Cardio A/P Flashcards
preload
amount of ventricular stretch
amount of volume in the ventricle at the end of
diastole
afterload
○ resistance against which the heart must pump to
circulate blood
○ increases cardiac workload
Heart wall layers
■ Pericardium- double walled heart sac
■ myocardium- muscle layer
■ endocardium- inner lining
myocardial contractility
heart rate: increased HR-> increased CO
Blood pressure regulation via
■ RAAS
■ Baroreceptors
difference between RAAS and Baroreceptors Blood pressure
The renin–angiotensin–aldosterone system (RAAS) is a critical regulator of blood volume and systemic vascular resistance on a long-term basis.
The baroreceptor reflex, on the other hand, responds in a short-term manner to decreased blood pressure. Arterial baroreceptors inform your autonomic nervous system of minor or rapid beat-to-beat changes in blood pressure.
What are the renin-angiotensin-aldosterone system (RAAS) steps?
When your blood pressure falls, your kidneys release the enzyme renin into your bloodstream.
Renin splits angiotensinogen, a protein your liver makes and releases, into pieces. One piece is the hormone angiotensin I.
Angiotensin I, which is inactive (doesn’t cause any effects), flows through your bloodstream and is split into pieces by angiotensin-converting enzyme (ACE) in your lungs and kidneys. One of those pieces is angiotensin II, an active hormone.
Angiotensin II causes the muscular walls of small arteries (arterioles) to constrict (narrow), which increases blood pressure. Angiotensin II also triggers your adrenal glands to release aldosterone and your pituitary gland to release antidiuretic hormone (ADH, or vasopressin).
Together, aldosterone and ADH cause your kidneys to retain sodium. Aldosterone also causes your kidneys to release (excrete) potassium through your urine.
The increase in sodium in your bloodstream causes water retention. This increases blood volume and blood pressure, thus completing the renin-angiotensin-aldosterone system.
How is the RAAS related to heart failure?
In particular, the RAAS releases more of the hormone angiotensin II to try to compensate for the lack of blood flow. This excess of angiotensin II subsequently makes heart failure worse. Scientists believe excess angiotensin II contributes to growth in the size of your heart.
How does the baroreceptor reflex work?
When there’s a change in your blood pressure, your artery walls respond accordingly. For example, with increased blood volume, your blood vessel walls stretch. In certain parts of your body, baroreceptors, which are special nerve endings, can “sense” artery wall stretch. This message goes to your brain, which interprets it as adequate blood pressure. In the absence of this stretch, your brain responds accordingly to raise your blood pressure.
If you stand up quickly, your baroreceptors sense a lack of stretching of the artery walls. This message goes to your brain, which interprets it as inadequate blood pressure. Your brain tells your blood vessels to tighten up in order to raise your blood pressure. This is just one way your body can control your blood pressure.
What triggers the baroreceptor reflex?
Any change in your body’s demand for blood can trigger your baroreceptor reflex. For example, your body may need to adjust your blood pressure when you:
Change your body position, such as when you stand.
See or experience something that frightens you.
Switch from walking to running
Common signs or symptoms of conditions associated with dysfunctional baroreceptor reflex
Unstable blood pressure.
Too much or too little blood reaching your organs.
Tachycardia.
Inability to raise heart rate appropriately.
Common treatments for the baroreceptor reflex
Midodrine.
Droxidopa.
Fludrocortisone.
Calculate Mean Arterial Pressure
MAP= SBP +2(DBP) all divided by 3
Define MAP
the average pressure in the circulation, based on length of cardiac
cycle
Define Primary (Essential) Hypertension
constant elevation of systemic arterial BP
Causes/pathophysiology of hypertension (primary)
● SNS hyperactivity
● Overactive RAAS
● Defect in natriuresis
● Insulin resistance
● Inflammation and endothelial dysfunction
Values for Normal BP
<120 and <80
Values for Pre
120-139
Values for stage 1 hypertension
140-
159
BP value that indicates Hypertensive Crisis
Diastolic BP >140 mmHg
Complicated HTN – multiorgan effects
stroke, acute encephalopathy, retinopathy, MI, general atherosclerosis, albuminuria, proteinuria, renal failure
Orthostatic Hypotension – criteria/how to assess
Decrease in systolic BP of at least 20 mmHg or diastolic BP of at
least 10 mmHg within 3 minutes of moving to standing position
■ 1. Have pt lie down for 5 mins
■ 2. Measure BP
■ 3. Have pt stand
■ 4. Repeat BP measurements after standing for 1 and 3 minutes
Varicose veins complications
○ Leads to venous hypertension, blood stasis, and
tissue hypoxia
○ Can lead to venous stasis ulcers which do not heal
because they do not get enough oxygenation
Thrombus:
blood clot attached to vessel wall
Embolus:
detached/moving thrombus
Embolism:
obstruction of a vessel by an embolus
Virchow’s triad:
factors that promote thrombus formation
Risk factors for – Virchow’s triad:
● Stasis of blood flow
○ Bed rest, immobilization
● Endothelial damage
○ Trauma, caustic intravenous medications
● Blood hypercoagulability
○ Inherited hypercoagulability, medications, pregnancy
Homan’s sign
Homan’s Sign (or Homans Sign) is a classic test for DVT (Deep Vein Thrombosis). The test is positive if the patient experiences (severe) calf pain when the ankle is passively dorsiflexed.
difference between true vs. false aneurisms
■ False: extravascular hematoma that communicated with the
intravascular space
■ True: involves all three layers of the arterial wall
Describe Fusiform/saccular aneurisms
Saccular looks like a skin tag on a vessel. ranges from 5-20cm in diameter. Often contains a thrombus.
Fusiform looks like a obese part of the vessel. “circumferential dilation of vessel”. Up to 20cm in diameter. Usually found in BIG arteries like to aorta, abdominal aorta, and iliac (inguinal) arteries
describe pulsatile hematoma
false aneurism that creates hematoma on the outside of the vessel wall. causes ventricular aneurisms and aortic dissections