Changes

'''Ventricular tachycardia''' (VT) is a '''rhythm disturbance''' classified as '''four or more [[Ventricular Premature Complexes|ventricular premature complexes]] (VPC's) in sequence''', producing a '''rapid''' heart rate. It is a serious condition which has the capability of causing '''[[Ventricular Fibrillation|ventricular fibrillation]]''' and '''sudden death'''. It most commonly occurs secondary to an existing systemic or cardiac abnormality. It is classed as a '''grade 4''' rhythm disturbance because it is '''electrically unstable''' and causes '''haemodynamic compromise'''.

'''Ventricular tachycardia''' (VT) is a '''rhythm disturbance''' classified as '''four or more [[Ventricular Premature Complexes|ventricular premature complexes]] (VPC's) in sequence''', producing a '''rapid''' heart rate. It is a serious condition which has the capability of causing '''[[Ventricular Fibrillation|ventricular fibrillation]]''' and '''sudden death'''. It most commonly occurs secondary to an existing systemic or cardiac abnormality. It is classed as a '''grade 4''' rhythm disturbance because it is '''electrically unstable''' and causes '''haemodynamic compromise'''.

=Small Animals=

==Small Animals==

It is particularly common in '''Dobermanns''' secondary to '''[[Dilated Cardiomyopathy|Dilated CardioMyopathy]]''' and in the '''Boxer''' secondary to '''Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)'''. The rhythm disturbance is much less common in cats and normally the result of end-stage cardiomyopathy.

It is particularly common in '''Dobermanns''' secondary to '''[[Dilated Cardiomyopathy|Dilated CardioMyopathy]]''' and in the '''Boxer''' secondary to '''Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)'''. The rhythm disturbance is much less common in cats and normally the result of end-stage cardiomyopathy.

==Causes==

===Causes===

* Significant '''structural damage to the heart, heart failure''' or a '''breed specific myopathy'''

* Significant '''structural damage to the heart, heart failure''' or a '''breed specific myopathy'''

* '''Systemic disease''' such as hypoxia, [[Anaemia|anaemia]], electrolyte and acid-base disturbances, [[Hyperthyroidism|hyperthyroidism]] (cats) etc.

* '''Systemic disease''' such as hypoxia, [[Anaemia|anaemia]], electrolyte and acid-base disturbances, [[Hyperthyroidism|hyperthyroidism]] (cats) etc.

* '''Drug reactions'''  

* '''Drug reactions'''  

==Clinical Signs==

===Clinical Signs===

On cardiac auscultation, '''heart rate is abnormally high''' (>160-180 in dogs). There may be signs of '''haemodynamic compromise''' and '''output failure''' such as collapse, hypotension, syncope and congestive heart failure. '''Sudden death''' may be the only presenting sign, especially in predisposed breeds.

On cardiac auscultation, '''heart rate is abnormally high''' (>160-180 in dogs). There may be signs of '''haemodynamic compromise''' and '''output failure''' such as collapse, hypotension, syncope and congestive heart failure. '''Sudden death''' may be the only presenting sign, especially in predisposed breeds.

==Diagnosis==

===Diagnosis===

The condition can be diagnosed by '''[[ECG]]'''. The ECG shows''' wide and bizarre QRS complexes''' and '''P waves that are not consistency related''' to the QRS complexes. Heart rate should be '''high (>160-180 in dogs)'''. QRS complexes can be '''monomorphic''' (similar in appearance with a regular R-R interval) or '''polymorphic''' (variable appearance and irregular R-R interval). A polymorphic appearance is suggestive of a more unstable myocardium. The P-P interval should be regular.

The condition can be diagnosed by '''[[ECG]]'''. The ECG shows''' wide and bizarre QRS complexes''' and '''P waves that are not consistently related''' to the QRS complexes. Heart rate is '''high (>160-180 in dogs)'''. QRS complexes can be '''monomorphic''' (similar in appearance with a regular R-R interval) or '''polymorphic''' (variable appearance and irregular R-R interval). A polymorphic appearance is suggestive of a more unstable myocardium. The P-P interval should be regular.

