This composite educational illustration combines an anatomical diagram of the human heart with a diagnostic Electrocardiogram (ECG) tracing to demonstrate cardiac physiology. On the left, a coronal cross-section of the heart identifies the Aorta, Right Atrium, Left Atrium, Right Ventricle, and Left Ventricle. The right side features a detailed ECG waveform analysis set against a standard measurement grid (1 square = 0.04 sec / 0.1 mV). The tracing identifies key electrophysiological components: the P wave (atrial depolarization), QRS complex (ventricular depolarization), and T wave (ventricular repolarization). Critical diagnostic intervals and segments are explicitly labeled, including the PR interval, PR segment, QRS interval, ST segment, ST interval, QT interval, and the RR interval (representing the heart rate). This comparison chart and pathophysiology diagram serve as an introductory resource for understanding the correlation between cardiac anatomy and the electrical signals recorded during a cardiac cycle, suitable for basic to intermediate medical education.

A 12-lead electrocardiogram (ECG) printed on standard grid paper (25 mm/sec, 10 mm/mV) demonstrating diagnostic features of cardiac pathology. The ECG shows a regular rhythm with a heart rate exceeding 100 beats per minute, consistent with sinus tachycardia. Key findings include high-voltage QRS complexes in the precordial leads and limb leads (notably I, II, III, and aVF), which meet voltage criteria for Left Ventricular Hypertrophy (LVH). Additionally, there is prominent T-wave inversion observed in the lateral precordial leads (V4, V5, and V6), a finding that can be associated with LVH 'strain' patterns or myocardial ischemia in the clinical context of aortic dissection and hypertension. The trace displays standard lead placement including limb leads (I, II, III, aVR, aVL, aVF) and precordial leads (V1-V6), with a rhythm strip provided at the bottom (Lead II). This visual is representative of the electrical manifestations of structural heart disease secondary to hypertensive or valvular complications.

This diagnostic image shows a standard 12-lead electrocardiogram (ECG) printed on red-grid thermal paper. The recording displays limb leads (I, II, III), augmented vector leads (aVR, aVL, aVF), and precordial leads (V1-V6), accompanied by a continuous rhythm strip of Lead II at the bottom. The tracing demonstrates a normal sinus rhythm with consistent P-wave morphology preceding each QRS complex, followed by regular T-waves. All intervals, including the PR and QT intervals, appear within physiological limits for a healthy human heart. Lead V1 shows a typical small r-wave with a larger S-wave, while V6 demonstrates a dominant R-wave, indicating normal R-wave progression across the precordial leads. Technical parameters visible at the bottom of the strip indicate a standard sweep speed of 25.0 mm/s and a voltage calibration of 10.0 mm/mV. This ECG is presented as a reference for correct lead placement and normal electrical conduction after correcting previous technical errors.

This diagnostic image is a 12-lead electrocardiogram (ECG/EKG) displayed on a standard pink grid background. The tracing shows a regular rhythm with a heart rate of approximately 77 beats per minute. Key visual findings include narrow QRS complexes across both limb leads (I, II, III, aVR, aVL, aVF) and precordial leads (V1-V6). In the limb leads, distinct Q, R, and S waves are visible with no significant slurring or notching. T waves are upright in leads I, II, aVF, and V4-V6, while inverted in aVR. Precordial leads show normal R-wave progression from V1 to V6. The ECG represents a post-intervention state following the placement of a transvenous pacemaker (TVP) for a previous complete heart block and hyperkalemia. The current tracing demonstrates resolution of previous bradycardia and successful stabilization of the cardiac rhythm with improved QRS and T wave morphology.

