{ "schema": "ekg-weighted-practice-methods/1", "date": "2026-10-29", "scope": "Original educational measurement notes, not clinical certification.", "scoring": { "case3": { "scale": "independent-weighted-practice-v1", "version": "2-code64-consistency", "weights": [ 1, 2, 2, 3, 2 ], "repolarizationAlternatives": [ 64, 67 ], "neutralRows": [ 6, 54, 68 ], "incorrectRows": 80, "maximum": 10 }, "case5": { "classificationsChanged": false, "weightsChanged": false, "maximum": 8 } }, "measurements": { "case3": { "binding": { "candidateId": "005b0ac5-c985-4dec-91ff-617e2b7e1f0f", "waveformSha256": "35049bad0e561f9c4cb138f3c965e10161d4d8659c5d6e796a02231cfb1e8a9c", "waveformVersion": "ptbxl-1.0.3:physical-mv-f64le-v1", "payloadSha256": "ec1a7216d23e5d23cd7618c53a72a7ea32086cbb55b95f4e0043551b33769415", "taxonomySha256": "49eb2acaff86b4e4482382d017b0f8761eeb84e57757a20e1445593c507fdd20" }, "visibleV6": { "panelSeconds": [ 7.5, 10 ], "nativeQrsOnsetSec": 9.14, "nativeRPeakSec": 9.176, "TtroughSec": 9.41, "TtroughSample": 4705, "TtroughmV": -0.45, "baselineEndpointConvention": "half-open: include the first sample, exclude the ending time", "preQrsBaselineSec": [ 9.11, 9.14 ], "preQrsBaselinemV": [ -0.157, -0.118 ], "preQrsMedianmV": -0.136, "subsequentTpSec": [ 9.55, 9.65 ], "subsequentTpBaselinemV": [ -0.129, -0.06 ], "subsequentTpMedianmV": -0.108, "inversionAgainstPreQrsBoundmV": [ 0.293, 0.332 ], "interpretation": "Native-shaped beat after a PVC. Post-extrasystolic timing limits causal inference, not descriptive threshold recognition." } }, "case5": { "binding": { "candidateId": "01584fb5-e504-4b5b-a42f-c75b38be6fb5", "waveformSha256": "0a20763cca23df4537ef40670ca4e8143211083d1aef020be2819b8dc2573e7c", "waveformVersion": "ptbxl-1.0.3:physical-mv-f64le-v1", "payloadSha256": "f8c07ef869ad7898b80860b56a372d80379a8eb5f764737b6a9a0291130f193f", "taxonomySha256": "49eb2acaff86b4e4482382d017b0f8761eeb84e57757a20e1445593c507fdd20" }, "visiblePR": { "atrialLead": "V1", "prePBaselineSec": [ 6.808, 6.836 ], "prePBaselinemV": 0.045, "observedAtrialRiseSec": [ 6.836, 6.84 ], "POnsetSec": [ 6.834, 6.84 ], "sameBeatQrsLeads": [ "V1", "II" ], "QrsOnsetSec": [ 7.042, 7.05 ], "conservativePRms": [ 202, 216 ], "nominalPRms": 210, "method": "Conservative visibly bounded interval. Small P onset supported by repeated atrial phase in displayed V2 and contemporaneous V3. Do not pair noncontemporaneous panel windows." }, "visibleQRS": [ { "onsetSec": [ 9.352, 9.36 ], "endSec": [ 9.45, 9.462 ], "durationMs": [ 90, 110 ] }, { "onsetSec": [ 5.518, 5.52 ], "endSec": [ 5.618, 5.628 ], "durationMs": [ 98, 110 ] } ], "visibleV4QT": { "onsetSec": [ 9.352, 9.36 ], "TendSec": [ 9.77, 9.778 ], "localBaselinemV": -0.2, "QTms": [ 410, 426 ], "precedingRRms": 768, "BazettQTcms": [ 468, 486 ] } } }, "reproduction": [ "Read the bound public waveform payload and confirm its full-byte SHA-256. Samples are physical mV; use the payload sample rate rather than estimating from image pixels.", "Default display is sequential 2.5-second panels plus the 10-second II strip. Use the stated lead/time window; do not join P and QRS endpoints from different beats.", "At 500 Hz, sample index = time in seconds × 500. Endpoint ranges express manual waveform uncertainty; exact sample values do not remove attribution uncertainty.", "For the V6 trough subtract −0.450 mV from each bound of the local baseline. Compute QTc = QT / square root of R-R in seconds; report endpoint intervals, not an unsupported precise multibeat mean.", "The downloadable reproduction module verifies payload pins and recalculates the V6 baseline/trough and interval arithmetic. It does not automatically diagnose findings." ], "rows": { "case3": [ { "row": 1, "optionId": "ecg-normal-ecg", "classification": "incorrect", "rationale": "Irregular atrial rhythm, frequent ventricular ectopy, high LV voltage and repolarization abnormalities preclude normal ECG.", "uncertainty": null }, { "row": 2, "optionId": "ecg-normal-variant", "classification": "incorrect", "rationale": "The rhythm and voltage/repolarization abnormalities are not an isolated normal variant.", "uncertainty": null }, { "row": 3, "optionId": "ecg-electrode-placement-error", "classification": "incorrect", "rationale": "Native QRS complexes are positive in I, predominantly negative in aVR, and show progressive precordial transition. No coherent lead-reversal pattern is established. The abrupt displacement near 8.1 s is