V6 mein woh "X" (deep downward deflection) kahan se aaya?

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Step by step samjho - 3 vectors hain V6 ke liye

Vector 1 - Septal (Left → Right)

• Current V6 se door ja raha hai (V6 left side pe hai, current right ja raha)
• V6 mein small q (negative, neeche) - ye already samajh aa gaya tumhe ✓

Vector 2 - Main Ventricular (LV dominant, Left + Posterior)

• Current V6 ki taraf aa raha hai
• V6 mein tall R wave (positive, upar) - ye bhi samajh aa gaya ✓

Vector 3 - BASAL depolarization (yahi X ka source hai)

1. Pehle septum depolarize hota hai (left → right)
2. Phir main free wall / apex (left + posterior dominant)
3. Sabse end mein - basal portion of ventricles depolarize hota hai

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V1 mein S ke baad baseline pe kyun aa gaya?

• r (septal - V1 ki taraf) ✓
• S (main LV vector - V1 se door) ✓
• Basal vector thoda right oriented hai, matlab V1 ki taraf hai - but itna chota hota hai ki V1 pe ek negligible positive deflection hoti hai jo practically baseline jitni dikhti hai

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LVH mein X (S wave in V6) aur deep S in V1 kyun zyada pronounced?

• Vector 2 (main LV vector) bahut powerful ho jaata hai
• V1 mein ye vector door ja raha hai → deeper S in V1 (Sv1 increases)
• V6 mein ye vector aata hai → taller R in V6 (Rv6 increases)

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Summary ek line mein

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Best Book for This Topic

1. Ganong's Review of Medical Physiology (26th Edition)

"...there is a large R wave (septal and left ventricular depolarization) followed in V1 and V5 by a moderate S wave (late depolarization of the ventricular walls moving back toward the AV junction)"

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2. Harrison's Principles of Internal Medicine (22nd Ed, 2025)

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3. Goldman-Cecil Medicine

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Short Recommendation

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Ganong mein exact explanation - Line by Line

"The wave of excitation first moves across the midportion of the septum from left to right toward the exploring electrode (= small r in V1)"

"Then moves down the septum and into the left ventricle AWAY from the electrode (= large S in V1)"

"Finally, it moves BACK along the ventricular wall TOWARD the electrode - producing the return to isoelectric line in V1"

"...there is a large R wave (septal and left ventricular depolarization) followed in V5 and V6 by a moderate S wave (late depolarization of the ventricular walls moving back toward the AV junction)"

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Ye image dekho - Normal ECG from Ganong:

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To Seedha Answer

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ECG - Basic to Advanced (Harrison 22E)

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PART 1: Heart ka Electrical System - Pehle Ye Samjho

SA Node → Right Atrium → Left Atrium
              ↓
         AV Node (yahan delay hoti hai - atria ko contract karne ka time milta hai)
              ↓
         His Bundle
              ↓
    Left Bundle Branch + Right Bundle Branch
              ↓
         Purkinje Fibers (endocardium tak)
              ↓
    Ventricular muscle (endocardium → epicardium)

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PART 2: ECG Waves - Har Wave Ka Matlab

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PART 3: ECG Paper - Numbers Yaad Karo

1 small box (1mm)  = 0.04 seconds (40 ms)
1 large box (5mm)  = 0.20 seconds (200 ms)

Amplitude: 1 mV = 10 mm (standard calibration)

• 300 ÷ number of large boxes between 2 R waves
• Ya 1500 ÷ number of small boxes between 2 R waves

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PART 4: Normal Intervals (Yaad Karo - Exam Important)

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PART 5: 12 Leads - Kaun Sa Lead Kahan Dekhta Hai

• Lead I, II, III - bipolar
• aVR, aVL, aVF - augmented unipolar

• V1 se V6

Leads ka Geography (Kaunsa lead kaunsi wall dekhta hai):

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PART 6: P Wave - Normal aur Abnormal

