Hello my name is Timmecia Smith and I will discuss heart rate and rhythm this week.
Heart is under the control of sympathetic and parasympathetic nervous system.
Sympathetic nervous system activates the heart and parasympathetic nervous system does
the opposite. The cardiac impulse is originated from the pacemaker of the heart that is
called SA node. SA node is under the control of autonomic nervous system. When the
impulse is originated from the SA node, it is called normal sinus rhythm. Normal heart
rate ranges from 60 bpm to 100 bpm. Heart rate less than 60 bpm is called bradycardia
and heart rate above 100 bpm is called tachycardia. Disturbance in the normal sinus
rhythm is called arrhythmia. Normal sinus rhythm is represented by the presence of P
wave before each QRS complex.
Normal ECG
Arrhythmias are further classified on the basis of heart rate and rhythm regularity. Brady
arrhythmias are the disturbance in heart rhythm with the heart rate below 60 bpm and
tachyarrhythmia’s are the ones with heart rate above 100 bpm. Brady arrhythmias are of
many types. Some of the common types are 2nd and 3rd degree heart block, sick sinus
syndrome which is also called tachybrady syndrome.
Tachyarrhythmia’s are classified whether they are originating from the atria or the
ventricles. When the rhythm is originating from the atrium, it is called atrial tachycardia
or supraventricular tachycardia’s. supraventricular tachycardia can be atrial fibrillation,
atrial flutter, AV nodal re-entrant tachycardia and wolf Parkinson white syndrome. All of
these tachycardia have the common symptoms of palpitation, chest tightness, dyspnea
etc. They are identified on doing the ECG in emergency room.
Ventricular tachycardia and ventricular fibrillation are the two common arrhythmias
arising from the ventricle. Ventricular tachycardia is a broad QRS complex tachycardia
that has regular R-R interval while ventricular fibrillation is the irregular haphazard QRS
with no definite morphology and leads to death within seconds if not treated swiftly. Here
are the some arrhythmia and their ECGs.
Ventricular Tachycardia
Atrial Fibrillation
Complete heart block
AV nodal re-entrant tachycardia
References
1- Supraventricular tachycardia - AV nodal reentry. (n.d.). Elentra.healthsci.queensu.ca.
Retrieved July 19, 2023, from
https://elentra.healthsci.queensu.ca/assets/modules/ECG/supraventricular_tachycardia__a
v_nodal_reentry.html
2- Types of Arrhythmias - Mount Sinai Heart | Mount Sinai - New York. (n.d.). Mount Sinai
Health System. https://www.mountsinai.org/care/heart/services/arrhythmia/types