artifact, not a stable new electrode-placement pattern.", "uncertainty": null }, { "row": 4, "optionId": "ecg-artifact", "classification": "required", "rationale": "The displayed II rhythm strip has a large abrupt baseline displacement near 8.1 s and persistent fine limb-lead noise. Native I, II, aVR and aVL corroborate shifts of approximately 1.4–1.6 mV; the artifact is already visible in the displayed II strip.", "uncertainty": null }, { "row": 5, "optionId": "ecg-right-atrial-abnormality", "classification": "incorrect", "rationale": "No clear atrial deflection exceeds 0.25 mV in II, III or aVF, or 0.15 mV for a positive component in V1 or V2, measured from its local baseline. Changing ectopic P morphology is not an amplitude criterion for right atrial abnormality.", "uncertainty": null }, { "row": 6, "optionId": "ecg-left-atrial-abnormality", "classification": "neutral", "rationale": "In displayed V1 near 5.07 s, overlapping P and preceding T activity reaches −0.030 mV against a plausible subsequent baseline of 0.060–0.100 mV over roughly 50–70 ms. The estimated negative depth of 0.09–0.13 mV straddles the terminal-negative P threshold, but overlap and premature atrial morphology prevent secure attribution. This choice is neutral, not proof of atrial enlargement.", "uncertainty": "P/T overlap and changing atrial morphology make terminal-P component attribution uncertain." }, { "row": 7, "optionId": "ecg-sinus-rhythm", "classification": "incorrect", "rationale": "Normal-axis sinus rhythm is not established. Early positive inferior atrial deflections are compatible with sinus activation, but lead-I P polarity is obscured by noise; later organized inferior P waves are negative. Organized atrial activity is present, so irregularity alone should not be called atrial fibrillation.", "uncertainty": null }, { "row": 8, "optionId": "ecg-sinus-arrhythmia", "classification": "incorrect", "rationale": "No coherent normal-axis sinus sequence with qualifying P-P variability greater than 10% or 0.16 s is established independently of the changing P morphology and ectopy. Irregular R-R intervals alone do not establish sinus arrhythmia.", "uncertainty": null }, { "row": 9, "optionId": "ecg-sinus-bradycardia", "classification": "incorrect", "rationale": "No normal-axis atrial sequence below60/min is established.", "uncertainty": null }, { "row": 10, "optionId": "ecg-sinus-tachycardia", "classification": "incorrect", "rationale": "An early positive-II P pair separated by approximately 536 ms gives an apparent atrial rate of 112/min, but normal upright I/II P axis is not established because lead I is noisy. Rate alone does not establish sinus tachycardia; no additional minimum-run rule is imposed.", "uncertainty": null }, { "row": 11, "optionId": "ecg-sinus-pause-arrest", "classification": "incorrect", "rationale": "No >2-second interval without atrial activity establishes sinus arrest.", "uncertainty": null }, { "row": 12, "optionId": "ecg-sinoatrial-exit-block", "classification": "incorrect", "rationale": "There is no demonstrated fixed sinus P-P cycle with a qualifying sinoatrial exit-block pause pattern.", "uncertainty": null }, { "row": 13, "optionId": "ecg-premature-atrial-complexes", "classification": "required", "rationale": "In the displayed II rhythm strip, a negative atrial trough near 4.638 s is followed by a changed positive P peak near 5.098 s and the next negative trough near 5.840 s: intervals of approximately 460 and 742 ms. The early changed P precedes a native-shaped QRS with onset approximately 5.198–5.206 s (II peak near 5.248 s). This supports a premature atrial complex without requiring a proven sinus background.", "uncertainty": null }, { "row": 14, "optionId": "ecg-atrial-tachycardia", "classification": "incorrect", "rationale": "No convincing succession of at least three rapid abnormal P waves is shown. Isolated premature atrial activity is established. A rate of 100–180/min is typical of atrial tachycardia, not an exhaustive mandatory range.", "uncertainty": null }, { "row": 15, "optionId": "ecg-multifocal-atrial-tachycardia", "classification": "incorrect", "rationale": "At least three distinct P morphologies together with an atrial rate above 100/min are not established. Changing or biphasic atrial morphology amid ectopy and artifact is insufficient.", "uncertainty": null }, { "row": 16, "optionId": "ecg-supraventricular-tachycardia", "classification": "incorrect", "rationale": "A