Cardiac Flashcards
Dopamine
Dose-dependent beta-agonist, alpha-agonist, and dopaminergic agonist
2-5 mcg/kg/min: dopaminergic stimulation may cause vasodilation of renal, mesenteric, and cerebral arteries
5-10 mcg/kg/min: beta stimulation resulting in increased cardiac output, mild to moderate peripheral vasoconstriction
10-20 mcg/kg/min: profound increase in peripheral vasoconstriction (alpha effects) and myocardial contractility and HR (beta effects)
Indicated: hemodynamically significant hypotension, systolic BP of 70-100 mm Hg with signs of shock
May result in extreme tachycardia leading to severe dysrhythmias
Beta blockers
Block effect of catecholamines on beta-receptors. Decreases HR, BP, contractility, and bronchoconstriction
Avoid use in bronchospastic disease, symptomatic heart failure, and severe abnormalities in cardiac conduction
Lidocaine
Class IB antiarrhythmic drug
Stabilizes the cell membrane by blocking the movement of sodium into cardiac conducting cells; suppresses ventricular dysrhythmias and elevates fibrillation threshold
Used for ventricular fibrillation and ventricular tachycardia
Adult dosing: 1-1.5 mg/kg IV every 3-5 min. Repeat doses (0.5-0.75 mg/kg) every 5-10 min for maximum of 3 mg/kg
Pediatric dosing: 1 mg/kg IV
Excessive dosing can cause myocardial and circulatory depression
Extreme toxicity can result in seizures
Amiodarone
Adult dosing:
For VF or pulseless VT: 300 mg IV push; second dose is 150 mg IV push if defibrillation is ineffective after first dose (ACLS algorithm)
Pediatric dosing:
5 mg/kg bolus IV or IO
May cause hypotension and bradycardia
Magnesium Sulfate
Reduces sinoatrial node impulse formation and prolongs conduction time. Drug of choice for torsades de pointes
Adult: 1-2 g of a 50% solution (cardiac arrest)
Torsades de pointes: 1-2 g in diluted 100 ml D5W
Pediatric: 20-50 mg IV or IO, max 2 g over 10-20 min
Causes hypotension
Caution with renal failure
Adenosine
Depresses AV and sinus node activity
First line treatment for narrow-complex SVT
Adult: first dose is 6 mg IV. Second dose is 12 mg IV
Pediatric: 0.1 mg/kg IV (max first dose 6 mg). May double and repeat dose once (max second dose 12 mg)
Short half-life may result in recurrent SVT
Atropine
Initial treatment for symptomatic bradycardia
Adult dose: 0.5 to 1 mg IV every 3-5 min
Pediatric dose: 0.02 mg/kg (minimum single dose is 0.1 mg); may repeat once
Can cause tachycardia resulting in ischemia or infarction
Sodium nitroprusside
Potent, rapid-acting arteriolar and venous vasodilator resulting in a decrease in right and left ventricular filling (preload) and peripheral arterial resistance (afterload)
Dose: 0.15 mcg/kg/min infusion
Used in hypertensive crisis, emergency treatment of heart failure, pulmonary edema
Requires arterial line monitoring
Can cause profound hypotension
Metabolized to thiocyanate (cyanide toxicity)
Keep infusion protected from light
Epinephrine
Alpha and beta activity. Increased SVR, BP, automaticity, HR, coronary and cerebral blood flow, myocardial contractility, and myocardial oxygen consumption
Drug of choice in asystole (ACLS)
Adult dosing: 1 mg every 3-5 min
Pediatric: 0.1 mg/kg every 3-5 min
Norepinephrine (Levophed)
Hemodynamically significant hypotension that does not respond to epi or dobutamine
IV infusion: 2 mcg/min and titrate to effect
Strict BP monitoring requires use of an A line
Increases myocardial oxygen needs
May precipitate dysrhythmias
Ischemic necrosis if extravasation occurs, cannot be infused through peripheral line
Dobutamine
Potent beta agonist: increased cardiac output and heart rate
Dosing: 2-20 mcg/kg/min, titrate to effect
May cause tachycardia and dysrhythmias
Mitral Stenosis
Most common form of valve disorder
Etiology: rheumatic fever
S/S: dyspnea, fatigue, palpitations, cough, hemoptysis, chest pain, and embolic events
Diagnostic: atrial fibrillation, diastolic murmur (low pitched, rumbling, heard at apex)
Increased left atrial pressure and volume, decreased cardiac output with increased PAP and PCWP
Preload management to maintain CO and prevent pulmonary edema
Requires CPB and stenotomy
Affects mostly women in their 30s with exertional intolerance
Mitral Regurgitation
Etiology: valve prolapse with CAD, heart failure with dilated LV, bacterial endocarditis, rheumatic heart disease
S/S: atrial fibrillation, pansystolic murmur (high pitched blowing sound best heard at PMI), CXR shows LA and LV enlargement
Back flow results in increased LA volume and LV volume, increased PAP and PCWP
Surgery: vavuloplasty to replace valve
Requires CPB and sternotomy
Medical management: sodium restriction, diuretics, anticoagulants
Aortic Stenosis
Occurs in men 3 times more often
Usually congenital if less than 30 years old
Due to rheumatic fever for those age 30-70
Calcifications in those greater than 70 years old
Initially asymptomatic, fatigue, exertional dyspnea, and syncope caused by sudden drop in SVR. Harsh high pitched systolic crescendo, heard best at right sternal border, 2nd ICS
ECG with LVH and LBBB
CXR with LV enlargement and dilation of the aorta distal to the stenosis
Increased afterload leads to LVH
Pulmonary HTN in the left-sided HF
Requires CPB and valve prosthesis selection
Lethal if not treated
Prophylactic antibiotics are given for high-risk patients prior to dental or other surgical procedures
Do not administer nitrates with this condition
Aortic Insufficiency
Etiology: disease in aortic root from rheumatic heart disease or endocarditis
May be asymptomatic if LV function is normal or may present as left-sided HF with chest pain
High pitched, blowing crescendo diastolic murmur best heard at the 2nd right ICS while patient is sitting
CXR: dilation of LV with elongation of apex, if acute will show pulmonary edema
LV volume overload, increased LVEDP projects backward to increase LA, PAP, and RAP
Surgical valve replacement if symptomatic
All mechanical valves carry a 2-5% thrombo-embolic event incidence
Antibiotic prophylaxis
