CV week 4 Flashcards
Secondary Prevention of CAD
actions taken after the development of disease to halt its progress and subsequent complications
-For pts with confirmed CAD or vascular equivalent (AAA, claudication, stroke)
Goal: prevent plaque rupture and progression
Pharmacologic reduction of CV risk with _____, ______ and ______
Anti-platelet
B-Blockers
RAAS Inhibitors
Anti-platelet guidelines for CV risk reduction:
ASA alone? (2)
ASA + Clopidogrel? (1)
ASA or Clopidogrel alone? (2)
ASA alone:
- ALL CAD pts
- low dose for all pts on warfarin
Clopidogrel + ASA:
-all pts with ACS, PCI, or CABG for one year following event
ASA or Clopidogrel alone:
- all symptomatic (not asymptomatic) peripheral artery disease pts
- post-stroke pts (can do both ASA/Clopidogrel together also)
Class I and Class IIa
Beta-blocker guidelines for reducing CAD risk
Class I: B-blocker in all LVSD (EF less than 40%) and HF symptoms or MI/ACS in prior 3 years
Class IIa:
- B-Blockers in all with LVSD (EF less than 40%) even in absence of HF symptoms
- B-blocker in all with any history of MI/ACS
Goal of anti-platelet therapy in CAD secondary prevention:
prevent platelet adhesion to site of ruptured plaque, reduce platelet activation with use of _______, and prevent platelet aggregation with use of _______
ASA
Clopidogrel
Goal of B-blocker therapy in CAD secondary prevention
reduce HR, reduce contractility, reduce conduction velocity, reduce systemic BP → reduce myocardial oxygen demand
Goal of RAAS inhibition in CAD secondary prevention (4)
vasodilation, natriuresis, decreased SNS activity, reduce cardiac remodeling
Class I RAAS inhibition guidelines:
ACEI
ARBs
Aldosterone inhibtion
ACEIs:
-all with LVSD (EF less than 40%), DM, HTN, or chronic kidney disease
ARBs:
-all with LVSD (EF less than 40%) and prior MI or HF symptoms who are ACE INTOLERANT
Aldosterone Inhibition:
- Post MI pts with LVSD (EF less than 40%) who are also taking BB, ACEI/ARB and have HF or DM
- AVOID in renal dysfunction or significant hyperkalemia
BP target goals
> 60yrs –> 150/90
less than 60yrs –> 140/90
Typical strategies for controlling BP
1) Lifestyle (reduce saturated fat/sodium - DASH diet)
2) RAAS inhibitors (ACEis, ARBs)
3) Diuretics
4) Ca2+ channel blockers
5) B-blockers (not the best for HTN)
6) Direct vasodilators (only in certain pts)
Lipid management for CAD secondary prevention
STATINS IN ALL CAD PATIENTS
-High dose statins more efficacious in reducing cardiac events
(Biggest side effect is myalgias)
-Non-statin lipid treatments have been shown to reduce lipid levels, but did NOT reduce cardiac events
Pharmacologic/Lifestyle strategies to reduce CAD risk (5)
1) BP control
2) Lipid management
3) Diabetes management
4) Depression screening and treatment
5) Smoking cessation
Lifestyle strategies for reducing CAD risk
1) Weight management
2) Physical Activity
Role of Monocytes in atherogenesis and disease progression (5)
innate immune system leukocyte
1) Monocytes adhere to endothelial cells expressing VCAM-1 and other adhesion molecules
2) Respond to chemokines (MCP-1) and migrate into intima
3) → Macrophage activation and ingestion of oxLDL → Foam cell
4) Secretion of IL-1, TNF, IFN-y and other proinflammatory mediators
5) Macrophage apoptosis promotes atherosclerosis progression
Role of T cells in atherogenesis and disease progression
Dendritic cell antigen presentation (connection between innate and adaptive immunity)→ T cell activation → clonal T cell expansion (Th1, Th17, Treg)
Th1 and atherogenesis
IFN-y secretion
- Mediates progression of atherosclerosis in conjunction with macrophage apoptosis
- Increases lesion formation and plaque vulnerability