regular supraventricular rhythm above 100/min is not established. Early R-R acceleration with uncertain atrial axis does not by itself establish supraventricular tachycardia.", "uncertainty": null }, { "row": 17, "optionId": "ecg-atrial-flutter", "classification": "incorrect", "rationale": "No regular sawtooth atrial sequence at 240-340/min is demonstrated in inferior leads or V1.", "uncertainty": null }, { "row": 18, "optionId": "ecg-atrial-fibrillation", "classification": "incorrect", "rationale": "Organized atrial deflections are reproducible in inferior and right-precordial leads. Irregularity and artifact alone do not establish atrial fibrillation.", "uncertainty": null }, { "row": 19, "optionId": "ecg-premature-junctional-complexes", "classification": "incorrect", "rationale": "The demonstrated premature native-shaped QRS has a preceding changed atrial deflection, rather than an independently established junctional ectopic mechanism.", "uncertainty": null }, { "row": 20, "optionId": "ecg-junctional-escape-complexes", "classification": "incorrect", "rationale": "No late isolated junctional escape complex is identified; broad complexes are premature rather than late.", "uncertainty": null }, { "row": 21, "optionId": "ecg-junctional-rhythm-tachycardia", "classification": "incorrect", "rationale": "No independently established junctional escape or regularly repeating junctional rhythm is shown. Negative inferior P waves can reflect ectopic atrial or retrograde activation, so a preceding P wave alone does not anatomically exclude a junctional origin.", "uncertainty": null }, { "row": 22, "optionId": "ecg-premature-ventricular-complexes", "classification": "required", "rationale": "Repeated broad premature complexes have similar morphology, with later coupling intervals approximately 376–408 ms. Dominant initial right-precordial R waves and broad negative V6 forces differ from the native complexes and favor monomorphic PVCs. Relative long-short timing alone does not establish aberrancy.", "uncertainty": null }, { "row": 23, "optionId": "ecg-ventricular-parasystole", "classification": "incorrect", "rationale": "No independently marching common interectopic period with demonstrably variable coupling is established. Similar isolated broad complexes are insufficient for ventricular parasystole.", "uncertainty": null }, { "row": 24, "optionId": "ecg-ventricular-tachycardia", "classification": "incorrect", "rationale": "No three consecutive ventricular ectopic complexes or sustained ventricular tachycardia occurs.", "uncertainty": null }, { "row": 25, "optionId": "ecg-accelerated-idioventricular-rhythm", "classification": "incorrect", "rationale": "No consecutive ventricular-origin rhythm in the accelerated escape range of approximately 60–110/min is shown. The broad premature complexes remain separated by native beats.", "uncertainty": null }, { "row": 26, "optionId": "ecg-ventricular-escape", "classification": "incorrect", "rationale": "The broad beats are premature, not a slow ventricular escape rhythm at 20-40/min.", "uncertainty": null }, { "row": 27, "optionId": "ecg-ventricular-fibrillation", "classification": "incorrect", "rationale": "Organized discrete QRS complexes persist throughout, without ventricular fibrillation.", "uncertainty": null }, { "row": 28, "optionId": "ecg-first-degree-av-block", "classification": "incorrect", "rationale": "Visible conducted P-to-QRS intervals are short to normal. The premature atrial P onset near 5.04 s to the displayed native QRS onset near 5.20 s is approximately 160 ms. No confidently qualifying conducted interval of at least 200 ms is established; no all-beats or mean-PR requirement is imposed.", "uncertainty": null }, { "row": 29, "optionId": "ecg-mobitz-one-av-block", "classification": "incorrect", "rationale": "No progressive PR-lengthening sequence culminating in a blocked organized P is demonstrated.", "uncertainty": null }, { "row": 30, "optionId": "ecg-mobitz-two-av-block", "classification": "incorrect", "rationale": "No fixed-PR conducted sequence with an unexpected nonconducted organized P is established.", "uncertainty": null }, { "row": 31, "optionId": "ecg-two-to-one-av-block", "classification": "incorrect", "rationale": "No repeated regular two-P-to-one-QRS relationship is demonstrated.", "uncertainty": null }, { "row": 32, "optionId": "ecg-third-degree-av-block", "classification": "incorrect", "rationale": "Organized atrial