Right atrial abnormality

Changes in the size and shape of the P wave can point towards an atrial abnormality, which may be caused by right or left atrial enlargement (Figs. 5.4 and 5.6 respectively) or more rarely a conduction delay. Additional evidence for the presence of an atrial abnormality, enlargement, dilation or hypertrophy is the coexistence of a ventricular hypertrophy. 

Right atrial abnormality, also known as P. pulmonale (Fig. 5.4). This is seen on the ECG as peaked P waves which are greater than 2.5 mm in amplitude (height). Remember each small square of ECG paper is 1 mm, so it s taller than two and half small squares (Fig. 5.5). 

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Right ventricular hypertrophy (Fig. 5.12) is less common than left ventricular hypertrophy. RVH is often accompanied by right atrial abnormality and tall R waves in lead Vi (height of R wave > depth of S wave), and right axis deviation. In more severe cases ST segment depression and T wave inversion, indicating strain pattern can sometimes be seen (Fig. 5.13). 

R wave in Vi + S wave in Ve >10 mm in height Accompanied right atrial abnormality... 

The IV administration of propafenone is accompanied by an increase in right atrial, pulmonary arterial, and pulmonary artery wedge pressures in addition to an increase in vascular resistance and a decrease in the cardiac index. A significant decrease in ejection fraction may be observed in patients with preexisting left ventricular dysfunction. In the absence of cardiac abnormalities, propafenone has no significant effects on cardiac function. 

Bilateral atrial abnormality refers to an abnormality that affects both atria (Fig. 5.9). This can be detected by the combination of indicators for both right and left atrial abnormality, present on the same ECG. Table 5.1 snmmarises some of the key P wave changes present in right, left and bilateral atrial abnormality. 

A 44-year-old woman took an overdose of venlafaxine 3 g. An electrocardiogram showed sinus rhythm and incomplete right bundle branch block (32). She was monitored in an intensive care unit and 10 hours later a further electrocardiogram showed atrial fibrillation with a wide QRS complex. Both of these abnormalities resolved with sodium bicarbonate (100 ml of a 1 M solution). No further conduction disturbances were noted over the following days. 

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