cardiac catheterization

What’s new?

C With improvement in technology and miniaturization of equip-

ment, radial access is increasingly being used for routine cardiac

catheterization.

C Catheters have been designed that enable engagement of both

INVESTIGATIONS

Cardiac catheterizationDeepak Goyal

Karim Ratib

Rajay Narain

Jim Nolan
left and right coronary ostia with the same catheter, limiting the
need for catheter exchanges.

C Vascular closure devices have been developed to aid in

managing femoral arterial punctures.

C The requirement for cardiac catheterization has been reduced

by comprehensive non-invasive imaging, but it remains the

gold standard for quantifying disease severity and planning

therapy for many patients with severe cardiac disease.

AbstractCardiac catheterization involves insertion of fine-bore tubes (catheters)

into the heart through cannulae inserted into a peripheral artery or

vein. Procedures are commonly performed via the femoral vessels.

However, the radial artery approach has the best safety record and is

becoming increasingly popular. Brachial access is now rarely used

because of its complexity and potentially higher complication rates.1

Left heart catheterization is used to diagnose or evaluate coronary artery

disease and valvular heart disease. Left ventriculography, selective coro-

nary angiography and measurement of pressure in the left ventricle (LV)

are routinely performed. Aortography is performed in patients with aortic

regurgitation or aortic root dilatation. Left ventriculography allows visual

assessment of LV size/function as well as measurement of LV pressure

and systolic pressure gradients across diseased aortic valves. Coronary

angiography provides information on coronary anatomy. Right heart cath-

eterization allows measurement of haemodynamic data and oxygen satu-

rations from the right heart chambers and pulmonary circulation. It

provides information on right ventricular function, pulmonary artery pres-

sure, right-sided and left-sided filling pressures, cardiac output and left-

to-right shunts. Combined right and left catheterization is used in the

comprehensive evaluation of patients with complex cardiac conditions,

particularly those with valvular heart disease, intra-cardiac shunts or

heart failure.2

Keywords aortography; cardiac catheterization; coronary angiography;

right heart catheterization; ventriculography

Introduction

Cardiac catheterization involves insertion of fine-bore tubes

(catheters) into the heart through a cannula in a peripheral artery

Deepak Goyal MD MRCP is Specialist Registrar in Cardiology in the West

Midlands Deanery, UK. Competing interests: none.

Karim Ratib MRCP is Cardiology Research Fellow at the University

Hospital of North Staffordshire, Stoke-on-Trent, UK. Competing

interests: none.

Rajay Narain MRCP is Specialist Registrar in Cardiology in the West

Midlands Deanery, UK. Competing interests: none.

Jim Nolan MD FRCP is Consultant Cardiologist in the Cardiothoracic

Centre at the University Hospital of North Staffordshire, Stoke-on-Trent,

UK. Competing interests: none.

MEDICINE 38:7 390

or vein under fluoroscopic guidance. The first human heart

catheterization was performed in 1929, when Werner Forssman

inserted a catheter into his own heart via a cut-down of his left

antecubital vein. Modern invasive and interventional cardiology

began when Mason Sones obtained the first selective coronary

angiogram in 1958, using a brachial artery cut-down technique.3

The introduction of the Seldinger technique and development of

pre-shaped catheters in the late 1960s established the femoral

approach as the preferred method. The radial artery approach,

which has better procedure-related vascular complication rates,

was introduced in 1989 by Campeau and has been rapidly

adopted by many cardiologists as their access site of choice.4

Left heart catheterization involves injection of contrast into

the left ventricle (ventriculography) and selective coronary

angiography. Pressures in the left ventricle and aorta are also

measured. Right heart catheterization involves passing a catheter

through the right heart chambers into the pulmonary circulation,

and provides additional haemodynamic data. Some of the hae-

modynamic data obtained rely on several assumptions, and so

must be interpreted together with information from other sources

and assessment of the patient’s clinical condition.

Indications

Patients with known or suspected coronary artery disease or

aortic valve disease usually undergo left heart catheterization to

clarify the diagnosis and to help in planning an optimal treatment

strategy. Left ventricular catheterization allows visual assess-

ment of left ventricular (LV) function and size, measurement of

LV end-diastolic pressure (LVEDP) and the systolic pressure

gradient across the aortic valve. Coronary angiography provides

information on coronary anatomy. Aortography is also per-

formed in those with aortic regurgitation, aortic root dilatation or

during assessment for aortic valve interventions.

