We interrupt your regularly scheduled programming for a brief EKG mini series.
OK so your patient is in third degree heart block this is an unstable rhythm.
no correlation between the QRS and the P wave
p waves may be absent
p waves may be buried in ST
wide or narrow QRS
RR interval is not a multiple of the PP interval
Differential is primary vs secondary heart block
primary heart block--> supportive care till pacemaker placement,
supportive measures--> +/- fluids, pressors chronotropes, transcutaneous pacing, transvenous pacing, circulatory support devices such as intra-aortic balloon/impella/echmo (pacing is rarely effective in the presence of electrolyte abnormality or Medications that block cardiac receptors/channels)
secondary heart block has multiple etiologies
Digoxin acts via hyperkalemia, hypomagnesemia, both contribute to AV nodal block, hypercalcemia contributes to ventricular ectopy and atrial ectopy. can give many ECG changes,
Treatment: Digibind administer number of vials = total mg dose * 1.6 pro tip- round up to the nearest whole number of vials, replete magnesium sulfate, repleat calcium gluconate, Hyperkalemia treatment---> insulin, dextrose, calcium gluconate, Notoriously Refractory to pacing
Beta blocker: treatment high dose insulin therapy, load amp of dextrose 50%, 1 unit/kg IV bolus short acting insulin, dextrose drip, 0.5 - 1 units/kg/hour short acting insulin drip, may titrate up to 2 units/kg, carefully watch for hypokalemia,
Calcium Channel blocker: calcium gluconate 10% is a a temporizing measure but often does not sustain BP and HR, may consider calcium drip, High dose insulin as described above.
endocarditis treat underlying infection, supportive measures may need valve replacement
tumors can cause blocks by invading conduction pathways
Pearl Of The Day written by Nate Marsan MD