Cardio Final Flashcards
Levels of Traumatic Brain Injury (TBI)
mild (concussion), moderate, and severe (coma)
What factors determine intracranial pressure?
blood, parenchymal tissue, and CSF
Dose of Mannitol to decrease ICP
0.25 - 1 g/kg
Explain how mannitol affects ICP
- In cerebral circulation:
- increases osmotic force and causes fluid shift out of tissue compartment into vascular space
How does vascular smooth muscle respond to brief occlusion?
myogenic response
- following, the vessel reamins vasodilated temporarily
- post-ischemic hyperemia
How does vascular smooth muscle respond to prolonged occlusion
maximally dilated and a build-up of CO2 and lactate
- may lead to reperfusion injury
Contraindications for arterial tourniquet
- prosthetic vascular grafts
- patients at risk for DVT
- immobilized patients
- extensive peripheral vascular disease
Compartment Syndrome
edema and blood accumulate within a confined osseofascial space
- comprises circulation and tissues
- more common in tibital and femoral fractures
(3) Risk factors for developing Compartment syndrome
- long bone fractures or trauma
- males under 35 yo
- anticoagulant use
What is mainly secreted in pheochromocytomas?
norepinephrine
Metryosine
(demser)
treatment for pheochromocytoma
- lowers blood pressure by inhibiting catecholamine production
Rapid-onset alpha blockers for Pheochromocytoma
Phentolamine
(5mg as needed)
Which drugs should be avoided in cocaine patients?
- Ketamine
- ephedrine
- succinylcholine
- etomidate
Difference between vascular myocyte and cardiac
vascular myocytes have longer thin filaments and lack troponin
Baroreceptors
sprayed sensory nerve ending found in the adventia of arteries
Baroreceptor location
carotid sinus and aortic arch
(can also be found in the coronary arteries)
afferent nerves from baroreceptors all terminate in the _____
nucleus tractus solitarius
Baroreceptor response
responds to the magnitude (static) and rate of change (dynamic) in pressure
- alters firing rate
Baroreceptor of the Carotid Sinus
origin of internal carotid
- joings Glossopharyngeal nerve (IX) to petrous ganglion
- signal mean pressure and pulse pressure
Baroreceptor of the Aortic arch
located at transverse arch of aorta
- joins vagus nerve (X)
an increase in MAP causes an _____ in baroreceptor firing
increase
A-fibers
large diameter, fast conducting, and myelinated
- low threshold, more sensitive
- active during normal blood pressure
C-fibers
abundant, small diameter, slow conducting, and unmyelinated
- high threshold
- important for high blood pressures
- recruitment of C-fibers occurs around 100 mmHg
Baroreflex
adjusts cardiac output and peripheral vascular tone to stabilize arterial BP
- acute pressure elevation triggers depressor reflex
- hypotension triggers pressor reflex
Depressor Reflex
enchances vagal parasympathetic output and inhibits sympathetic
- bradycardia, decreased contractility, hypotension, and decrease PVR
depressor reflex example
carotid sinus massage
Pressor reflex
increases sympathetic outflow and decreases parasympathetic
- tachycardia, increased contractility, vasoconstriction, and splanchnic venoconstriction
Baroreflex
sensitivity and set point
- sensitivity - “gain”
- slope of response curve
- decreased by age and chronic hypertension
- set point - pressure that reflex tries to maintain
- higher during exercise
(4) Types of Cardiopulmonary Afferents
- myelinated veno-atrial mechanoreceptor
- non-myelinated cardiac mechanoreceptor
- coronary artery baroreceptor
- ventricular chemosensors
Myelinated Veno-Atrial Mechanoreceptors
stretch receptors that measure CVP and atrial filling
- located in great veins and both atria
- tachycardia and diuresis
Bainbridge Reflex
an increase in heart rate due to an increase in CVP
- detected by Veno-Atrial mechanoreceptors
- shifts blood from venous to arterial
Non-myelinated Cardiac Mechanoreceptors
cause bradycardia and vasodilation
- located in atria and left ventricle
- signal over-distension
Coronary Artery Baroreceptors
similar to other baroreceptors but with greater potency
- Bezold-Jarisch Reflex
Bezold-Jarisch Reflex
increased pressure in coronary arteries causes bradycardia and hypotension
- mediated by Coronary Artery Baroreceptors
Ventricular Chemosensors
vagal fibers that mediate ischemic heart pain in the left ventricle
- increases sympathetic activity in response to:
- adenosine, bradykinin, prostaglandin, histamine, thromboxane, lactic acid, K+, and ROS
Cushing’s Reflex
increased ICP causes an increase in peripheral sympathetic activity
Cushing’s Triad
hypertension, reflex bradycardia, and abnormal breathing
Oculocardiac Reflex
pressure on eye or extraocular muscles
- increase parasympathetic tone
- bradycardia
Renin - Angiotensin - Aldosterone
promotes salt and water retention when blood pressure is low
Addison’s Disease
low Aldosterone
- causes hypotension
- chronic adrenal insufficiency
Anti-Diuretic Hormone
(vasopressin)
promotes water retention to restore extracellular volume
- stimulated by low blood volume
Atrial Natriuretic Peptide
promotes salt excretion and diuresis
- reelased in response to atrial distension
- directly affects central blood volume
RAAS response to decreased BP
- increase renin increases:
- angiotensin II
- aldosterone
- Na+ absorption
- fluid absorption
Mechanoreceptors
inhibit cardiac vagal tone
- stimulated by local pressure and muscle contraction
Metaboreceptors
stimulated by substances released during exercise
- more active during isometric exercise due to less blood flow
Somatic Pain response
increase HR and BP
(opposite for visceral pain)
Asphyxia
hypoxemia with hypercapnia
- stimulates increase BP, cerebral perfusion, and oxygen delivery
Clinical Shock
hypotension, hypovolemic, and cardiac shock
- causes rapid breathing and increases peripheral resistance
What regulates alveolar ventilation and BP during asphyxia and clinical shock?