Patients with mitral, tricuspid or pulmonary valve disease,

heart failure, pericardial constriction or suspected intra-cardiac

shunts, and those being assessed for cardiac transplantation

usually undergo both right and left cardiac catheterization. Right

heart catheterization provides haemodynamic information on

pulmonary and tricuspid valve gradients, right ventricular func-

tion, pulmonary artery pressure, right-sided and left-sided filling

� 2010 Published by Elsevier Ltd.

Figure 1 Angiogram demonstrating the left coronary artery anatomy in the

left anterior oblique view. The left coronary artery arises from the proximal

ascending aorta as the left main stem (LMS). This bifurcates into the

circumflex artery (Cx) and the left anterior descending artery (LAD).

Branches of the LAD are the septal arteries which supply the septum and

INVESTIGATIONS

pressures, cardiac output and left-to-right shunts. Simultaneous

left heart catheterization allows assessment of LV and mitral

valve function and associated coronary disease.

Pre-catheterization evaluation

This should include a full medical history, with particular

emphasis on co-morbidities such as diabetes, kidney disease and

anticoagulation status. Any previous allergies to contrast medium

or latex should be recorded. Full procedural details relating to

previous cardiac or peripheral arterial interventions or cardiac

surgery should also be obtained along with a physical examina-

tion and ECG. Routine laboratory tests should include a full blood

count including platelet count, serum electrolytes and creatinine,

plasma glucose and an international normalized ratio. Patients

with diabetes taking metformin should omit this drug on the

morning of the procedure and for 2 days after it. Patients with

a history of contrast medium allergy should be given prophylaxis

with corticosteroids and antihistamines. Patients with chronic

renal impairment are susceptible to contrast nephropathy, and

require pre-treatment with fluid loading and acetylcysteine, and

use of low-nephrotoxicity contrast agents.5

Procedures

the diagonal arteries (Dx). Branches of the circumflex artery (Cx) are called
Left heart catheterization obtusemarginals (OM). The circumflex artery (Cx) is dominant. This artery is
free from disease.
Left heart catheterization is commonly performed via a sheath
positioned in the right femoral artery. The sheath is inserted

using a Seldinger technique, and a side-hole catheter (usually

a pigtail catheter) is passed over a J-tipped guide-wire to the

aortic root and across the aortic valve into the left ventricle. A

straight guide-wire is used to cross the valve in patients with

aortic stenosis. If good echocardiographic data are available, it is

often unnecessary to cross a severely stenosed aortic valve, as

the non-invasive test will provide sufficient information on

stenosis severity and left ventricular function.6

With the catheter in the left ventricle, pressure is recorded and

the end-diastolic pressure measured. Ventriculography is per-

formed using a mechanical power injector. Pressure is then

recorded as the catheter is withdrawn across the aortic valve;

a decrease in pressure indicates the presence of aortic stenosis.

The catheter may also be placed above the aortic valve and

a further power injection performed to image the ascending aorta

and assess aortic regurgitation (aortography).

Selective coronary angiography is then performed. In about

90% of transfemoral diagnostic studies, Judkin’s catheters are

used. These are pre-shaped end-hole catheters that are designed

to engage the coronary ostia with minimal manipulation. In the

other 10% of cases, catheters of various shapes are used,

depending on the size and orientation of the aortic root and the

relative positions of the coronary ostia. The left and right coro-

nary arteries (Figure 1) are imaged in several different projec-

tions, using 5e10 mL of contrast for each view. Typically, six to

eight views of the left coronary artery and three of the right

coronary artery are obtained. These angiographic images are

used to detect and quantify the presence of stenotic coronary

lesions. When the procedure is completed, the catheters and

sheath are removed and manual pressure applied to the femoral

puncture sites to obtain haemostasis. As an alternative, vascular

closure devices can be used to close the vascular puncture

rapidly and reduce the need for bed rest.