activity precedes native complexes, without an independent regular escape rhythm or demonstrated complete AV dissociation. Complete AV block is not supported.", "uncertainty": null }, { "row": 33, "optionId": "ecg-wpw-pattern", "classification": "incorrect", "rationale": "Native initial activation has no delta wave; no coherent short-PR-plus-preexcitation pattern is established.", "uncertainty": null }, { "row": 34, "optionId": "ecg-av-dissociation", "classification": "incorrect", "rationale": "Atrial activity is associated with native complexes; no independent atrial and ventricular rhythms with the specified rate relationship establish AV dissociation.", "uncertainty": null }, { "row": 35, "optionId": "ecg-low-limb-voltage", "classification": "incorrect", "rationale": "Native II/III/aVF QRS amplitude is approximately 0.8-1.0 mV and exceeds the all-limb 0.5 mV limit.", "uncertainty": null }, { "row": 36, "optionId": "ecg-low-precordial-voltage", "classification": "incorrect", "rationale": "Native V2-V6 voltages substantially exceed 1 mV; the all-precordial low-voltage criterion fails.", "uncertainty": null }, { "row": 37, "optionId": "ecg-left-axis-deviation", "classification": "incorrect", "rationale": "Native I and II/aVF are positive overall, not a left-superior axis pattern.", "uncertainty": null }, { "row": 38, "optionId": "ecg-right-axis-deviation", "classification": "incorrect", "rationale": "Native I has net positive QRS with positive inferior forces; no right-axis range is established. Ectopic axis is not substituted for native axis.", "uncertainty": null }, { "row": 39, "optionId": "ecg-electrical-alternans", "classification": "incorrect", "rationale": "Morphology changes correspond to a distinct premature ventricular beat type and baseline artifact, not electrical alternans of otherwise comparable beats.", "uncertainty": null }, { "row": 40, "optionId": "ecg-left-ventricular-hypertrophy", "classification": "required", "rationale": "Visible native aVL R at 3.570 s is 0.347 mV above the signal origin, with local baseline 0.025–0.106 mV: R amplitude 0.241–0.322 mV. V3 S at 5.246 s is −3.446 mV with baseline 0.228–0.271 mV: S depth 3.674–3.717 mV. The Cornell sum is 3.915–4.039 mV, above both female 2.0 mV and male 2.8 mV thresholds. These are different explicitly identified sequential beats; native same-beat data corroborate the voltage finding.", "uncertainty": null }, { "row": 41, "optionId": "ecg-right-ventricular-hypertrophy", "classification": "incorrect", "rationale": "Native V1 is predominantly negative without right-axis deviation. The dominant V1 R occurs in premature ventricular beats and is not native RVH evidence.", "uncertainty": null }, { "row": 42, "optionId": "ecg-combined-ventricular-hypertrophy", "classification": "incorrect", "rationale": "Left ventricular hypertrophy is supported, but neither right ventricular hypertrophy nor a combined-hypertrophy criterion is established.", "uncertainty": null }, { "row": 43, "optionId": "ecg-complete-rbbb", "classification": "incorrect", "rationale": "Native conducted QRS duration is approximately 100–108 ms without terminal R-prime morphology. Broad premature ventricular complexes do not establish complete right bundle branch block in the native rhythm.", "uncertainty": null }, { "row": 44, "optionId": "ecg-incomplete-rbbb", "classification": "incorrect", "rationale": "Native V1 and V2 lack the terminal R-prime pattern of right bundle branch block. Duration alone cannot establish incomplete right bundle branch block.", "uncertainty": null }, { "row": 45, "optionId": "ecg-left-anterior-fascicular-block", "classification": "incorrect", "rationale": "Native inferior forces are positive without the left-superior axis and inferior rS pattern.", "uncertainty": null }, { "row": 46, "optionId": "ecg-left-posterior-fascicular-block", "classification": "incorrect", "rationale": "Native I remains positive, and a rightward axis with rS I/aVL is not established.", "uncertainty": null }, { "row": 47, "optionId": "ecg-complete-lbbb", "classification": "incorrect", "rationale": "Native QRS duration is below 120 ms, without a coherent broad notched lateral R or delayed lateral R peak. Broad ectopic complexes are not evidence of baseline left bundle branch block.", "uncertainty": null }, { "row": 48, "optionId": "ecg-incomplete-lbbb", "classification": "incorrect", "rationale": "The native lateral morphology and marked terminal S in V4 