CATHLAB BASICS PRESENTED BYGABRIEL K FERNANDESCARDIOVASCULAR INTERVENTIONAL TECHNOLOGISTMETROPOLITAN HEART INSTITUTE & RESEARCH CENTRE INDIA LTD.IN ASSOCIATION WITH RADIOGRAPHERS ASSOCIATION OF MAHARASHTRA.

November, 1998 Council on Clinical Cardiology, American Heart Association

CARDIAC CATHETERIZATION LABORATORY

CONTENTS1 PREFACE2 INTRODUCTION3 THE HEART4 BLOOD PRESSURE5 CORONARY ARTERIES6 CARDIAC PROCEDURES7 BASIC PATHOLOGY OF THE

HEART

PrefaceThis book "Cardiac catheterization Basics" is aimed for technicians working in the cardiac catheterization room who quickly like to refresh their knowledge.The purpose of this book is to give a basic overview of the anatomy,physiology and pathology of the heart as a guidance for the catheterization procedure and to help to realize a good image quality.Since this book only provides limited information, It has to be considered only as an extra guidance tool.

IntroductionBlood circulationThere are two distinct systems in the body for the blood circulation:1.Pulmonary blood circulation2. Systemic blood circulation

Pulmonary circulation

The pulmonary arteries and veins carry blood from the heart to the lungs and return it to the heart. Blood which returns from the body to the heart is pumped into the lungs via the pulmonary artery to the lungs. With breathing, the air passes into the lungs through progessively smaller airways called bronchioles. The lungs contain millions of bronchioles, all leading to alveoli, microscopic sacs where oxygen and carbon dioxide are exchanged.The oxygen rich blood is collected into the pulmonary veins of each lung and is returned via the heart into the systemic circulation.

Systemic circulationThe systemic arteries carry blood via the aorta from the heart to all other parts of the body and return it to the heart via the vena cava inferior and superior. This oxygen rich blood supplies all organs and tissue of the body via the capillaries. There it exchanges the oxygen with carbon dioxide and waste products.

The HeartThe human heart is a muscular pump. The muscle layer that takes care of the contraction of the heart to decrease the size and forces the blood out of its chambers is called myocardium.Normally the size of the heart is a little bit larger than a human fist. It pumps about 8000 litres of blood each day.Reaching the age of 70 years, the number of heart beats will be over 2.5 billion.The heart is divided into two halves, the right and left, by a main septum which extends from the base to the apex.There is no communication between these halves after birth.The right side pumps the blood to the lungs and is less powerful than the left side which is the pump for the systemic circulation that has to drive the oxygen saturated blood to the organs.

The four chambers of the heartRA ( RIGHT ATRIUM )RV ( RIGHT VENTRICLE )LA ( LEFT ATRIUM )LV ( LEFT VENTRICLE )Each half of the heart consists of the two chambers which communicate through a valve.The upper chambers are called atria, the lower chambers are called ventricles.

In total the heart has four valves:The mitral valve is between the left atrium and ventricleThe tricuspid valve is between the right atrium and ventricleThe pulmonary or pulmonic valve is between the right ventricle and the pulmonary artery.The aortic valve is between the left ventricle and the aorta.

The cardiac cycleThe heart beats automatically although it is under the control of the nervous system for it receives innervation from the vagus nerve and the sympathetic nervous system.The pumping action of the heart consists of a contraction or systole and a relaxation or diastole. Both atria contract simultaneously,driving their contents into the relaxed ventricles during ventricular diastole.The ventricles then simultaneously go into systole whereas the atria go into the diastole and blood flows into the atria from the vena cava to be discharged into the ventricles during the next atrial systole.The usual adult rate of the heart is about 70 BPM (beats per minute) but it increases during exercise or excitement and in various abnormal conditions.

The rhythm of the cardiac cycle results from the coordination of the myocardial contractions achieved by special areas in the myocardium. The cardiac impulse starts in the sino-atrial node situated in the wall of the right atrium,it spreads to the atrio-ventricular node and is conducted from this point by the Bundle of His that divides into several bundle branches to all parts of the ventricles.The cardiac cycle is accompanied by electrical changes that can be detected by the electrocardiograph (ECG).

