Ischemic Heart Disease Part 1 Flashcards
How many heart attcks are silent?
1 in 5
What is the most common serious chronic life-threatening illness in the US?
IHD
What are the most common risk factors for IHD?
- Genetic influences
- high-fat and energy-rich diet
- smoking
- sedentary lifestyle
In the US, IHD is growing among which groups?
Low-income
How is myocardial ischemia a supply and demand problem?
Myocardial ischemia results from an increase in demand with not enough supply
What generally causes myocardial ischemia?
- Imbalance between oxygen supply and demand
- Oxygen supply determined by blood flow
How is blood flow regulated?
Pressure vs resistance ratio
What is the most critical factor in the pathogenesis of myocardial ischemia? What impacts this?
- Radius of the blood vessel
- Atherosclerosis
- Vascular tone
- Endothelial cell dysfunction
What is prinzmetal angina?
Coronary vessels spasm
What is stable angina?
Plaque is walled off and not causing full blockage
What is unstable angina?
Haven’t completely clogged vessel, but have pain at rest
What is a myocardial infarction?
Complete blockage of the coronary vessel
What does acute coronary syndrome include?
Myocardial infarction and unstable angina
What causes ACS?
Plaque rupture and thrombus formation
What is an NSTEMI?
Partially impeded blood flow through coronary vessels
What is a STEMI?
Completely impeded blood flow through coronary vessels
What are characteristics of stable angina?
- Typical predictable pattern
- Occurs when heart under stress with higher O2 demand
- Typically lasts 15 mins
- Goes away with rest and/or NTG
- May continue without change for years
- Fixed stenosis
What are characteristics of unstable angina?
- Unexpected change in usual pattern of stable angina
- Blood flow to heart suddenly slowed by narrowed vessels or thrombus in coronary arteries
- May happen at rest and does not away
- Warning sign that MI is impending (EMERGENCY!)
- Due to formation and dissolution of thrombus
What are the 3 stages after occlusion of a coronary artery?
- Ischemia
- Injury
- Infarct
When happens with ischemia after occlusion of a coronary artery?
- Cardiac cells can tolerate mild-moderate anoxia for short time without impact on function
- Present as soon as decrease or absence of blood supply
- Cells return to normal when blood flow returns
What happens with injury after occlusion of a coronary artery
- Ischemia is severe or prolonged –> cardiac cells sustain damage and don’t function normally
- Damage to cells is reversible for some time
- Cells return to normal or near normal after return of blood flow
What happens during infarction after occlusions of a coronary artery?
*Complete absence of blood supply
* Anoxic cardiac cells sustain irreversible injury and die
What does irreversible myocardial injury result in during myocardial infarction?
Necrosis of a portion of the myocardium
What does it mean when someone says they had a acute MI?
<3-5 days old
What is a subendocardial/NSTEMI/Non-Q wave MI?
- Involves small area in subendocardial wall of LV, ventricular septum, or papillary muscle
- Caused by local decrease in blood from narrowing of coronary artery
- Subendocardial area particularly susceptible to ischemia
- EKG –> ST depression or T wave inversion
What is a transmural/STEMI/Q wave MI?
- Extends through whole thickness of heart muscle wall
- Associated with atherosclerotic plaques in a coronary artery that cause complete occlusion
- Labeled by wall involved (anterior, posterior, inferior, lateral, or septal)
- EKG –> STEMI –> Q Waves
What type of MI is more severe and has a high risk of complications?
Transmural/STEMI/Q Wave MI
What is a type I MI?
Spontaneous MI related to ischemia due to a primary coronary event such as plaque erosion and/or rupture, fissuring, or dissection
What is a type II MI?
MI secondary to ischemia due to either increased oxygen demand or decreased supply (ex coronary artery spasm, coronary embolism, anemia, arrhythmias, HTN, or hypotension)
What is a Type III MI?
Sudden unexpected cardiac death, including cardiac arrest, often with symptoms suggestive of myocardial ischemia
Death before blood samples could be obtained or at a time before the appearance of cardiac biomarkers in the blood
What is a Type 4 MI?
MI associated with coronary angioplasty or stents
What is a type 5 MI?
MI associated with CABG
What is silent ischemia?
Myocardial ischemia without discomfort or pain
Exact mechanism unknown
Who more commonly has silent ischemia?
- Diabetics
- Elderly patients
- Women
What is myocardial stunning?
