ECG interpretation: Echocardiography and Cardiac Catherization.pptx

ECG interpretation

1. ECG interpretation, Echocardiography and Cardiac catheterization By Oladapo Oluwatimilehin (213375)

2. Electrocardiogram interpretation An electrocardiogram (ECG), also known as EKG, is a non-invasive test that records the electrical activity of the heart.
It’s a vital tool in cardiology, offering a glimpse into the heart’s rhythm and potential underlying issues. It provides information about chamber size.
It is the main test used to assess for myocardial ischaemia and infarction. How is an ECG generated? The basis of an ECG recording is that the electrical depolarisation of myocardial tissue produces a small dipole current which can be detected by electrode pairs on the body surface.
These signals are amplified and either printed or displayed on a monitor.

3. ECG INTERPRETATION P Wave: During sinus rhythm, the SA node triggers atrial depolarisation, producing a P wave.
Abnormal P wave morphology can indicate atrial enlargement, hypertrophy, or conduction abnormalities.

4. ECG INTERPRETATION Depolarisation proceeds slowly through the AV node, which is too small to produce a depolarisation wave detectable from the body surface. QRS complex: - The bundle of His, bundle branches and Purkinje system are then activated, initiating ventricular myocardial depolarisation, which produces the QRS complex. It lasts for about 0.10 seconds. - The muscle mass of the ventricles is much larger than that of the atria, so the QRS complex is larger than the P wave.

5. ECG INTERPRETATION The duration and morphology are crucial. A wide QRS complex (>120 ms ) suggests potential ventricular conduction delay or abnormal activation sequence. Injury to the left or right bundle branch delays ventricular depolarisation, widening the QRS complex. PR interval: The interval between the onset of the P wave and the onset of the QRS complex is termed the ‘PR interval’ and largely reflects the duration of AV nodal conduction. It reflects conduction time from the atria to the ventricles. A prolonged PR segment can suggest AV block.

6. ECG INTERPRETATION

7. T wave: Atrial repolarisation does not cause a detectable signal but ventricular repolarisation produces the T wave. Normally upright in most leads, T wave inversion can suggest ischemia, electrolyte imbalances, or cardiomyopathy. QT interval: - The QT interval represents the total duration Of ventricular depolarisation and repolarisation.
- Prolonged QT interval ( QTc > 450 ms ) increases the risk of arrhythmias.

8. ECG INTERPRETATION ST Segment : Represents the period between ventricular depolarization and repolarization. ST segment elevation can indicate acute ischemia, while depression might suggest ischemia or other etiologies .

9. ECG INTERPRETATION The standard 12–lead ECG The 12-lead ECG is generated from ten physical electrodes that are attached to the skin. One electrode is attached to each limb and six electrodes are attached to the chest.
In addition, the left arm, right arm and left leg electrodes are attached to a central terminal acting as an additional virtual electrode in the centre of the
chest (the right leg electrode acts as an earthing electrode). The twelve ‘leads’ of the ECG refer to recordings made from pairs or sets of these electrodes.
They comprise three groups: three dipole limb leads, three augmented voltage limb leads and six unipole chest leads (V1-V6)

10. ECG INTERPRETATION Dipole Limb Leads - Leads I, II and III are the dipole limb leads and refer to recordings obtained from pairs of limb electrodes.
- Lead I records the electric potential difference between the right (negative)
and left (positive) arms.
- Lead II: EPD between the right arm (negative) and left leg (positive).
- Lead III: EPD between the left arm (negative) and left leg (positive).
- These three leads thus record electrical activity along three different axes in the frontal plane.

11. ECG INTERPRETATION These three bipolar leads roughly form an equilateral triangle (with the heart at the center ) that is called Einthoven’s triangle in honor of Willem Einthoven, who developed the electrocardiogram in the early 1900s.

12. ECG INTERPRETATION Augmented voltage limb leads Leads aVR , aVL and aVF are the augmented
voltage limb leads. These record electrical activity between a limb electrode and a modified central terminal.

13. ECG INTERPRETATION

14. ECG INTERPRETATION For example, lead aVL records the signal between the left arm (positive) and a central (negative) terminal, formed by connecting the right arm and left leg electrodes. Similarly augmented signals are obtained from the right arm ( aVR ) and left leg ( aVF ).
These leads also record electrical activity in the frontal plane, with each lead 120° apart. Lead aVF thus examines activity along the axis +90°, and lead aVL along the axis −30°, and so on. The three augmented unipolar leads, coupled with the three standard bipolar limb leads, comprise the six limb leads of the ECG. The 6 chest leads (V1-V6) make it 12 in total.

15. ECG INTERPRETATION

16. ECG INTERPRETATION Note: When depolarisation moves towards a positive electrode, it produces a positive deflection in the ECG.
Depolarisation in the opposite direction produces a negative deflection. When the vector is at right angles to a lead, the depolarisation in
that lead is equally negative and positive (isoelectric).

