm?
(1) Cu deficiency (2) lathyrism (sweet pea toxicosis) (3) in HORSES, strongylosis (equine intestinal threatworm)
(what are Varicosities?)
(vericose veins) elongation and dilation of veins
what is Arteriosclerosis?
“hardening of arteries”
what is Atherosclerosis?
Atherosclerosis is a specific type of arteriosclerosis, Atherosclerosis refers to the buildup of fats, cholesterol and other substances in and on your artery walls (plaques), which can restrict blood flow
what are two causes of Atherosclerosis?
(1) hypercholesterolemia (2) hypothyroidism
explain the pathogenesis of ATHEROsclerosis
high dietary cholesterol and saturated fat intake--> high level of serum LDL--> increased permeability of endothelium--> entry of lipids into wall to form lesions
4 charateristic lesions of ATHEROsclerosis?
(1) fatty streaks on intima early (2) later, thick rough plaques on intima and adhered thrombi (3) accumulation of "foam cells" in intima and media (4) fibrosis
what are foam cells? when do you see them?
Foam cells are fat-laden macrophages seen in atherosclerosis. They are an indication of plaque build-up, or atherosclerosis