Clinical Exercise Testing end of trimester exam
Sinus (exit) block - correct answer - Failure of sinus impulse to propagate through the atria.
- cannot distinguish between sinus block and sinus arrest.
- ECG: missed beat or abnormally long PR interval
What makes up the AV junction? - correct answer Av node and Bundle of HIS
1st Degree AV block - correct answer PR interval >0.20s
- Increased inherent refractoriness of tissue or tissue degeneration
- More prevalent in athletes (6-33%) than general pop (<1%).
2nd Degree AV block - Mobitz type 1 - correct answer Wenckebach pattern: AV conduction
progressively impaired until failure - almost always in AV node.
- Asymptomatic unless ventricular rate is very slow.
- Transient and benign
2nd Degree AV block - Mobitz type 2 - correct answer Intermittent, sudden interruption to AV
conduction - usually below AV node.
- PR interval normal, but then missed QRS complex (beat)
- "Missed beat" can be regular or variable.
- P wave to P wave rhythm is normal
Which 2nd degree AV block is associated with disease? - correct answer Mobitz Type 2. Can
progress to type 3 AV block.
3rd degree AV block - correct answer - complete heart block
- No transmission of stimuli from atria to ventricles
- Atria & ventricles paced independently (AV dissociation)
- p waves are regular and faster than the QRS complexes (wide and aberrant)
- serious and potentially life-threatening
- stroke's adams attacks
Stroke's-Adams Attacks - correct answer fainting spells associated with complete heart block
,All bundle branch blocks are? - correct answer - usually distinct from any problem with AV
conduction
- Wide QRS complex >0.12s (highly variable pattern)
RBBB - correct answer - Delayed conduction through the right ventricle.
- V1 Rsr' (rabbit ears)
- V6 QRS complex (emphasis on S wave)
- ST depression & T wave inversions (V1-V3) also common (considered secondary changes)
- Benign or heart disease (e.g. pulmonary hypertension, degenerative disease of conduction
system)
How to tell if RBBB or LBBB is complete or incomplete? - correct answer - Complete: QRS>0.12s
- Incomplete QRS<0.12s
LBBB - correct answer - Delayed conduction through the left ventricle.
- Reversal of septal depolarisation (right to left)
- Loss of normal septal r wave in V1 and q wave in V6.
- V5-V6 (wide QRS - broad and notched)
- Secondary ST depression & T wave inversions in leads with tall R waves (left lateral).
Who gets RBBB and LBBB? - correct answer RBBB: disease but also common in normal hearts
LBBB: rare in healthy hearts
BBB precludes diagnosis of hypertrophy (voltage criteria)
Hemiblocks - correct answer • Block in one or more fascicles of the LBB.
• Characteristics: alteration of QRS axis with normal QRS duration.
- Left Anterior Hemiblock: Left axis deviation (> -45˚)
- Left Posterior Hemiblock: Right axis deviation (> 120˚)
• Only if other causes of RVH excluded
Bifascicular block - correct answer - Impaired conduction down 2 of 3 main fascicles.
Trifascicular block. - correct answer - Impaired conduction down all 3 fascicles.
Bifascicular Blocks examples - correct answer 1.
,RBBB + LAH:
a) QRS>0.12 s & RSr' in V1 and V2 (RBBB)
b) Left axis deviation (LAH)
RBBB + LPH
a) RBBB - QRS>0.12 s & RSr' in V1 and V2 (RBBB)
b) Right axis deviation (LPH)
Pacemakers - correct answer Indicated when the heart is not capable of sustaining an intrinsic
rhythm & the patient is symptomatic.
• usage increased
• Delivers an electrical current that triggers depolarisation.
- Demand pacemakers
• Placed in atria or ventricles alone OR both (A-V sequential).
What conditions do pacemakers usually treat/manage? - correct answer - 2nd degree AV block
type 2
- 3rd degree AV block
- AV block/bradycardia with symptoms
- AV block + BBB during acute MI
- Recurrent brady or tachy-arrhythmias
- Sinus node dysfunction (sick sinus syndrome)
Myocardial Ischaemia - correct answer Restriction of O2 and nutrients to regions of the
myocardium.
- Restriction of blood flow through one or more coronary arteries.
• Atherosclerosis and/or vasospasm
- Supply demand imbalance (e.g. exercise).
- May be transient.
- Reversible.
, Myocardial Infarct (MI): - correct answer Myocardial tissue necrosis.
- Severe ischaemia or coronary artery occlusion.
- Acute thrombus.
- Irreversible.
Diagnosis - MI - correct answer 1. Clinical history of ischaemic chest pain (angina) > 15 min.
2. Changes in serial ECG tracings.
3. Evidence of cardiac biomarkers in blood (CK-MB, cTnT).
ECG changes with acute infarct (STEMI) - correct answer 1. T wave peaking followed by
inversion.
2. ST segment elevation. >1mm for 0.8s or longer after J point
3. Appearance of new Q waves.
- Typical to see all 3 stages, but any one may be present alone.
With MI, ST segment is bowed upwards and tends to merge with T wave, without clear
demarcation between them.
Why New Q Waves? - correct answer •Infarcted tissue is electrically silent.
Electrical axis shifts away from leads overlying infarcted
area.
• Wider and deeper than normal Q waves:
1. Q wave duration >0.04 s
2. Q wave depth at least 1/3 (or 1/4) height or R wave.
Reciprocal changes in other leads
• Tall R waves, ST (e.g. depression), T wave changes.
Non-ST Elevated MI (NSTEMI) - correct answer • Characteristics:
1. No pathological Q waves.
2. ST segment depression.
3. T wave inversion.
• Suggests incomplete occlusion of coronary artery.
