The hypotensive and bradycardic patient
Notes from Ben Sandefur Grand Rounds "The hypotensive and bradycardic patient"
By Damian Baalmann, M.D.
Broad Differential for Hypotensive + Bradycardic Patient
- Toxic
- CCB
- Beta Blocker
- Cardiac Glycodisde (Digoxin)
- Alpha-2 Agonist (Clonidine)
- Organophosphate
- Cardiac
- Cardiac Conduction Disease
- Infarction
- Primary Conduction Disease
- Pacemaker Failure
- Infectious: Lyme Carditis/ Chaga’s Disease
- Cardiac Conduction Disease
- Electrolyte
- Hyperkalemia
- Endocrine
- Hypoadrenalism
- Hypothyroidism
- Environmental
- Hypothermia
- Gastrointestinal
- Massive GI Bleed (vaso-vagal response)
- Neurogenic
- Neurogenic Shock
- Remember that often the presentation is multifactorial. Additionally, bradycardia + hypotension is often the final common pathway for dying patient, regardless of etiology.
Calcium Channel Blockers
- Classic Non-Dihyhdropyridine CCB overdose: Hypotensive, Bradycardic, and Hyperglycemic
Beta-Blockers
- Pharmacology: G-Protein Linked Receptor→Adenylyl cyclase→cAMP→PKA
- Beta-Blocker Overdose: Hypotensive, Bradycardic, Hypo- or Normoglycemic
- CNS effects with propranolol (b/c it crosses the BBB)
Therapeutic Options for CCB or Beta-Blocker Toxic Patient
- Give Calcium!
- Calcium Gluconate: PIV, dose: 3-6g
- Calcium Chloride: Central access, dose: 1-2g
- Glucagon
- Activates G-protein and bypasses B-blocker
- Amrinone
- Increases cAMP in the cell
- Vasopressors
- Works on Beta receptor
- Insulin
- Overcomes hypoglycemia of CCB
- Glucose entry in the Myocytes →increase ionotropy
- Bolus 1U/kg, infusion 1-10U/kg/hr, D10 @100mL/hr, replete K+, avoid vasopressors
- Intralipid Therapy
- 1.5 mL/kg of 20% solution of 2-3min; 0.25-0.5 mL/kg/min drip for 30-60 min
- Data not quite as robust as hyperinsulinemia therapy
- Also think of Transvenous Pacemaker, Intra-aortic balloon pump, ECMO, Cardioplumonary Bypass
Summary
- Think broadly with differential of hypotension and bradycardia
- Animal data strongly supports using insulin for increasing survival in CCB and beta-blocker; vasopressors ↑SVR and may be counterproductive
- Glucagon, Vasopressors, and Amrinone all display tachyphylaxis because they rely on cAMP pathway which eventually is depleted
- Consult Poison Control Center Early: 1-800-222-1222
- High-dose insulin therapy has emerged as an effective therapy for CCB and beta-blocker toxicity
- Lipid Emulsion Therapy may be helpful in cardiotoxicity or cardiac arrest from lipophilic cardiotoxic medications, but the data is not as compelling