Ortho-Preferred

Differentiation SVT vs V Tach


- Definition of V tach: 
- by definition, 4 or more PVCs in a Row; 
- appears as wide QRS usually with Left B.B.B. pattern (as opposed to a narrow complex seen with SVT); 
- may occurs short paroxysm or as sustained run w/ rate between 120-250 BPM; 
- SVT vs VT - aberrant conduction (SVT) is favored w/ Rt BBB shaped QRS complexes at a frequency above 170/min; 
- AV dissociation during tachycardia implies ventricualr origin; 
- ventricular tachycardia is usually regular, but alteration of R-R interval during Tachycardia may occur in both V.Tach & SVT
- QRS width of > 0.14 seconds favors V tach; 
- V. tach is also favored w/ Mono or Biphasic Right Bundle Branch Block
- Shaped QRS complexes in lead V1; 
- an atrial impulse may break thru from above to stimulate 
- normal appearing QRS complex during VT
- if portion of QRS is present = "Fusion Beat"; 
- If there is complete QRS = "Capture Beat"; - presence of "captures" or "fusions" making the diagnosis of VT 



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Friday, December 16, 2011 4:16 pm