Electrophysiology & Vasoactive Agents Quiz Flashcards
What is a cation?
Positively charged Ions that have lost electrons
What is an anions?
Negatively charged ions that have gained electrons
H+ is what Ion?
Hydrogen
Na+ is what Ion?
Sodium
K+ is what Ion?
Potassium
Ca++ is what Ion?
Calcium
Cl- is what Ion?
Chlorine
PO₄³⁻ is what Ion?
Phosphate
What is an Ion?
Any atom or molecule that has a charge
What are Cardiac Muscle Cells called?
Myocytes
What is a positively charge particles located in nucleus?
Protons
What is are neutral particles that are located in the nucleus called?
Neutrons
What are negatively charged particles orbiting the nucleus called?
Electrons
How many particles are atoms composed of?
3 particles
What are the 3 particles that make up an atom?
Protons, Neutrons, and electrons
What is an ionic bond?
When cations and anions bond together they create a
The division of ionic bonds causes the formation of?
Electrolytes
What are the two cardiac cells called?
Myocytes and Pacemaker (nodal) cells
What are Nodal Cells?
They are pacemaker cells
How many phases of the cardiac cycle are there?
There are 5 phases.
What phase is the resting phase of the cardiac cycle?
Phase 4
What phase is the depolarization phase of the cardiac cycle?
Phase 0
What phase of the cardiac cycle is the repolarization (notch waveform)?
Phase 1
What phase of the cardiac cycle is the Plateau Phase?
Phase 2
What phase of the cardiac cycle is the repolarization (complete) phase?
Phase 3
What ion channels open in phase 0 of the cardiac cycle?
Sodium Channels open allowing sodium in.
What Ion Channels close and open in Phase 1 of the cardiac cycle?
Sodium Channels close and Potassium Channels open allowing potassium out of the cell.
What Ion Channels open in phase 2 of the cardiac cycle?
Potassium channels are still open allowing potassium out, but calcium channels open to allow calcium into the cell.
What ion channels open and close during phase 3 of the cardiac cycle?
Potassium channels are still open and calcium channels close.
What channels close during phase 4 of the cardiac cycle?
All channels are closed allowing rest
What do cardiac pacemaker cells make up and are responsible for?
They make up the conductive network and are responsible for the propagation of electrochemical signaling
What do cardiac Myocytes make up and responsible for?
Make up the heart muscle and are responsible for the contraction and movement of blood
What is a concentration gradient?
A variance between the number of ions on either side of the cell membrane
What creates an electrical form of potential energy?
The difference in ion concentrations in and out of the cell
What is Unique to the heart, long thin cells capable of shortening, composted of smaller fibrils, large number of mitochondria for increased ATP production and resistant to fatigue?
Cardiac Myocytes
What is able to generate impulses spontaneously, unique to the heart, transmits impulses through the heart?
Pacemaker cells
What phase of the cardiac cycle is at -90mv?
Phase 4. The resting phase
What are the Phases of the pacemaker cycle?
Phases 4, 0, and 3
What is phase 4 of the pacemaker cycle called?
Phase 4 resting phase
What is the depolarization phase of the pacemaker cycle called?
Phase 0
What is the repolarization phase of the pacemaker cycle called?
Phase 3
At what mv is depolarization triggered in the pacemaker cycle?
-40mv
What mv is the resting phase of the pacemaker cycle?
-60mv
What ion influx causes depolarization of the pacemaker cycle?
Ca++
What Ion channels open to normalize the concentration gradient during repolarization of the pacemaker cycle?
K+
The pacemaker cycle occurs at the rate of what in the SA nodal cells, AV nodal cells, and Purkinje system?
SA: 60-100
AV: 40-60
Purkinje: <40
What is our pro-dominant extracellular ion?
Na+ (sodium)
What is the pro-dominant intracellular ion?
K+ (Potassium)
What ion channels do Cardizem effect?
Calcium Channels
What Ion channels does Amiodarone effect?
Potassium Channels
What Ion channels does lidocaine effect?
Sodium Channels
Nodal cells are leaky to what Ion?
Calcium
Beta 1 agonists increase the permeability of what ion?
Calcium
Unstable myocardium sign is?
A wide QRS complex
What are the 3 stages to stabilize Hyperkalemia?
Stabilize myocardium, shift intracellular, and elimination of K+
How doe you stabilize the myocardium in hyperkalemia?
Treat with CaCl (Calcium Chloride) and/or NaHCO₃ (sodium bicarbonate)
How do you shift the potassium intracellularly in Hyperkalemia?
Treat with insulin 0.1 units/kg
How do you eliminate K+ in Hyperkalemia?
Cause the patient to urinate or have bowel movements to help get rid of it or dialysis. For example lasix to urinate and Kayexalate.
