Ventricular tachycardia: look for cannon waves and a variable first heart sound

Clinical bottom line (level 4)

  1. Patients with tachycardia who did not have cannon waves in their jugular venous pulse were less likely to have ventricular tachycardia (LR+0.067) .
  2. Patients with a variable first heart sound were more likely to have ventricular tachycardia.
  3. Physicians were not very good at diagnosing or ruling out ventricular tachycardia on physical examination.
Garratt et al: Circulation 1994; 90: 3103-3107
Expires November 2004

The study

Setting: cardiology wards, university hospital, UK

21 patients (aged mean 37, ?% male) with temporary atrial and ventricular pacing wires in-situ

Excluded if
  • evidence of intact atrioventricular conduction
  • discomfort when paced at higher rates



    • Independent blinded reference standard, applied in all patients from a non-consecutive inappropriate spectrum.
    Reference standard:
    • atrial or ventricular pacing to simulate SVT and VT respectively
    Diagnostic test: variability of arterial pulse, jugular venous pulse amplitude, loudness of first heart sound
    • Patients were examined several times by 26 clinicians.

    The evidence


    diagnostic test ventricular tachycardia supraventricular tachycardia LR+
    (95% CI)    		 LR-
    (95% CI)
    physician's prediction 15 6 2.5
    (1.2 to 5.1)     		0.36
    (0.16 to 0.80)
    variable intensity of arterial pulse 12 6 2.0
    (0.94 to 4.3)     		0.57
    (0.31 to 1.05)
    total 20 20


    diagnostic test ventricular tachycardia supraventricular tachycardia LR+
    (95% CI)    		 post-test probability LR-
    (95% CI)    		 post-test probability
    slow independent jugular venous pulse (cannon waves) 23 5 3.8
    (1.8 to 8.2)     		82% 0.06
    (0.01 to 0.38)     		6%
    variable amplitude of first heart sound 14 0 inf
    (1.5 to inf)     		100% 0.42
    (0.26 to 0.67)     		33%
    total 24 20

    Comments

    1. By pre-selecting the arrhythmias, the study does not match normal clinical practice and overestimates the test characteristics.
    2. The study was too small to show any effect the rate of tachycardia had on diagnosis.

    Citation

    1. Garratt CJ, Griffiths MJ, Young G, et al: Value of physical signs in the diagnosis of ventricular tachycardia. Circulation 1994; 90: 3103-3107
    Contributor: Chris Ball and Bob Phillips, November 1999
    Reviewer:

    Clinical Question.
    Patient tachycardia
    Intervention or Exposure physical signs
    Outcome ventricular tachycardia