KHI1B - Cardiac. Reading an echocardiogram.

QT interval

depolarisation of ventricles to depolarisation. drug toxicity will cause longer timeline here

What does a normal heart beat cycle look like on the ECG?

A normal heart beat contains a P wave, a QRS complex, and an ST segment. The one you will want to pay particular attention to is the QRS complex, as this is the easiest one to use to calculate heart rate. The P wave is a small semi-circular shape located right before the tall QRS complex. It represents the electrical activity of the atria ("atrial depolarization"), which are the two small chambers located at the top of the heart. The QRS complex is the tallest most visible aspect of the ECG trace. It is usually pointy, like a tall, thin triangle and very easy to recognize. It represents the electrical activity of the ventricles ("ventricular depolarization"), which are the two large chambers located at the bottom of the heart that forcefully pump blood throughout the body. The ST segment directly follows the tall QRS complex. It is actually the flat area prior to the next semi-circular shape on the ECG (which is the T wave). The importance of this flat segment (the ST segment), located right after the QRS complex, is that it provides important information to physicians about things such as potential heart attacks. P wave : represents the depolarization & contraction of the atria. QRS complex : represents the depolarization & contraction of the ventricles T wave : represents the repolarization & relaxation of the ventricles.

What is an ECG?

An electrocardiogram, or ECG, measures the electrical activity of the heart over a period of time. It is detected by electrodes attached to the surface of the skin, and recorded by a device external to the body. An ECG measures the electrical activity of the heart. The test itself does not send out any electricity; it merely records the natural electrical impulses of the heart cells. This, in turn, provides valuable information to your doctor about your heart rate, your heart rhythm (and whether it is regular or irregular), and the strength and coordination of each heartbeat as the impulses travel through the various aspects of the heart muscle. Although heart rate can be calculated easily by taking a pulse, an ECG may be necessary to determine if there is any damage to the heart, how well a device or drug is working, whether the heart is beating normally, or to determine the location and size of the heart chambers.This test may also be performed to check for heart disease, to check for heart problems, or to determine if someone's heart is healthy enough for surgery

How do I determine heart rate on a ECG (part 1) (Regular heart rate).

Count the space between QRS complexes. The next step is to determine the number of large squares on the ECG trace separating one QRS complex from the next QRS complex. The ECG normally has both small squares and large squares. Be sure you are using the large squares as your reference point. Go from the peak of one QRS complex to the peak of the following QRS complex. Note the number of large squares separating the two points. Often, it will be a fractionated number as the complexes will not land exactly on the squares; for instance, 2.4 squares or 3.6 squares may separate adjacent QRS complexes. There are normally 5 little squares embedded in each large square, allowing you to approximate the distance between QRS complexes to the nearest 0.2 units (because 1 big square divided into 5 small squares gives you markings every 0.2 units).

How to determine heart rate on a ECG - part 2 - regular heart rate.

Divide the number 300 by your answer above. Once you have calculated the number of big squares separating QRS complexes (let's use 3.2 as an example), perform the following calculation to determine heart rate: 300/3.2 = 93.75. If there are 4 squares in an R-R interval 300/4 = 75 beats per minute Round your answer to the nearest whole number. In this case, the heart rate would be 94 beats per minute.

Identifying the QRS complex on the ECG.

Identify the QRS complex. The QRS complex is normally the tallest part of the pattern that repeats on the ECG. It is a tall and skinny spike (for a person with normal heart function) that occurs repeatedly at the same rate across the ECG trace. Every time one QRS complex occurs, it is an indication that one heart beat has taken place. Therefore, you can use the space between QRS complexes on the ECG to calculate the heart rate.

How to determine heart rate on a ECG - if there is irregular rhythm.

If the rhythm is irregular: Count the number of complexes on the rhythm strip (each rhythm strip is 10 seconds long) Multiply the number of complexes by 6 (giving you the average number of complexes in 1 minute)

ST elevation - what does it mean?

ST elevation ST elevation is significant when it is > 1mm (1 small square) in relation to the baseline. It is most commonly caused by acute myocardial infarction. The morphology of the ST elevation differs depending on how long ago the MI occurred.

2. Determine heart rhythm.

The heart rhythm can be regular or irregular. Irregular rhythms are regularly irregular (i.e. a recurrent pattern of irregularity) or irregularly irregular (i.e. completely disorganised) Mark out several consecutive R-R intervals on a piece of paper, then move them along the rhythm strip to check if the subsequent intervals are the same. Hint - if you are suspicious that there is some atrioventricular block, map out the atrial rate and the ventricular rhythm separately (i.e. mark the P waves and R waves). As you move along the rhythm strip, you can then see if the PR interval changes, if QRS complexes are missing or if there is complete dissociation between the two.

1. determine heart rate. The first thing to do is to determine the heart rate.

There re 2 ways of doing this: 1. if there is a regular heart rate. 2. if there is an irregular heart rate. An easier rate is just to look at the chart. If there are a lot of PQRST complexes - the heart is beating fast (tachycardia); if there are not that many PQRST complexes on the strip its beating slow (brachycardia).

P wave

atrial depolarisation

angina vs non stemi

flow chart i lilley Stemi - chest pain, poz bio markers. Stemi - st elevantion ST in it stands for ST elevation. NON- STEMI - ST isn't elevated. Angina - ST depression and no biomarkers.

PR segment

long interval = conduction delay short interval - in wolf parkinson syndrome.

ST depression

non stemi - ischemia. angina

atrial flutter - sawtooth

prob with atrium.

avr

should always be negative. Thats just the view of heart that u get from that angle. If POZ the u have leads on wrong or theree is an abnormality

QRS

ventricular depolarisation

VF and VT cardiac arrest rhythms.

ventricular fibrillation and Ventricular Tachycardia. MI damages the , schema in electrical pathways, sodium potassium pump stuffs - VT - big and wide QRS complexes VF: ventricular fibrillation: heart has lost organised contraction, myocytes just firing off at random. sitting there quivering.

T

ventricular re-polarisation