Sustained Ventricular Tachycardia lasts for more than 30 seconds, unsustained VT lasts less than thirty seconds.  

Sustained Ventricular Tachycardia lasts for more than 30 seconds, unsustained VT lasts less than thirty seconds.  

==Treatment==

===Treatment===

The underlying cause should be identified and treated where possible.  

The underlying cause should be identified and treated where possible.  

Following 1st line treatment, serum [[Potassium|potassium]] levels should be assessed and corrected if necessary.  

Following 1st line treatment, serum [[Potassium|potassium]] levels should be assessed and corrected if necessary.  

==Prognosis==

===Prognosis===

Prognosis depends on the underlying cause of the arrhythmia and the success of its treatment.

Prognosis depends on the underlying cause of the arrhythmia and the success of its treatment.

=Large Animals=

==Large Animals==

Ventricular tacycardia is most likely to be diagnosed and treated in the '''horse'''.

Ventricular tacycardia is most likely to be diagnosed and treated in the '''horse'''.

==Causes==

===Causes===

VT normally occurs secondary to '''myocardial disease, endotoxaemia or electrolyte and acid-base abnormalities'''. It can also occur idiopathically.  

VT normally occurs secondary to '''myocardial disease, endotoxaemia or electrolyte and acid-base abnormalities'''. It can also occur idiopathically.  

==Clinical Signs==

===Clinical Signs===

Cardiac auscultation should reveal an '''abnormally high heart rate'''. There may also be a history of exercise intolerance and dyspnoea.  

Cardiac auscultation should reveal an '''abnormally high heart rate'''. There may also be a history of exercise intolerance and dyspnoea.  

==Diagnosis==

===Diagnosis===

The condition can be diagnosed by '''[[ECG]]'''. The ECG shows a '''fast heart rate with wide and bizarre QRS complexes''' and '''P waves that are not consistency related''' to the QRS complexes. QRS complexes can be '''monomorphic''' (similar in appearance with a regular R-R interval) or '''polymorphic''' (variable appearance and irregular R-R interval). A polymorphic appearance is suggestive of a more unstable myocardium. The P-P interval should be regular.

The condition can be diagnosed by '''[[ECG]]'''. The ECG shows a '''fast heart rate with wide and bizarre QRS complexes''' and '''P waves that are not consistency related''' to the QRS complexes. QRS complexes can be '''monomorphic''' (similar in appearance with a regular R-R interval) or '''polymorphic''' (variable appearance and irregular R-R interval). A polymorphic appearance is suggestive of a more unstable myocardium. The P-P interval should be regular.

Sustained Ventricular Tachycardia lasts for more than 30 seconds, unsustained VT lasts less than thirty seconds.  

Sustained Ventricular Tachycardia lasts for more than 30 seconds, unsustained VT lasts less than thirty seconds.  

==Treatment==

===Treatment===

'''Exercise''' should '''not''' be continued whist the horse has VT.

'''Exercise''' should '''not''' be continued whist the horse has VT.

*Procainamide (in the conscious horse) or lidocaine (in the unconscious horse)  

*Procainamide (in the conscious horse) or lidocaine (in the unconscious horse)  

*Quinidine Gluconate

*Quinidine Gluconate

*Magnesium Sulfate supplementation  

*Magnesium Sulfate supplementation  

==Prognosis==

===Prognosis===

VT can progress to a '''fatal arrhythmia''' (ventricular fibrillation). Prognosis depends on the underlying cause of the arrhythmia and the success of its treatment.

VT can progress to a '''fatal arrhythmia''' (ventricular fibrillation). Prognosis depends on the underlying cause of the arrhythmia and the success of its treatment.

[[Category:Altered Ventricular Impulse Formations]][[Category:To_Do_-_Cardiovascular]]

[[Category: To Do - Siobhan Brade]]

[[Category:Altered Ventricular Impulse Formations]]

[[Category:To Do - Manson review]]

[[Category:Expert Review]]