ECGA normal ECG has the following features:P Wave: depolarisation.Atrial contraction begins (Atrial depolarisation)PR interval: Atrial contraction

QRS complex: Ventricular contraction begins (Ventricular depolarisation) ST segment: rapid systolic ejection T Wave: due to ventricular repolarisation (relaxation of ventricular muscle)

Blood pressureThe pulse is the dilatation of an artery caused by the blood pressure increase due to the contraction of the heart. Blood pressure is the pressure exerted by the blood against the vessel wall.The systolic pressure is determined primarily by the rate and volume of ventricular ejection in relation to the arterial elasticity.Systolic pressure is the pressure during contraction of the heart,normally between 100 to 120 mm Mercury (approximately 16 k Pascal).The diastolic pressure is determined by the rate of diastolic pressure drop and the heart rate as it effects the duration of the diastole.Diastolic pressure is the pressure during relaxation of the heart, normally between 65 and 80 mm Mercury(approximately 11 k Pascal)

Pressure measurements

The three principal attributes of circulating blood are flow, volume and pressure. Various methods for measuring cardiac output provide information concerning total blood flow through the heart, but of these three important variables, only blood pressure is routinely measured in patients. Direct pressure measurements have intrinsic value in determining certain conditions under which the circulatory system is functioning.During a coronary angiography several pressures at different catheter positions are measured.

Left heart pressuresThe following graphs give only an indication of the shape of the graph for each different measured pressure. The pressure gives only a rough indication of possible measured values.

Aortic pressureA catheter is guided into the ascending part of the aorta.Example:Systolic pressure: 118 mm HgDiastolic pressure: 57 mm HgMean pressure: 81 mm HgHeart rate: 54 bpm.

Left ventricle pressureA catheter is guided into the left ventricle passing through the aortic valve.Example:Systolic pressure: 166 mm HgEnd diastolic pressure: 32 mm HgHeart rate: 80 bpm.

Left atrium pressureA catheter may be pushed into the left atrium passing through the mitral valve.If there is a mitral stenosis it may not be possible to push the catheter into the left atrium. The Pulmonary Capillary Wedge pressure from the right heart catherisation may substitute the left atrium pressure.Example:Mean: 13 mm HgHeart rate: 82 bpmValue: 18 mm Hg.

Pullback pressureA Catheter is pulled back from the left ventricle into the aorta.Example:left ventricleSystolic pressure: 188 mm HgEnd diastolic pressure: 151mm HgHeart rate: 167 bpmaortaSystolic pressure: 190 mm HgDiastolic pressure:135 mm HgMean pressure: 125 mm HgHeart rate:158 bpm

This pullback method is to make an assessment of the aortic valve and very common during a cardiac procedure. the two pressures are used for the pressure gradient that plays a role in the assessment of valvular stenosis.

Right heart pressuresRight atriumA catheter is guided into the right atrium.Example:Value: 18 mm HgMean: 15 mm HgHeart rate: 89 bpm.

Right ventricleA catheter is guided into the right ventricle passing through the tricuspid valve.Example:Systolic pressure: 42 mm HgEnd diastolic pressure: 8 mm HgHeart rate: 84 bpm.

Pulmonary arteryA catheter is pushed into the pulmonary artery passing through the pulmonary valve.Example:Systolic pressure: 29 mm HgDiastolic pressure: 15 mm HgMean pressure: 21 mm HgHeart rate: 130 bpm.

Pulmonary capillary wedge pressureA catheter is guided into the left or right pulmonary capillary wedge position.Example:Value: 18 mm HgMean: 13 mm HgHeart rate: 77 bpm.

Zero Calibration(For pressure measurements)Before starting a cardiac procedure, a zero calibration is done for each patient. According to an international agreement, the reference level for the pressure measurement system is the pressure on the surface of the right atrium. It can be assumed that the pressure there is identical to atmospheric pressure at the end of expiration. It is therefore crucial before each examination that the membrane of the pressure transducer (Dome) is adjusted to the level of the patients right atrium before setting the zero balance of the pre-amplifier.This reference point is measured using a special tool that divides the patients chest height into 2/5 and 3/5.

Cardiac OutputThe cardiac output is mainly influenced by changes in the stroke volume and the heart rate. (CO = SV x bpm)The cardiac output in healthy adults is between 5 and 8 litres per minute.During a cardiac procedure, the Cardiac Output (CO) is measured using different techniques.

ThermodilutionThe Cardiac Output is measured using a special thermodilution device. A special Pulmonary artery balloon catheter (Swan-Ganz) is used with a thermistor at the tip.The catheter is positioned in the Pulmonary artery. A cold fluid ( usually 10 ml saline for adults) is injected. This cold saline mixes with the blood causing a decrease in blood temperature. This is sensed by the thermistor.The cardiac output is measured by the change in temperature over time.

