lecture 5a Flashcards

1
Q

ischemia heart disease (IHD) definition

A

a condition in which there is an inadequate supply of blood & oxygen to a portion of the myocardium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

IHD typically occurs when

A

there is an imbalance between myocardial oxygen supply ad demand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

the most common cause of myocardial ischemia is

A

atherosclerotic disease of an epicardical coronary artery (90%) sufficient to cause a regional reduction in myocardial blood flow and inadequate perfusion of the myocardium supplied by the involved coronary artery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the most common serious, chronic, life-threatening illness in the US?

A

IHD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are associated with IHD

A

genetic factors, high-fat & energy rich diet, smoking & a sedentary lifestyle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

powerful risk factors for IHD

A

obesity, insulin resistance, & T2DM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

MVO2 (myocardial oxygen demand)=

A

O2 delivery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

hypoxia

A
  • lack of oxygen
  • exacerbates effects of atherosclerosis
  • anemia
  • cyanotic heart disease
  • advanced lung disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

ischemia

A

mainly lack of oxygen, but also nutrients

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

factors that effect MVO2 (myocardial oxygen demand)

A
HR
myocardial contractility
myocardial wall tension (stress)
BP
ionotropic status
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

adequate oxygen-carrying capacity of blood is determined by

A
  • inspired level of oxygen
  • pulmonary function
  • hemoglobin concentration & function
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

blood flows through the coronary arteries in a phasic fashion, with majority occuring during

A

diastole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

75% of the total coronary resistance to flow occurs across 3 sets of arteries

A
  1. Large epicardial arteries (R1)
  2. prearteriolar vessels (R2)
  3. arteriolar & intramyocardial capillary vessels (R3)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

in the absense of significant flow-limiting atherosclerotic obstructions, R1 is tirvial:

A

the major determinant of coronary resistance is found in R2 and R3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

coronary circulation is controlled by the heart’s requirements for oxygen

A

metabolic regulation

auto regulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

metabolic regulation

A

exercise, emotional stress (coronary vascular resistance)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

auto regulation

A

the coronary blood flow is maintained on the same level, independently on physiological alterations in BP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

large portion of the myocardium is effects if atheroscleosis occurs

A

in left coronary artery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

rupture

A

fibrous cap is broke

- tissue factor is released & initiates coagulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

other causes of ischemia

A
  • spasms: prinzmetal’s angina
  • thrombi
  • emboli
  • BP decrease
  • ostial narrowing due to aortitis
  • congenital abnormalities
  • severe left ventricular hypetrophy due to aortic stenosis
  • severe anemia or the presence of carboxyhemoglobin
  • abnormal constriction or failure of normal dilation of the coronary resistance vessels
21
Q

where does atheroscleosis occur?

A
  • sites of increased turbulence in coronary flow

- brand points in the epicardial arteries

22
Q

risk factors for atherosclerosis & IHD

A
high LDL
low HDL
smoking
HTN
DM
23
Q

severity of symptoms depends on

A

degree & location of stenosis & how fast it develops

24
Q

50% stenosis

A

limited ability to increase blood flow in the response to an increased demand

25
80% stenosis
blood flow at rest may be reduced
26
stenosis where are particularly hazardous?
of the left main coronary artery of the proximal left anterior descending coronary artery
27
gradually developing stenosis causes formation of
collateral vessels | - these are good!
28
stenosis of the epicardial artery leads to
the dilation of the distal resistance vessels
29
effects of ischemia
- inadequate perfusion - decreased myocardial O2 tension - mechanical, biochemial & electrical disturbances - regional disturbances of ventricular contractility - segmental hypokinesia - segmental akinesia - segmental dyskinesia - reduced myocardial pump function
30
effects of acute ischemia
(failure of relaxation & contraction) - transient left ventricular failure - mitral regurgitation if the papillary muscle apparatus is involved
31
left ventricular failure
- worst scenario! - dramatic < BP - hypoperfusion to the brain - stroke
32
mitral reguritation
- blood flowing back | - problems in the pulmonary circulation
33
transient ischemia
angina pectoris
34
prolonged ischemia
actute MI
35
infarction=
tissue necrosis | - irreversible tissue damage
36
ECG effects of ischemia
- nature of process (reversible vs irreversible - duration (acute vs chronic) - the extent (transmural vs subendocardial) localization (anterior vs inferioposterior) - presence of other underlying abnormalities (ventricular hypertrophy, conduction defects)
37
ST depression
Partial thickness | possible ischemia
38
ST elevation
total thickness | MI
39
effects of ischemia: arrhythmias
- electrical instability, which may lead to isolated ventricular premature beats or even ventricular tachycardia or ventricular fibrillation - most patients who die suddenly from IHD do so as a result of ischemia-induced ventricular tachyarrhythmias
40
IHD can be classified as
chronic coronary artery disease or | acute coronary syndromes
41
chronic coronary artery disease (CAD)
stable angina
42
acute coronary syndromes (ACS)
- STEMI - unstable angina - NSTEMI - sudden cardiac death - prinzmental's variant angina
43
CAD- stable angina pectoris clinical manifestations
- male >50 or women >60 - chest discomfort - crescendo-decresendo - can radiate down shoulder & to both arms - can arise or radiate to the back, interscapular region, root of neck, teeth & epigrastric - rarely localized below umilicus or above mandible - episodes typically caused by exertion or emotion, heavy meal or cold - symptoms releived by SL NTG***
44
symptom of myocardial ischemia
- angina - dyspnea - nausea - fatigue - faintness
45
may indicate UA
- angina occurring with less exertion than in the past, occurring at rest or awakening the patient from sleep
46
patients should be questioned & examined for
claudication, stroke & transient ischemia attacks
47
evidence of atherosclerotic disease at other sites
- abdominal aortic aneurysm - carotid arterial bruits - diminished arterial pulses on lower extremities
48
laboratory exam
- check urine for evidence of DM & renal disease - cholesterol, glucose, Creatinine, Hct, thyroid function - X-ray- cardiac enlargement, aneurysms, signs of heart failure - C-reactive protein - ECG - stress testing - cardiac imaging - coronary arteriography