and V5 do not establish an incomplete left bundle branch block pattern.", "uncertainty": null }, { "row": 49, "optionId": "ecg-aberrant-conduction", "classification": "incorrect", "rationale": "Broad premature complexes have distinct initial ventricular-type forces and short coupling, rather than a proven rate-dependent change of conducted native morphology. Relative long-short timing alone is insufficient to establish aberrant conduction.", "uncertainty": null }, { "row": 50, "optionId": "ecg-nonspecific-intraventricular-conduction", "classification": "incorrect", "rationale": "On inspected native complexes, the rapid terminal QRS-to-ST transition gives approximately 100–108 ms. This does not establish the mean QRS duration above 110 ms used for nonspecific intraventricular conduction delay. Counting gradual shallow ST recovery as QRS would overestimate duration.", "uncertainty": null }, { "row": 51, "optionId": "ecg-mi-anterolateral-recent-probably-acute", "classification": "incorrect", "rationale": "No contiguous anterolateral primary injury pattern is established. Anterior ST elevation is discordant to very deep negative QRS forces and accompanies LVH voltage.", "uncertainty": null }, { "row": 52, "optionId": "ecg-mi-anterolateral-indeterminate-probably-old", "classification": "incorrect", "rationale": "No contiguous pathological initial Q or QS pattern is established in V3–V6; native complexes retain initial positive forces.", "uncertainty": null }, { "row": 53, "optionId": "ecg-mi-anterior-anteroseptal-recent-probably-acute", "classification": "incorrect", "rationale": "Anterior ST elevation follows deep negative native complexes. No distinct primary anterior injury pattern is established independently of high-voltage discordance; ectopic repolarization and artifact are not used as injury measurements. This does not clinically exclude acute coronary disease.", "uncertainty": null }, { "row": 54, "optionId": "ecg-mi-anterior-anteroseptal-indeterminate-probably-old", "classification": "neutral", "rationale": "Displayed V1 and V2 are QS, but V3 retains a robust initial R near 5.214 s: 0.838 mV with local baseline 0.228–0.271 mV, giving an R amplitude of 0.567–0.610 mV. Marked LVH and this transition make an old anterior scar-pattern attribution uncertain. This choice is neutral rather than a required old-MI diagnosis; no universal minimum-lead rule is inferred.", "uncertainty": "LVH-associated QS morphology and preserved V3 initial R do not securely distinguish scar attribution." }, { "row": 55, "optionId": "ecg-mi-lateral-recent-probably-acute", "classification": "incorrect", "rationale": "No contiguous primary I/aVL ST elevation meets acute lateral injury criteria.", "uncertainty": null }, { "row": 56, "optionId": "ecg-mi-lateral-indeterminate-probably-old", "classification": "incorrect", "rationale": "Native I/aVL begin with positive forces, not a coherent pathological initial-Q pattern.", "uncertainty": null }, { "row": 57, "optionId": "ecg-mi-inferior-recent-probably-acute", "classification": "incorrect", "rationale": "Inferior ST segments do not show a coherent primary contiguous injury elevation. Negative inferior ectopic complexes are not native infarct evidence.", "uncertainty": null }, { "row": 58, "optionId": "ecg-mi-inferior-indeterminate-probably-old", "classification": "incorrect", "rationale": "Native II and aVF do not show qualifying initial Q waves at least 30 ms wide and 0.1 mV deep in at least two inferior leads. A small or variable initial negative deflection in III alone is insufficient.", "uncertainty": null }, { "row": 59, "optionId": "ecg-mi-posterior-recent-probably-acute", "classification": "incorrect", "rationale": "Native V1/V2 are predominantly negative, not the tall broad R plus concordant upright T posterior-infarct pattern.", "uncertainty": null }, { "row": 60, "optionId": "ecg-mi-posterior-indeterminate-probably-old", "classification": "incorrect", "rationale": "Native V1/V2 lack dominant R waves; the tall R in ectopic complexes is not posterior scar evidence.", "uncertainty": null }, { "row": 61, "optionId": "ecg-early-repolarization", "classification": "incorrect", "rationale": "Discordant anterior elevation accompanies marked LVH voltage, without a convincing normal-variant terminal R notch/slur pattern; ectopic repolarization is excluded.", "uncertainty": null }, { "row": 62, "optionId": "ecg-juvenile-t-wave-variant", "classification": "incorrect", "rationale": "No