This document discusses different types of arrhythmias, or irregular heart rhythms, including tachyarrhythmias (fast rhythms) and bradyarrhythmias (slow rhythms). It describes specific conditions like ventricular fibrillation, atrial fibrillation, various types of heart block, and paroxysmal supraventricular tachycardia. The document also lists factors that can predispose patients to arrhythmias and notes that immediately life-threatening rhythms include ventricular fibrillation, pulseless ventricular tachycardia, and ventricular asystole.

1. Too fast or too slow.
A Bit About Life Threatening Arrhythmias.
Dr LNR González
Robert Mangaliso Sobukwe Hospital(Kimberley Hospital)May 2020.

2. Types of Arrhythmias Tachyarrhythmias
• Tachycardia is a condition that makes your heart beat more than 100
times per minute:
Supraventricular. This happens when the electrical signals in the
hearts upper chambers misfire and cause the heart rate to speed up.
It beats so fast that it can’t fill with blood before it contracts. That
reduces blood flow to the rest of the body.
Ventricular. This is a rapid heart rate that starts in your heart's lower
chambers. It happens when the electrical signals in these chambers
fire the wrong way. Again, the heart beats so fast that it can’t fill with
blood or pump it through the rest of the body.

3. Types of Bradyarrhythmia's
• Bradycardia is a heart rate that’s too slow. In general, for adults, a resting
heart rate of fewer than 60 BPM qualifies as bradycardia. There are several
types:
Sinus bradycardia. When a person has sinus bradycardia, the heart rate is
less than 60 beats per minute. This slow heart rate might be normal. This
type of slow heart rate is often seen in healthy, athletic people.
Sinus pause (also called sinus arrest).During a sinus pause, the heart may
miss one or more beats because its natural pacemaker fails to activate the
electrical system throughout the rest of the heart..
AV blocks. Refers to an abnormality in the way electricity passes through
the normal electrical pathways of the heart. The abnormality "blocks" the
electrical impulse from continuing through the normal pathways and
usually results in a slower heart rate.

4. Immediately Life Threatening in any Patient
Arrhythmias that are immediately life-threatening in any patient
include the following:
 Ventricular fibrillation (VF)
 Pulseless ventricular tachycardia (PVT)
 Ventricular asystole
 Pulseless electrical activity (electromechanical dissociation)…….
In general:
Any symptomatic fast rhythm
Any symptomatic brady

5. Predisposing Conditions
• Primary cardiac disease :CAD,Cardiomyopathy, valvular heart disease, neoplasia, congenital,
• Thoracic trauma: Blunt, penetrating, electrical.
• Hypoxia :Respiratory disease, anaemia, thromboembolic disease, anaesthesia, hypoperfusion.
• Electrolyte/acid-base disorders : Potassium imbalance, calcium imbalance, magnesium
imbalance, acidosis.
• Endocrine disease : Hypoadrenocorticism, hyperthyroidism, hypothyroidism, pheochromocytoma,
diabetic ketoacidosis.
• Autonomic imbalance: Catecholamine excess, central nervous system (CNS) disease, vagal
stimulation.
• Temperature: Hypothermia, hyperthermia .
• Inflammation: Infection, sepsis, systemic inflammatory response syndrome (SIRS), immune-
mediated disease
• Drugs: Antiarrhythmic drugs, positive inotropic agents, anaesthetic agents, sedatives.

6. Any differences in the criteria to consider a
brady or tachy to be unstable?

7. Ventricular Fibrillation
• Ventricular fibrillation is often a fatal arrhythmia. It occurs when the
ventricular rate exceeds 400. In this setting, virtually no forward
cardiac output occurs. Advanced Cardiac Life Support (ACLS) should
be instituted immediately, including emergent electrical
cardioversion.

8. Ventricular Tachycardia
• Ventricular tachycardia rhythm is primarily identified by several
criteria. First, the rate is usually greater than 180 beats per minute,
and the rhythm generally has a very wide QRS complex. Ventricular
tachycardia starts in the heart's lower chambers.

9. Torsades de Pointes
• In torsade, the morphology of the QRS complexes varies from beat to
beat. The ventricular rate can range from 150 beats per minute (bpm)
to 250 bpm.

10. Ventricular Asystole
• Asystole is also known as flatline. It is a state of cardiac standstill with
no cardiac output and no ventricular depolarization, as shown in the
image below; it eventually occurs in all dying patients.

11. Ventricular Premature Complexes
• Premature ventricular contractions (PVCs) are extra heartbeats that
begin in one of the heart's two ventricles. These extra beats disrupt
your regular heart rhythm, sometimes causing you to feel a fluttering
or a skipped beat in your chest.

12. Paroxismal SVT
• Paroxysmal Supraventricular Tachycardia (SVT, PSVT) Paroxysmal
supraventricular tachycardia is a regular, fast (160 to 220 beats per
minute) heart rate that begins and ends suddenly and originates in
heart tissue other than that in the ventricles.

13. Atrial Fibrillation
• Atrial fibrillation is an irregular and often rapid heart rate that occurs
when the two upper chambers of your heart experience chaotic
electrical signals. The result is a fast and irregular heart rhythm. The
heart rate in atrial fibrillation may range from 100 to 175 beats a
minute.

14. Atrial Flutter
• Well-organized but overly rapid contractions of the atrium of the
heart (usually at a rate of 250-350 contractions per minute). Flutter
refers to a rapid vibration or pulsation. The difference between flutter
and fibrillation is that flutter is well organized while fibrillation is not.

15. 1st Degree AV Block
• First-degree atrioventricular (AV) block is defined as a PR interval of
greater than 0.20 seconds on electrocardiography (ECG) without
disruption of atrial to ventricular conduction . It is generally
asymptomatic and without significant complications.

16. 2nd Degree AV block Type I
• Type 1 Second-degree AV block, also known as Mobitz I or
Wenckebach periodicity, is almost always a disease of the AV node. ...
Today, Mobitz I heart block is characterized by progressive
prolongation of the PR interval on consecutive beats followed by a
blocked P wave (i.e., a dropped QRS complex).

17. 2nd Degree AV block Type II
• Second-degree AV block (Type 2) is almost always a disease of the
distal conduction system located in the ventricular portion of the
myocardium. The QRS on an ECG will most likely be wide because the
block occurs in the His bundle or bundle branches and conduction
through the ventricles is slowed.

18. 3RD Degree AV Block
• Typically the patient will have severe bradycardia with independent
atrial and ventricular rates, i.e. AV dissociation.

19. Paroxysmal Supraventricular Tachycardia
• Paroxysmal supraventricular tachycardia is a regular, fast (160 to 220
beats per minute) heart rate that begins and ends suddenly and
originates in heart tissue other than that in the ventricles. Most
people have uncomfortable awareness of heartbeats (palpitations),
shortness of breath, and chest pain.

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