• Lead II mein positive (current SA node se aV node ki taraf = Lead II ki taraf)
• aVR mein negative (current aVR se door)
• V1 mein biphasic hoti hai - pehle positive (RA), phir small negative (LA)

• Ectopic pacemaker agar lower atrium ya AV junction se ho → retrograde P waves (II mein negative, aVR mein positive)

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PART 7: QRS Complex - Ventricular Depolarization

• V1: small r (taraf aa raha)
• V6: small q (door ja raha)

• V1: deep S (door ja raha)
• V6: tall R (taraf aa raha)

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PART 8: ST Segment aur T Wave

• ST segment isoelectric (baseline pe) hona chahiye
• T wave normally QRS ke same direction mein hoti hai (concordant)
• Repolarization epicardium se endocardium ki taraf hoti hai (depolarization se ulta)

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PART 9: QRS Axis

• Lead I positive + Lead aVF positive = Normal axis
• Lead I positive + Lead aVF negative = Left axis deviation
• Lead I negative + Lead aVF positive = Right axis deviation

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PART 10: Chamber Enlargement

Left Atrial Enlargement (LAE):

• P wave V1 mein - terminal negative component >1 mm² (1mm wide + 1mm deep)
• P wave duration >120 ms in Lead II ("P mitrale" - bifid P)

Right Atrial Enlargement (RAE):

• P wave Lead II mein tall >2.5 mm ("P pulmonale")

Left Ventricular Hypertrophy (LVH) - Sokolow-Lyon Criteria:

Right Ventricular Hypertrophy (RVH):

• V1 mein dominant R wave (R > S in V1)
• Right axis deviation
• ST depression + T inversion in V1-V3

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PART 11: Bundle Branch Blocks

RBBB (Right Bundle Branch Block):

• QRS >120 ms
• V1 mein rSR' pattern ("rabbit ears" / M pattern)
• V6 mein qRS (wide S wave)
• T wave discordant in right leads

LBBB (Left Bundle Branch Block):

• QRS >120 ms
• V1 mein deep QS ya rS
• V6 mein broad, notched R wave (no septal q, no S)
• ST-T completely discordant

Hemiblocks:

• Left Anterior Fascicular Block (LAFB): Left axis deviation (<-45°), qR in I/aVL, rS in II/III/aVF, QRS <120 ms
• Left Posterior Fascicular Block (LPFB): Right axis deviation, rS in I/aVL, qR in III, rare

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PART 12: Ischemia aur MI

ST Changes:

• ST elevation (STEMI): Transmural ischemia/infarction - current of injury toward electrode
• ST depression: Subendocardial ischemia ya reciprocal changes

Q Waves:

• Pathological Q wave = >40 ms wide OR >1/4 of R wave height
• Represent necrotic (dead) myocardium - electrically silent area

MI Localization:

Evolutionary Changes (STEMI mein time ke saath):

Minutes: Hyperacute T waves (tall, peaked)
Hours:   ST elevation
Days:    Q waves form, ST normalizes, T inverts
Weeks:   T waves normalize (Q waves may persist)

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PART 13: Other Important ECG Patterns

Hyperkalemia:

• Early: Peaked (tall, narrow, symmetric) T waves
• Later: PR prolongation, QRS widening
• Severe: Sine wave pattern, VF/asystole

Hypokalemia:

• U waves prominent (may merge with T wave)
• Flat/inverted T waves
• QT prolongation (actually QU prolongation)

Hypercalcemia:

• Short QT interval

Hypocalcemia:

• Long QT interval (ST segment prolonged)

Digoxin effect:

• "Reverse tick" / "Salvador Dali moustache" ST pattern
• Scooped ST depression in lateral leads
• Short QT

Pericarditis:

• Diffuse ST elevation (saddle-shaped) in almost all leads
• PR depression (atrial injury)
• No reciprocal changes (unlike MI)

WPW (Wolff-Parkinson-White):

• Short PR interval (<120 ms)
• Delta wave (slurred QRS upstroke)
• Wide QRS
• SVT tendency

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Summary Table - Exam ke liye

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