MEDICINE 38:7 391

Right heart catheterization

The femoral vein is the most commonly used access site for right

heart catheterization. A sheath is placed in the vein using

a percutaneous Seldinger technique and a pre-shaped end-hole

catheter is passed into the right atrium, the right ventricle and the

pulmonary artery using standard manipulations under fluoro-

scopic control. Pulmonary artery pressure is recorded, and the

catheter is advanced until it plugs a branch of one of the pulmonary

arteries and the waveform changes to a pulmonary capillary

wedge (PCW) tracing closely matched to the left atrial pressure.

When mitral valve disease is suspected, simultaneous left

heart catheterization is performed and the LV and PCW pressures

are recorded simultaneously. Any difference between these

measures in end-diastole indicates mitral stenosis.

The pulmonary artery catheter is then withdrawn and pres-

sures in the pulmonary arteries, the right ventricle and the right

atrium are measured sequentially (Figure 2). Left-to-right intra-

cardiac shunts are assessed using a ‘saturation run’, in which

blood samples withdrawn from the pulmonary artery, the right

ventricle, the right atrium and the caval veins are analyzed and

their oxygen saturations compared. In patients who have

a significant left-to-right shunt, oxygenated blood enters the right

heart via a defect (such as an ASD, PDA or VSD) and produces an

abnormal increase in oxygen saturation (the magnitude of this

increase is proportional to the size of the shunt and this allows

quantification of the lesion).7

Flexible, balloon-tipped catheters may also be used to

measure right heart pressures and cardiac output in ICUs and

coronary care units (e.g. the SwaneGanz catheter). They are

commonly inserted via the subclavian, femoral or jugular vein,

and are floated across the tricuspid and pulmonary valves; in

many cases fluoroscopic guidance is not needed. With the


Right heart withdrawal in a patient with mild pulmonary hypertension

Normal values

• Right atrium mean < 5 mm Hg

• Right ventricle < 25 mm Hg systolic, < 5 mm Hg diastolic

• Pulmonary artery < 25 mm Hg systolic, < 10 mm Hg diastolic

• Pulmonary capillary wedge mean 4–12 mm Hg, left ventricular

end-diastolic < 10 mm Hg

Pre

ssu

re (

mm

Hg

) 40

20

Pulmonary

capillary wedge

Pulmonary artery

Right

ventricle

Right

atrium

Figure 2

INVESTIGATIONS

catheter positioned in the pulmonary artery, intra-cardiac pres-

sures and cardiac output can be estimated and used to guide the

administration of fluids and cardiac drug therapy.

Alternative access sites

The brachial artery can be used for cardiac catheterization.

Brachial artery access may be achieved using a cut-down

procedure or a Seldinger technique. In the cut-down procedure,

an incision is made in the skin over the brachial artery and

catheters are inserted via an arteriotomy under direct vision. This

is now seldom used because of its technical complexity and

much higher complication rate. Percutaneous brachial proce-

dures are technically simpler, but also have a reported high

complication rate, and are not widely used by cardiologists.8

Increasingly, more diagnostic and interventional coronary

procedures are being performed via the radial route. Data from

the British cardiac intervention society demonstrate a rapid

increase in the use of this access site. In 2004, 10.2% of all

coronary intervention was performed via the radial route,

increasing to 34.6% in 2008.9 The radial artery is currently the

safest access site, with minimal neurovascular complications

related to its favourable anatomy. It is superficial and easily

compressible, and any bleeding can therefore be easily

controlled. In addition, no major veins or nerves lie close to the

artery, thereby limiting the risks of neurological damage and

arteriovenous fistula formation. Other benefits include imme-

diate ambulation and greater post-procedure comfort for the

patient, early discharge and lower costs.10

Before performing a transradial procedure, most operators

perform an Allen test to demonstrate that the ulnar artery is patent

and capable of perfusing the hand if the procedure results in radial

occlusion. In about 1e2% of patients, the Allen test is unfav-

ourable, indicating insufficient collateral ulnar circulation to the

hand, and radial access should be avoided. Specific radial puncture

systems are used to insert a sheath into the radial artery close to the

wrist via a Seldinger approach. Specific catheters have been

MEDICINE 38:7 392

developed to allow cannulation of both coronary ostiawith a single

specific transradial catheter, although it is also possible to use

conventional transfemoral catheters. A medial antecubital vein

may be cannulated for simultaneous right heart catheterization.11

After completion of the procedure simple devices are used to apply

compression to the radial puncture site to achieve haemostasis.

