ECG CH 10 Pacemaker Rhythms and Bundle Branch Block (BBB)

Atrioventricular Sequential pacing (AV Seq)

Mimics the normal CO conduction system. Provides direct stimulation of the atria and ventricles in a sequence pattern. -it allows the atria to contract completely prior to the ventricles to allow an atrial kick which provides extra blood supply needed for normal CO.

Ventricular Pacing

Pacemaker: the spike will be followed by wide QRS

Atrial Pacing

Pacemaker; the spike will be followed by a P wave

Malfunctioning

(Failure to pace) The pacemaker fails to send an electrical impulse to the myocardium. Pacemaker intervals are irregular and impulse is slower than set rate. no pacemaker spike is seen. *Pt will most often experience hypotension, light headedness, and blackout period due to bradycardia condition.

Pacemaker Rhythm

(artificial pacemakers) mimics the normal pacemaker of the heart as a electric generator and deliver small amount current in predetermined interval to the myocardium, causing cells to depolarize. Can pace atria, ventricles, or both. Its individually set for the desired heart rate and electrical current.

Loss of Capture

(failure to depolarize) The pacing activity continues to occur without evidence that the electrical activity has depolarized or captured the myocardium. Pacing spikes will occur without capture waveform, such as P wave or QRS complex. *Symptoms depends on the basic dysrhythmia and the pt's condition prior to the pacemaker insertion.

Malsensing

(failure to sense) The pacemaker does not recognize or sense the pt's own inherent heartbeats. May send current to heart during relaxation (repolarization) phase; also known as pacemaker competition with patient's own heart. * With atrial pacing, atrial fibrillation can occur; with ventricular pacing, ventricular tachycardia or ventricular fibrillation can occur.

Pacemaker competition

Competition between the pacemaker generator and the heart's inherent rate over control of the myocardium.

Triggered

Electrical current is sent from the pacemaker generator to the myocardium to cause the depolarization of the myocardial tissue.

Program complication

Sensing capability too low for pacemaker to see normal contractions.

Weak battery complications

Slows firing rates, Less effective sensing capabilities, Less than predetermined electrical current.

Capture

The ability of the heart muscle to respond to electrical stimulation and depolarize the myocardial tissue.

Atrioventricular delay (AV delay)

The measurement from the atrial spike to the ventricular spike, or from the beginning of the P wave to the ventricular spike on a pacemaker tracing. Usually is programmed time frame is somewhere between 0.12-0.20 secs, similar to normal PR interval.

Oversensing

The pacemaker senses electrical current from other muscle movements or electrical activity outside of the body as the patient's heart electrical current. Either (1) the pt's own heart rate is recorded and is slower than the set rate of the pacemaker or (2) the pacemaker spikes and captures at a slower rate than set. *Pt may have signs and symptoms of low CO.

Inherent Rhythm (Intrinsic Rhythm)

The patient's own heart rhythm.

Pacing Spikes

Thin spike on ECG tracing indicates stimulation of electrical current from pacemaker generator. After spike, either a P wave or wide QRS complex or both will appear, depending on which chamber is being paced.

Bundle Branch Block Dysrhythmias (BBB)

When one/both of the ventricular pathways are damaged or delayed due to cardiac disease, drugs, or other conditions. Electrical current is not able to travel through the myocardial tissue in the normal manner. Rhtm: R/IR. AR/VR: depends on basic rhythm. Pw: shape, configuration, deflection, coordination depends on basic rhythm. PR: N. QRS: wider complex. <0.12. *Pt exhibits N effects of basic rhtm. Monitor/ Report esp. with acute MI. Condition can deteriorate to complete heart block. May require Pacemaker/ code blue.

Left Bundle Branch Block (LBBB)

[Current travels down the right bundle branch to cause right ventricle contraction. The current moves to the left ventricles causing the septum to be activated abnormally in a right-to-left fashion.] v1 lead has a negative deflection QRS.

Right Bundle Branch Block (RBBB)

[Septum is depolarized normally, Left Ventricle activated, Current travels to the right Ventricle until there is complete ventricular contraction.] v1 lead has a positive deflection QRS.

Atriobiventricular pacing

commonly used in Pts with heart failure, it stimulates both ventricles to contract instead of the typical stimulation of only the lower portion of the right ventricle.