Abnormal ventricular activation in Wolff-Parkinson-White Syndrome (WPW) can be identified by echocardiography, but the effects of premature ventricular contractions have not been demonstrated. We examined motion of the interventricular septum (IVS) and left ventricular posterior wall (LVPW) by surface echocardiography in 12 awake dogs using a method developed and validated in our laboratory. Premature ventricular contractions (PVCs) were induced by right (RV) and left ventricular (LV) pacing (6 dogs), injection of dopamine (2 dogs) and phenylephrine (2 dogs), and posterior myocardial infarction (MI) caused by embolization of the circumflex coronary artery (2 dogs), and posterior myocardial infarction (MI) caused by embolization of the circumflex coronary artery (2 dogs). PVCs induced by RV and LV septa’ pacing showed early IVS systolic posterior motion beginning 40.0 msec (range 26-48 msec) after the pacing impulse, while LVPW showed normal motion beginning 78.8 msec (range 63-116 msec) after the pacing impulse and accompanied by decreased posterior IVS motion. PVCs induced by LVPW pacing demonstrated early LVPW systolic anterior motion beginning 43.3 msec (range 31-68 msec) after the pacing impulse, while IVS showed a normal motion which began 97.3 msec (range 76–130 msec) after the pacing impulse and was accompanied by reduced anterior motion of the LVPW. PVCs induced by dopamine and phenylephrine showed a similar echocardiographic pattern to RV and LV septal pacing, while PVCs induced by MI exhibited a pattern similar to LVPW pacing. This study demonstrates that early IVS or LVPW contraction can be demonstrated by echocardiogram, and also indicates where the site of early excitation after PVCs is.
- Posterior wall of the left ventricle
- Premature ventricular contraction
- interventricular septum