Cardiac Investigation

Front 1

Ambulatory ECG - What is it?

Back 1

Ambulatory electrocardiography (AECG) is used to detect, characterise and document cardiac arrhythmias in clinical practice. As some arrhythmias are infrequent or may occur only during certain activities (e.g., sleep or exercise), it is usual to record the electrical activity of the heart over a period of time, usually24 or 48 hours.

Front 2

Ambulatory ECG Equipement

Back 2

The most commonly used method of extended ECG recording is a Holter monitor. There are two commonly used types of recorder: continuous or intermittent

Front 3

Indications for Ambulatory ECG

Back 3

AECG may be used to assess patients in whom an arrhythmia is suspected, including:

• Patients with syncope, near syncope or dizziness.
• Patients with palpitations
• Patients who have had a cerebrovascular accident in whom paroxysmal atrial fibrillation (AF) or atrial flutter is suspected.
• Patients with episodic chest pain, shortness of breath or fatigue with no other obvious cause.
  

Front 4

Mobile cardiac outpatient telemetry

Back 4

This allows several days of ECG monitoring via a cellular-based transmission system Mobile cardiac outpatient telemetry (MCOT) provided a significantly higher yield than standard cardiac loop recorders in patients with symptoms suggestive of a significant cardiac arrhythmia. MCOT can detect asymptomatic clinically significant arrhythmias, and is particularly useful to identify the cause of presyncope or syncope, even in patients with previously negative investigations.

Front 5

Cardiac Cathetherisation - Why do it?

Back 5

Cardiac catheterisation with a venous or arterial long-line catheter allows:

• Injection of radio-opaque dye for angiography.
• Measurement of intracardiac pressures and oxygen saturations.
• Passage of electrophysiological instruments.
• Passage of angioplasty and valvuloplasty balloons.
  

Front 6

Arteries used in Left Heart Cathetherisation

Back 6

1. The femoral artery has been the most commonly used access point.
2. The brachial artery may be used. This is usually done percutaneously rather than with surgical exposure of the artery.
3. The radial artery is gaining favour as an access site and many studies report fewer local complications for a range of different interventions.
   

Front 7

Diagnostic Uses of Left Heart Cardiac Cathetherisation

Back 7

It can be used to assess

• Left ventricular function.
• Severity of mitral and aortic valve disease
• Outflow tract obstruction.
• The extent and severity of coronary artery disease(coronary angiography is the most common diagnostic study).
• Left ventricular biopsies may be taken (for example, incardiomyopathies).
• Electrophysiological provocation studies can be performed (for example, forventricular tachycardia)
  

Front 8

Therapeutic Uses of Left Heart Cardiac Cathetherisation

Back 8

• Percutaneous transluminal coronary angioplasty (PTCA).
• PTCA and stenting.
• Treatment of acute coronary syndromes (ACS) by PTCA/stenting
• Treatment of acute myocardial infarction.
• Balloon valvuloplasty.

Front 9

Veins used in Right Heart Cathetherisation Procedure

Back 9

• Femoral vein
• Internal jugular vein
• Subclavian veins
• Forearm veins
  

Front 10

Diagnostic uses of Right Heart Cathetherisation

Back 10

• Measurement of cardiac output, left ventricular filling pressure and pulmonary artery wedge pressure.
• Measurement of right heart oxygen saturations (for example, forseptal defects).
• Assessment of pulmonary hypertension(for example, prior tocardiac transplantation).
• Electrophysiological provocation studies
  

Front 11

Therapeutic uses of Right Heart Cathetherisation

Back 11

• Right-sided valvuloplasties.
• Radiofrequency ablation of, for example, the accessory pathway in Wolff-Parkinson-White syndrome.
• Direct thrombolysis into the pulmonary artery for massive pulmonary embolism.
• Insertion of electrodes for cardiac pacemaker devices.
  

Front 12

Cardiac Scinitgraphy - What is it?

Back 12

Myocardial perfusion scintigraphy (MPS) with single photon emission computed tomography (SPECT) uses a radio-pharmaceutical that is taken up into heart muscle in proportion to localised blood flow and stays in myocardial cells whilst scan is performed. Most use either thallium-201 or technetium-99m in proprietary compounds.

Front 13

Cardiac Scinitgraphy - Procedure

Back 13

Procedure:

• Stress test, e.g. treadmill, bicycle, IV adenosine or IV dobutamine.
• Thallium or technetium then injected.
• Image of myocardial perfusion then taken immediately and again over four hours after stress
  

Front 14

Coronary Calcium Score

Back 14

The presence of calcium in coronary arteries is almost always indicative of atherosclerotic plaque (but bears no relationship to plaque stability or instability).Cardiac risk factors and insulin resistance lead to progression of coronary artery calcification. CACS is determined by CT scanning which is non-invasive and can be of two types:

- Electron beam CT scan(EBCT).

- Multidetector CT scan(MDCT).

The amount of calcium detected in the coronary arteries is converted to a calcium score which correlates with the severity of the atherosclerosis.

Front 15

Coronary CT Angiography

Back 15

Coronary computed tomography angiography (CTA) is a non-invasive heart imaging test. High-resolution, 3-dimensional pictures of the moving heart and great vessels are produced during a coronary CTA to determine if either fatty or calcium deposits (plaques) have built up in the coronary arteries.Before the test, an iodine-containing contrast dye is injected into an IV in the patient's arm to improve the quality of the images. A medication that slows or stabilizes the patient's heart rate may also be given through the IV to improve the imaging results.During the test, which usually takes about 10 minutes, X-rays pass through the body and are picked up by special detectors in the scanner.

Front 16

Echocardiogram Techniques

Back 16

1. Cross-sectional- is two dimensional and gives the impression of a moving picture.
2. M-mode- uses a single static beam and appears as horizontal lines with superficial structures at the top and deep structures at the bottom.
3. Doppler- uses pulsed wave (useful for low-velocity flow, e.g. mitral valve flow), continuous wave (useful for high-velocity flow, e.g. aortic stenosis) and colour.
   

Front 17

Types of echocardiogram

Back 17

1. Transthoracic echocardiography (TTE) - the preferred investigation in valvular heart disease because all four cardiac valves can be seen and tested by Doppler, and other abnormalities in ventricular performance can also be assessed.
2. Trans-oesophageal echocardiography (TOE) - performed under sedation (usually with midazolam), the investigation of choice for the diagnosis of infective endocarditis, management of a hypotensive patient in the intensive care unit and in the search for a potential cardiac source of thromboembolism
3. .Stress echocardiogram - Can be used during or soon after exercise but an intravenous infusion of dobutamine is often used to induce stress similar to exercise.
   

Front 18

Exercise Tolerance Testing - Indications

Back 18

• Diagnosis of coronary heart disease
• Assessment of 'fitness' in certain occupations and medical conditions, eg the police force and some cardiomyopathies.
• Arrhythmias- ETT can help to record arrhythmias which are provoked by exercise (but only in those with non-life-threatening arrhythmias)
  

Front 19

Exercise Tolerance Testing Procedure

Back 19

ETT consists of exercising on a treadmill following a defined protocol, the Bruce protocol, over approximately 20 minutes. The test begins gently and gradually the level of intensity is increased through a combination of increased treadmill speed and incline. ECG is recorded throughout and blood pressure measured intermittently

Front 20

Contraindications for Exercise Tolerance Testing

Back 20

• Chest pain at rest or at night
• Any condition where left ventricular output is reduced
• Active systemic illness.
• Abnormal baseline ECG
• Suspected or confirmed life-threatening arrhythmias.