- Reversible myocardial dysfunction following reperfusion of an ischemic insult
- Initially appears permanently damaged but following early reperfusion contractile function returns to normal
What is hibernating myocardium?
- Prolonged reduction in blood flow from coronary artery disease
- Causes ventricular contractile dysfunction that will improve once blood flow improves
What is the main artery that goes to the right side of the heart?
Right coronary artery
Which artery feeds the left ventricle?
Left anterior descending (anterior interventricular branch)
Which artery feeds the back side of the heart?
Posterior left ventricular branch and PDA
Which artery feeds the SA node?
SA nodal branch from circumflex branch
What vessels feed the right side of the heart?
Right coronary –> marginal and posterior descending
RaMP
If the RCA is blocked which portions of the myocardium will be affected?
Inferior wall LV and Right ventricle
What vessels feed the left side of the heart?
Left coronary –> circumflex and anterior descending
LoCA
What is the clinical significance of a inferior wall MI?
Often accompanied by a decrease in HR because of involvement of the sinus node. Long term effects usually less severe than anterior wall MI
What ECG leads correspond to a RCA block?
Goes to inferior wall and R ventricle so II, III, aVF (inferior leads)
If the PDA is blocked, what area of the myocardium would be affected?
Posterior wall
What leads would be impacted by a LAD block?
V1-V4
If the LAD is blocked, what areas of the myocardium would be affected?
Septal wall and anterior wall LV
What is the significance of a anterior wall LAD blockage impacting the anterior wall LV?
Anterior wall performs main pump function and decay of the function of this wall will lead to decreased BP, increased HR, shock, and HF long term
What area of the myocardium would be impacted by a left circumflex blockage?
Lateral wall LV
What ECG leads are impacted by a blockage in the left circumflex?
I, aVL, V5, V6
there is a chart on all of this if it is helpful
What are two questions to consider in initial evaluation of ischemic heart disease?
1) How likely is ACS
2) What is the risk of adverse events
What do we need to do when a patient presents with chest discomfort?
- A detailed history
- An appropriate, focused physical exam
- Consideration of patient risk factors
–> estimate the probability of signficiant CAD (high, intermediate, or low)
What term is used to describe chest discomfort related to IHD?
Angina pectoris
What is the typical cause of angina pectoris? What else could cause it?
- atherosclerosis
- anxiety
- PE
- pericarditis
- reflux
- muscle strain/costochondritis
- LVH
- aortic stenosis or regurgitation
What is the typical patient presentation of someone with a MI?
- Male >50 or female >60
- Episodic chest discomfort
How might someone describe the quality of a MI?
- Heavy
- Pressure
- Squeezing
- Smothering
- Aching
- Choking
Where is the pain due to an MI usually located?
- Substernal, central chest
- Radiation to arms/shoulders (left), neck, jaw, teeth, back/scapula, epigastrium
- Unlikely to radiate above mandible or below epigastrium
What is the timing usually for a MI?
- Sudden constant pain
What is the usual duration of chest discomfort with ischemic heart disease?
- 2-5 minutes
- Crescendo-decrescendo
What setting does chest discomfort usually occur in due to IHD?
exertion
What is the severity of chest discomfort with IHD?
varies and may not be correlated with extent of myocardial injury
What aggravating or alleviating factors may be present with IHD?
- Aggravating: activity/exercise, meals, stress/strong emotion, cold exposure, sexual activity, morning, supine position
- Alleviating: NTG, rest
What associated symptoms may be present in an MI patient?
- SOB
- N/V
- Diaphoresis
- Fatigue
- Weakness
- Feeling of impending doom
- Paresthesias
- Dizzy
- Fever
How might women experiencing an MI present?
- SOB
- Pressure or pain in the lower chest or upper abdomen
- Dizziness
- Extreme fatigue
- Lightheadedness
- Fainting
- Upper back pressure
What may be less accurate in women?
Exercise stress test
which population is more likely to die after their first heart attack?
Women
What will vital signs be like with an MI?
- Hypotension or HTN, tachycardia or bradycardia, nonspecific fever
Can also be normal
What general findings may be present in an MI PE?
- Anxious
- Restless
- Diaphoretic
- Pallor
- Confusion
What CV findings may be present during an MI PE?
- Arrhythmia
- Muffled heart sounds
- S4 gallop
- JVD
- New heart sounds/murmurs
- Diminished peripheral pulses
- Pericardial rub
What Pulm findings may be present during an MI PE?
