- 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