juvenile anterior T-inversion pattern is established. Adult age is corroborative context, not the sole basis for the ECG finding.", "uncertainty": null }, { "row": 63, "optionId": "ecg-nonspecific-st-t-changes", "classification": "incorrect", "rationale": "The main regional repolarization pattern accompanies high-voltage discordance. Mild local deviations are not denied, but a separate nonspecific ST/T objective is not added to the same established repolarization finding.", "uncertainty": null }, { "row": 64, "optionId": "ecg-ischemic-st-t-changes", "classification": "required", "rationale": "In the displayed V6 panel, the native-shaped QRS near 9.18 s is followed by a T trough at 9.410 s of −0.450 mV. Against the local pre-QRS baseline of −0.157 to −0.118 mV, inversion is 0.293–0.332 mV, exceeding the descriptive 0.2 mV inversion threshold. A subsequent TP baseline also leaves inversion above threshold. High voltage and post-extrasystolic timing affect causal attribution, not the visible inversion. This description or the hypertrophy-associated description earns the same one repolarization objective; neither establishes coronary causation.", "uncertainty": "Morphology qualifies descriptively; the tracing does not establish coronary causation." }, { "row": 65, "optionId": "ecg-injury-st-t-changes", "classification": "incorrect", "rationale": "No distinct primary acute-injury pattern is established beyond the secondary QRS-discordant changes. Artifact and ectopic repolarization are not substituted for a separate injury pattern.", "uncertainty": null }, { "row": 66, "optionId": "ecg-electrolyte-st-t-changes", "classification": "incorrect", "rationale": "The T waves are not diffusely narrow-peaked, and there is no characteristic prominent-U/flattened-T combination. The regional repolarization pattern follows LVH voltage rather than a specific electrolyte pattern.", "uncertainty": null }, { "row": 67, "optionId": "ecg-hypertrophy-st-t-changes", "classification": "required", "rationale": "Deep negative native V2/V3 complexes have positive discordant ST/T forces, while a positive native V6 complex has negative ST/T. Together with high Cornell voltage, this supports a hypertrophy-associated repolarization pattern. The qualifying V6 inversion also permits the descriptive ischemic-ST/T option for the same objective; selecting both earns only the shared weight of 2. The ECG does not establish a unique coronary or noncoronary cause.", "uncertainty": "A hypertrophy-associated pattern is supported, but the tracing does not establish an exclusive cause." }, { "row": 68, "optionId": "ecg-prolonged-qt", "classification": "neutral", "rationale": "On the displayed short-cycle premature atrial beat, V3 QRS onset is approximately 5.198–5.204 s. A tangent T endpoint near 5.519–5.520 s gives QT 315–322 ms and Bazett QTc approximately 448–458 ms at R-R 494 ms; return to local baseline near 5.526–5.532 s gives QT 322–334 ms and QTc approximately 458–475 ms. Variable R-R intervals, ectopy and a tapering endpoint straddle the female threshold above 460 ms. This choice is neutral because the endpoint-dependent inference is uncertain, not because a mean or all-beats rule is required.", "uncertainty": "T-end method, variable R-R interval and ectopy straddle the corrected-QT threshold." }, { "row": 69, "optionId": "ecg-prominent-u-waves", "classification": "incorrect", "rationale": "No reproducible separate U wave greater than 0.15 mV is established; the broad anterior positive waveform is the T wave.", "uncertainty": null }, { "row": 70, "optionId": "ecg-brugada-syndrome", "classification": "incorrect", "rationale": "No coved or saddleback right-precordial ST morphology with the required pseudo-RBBB pattern is present.", "uncertainty": null }, { "row": 71, "optionId": "ecg-digitalis-toxicity", "classification": "incorrect", "rationale": "No characteristic digitalis-toxicity arrhythmia pattern is established. Medication exposure or toxicity cannot be inferred or clinically excluded from ectopy alone.", "uncertainty": null }, { "row": 72, "optionId": "ecg-torsades-de-pointes", "classification": "incorrect", "rationale": "No twisting polymorphic ventricular tachycardia is shown; broad premature beats have similar morphology and are separated by native beats.", "uncertainty": null }, { "row": 73, "optionId": "ecg-hyperkalemia", "classification": "incorrect", "rationale": "No diffuse narrow tented