Sodium Channel Blocker toxicity treatment?
Sodium Bicarbonate, possibly seizure control, and airway management
Hypokalemia and Hyperkalemia can lead to torsades de pointes because?
Of the widening QRS interval.
A QTC >500 is more likely to?
Lead to torsades de pointes
What drug has the least effect on QTC interval?
Lidocaine
What drug has the most QTC prolongation effects?
Amiodarone
Sympathetic stimulation releases?
Adrenergic neurotransmitters (Epi and NorEpi)
What drug stimulates Beta 1 receptors?
Epinephrine
Stimulation of the Beta 1 receptors releases what?
Intracellular cAMP
cAMP is what?
Cyclic adenosine monophosphate
Increased cAMP levels reduce what and promote what?
Reduce time for action potential to occur.
Promotes a more complete contraction of the Myocyte.
Parasympathetic stimulation releases what?
Antagonistic neurotransmitters (Acetylcholine)
Acetylcholine binds to what? Which causes what?
Muscanaric receptors and causes decreased cAMP levels intracellular
Decreased cAMP levels intracellular causes what?
A reduce in heart rate, force of contraction, and conduction velocity
Stimulation of the vagus nerve increases?
Parasympathetic activity.
Sodium Channel Blockade effects what phase of the cardiac cycle?
Phase 0, Depolarization phase
Signs and symptoms of a Na+ channel blockade?
Depolarization is prolonged, QRS widened, QT prolonged, heart rate reduced, reduced membrane excitability, and refractory period is prolonged.
Higher extracellular Na+ levels allow?
The body to tolerate a greater fluctuation in serum levels
What can cause a sodium channel blockade?
TCA overdose, Cocaine toxicity, Diphenhydramine overdose.
Minor variations of what Ion can cause significant ECG changes?
K+
Ion that has a very prominent role in the cardiac cycle?
K+
What ECG sign is the most common with HyperK?
Peaked T waves
Sign wave is a sign of?
Impending death due to potassium increase outside the cell
First treatment rendered if a sign wave is notable on ECG?
Treat with Calcium Chloride or Sodium Bicarbonate
HyperK treatments?
Calcium Chloride, Sodium Bicarbonate, Insulin infusion, dextrose infusion, albuterol, diuretics, hemodialysis
What is Hypokalemia commonly caused by?
Diuretics, diarrhea, dialysis
Signs of hypokalemia?
A delay in repolarization, prolonged QT segments, ST segment depression, T wave inversion with the “U” wave, PR prolongation
Treatment for Hypokalemia?
Administration of LR, comfort measures for pain and muscle spasms. Sometimes IV potassium.
What is primarily caused by hyperparathyroidism?
Hypercalcemia
Hypercalcemia effects was phase of the cardiac cycle? What does it do to the phase?
Phase 2 (plateau phase.) shortens which means a shortened QT segment.
Calcium plays a crucial role in what?
Both myocardial contraction and signal conduction
Common target for pharmaceutical intervention do dysrhythmias and management of cardiac output?
Calcium channels
The primary cation for initiation of impulses in the SA node?
Calcium
What functions very similar to calcium?
Magnesium
Primarily caused by hypoparathyroidism?
Hypocalcemia
What phase is effected by hypocalcemia?
Phase 2 (Plateau phase) prolongs and causes prolonged QT segment
Hypocalcemia increases?
Contraction and excitability of non-cardiac muscle cells
Treatment for Torsades De Pointes?
Mag Sulfate 1-2 grams IVP, cardioversion
Calcium channel blockade effects what phase?
Phase 2 (Plateau phase) causes an extension of the action potential
What are the 2 major kinds of calcium channel blockers?
dihydropyrodines, non-dihydropyrodines
Signs and symptoms of an overdose on a Non-dihydropyridine calcium channel blockers?
Hypotension, Bradydysrhythmias (Esp AV blockers), Ventricular Dysrhythmias, Junctional Dysrhythmias, Asystole
Signs and symptoms of a Dihydropyridine calcium channel blocker?
Tachycardia and vasodilatory shock.
What will calcium channel blocker toxicity typically result in?
Hyperglycemia
Beta blocker toxicity signs and symptoms?
Hypotension, bradydysrhythmias (es. AV blocks), Junctional Dysrhythmias, and ventricular Dysrhythmias
Beta blockers bind to what and and block what?
Beta receptor sites and block stimulation from catecholamines
Cardioselective beta blocking agents target what beta receptor?
Beta 1
Beta blockers do what?
Reduce SA node firing rate. Conduction through AV node is slowed and arterial repolarization is prolonged
ECG findings of beta blocker overdose?
