Pathology of the Cardiovascular System 1 Flashcards
Atherosclerosis
the process of narrowing within the arteries due to a buildup of fatty plaques over time
Atheroma
fatty plaque deposits consisting of an outer firm shell with a soft inner fatty core.
Ischaemic heart disease
When the coronary arteries become narrowed, blood flow and oxygen supply to the myocardium is reduced
Ischaemia
inadequate blood supply
Chest pain resulting from ischeamic heart disease
angina
Most common symptoms of stable angina
pain or a feeling of discomfort or tightness in the chest, which can often spread to the jaw, back, shoulders and arms
The pain is usually worse on exertion / stress (myocardial demand is higher in these conditions and the heart does not receive enough blood) and relieved after a few minutes on resting.
Shortness of breath is also a common symptom
Risk Factors for IHD:
- Diabetes
- Family history
- High cholesterol
- High blood pressure
- High blood triglycerides
- Obesity
- Physical inactivity
- Smoking
Ischemic heart disease can lead to:
Chronic Angina
myocardial Infarction
congestive heart failure
arrhythmia
Thrombosis
Arteries can become narrower at some locations due to build-up of cholesterol rich deposits
Blood flow can become compromised due to obstructions (plaque) in the lumen of blood vessel
Plaque build up leads to…
Reduced diameter = increased resistance = reduced blood flow in vessel = increases velocity = reduces pressure at the location of the plaque
Can lead to angina/heart attack if occurs in blood vessels leading to heart
Atherosclerosis
is the hardening and thickening of the walls of the arteries
Thrombus
a cellular mass formed within the blood vessel. Composed of platelets, red blood cells, neutrophils and lymphocytes, held together by fibrin derived from the coagulation pathway
Major precipitating event in arterial thrombosis…
Platelet activation at the sites of atherosclerotic plaques
Plaque rupture leads to…
acute thrombosis → acute artery occlusion → tissue death → organ failure → death
Atherosclerotic plaques form due to…
build-up of lipids
If an atherosclerotic plaque ruptures…
thrombus forms which blocks the circulation of blood
Atherosclerosis is a…
progressive disease
Thrombosis =
formation of a blood clot
Thrombosis can lead to…
sudden block of coronary blood supply = heart attack
Over several years a plaque can grow…
obstructs artery which may mean that exercise may result in chest pain = stable angina
The plaque can spontaneously rupture…
the blood system tries to cover up the rupture by sending platelets and coagulation factors → thrombus forms…
the thrombus can cause occlusion of the remaining lumen.
If this occlusion is partial = episode of chest pain (can lead to small heart attack).
Full block = full heart attack.
Myocardial ischaemia…
Lack of blood flow to the heart muscle
no supply of metabolites
loss of oxygen
ATP depletion
loss of calcium homeostasis
calcium concentration becomes high inside cardiac cells
muscle cell cross-bridges remain bound so relaxation cannot occur = they contract to a point where the membrane ruptures and cell death occurs
Overtime this leads to…Cell death
Eventually… Tissue death = area of “infarction”
This leads to… Heart failure
After ischeamia…
Cells can recover with reperfusion depending on how long ischemia took place for
Most common cause of myocardial ischeamia…
the block of the coronary artery (artery that supplied blood to the heart tissue).
Treatment of myocardial ischeamia…
remove the blockage using drugs or Balloon Angioplasty
when the ischemia ends there is reperfusion of tissue that was previously ischemic – however, reperfusion can actually cause further cell damage
At rest, patients with stable angina often have a ……….. ECG
normal
To see signs of myocardial ischeamia on an ECG….
use exercise testing
Treatment for Stable Angina:
A short acting nitrate (GTN spray)
Beta-blocker or calcium channel blocker
Aspirin
Statin
Ace Inhibitor (for those with diabetes)
Anti-hypertensive medication
Prinzmetal’s angina
a form of chest pain, pressure, or tightness caused by spasms in the arteries that supply blood to the heart
a form of unstable angina
Prinzmetal’s angina occurs…
at rest, in contrast to stable angina which usually occurs in a predictable pattern during exertion or exercise.
Symptoms usually occur in clusters, with periods of frequent episodes lasting for a few months followed by weeks or months with no chest pain episodes
The exact cause is unknown, but patients normally have atherosclerosis
The chest pain caused by Prinzmetal’s angina is caused by…
coronary artery spasm (involuntary constriction of the muscle in the artery) which markedly reduces the size of the vessel lumen and restricts blood supply to the myocardium
ECG of Prinzmetal’s angina shows…
ST elevation at the time of symptoms
Unstable angina, Non-STEMI and STEMI all result from…
complete or almost complete thrombotic occlusion of a coronary artery following rupture of an atherosclerotic plaque
NSTEMI and Unstable angina usually result from…
incomplete occlusion of a coronary artery
STEMI is associated with…
complete occlusionof a coronary artery
Unstable angina is …
Unstable angina is a type of chest pain that often doesn’t have a pattern and usually gets worse. Will likely lead to a heart attack.
