As a medical professional with expertise in cardiology, I can provide you with an informed response regarding left axis deviation (LAD). It's important to understand that the QRS axis is a term used to describe the average direction of electrical activation through the ventricles of the heart, as seen on an electrocardiogram (ECG). The normal QRS axis should indeed be between -30 and +90 degrees. Left axis deviation, where the QRS axis is between -30 and -90 degrees, can be considered normal in certain circumstances. For example, it is common to see LAD in individuals with a leftward heart position, such as those with a dominant left pectoral muscle or in the case of chronic lung disease which can cause the heart to be pulled to the left. Additionally, LAD can be a normal variant in children and young adults. However, it's also crucial to note that LAD can be associated with certain cardiac conditions, such as coronary artery disease, left ventricular hypertrophy (LVH), or congenital heart disease. Therefore, while LAD can be normal in some cases, it's always important to consider the clinical context and other ECG findings to determine if further investigation or treatment is necessary. read more >>

It can be normal, leftward (left axis deviation, or LAD), rightward (right axis deviation, or RAD) or indeterminate (northwest axis). The QRS axis is the most important to determine. ... The normal QRS axis should be between -30 and +90 degrees.read more >>