Effective use of the transradial approach is associated with an

important learning curve and experience is necessary to puncture

the small calibre radial artery without inducing arterial spasm

which complicates manipulation of the catheter. There has been

some (mostly observational) data suggesting that the radial route

is associated with increased radiation doses to the patient and

operator. These studies have not controlled for operator experi-

ence and use of radiation protection devices, and the data may

not be reliable. Improvement in equipment design and anatom-

ical knowledge have reduced the time taken for radial operators

to become competent. For experienced operators the use of radial

access does not result in any significant increase in technical

complexity, radiation exposure or procedural duration, and does

not reduce the likelihood of success.2

Interpretation of haemodynamic data

� Low PCW pressure or LVEDP indicates hypovolaemia; high

values indicate incipient LV failure or fluid overload.

� Raised pulmonary artery pressure (pulmonary hypertension)

may result from chronically raised left heart filling pressures in

mitral valve disease or heart failure, from long-standing left-to-

right shunts, or from intrinsic lung disease. It is an adverse

prognostic factor and indicates increased operative risk.

� Pulmonary vascular resistance is calculated from the trans-

pulmonary gradient (mean pulmonary artery pressure minus

mean PCW) and cardiac output, and is a critical measurement

in the assessment of patients for cardiac transplantation.

� Mitral regurgitation may produce giant ‘v’ waves in the PCW,

and values of 35 mmHg or more indicate moderate-to-severe

regurgitation. This is a useful marker of the severity of


Formulae used for haemodynamic data

C Left-to-right shuntPulmonary flow

Systemic flow¼ SaO2 �MVO2

98� PaO2SaO2, aortic oxygen saturation; PaO2, pulmonary artery saturation

MVO2 ¼ (3 � superior vena cava saturation þ inferior vena cava

saturation)/4

C Aortic valve area (cm2)

(Gorlin formula)

Cardiac output (L/min)

(Opening time/beat) � heart rate � Omean gradient (mmHg) � 44$3C Mitral valve area (cm2)

(Gorlin formula)

Cardiac output (L/min)

Opening time/beat � heart rate � Omean gradient (mmHg) � 37$7

C Cardiac output (L/min)

(Fick principle)

Oxygen consumption (mL/min)

1.36 (SaO2 � PaO2) � haemoglobin concentration (g/L)

Table 1

INVESTIGATIONS

regurgitation, but the size of the ‘v’ wave is considerably

affected by left atrial compliance.

� The transmitral gradient (PCW � LVEDP) is a measure of the

severity of mitral stenosis. End-diastolic gradients of more

than 5 mmHg are significant, and gradients of 12e16 mmHg

are typically seen in severe stenosis. However, the size of the

gradient depends on heart rate and cardiac output, and this

technique has been superseded by echocardiographic criteria.

Mitral valve area derived from the Gorlin formula (Table 1) is

more reliable, but requires estimation of cardiac output.

� The pull-back aortic gradient (Figure 3) is an important

measure of the severity of aortic stenosis; a gradient of 50

mmHg or more prompts consideration of valve replacement.

Echocardiography measures instantaneous gradients, which

are typically 10 mmHg or more greater than pull-back gradi-

ents, and this may lead to significant overestimation of the

severity of aortic stenosis. However, if LV function is poor,

the pull-back gradient is reduced, and estimation of valve

area using echocardiography or the Gorlin formula is a more

accurate guide to severity.

Pressure during pull-back across the aortic valve50 mm Hg

Pre

ssu

re (

mm

Hg

)

100

50

Figure 3

MEDICINE 38:7 393

� Left-to-right intra-cardiac shunts are assessed by comparing

oxygen saturations in the superior vena cava, the inferior

vena cava, the high, mid and low right atrium, the right

ventricle and the pulmonary artery. An increase in saturation

of more than 7% suggests a left-to-right shunt. Small shunts

may not be detected. The magnitude of the shunt is measured

in terms of the relative blood flows in the systemic and

pulmonary circulations.

