MED213 Clinical Insights: Understanding Electrophysiology

Flashcards based on MED213 Clinical Insights: Understanding Electrophysiology lecture notes.

What is the purpose of pre-participation screening based on ACSM guidelines?

Part of risk assessment and management; screens for signs/symptoms of CV, metabolic, or renal disease.

What are some exercise contraindications that would require referral to a GP?

Unstable angina, heart failure, uncontrolled arrhythmias, severe hypertension, symptomatic hypotension, acute infections

What are some exercise termination criteria?

Target HR achieved, chronotropic incompetence, hypertensive responses, drop in SBP, fatigue, arrhythmias, angina, patient request, equipment failure

How many seconds does each 1mm square last on an ECG?

1 mm square lasts 0.04 seconds.

What does the P wave represent?

Atrial depolarization

What does the QRS complex represent?

Ventricular depolarization

What does the PR interval represent?

The PR interval represents the time from the start of atrial depolarization to the start of ventricular depolarization.

What does the T wave represent?

Ventricular repolarization

What does the RR interval represent?

Distance between R-waves

What is the purpose of the PR segment?

Sets isoelectric line for ST

What occurs during Phase 0 of cardiac action potential?

Rapid influx of Na

What is the simplest form of understanding ECG waveforms?

Views of the heart. Whether the wave depolarization travels to the positive electrode, it is positive.

What areas does the Right Coronary Artery (RCA) supply?

Supplies the RA, RV, SAN and AVN supplying posterior LV

What areas does the Left Coronary Artery (LCA) supply?

LAD and CA which supply LA and LV

What is normal coronary blood flow?

250 ml min−1 (0.8 ml min−1 g−1 of heart muscle) = 5% of resting Q

Where does the deoxygenated blood leave the myocardial tissue of the LV and where does it drain?

via coronary sinus, drains into RA.

What causes coronary vasodilation during exercise?

Sympathetic activation

Which ECG leads are associated with the inferior region and the RCA?

II, III, aVF

Which ECG leads are associated with the antero-septal or antero-apical region and LAD?

V1-4

Which ECG leads are associated with the Antero-lateral region and CA?

V3-6

Which ECG leads are associated with the posterior region and RCA?

No specific leads

What rhythm is Sinus?

Regular rhythm.

What are Premature Ventricular Contractions (PVC's)?

Premature beat arising from an ectopic focus within the ventricles.

Are Multifocal PVC's more or less concerning than Unifocal PVC's?

More concerning

What is the course of action for Ventricular Fibrillation with rate 150 to 500/min?

DEFIB

What arrhythmia consists of more than 3 PVCs?

Ventricular Tachycardia (non-sustained)

What does Sustained VT do?

Impaired Q, reduced myocardial perfusion, could lead to VF.

How would you describe an ECG strip with Atrial Fibrillation (AF)?

erratic transmission of impulses at AV node, No P waves seen, QRS rate 170/min (variable), Fibrillatory waves

What risks does Atrial Fibrillation (AF) increase?

Increases risk of thrombosis/ embolism.

How would you describe an ECG strip with Wolf-Parkinson-White Syndrome?

Very short PR intervals (0.08s), 2nd A-V connection, Accessory pathway conducts quicker than AV node (pre- excitation), Sooner depolarisation shown by a delta wave

What would be prolonged on the ECG of someone with an Atrioventricular Block?

Prolonged PR interval

What does Right Bundle Branch Block (RBBB) cause?

Delayed electrical activation of RV

What are the characteristics of an RBBB on an ECG?

Wide QRS >3mm (120ms), RSR’ pattern in V1-3 (‘M-shaped’ QRS complex), Wide, slurred S wave in the lateral leads (I, aVL, V5-6), Sometimes ST depression/T wave inversion in the right leads (V1-3)

Should you do an exercise ECG test on someone with LBBB?

No

What happens to the ventricles during a Left Bundle Branch Block (LBBB)?

RV depolarises normally and first via RBB, Delayed electrical activation of LV as must be depolarised by the RBB with septal depolarisation from R to L, Distorted (notched/M) QRS shape due to abnormal depolarisation pathway

When can Left Ventricular Hypertrophy (LVH) be seen?

“Normal” in athletes or uncontrolled/long-lasting hypertension and aortic stenosis

How is LVH identified on an ECG?

S wave depth V1 + tallest R wave height in V5-V6 > 35 mm PLUS ST dep & T inversion in left-sided leads

What does Thickened walls from LVH lead to on an ECG?

Prolonged depolarisation (R) and delayed repolarisation (ST & T) in lateral leads

How much ST Depression is the most common and useful indication of myocardial ischemia?

≥1mm

What is ST Elevation a common indication of?

Most common and useful indication of myocardial infarction (STEMI)

What does the location of the ST elevation represent?

Region of infarct & likely artery occlusion

What artery is likely to be occluded during an Anterior STEMI (V2-V5)?

LAD artery

What are some highlighted causes of sudden cardiac death (SCD) in young sportspeople that can be detected via a resting ECG?

Congenital long QT syndrome, Brugada syndrome, Wolff-Parkinson-White syndrome

List the normal ECG Findings

Increased QRS voltage for LVH or RVH, incomplete RBBB, early repolarization/ST segment elevation, ST elevation followed by T wave inversion V1-V4 in black athletes, T wave inversion V1-V3 < age 16 years, Sinus bradycardia or arrhythmia, Ectopic atrial or junctional rhythm, 1° AV block, Mobitz Type 12° AV block

List the Borderline ECG Findings

Left axis deviation, Left atrial enlargement, Right axis deviation, Right atrial enlargement, Complete RBBB

List the Abnormal ECG Findings

T wave inversion, ST segment depression, Pathologic Q waves, complete LBBB, QRS ≥ 140 ms duration, Epsilon wave, Ventricular pre-excitation, Prolonged QT interval, Brugada Type 1 pattern, Profound sinus bradycardia < 30 bpm, PR interval ≥ 400 ms, Mobitz Type II 2° AV block, 3° AV block, ≥ 2 PVCs, Atrial tachyarrhythmias, Ventricular arrhythmias

What level of intensity should someone do if they have medical clearance.

If cleared, light to moderate.

What are key factors to consider regarding Exercise Contraindications?

Safety to YOU but safety for the participant is KEY!

What is the normal length in seconds of the PR interval?

0.12-0.22 s

What is the normal length in seconds of the QRS duration?

<0.12 s

What are the values for Corrected QT duration for men and women?

Corrected QT duration men: ≤ 0,45 s, Corrected QT duration women: ≤ 0,47 s