arterial chemoreflex
Nucleus Tractus Solitarus
integrates virtually all cardiovascular afferents and relays them to the hypothalamus, cerebellum, and medulla
Destruction of the nucleus tractus solitarus causes a sustained _____
hypertension
Rostral Ventrolateral Medulla (RVLM)
tonically active vasopressor
- regulated by the CVLM
- primary regulator of the sympathetic nervous system
Paraventricular Nucleus
regulates sympathetic activity
- recieves information from NTS
- project into RVLM and SC to influence sympathetic outflow
- located in hypothalamus
Magnocellular Neurons
secrete oxytocin and vasopressin
- located in PVN of the hypothalamus
Alerting Response
tachycardia, increased CO, vasodilation, and increased BP
- generated by amygdala, hypothalamus, and preiaqueductal grey matter
“playing dead” response
bradycardia and hypotension
- originates in cingulate gyrus of limbic system
Valsalva Maneuver
forced expiration against a closed or narrow glottis that creates high intrathroacic pressure
- ultimately increases stroke volume and pulse pressure while decreasing HR
Oxygen uptake
(equation)
VO2 = Q * (CaO2 - CvO2)
Dynamic exercise
cycles of contraction and relaxation
- increased CO balanced by decreased PVR
Static exercise
isometric contraction
- stimulation of mechanoreceptors
- increase HR, CO, and SVR
endurance is dependent on the maximum rate of ______
O2 transport from lungs to mitochondria
Endurance atheletes
increased CO and SV
eccentric hypertrophy
Eccentric Hypertrophy
increases myocyte length (not width)
- found in endurance atheletes
- increased number of capillaries
- bigger chamber in proportion to increase in wall thickness
Concentric Hypertrophy
increase in wall thickness > chamber size
- found in strength training
- similar to chronic HTN
Diving Response
apenea, bradycardia, and peripheral vasoconstriction
Arterial Oxygen Content
(equation)
CaO2 = (1.31 * Hb * SaO2) + (0.003 * PaO2)
All forms of shock have a decrease in ____ and an increase in _____
decrease in MAP
increase in lactic acid
distributive shock
systemic hypotension, sepsis, anaphylaxis, or neurogenic shock
- decrease
- PAWP, SVR
- increase
- CO, SvO2
Obstructive Shock
PE, cardiac tamponade, VAE, or tension pneumothorax
- decrease
- CO, SvO2
- increase
- PAWP, SVR
Hypovolemic shock
- increase
- SVR
- decrease
- PAWP, CO, and SvO2
Cardiogenic Shock
- increase
- PAWP, SVR
- decrease
- CO, SvO2
_____% of blood loss may produce hypovolemic shock
20-30%
Hemorrhagic Shock
- cardiopulmonary stretch receptors and arterial baroreceptors decline
- chemoreceptor activity increases
- equal MAP, but decreased pulse pressure
Hemorrhagic Shock
(long term responses)
- reduced renal excretion and increased fluid intake
- albumin synthesis
- RBC production
Blood loss ultimately results in increased ____ (4)
HR, contractility, venous tone, and SVR
Framingham Risk Score
determines risk of developing IHD or CVA
- age, gender, cholesterol, smoker, systolic BP, and anti-hypertensive medication
- low risk < 10%
- high risk > 20%
Metabolic Syndrome
group of risk factors that occur together and increase risk for IHD and stroke
- 3 or more:
- waise > 40 or 35
- TG > 150
- HDL < 40 or 50
- fasting glucose > 100
- BP > 130/85
Syndrome X
group of risk factors that indicate predisposition to diabetes
- glucose intolerance, high triglycerides, obesity, and hypertension
Transesophageal echo (TEE)
contraindications
- pharyngeal or esophageal obstruction
- active upper GI bleed
- suspected perforated viscus
- instability of cervical spine
- uncooperative patient
Why should class III patients not recieve a treadmill stress test?
