Coronary Artery Disease II Flashcards
Acute Coronary Syndrome (ACS)
a term used to describe a range of conditions associated with sudden, reduced BF to the heart
CAD branches into…
Stable Angina or Acute Coronary Syndromes (branches into Unstable Angina –> NSTEMI or STEMI)
When does STEMI occur?
occurs by developing a complete occlusion of a MAJOR coronary artery previously affected by atherosclerosis
this causes a full thickness damage of heart muscle
STEMI’s account for __% of myocardial infarction (MI; heart attacks)
70%
When does NSTEMI occur?
occurs by developing a COMPLETE occulsion of a MINOR coronary artery or a PARTIAL OCCLUSION of a MAJOR coronary artery previously affected by atherosclerosis
this causes a partial thickness damage of heart muscle
NSTEMI’s account for __% of MI
30%
Remember? Stable Angina results from…
- occlusion of the artery by a stable atherosclerotic plaque
- a stable atherosclerotic plaque > 70%
— autoregulation –>
arteriolar dilation occurs but is INSUFFICIENT to allow reserve coronary blood flow for exertion 6
In contrast, unstable angina (more stable) results from…
- an unstable atherosclerotic plaque
fatty streaks become fibrous plaques which ultimately advance to weakened plaques vulnerable to rupture
- can be <50% stenosis
What is a Fibrous Cap Rupture?
- due to shearing forces of blood flow
- ***Not all plaques rupture; “vulnerable plaques”
or “high risk plaques” include:
– large, lipid-rich core
– core consistency (i.e. less viscous)
– thin fibrous cap (less “protection”)
– increased inflammation in fibrous cap (post mortem studies found more macrophages in culprit lesions than in stable angina plaques)
Distinguish b/t Vulnerable & Stable Plaque
Vulnerable plaque - associated with unstable angina (can rupture)
- lipid core (larger)
- fibrous cap (smaller)
Stable plaque - associated with stable angina (won’t rupture with BF)
- lipid core (smaller)
- fibrous cap (larger
Types of clots –>
types of MI
White Clot
More PLATELETS than fibrin
INCOMPLETE artery occlusion
More common in NSTEMI
Red Clot
More FIBRIN than platelets
Usually COMPLETE artery occlusion
More common in STEMI
____ is much worse than ______
STEMI
NSTEMI
Unstable Angina
- platelet aggregation
- worse than stable angina
- not as bad as MI
ST-SEGMENT ELEVATION MI (STEMI)
- thrombosis
- completely occludes coronary artery
- thrombus is reddish (fibrin-rich)
(happen in bigger C.A)
NON-ST SEGMENT ELEVATION MI (NSTEMI)
- thrombosis does not occlude coronary artery (therefore smaller than STEMI)
- thrombus is grayish-white (platelet-rich)
- embolism blocks downstream microvascular artery
_____ thickness damage of heart muscle in NSTEMI
PARTIAL
_____ thickness damage of heart muscle in STEMI
FULL
(larger C.A. occulusion, lead to MI more severely can lead to HF even)
What are the Signs & Symptoms of ACS?
same as stable angina, except
* they can start to occur at rest (unstable angina)
* they do not get better with rest nor nitrates
What are the Symptoms of Unstable Angina?
PAIN
* often described as discomfort
* squeezing, pressure, burning, tightness, heavy weight on chest (elephant)
* Levine sign “fist in the center of the chest”
* gradual in onset; intensity increases over minutes (non-cardiac pain is usually the opposite)
Radiation of pain
* arms, shoulders, neck, jaw, back, throat, teeth, upper abdomen (C7-
T4)
* tend to have the same quality of chest discomfort with recurrent ischemic episodes (i.e. same location and intensity); increase in severity is a warning sign of unstable angina/acute coronary syndromes
Shortness of breath
* dysfunction of the heart leads to mild pulmonary congestion
Bradycardia
* slowheartrate<60bpm
* lesscommon
* blood supply to AV node impaired
Tachycardia
* stress/panic and release of catecholamines (to try and compensate for reduced oxygen supply)
Nausea/vomiting
* vagus nerve stimulation
Differentiating ACS
Stable Angina - resolves with rest, short duration
ACS - does not resolve with rest, severe pain, long duration
- STEMI (ST-segment elevation)
- Troponin T & CK (ST-segment depression, T wave inversion; therefore inactive MI or maybe had it before)
– NSTEMI (Trop T elevated (necrosis)
– Unstable Angina (Trop T normal (no necrosis)
Basically, is the ischemia enough to cause sufficient heart damage to release detectable amounts of troponin T?
