Which of the following statements about Premature Ventricular Beats is false:
Answer is C (Prevalence decreases with age) The presence of premature complexes increases with age - Braunwald 8th/895 Premature Ventricular Contractions or Premature Ventricular Complexes (VPC's) (Ventricular Premature Beats, Ventricular Ectopic beats) Premature ventricular contractions / complexes are caused by an ectopic impulse that originates in the purkinje fibres distal to the bifurcation of the bundle of His, or in the working ventricular myocardium Such ectopic impulses arising from the ventricles do not enter the conducting pathway and hence do not depolarize both ventricles simultaneously but cause sequential depolarization of ventricles, one ventricle at a time Such sequential depolarization results in abnormal conduction of impulse and causes a wide bizarre QRS complex (> 0.12 sec) Characteristics of PVC's (ECG) The QRS complex is prematuredeg The QRS complex is wide (>0.12 sec)Q and BIZZARE0 or distoed (notched) The QRS complex is not preceded by a P wavee A' P wave is not associated with the PVCe The QRS complex is usually followed by a complete compensatory pausee (The compensatory pause following PVC is frequently complete)e The QRS complex may be monophasic or biphasic (Not Triphasic)e The ST segment and T wave slope in the opposite direction from the main deflection of the QRS complex. e Clinical features The prevalence of PVC increases with Age They arc associated with male gender (Male > Females) May occurs in patients with no cardiovascular abnormalities and in patients with underlying cardiovascular disease Majority of patients are asymptomatic Presenting symptoms include palpitations. lightheadedness, fatigue, near syncope, syncope Prognosis In presence of coronary aery disease (CAD) or history of MI, complex or frequent VPC's are associated with increased risk of sudden cardiac death.
Sequential depolarization of ventricles
Wide, Bizzare, Notched QRS complexes
Prevalence decreases with age
Palpitations is a common presenting feature