FickApplied to the lungs, the Fick principle is used to calculate the volume of blood required to transport the oxygen taken up from the alveoli per unit time.This calculation can be done using special hemodynamic software that requires the following input:Haemoglobin (Hb)Venous oxygen saturation (VO2)Oxygen saturation taken from aortaOxygen saturation from pulmonary arteryBody surface area (BSA)WeightHeightSex

Ventriculography

With the help of X-ray images and special software of the system (Ejection Fraction program), the cardiac output can be measured.

Coronary arteriesThere are two main coronary arteries - the left and right.The left coronary artery begins as a main stem called the Left Main Coronary Artery (LMCA) which varies between 1 and 15 mm in length. This artery divides in two major branches, the Left Anterior Descending artery (LAD) and the Circumflex artery (CX).The Right Coronary Artery (RCA) is a single long vessel with smaller side branches.The LAD and CX each supply large areas of heart muscle with blood. The coronary artery tree is categorized into three systems based on the mass of heart muscle which are supplied with oxygen.

The Left Anterior Descending Artery (LAD)

The LAD is a branch that runs on the front of the heart in the groove that demarcates the left and right ventricles. This artery supplies oxygen and nutrients to a large part of the inter-ventricular septum and the front wall of the left ventricle. Obstruction of this artery causes infarction of a large muscular area in the left ventricle and may be fatal.

The Circumflex Artery (CX)

The CX is the other major branch of the LMCA and turns backwards to run along the groove between the left atrium and ventricle.This artery has multiple smaller side branches that supply blood to the left margin of the ventricle. Since this margin is obtusely angled, these branches are also called obtuse marginal (OM) branches, of which there may be a varying number (1-7). These OM branches also supply a considerable area of ventricle muscle, and may cause serious damage if diseased.

The Right Coronary Artery (RCA)The RCA is the other main coronary artery branch arising from the aorta and running in the groove between the right atrium and ventricle. This artery is usually smaller than the LMCA, and supplies a smaller area of heart muscle,mainly the right ventricle. As it curves behind the heart, the RCA has two side branches - the Posterior Descending Artery (PDA) and the Posterior Left Ventricular Branches (PLB). The PDA supplies blood to the posterior portion of the interventricular septum and the PLB supplies a part of the back wall of the left ventricle.

Other important coronary artery branches

While the "big three" are the major branches, some smaller ones may be quite important as well. The sino-atrial node artery supplies the S-A node which is the pacemaker of the heart and sets its rhythm.This branch comes off the RCA in 55% and off the LCA in the other 45%.The atrio-ventricular node artery supplies the A-V node, which is located between the atria and ventricles and controls spread of electrical impulses from the atrium to the ventricle. While in 90% of cases this branch originates from the RCA, in the other 10% it may be a branch of the CX.Damage or blockage of this branch may result in a serious arrhythmia called heart block".

Cardiac procedures

The cath-lab is used for several procedures, the following will give an overview of the most common diagnostic and intervention procedures.

Cardiac catheterisationCardiac catheterisation may be indicated for:

1.Unstable angina 2.Abnormal treadmill test 3.Valvular disease 4.Acute myocardial infarction (heart attack) 5.Cardiomyopathy and/or heart failure

The following information can be obtained from a cardiac catheterisation:

1 Determination of presence of stenoses (narrowing) in the coronary arteries or coronary artery bypass grafts 2 Determination of how well the heart muscle squeezes (contractibility) 3 Evaluation of the heart valves 4 Measurement of various pressures inside the chambers of the heart 5 Determination of presence of any birth defects or shunts

ProcedureCatheters are pushed up in the aorta, usually via the femoral or brachial artery and then into the coronary arteries. Contrast medium is injected to assess blood flow through the artery while various exposures are taken from different angles. Then another catheter,pigtail shaped, is placed into the aorta where pressure measurements are made. This catheter is then advanced across the aortic valve and pressures within the left ventricle are obtained.The catheter is then attached to an injector and contrast medium is injected.Pressure measurements are again taken after injection of contrast medium and as the catheter is withdrawn back across the aortic valve and then removed.

ProjectionsTo visualise the coronary arteries several projections are necessary. When mentioning the various projections, remember that L.A.O. rotation indicates that the Image Intensifier is rotated to the left side of the patient. R.A.O. rotation indicates that the Image Intensifier is rotated to the right side of the patient. Using cranial angulation the Image Intensifier angulates to the patients head while using the caudal angulation the Image Intensifier angulates towards the patients feet.

To recognize the different vessels one can think of the following hints:

- The Circumflex lies closest to the spine- Only the LAD (Left Artery Descendens) reaches the apex- In L.A.O. position, the apex points to the left- In L.A.O. position, the LAD lies to the left- In L.A.O. position, the spine is on the right- In R.A.O. position, the spine is on the left- In R.A.O. position, the apex points to the right.- In L.A.O. position, the RCA (Right Coronary Artery) resembles a C.