What is Troponin?
- Complex of three regulatory proteins (troponins C, I & T)
- Integral to muscle contraction in cardiac & skeletal muscle (not smooth muscle)
- Two subtype isoforms (cardiac I and T) are VERY SENSITIVE AND SPECIFIC
indicators of damage to cardiac muscle
(associated with Ca2+)
What is Creatine Kinase (myocardial band)?
- Enzyme that facilitates transfer of high energy phosphate groups (via ATP and ADP)
- Found in skeletal muscle, cardiac muscle and the brain
- In muscle injury and when myocytes die, the muscle will release CK enzymes
(marker for muscle injury) - NOT SPECIFIC to cardiac muscle, so we no longer use CK-MB for cardiac
diagnostics
Necrosis:
cell membrane ruptures & cell content release into EC space & then ??
What is High-Sensitivity Troponin-T Test?
- Is a marker of CARDIAC MYOCYTE DEATH (dying heart cells)
- HIGH results indicate that there has been DAMAGE to the heart
- In emergency, this test is ordered at presentation and then every 8 hours until first positive result
When can levels of Troponin become elevated?
Levels of troponin can become elevated in the blood within 3 or 4 hours after heart injury and may remain elevated for 10 to 14 days. In people with angina, an elevated troponin may indicate that their condition is worsening and they are at increased risk of a heart attack.
Could you get increase of troponin levels in blood?
earlier point ???
What are the drugs used in ACS?
- relieve ischemia and ischemic pain
- disrupt or prevent further occlusion/clotting
- correct hemodynamic abnormalities (blood pressure, atherosclerosis)
What are the drugs used for management of ACS?
Morphine - Pain relief
Nitrates - Ischemia relief
Aspirin - Prevent clotting
Beta-blockers - Ischemia relief
Thienopyridines (clopidogrel,
prasugrel) or
ticagrelor - Prevent clotting
GP IIb/IIIa inhibitors - Prevent clotting
Heparin - Prevent clotting
Fibrinolytics - Break up clots (tenectoplase,
alteplase)
Statins (once stable) - Lower cholesterol
ACEIs (once BP stable) - BP control/prevent future events
Slide 26 & 28
done
TIMI Risk Scores (US/NSTEMI)
One Point awarded for each of the following:
- Age ≥ 65 years
- 3 or more of the following heart disease risk factors:
– Smoking
– Hypercholesterolemia
– Hypertension
– Diabetes
– Family history of premature cardiovascular
events/death
- Known coronary artery disease (≥50% stenosis)
- ASA use in past 7 days
- ≥2 episodes of chest discomfort in the past 24 hours
- ST-segment depression ≥0.5mm (on ECG)
- Positive biochemical marker for infarction
What is considered Low Risk for TIMI?
0-2 points
0-8.3% risk of death/MI or severe ischemia
What is considered Moderate Risk for TIMI?
3-4 points
13.2-19.9% risk of death/MI or severe ischemia
What is considered High Risk for TIMI?
5-7 points
26.2-40.9% risk of death/MI or severe ischemia
What is the Reperfusion Therapy?
ST-SEGMENT ELEVATION MI
* thrombosis
* completely occludes coronary artery
* thrombus is reddish (fibrin-rich)
- mechanically disrupt clot – PCI (mech. way)
- dissolve clot – thrombolytics (aka fibrinolytics)
eg. streptokinase, alteplase, tenecteplase, reteplase (pharmacological way)
What is Angiography (or coronary angiogram)?
A catheter is inserted through artery in forearm, thigh, upper groin or neck and threaded to the coronary artery in question
A dye is released, allowing for X-rays to illuminate the arteries and show areas of poor blood flow
What is a Percutaneous Coronary Intervention?
A tiny catheter runs from the femoral artery (or jugular vein depending on side of heart) to the affected area
A balloon at the tip squashes the atherosclerotic plaque and holds the artery open
A bare-metal or drug eluting stent is placed, like a little cage to keep the artery open
- b/c otherwise it’ll close after taking it out (so stent stays in; therefore this will cause it to narrow again)
will leave a scar which will affect heart function after the procedure ??
What is Coronary Revascularization (Bypass)?
- Harvest a blood vessel (great saphenous vein, left internal mammary artery (LIMA))
- Sew one end of the vessel above the blocked coronary artery and one end below “by-passing” the blockage to restore blood flow
- The number of blockages determine how many bypasses need to be done
(i.e. triple, quadruple, quintuple)
What is the Graded Severity of Stable Angina?
less severe
- triggered by activities that increase myocardial oxygen demand and lasts for 2-5 minutes
- described as discomfort rather than pain
What is the Graded Severity of Unstable Angina?
