18 Alterations in Cardiac Function Flashcards
Coronary Heart Disease [CHD]
common names
Ischemic Heart Disease
Coronary Artery Disease [CAD]
Coronary Heart Disease [CHD]
-characterized by insufficient delivery of oxygenated blood to the myocardium due to atherosclerotic coronary arteries
sequelae
a condition which is the consequence of a previous disease or injury
Coronary Heart Disease [CHD]
sequelae
1 Angina Pectoris (3 types, myocardial infarction)
2 Dysrhythmias
3 Heart failure
4 Sudden cardiac death
Coronary Heart Disease [CHD]
risk factors
atherosclerosis-main cause
microcirculation abnormalities
how does atherosclerosis lead to cardiac ischemia/CHD
narrowing of arterial lumen can lead to thrombus formation, coronary vasospasm, endothelial cell dysfunction
vulnerable plaques vs stable plaques
V: large lipid core, thin cap, high shear stress
S: more collagen + fibrin, stable cap
vulnerable plaques may rupture and erode which stimulates…
clot formation on the plaque
Ischemia
oxygen supply is insufficient to meet metabolic demands
critical factors in meeting cellular demands for oxygen
1 rate of coronary perfusion
2 myocardial workload
coronary perfusion can be altered by
1 large, stable atherosclerotic plaque
2 acute platelet aggregation + thrombosis
3 vasospasm
4 failure of autoregulation by microcirculation
5 poor perfusion pressure
chronic occlusion of a coronary vessel leads to…
STABLE ANGINA
acute occlusion leads to
plaque disruption + thrombus formation
-results in UNSTABLE ANGINA or MI
Angina Pectoris
chest pain associated w intermittent myocardial ischemia
-no permanent myocardial damage occurs
Angina Pectoris
symptoms
burning, crushing, squeezing, choking or referred pain
Angina Pectoris may result in…
inefficient cardiac pumping w resultant pulmonary congestion + shortness of breath
myocardial ischemia may UNCOMMONLY be caused by…
1 coronary vasospasm
[PRINZMETAL or VARIANT ANGINA]
2 hypoxemia
3 low perfusion pressure fr vol depletion or shock
3 types of angina
Stable Angina (stable or typical or classic)
Unstable Angina
Prinzmetal or Variant Angina
Stable or Typical or Classic Angina
- most common
- characterized by stenotic atherosclerotic coronary vessels
Stable or Typical or Classic Angina
onset + treatment
- onset of anginal pain is generally predictable + elicited by similar stimuli each time
- relived by rest + nitroglycerin
Unstable or Crescendo Angina
- 1 of 3 types of Acute Coronary Syndrome
- similar to Stable Angino but NO RELIEF W/O MEDICAL HELP
- may progress to acute ischemia
Prinzmetal or Variant Angina
-unpredictable attacks of anginal pain
characterized by:
- vasospasm,
- atherosclerosis-induced hypercontractility,
- abnormal secretion of vasospastic chem by local mast cells,
- abnormal Ca flux across vascular smooth muscle
Prinzmetal or Variant Angina
onset
- onset of symptoms is UNRELATED to phys or emo exertion, heart rate, or other obvious causes of increased myocardial oxygen demand
- UNPREDICTABLE
Acute Coronary Syndrome
3 types; 1 is unstable angina
-caused by plaque rupture w acute thrombus dvlpt
Acute Coronary Syndrome
signs + symptoms
chest pain usually more severe, last longer than 15 mins, may radiate to limbs, jaw, back
- nausea, vomiting, diaphoresis, shortness of breath
- not relieved by rest or nitroglycerin
- in unstable angina: occlusion is partial
- in MI: occlusion is complete
Asymptomatic/Silent MI
- women, elderly, + patients w neuropathies
- atypical symptoms like fatigue, nausea, back pain, + abdominal discomfort
Acute Coronary Syndrome
diagnosis
must have 2 out of 3
1 S/S
2 electrocardiographic changes [ECG]
3 Biomarkers (elevation of spec. marker proteins in blood)
acute occlusion causes a range of cellular events depending on…
- availability + adequacy of collateral blood flow
- relative workload
- length of time that flow is interrupted
ultimate size of infarcted tissue depends on…
extent
duration
severity of ischemia
Acute Coronary Syndrome
histology
18-24 hrs: DEC BF: area of infarction becomes paler than surround ing tissues
5-7 days: NECROSIS/GANGRENE: turns yellow w soft rim of red vascular connectv tissue
1-2 wks: CLEARNCE: necrotic tissue degraded + cleared away; infarcted myocardium weakened + susceptible to rupture
<6wks: REPAIRMNT: necrotic tissue replaced by tough fibrous scar tissue
Acute Coronary Syndrome
Serum Marker Changes for diagnosis
- intracellular becomes extracellular
- myoglobin, troponin, lactate dehydrogenase, + creatine kinase
- increased CK-MB + TROPONIN I + T
Acute Coronary Syndrome
ECG changes for diagnosis
1 ST-segment elevation
2 large Q waves
3 inverted T waved
ST-segment elevation for Acute Coronary Syndrome
STEMI: patients w chest pain + evidence of acute ischemia on ECG
NON-STEMI/NSTEMI: patients presenting symptoms of unstable angina + NO ST elevation on ECG
treatments for 2 types of ST-segment elevations
STEMI: candidates for ACUTE REPERFUSION THERAPY
NSTEMI: candidates for ANTIPLATELET DRUGS
MI leads to drop in CO which triggers…
compensatory response
Sympathetic nervous sytm activation leads to__ by__
leads to increased myocardial workload by increasing
heart rate,
contractility,
BP
Acute Coronary Syndrome
treatment principals
1 decreasing myocardial oxygen demand
2 increasing myocardial oxygen supply
3 monitor + manage complications [SNS activation]
decreasing myocardial oxygen demand for treating ACS
- sympathetic antagonist,
- rest,
- heart rate control,
- pain relief,
- afterload reduction
increasing myocardial oxygen supply for treating ACS
- thrombolysis,
- angioplasty,
- coronary bypass grafting
monitor + manage complications [SNS activation] for treating ACS
- early detection + mgmt of dysrhythmias + conduction disorders
- continuous ECG monitoring
clinical treatments for ACS
Morphine: pain (+dec O2 demand)
Oxygen: ischemia
Nitroglycerin: ischemia
Anticoagulants: ischemia (platelet thinner or thrombolysis)
Stenosis**
failure of the valve to open completely
-results in extra pressure work for the heart
Regurgitation (Insufficiency)*****
inability of a valve to close completely
-results in extra volume work for the heart
Valvular Disease
congestion upstream + low blood supply downstream
2 types: stenosis + regurgitation
Valvular Disease
clinical manifestations
- murmrs are common
- heart failure S/S
myocardial infarction biomarkers of choice**
troponin I + T