Left Coronary arteriesR.A.O. 30oThe Right Anterior Oblique R.A.O. projection at 30o permits the entire circumflex system to be studies as well as the first centimetres of the anterior inter ventricular artery.

Left Coronary artery R.A.O. 30o

Left Coronary arteriesL.A.O. 55/60oThe Left Anterior Oblique (L.A.O.) projection at 55/60o mainly studies the diagonal arteries and the mid and distal parts of the LAD. On the other hand the circumflex is not well defined.

Left Coronary artery L.A.O. 55/60o

Left Coronary artery L.A.O. 55/60o

Left Coronary arteriesL.A.0. 55/60o + 20o cranial projectionThe cranial angulation of 20o combined with the L.A.O. projection at 55/60o is especially useful to study the left main coronary artery.

Left Coronary artery L.A.0. 55/60o + 20o cranial

Left Coronary arteriesLeft Lateral projectionThe left lateral projection, allows the study of the different segments of the anterior inter ventricular artery, the first diagonal artery and the left marginal artery.

Left Coronary artery in Left Lateral

Right Coronary arteryLeft lateral projectionThis projection permits the study of the second (vertical segment of the right coronay artery and the collateral branches (conus branch, right ventricular artery, right marginal artery)

Right Coronary artery in Left lateral

Right Coronary arteryL.A.O. 45o + 15o caudal angulationThis projection allow the whole study of the R.C.A. and clearly defines the region of the crux of the heart.

Right Coronary artery in L.A.O. 45o + 15o caudal

Right Coronary arteryR.A.O. at 45oThe Right Anterior Oblique (R.A.O.) projection at 45o permits the survey of the second (vertical) segment of the right coronary artery, the posterior inter ventricular artery and the collateral branches (right ventricular and right marginal arteries).

Right Coronary artery in R.A.O. 45o

Left ventricle angiogramTo measure various pressures and to visualize how well the left ventricle contracts, a pigtail shaped catheter is used. This catheter has several side holes to make it possible to inject contrast using a high flow rate.The left ventricle can be divided into several areas to determine which part of the ventricle muscle is not functioning properly.The projection most used to visualise the left ventricle is RAO 30o

Optimize image quality

The patients treatment depends on the diagnosis. Therefore the image quality plays a major role. To obtain the best image quality, the following factors have to be taken into account.

ShuttersShutters are built in the system to adjust the field of view and to avoid showing white margins at the edges of the image that might interfere with the perception of image detail. Be aware that if the field of view is set too small, there is a risk to miss some of the anatomy.

Wegde filtersTo prevent distracting highlights in the region of interest (lung tissue) that will affect image quality, wedge filters can be used.

ProtocolImage quality is also determined by the protocol selected. Within each protocol several parameters are optimised for a certain exposure technique or projection. It is therefore of utmost importance to select the correct protocol before starting a diagnostic exposure run.

Image Intensifier positionThe image intensifier is moved away from the patient in preparation of the next projection using a different rotation and or angulation. To avoid air gaps that deteriorate image quality, the distance between the image intensifier and the patient should be minimized every time again after change in projection view.

Patient communicationA good patient communication will reduce patient physical or respiratory movement during image acquisition.

Catheter positionWhen starting an image acquisition, the best image quality is achieved when the whole anatomy of the coronary arteries is visible without having to move the table.This is possible when having the catheter tip positioned correctly within a certain area of the field of view on the monitor.

To give an indication of the position of the catheter tip for each projection, the field of view is divided into 9 zones.If the tip is within the zone 1,2,3 or 5, then in most of the acquired runs the whole anatomy of the coronary arteries will be within the field of view without having to move the table. Examples:

To give an indication of the position of the catheter tip for each projection, the field of view is divided into 9 zones.If the tip is within the zone 1,2,3 or 5, then in most of the acquired runs the whole anatomy of the coronary arteries will be within the field of view without having to move the table. Examples:

Left coronary arterty and Circumflex

Left coronary arterty and Circumflex

Right coronary artery

InterventionsPTCAPercutaneous Transluminal Coronary Angioplasty (PTCA) is a procedure to attempt to open up a narrowed artery by using a catheter that has a balloon at the tip of it. When the balloon is inflated, the pressure flattens the plaque against the walls of the artery which will then improve the blood flow to the heart.