Sinus (exit) block - correct answer - Failure of sinus impulse to propagate through the atria.
- cannot distinguish between sinus block and sinus arrest.
- ECG: missed beat or abnormally long PR interval
What makes up the AV junction? - correct answer Av node and Bundle of HIS
1st Degree AV block - correct answer PR interval >0.20s
- Increased inherent refractoriness of tissue or tissue degeneration
- More prevalent in athletes (6-33%) than general pop (<1%).
2nd Degree AV block - Mobitz type 1 - correct answer Wenckebach pattern: AV conduction
progressively impaired until failure - almost always in AV node.
- Asymptomatic unless ventricular rate is very slow.
- Transient and benign
2nd Degree AV block - Mobitz type 2 - correct answer Intermittent, sudden interruption to AV
conduction - usually below AV node.
- PR interval normal, but then missed QRS complex (beat)
- "Missed beat" can be regular or variable.
- P wave to P wave rhythm is normal
Which 2nd degree AV block is associated with disease? - correct answer Mobitz Type 2. Can
progress to type 3 AV block.
3rd degree AV block - correct answer - complete heart block
- No transmission of stimuli from atria to ventricles
- Atria & ventricles paced independently (AV dissociation)
- p waves are regular and faster than the QRS complexes (wide and aberrant)
- serious and potentially life-threatening
- stroke's adams attacks
Stroke's-Adams Attacks - correct answer fainting spells associated with complete heart block
,All bundle branch blocks are? - correct answer - usually distinct from any problem with AV
conduction
- Wide QRS complex >0.12s (highly variable pattern)
RBBB - correct answer - Delayed conduction through the right ventricle.
- V1 Rsr' (rabbit ears)
- V6 QRS complex (emphasis on S wave)
- ST depression & T wave inversions (V1-V3) also common (considered secondary changes)
- Benign or heart disease (e.g. pulmonary hypertension, degenerative disease of conduction
system)
How to tell if RBBB or LBBB is complete or incomplete? - correct answer - Complete: QRS>0.12s
- Incomplete QRS<0.12s
LBBB - correct answer - Delayed conduction through the left ventricle.
- Reversal of septal depolarisation (right to left)
- Loss of normal septal r wave in V1 and q wave in V6.
- V5-V6 (wide QRS - broad and notched)
- Secondary ST depression & T wave inversions in leads with tall R waves (left lateral).
Who gets RBBB and LBBB? - correct answer RBBB: disease but also common in normal hearts
LBBB: rare in healthy hearts
BBB precludes diagnosis of hypertrophy (voltage criteria)
Hemiblocks - correct answer • Block in one or more fascicles of the LBB.
• Characteristics: alteration of QRS axis with normal QRS duration.
- Left Anterior Hemiblock: Left axis deviation (> -45˚)
- Left Posterior Hemiblock: Right axis deviation (> 120˚)
• Only if other causes of RVH excluded
Bifascicular block - correct answer - Impaired conduction down 2 of 3 main fascicles.
Trifascicular block. - correct answer - Impaired conduction down all 3 fascicles.
Bifascicular Blocks examples - correct answer 1.
,RBBB + LAH:
a) QRS>0.12 s & RSr' in V1 and V2 (RBBB)
b) Left axis deviation (LAH)
RBBB + LPH
a) RBBB - QRS>0.12 s & RSr' in V1 and V2 (RBBB)
b) Right axis deviation (LPH)
Pacemakers - correct answer Indicated when the heart is not capable of sustaining an intrinsic
rhythm & the patient is symptomatic.
• usage increased
• Delivers an electrical current that triggers depolarisation.
- Demand pacemakers
• Placed in atria or ventricles alone OR both (A-V sequential).
What conditions do pacemakers usually treat/manage? - correct answer - 2nd degree AV block
type 2
- 3rd degree AV block
- AV block/bradycardia with symptoms
- AV block + BBB during acute MI
- Recurrent brady or tachy-arrhythmias
- Sinus node dysfunction (sick sinus syndrome)
Myocardial Ischaemia - correct answer Restriction of O2 and nutrients to regions of the
myocardium.
- Restriction of blood flow through one or more coronary arteries.
• Atherosclerosis and/or vasospasm
- Supply demand imbalance (e.g. exercise).
- May be transient.
- Reversible.
, Myocardial Infarct (MI): - correct answer Myocardial tissue necrosis.
- Severe ischaemia or coronary artery occlusion.
- Acute thrombus.
- Irreversible.
Diagnosis - MI - correct answer 1. Clinical history of ischaemic chest pain (angina) > 15 min.
2. Changes in serial ECG tracings.
3. Evidence of cardiac biomarkers in blood (CK-MB, cTnT).
ECG changes with acute infarct (STEMI) - correct answer 1. T wave peaking followed by
inversion.
2. ST segment elevation. >1mm for 0.8s or longer after J point
3. Appearance of new Q waves.
- Typical to see all 3 stages, but any one may be present alone.
With MI, ST segment is bowed upwards and tends to merge with T wave, without clear
demarcation between them.
Why New Q Waves? - correct answer •Infarcted tissue is electrically silent.
Electrical axis shifts away from leads overlying infarcted
area.
• Wider and deeper than normal Q waves:
1. Q wave duration >0.04 s
2. Q wave depth at least 1/3 (or 1/4) height or R wave.
Reciprocal changes in other leads
• Tall R waves, ST (e.g. depression), T wave changes.
Non-ST Elevated MI (NSTEMI) - correct answer • Characteristics:
1. No pathological Q waves.
2. ST segment depression.
3. T wave inversion.
• Suggests incomplete occlusion of coronary artery.