Th17 and atherogenesis
promote plaque instability and angiogenesis (IL-17, IL-22, IL-21 secretion)
Treg and atherogenesis
→ IL-10, TGF-B
Decreased lesion formation and plaque vulnerability
Inflammatory cells and atherogenesis summary
- Immune response to injury initiates atherogenesis
- Innate immune cell interaction with endothelium drives initial plaque formation
- T cells promote further lesion expansion and plaque vulnerability
Drivers of Plaque Instability: (3)
Macrophage apoptosis and necrosis promotes necrotic core
MMPs degrade fibrous cap (Type I collagen)
Intra-plaque hemorrhage further weakens core
CRP
predicts excess risk of CV events (not yet used clinically)
- Acute phase reactant produced by hepatocytes, macrophages, and smooth muscle cells
- Binds to: modified membranes, apoptotic cells, lipoproteins
- Activates classical complement pathway
Link between autoimmune disease and CV events
Treatment of autoimmune disease (psoriasis, RA) associated with a lower risk of CV events
Shows that targeting inflammation can help reduce CV evnts
-TNF-alpha, IL-6, IL-1 inhibition = possible treatment
Risk factors for peripheral artery disease (4)
Diabetes (4x risk)
Smoking (2-3x risk)
Lipids (2x risk)
HTN (2x risk)
Peripheral artery disease results in 6x increased risk of ______
CV death
Intermittent claudication
- cramp, calf fatigue with exercise, resolves with rest
- Blood flow normal at rest, limited with exercise
Ischemic LE rest pain
Pain in distal foot or heel, worsened by leg elevation and improved by dependency (hanging feet down off bed)
- Distal, painful ulcers on toes or heels
- Blood flow limited at rest and exercise
Physical exam signs of ischemic leg rest pain
Decreased or absent pulses
Bruits (abdominal, femoral)
Muscle atrophy
Severe PAD → pallor of feet with elevation, dependent rubor, ischemic ulcers, ischemic gangrene
Risk Factors for Abdominal Aortic Aneurysm (4)
Age, gender (male), smoking, family history
Normal aorta size vs. AAA size
Normal aorta: 3cm at root, 2.5-2cm for remaining
AAA: diameter > 3.0 cm (50% increase in size relative to proximal normal segment)
**5.0-5.9 cm diameter → 35% 5 year rupture rate
Arterial Aneurysm
pathological expansion of all three arterial layers
Arterial aneurysm mechanism of formation (4)
1) Weakened aortic wall (decreased elastin and collagen)
2) Inflammation (B and T lymphocytes, macrophages, cytokines, autoantigens)
3) Proteolytic Enzymes (increased MMP)
4) Biomechanical stresses (elastin distribution, turbulent blood flow, mural thrombus)
Clinical presentation of arterial aneurysms
- 70% pts asymptomatic → sudden death
- 30% have abdominal pain radiating to back → die
- Often incidental discovery from imaging for another problem
**Arteriography may miss aneurysm because it view LUMEN NOT ARTERIAL WALL
Risk factors for aortic dissection (9)
1) HTN
2) Drugs (cocaine)
3) Inherited connective tissue disorders (Marfan, Ehlers-Danlos Syndromes)
4) Bicuspid aortic valve
5) Coarctation
6) Pregnancy
7) Aortitis
8) Iatrogenic (surgery, arterial catheterization)
9) Trauma
Aortic dissection 2 possible mechanisms of formation?
vessel loses integrity due to disruption in vessel wall
1) Primary intimal tear
2) Rupture of vasa vasorum
Clinical manifestations of aortic dissection
Severe tearing pain
-Disruption of major arterial circulation (due to formation of false lumen blocking flow to particular area)
→ stroke (carotid), syncope (vertebral), MI (coronaries), intestinal ischemia (mesenteric vessels), renal failure (renal arteries)
Virchow’s Triad
Injury
Abnormal flow (stasis)
Coagulation Factors
Fick equation
CO= VO2/a-v O2
What does the Fick equation tell us?
