Cardiac catheterization Notes
This is not necessarily the same as coronary angiography, although the two terms are sometimes used interchangeably.
Cardiac catheterisation is the process by which you gain catheter access to the veins or arteries of the heart. Thus, in the procedures of coronary angiography, and angioplasty, you perform cardiac catheterisation as part of the procedure.
Reasons for catheterisation
- Injection of dye in angiography
- Measurement of intracardiac pressures and oxygen saturations
- Passage of electrophysiological instruments
- Passage of angioplasty and valvuloplasty balloons
During catheterisation, the patient is usually awake throughout, and the catheter is guided by fluoroscopy.
Left heart catheterisation
This is performed via an arterial route. The catheter is usually inserted into the femoral artery (again, brachial artery is sometimes used), and then passed up the artery, and into the aorta. Eventually it reaches the aortic arch, and can be passed directly into the left ventricle.
- The radial artery is gaining favour as a preferred site – as some studies report fewere complications. it is also useful when there is femoral artery stenosis, or obesity obscures natural landmarks used to identify the femoral artery.
Uses
Assessment of:
- left ventricular function
- Severity of mitral and aortic valve disease
- Outflow tract obstruction
- Extent of coronary artery disease
- Allows biopsies to be taken – e.g. in cardiomyopathies
- Allows electrophysical provocation studies – e.g. for VT
- Allow placement of stents (PCI)
- Allows balloon valvotomy
Right sided catheterisation
- This is performed via the venous route. The catheter is inserted via the femoral, internal jugular, subclavian or forearm veins.
Uses
Allows:
- Measurement of cardiac output
- Measurement of left ventricular filling pressure
- Measurement of pulmonary artery wedge pressure (PWP) – this is the pressure in the pulmonary artery distal to an occlusion of the artery. This is useful because it provides an estimation of the left atrial pressure. It is useful in determining the cause of acute pulmonary oedema. This is likely to be present if there is a PWP >20mmHg. Normal physiological pressure is 6-12mmHg.
- Direct thrombolysis of the pulmonary artery for massive pulmonary embolism
- Insertion of electrodes for cardiac pacemaker devices
Measurement of the PWP can involve the insertion of a Swan-Ganz catheter (pulmonary artery catheter). This catheter is purely diagnostic and is used to monitor left and right ventricular function. This catheter is usually inserted via the internal jugular or subclavian vein.
Indications for Swan-Ganz:
- Shock (cardiogenic vs non-cardiogenic)
- Respiratory distresses
- Complicated MI
- Monitoring effects of drugs (e.g. ionotropes)
- Assesing fluid requirements
- Thrombolysis for PE
The procedure
- Not normally painful. Patient may feel a warm flushing sensation when the dye is used
- Patients may be given some sedation if they feel anxious – normally this is diazepam (did you know this is Valium?!)
- Patients with renal impairment (creatinine of over 200) will require 1L of IV saline at least 1 hour before the treatment to reduce the risk of x-ray contrast nephropathy
Contraindications
There are no absolute contraindications. However, you still have to consider the relative risks for each patient. If they have a large number of relative risks you might want to reconsider giving the catheter. These include:
- Severe hypertension
- Shock
- Severe anaemia
- Acute renal failure
- Severe congestive cardiac failure
- Allergy to contrast
- Active infection or PUO
Also remember that catheterisation is part of other procedures (e.g. PCI) and thus not always just done on its own.
Complications
- Haemorrhage from entry site
- False aneurysm – this would need to be confirmed by ultrasound
- Dye reaction
- Infection
- Angina and MI
- Arrhythmias
- Pericardial tamponade
- Stroke
Notes by Tom Leach
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