At least 1 of these features:
* occurs at rest (or minimal exertion) and lasts for more than 20 minutes
* severe and described as frank pain of new onset (i.e. within 1 month)
* occurs with a new pattern – more severe, prolonged, or occurs with less exertion than previous angina
ischemia IS NOT severe enough to produce myocardial necrosis so there is no release of biochemical markers (eg. troponins T or I, creatine kinase (CK) myocardial band)
What is the order of Graded Severity for CAD?
Stable Angina < Unstable Angina < Myocardial Infraction < NSTEMI < STEMI
What is the least and most stable CAD?
stable angina
STEMI
____% of patients with myocardial infarction die before they can reach the hospital
33-50%
What is a major reason why 33-50% of patients with myocardial infarction die before they can reach the hospital
Lethal arrhythmia –> Sudden cardiac death
How many cardiomyocytes in heart?
24% –> cardiomyoctes are huge
SA node has highest signal, it can inhibit in AV node
Cardiac arrhythmia:
refers to a group of conditions that cause the heart to beat irregular, too slowly, or too quickly.
(heart no longer beats normally)
What are the types of Cardiac arrhythmia’s?
- Tachycardia - >100
- Bradycardia - < 60
- Irregular heartbeat, also known as a flutter or fibrillation
- Early heartbeat, or a premature contraction
Tachycardia:
This refers to a fast heartbeat — a resting heart rate greater than 100 beats a minute.
- Tachycardias in the atria
- Tachycardias in the ventricles
What are Tachycardias in the atria?
- Atrial flutter
- Atrial fibrillation
- Supraventricular tachycardia (SVT)
Atrial flutter:
is caused by a re-entry circuit within the right atrium. The length of the re-entry circuit corresponds to the size of the right atrium, resulting in a fairly predictable atrial rate of around 300 bpm (range 200-400).
If one signal impulse is high enough it’ll lead to re-entry
NOT P wave (replaced normal P wave)
Atrial Fibrillation:
A rapid heart rate caused by chaotic electrical impulses in the atria. These signals result in rapid, uncoordinated, weak contractions of the atria
- many impulses (fire at diff. positions & strength)
Supraventricular tachycardia (SVT):
is usually caused when electrical impulses originating at or above the atrioventricular node, or AV node are out of synch.
- happen above or at AV node
(NO P wave at all)
Tachycardias in the ventricles:
Ventricular tachycardia
Ventricular fibrillation
Long QT syndrome
Ventricular fibrillation:
Ventricular fibrillation occurs when rapid, chaotic electrical impulses cause the ventricles to quiver ineffectively instead of pumping necessary blood to the body. This serious problem is fatal if the heart isn’t restored to a normal rhythm within minutes.
Long QT syndrome:
Long QT syndrome is a heart disorder that carries an increased risk of fast, chaotic heartbeats.
Ventricular tachycardia:
is a rapid, regular heart rate that originates with abnormal electrical signals in the ventricles. The rapid heart rate doesn’t allow the ventricles to fill and contract efficiently to pump enough blood to the body.
(reversibel (abnormal impulse in ventricle)
Ventricular fibrillation:
occurs when rapid, chaotic electrical impulses cause the ventricles to quiver ineffectively instead of pumping necessary blood to the body. This serious problem is fatal if the heart isn’t restored to a normal rhythm within minutes.
- more severe (will flatline mostly likely in next few)
- no regular wavelength at all (fire at diff. times & strength)
The long QT syndrome (LQTS):
is a disorder of myocardial repolarization characterized by a prolonged QT interval on the electrocardiogram (ECG). It is often inherited and present from birth. It can also be caused by certain medications.
The long QT syndrome (LQTS) symptoms may include:
- Fainting
- Dizziness
- Seizures
- Abnormal rate and rhythm of the heartbeat
Bradycardia:
This refers to a slow heartbeat — a resting heart rate less than 60 beats a minute
What are the Bradycardia disorders?
Sick sinus syndrome
Conduction block
Sick sinus syndrome:
Sinus node isn’t sending impulses properly and the heart rate may be slow (bradycardia).
Conduction block:
A block occurs along the electrical transduction pathways, often in or near the AV node.
What is a major treatment of Bradycardia?
Pacemaker
Bradycardia is…
normal waves but just slow
