10 - Cardiovascular Pathology II Flashcards
Define ischemia
- Reversible cellular injury
- Therapeutic salvage may be possible
- No tissue death
Define infarction
- Irreversible injury
- Myofiber coagulative necrosis
- Once these fibers die, they don’t come back
What are the presenting factors in ischemic heart disease (IHD)?
- Angina pectoris
- Myocardial infarction
- Chronic IHD with heart failure
- Sudden cardiac death
How does IHD lead to heart failure?
Cardiac myocytes weaken, atrophy, leads to heart failure
What is myocardial ischemia?
- Insufficient oxygen supply to myocardial fibers
Is myocardial ischemia reversible?
Yes
What causes myocardia ischemia?
Decreased myocardial blood supply and/or Increased myocardial oxygen demand
There are three types of agina pectoris - what are they?
- Stable (typical) angina
- Unstable or crescendo angina
- Prinzmetal variant angina
Describe stable (typical) angina
- Most common form, produced by physical activity, emotional excitement, or any other cause of increased cardiac workload resulting in an imbalance in coronary perfusion relative to myocardial demand.
- Relieved by rest or administering nitroglycerin.
Describe unstable or crescendo angina
- Pattern of increasingly frequent pain, often of prolonged duration, that is precipitated by progressively lower levels of physical activity or that even occurs at rest.
- Caused by the disruption of an atherosclerotic plaque with superimposed partial thrombosis and possibly embolization or vasospasm (or both).
- Unstable angina thus serves as a warning that an acute MI may be imminent.
Example
- Sitting on the couch and you start getting chest pain
Describe prinzmetal variant angina
- Uncommon, episodic myocardial ischemia that is caused by coronary artery spasm.
- The anginal attacks are unrelated to physical activity, heart rate, or blood pressure.
- Responds promptly to vasodilators, such as nitroglycerin and calcium channel blockers.
What is the ABPI?
Ankle brachial pressure index
- Assesses risk of peripheral artery disease (blockage in arms/legs)
- Compares your blood pressure measured at your ankle with your blood pressure measured at your arm
What does ABPI tell you? What does a high ABPI tell you?
- An ABPI number below 0.9 can indicate calcification or narrowing/blockage of the arteries in your legs, leading to circulatory problems, heart disease or stroke.
How can ABPI be used as a predictor for mortality?
ABPI may be an independent predictor of mortality, as it reflects the burden of atherosclerosis
What is the most important form of IDH?
Myocardial infarction
How many people suffer from an MI annually in the US?
1.5 million
Nearly 10% of myocardial infarcts occur in people under age 40, and 45% occur in people under age 65. African Americans and whites are equally affected.
Are men or women at a higher risk?
Men
What contributes to the rising trend of MI in women?
- The decrease of estrogen following menopause is associated with rapid development of CAD, and IHD is the most common cause of death in elderly women
- Postmenopausal hormonal replacement therapy is not currently felt to protect against atherosclerosis and IHD
- Once you reach the age of 70, the rate of MI in men and women is equal
What are the symptoms of MI?
- Chest pain
- Dyspnea and diaphoresis (SOB and sweating)
- Weakness, light-headedness, nausea, vomiting, palpitations
- Loss of consciousness and sudden death
Describe the chest pain seen in MI
- Levine’s sign: clenching their fist over the sternum.
- Pain radiates most often to the left arm, but may also radiate to the lower jaw, neck, right arm, back, and epigastrium, where it may mimic heartburn.
- Diabetics can have “silent MI’s” due to neuropathy
= Very elderly do not usually have the typical presentation
How does an EKG change due to MI?
- ST segment depression or T wave inversion (suspicious for ischemia)
- ST segment elevation (indication of MI)
- Non-diagnostic or normal ECG (need to then check enzymes)
What are the two serum markers we look for?
- Troponin (from cardiac muscle)
- CK-MB (creatinine kinase)
Which enzyme will peak first?
Creatinine kinase (0-1 day)
Troponin (1-2 days)
What is the most important consideration for treating an MI?
TIMING TIMING TIMING
Why is timing so important?
- If you get to your patient in a half hour and you can reperfused the tissue, you have a chance of salvaging the myocardium and you can actually prevent any cell death
- If hours goes on and you don’t get to your patient, you will not be able to prevent an MI – cell death will occur
What determines the severity of an MI?
