Investigations

ECG

Measurement

Heart rate

PR interval, Normal: 0.12 – 0.20 seconds

QRS duration, Normal: 0.06 – 0.10 seconds

QT interval

QRS axis in frontal plane

Rhythm Analysis

Look at the pattern of the waves and see the abnormalities or consistencies

Conduction Analysis

Basically, look at PP intervals

Waveform Description

P wave: the activation/depolarization of the right and left atria

QRS complex: right and left ventricular depolarization

ST-T wave: ventricular repolarization

U wave: origin for this wave is not clear - but probably represents "after depolarizations" in the ventricles

PR interval: time interval from onset of atrial depolarization (P wave) to onset of ventricular depolarization (QRS complex)

QRS duration: duration of ventricular muscle depolarization

QT interval: duration of ventricular depolarization and repolarization

RR interval: duration of ventricular cardiac cycle (an indicator of ventricular rate)

PP interval: duration of atrial cycle (an indicator of atrial rate)

Transthoracic Echocardiogram

A test which is used to reflect images of the heart using ultrasound technology by means of a transducer (probe).

The transducer emits high frequency sound waves ( inaudible by the ear) which are directed to the heart. As the sound waves encounters different structures, they will be reflected back to the probe, which then will be interpreted as images (2D). Images will be shown on the screen.

Done by sonographer, interpreted by cardiologist, takes about 30-60 minutes.

Uses

Assess the size of heart chambers

Look at cardiac muscle and valves function

Blood clots and masses in the heart

Presence of defects between the heart chambers

Abnormalities of blood flow in the heart

Pericardial diseases (accumulation of fluid)

Transoesophageal echocardiogram (TOE)

-A scope containing an ultrasound transducer, is passed into the patient’s oesophagus

-Evaluate for left atrial thrombus

-To guide cardioversion unless a thrombus is found

Advantage over TTE

-Better view those structures located deeper in the body

-Travel less to the heart to minimize the attenuation of ultrasound signal -> enhancing image and Doppler quality

-Aorta, pulmonary artery, valves of the heart, both atria, atrial septum, left atrial appendage, and coronary arteries have better views with TOE.

-TEE has a very high sensitivity for locating a blood clot inside the left atrium.

-To evaluate, diagnose, and treat patients in the peri-operative period. Most commonly used during open heart procedures

Disadvantages

-Requires fasting patient

-Requires a team of medical personnel

-Longer

-Uncomfortable

-Risks with oesophageal perforation or adverse reactions with medication or anesthetic

CT/MRI

Computed tomography (CT) or magnetic resonance imaging (MRI): If atrial fibrillation ablation is planned, then 3-dimensional imaging technologies (CT scan or MRI) are often helpful to evaluate atrial anatomy. Imaging data can be processed to create anatomic maps of the left atrium and pulmonary veins.

Blood tests

Complete blood count, thyroid, hepatic, and renal function panels are often helpful, especially when ventricular rate is difficult to control. Help to rule out thyroid problems or other substances in the blood that may lead to atrial fibrillation.

Holter monitor

A portable machine that records all heartbeats. Records information about the electrical activity of the heart as a person goes about their normal activities for a day or two. A button can be pressed when symptoms are felt so that the doctor can know the heart rhythm present at that moment

Chest X-ray

Help the doctor to see the condition of the lungs and heart. Can be used to diagnose other conditions and rule out atrial fibrillation

Electrophysiology study

Help see if there is a problem with heartbeat