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PQ Segment

PR (PQ) segment

PQ Segment (PR Segment)

PR (PQ) segment is the isoelectric segment between the end of the P wave and the start of the QRS complex
  • Interval is a section that contains waves or oscillations
  • Segment is a section that contains only the isoelectric line
  • PQ Segment
    • It is the section between the end of the P wave and the beginning of the QRS complex
    • The QRS complex usually starts with the Q wave
  • PR Segment
    • Sometimes the PQ segment is referred to as the PR segment
      • When the QRS complex starts with the R wave
  • Regardless of the configuration of the QRS complex
    • The term "PQ Segment" is more commonly used
  • Rarely, the PQ segment is referred to as:
    • PTa Segment (where the Ta wave is atrial repolarization)
    • PTp Segment (Tp is "T wave of P wave", which is the Ta wave)
      • The Ta wave is not visible on the ECG; it is hidden within the QRS complex
  • PQ Segment has 4 possible designations
    • PQ, PR, PTa, PTp Segment
    • The most commonly used term is: PQ Segment

ECG Curve of the PQ Interval

SA node atrial activation and PQ (PR) segment
PQ (PR) segment and AV node (junction) conduction delayed
  1. Impulse originates in the SA node
    • When it passes to the atrial myocardium, it starts to create the P wave
    • Simultaneously, it spreads through the conduction system towards the AV node
      • The impulse in the conduction system does not create a curve
  2. The impulse enters the AV node
    • The impulse spreads from the SA node
      • through the myocardium (creating the P wave)
      • and through the conduction system (via the internodal pathways) into the AV node
    • At the time of atrial activation (peak of the P wave)
      • It arrives via the conduction system into the AV node
  3. Delayed (decremental) conduction in the AV node
    • The impulse pauses in the AV node for about 0.1s (no curve is formed)
    • Then it moves to the His bundle (no curve is formed)
  4. Activation of the interventricular septum
    • From the His bundle the impulse spreads through the Purkinje fibers
      • It starts to activate the myocardium of the interventricular septum
      • A Q wave begins to form

ECG and PQ Segment

ECG PQ (PR) normal segment 0.04 - 0.12s

Pericarditis



ECG acute pericarditis, PQ (PR) segment depression, concave ST elevation, TP (T-P) segment

ST Elevations and PQ Depressions



ECG acute pericarditis, PQ (PR) segment elevation aVR, reciprocal ST depression, TP (T-P) segment

ST Depressions and PQ Elevations




ECG acute pericarditis. Spodick sign, PR segment depression, Concave ST elevation, Reciprocal ST depression and PR elevation (aVR, V1)

Acute Pericarditis



ECG acute pericarditis. PQ segment depression, Concave ST elevation, Reciprocal ST depression and PQ elevation (aVR, V1)

Acute Pericarditis


Atrial Infarction

  • The atrial myocardium is thin
    • Therefore, ECG changes in atrial infarction (ischemia) are minimal
    • PQ elevations and PQ depressions occur
    • Changes persist for about 4 hours after infarction
    • According to ECG, ischemia cannot be differentiated from atrial infarction

Atrial ischemia (infarction) PR elevation, PR depression. Liu criteria
  • ECG and atrial infarction:
    • PQ elevation > 0.5mm (V5, V6) and reciprocal PQ depression (V1, V2)
    • PQ elevation > 0.5mm (I) and reciprocal PQ depression (II, III)
    • PQ depression > 1.5mm in precordial leads (V1-V6)
    • PQ depression > 1.2mm (I, II, III) and supraventricular arrhythmia
    • PQ depression > 1.2mm (II, III, aVF) and PQ elevation (aVR, V1)


ECG inferior STEMI and atrial ischaemia (infarction). PR elevation (aVR, V1), PR depression (II, III, aVF)

Atrial Infarction and Inferior Wall STEMI




Sources

  • ECG from Basics to Essentials Step by Step
  • litfl.com
  • ecgwaves.com
  • metealpaslan.com
  • medmastery.com
  • uptodate.com
  • ecgpedia.org
  • wikipedia.org
  • Strong Medicine
  • Understanding Pacemakers





