PowerPoint Chapter 14 Flashcards
Some drugs can cause ____ or ____ imbalances?
Some drugs can cause arrhythmias or electrolyte imbalances
What are four things medications can cause?
Some drugs can cause arrhythmias or electrolyte imbalances
-Indirect or direct arrhythmias
-Electrolyte imbalances
-QT prolongation
-Progression to Torsades de pointes
What are two common medications used for the heart?
Medications that are common
Digoxin
Anti-arrhythmics
What are three types of anti-arrhythmics?
Calcium Channel Blocker
(Decrease cardiac contraction of myocytes and decrease amplitude and rate of SA/AV node.)
Beta Blockers
(Act on Beta Receptors decreasing HR)
Potassium Channel Blockers
(Influences Repolarization phase of contraction)
What are three different electrolyte disturbances?
Electrolyte disturbances
-Calcium, Potassium, & Magnesium
Digoxin is a ____ ____?
Cardiac glycoside (lower HR)
What does digoxin do/used for?
-Heart Failure and supraventricular arrhythmias
-Increases Vagal tone and decreases SNS –> decreased conduction velocity and increased refractory period
-(Decreases amount of Atrial Depolarization that reach the ventricles)
How does digoxin appear on an ECG (4)?
ECG Changes
-Shortened QT Interval
-Down sloping ST seg
-T wave inversion/flattening
-PR interval prolongation
Symptoms (4) of digoxin toxicity include?
Symptoms include: Vision Changes, Nausea or Anorexia, Dizziness, Difficulty reading.
Patients with ____ ____ ____ will struggle with Digoxin?
Patients with poor kidney function will struggle with Digoxin
Digoxin toxity can cause the appearance of___________________________?
Appearance of Arrhythmias, Conduction blocks or both
Bradyarrhythmia + Heart block
Atrial and Ventricular Tachyarrhythmias
What is a classic sign on ECG of digoxin?
“Scooping ST segment”
What do calcium channel blockers do (4)?
Inhibit calcium moving into myocardial cells
Causing vasodilation or smooth muscle relaxation
Decrease contractility of heart (neg inotropic effect)
Decrease HR (Neg chronotropic effect)
Depress conduction velocity with in heart esp. SA and AV node tissue
(Neg dromotropic effect)
Calcium channel blockers ECG effects?
R-R interval increases
PR Intervals increase
What are drug induced arrhythmias from calcium channel blockers?
Drug induced arrhythmias
Sinus bradycardia
-1deg heart block
What do beta blocker do?
Antagonists at sympathomimetic neurotransmitter receptors
Work on Cardiac Output and SA/AV node conduction
Reduce HR and myocyte muscle contraction
Beta blocker ECG effects?
PR interval increase
Beta blocker drug induced arrhythmias?
Sinus Bradycardia
1st deg heart block
What are two things that prolong the QT interval?
Result of drug therapy, Electrolyte disturbances
What does prolonging the QR interval increase the risk of?
Risk of Torsades de pointes
What are the two avenues in which the QT interval is prolonged?
Prolonged depol
Reduced repol
Acquired ____ prolongation is an imperfect surrogate for ____ ____ ____ risk?
Acquired QT prolongation is an imperfect surrogate for TdP risk
Non-antiarrhythmics are ____ ____ in leading to TdP?
Non-antiarrhythmics are less frequent in leading to TdP
What non-antiarrhythmics (3) lead to Torsades de pointes?
Typical antipsychotics – are associated with TdP
Atypical antipsychotics – varying degree
Tricyclic antidepressants
Normal range for potassium?
Potassium (K)
3.5-5.5 mmol/L
Normal range for calcium?
Calcium (Ca2+)
8.5-10.5 mg/dL
Normal range for magnesium?
Magnesium (Mg)
1.7-2.2 mg/dL
Normal range for sodium?
Sodium (Na)
135-145 mEq/L
What electrolyte is least likely to affect QRS amplitude?
Hyponatremia (sodiaum/Na)
(No ECG effects)
Rarely decrease in QRS amplitude
What does hyperkalemia cause (2)?
Hyperkalemia (high potassium)
Decrease in Myocardial excitability
Risk for Torsade’s de Points(TdP)
(40% of TdP cases have low serum potassium and magnesium.)
__% of TdP cases have low serum ____ and ____?
40% of TdP cases have low serum potassium and magnesium
What does hypokalemia cause and what does it increase risk for?
Hypokalemia (low potassium)
Myocardial hyperexcitability
Increased risk for Atrial Fib or TdP
What are ECG signs of hypokalemia?
ECG Signs
ST depression, flattened T wave, prominent U wave in precordial leads
QT interval prolongation (and increased risk of TdP)
What is hypercalcemia defined as?
Calcium serum > 10.8mg/dL
What does hypercalcemia cause?
Increased myocardial contractility and irritability
ECG signs of hypercalcemia (2+1+2)?
Short QT interval, ST seg elevation
Other signs
-T wave wide/flat,
-Conduction blocks,
-Ventricular abnormalities
What is hypocalcemia defined as?
Calcium serum < 8.5 mg/dL
What does hypocalcemia cause?
Decreased myocardial contraction
Hypocalcemia ECG signs?
Long QT interval (by lengthening ST seg
increased risk for TdP)
What is hypermagnesiemia classified as?
Serum magnesium > 2.5 mEq/L.
What ECG changes appear at what levels of hypermagnesemia?
ECG changes progress with magnesium overload
> 4 mEq/L:
-Prolongation of PR interval,
-Increase in QRS duration
-Increase in QT interval.
> 10 mEq/L: Complete heart block and asystole possible.
What is hypomagnesimia classified as?
Serum magnesium < 1.5 mEq/L
What is hypomagnesimia associated with?
Often with hypocalcemia and/or hypokalemia (similar ECG changes).
What ECG changes occur with hypomagnesemia?
Prolonged PR + QT intervals
ST depression
Hypomagnesimia is associated with ____ ____, particularly during ____ ____ or ____ ____, particularly in patients taking class IA or class III ____ drugs.
Hypomagnesimia is associated with ventricular arrhythmias, particularly during myocardial ischemia or cardiopulmonary bypass, particularly in patients taking class IA or class III antiarrhythmic drugs.
