CARDIAC LECTURE 1: Epidemiology & coronary heart disease Flashcards
Cardiac disease is the ____ cause of death in Canada
2nd
What is the most common type of heart disease in Canada?
Ischemic
What are 5 causes of heart disease?
- Rupture
- Obstruction
- Improper flow (backward, diverted)
- Failure to pump (contraction, emptying, relaxing)
- Conduction defect
What is the general term for diseases where insufficiency of oxygen leads to damage of the myocardium?
Coronary heart disease
What are 2 ways cardiac myocytes initially adapt to hypoxia?
- Generates anastomoses to bypass blockage
- Vasodilation
At what point are the effects of CHD felt?
When the vessel is about 70% occluded
What are 2 main consequences of ATP depletion in a hypoxic state?
- Na+/K+ pump cannot work, causing influx of Na+ and fluid (swelling)
- Anaerobic metabolism, causing acidity
What are 3 other consequences of ATP depletion in a hypoxic state?
- Ribosome detachment
- Decreased protein synthesis
- Lipid deposition
What is the mechanism behind angina?
Injured cells release chemicals that activate nociceptors
Why is anginal pain often felt at other places than the heart?
Referred pain: Sensations from upper abdomen, shoulders, arms, neck, lower jaw travel along same pathways and enter spinal cord at same region
What are 3 patterns of angina?
- Stable angina
- Vasospastic angina
- Unstable/crescendo angina
What kind of angina normally manifests when cardiac workload is increased, and reduces at rest?
Stable angina
What is the mechanism behind stable angina?
Stenotic/atherosclerotic coronary vessels dilate poorly in response to increased demand
What kind of angina is characterized by unpredictable attacks, predominantly at rest?
Vasospastic (Prinzmetal, variant) angina
What are 3 possible mechanisms behind vasospastic angina?
- Vascular smooth muscle hyperreactivity
- ANS imbalance
- Endothelial dysfunction
What are 2 treatments for vasospastic angina?
- CCBs
- Nitro
What kind of angina is characterized by increasingly frequent pain with progressively less exertion?
Unstable/crescendo angina
What is the mechanism behind unstable angina?
Stenotic coronary artery is further blocked by a ruptured plaque or embolism and leads to a severe obstruction
What are 2 possible outcomes for unstable angina?
- Clot dissolves before myocardial tissue dies
- Myocardial infarction
What is the term for necrossi of cardiac muscle due to prolonged ischemia?
Myocardial infarction
How long until ischemia leads to irreversible changes/necrosis?
20-30 minutes
Why may the outside of the heart appear healthy despite necrosis occuring?
The epicardium is affected last by MI
Which layer of the heart feels the effects of MI the most, and why?
Endocardium, as it is the farthest away from the blood supply
What is the term for the plasma membrane of cardiomyocytes?
Sarcolemma
What morphological changes occur in the heart after 6 hours post MI?
Coagulative necrosis
What is the eventual end result of the necrotic area of the heart?
Becomes scar tissue
What are 4 atypical symptoms of MI that may occur in females?
- Breathlessness
- Sweating
- Nausea/vomiting
- Anxiety, tireness
On an ECG strip, where is the ST segment located?
The flat portion right after the peak (R)
What are 2 ECG readings that are considered NSTEMI?
- ST depression
- T inversion
What is the treatment for ST elevation MI?
Immediate reperfusion therapy
What is the treatment for non-ST elevation MI?
Antiplatelet and anticoagulation therapy
What is the best serum biomarker used to diagnose MI?
Troponin I and T
How long does it take for troponin to build up in the blood?
A few hours
How long will troponin levels remain elevated after MI?
Up to 2 weeks
What are 3 other biomarkers used to diagnose MI?
- Creatine kinase
- Myoglobin
- Lactate dehydrogenase
What are the 5 steps in diagnosing MI?
- Presentation
- Working diagnosis (ACS)
- ECG
- Cardiac biomarkers
- Final diagnosis
The patient’s ECG shows ST elevation, and they have positive biomarkers. What is the diagnosis?
STEMI
The patient’s ECG does not have ST elevation, and their biomarkers are negative. What is the diagnosis?
Unstable angina
The patient’s ECG does not have ST elevation, but their biomarkers are positive. What is the diagnosis?
NSTEMI
What are 3 methods of immediate reperfusion treatment?
- Percutaneous coronary intervention (PCI)
- Fibrinolysis (clot busters)
- Coronary artery bypass graft (CABG)
What are possible consequences due to reperfusion?
- Hemorrhage
- Arrhythmias
- Inflammation
What histological changes may be observable in cardiac muscle tissue after reperfusion?
Contraction bands
What is the underlying cause for arrhythmias following MI?
Dead cells block conduction pathways
What would cause a patient to experience cardiogenic shock following MI?
A large region of the muscle in the left ventricle is destroyed
What is the underlying cause for myocardial rupture following MI?
Damaged tissue is weakened until scar tissue forms
What is the term for a complication of MI where there is underlying myocardial inflammation leading to scarring?
Pericarditis
What is the term for a complication of MI where new necrosis develops next to the area of infarction?
Infarct extension
What is the term for a complication of MI where weakness in the affected tissue leads to stretching, thinning, and dilation?
Infarct expansion
What is the term for a complication of MI where thing scar tissue of the ventricular wall bulges with contraction?
Ventricular aneurysm
Why is mural thrombus a possible complication following MI?
- Abnormal contractility causes stasis
- Damage to endocardium creates a thrombogenic surface
Which muscles of the ventricles may experience dysfunction following MI, and what may this lead to?
Papillary muscles
Lead to rupture and mitral valve regurgitation
What is the term for unexpected death from cardiac causes, within 1 hour of onset of symptoms?
Sudden cardiac arrest/death
What is the underlying cause of suddent cardiac death?
Ischemia produces V-fib
What is the term for progressive heart failure caused by slow atrophy and death of cardiomyocytes from chronic ischemia?
Chronic ischemic cardiomyopathy
How is chronic ischemic cardiomyopathy different from MI?
Dead cells are spread throughout the heart instead of localized