Cardiovascular Critical Care I
| (4) | Concentration-dependent protein binding includes about 25% bound to albumin and |
|---|
about 50% bound to α1-acid glycoprotein (AAG).
| (5) | As AAG increases and decreases as an acute-phase reactant within the first 12–72 |
|---|
hours after certain stresses (e.g., acute MI, HF exacerbation, trauma), an unsuspected
variation can occur in free lidocaine concentrations. Because of the toxicity profile
and concentration-dependent efficacy, routine concentrations should be monitored in
most patients if lidocaine is to be continued beyond 24 hours (particularly in patients
with advanced age, HF, liver disease, and renal dysfunction).
Total Serum
Concentration (mg/L)
Toxicity
< 1.5–5
Typical therapeutic goal concentration
> 5–8
Increasing risk of light-headedness, confusion, dizziness, tinnitus, twitching,
tremor, blurred or double vision, hypotension, and bradycardia
> 8
High risk of seizures, respiratory depression, hypotension, bradycardia, AV nodal
blockade, decreased cardiac output
AV = atrioventricular.
| (e) | Procainamide |
|---|---|
| (1) | Indicated for the treatment of hemodyanmically stable, sustained, monomorphic |
VT and atrial fibrillation with pre-excitation (Circulation. 2017;138 (13):e272-391;
Circulation. 2024;149(1):e1-156)
| (2) | Compared to amiodarone, procainamide has been shown to be more effective |
|---|
at terminating monomorphic VT with fewer cardiac complications (Eur Heart J
2017;38:1329-35).
| (3) | Procainamide should be avoided in patients with severe HF, acute MI, and end-stage |
|---|
renal disease.
| (4) | Procainamide is a sodium channel blocking antiarrhythmic, so close monitoring |
|---|
because of the QRS complex is necessary during treatment. Procainamide should be
discontinued if the QRS widens by more than 50%.
| (5) | Close monitoring of the QT/QTc is also important because both procainamide and |
|---|
its active metabolite, N-acetyl procanamide, have potassium channel blocking
properties.
| (f) | Digoxin |
|---|---|
| (1) | Digoxin may be considered to slow a rapid ventricular response in patients with ACS |
and AF associated with severe LV dysfunction and HF or hemodynamic instability
| (2) | Use for AF should be done with caution. Two published retrospective trials have |
|---|
shown considerable evidence for increased hospitalization rates and risk of death.
| • | 71% increased risk of death (HR 1.71; 95% CI, 1.52–1.93) and 63% increased risk |
|---|
of hospitalization (HR 1.63, 95% CI, 1.56–1.71) (Circ Arrhythm Electrophysiol
2015;8:49-58)
| • | Digoxin-treated patients had higher mortality rates (95 vs. 67 per 1000 person- |
|---|
years; p<0.001), and use was independently associated with mortality, despite
multivariate adjustment (HR 1.26; 95% CI, 1.23–1.29, p<0.001) (J Am Coll
Cardiol 2014;64:660-8).