17. ECG INTERPRETATION - In this figure, the QRS complex is isoelectric in aVL , negative in aVR and most strongly positive in lead II; the main vector or axis of depolarisation is therefore 60°. The normal cardiac axis lies between −30° and +90°.

18. ECG Correlates of Common Cardiac Conditions: Acute Coronary Syndrome (ACS): ST segment elevation in specific leads suggests ongoing ischemia. Conversely, ST segment depression can indicate ongoing ischemia or other aetiologies. Could be ST elevation Myocardial infarction (STEMI) or Non-ST elevation Myocardial infarction (NSTEMI).

19. ECG Correlates of Common Cardiac Conditions: 2. Arrhythmias : ECG findings vary depending on the specific arrhythmia. Atrial fibrillation shows irregular R-R intervals and absent P waves.

20. ECG Correlates of Common Cardiac Conditions: 3. Premature ventricular contractions (PVCs): There will be abnormal QRS morphology originating from the ventricles.

21. ECG Correlates of Common Cardiac Conditions: 4. Electrolyte Imbalances: Hyperkalemia can cause peaked T waves, while hypokalemia can lead to flat T waves and U waves.

22. Echocardiography Echocardiography, or cardiac ultrasound, is obtained by placing an ultrasound transducer on the chest wall to image the heart structures as a real-time, two.dimensional ‘slice’. This permits the rapid assessment of cardiac structure and function. Left ventricular wall thickness and ejection fraction can be estimated.

23. Echocardiography Doppler echocardiography: This is an ultrasound technique that uses the Doppler effect to assess blood flow within the heart. It works by bouncing sound waves off blood cells and analyzing the shift in frequency to determine how fast and in what direction the blood is moving.
This helps doctors evaluate heart valve function, detect abnormal blood flow patterns, and calculate how well the heart is pumping blood.

24. Echocardiography

25. Echocardiography 2. Transoesophageal echocardiography (TEE): Transthoracic echocardiography sometimes produces
poor images, especially if the patient is overweight or has obstructive airways disease. Some structures are difficult to visualise in transthoracic views, such as the left atrial appendage, pulmonary veins, thoracic aorta and interatrial septum. TEE is a special type of echocardiogram where a thin ultrasound probe is inserted through the esophagus to get a closer look at the heart.
It is done under light sedation and positioned at the back of the left atrium.

26. Echocardiography This can provide clearer images of certain heart structures, especially those at the back of the heart, compared to a regular echocardiogram done on the chest.
This technique produces high-resolution images, wh ich makes the technique particularly valuable for investigating patients with prosthetic (especially mitral) valve dysfunction, congenital abnormalities (e.g. Atrial septal defect), aortic dissection, infective endocarditis ( vegetations that are too small to be detected by transthoracic echocardiography) and systemic embolism (intracardiac thrombus or masses).

27. Echocardiography 3. Stress echocardiography: - This combines a regular echocardiogram with a stress test, such as exercise or medication administration, to see how the heart functions under stress.

- It is usually used to investigate patients with suspected coronary artery disease who are unsuitable for exercise stress testing, such as those with mobility problems or pre-existing bundle branch block.

- A two-dimensional echo is performed before and after infusion of a moderate to high dose of an inotrope, such as dobutamine .

28. Echocardiography Myocardial segments with poor perfusion become ischaemic and contract poorly under stress, showing as a wall motion abnormality on the scan. This helps diagnose coronary artery disease, a condition where plaque buildup narrows the arteries supplying blood to the heart muscle.

29. Cardiac catheterisation This involves passage of a preshaped catheter via a vein or artery into the heart under X-ray guidance, which allows the measurement of pressure and oxygen saturation in the cardiac chambers and great vessels; it also involves the the performance of angiograms by injecting contrast media into a chamber or blood vessel. Left heart catheterization - Left heart catheterisation involves accessing the arterial circulation, usually via the radial artery, to allow catheterisation of the aorta, LV and coronary arteries.
- Coronary angiography is the most widely performed procedure, in which the left and right coronary arteries are selectively cannulated and imaged, providing information about the extent and severity of coronary stenoses, thrombus and calcification.

30. Cardiac catheterisation This permits planning of percutaneous coronary intervention and
coronary artery bypass graft surgery.
- Left ventriculography can be performed during the procedure to determine the size and function of the LV and to demonstrate mitral regurgitation.
- Aortography defines the size of the aortic root and thoracic aorta, and can help quantify aortic regurgitation.
- Left heart catheterisation is a daycase procedure and is relatively safe, with serious complications occurring in fewer than 1 in 1000 cases.

31. Cardiac catheterisation Right heart catheterization Right heart catheterisation is used to assess right heart and pulmonary artery pressures, and to detect intracardiac shunts by measuring oxygen saturations in different chambers. For example, a step up in oxygen saturation from 65% in the right atrium to 80% in the pulmonary artery is indicative of a large left-to-right shunt that might be due to a ventricular septal defect.

32. Thank you.