An electrocardiogram, commonly known as an ECG or EKG, is a non-invasive test that measures the electrical activity of the heart. Small patches, called electrodes, are placed on the chest, arms, and legs to detect these natural electrical impulses. The ECG machine then records and interprets these signals, providing a graphical representation of the heart’s rhythm and electrical timing. This process helps healthcare providers assess heart function and identify potential issues.
The Heart’s Electrical Axis
The heart’s electrical axis refers to the average direction of the electrical current as it spreads through the ventricles during each heartbeat. This electrical activity originates in specialized cells and travels through a precise conduction system, causing the heart muscle to contract.
A normal heart axis typically falls within a range of -30 to +90 degrees on the ECG’s hexaxial reference system. This range signifies that the electrical activity predominantly moves downwards and to the left, which is the natural pathway for electrical impulses in a healthy heart. In practical terms, a normal axis often presents with positive deflections in leads I and II on the ECG.
Right axis deviation (RAD) indicates a shift in this electrical activity towards the right side of the body, moving beyond the normal range, specifically between +90 and +180 degrees. It contrasts with left axis deviation, where the electrical activity shifts towards the left.
Interpreting Borderline Right Axis Deviation
Borderline right axis deviation means the heart’s electrical axis is slightly outside the typical normal range but not significantly shifted to be classified as full right axis deviation. It occupies a “gray area” where the axis might be, for instance, just over +90 degrees, perhaps around +95 or +100 degrees. This finding suggests a minor deviation that may not always signify a serious underlying problem.
Identifying borderline right axis deviation on an ECG involves analyzing the QRS complex in specific leads. For example, a QRS complex that is negative in lead I but positive in lead aVF can indicate a rightward shift.
Underlying Causes and Health Implications
Borderline right axis deviation can stem from various factors, some of which are benign and others that may warrant further investigation. Physiologically, a vertical orientation of the heart, common in tall and thin individuals, can cause a rightward shift. This also applies to newborns and infants who typically exhibit a rightward axis due to right ventricular dominance at birth.
More significant causes can include conditions that increase the workload on the right side of the heart, leading to changes in its electrical activity. Right ventricular hypertrophy, an enlargement of the right ventricular muscle, is a common pathological cause and can result from conditions like pulmonary hypertension or chronic lung diseases such as COPD. These conditions can cause the right ventricle to generate a stronger electrical signal, shifting the axis.
Additionally, changes in the heart’s conduction pathways or a decrease in the left ventricle’s muscle mass, such as from a lateral myocardial infarction, can also lead to right axis deviation. While borderline RAD can be inconsequential, it can sometimes be an early sign of an underlying issue, especially if accompanied by other symptoms like shortness of breath or chest pain. The presence of other “borderline” ECG findings might also increase concern.
Next Steps After a Diagnosis
The immediate next step is to discuss these results thoroughly with your healthcare provider. This finding is often interpreted in the context of your overall health, symptoms, and medical history.
Further evaluation may be recommended to determine the significance of this finding. This could include a physical examination, a review of any symptoms you might be experiencing, or additional diagnostic tests. An echocardiogram, for example, might be ordered to assess the function of the right ventricle and rule out any structural heart abnormalities.
In some cases, lung function tests may be considered if a lung condition is suspected as a contributing factor. The importance of borderline right axis deviation largely depends on its underlying cause. Often, if no other issues or symptoms are found after a thorough workup, the finding may be deemed a normal variant or not clinically significant, providing reassurance.