Cardiac Catheterisation

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

The catheter is manipulated under fluoroscopic guidance. The patient is usually awake and on a cardiac monitor throughout. Most diagnostic studies are conducted as day-cases.

This is performed via the arterial route:

• The femoral artery has been the most commonly used access point.
• The brachial artery may be used. This is usually done percutaneously rather than with surgical exposure of the artery.
• The radial artery is gaining favour as an access site and many studies report fewer local complications for a range of different interventions.^{1,2,3,4,5,6,7} It is useful particularly when:
  • There is significant femoral artery atherosclerosis.
  • Obesity obscures anatomical landmarks.
  The disadvantages are that the technique is technically more difficult. For example manipulation of the catheter can be difficult because of arterial spasm.

Diagnostic uses

Cardiac catheterisation allows for more definitive testing in patients with confusing histories or clinical presentations of chest pain of uncertain origin. It also allows for diagnostic confirmation and more detailed information after noninvasive studies.
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)⁸
• Left ventricular biopsies may be taken (for example in cardiomyopathies)
• Electrophysiological provocation studies can be performed (for example for ventricular tachycardia)

Therapeutic interventions

Detailed analysis of the merits of such interventions is beyond the scope of this article. Such interventions include:

• Percutaneous Transluminal Coronary Angioplasty (PTCA)
• PTCA and stenting
• Treatment of acute coronary syndromes by PTCA/stenting – a Cochrane review and others cautiously favour stents over PTCA due to reduced risk of reinfarction and recurrent vessel occlusion.^9,10 Whether acute coronary syndromes are best treated by early invasive intervention is currently uncertain. This is one area that is subject to rapid change, with the introduction of new drugs, such as glycoprotein IIb/IIIa inhibitors, which have been shown to have clear benefit in high-risk ACS when used in combination with PTCA or stenting.
• Treatment of acute MI. The jury is still out on whether PTCA should replace thrombolysis as the first-line treatment for MI. There appear to be advantages to PTCA in terms of short term outcome but there are some drawbacks as well.
• Balloon valvuloplasty
• Septal infarction by alcohol injection for Hypertrophic Obstructive Cardiomyopathy (HOCM)

This is performed by the venous route, via the femoral, internal jugular, subclavian veins or forearm veins.⁶

Diagnostic uses

Right heart catheterisation allows:

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

Therapeutic interventions

These include:

• 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

In the critically ill patient, right heart catheterisation with a Swan-Ganz Catheter may be used for acute monitoring of left and right ventricular function, to guide treatment and monitor the effects of intervention. It has no direct therapeutic function. The catheter is usually inserted via the internal jugular or subclavian vein.
Potential indications include:

• Shock (cardiogenic versus non-cardiogenic)
• Respiratory distress (cardiogenic versus non-cardiogenic)
• Complicated MI
• Monitoring effects of drugs (for example cardiac inotropes)
• Assessing fluid requirements in patients with (for example multi-organ failure)
• Thrombolysis for pulmonary embolism

This will include:

• Investigations:Day case angiography does not usually require any routine pre-procedure investigations other than:
  • ECG.
  • Bloods:
  • FBC
  • U&E
  • Clotting studies
  • Group and Save
• Full explanation of the procedure with informed consent: It is not usually painful, although the injection of dye causes a warm flushing sensation.
• Pre-medication: Anxious patients may require pre-medication with oral or iv diazepam.
• Other considerations: Patients with renal impairment (creatinine >200) requires 1 litre of normal saline iv over 1 hour before and after angiography to prevent x-ray contrast nephropathy. This may be problematic where there is associated heart failure.

Once consent has been given there are no absolute contraindications to cardiac catheterisation. The outcome of the procedure should have potential benefit greater than the risk associated with the procedure. However a widespread risk-averse strategy to angiography may be preventing higher-risk patients from having revascularisation procedures.¹¹

• Relative contraindications include:
  • Severe hypertension
  • In shocked patients (for example in acute gastrointestinal haemorrhage)
  • Severe anaemia
  • Acute renal failure
  • Severe congestive cardiac failure
  • Allergy to contrast media
  • Active infection or unexplained fever
• Caution is required in higher risk patients, for example in:
  • Extremes of age (under 1 year and over age 60¹²)
  • Severe coronary artery disease affecting left main stem
  • New York Heart Classification class IV
  • Left ventricular ejection fraction <30%
  • Valvular heart disease
  • Renal insufficiency
  • Diabetes (type 1)
  • Peripheral vascular disease
  • Cerebrovascular disease
  • Chronic obstructive pulmonary disease

Complication rates are low. However it is the view of the Joint Audit Committee of the British Cardiac Society and the Royal College of Physicians that they could be lower still, helped by an improved system of audit and formal reporting.¹³

• Mortality for routine coronary angiography is between 0.08 and 0.1% in most centres.^8,14
• Haemorrhage from arterial puncture site – apply pressure
• False aneurysm (a firm, pulsatile swelling) – confirm with ultrasound
• Dye reaction – skin reactions, nausea and vomiting, transient cortical disturbance; usually settle <24 hours
• Infection – early fever is usually a dye reaction
• Loss of distal pulse(s)
• Angina and myocardial infarction
• Arrhythmias
• Pericardial tamponade
• Stroke
• Infection (relatively low rate)
• Renal dysfunction

• Claude Bernard (1813-1878), France's most famous physiologist, was the first to experiment with cardiac catheterisation in horses.
• Dr Werner Forssmann (1904-1979), was the first to pass a cardiac catheter, on himself, at the age of 25 in 1929. He was immediately fired for his efforts, and it is said that he only stopped when he had used all his veins with 17 cut downs. Discouraged by lack of acceptance he turned from cardiology to urology, though he was eventually rewarded with the Nobel Prize in 1956 (along with Cournand, and Richards) for his pioneering efforts.
• Andre Cournand (1895-1988), and Richards (1895-1973), were the first to employ the cardiac catheter as a diagnostic tool in 1941, after 10 years of work together. Andre Cournand had the distinction of serving as auxiliary battalion surgeon even before his first year of medical school ended, gaining the Croix de Guerre with three bronze stars for his work in the trenches of WW1. Dickinson Richards had gained a degree at Yale in English and Greek, before serving as artillery officer in WW1.