3.1 Chronic Cardiovascular Disorders Flashcards
Blood Pressure
- Blood pressure is Cardiac Output multiplied by Peripheral Vascular Resistance. (CO x PVR)
- Cardiac output is Heart Rate times Stroke Volume
- Pressure exerted by blood as it flows through vessels
- Systolic is pressure as heart beats
- Diastolic is pressure as heart relaxes
Pulse Pressure
- Difference between systolic and diastole pressure
- Mean Arterial Pressure (MAP) - Average Blood Pressure
2xDiastole + Systolic divided by 3 - MAP is used when manipulating medications and drips that lower or increase someone’s blood pressure.
What Influences Blood Pressure
- Contraction of left ventricle (how it is working)
- Cardiac output influences systolic BP
- PVR influences diastole BP
- Stroke Volume
- Elasticity of Arterial Walls
- Thickness of volume and blood
- Age
What Influences Blood Pressure
Cardiac Output
- Heart Rate, Contractility, Conductivity (Cardiac)
- Renin-Angiotensin-Aldosterone System, Natriuretic Peptides - stretch of cardiac muscle (Renal Fluid Volume Control)
PVR
Sympathetic Nervous System
- A-Adrenergic Receptors (Vasoconstriction)
- B-Adrenergic Receptors (Vasodilation)
Neurohormonal
- Vasoconstrictors
Angiotensin, Norepinephrine
Local Blood Pressure Regulation
Vasodilators - Prostaglandins - Nitric Oxide Vasoconstrictors - Endothelin
Blood Pressure Influencers
- Baroreceptors are found on walls of blood vessels like aorta and carotids. They communicate with brain and medulla when vessels are stretched and parasympathetic nervous system will drop blood pressure.
- Baroreceptors communicate when blood pressure rises or when CNS activates fight or flight response or need to increase heart rate.
Sympathetic Nervous System
- Increase heart rate and cardiac contractility
- Kidneys and endocrine system play a part in sodium and fluid regulation which helps control blood pressure
- These are geared towards increasing cardiac output and SVR. Kidneys holding onto fluid and sodium.
Factors influencing blood pressure
- Baroreceptors
- Renal system controlling sodium and fluid volume
- RAAS
Renin - Released when drop in blood pressure
Angiotensin 2 - Vasoconstrictor
Aldosterone - Reabsorbs water/sodium
Holding onto sodium and water increases blood pressure
Epinephrine/Norepinephrine
- Released by adrenal medulla
- Fight or Flight response
- Speeds up heart rate which increases cardiac output
- ## Adrenal cortex releases aldosterone from posterior pituitary increasing water retention and blood pressure
Hypertension
- Affects 50-60 million adults in the US
- Increases risk of MI (heart attack)
- Heart failure
- Stroke and Kidney Disease
- Silent Killer
- 95% of hypertension cases are primary/essential
- No Known Cause
- 5% of cases are considered secondary
- They do have a cause
Risk Factors
Modifiable
- Change sodium intake, decrease weight, obesity, increase activity, stop smoking/alcohol, prevent type 2 diabetes.
Non-Modifiable
- Family history, age, race, type 1 diabetes, decreased nephron count.
Blood Pressure Readings
- Based on average of 2 or more properly measured seated readings on 2 or more office visits
- White Coat Syndrome - Anxious when being seen by a health care provider which elevates BP
BP Readings
Normal - Less than 120 / Less than 80
Elevated - 120-129 / Less than 80
Stage 1 - 130-139 / 80-89
Stage 2 - 140+ / 90+
Crisis - 180+ / 120+
Primary Hypertension - No Source (Genetic)
Secondary - Has a Cause (Pregnancy, Renal Problems, Tumor)
Primary Hypertension
- Persistent increase in SVR
- Can cause enlarged left ventricle (hypertrophy)
- Often isn’t detected until there’s damage to target organ
- Hemorrhagic stroke or brain issue due to hypertension
- ## Could be genetic link, stress, increase in sympathetic nervous system (increase heart rate, increase renin released by kidneys)
Primary Hypertension Pathophysiology
- Altered renin production, aldosterone.
- Insulin resistance, hyperinsulinemia, increases sympathetic nervous system activity
- High insulin impairs nitric oxide mediated vasodilation function