T pattern with generalized progressive native-QRS widening is established. This is an ECG-pattern assessment, not a laboratory potassium exclusion.", "uncertainty": null }, { "row": 74, "optionId": "ecg-hypokalemia", "classification": "incorrect", "rationale": "No prominent U waves with flattened T waves establish a hypokalemic pattern. Lateral depression alone with LVH is insufficient.", "uncertainty": null }, { "row": 75, "optionId": "ecg-hypercalcemia", "classification": "incorrect", "rationale": "Native QT is not conspicuously shortened. No hypercalcemic ECG pattern is established; serum calcium cannot be excluded by this tracing.", "uncertainty": null }, { "row": 76, "optionId": "ecg-hypocalcemia", "classification": "incorrect", "rationale": "No specific diffuse long-ST hypocalcemic pattern is established. Endpoint-dependent QT uncertainty does not assign an electrolyte cause.", "uncertainty": null }, { "row": 77, "optionId": "ecg-mirror-image-dextrocardia", "classification": "incorrect", "rationale": "Native I is positive and R amplitude increases into the left precordial leads, not mirror-image dextrocardia.", "uncertainty": null }, { "row": 78, "optionId": "ecg-acute-cor-pulmonale", "classification": "incorrect", "rationale": "No convincing native right-strain constellation, right axis, right bundle branch block or S1Q3T3 pattern is established. This does not clinically exclude pulmonary embolism.", "uncertainty": null }, { "row": 79, "optionId": "ecg-pericardial-effusion", "classification": "incorrect", "rationale": "High precordial voltage and the absence of true electrical alternans do not support a characteristic effusion pattern. This does not exclude an effusion anatomically.", "uncertainty": null }, { "row": 80, "optionId": "ecg-acute-pericarditis", "classification": "incorrect", "rationale": "No diffuse primary ST elevation with a coherent PR-depression/aVR PR-elevation pattern is established. Regional QRS-discordant repolarization accompanies LVH voltage instead.", "uncertainty": null }, { "row": 81, "optionId": "ecg-hypertrophic-cardiomyopathy", "classification": "incorrect", "rationale": "LVH voltage alone does not establish hypertrophic cardiomyopathy, and no distinctive additional HCM pattern is demonstrated. An etiologic diagnosis is not assigned.", "uncertainty": null }, { "row": 82, "optionId": "ecg-central-nervous-system-disorder", "classification": "incorrect", "rationale": "No distinct giant cerebral-type T wave and prominent-U constellation is established. No clinical neurologic diagnosis is inferred.", "uncertainty": null }, { "row": 83, "optionId": "ecg-hypothermia", "classification": "incorrect", "rationale": "No reproducible J/Osborn waves or generalized hypothermic conduction pattern is demonstrated.", "uncertainty": null }, { "row": 84, "optionId": "ecg-atrial-coronary-sinus-pacing", "classification": "incorrect", "rationale": "No reproducible atrial pacing stimulus followed by atrial depolarization is visible.", "uncertainty": null }, { "row": 85, "optionId": "ecg-normal-vvi-pacing", "classification": "incorrect", "rationale": "No pacing stimulus or demand timing mechanism is established. The repeated broad beats occur prematurely and support ventricular ectopy rather than VVI demand pacing.", "uncertainty": null }, { "row": 86, "optionId": "ecg-normal-ddd-pacing", "classification": "incorrect", "rationale": "No atrial and ventricular stimulus sequence or AV-tracking pacing pattern is present.", "uncertainty": null }, { "row": 87, "optionId": "ecg-pacing-capture-failure", "classification": "incorrect", "rationale": "No pacing stimulus without an expected capture response is demonstrated.", "uncertainty": null }, { "row": 88, "optionId": "ecg-pacing-sensing-failure", "classification": "incorrect", "rationale": "No definite pacing stimulus at an inappropriate sensing interval is demonstrated.", "uncertainty": null }, { "row": 89, "optionId": "ecg-biventricular-paced-morphology", "classification": "incorrect", "rationale": "No demonstrated paced sequence or dual ventricular stimuli are present. An ectopic right-bundle-like morphology does not establish biventricular pacing.", "uncertainty": null } ], "case5Corrections": [ { "row": 28, "optionId": "ecg-first-degree-av-block", "rationale": "In the third displayed V1 beat, a flat pre-P baseline near 0.045 mV from 6.808–6.836 s is followed by an early atrial rise at 6.836–6.840 s and a sustained plateau