Cardiovascular diseases Flashcards
How do you calculate mean arterial blood pressure?
CO* Peripheral resistance
What are 2 causes of increased blood pressure?
- Increased CO (HR X SV)
- Increased peripheral resistance (reduced vessel diameter and increased viscosity)
What is peripheral resistance?
Opposition to flow that blood encounters in vessels away from the heart
What are 2 variables that effect resistance?
- Blood viscosity
- Vessel radius (most powerful)
What elevates blood viscosity?
-RBC count and albumin concentration
What are the two types of baroreceptors?
Arterial (HP) baroreceptors
-located in carotid sinus + aortic arch (fast response)
Low pressure baroreceptors
-walls of major veins + right atrium (slower response)
What do LP baroreceptors do?
- Detect a blood volume decrease
- Cause afferent signals to be sent to hypothalamus
- ADH is released (water reabsorbed)
What does the stretching of atrial receptors (volume increase) do?
Increases secretion of atrial natriuretic peptide (ANP) which promotes increased water and sodium excretion via urine
What does the bainbridge reflex do?
Cause an increase in the heart rate (decreases pressure in S + I venae cavae)
How do the kidneys respond to low pressure baroreceptors
-Secreting excess salt and water via urination
What happens if the GFR falls
- Macula relaxes
- Macula densa stimulates JG cells
- Blood flow increases
- Release of renin from juxtaglomerular cells
What happens if the GFR rises
- More NaCl is reabsorbed
- Reduced paracrine stimulation of JG cells
- JG contract (reduce GFR)
- Mesangial cells contract
What happens when the pressure is rising during systole + decreasing during diastole?
Frequency of afferent impulses increases
Where is the cardiovascular centre located?
In the medulla of the brainstem
What are the 2 components of the cardiovascular centre and what do they do?
- Cardiostimulatory: make the heart beat faster and stronger
- Cardioinhibitory: slow the heart down
What is the vasomotor center?
Cluster of sympathetic neurons in medulla (oversee changes in blood vessel diameter)
What is primary hypertension?
95% of all hypertension
-Combined systolic + diastolic
What is secondary hypertension?
Usually from kidney disease, adrenocrotical disorders, primary aldosteronism, pheochromocytoma, renal artery stenosis & coarctation of the aorta
What are some risk factors for primary hypertension?
-Obesity, genetics, aging, hyperlipidemia, sleep apnoea, smoking, increased blood viscosity
What causes secondary hypertension?
Systemic disease that raises peripheral resistance
What is malignant hypertension?
Intense spam of arteries e.g cerebral arteries, retinal vessels (swelling of optic nerve)
-Sudden development of extremely high blood pressure
What are modifiable risk factors for hypertension
- Diet
- Obesity
- Smoking
- Oral contraceptives
What are some treatments for hypertension?
Diuretics, ACE inhibitors, Ca channel blockers, beta blockers
What is atherosclerosis?
Progressive disease characterised by thickening and hardening of arteries caused by formation of fibrofatty plaques
What is the difference between stable and unstable plaques?
-Stable do not form clots / emboli + only partially block vessels + have thick fibrous caps (unstable = opposite)
What can initially trigger the plaques (6)?
- Hypertension
- Diabetes
- Turbulent blood flow
- Smoking (nicotine)
- Infection
- High cholesterol + LDL
What is stable angina?
Predictable pattern of intermittent angina during exercise/ excitement (relived by rest)
What is variant / prinzmetal angina?
unpredictable course, frequency + duration of pain at rest
What is silent ischemia?
No pain w/ ischemic event
-High association with mental stress
What is unstable angina?
Myocardial ischemia ranging between stable angina to myocardial infarction
What are the 5 common diagnostic techniques?
- Electrocardiogram
- Exercise stress test
- Coronary angiogram
- Holter monitor
- Serum markers
What medication can be used to control blood pressure, heart rate, contractility & left ventricular volume (7)?
- Nitrates (vasodilator)
- Beta blocker (reduce sympathetic tone)
- Angiotensin converting enzyme inhibitors (ACEI) (prevent formation of angiotensin II)
- Calcium channel blockers (reduce contractile force of heart)
- Angiotensin II receptor antagonists (reduce effects of angiotensin II)
- Statins (lipid lowering agents)
- Antiplatelet agents (asprin, sulfinpyrazone, dipyridamole)
What are two surgical treatments for heart conditions?
- Stent insertion
- By-pass graft
What is heart failure?
Inability of the heart to pump blood at a sufficient rate to meet the metabolic demands of the body
What is the difference between left and right heart failure?
- Left = congestive heart failure (cant pump oxygenated blood into A circulation) e.g. pulmonary edema
- Right = inability of heart to pump blood through P circulation e.g. systemic oedema
What are some events that can weaken the heart (leading to failure?)
- Coronary artery disease
- Heart attack
- High blood pressure
- Infections
- Heart valve abnormalities
- Heart muscle diseases
- Heart inflammation
What is the early phase of remodelling characterised by?
Thinning and elongation of the fibrous scar within the infarcted zone
How does the heart respond to stress
- Concentric hypertrophy (Increased LV wall thickness)
- Eccentric hypertrophy
- Efficiency of muscle is reduced leading to reduced cardiac output
What does concentric hypertrophy from pressure overload lead to?
Wall thickening
What does eccentric hypertrophy from volume overload lead to?
Chamber enlargement
What is right heart failure?
- Result of left heart failure (sometimes in result of lung disease)
- Damming back of blood occurs leading to accumulation in systemic circulation
- Peripheral edema
- Enlarged liver
What are causes of left heart failure?
- Myocardial infarction,
- Cardiomyopathies
- Valvular defects
What are the 4 classes of heart failure?
- disease but no limitation in activity
- disease w/ slight limitations (normal activity = fatigue, dyspnea, palpitations, angina)
- disease w/ marked limitations of physical activity
- disease w/ inability to carry on physical activity
- disease but no limitation in activity
What is atrial fibrillation?
Irregular, chaotic beating of the UPPER chambers of the heart
Where does the electrical activity start during an atrial flutter?
-Large ‘re-entrant’ circuit
What are treatments for atrial fibrillation + flutter?
- Medicine to reduce stroke
- Medicine to control fibrillation
- Cardioversion (electric)
- Catheter ablation (uses energy to remove small areas of heart tissue)
- Pacemaker