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Home /

PQ Segment

PR (PQ) segment

PQ Segment (PR Segment)

  • Interval is a section that contains waves or oscillations
  • Segment is a section that contains only the isoelectric line
  • PQ Segment
    • It is the section between the end of the P wave and the beginning of the QRS complex
    • The QRS complex usually starts with the Q wave
  • PR Segment
    • Sometimes the PQ segment is referred to as the PR segment
      • When the QRS complex starts with the R wave
  • Regardless of the configuration of the QRS complex
    • The term "PQ Segment" is more commonly used
  • Rarely, the PQ segment is referred to as:
    • PTa Segment (where the Ta wave is atrial repolarization)
    • PTp Segment (Tp is "T wave of P wave", which is the Ta wave)
      • The Ta wave is not visible on the ECG; it is hidden within the QRS complex
  • PQ Segment has 4 possible designations
    • PQ, PR, PTa, PTp Segment
    • The most commonly used term is: PQ Segment


PR (PQ) segment is the isoelectric segment between the end of the P wave and the start of the QRS complex

ECG Curve of the PQ Interval

  1. Impulse originates in the SA node
    • When it passes to the atrial myocardium, it starts to create the P wave
    • Simultaneously, it spreads through the conduction system towards the AV node
      • The impulse in the conduction system does not create a curve
  2. The impulse enters the AV node
    • The impulse spreads from the SA node
      • through the myocardium (creating the P wave)
      • and through the conduction system (via the internodal pathways) into the AV node
    • At the time of atrial activation (peak of the P wave)
      • It arrives via the conduction system into the AV node
  3. Delayed (decremental) conduction in the AV node
    • The impulse pauses in the AV node for about 0.1s (no curve is formed)
    • Then it moves to the His bundle (no curve is formed)
  4. Activation of the interventricular septum
    • From the His bundle the impulse spreads through the Purkinje fibers
      • It starts to activate the myocardium of the interventricular septum
      • A Q wave begins to form
 SA node atrial activation and PQ (PR) segment


PQ (PR) segment and AV node (junction) conduction delayed

ECG and PQ Segment
ECG PQ (PR) normal segment 0.04 - 0.12s

Pericarditis


ECG acute pericarditis, PQ (PR) segment depression, concave ST elevation, TP (T-P) segment

ST Elevations and PQ Depressions

  • In all leads
  • Except aVR and V1
 ECG acute pericarditis, PQ (PR) segment elevation aVR, reciprocal ST depression, TP (T-P) segment

ST Depressions and PQ Elevations

  • Only in aVR and V1


ECG acute pericarditis. Spodick sign, PR segment depression, Concave ST elevation, Reciprocal ST depression and PR elevation (aVR, V1)

Acute Pericarditis



ECG acute pericarditis. PQ segment depression, Concave ST elevation, Reciprocal ST depression and PQ elevation (aVR, V1)

Acute Pericarditis


Atrial Infarction

  • The atrial myocardium is thin
    • Therefore, ECG changes in atrial infarction (ischemia) are minimal
    • PQ elevations and PQ depressions occur
    • Changes persist for about 4 hours after infarction
    • According to ECG, ischemia cannot be differentiated from atrial infarction

  • ECG and atrial infarction:
    • PQ elevation > 0.5mm (V5, V6) and reciprocal PQ depression (V1, V2)
    • PQ elevation > 0.5mm (I) and reciprocal PQ depression (II, III)
    • PQ depression > 1.5mm in precordial leads (V1-V6)
    • PQ depression > 1.2mm (I, II, III) and supraventricular arrhythmia
    • PQ depression > 1.2mm (II, III, aVF) and PQ elevation (aVR, V1)
 Atrial ischemia (infarction) PR elevation, PR depression. Liu criteria


ECG inferior STEMI and atrial ischaemia (infarction). PR elevation (aVR, V1), PR depression (II, III, aVF)

Atrial Infarction and Inferior Wall STEMI




Sources

  • ECG from Basics to Essentials Step by Step
  • litfl.com
  • ecgwaves.com
  • metealpaslan.com
  • medmastery.com
  • uptodate.com
  • ecgpedia.org
  • wikipedia.org
  • Strong Medicine
  • Understanding Pacemakers