baseline ECG abnormalities
- WPW, paced rhythm, ST depression, or complete LBBB
Treadmill Stress Test
contraindications
- acute MI
- angina
- aortic stenosis
- PE
- aortic dissection
- psychosis
Treadmill stress test is best used in evaluation of a patient with _____
intermediate risk with atypical history or a low risk with typical history
imaging for myocardial ischemia
nuclear imaging or PET
imaging for systolic/diastolic dysfunction
stress echo
imaging for chest pain
history
Pharmocologic stressors in Nuclear Stress Testing
- Dipyridamole (persantine)
- Adenosine
- Regadenoson (lexiscan)
Nuclear stress testing effects _____ receptors
adenosine receptors
A2A - coronary artery vasodilation
Nuclear Stress Test imaging agents
- Thallium
- Tecnhitium
- Sestamibi (cardiolite)
- Tetrofosmin (myoview)
- Teboroxime (cardiotec)
Contraindications for Nuclear Stress Testing
- I-131 therapy within 12 weeks
- Tc-99m studies
- caffeine
- allergies to diphyridamole or aminophylline
- active asthma
What test is the gold standard to find blockages?
cardiac catheterization
coronary angiography or left ventirculography
Cardiac Catheterization contraindications
- coagulopathy
- renal failure
- dye allergy
- active infection
- CHF
- severe hypertension
Acute Coronary Syndrome
blood supply to myocardium is suddenly blocked
- umbrella term including:
- STEMI, non-STEMI, and unstable angina
Fondaparinux
(arixtra)
factor Xa inhibitor
antithrombin
most sensitive and specific cardiac enzyme to test for myocardial damage
Troponin
right-to-left shunt
systemic venous into systemic arterial
left-to-right shunt
pulmonary venous into pulmonary arterial
o reduce right to left shunt flow through a VSD, which should be avoided?
hypoxemia
Atrial Septal Defect
defect in interatrial septum allowing left-to-right shunt
- dyspnea, SVT, right heart failure, and paradoxical embolism
- 2 cm
Patent Foramen Ovale
hole between upper atria
- NOT an atrial septal defect
- venous blood leaks into left atrium
ventricular septal defect
hole between the ventricles
- volume overload to right ventricle
- early pulmonary hypertension
- may develop PVOD
-
most common CHD
- 50% sponatenously resolve
Patent Ductus Arteriosus
hole between pulmonary artery and aorta
- mixed blood goes from aorta into pulmonary artery
- treated with ligation using Pancuronium and ketamine
Coarctation of the Aorta
narrowing of descending thoracic aorta
- often appears with Turner syndrome
- mostly post-ductal
- associated with aortic stenosis, bicuspid valve, and VSD
- increases resistance to left ventricular outflow
Tetralogy of Fallot
combination of four defects:
(VSD, pulmonary stenosis, overriding aora, and RVH)
- most common cyanotic leasion
Treatment of TET spells
- 100% oxygen
- compression of femoral arteries
- morphine
- fluid bolus (15-30 mL/kg)
- NaHCO3 to correct acidosis
- Phenylephrine to increase SVR
what should not be given during TET spells?
beta agonists
(worsens RVOT obstruction)
Hypoplastic Left Heart Syndrome
underdeveloped left heart
- systemic perfusion is dependent on PDA flow
Transposition of Great Arteries
inappropriate orientation of vessels and cardiac chambers
- two circulations in parallel (not series)
- PDA and FO must remain open
Eisenmenger Syndrome
large L-to-R shunt
- develops pulmonary vascular disease and hypertension
classic triad of symptoms with Aortic Stenosis
angina, dyspnea, and syncope
Most common type of aortic stenosis
valvular
Normal arotic valve area
3 - 4 cm2
critical aortic stenosis is AVA < 0.7 cm2
Physical findings of Aortic Stenosis
- pulsus parvus et tardus
- systolic ejection murmur
- paradoxically split S2
paradoxically split S2 causes ____
- severe aortic stenosis
- LBBB
- hypertrophic cardiomyopathy
most common cause of aortic stenosis
age-related calcific degeneration
most common causes of acute mitral regurge
ischemic heart disease, endocarditis, and rupture of chordae tendinae
Primary cause for mitral stenosis
rheumatic heart disease