P wave activity is reduced, PR segment is prolonged, QRS width depend on origin of impulse, and QT segment is prolonged
Treatment of a beta blocker overdose?
Glucagon 2-5mg IVP (Recent evidence shows to be ineffective) High dose insulin therapy, Pacing can be attempted but reduced success rate.
4 major classes of Vasoactive drugs?
Inopressor, Inodilator, Vasopressor, Vasodilator
Right ventricle is a
Low pressure circuit
Left ventricle is a
High pressure circuit
Central venous pressure (think preload)
Right side
Diastolic pressure (Think afterload)
Left side
Alpha 1 receptors target?
Venal and arterial system
Beta 1 receptors target?
Ventricles
Beta 2 receptors target?
Bronchioles
Ino means?
Targets heart in some form
Inopressors do what?
Increases contraction of heart and increases vasoconstriction
What drugs are inopressors?
NorEpi, Epi, Dopamine
Norepinephrine’s common name?
Levophed
Does for norepi?
2-20 mcg/min
NorEpi is
The frontline agent for most shock states especially sepsis
NorEpi stimulates what receptors and how?
Alpha 1 agonist by vasoconstriction, has mild beta effects but minimal on heart rate. Lower doses can cause venoconstriction which augments preload.
How do you mix levophed and what is the concentration?
4mg in a 250mL D5W. concentration is 16 mcg/mL
Epinephrine is the?
Frontline agent in anaphylaxis
Epi effects what receptors and how?
Alpha 1 and Beta 1 and 2 agonism. Effects vasoconstriction, inotropy, and heart rate. Can be proarrhythmic due to the beta agonism
What is the dose to Epi?
2-20 mcg/min
How do you mix Epi and what is the concentration?
1mg of 1:1 Epi in 100mL of D5W. Concentration is 10 mcg/mL
Dopamines concentration?
800mg/250mL of D5W
Dose to Dopamine?
2-20 mcg/kg/min
Why is dopamine not primarily used anymore?
It’s difficult to use effectively as its effects change as you increase dosage
What receptors does dopamine effect?
Alpha 1, beta 1, beta 2 agonism.
What’s the dosage of dopamine to effect Alpha 1 receptors?
Up to 10 mcg/kg/min
What’s the dosage of Dopamine to get Beta receptor effects?
10 mcg/kg/min and higher
What drugs are vasopressors?
Phenylephrine (Neosynephrine) and Vasopressin (ADH)
What does phenylephrine effect and cause?
Strong alpha 1 agonism and causes potent vasoconstriction without effect on the heart
What dos vasopressin effect and cause?
Targets V receptors and causes potent vasoconstriction. Also stimulates the retention of solute-free water.
What drugs are inodilators?
Dobutamine and Milrinone (primacor)
Dosage of dobutamine?
2-10 mcg/kg/min
Milrinone dosage?
0.375-0.75 mcg/kg/min
Dobutamine effects what receptor and causes what?
Very strong beta 1 agonism, increases heart rate, force of contraction and causes vasodilation.
When is dobutamine indicated?
Heart failure and cardiogenic shock
What does Milrinone do and effect?
Phosphodiasterase inhibitor and increases force of contraction and vasodilation
When is Milrinone indicated?
Indicated in heart failure and cariogenic shock (Mainly seen with pediatrics)
What drugs are vasodilators?
Nitroglycerin, Nicardipine, and Nitroprusside
What does Nitro do?
Strong venodilator and mild arterial dilation. Effects arteries with increased dosages.
What’s the dosage for Nitro?
5-400 mcg/min
What does nicardipine effect and do?
Arterial selective calcium channel blocker. Strong arterial dilator
Dosage of Nicardipine?
5-15 mg/hr must titrate cautiously
Common name for nicardipine?
Cardene
Common name for nitropprusside?
Nitropress
What does nitroprusside do?
Very potent arterial dilator
What does nitroprusside breakdown to and what to watch for?
Breaks down to nitric oxide. Watch for cyanide toxicity
With this medication a arterial line placed is highly recommended
Nitropress
How many Anti arrhythmic drug classes are there?
4
What is class 1 effect? antiarrythmics
Na+ (Lidocaine, Procainmide)
What does class 2 effect? Antiarrythmics
Beta blockers (Metoporol, Esmolol, Labetalol)
What does class 3 effect? Antiarrythmics
K+ (Amiodarone)
What does class 4 effect? Antiarrythmics
Ca++ (Cardizem, verapamil)
Hyperkalemia is seen in patients with?
Rhabdomyolysis, Burns, Profound acidosis, Crush patients for compartment syndrome.
Nitro dose to cause venodilation?
5-50 mcg/min
Nitro to cause arterial dilation?
50-100 mcg/min starting range.