� Cardiac output is measured using a thermodilution method or

by the Fick principle. The Fick principle calculates cardiac

output from oxygen consumption (measured using ametabolic

hood or a Douglas bag) and the arteriovenous difference in

oxygen content (measured from blood samples taken in the

pulmonary artery and aorta). Alternatively, oxygen consump-

tion can be estimated as 3ml O2/kg bodyweight, but this is less

accurate.

Complications

Major complications (e.g. major haemorrhage, myocardial infarc-

tion, stroke, major arrhythmia, death) occur in 0.25% of patients,

, showing a peak-to-peak gradient of

50 mm Hg


INVESTIGATIONS

and are more common in those with advanced cardiac disease.

Minor complications (e.g. vasovagal reactions, urticaria) occur in

about 5% of patients. Predictors of significant complications

include advanced New York Heart Association functional class,

hypotension, shock, aortic valve disease and renal insufficiency.

Access site-related neurovascular complications are common with

thebrachial artery approach andoccur in about 1e2%of caseswith

the femoral approach. With the radial approach, the risk of access

site complications is significantly lower.

Conclusions

Although non-invasive imaging (in the form of echocardiography,

cardiac CT and magnetic resonance scanning) is useful in many

patients, cardiac catheterization remains the gold standardmethod

of evaluating serious cardiac disease, and is mandatory in many

patients before percutaneous or surgical treatment. Advances in

equipment design and catheterization techniques, particularly the

use of the radial access site, have improved the tolerability and

safety of cardiac catheterization procedures. Cardiac catheteriza-

tionwill continue to play an important role in the investigation and

management of cardiac patients for the foreseeable future. A

REFERENCES

1 Davis C, VanRiper S, Longstreet J, Moscucci M. Vascular complications

of coronary interventions. Heart Lung 1997; 26: 118e27.

2 Butler R, Gunning M, Nolan J. Essential cardiac catheterization.

London: Hodder Arnold, 2008.

3 Forssmann W. Uber die Wirkung der Leberfutterung auf das rote

Blutbild and den Cholesterinspiegel im Serum des gesunden

MEDICINE 38:7 394

Menschen Friedrich-Wilhelms Universitat, Inaugural-Dissertation,

Berlin, February 1929 (The report of first human heart catheterization

e a self experiment by Werner Forssman).

4 Agostoni P, Biondi-Zoccai GG, de Benedictis ML, et al. Radial versus

femoral approach for percutaneous coronary diagnostic and

interventional procedures; systematic overview and meta-analysis of

randomized trials. J Am Coll Cardiol 2004; 44: 349e56.

5 Scanlon PJ, Faxon DP, Audet AM, et al. ACC/AHA guidelines for

coronary angiography. A report of the American College of Car-

diology/American Heart Association Task Force on practice guidelines

(Committee on Coronary Angiography). Developed in collaboration

with the Society for Cardiac Angiography and Interventions. J Am Coll

Cardiol 1999 May; 33: 1756e824.

6 Omran H, Schmidt H, Hackenbroch M, et al. Silent and apparent

cerebral embolism after retrograde catheterisation of the aortic

valve in valvular stenosis: a prospective, randomised study. Lancet

2003 Apr 12; 361: 1241e6.

7 Gorlin R, Gorlin S. Hydraulic formula for calculations of stenotic mitral

valve, other cardiac valves, and central circulatory shunts. Am Heart J

1951; 41: 1e29.

8 Kiemeneij F, Laarman GJ, Odekerken D, Slagboom T, van der Wieken R.

A randomized comparison of percutaneous transluminal coronary

angioplasty by the radial, brachial and femoral approaches: the access

study. J Am Coll Cardiol 1997; 29: 1269e75.

9 Ludman P. BCIS dataset 2007, 2008, 2009.

10 Freestone B, Nolan J. Transradial cardiac procedures e the state of

the art. Heart, in press.

11 Lo TS, Buch AN, Hall IR, Hildick-Smith DJ, Nolan J. Percutaneous left

and right heart catheterization in fully anticoagulated patients

utilizing the radial artery and forearm vein: a two-center experience.

J Interv Cardiol 2006; 19: 258e63.


cardiac catheterization

Documents