Electrocardiogram (ECG)
What Is An ECG?
An electrocardiogram (also called an EKG or ECG) is a test that records the timing and strength of the electrical signals that make the heartbeat. By looking at an ECG, doctors can gain insights into the heart's rhythm and look for irregularities.
How Apple Watch Takes an ECG
Since Series 4, Apple Watch has featured a built-in electrical heart sensor. * The Circuit: The back crystal touches your wrist, and your finger touches the Digital Crown. This creates a closed circuit across your chest, allowing the watch to measure electrical impulses across your heart. * Single-Lead: This is equivalent to a Lead I ECG in a clinical setting. It can detect rhythm (Regular vs. Irregular) but cannot detect heart attacks, structural defects, or ischemia (which require a 12-lead clinical ECG).
سائنسی پس منظر
The Apple Heart Study (NEJM 2019)
To validate the technology, Apple and Stanford Medicine conducted the Apple Heart Study, the largest of its kind, with over 400,000 participants. The results were published in the New England Journal of Medicine.
Key Findings: * Accuracy: The irregular rhythm notification showed a 0.84 positive predictive value for Atrial Fibrillation (Afib). This means that if the watch said "irregular," 84% of the time Afib was actually present during concurrent monitoring. * Utility: It demonstrated that wearable technology could safely aid in the identification of Atrial Fibrillation, a leading cause of stroke.
"The study provides evidence that a smartwatch application can identify pulse irregularity... which may aid in initial identification of atrial fibrillation." — Perez et al., NEJM, 2019
طبی اہمیت
Atrial Fibrillation (Afib)
The primary condition consumer ECGs look for is Atrial Fibrillation. * What it is: The upper chambers (atria) beat chaotically and irregularly, out of coordinate with the lower chambers (ventricles). * The Risk: Blood can pool in the atria, form clots, and travel to the brain, causing a stroke. Afib is responsible for approximately 20-30% of all strokes. * Silent Afib: Many people have brief episodes of Afib without feeling it. The watch can capture these asymptomatic events.
حدود (What It Can't Do)
The Apple Watch ECG app is FDA-cleared, but it has strict limitations. It cannot detect: * Heart attacks (Myocardial Infarction) * Blood clots * High blood pressure * Congestive heart failure * Other arrhythmias (like ventricular tachycardia)
سفارشات
When to Take an ECG
- Symptoms: If you feel a "flutter," rapid heartbeat, or skipped beat.
- Notifications: If you receive an "Irregular Rhythm Notification" or "High/Low دل کی دھڑکن" alert.
- Routine: Occasionally (e.g., once a month) if you have risk factors, but taking it daily without symptoms is generally unnecessary for healthy adults.
Interpreting Results
- Sinus Rhythm: Your heart is beating in a uniform pattern between 50 and 100 BPM. This is normal.
- Atrial Fibrillation: An irregular pattern was detected. This requires medical follow-up.
- Low or High دل کی دھڑکن: The HR is <50 or >100 BPM (check "دل کی دھڑکن" section for context).
- Inconclusive: The reading couldn't be classified (often due to movement, poor contact, or complex arrhythmias). This is not a diagnosis of a problem, just a failed reading.
حوالہ جات
- Perez MV, et al. (2019) Large-Scale Assessment of a Smartwatch to Identify Atrial Fibrillation. New England Journal of Medicine, 381:1909-1917.
- Turakhia MP, et al. (2019) Rationale and design of a large-scale, app-based study to identify cardiac arrhythmias using a smartwatch: The Apple Heart Study. American Heart Journal, 207:66-75.
- Bumgarner JM, et al. (2018) Smartwatch Algorithm for Automated Detection of Atrial Fibrillation. Journal of the American College of Cardiology, 71(21).