This diagnostic image is a comparison chart of electrocardiography (ECG) tracings, displaying a side-by-side assessment of six leads (I, II, III, V1, V4, and V6). The left column shows standard 12-lead ECG recordings in black, while the right column shows corresponding single-lead ECGs captured by a smartwatch (Apple Watch) in red. The image demonstrates high morphological correlation between the two modalities across Einthoven limb leads (I-III) and Wilson-like chest leads (V1, V4, V6). Key visual features include visible P waves, sharp QRS complexes, and T waves in both sets. Notably, the smartwatch recordings (red) exhibit higher relative amplitudes and slightly more baseline wander compared to the standard ECG (black). In lead V1, both modalities show a predominant S-wave, reflecting correct precordial placement. This educational material serves to illustrate the clinical utility and signal quality of consumer-grade wearables in mimicking standard diagnostic leads for heart rhythm and waveform analysis.

This diagnostic image consists of two 12-lead electrocardiograms (ECG) labeled (a) and (b), illustrating the electrical manifestations of situs inversus totalis and comorbid coronary artery disease. Panel (a) shows an ECG with standard lead placement, demonstrating a negative P-wave in leads I and aVL and a positive P-wave in lead aVR, characteristic of dextrocardia. Panel (b) shows the ECG after correcting for situs inversus by reversing the right and left limb leads and placing chest leads in a mirror-image configuration on the right side of the thorax. This corrected view reveals underlying ischemic changes, specifically ST-segment depression in the lateral leads (I, aVL, V5, V6) and T-wave inversions in the inferior (II, III, aVF) and precordial (V4-V6) leads. These visual findings provide a clinical comparison between the baseline electrical axis abnormalities seen in situs inversus and the subsequent diagnosis of multi-vessel coronary artery disease through modified lead positioning.

A 12-lead electrocardiogram (ECG) recorded at a standard paper speed of 25 mm/sec and calibration of 10 mm/mV. The tracing demonstrates low QRS voltage throughout both the limb leads (I, II, III, aVR, aVL, aVF) and the precordial leads (V1–V6). In the precordial leads specifically, there is notable 'poor R wave progression' (PRWP), characterized by the failure of the R wave amplitude to increase appropriately from V1 through V4. Instead of the typical transition to a dominant R wave by lead V3 or V4, the R waves remain stunted and small across the chest leads. These findings are clinically significant as they can be associated with various conditions including prior anterior myocardial infarction, cardiomyopathy, pulmonary disease (e.g., COPD), or technical factors like obesity or improper lead placement. The rhythm appears to be sinus, and the baseline shows no significant ST-segment or T-wave abnormalities in this view.

This diagnostic image shows two comparative electrocardiogram (ECG) rhythm strips, labeled A and B, displayed on a standard grid background. Both strips demonstrate a regular sinus rhythm with clearly identifiable P waves, QRS complexes, and T waves. Sample A represents a baseline or 'sham' control group, showing stable R-R intervals and standard waveform morphology. Sample B represents an experimental group (traumatic brain injury model) used to evaluate autonomic and cardiac effects. While the basic sinus rhythm remains intact, Sample B demonstrates subtle variations in the cardiac cycle, specifically in the P-wave duration and P-R interval as noted in related clinical studies. The ST segments in both samples appear isoelectric with no evidence of significant elevation or depression, and the T waves show normal upward deflection. This comparison is used in medical education to illustrate how systemic injuries, such as diffuse traumatic brain injury, can influence cardiac electrical activity and conduction intervals despite the absence of gross structural heart damage.

A diagnostic image showing a multi-lead electrocardiogram (ECG) waveform display on a standard red grid background. The image presents two continuous traces labeled as 'MLII' (Modified Limb Lead II) and 'V5', which are common leads used for arrhythmia monitoring. The waveforms demonstrate regular R-R intervals and narrow QRS complexes, with visible P waves and T waves associated with each heartbeat. Below the waveforms, structured text annotations (including labels 'pu', 'pu0', and 'pu1') provide algorithmic beat-by-beat analysis and fiducial point markings, such as identified P and T wave peaks. Time stamps are visible along the x-axis, ranging from 00:00:00 to 00:00:10, indicating a 10-second recording segment. This visual material is used in medical education to demonstrate normal sinus rhythm versus rhythm disturbances (arrhythmias) and to illustrate digital ECG signal processing and annotation techniques found in clinical database software like PhysioNet.