It happens with only mild physical activity or may happen without warning when you’re at rest, relaxing or even asleep.
Most common cause of unstable angina…
Coronary artery disease due to atherosclerosis
Atherosclerosis is the buildup of fatty material, called plaque, along the walls of the arteries. This causes arteries to become narrowed and less flexible. The narrowing can reduce blood flow to the heart, causing chest pain.
Unstable angina treatments may include:
- Medicines to help blood clots dissolve and stop new blood clots from forming.
- Angioplasty with stent implantation.
- Heart bypass surgery.
Stable angina
- Occurs with physical activity or with anger, anxiety or stress.
- Lasts a short amount of time (usually only a few minutes).
- Occurs regularly or predictably — usually with the same amount of activity or emotional stress every time.
Acute coronary syndrome:
An umbrella term encompassing:
o STEMI
o NSTEMI
STEMI =
ST ELEVATION MYOCARDIAL INFARCTION
NSTEMI =
NON-ST ELEVATION MYOCARDIAL INFARCTION
Myocardial infarction
term used to describe death (necrosis) of heart muscle as a result of prolonged severe lack of oxygen (ischaemia).
Acute coronary syndrome pain…
may be similar to a bout of normal (stable) angina, but it is usually more severe and lasts longer (usually lasts more than 15 minutes - sometimes several hours).
ECG changes associated with unstable angina and NSTEMI…
ST depression at rest with or without T wave inversion
Subendocardial (partial thickness) injury
= ST depression
ST elevation is not seen with NSTEMI as the coronary thrombus is not completely occlusive and injury is limited to the subendocardial layers only
Transmural (full thickness) injury
A completely occlusive thrombus causes full-thickness (transmural) myocardial injury.
This leads to ST elevation and Q wave formation.
Pathological Q waves
Q waves form when myocardial tissue that has undergone transmural injury becomes stunned or scarred. The tissue becomes electrically inert (inactive) and actually acts as a window through to the myocardium on the opposite side of the ventricle. The electrical activity in the opposite wall will be traveling away from the leads looking at the infarcted zone. This means that the opposing R wave which would be seen through the window, is instead represented as a Q wave.
Not normally seen in NSTEMI or Unstable Angina (only STEMI)
Treatment for a STEMI
stent balloon angioplasty
Angiotensin-converting enzyme (ACE) Inhibitors
relax the blood vessels and lower blood pressure (e.g. Ramipril)
Anti-platelet medication
e.g. Aspirin or Clopidogrel to reduce the chances of blood clots forming
Beta-blockers
lower heart rate (e.g. bisoprolol)
Nitrates
dilate the blood vessels
Heart failure
heart does not pump blood around the body as well as it should
systolic heart failure
reduced cardiac contractility (weakened heart muscle)
diastolic heart failure
impaired cardiac relaxation and abnormal ventricular filling (stiff heart muscle)
oedema
When blood does not move efficiently through the circulatory system it starts to back up, increasing the pressure in the blood vessels and forcing fluid from the blood vessels into body tissues.
When the left ventricle starts to fail…
fluid collects in the lungs leading to pulmonary congestion. Breathing becomes more difficult and the person may feel short of breath, particularly with activity or when lying down.
When the right ventricle starts to fail…
fluid begins to collect in the lower legs. As the condition worsens, the abdomen collects fluid (ascites).
Congestive HF Symptoms:
- Fatigue
- Reduced exercise capacity
- Shortness of breath
- Oedema
Congestive HF causes:
- Viral Cardiomyopathy
- Ischaemic cardiomyopathy
- Alcoholic cardiomyopathy
- Valvular heart disease
- Hypertensive heart disease
- Prolonged arrhythmia
Treatment for Congestive HF:
- Diuretic medications may be prescribed to try to decrease fluid within the body so that the heart does not have to work as hard to circulate blood through the blood vessels in the body.
- ACE inhibitors (angiotensin-converting enzyme inhibitors) and ARBs (angiotensin receptor blockers) decrease systemic resistance and lowering the strain on the heart.
- Beta blockers may control heart rate and increase cardiac output and ejection fraction.
Chronic Heart Failure
an inability to maintain adequate tissue perfusion at a normal filling pressure = in order to get enough force being generated it requires a higher filling pressure (end-diastolic pressure).
Often get remodelling of the heart but over a period of time that remodelling fails to maintain cardiac output.
Common causes of LV Heart Failure:
o Reduced muscle mass following a myocardial Infarct (e.g. caused by myocardial ischemia)
o Excessive workload from systemic hypertension (high blood pressure), valve disease
LV heart failure results in…
o Impaired stroke volume resulting from abnormal Ca-regulation and electrical activity = “Systolic Heart Failure”
o Impaired ventricular filling can also occur = “Diastolic Heart Failure”
o Patients with Heart Failure are nearly 10-times as likely to suffer a Sudden Cardiac Death due to lethal cardiac arrhythmia (VT/VF)
Delayed after-depolarisations
Arrythmias such as VT are triggered by Delayed after-depolarisations (DADs) = depolarisations that occur during diastole (between contractions) often associated with spontaneous or unsynchronised calcium release events.