Relates respiratory VO2 (max oxygen consumption) with oxygen delivery (circulatory system), and oxygen extraction (skeletal muscle)
Fick equation during exercise
- 5 fold increase in CO
- 3 fold increase in a-v O2
- Oxygen consumption during exercise influence more by CO and blood flow than by oxygen extraction
What happens during exercise (3)
1) Increase in blood flow
- Increase Cardiac Output by :
a. Increase HR (Cannot increase HR alone, fast HR → shorter diastole)
b.Increase EF
At rest, normal LVEF is 60% → EF increases by 10-20% with exercise
2.Muscle Blood flow
- Redistribution of blood flow:
Inactive organs → active skeletal muscle
3) Maintain Blood Pressure
a. Driving force of blood flow
b. Maintain blood flow to vital organs (brain)
Heart rate response to exercise
HR increased with exercise → increase SV (peripheral vasodilation, increased venous return, venoconstriction)
i. HR increase directly related to exercise intensity
ii. Linear response of HR to workload up to near max exercise
iii. Max exercise HR highly reproducible and consistent (220-age)
- After age 15, max HR decreases by 1 bpm annually
iv. During lower levels of exercise, increase in HR up to 100bmp related to parasympathetic withdrawal
- Above that (moderate/heavy exercise), HR controlled by sympathetic activity
Stroke volume during exercise
SV increases during exercise up to workloads 40-60% max exercise, and then SV reaches a plateau with no further increases
Factors responsible for changes in stroke volume during exercise
- Increased venous return:
- Venoconstriction (SNS activity on VSM)
- Muscle pump (venous return)
- Respiratory pump (negative thoracic pressure aids venous return)
2) Increased Ventricular Contractility:
- Increased SNS activity (direct innervation and elevation of NE/E)
- Frank Starling Effect - increased stretch of ventricular muscle fibers → enhanced contractility
Differences in athletes (like Josh)
Starling curve shifted left - greater increase in SV for any EDV value
- Greater resting SV and some athletes even get continued SV increase throughout exercise → greater CO
- Increased EDV with enhanced Starling forces at lower levels of exercise and increased ventricular contractility at higher levels of exercise
2.Greater resting SV with lower resting HR → same CO during rest as untrained people ( 4.5-5 L/min)
- Max CO is greater in trained athletes than untrained
- Max CO = 24-34 L/min (6-7 fold increase)
4.Chronic LV dysfunction: Starling curve shifted right, and flatter → less preload effect on SV
Untrained people (Charlie) during exercise
- SV doubles with exercise, but starts at a lower level than athletes
- Max CO = 18-22L/min (4-5 fold increase)
Cardiac output during exercise
i. Increase in CO proportional to metabolic rate and VO2 required to perform the exercise
ii. CARDINAL RULE: it requires 6 L/min in CO for each 1L/min increase in oxygen uptake beyond resting conditions
- Workload 50% VO2 max → increases in HR only → increase CO
EXCEPTION IS ELITE ATHLETES (increase SV throughout exercise)
iii.Max CO depends on body size (gender differences) and the degree of exercise conditioning
BP during exercise
Decrease in vascular resistance + increase in CO → BP maintained
- Increase in blood flow achieved by decrease in vascular resistance and NOT increase in BP
- Get some increase in systolic BP, little change in diastolic BP
MAP
= ⅓ systolic + ⅔ diastolic
1.MAP determines rate of blood flow through systemic circuit
- Systolic pressure: pressure generated as blood is ejected from LV
a. The same as LV systolic pressure in absence of aortic valve obstruction - Diastolic pressure: pressure during ventricular relaxation
a. Reflects compliance of systemic vascular bed