into the main P wave. Allowing for low-amplitude onset uncertainty gives conservative P-onset bounds of 6.834–6.840 s. The same-beat V1/II ventricular onset is approximately 7.042–7.050 s. These visible calipers give a conservative PR interval of 202–216 ms (nominally 210 ms), meeting the inclusive threshold of at least 200 ms. Recurrent early atrial steps in displayed V2 and contemporaneous V3 ramps support the small early P component. A later, larger P in another lead does not erase the earlier atrial onset. The isolated V1 step near 6.988 s is not used as QRS onset because it is separated by a plateau and lacks a coherent simultaneous V2/II ventricular departure. Low amplitude limits precision; this is a qualifying-conducted-beat finding, not a mean-PR or all-beats rule." }, { "row": 40, "optionId": "ecg-left-ventricular-hypertrophy", "rationale": "Displayed local-baseline measurements give aVL R approximately 0.618 mV plus V3 S approximately 1.170 mV: Cornell voltage about 1.788 mV, below the male 2.8 mV threshold. V1 S approximately 0.804 mV plus V5 R approximately 1.884 mV gives about 2.688 mV, below 3.5 mV; aVL R is also below 1.1 mV. No LVH voltage criterion is established. These approximate amplitudes depend on the stated local baselines." }, { "row": 43, "optionId": "ecg-complete-rbbb", "rationale": "There is no terminal R-prime morphology or broad lateral terminal S pattern of right bundle branch block. Visible rapid-QRS intervals are approximately 90–110 ms, not a complete RBBB morphology-and-duration combination." }, { "row": 50, "optionId": "ecg-nonspecific-intraventricular-conduction", "rationale": "Visible late-beat QRS onset near 9.352–9.360 s and rapid QRS-to-ST transition near 9.450–9.462 s give a bounded duration of 90–110 ms. An earlier visible interval from 5.518–5.520 s to approximately 5.618–5.628 s gives 98–110 ms. These measurements do not establish mean QRS duration above 110 ms. They are bounded individual-beat measurements, not a claimed precisely measured multibeat mean." }, { "row": 68, "optionId": "ecg-prolonged-qt", "rationale": "In the fully visible final V4 beat, Q onset at 9.352–9.360 s and T return at 9.770–9.778 s to a matching local baseline near −0.200 mV give QT 410–426 ms. With preceding R-R 768 ms, Bazett QTc is approximately 468–486 ms, above the male threshold of 450 ms even at the lower bound. The low-amplitude, noisy endpoint limits precision, but the qualifying interval is visible in the displayed panel." }, { "row": 36, "optionId": "ecg-low-precordial-voltage", "rationale": "The displayed V4 beat near 9.394 s has QRS peak-to-peak amplitude 2.698 mV (minimum −1.020 mV and maximum 1.678 mV in the 9.35–9.47 s window). This exceeds 1.0 mV, so the all-precordial low-voltage criterion is not met." }, { "row": 53, "optionId": "ecg-mi-anterior-anteroseptal-recent-probably-acute", "rationale": "Initial positive deflections in V1 and V2 and a preserved V3 R are present. No qualifying contiguous anterior acute-injury ST-elevation pattern is established." } ] }, "sourcePointers": { "bibliography": "ECGsource ECG interpretation teaching cases, compiled reference anthology. References below identify source-case trace and answer pages, not website recording numbers. No source images or answer text are reproduced.", "weightAssurance": "These are interpretive comparators, not the identity of these recordings or an official weight table. Practice weights are editorial.", "pairs": [ { "sourceCase": 42, "tracePage": 2240, "answerPage": 2241, "comparison": "LVH with descriptive ischemic ST/T credit; similar QS transition without old-anterior-MI credit." }, { "sourceCase": 48, "tracePage": 694, "answerPage": 695, "comparison": "Descriptive ST depression or T-inversion threshold." }, { "sourceCase": 22, "tracePage": 157, "answerPage": 158, "comparison": "LVH with secondary hypertrophy-associated ST/T changes." }, { "sourceCase": 68, "tracePage": 323, "answerPage": 324, "comparison": "Positive anterior scar-pattern comparison." }, { "sourceCase": 86, "tracePage": 333, "answerPage": 334, "comparison": "Positive anterior scar-pattern comparison." }, { "sourceCase": 332, "tracePage": 1084, "answerPage": 1085, "comparison": "Positive anterior scar-pattern comparison and inclusive first-degree AV-block criterion." }, { "sourceCase": 170, "tracePage": 160, "answerPage": 161, "comparison": "Artifact, sinus rhythm, nonspecific ST/T and prolonged QT co-coding." } ] } }