Patients with HF commonly develop…
polymorphic ventricular tachycardias which can degenerate into ventricular fibrillation – an ICD (defibrillator) shock is required for the heart to go back into normal sinus rhythm (without defibrillation the patient is likely to die).
Hypertension is a major risk factor for…
ischaemic and haemorrhagic stroke, myocardial infarction, heart failure, chronic kidney disease, cognitive decline and premature death
Stage 1 hypertension
average blood pressure is 135/85 mmHg or higher
Stage 2 hypertension
average blood pressure is 150/95 mmHg or higher
Severe hypertension
systolic blood pressure is 180mmHg or higher
diastolic blood pressure is 110 mmHg or higher
Cause of primary hypertension:
due to lifestyle and genetic factors. Lifestyle factors include too much salt in the diet, not enough exercise, obesity and alcohol consumption.
Cause of secondary hypertension
high blood pressure secondary to an existing condition such as narrowing of the kidney arteries, endocrine disorders
Treatment of hypertension:
Lifesyle changes
Medical treatment usually includes ace-inhibitors, angiotensin receptor blockers or calcium channel blockers or a combination
The chronic elevation of pulmonary vascular resistance can result in:
- Right Ventricle (RV) tries to compensate by increasing wall thickness = RV hypertrophy
- RV tries to get stronger to be able to push that blood to the lungs
- This leads to less room in the ventricle
- RV enlargement (to accommodate all the blood) = RV dilatation
- Tricuspid annulus dilatation (tricuspid valve is unable to close properly)
- Valve leaks backwards into the right atrium
- Extra blood in the right atrium (blood from all the body + coming from the leaking)
- Right atrial enlargement
Right atrial enlargement produces…
a peaked P wave (P pulmonale) with amplitude:
> 2.5 mm in the inferior leads (II, III and AVF)
> 1.5 mm in V1 and V2
The principal cause of atrial enlargement is….
pulmonary hypertension due to:
* Chronic lung disease (cor pulmonale)
* Tricuspid stenosis
* Congenital heart disease (pulmonary stenosis, Tetralogy of Fallot)
* Primary pulmonary hypertension
Common causes of chronic heart failure:
Ischeamic heart disease
Valvular heart disease (aortic stenosis)
Hypertension (causes left ventricular hypertrophy leading to heart becoming stiff)
Arrhythmia (AF)
Congestive heart failure:
The heart is not able to efficiently pump an adequate volume of blood to body, fluid begins to back up within the circulation and fluid builds up in lungs/alveoli = pulmonary oedema
MI leads to…
Dead tissue = stiff tissue = doesn’t contracts and relax properly
Angina is described as stable…
Symptoms relive on rest or with GTN spary
Angina is described as unstable…
When symptoms come randomly at rest
GTN spray
Glyceryl trinitrate
Causes vasodilation
Acute coronary syndrome =
A spectrum of conditions resulting from thrombus formation in the coronary arteries following rupture of an atherosclerotic plaque
- Unstable angina
- NSTEMI
- STEMI
Unstable angina =
Myocardial cells are ischeamic but not yet necrotic (no cell death has occurred)
NSTEMI =
Partial death of myocardial cells (only extends through a portion of the wall)
No ST elevation
STEMI =
Complete occlusion of coronary artery = death of cardiac cells extends across whole thickness of the heart wall
New LBBB
can also suggest STEMI
to see posterior STEMI
V7
V8
V9
Isolated T waves are
Post ischemic
T wave inversions alongside ST depression
Indicates ongoing ischemia (NSTEMI or unstable angina)
Prinzmetal angina
Ischemia from coronary artery vasospasms
Transmural ischemia (all layers of myocardium)
Angina vs MI
Angina is reversible (cardiomycotes lack oxygen but are not dead yet)
Stable + unstable angina ECG
ST depression due to subendocardial ischemia
Prinzmetal angina ECG
ST elevation due to transmural ischmeia
ST ELEVATION is caused by
Transmural ischemia
ST DEPRESSION is caused by
Subendocardial ischemia
Normal blood pressure
120/80
GTN spray
Glyceryl trinitrate
Prevents chest pain cause by angina attack
Beta blockers and calcium channel blockers
Anti-arrhythmic
Anti-hypertensive
Aspirin
Anti-thrombotic
Statin
Lowers cholesterol
Ace inhibitors
Anti-hypertensive
Claudication =
Pain in arms/legs while walking/using arms due to too little blood flow
Symptom of peripheral artery disease (arteries that supply legs/arms become narrowed)
Lifestyle changes may help or Statins may help to prevent heart attack/stroke
Angina pectoris =
Stable angina
