Ventricular rhythms

The most common arrhythmia in humans is atrial fibrillation. Because of the lack of rhythmic atrial activation, irregular ventricular rhythms and thromboembolism result. There are two possible therapeutic goals ... 

Premature ventricular complexes (PVCs) are common ventricular rhythm disturbances that occur in patients with or without heart disease and may be elicited experimentally by abnormal automaticity, triggered activity, or reentrant mechanisms. 

Atrial fibrillation (AF) is one of the most common rhythm disturbances, and is characterized by the absence of discrete P wave and an irregular ventricular rhythm. Fibrillatory waves are either fine or... 

Flecainide is contraindicated in patients with preexisting second- or third-degree heart block or with bundle branch block unless a pacemaker is present to maintain ventricular rhythm. It should not be used in patients with cardiogenic shock. 

Atrial fibrillation is an arrhythmia in which the electrical activity in the atria is disorganised. The AV node receives more electrical impulses than it can conduct and most are blocked resulting in an irregular ventricular rhythm. 

Q8 Depolarization of the atria normally gives rise to one P wave which precedes the QRS complex and a coordinated atrial contraction. In fibrillation the cardiac impulses arise abnormally and discharge at a very high rate (>350 min-1), producing a fast series of small, irregular waves before the QRS complex of the ECG. When this happens, the atria are unable to contract in a coordinated manner. Only occasional impulses can move through to the AV node to excite the ventricle, and ventricular rhythm becomes irregular. Patients become aware of the abnormal ventricular rhythm and usually describe the sensation as palpitations . 

An accelerated ventricular rhythm, which is defined as a ventricular rhythm with a rate higher than the escape ventricular rhythm rate and lower than the ventricular tachycardia rate (between 25-40 bpm and 90-110 bpm), usually occurs in runs that cease spontaneously and is well tolerated. It sometimes occurs during reperfusion (see p. 228 Figures 8.16 and 8.17) and generally does not require a specific treatment. 

Because of the results of the Cardiac Arrhythmia Suppression Trials and other trials, antiarrhythmic drugs (except /3-blockers) should not be used routinely in patients with prior myocardial infarction (Ml) or left ventricular (LV) dysfunction and minor ventricular rhythm disturbances (e.g., premature ventricular complexs). 

Daoud EG, Weiss R, Bahu M, et al. Effect of an irregular ventricular rhythm on cardiac output. Am J Cardiol 1996 78 1433-6. 

EoUowing ceU grafting, a new ectopic ventricular rhythm was detected in 11 out of 13 animals studies, in six of which it was characterized by sustained and long-term activity. Three-dimensional electrophysiological... 

Nathanson and Miller (49) administered allocryptopine orally (100 mg. twice daily) to a patient with frequent ventricular extra systoles. After therapy there was a reduction in the number of extra systoles. A case of ventricular tachycardia responded to 100 mg. of allocryptopine. A patient with auricular flutter received 100 mg. of allocryptopine there was then a bigeminal rhythm with multifocal ventricular rhythm and the patient died. 

Atrial Flutter Ectopic focus of atrial cells generates 250-350 impulses per minute. The ventricle responds to every 2nd or 3rd impulse. Both atrial and ventricular rhythm are regular. 

The treatment of type I AIT consists of simultaneous administration of thionamides and perchlorate. If possible, a temporary amiodarone-withdrawal should be tried, especially in AIT type I, because amiodarone-induced hyperthyroidism may remit spontaneously within 6 months (Kahaly et ai, 2006 Kennedy et aL, 1989 Rajeswaran et ai, 2003). However, amiodarone therapy often cannot be stopped when life-threatening ventricular rhythm disturbances persist. 

A. The presence of nodal or ventricular rhythms in the setting of third-degree atrioventricular or intraventricular block. These are usually reflex escape rhythms that may provide lifesaving cardiac output, and abolishing them may result in asystole. 

Propafenone, l- 2-[2-hydroxy-3-(propylamino)propoxy]phenyl -3-phenylpropan-l-one, is a conunonly used sodium and potassium channel blocker for the treatment of ventricular tachycardia and atrial fibrillation [15]. Propafenone hydrochloride is a class IC antiarrhy tmic agent that shows structural similarity and activity related to p-adrenoly tic agents. The drug is efficacious in suppressing supraventricular and ventricular rhythm disorders [15] (Figure 14.12). 

Toivonen L, Viitasalo M, Jarvinen A. The performance of the probability density function in differentiating supraventricular from ventricular rhythms. Pacing Clin Electrophysiol 1992 15 726-30. 

Fig. 19.2 Assessment of pacemaker dependency, (a) Totally paced ventricular rhythm when the base rate is reduced to 30 ppm in a nontracking (DDI) mode in a patient who has asystoUc complete heart The P waves that occur during the atrial alert period are identified by event markers as are all the ventricular paced complexes, (b) Underlying 2 1 block rhythm is identified in a patient with a DDD pacemaker whose ventricle is normally totally controlled by the permanent pacemaker. To show this, the mode was temporarily changed to VVI and the pacing rate reduced to 30 ppm. The simultaneously telemetered unipolar atrial electrogram is shown along the bottom demonstrating the atrial activity as well as far-field ventricular signals.

VT can coexist with AF (see below). A giveaway to the interpreter that VT may be present is a completely regular fast ventricular rhythm whose morphology is unlike that during baseline rhythm. 

Q What effect did the ICD have on the ventricular rhythm below ... 

The AEGM clearly displays AF however, the VBGM shows a completely regular fast ventricular rhythm. Thus the patient likely had dual tachycardias, AF and VT Both rhythms were converted by the shock. 

Move the paper across the strip lining up the two marks with succeeding R-R intervals. If the distance for each R-R interval is the same, the ventricular rhythm is regular. If the distance varies, the rhythm is irregular. 

Ventricular rhythms originating in the left ventricle Posterior Myocardial Infarction (MI) Wolff-Parkinson-White syndrome (WPW) Dextrocardia... 

There is one incidence where AF may appear regular rather than irregularly irregular and this is in the presence of 3rd degree AV block. No P waves are visible and the characteristic undulating chaotic baseline of AF can be seen but with a regular ventricular rhythm (Fig. 7.12). 

If R-R intervals are consistently similar, ventricular rhythm is regular. 

You can use eHher of the following methods to determine atrial or ventricular rhythm. 

---