Category:Altered Ventricular Impulse Formations

Small Animals: Not as common as atrial abnormalities

Large Animals: Uncommon

1. Ventricular Tachycardia

• A rapid, regular heart beat caused by continuous ventricular premature complexes (VPCs).

• Serious condition which has the capability of causing ventricular fibrillation and ultimately death

Causes

Significant myocardial damage to the heart or disease in other systems, Drug reactions, Hypoxia, Anaemia, Electrolyte and acid-base disturbances, etc.

ECG Appearance: Wide and irregular QRS complexes, P waves without QRS complexes following

Treatment

Treat underlying conditions

Small Animals

Dog: lidocaine (1st line of treatment), quinidine or procainamide (2nd line of treatment)

Cat: propranolol (1st line of treatment), small dose of lidocaine (2nd line of treatment)

Large Animals

• Digitalis

• Quinidine Sulfate

• Magnesium Sulfate supplementation (used in horses)

2. Ventricular Premature Complexes (VPCs)

• An ectopic beat beginning in the ventricles below the AV node and occurring prematurely in relation the the existing cardiac rhythm.

• Often VPCs are following by a compensatory pause.

Causes

Significant myocardial damage to the heart or disease in other systems, Drug reactions, Hypoxia, Anaemia, Electrolyte and acid-base disturbances, etc.

ECG Appearance: P waves absent from the QRS complexes associated with the VPCs, wide and abnormal QRS complexes

Treatment

Treatment similar to ventricular tachycardia.

3. Ventricular Fibrillation

• Total lack of organized ventricular depolarization causing cardiopulmonary arrest and death.

Causes

Cardiac or systemic pathology, Electrolyte disturbances, Electric Shock, Untreated ventricular tachycardia, Hypoxia etc.

ECG Appearance: Wavy baseline without any sign of an organized P, QRS, or T wave

Treatment

Small Animals

• Cardiopulmonary resuscitation: electrical defibrillation, open-chest cardiac massage, intratracheal lidocaine

Large Animals

• Rarely detected in large animals before death

• There is no treatment for large animals with this condition

4. Ventricular Asystole

• The complete absence of electrical cardiac activity

====Causes====Cardiac or systemic pathology, Electrolyte disturbances, Electric Shock, Untreated ventricular tachycardia, Hypoxia etc.

ECG Appearance: Flat base line

Treatment

Small Animals

• Cardiopulmonary resuscitation

• Epinephrine

5. Escape Rhythms

• These rhythms occur in an effort to maintain heart function when the SA or AV nodes are not functioning properly. Escape rhythms occur in pacemaker tissue found in the atria, around the AV node, or in the ventricles. These ectopic rhythms occur at a regular, but slower depolarization rate compared to the dominant SA and AV nodal pacemakers.

ECG Appearance: Depending on where the escape rhythms originate, they can appear either as ectopic beats with a normal or totally abnormal shape.

====Treatment==== Do not use antiarrhythmic drugs in the presence of escape rhythms or else you risk death.

Category:Impulse Conduction Abnormalities