Aortic insufficiency

ECG 1: Sinus rhythm; pattern of diastolic ventricular hypertrophy with narrow q waves in leads I, aVL, V3-V6, increase in R wave amplitude in V5, V6, increase in S wave amplitude in V1, V2, positive T waves in left precordial leads; ultrasound showed significant aortic insufficiency with moderate left ventricular hypertrophy;

Patient 2: 63-year-old woman with rheumatoid arthritis in childhood, not followed since; hospitalization for cardiac decompensation;

ECG 2: Sinus rhythm; major systolic left ventricular hypertrophy (very significant increase in voltages: R waves in V4-V6, S waves in V1-V2); biatrial enlargement; repolarization disorders (negative T waves in leads I, aVL, II, III, AVF, V4-V6); cardiac ultrasound revealed a very severe aortic insufficiency with dilatation of the cavity and major left ventricular hypertrophy;

Comments: Aortic insufficiency is caused by incomplete closure of the aortic valves, resulting in left intraventricular diastolic regurgitation (reflux of blood from the aorta to the left ventricle during diastole). Aortic insufficiency can be acute and of rapid onset (bacterial endocarditis, aortic dissection and traumatic rupture) but is most often a chronic condition that may be due to multiple etiologies (syphilis, ankylosing spondylitis, ascending aortic diseases, etc.) the most common cause of which is acute articular rheumatism.

The main consequence of aortic regurgitation is a volumetric overload of the left ventricle with an increase in ejected systolic volume leading to dilatation of the cavity and hypertrophy which can potentially become considerable. Left atrial overload is of lesser extent and occurs later. Major leakage can be accompanied by functional coronary insufficiency, with low blood pressure in diastole (myocardial vascularization period) and increased myocardial oxygen requirements (left ventricular dilatation and hypertrophy).

Electrocardiographic patterns reflect the pathophysiological conditions described above, and are more influenced by the degree and age of the regurgitation than by the etiology and are dominated by a left ventricular hypertrophy. Various abnormalities can be observed in chronic aortic insufficiency:

• The tracing can remain strictly normal at the onset of the disease;
• Rhythm is mostly sinus; the occurrence of an atrial arrhythmia (atrial fibrillation) is generally delayed, corresponds to a significant and older leakage and should systematically trigger the search for the presence of associated mitral valve disease;
• Similarly, the presence of left atrial enlargement is rare and only observed in older and severe forms; the pattern of the P wave is therefore usually normal;
• The most characteristic sign of chronic aortic insufficiency is evidence of left ventricular hypertrophy which is proportional to the severity and the duration of the regurgitation: QRS complexes are not altered in the case of a recent small volume leakage, whereas the signs of hypertrophy become typical for a massive and long-lasting leak with a net increase in voltages in V6 corresponding to depolarization of the left ventricular free wall (tall R waves in V5, V6) and in the septum (deep Q waves in V5, V6); hemodynamic overload occurs in diastole, it is thus logical to expect a typical pattern of diastolic ventricular hypertrophy: in V5, V6, narrow and deep Q waves, large R waves, positive T waves; however, this pattern is found only in 25 to 30% of cases and preferentially in the early stages of the disease (minor hypertrophy); due to an overload ultimately mixed (diastolic and systolic) and a subepicardial ischemia, the T wave often becomes negative (sometimes peaked and symmetrical) in V5, V6 (70 to 75% of cases ) in advanced forms; the pattern becomes very similar to that observed during a systolic overload (example of aortic stenosis); a delayed intrinsicoïd deflection is frequently observed in V5, V6;
• The QRS axis may be normal or deviated to the left;
• An incomplete left bundle branch block is relatively frequent in the assessed forms (widening of the QRS, disappearance of the septal activation q wave in V5, V6); the mechanism involved could be an aggression of the left branch network by the regurgitation jet at the junction of the fibrous and muscular portions of the septum;
• The ST segment is generally isoelectric; the presence of a U wave (negative deflection of small amplitude following the T wave) in leads V4 to V6 is frequently observed;
• The occurrence of a first degree atrioventricular block is relatively frequent and can be explained by a regurgitation jet lesion; however, the presence of an abscess of the aortic annulus should be investigated in a patient with infectious endocarditis;

Take-home message: Left ventricular hypertrophy that is initially diastolic and subsequently mixed (systolic and diastolic) is the electrical sign characteristic of chronic aortic insufficiency.