Blood flow determined by: (3)
- Autoregulation in exercising beds
- Capillary recruitment
- vasoconstriction of non exercising beds
Autoregulation
- Local release of substances at time of exercise→ Vasodilation in response to decreased PO2, increased PCO2, NO, [K+], acidosis, and adenosine
- Intrinsic metabolic control
- Regulation at arterioles and small artery level
Capillary recruitment
- At rest only 5-10% capillaries in skeletal muscle open
2. During exercise → 100% of capillaries open → increase surface area for oxygen delivery and extraction
Vasoconstriction of non exercising muscle bed
- Number of motor units recruited determine need for muscle blood flow and redirection of CO from non exercising vascular beds
- SNS regulation increases vasoconstriction
- Regulation by muscle ergoreceptors and CV control center (medulla)
Blood flow redistribution during exercise->
Increased muscle blood flow
i. At rest skeletal muscle blood flow = 15-20% total CO, increases to 80-85% during exercise
ii. Vasodilation to exercising muscle bed, vasoconstriction of non-exercising vascular beds (liver, kidneys, intestines)
iii. Blood flow to brain maintained during exercise
SNS activity and blood flow
key for maintaining blood flow to vital organs
i. Moderate to Heavy Exercise:
1. Sympatholysis → vasodilation and NOT constriction
2. MAP maintained by CO and vasoconstriction in non exercising vascular beds
ii. Very High Workloads:
1. Muscle vasodilation exceeds cardiac pump capacity
2. Sympathetic mediated vasoconstriction in exercising vascular beds to preserve MAP and blood flow to brain, etc.
Coronary vs. systemic circulation
Coronary: increases during exercise in proportion to increase in CO
- At rest coronary venous O2 sat = 25% (mixed systemic venous O2 = 65%)
a. HIGH LEVEL OF OXYGEN EXTRACTION AT REST - During Exercise coronary O2 sat = 10% (slight increase in extraction)
- Coronary blood flow primary way to improve oxygenation of myocardium
Oxygen delivery =
blood flow x arterial O2 content
i. Blood flow = CO
ii. Arterial O2 content = [Hgb] x 1.34 x O2 saturation (%)
Arterial-venous O2 content difference
At Rest: arterial O2 content = 20 ml per 100 ml blood and venous O2 content = 15 ml per 100 ml blood
-> a-v O2 difference at rest = 5 ml O2 per 100 ml blood
At high intensity exercise: arterial = 20 ml, venous = 5 ml
-> a-v O2 difference at exercise = 15 ml O2 per 100 ml blood
**No change in arterial oxygen content, only change O2 extraction
Rate pressure product
RPP = HRmax x SBPmax
- RPP (heart rate) where ischemia occur - determines the severity of coronary disease
- Fixed stenosis → fixed RPP
- Dynamic stenosis → variable RPP
Blastocyst is made up of what 2 layers?
Trophoblast = outer cell mass Embryoblast = inner cell mass
The Trophoblast gives rise to…
The Embryoblast gives rise to…
Trophoblast –> placenta and supporting tissues
Embryoblast –> the baby! aka Embryonic Disc
The Embryonic disc (Embryoblast) is made up of what to layers?
Epiblast (external layer)
Hypoblast (internal layer)
Epiblast cells migrate through the primitive streak to give rise to the 3rd layer of the embryonic disc called ______
mesoderm
Gastrula: 3 germ layers
1) Ectoderm (external)
2) Mesoderm (middle)
3) Endoderm (internal)
Precardiac cells orgininate from which germ layer?
Mesoderm - migrate cephalically
By day 19, the precardiac cells within the _______ area migrate _______ and begin to form _________
cardiogenic area
cephalically, so they are ventral to forebrain and foregut
begin to form 2 endocardial tubes
The two primitive endocardial tubes are formed of ______ and ______ and come together to form _________
endothelial cells
surrounded by splanchnic mesoderm
primitive heart tube