Pacemakers Review Pt. 1


    Pacemakers Review Pt. 1

    The pursuit of mastery over cardiovascular emergencies demands a rough familiarity with implanted devices which includes why they get implanted in the first place (indications), how they work, how they malfunction, and how they affect the EKG., among other features. Today we’ll we’ll start with the basics of implanted pacemakers including indications, anatomy, and radiography.

    Generally speaking, patients are suitable for pacemaker implantation when they exhibit 1) symptomatic bradycardia or symptomatic chronotropic incompetence (i.e. inability to generate an age appropriate heart rate during exertion) 2) third degree AV block 3) Mobitz Type II second degree AV block 4) carotid sinus mediated recurrent syncope 5) sustained PAUSE-DEPENDENT ventricular tachycardia and 6) severe CHF i.e. with electromechanical ventricular dyssynchrony.

    Complications include infection, upper extremity venous thrombosis, hemothorax, pneumothorax, and pocket hematoma.

    pacemaker anatomy


    An external file that holds a picture, illustration, etc.
Object name is JCIS-4-74-g003.jpg



    A pacemaker consists of a pulse generator usually implanted subcutaneously usually in the left infraclavicular fossa with leads traversing the ipsilateral subclavian vein.  The typical “dual chamber” pacemaker will have one lead tip implanted in the right atrial appendage and a second tip in the right ventricular apex.  The above picture has a third lead traversing the coronary sinus for placement in the left ventricular wall (i.e. biventricular pacing).

    Note the white arrow pointing to the right atrial lead and the black arrowhead pointing to the right ventricular lead. Appropriate positioning of the generator in the left infraclavicular fossa can be compared with prior chest XR.


    That’s it for part 1.  In the next post we’ll cover pacemaker function and how to interpret their unique electrocardiographic morphologies.


    • Welcome! This is the website for the Mount Sinai Emergency Ultrasound Division. It serves as an information resource for residents, fellows, medical students and others seeking information about point-of-care ultrasound. There is a lot ofRead more

    • Bag Mask Ventilation During Intubation

      A few days ago NEJM published the results of an investigation with profound implications for our specialty.  A group of intensivists and anesthesiologists conducted a multicenter, randomized trial conducted in seven ICUs to study theRead more

    • Gastric Emptying for Acute Poisonings

      At the request of department leadership, we will be revisiting methods of gastric decontamination for today’s pearl.  Two methods in particular. Ipecac-induced emesis and gastric lavage are two procedures that we read about in medicalRead more

    • Pacemakers Review pt. 3

      Today we will review complications associated w/ implanted pacemakers that you may encounter in the ED and thus ought to be familiar with. Generally, complications can be divided into two categories: early vs. late EarlyRead more

    • Pacemakers Review Pt. 2

      Cardiac pacing as an intervention can be conceptualized as addressing problems in electrophysiological conduction and/or.  So, for example, if there is a disruption in the electrical continuity between the atrium and the ventricle, a pacerRead more

    • In honor of a rosh review question that I got wrong, lets review Lyme disease!   Lyme disease is caused by the spirochete Boriella burgdorferi, transmitted to humans through tick bites from ixodes ticks. Location:Read more


      Your patient has an SBO and has repeated bilious emesis on the side. The surgery team is in the OR and they ask if you can place the nasogastric tube (NGT). Lets review proper NGTRead more

    • No, that’s not an olive. That’s Pyloric Stenosis!

      Inspired by what appears to have been a very interesting day in the Peds ED, lets review a rare but interesting pediatric entity: PYLORIC STENOSIS Background: MC in Males (5:1) & firstborn children (30%) UsuallyRead more

    • Ouch that monkey bit me!

      At the request of a colleague who recently treated a patient bitten by a monkey, I am going to write about treatment and prophylaxis for animal bites. First, a little BIT (get it?) about monkeyRead more