- Pulmonary rales or wheezing
- Pulmonary edema
- Labored breathing if in LV failure
What should you look for on neuro exam of a suspected MI?
- Signs of altered levels of consciousness
- CVA
What is variant (Prinzmetal) angina?
- Results in vasospasm
- May occur at site of atherosclerosis or in normal vessels
- Often involves RCA
How is variant (Prinzmetal) angina treated?
- CCB and nitrates
Who most commonly has prinzmetal angina?
Middle-aged women
How will prinzmetal angina present on EKG?
mimics STEMI
What are other coronary artery associated causes of chest pain?
- Aortic dissection
- Coronary embolism
- Coronary arteritis
- Congenital abnormalities/anomalies
- Cocaine-induced vasospasm
What are non-coronary causes of myocardial O2 supply-demand mismatch?
- Hypotension
- HTN
- Hypertrophic CM
- Severe myocardial hypertrophy
- Severe AS/AR
- Pericarditis
- In response to increased metabolic demands (hyperthyroidism, anemia, paroxysmal tachyarrhythmias)
what are non-ischemic myocardial injury causes of chest pain?
- Myocarditis
- Non-ischemic cardiomyopathy
- Cardiac contusion
- Cardiotoxic drugs
- Multifactorial causes: Takotsubo, cardiomyopathy, PE, severe HF, sepsis
What conditions related to the pulmonary system can cause chest pain?
- Pulmonary embolus
- Pneumothorax
- Pneumonia
- Pleuritis
- Pulmonary HTN/cor pulmonale
What conditions related to the chest wall can cause chest pain?
- Costochondritis
- Fibrositis
- Rib fracture
- Sternoclavicular arthritis
- Herpes zoster
What conditions related to the GI system can cause chest pain?
- Esophageal: esophagitis, spasm, reflux, rupture
- Other: peptic ulcer, pancreatitis
- Biliary: colic, cholecystitis, choledocholithiasis, cholangitis
What psych conditions can cause chest pain?
- Anxiety disorders: hyperventilation, panic disorder, primary anxiety
- Affective disorders: depression
- Somatoform disorders
What diagnostic testing can be performed for a chest pain patient?
- Everyone gets EKG +/- cardiac biomarkers
- Stress testing
- Coronary angiogram
- Imaging
What sorts of stress tests can be performed?
- Exercise stress test alone
- Exercise stress test with nuclear imaging component
- Pharmacologic stress test with nuclear imaging
- Exercise stress test with imaging
What imaging studies can be performed for a chest pain patient?
- CT angiogram
- Echocardiogram (transthoracic and transesophageal)
- CT angiogram or V/Q scan to r/o PE
- Electron beam CT scan (for coronary calcification)
What is used to risk stratify patients to help determine who should undergo aggressive evaluation/treatment
TIMI (Thrombolysis in MI)
What are 7 components of a TIMI score?
- Aged >65 years
- > 3 CAD risk factors (HTN, DM, HLD, smoking, + FH early MI)
- Prior CAD (Stenosis >50%)
- Aspirin in last 7 days
- Severe angina (>2 anginal events within 24 hours)
- ST deviation on admission EKG (>.5 mm)
- Elevated cardiac markers (CK-MB or troponin)
How many points does a patient need to be low risk, intermediate risk, or high risk on TIMI score?
Low risk: 0-2
Intermediate risk: 3-4
High risk: 5+
What are components of the HEART score?
- History
- EKG
- Age
- Risk factors
- Troponin
What HEART score indicates that a patient should be discharged? Admitted for observation? Admit with early invasive strategies?
- 0-3 (risk of MACE - 2.5%)
- 4-6 (risk of MACE - 22.3%)
- 7-10 (risk of MACE - 72.7%)
What age is considered a score of 1 on HEART score? 2?
- between 45 and 64
- 65 or older
What is a score of 1 on the HEART score for risk factors? 2?
1 to 2 risk factors
3 or more risk factors
What is considered elevated troponin for a score of 1 on HEART score? 2?
- troponing <.04 is 0
- elevated 1-3 times discriminative +/- .04-.12 ng/ml
- elevated >3 times, discriminative, +/- accutroponin I >.12
What are risk factors for HEART score?
- BBB, LVH, digoxin effect, implanted right-ventricular pacemaker, past MI, +/- unchanged repolarization abnormalities
- DM, tobacco smoker, HTN, hypercholesterolemia, obesity, +/- family history of CAD
- Peripheral arterial disease, MI, past coronary revascularization procedure +/- stroke
