Action Potential
After initial spike, the membrane remains depolarized for about 0.2 sec.
What is the plateau?
Reflex initiate by stretch receptors located at specific points in the walls of several large systemic arteries (aortic arch & carotid sinus).
What is the baroreceptor reflex?
•Depress SA node automaticity
•Moderate effect on AV node
•Junctional tachycardia under GA with anticholinergics
What are volatile anesthetics?
End-diastolic volume - end-systolic volume X heart rate
What is cardiac output?
Amount of oxygen that the heart requires to maintain optimal function.
What is Myocardial Oxygen Demand?
Fast sodium channels open when cardiac cell is stimulated and depolarized.
What is Phase O (Depolarization)?
Signals from the carotid baroreceptors are transmitted through these small nerves to the glossopharyngeal nerve.
What is the Hering's nerve?
•High concentrations depress conduction by binding to fast sodium channels
•Depress SA node
What are local anesthetics?
(SV/EDV) x 100
What is ejection fraction?
Heart rate, contractility, preload, afterload, and basal cardiac metabolism.
What are factors that increase of myocardial consumption?
Closure of the calcium ion channels and increased potassium ion permeability, permitting potassium ions to exit the cells rapidly.
What is Phase 3 (Rapid Repolarization)?
Whenever the arterial pressure falls below a critical level, these receptors become stimulated because of diminished blood flow causes decrease in oxygen and build up of carbon dioxide.
What are chemoreceptors?
Causes bradycardia & hypotension - inhibition of sympathetic ganglia, resulting in parasympathetic predominance.
What is regional anesthesia?
HR X Stroke Volume/BSA
What is cardiac index?
Increases myocardial oxygen supply and decreases myocardial consumption, protecting the heart from ischemia.
What are beta blocking medications?
Interval of time during which a normal cardiac impulse cannot re-excite an already excited area of the cardiac muscle.
What is the refractory period?
Activation of these receptors cause reduction in renal sympathetic nerve activity, decreased tubular reabsorption, and dilation of afferent arterioles in the kidneys.
What is the Atrial Volume Reflex?
•Depress cardiac conduction
•Increase AV conduction
•Increase refractory period
•Prolong duration of Purkinji fiber action potential
What is fentanyl & sufentanil?
(MAP – CVP/CO) X 80
What is the formula for Systemic Vascular Resistance?
Most important factor that negatively affects myocardial oxygen consumption.
What is increased heart rate?
Caused by opening of two types of channels: (1) the same voltage activated fast sodium channels and (2) L-type calcium channels.
What is the action potential?
Special type of CNS ischemic response that results from increased pressure of the cerebral spinal fluid around the brain in the cranial vault.
What is the Cushing reaction?
Most cardiotoxic anesthetic and binds inactivated fast sodium channels.
What is bupivacaine?
Coronary blood flow × (sO2 × ceHb × BO2 ) + (PaO2 × 0.03)
What is coronary oxygen delivery?
•Adenosine
•Adenosine phosphate compounds
•Potassium ions
•Hydrogen ions
•Carbon dioxide
•Bradykinin
Prostaglandin
What are the vasodilatory substances released from the myocardium in response to decreased oxygen delivery?