- The size of the vascular bed perfused by the obstructed vessels
- The duration of the occlusion
- The metabolic/oxygen needs of the myocardium at risk
- The extent of collateral blood vessels
- The presence, site, and severity of coronary arterial spasm
- Other factors, such as heart rate, cardiac rhythm, and blood oxygenation
What is the breakdown of arteries occluded in MIs?
- Left anterior descending coronary artery (40-50%)
- Right coronary artery (30-40%)
- Left circumflex (15-20%)
Describe a left anterior descending coronary artery MI
infarcts involving the anterior wall of left ventricle near the apex; the anterior portion of ventricular septum; and the apex circumferentially
Describe a right coronary artery MI
infarcts involving the inferior/posterior wall of left ventricle; posterior portion of ventricular septum; and the inferior/posterior right ventricular free wall in some cases
Describe a left circumflex artery MI
infarcts involving the lateral wall of left ventricle except at the apex
What will we see within 1/2 to 4 hours post MI?
Wavy red fibers (see slide 61 for image)
What will we see within 12-24 hours post MI?
Early coagulation necrosis
What will we see within 1-3 days post MI?
Peak neutrophil levels
What will we see within 3-7 days post MI?
Myocardial rupture
- All the mechanisms of wound healing have not occurred yet
- The actual site of the MI can rupture
KNOW THIS
What will we see after a couple months post MI?
Over a couple months, the wound healing will take over
Dense white tissue will form in the wall of the heart
List the possible complications following acute MI
- Contractile dysfunction
- Arrhythmias
- Myocardial rupture
- Pericarditis
- Right ventricular infarction
- Infarct extension
- Infarct expansion
- Mural thrombus
- Ventricular aneurysm
- Papillary muscle dysfunction or rupture
- Progressive late heart failure
What are the three types of myocardial rupture?
- Rupture of the free wall of the left ventricle
- Rupture of the papillary muscle
- Rupture of the ventricular septum
What does a rupture of the free wall of the left ventricle lead to?
Cardiac tamponade
Compression of the heart by an accumulation of fluid in the pericardial sac
What does a rupture of papillary muscle lead to?
Acute mitral valve incompetence
What does a rupture of the ventricular septum lead to?
Acutely acquired VSD (ventricular septal defect)
Eventually causes right heart failure
What is pericarditis?
Inflammation of the pericardium
- Occurs over time following an MI
- The area of the MI rubs against the pericardium causing inflammation
What is delayed Dressler’s syndrome?
- An autoimmune inflammatory reaction to myocardial neo-antigens that form as a result of an MI
- Typically occurs 2 weeks post-myocardial infarction (up to a few months)
What is a ventricular aneurysm?
- A complication occurring post-MI
- Arises from a patch of weakened tissue in a ventricular wall
- Balloon or bubble filled with blood pouches out
- Usually doesn’t burst, but can block blood flow out of the heart
What are some non-cardiac complications of MI?
- Acute pulmonary edema and congestion
- Hepatic congestion (acute and chronic)
- Splenic congestion
- Renal failure (congestive and/or ischemic)
- Systemic thrombo-embolism
- Cerebrovascular insufficiency (due to not pumping enough blood to take care of your brain)
What is the prognosis of a patient who has had an MI?
- 16% mortality within 30 days
- 5% mortality per year after that due to…
- 33% sudden death
- 33% re-infarction
- 33% CHF
Describe the etiology of coronary heart disease
Coronary heart disease is responsible for 1 in 5 deaths in the U.S.
- Massive killer
- Due to arthrosclerosis and coronary artery disease
What are therapeutic options for heart failure?
1 - Preventative measures 2 - Coronary care unit at hospital 3 - Thrombolytic therapy 4 - Stent placement 5 - CABG (coronary artery bypass graft)
What are the preventative measures?
- Diet
- Not smoking
- Blood pressure control
- Exercise
An ounce of prevention = a pound of
What is a thrombolytic therapy?
TPA
Give ASAP after occlusion to dissolve the clot
How many patients in the US have a CABG each year?
400,000
What do we make grafts out of?
- Reversed autologous saphenous vein
- Left internal mammary artery (the only artery in the body that isn’t affected by artherosclerosis)
How long does a saphenous vein graft last?
Long-term patency (openness) of saphenous vein grafts is only 50% at 10 years
How long a mammary artery graft last?
Greater than 90% of internal mammary artery grafts are patent (open) at 10 years.