ProcedureThe balloon catheter has a radiopaque marker in the middle portion of the balloon. Note that there are also balloon catheters with proximal and distal markers.The central marker is placed in the middle of the coronary artery stenosis. The balloon is then slowly inflated with a small hand-held pump that is filled with contrast. The balloon is inflated until there is no dent in the balloon. The balloon is left inflated anywhere from one to two minutes depending on the individual case and watched under fluoroscopy. Several inflations may be necessary to achieve the desired reduction of the stenosis.

Stent placementStent placement is a procedure that often follows the PTCA. Once the narrowed artery is opened, a stent reduces the likelihood that the artery will narrow again. Coronary stents are stainless steel frames attached to a special designed balloon catheter. The stent is expanded by inflating the balloon. Once the stent is expanded succesfully the balloon is deflated. The stent itself is designed in such a way that it remains it shape after deflating the balloon.Drug eluting stents reduce the risk of re-stenosis.

Other ways of reducing a coronary blockage

Instead of using a balloon there are other devices to increase the lumen of the coronary arteries:

AngiojetAn angiojet can be used to widen a coronary artery that is narrowed due to a fresh thrombus. This high pressure jet creates a low pressure region within the blood vessel and the whole system acts like a vacuum cleaner and sucks up the fresh thrombus.

Atherectomy

Used on hard plaque which a balloon is unable to compress. A special atherectomy catheter has a small knife to shave off the plaque. The catheter consists of a shaft on which a balloon is mounted on one side, on the side opposite the balloon there is an opening in the shaft, which allows the blade to protrude. The catheter is positioned with the opening over the plaque and the balloon inflated to hold the catheter in place. The blade is then moved back and forth across the plaque, the shavings are sucked back via the catheter. Once the plaque has been de-bulked, the normal PTCA procedure or stent placement will follow.

RotablatorThe rotablator is primarily used for concentric hard plaque and calcified lesions. It uses a diamond powder coated tip on a catheter at high speed 80.000 to 150.000 rpm) to de-bulk the lesion prior to PTCA procedure and stent placement.

Electrophysiology (EP)Reason for an Electrophysiology study (EP) is arrhythmia, or abnormal heart rhythm

EP mapping procedure.Pacing wires are positioned in various areas in the heart. These wires are connected to a large computer, which allows specific measurements of all parts of the hearts electrical system. This test takes approximately 1 to 3 hours to complete. If the arrhythmia is reproduced the arrhythmia may terminate itself, or an electrical shock, delivered through adhesive patches on the chest and back may return the rhythm to normal.

AblationCatheter ablation is a technique to eliminate alternate pathways present in the heart causing arrhythmias (abnormal heartbeats) that interfere with the normal conduction.

ProcedureOnce the area of the heart has been defined through catheter mapping, a special ablation catheter is placed at the site of the abnormal pathway.Radiofrequency waves are delivered through this catheter. The heat formed by this catheter causes scar tissue on this pathway of cells so that the abnormal conduction cannot pass through.

PacemakerPacemaker implantation is done on patients with severe heart rhythm disturbances. If the SA node sends impulses out too slowly, it results in a rhythm that is too slow. This is called "Sick Sinus Syndrome". Another situation may result from impulses being blocked at some point along the electrical pathway in the heart. This is called heart block, and can also result in a rhythm which is too slow.

ProcedureAn incision is made, and the pacemaker lead is placed through the subclavian vein which leads directly to the right side of the heart. A small pocket is then made in the upper chest area and the pacemaker generator is placed. The lead will be connected to the generator, checked and programmed. The incision is then closed.

IABPThe Intra-Aortic Balloon Pump (IABP) is a mechanical device to reduce the workload of the heart and to improve blood flow to the coronary arteries.The pump consists of a balloon attached to the end of a catheter. The balloon sits in the aorta and opens and closes in response to the hearts contractions. After the heart contracts and propels oxygen-rich blood into the aorta, the balloon rapidly opens up and propels some of the oxygen-rich blood back toward the coronary arteries. Just before the hearts next contraction, the balloon rapidly deflates creating a lower pressure in the aorta so the heart does not have to work as hard to pump the blood out.

Basic pathology of the heart

Arteriosclerotic coronary diseaseIn all blood vessels of all people some fatty material starts to build up on the inside of the blood vessel walls. In some people the rate of deposit of fatty material is faster than in others resulting in atherosclerose or arteriosclerosis.Although the terms are used interchangeably, atherosclerose is a type of arteriosclerosis that is characterised by deposits of plaque.Arteriosclerosis is particularly dangerous when the vessel that is involved is a coronary artery and the lumen is narrowed by 50 to 70% of its normal diameter.Arteriosclerosis can lead to angina pectoris, heart attack or myocardial infarction.

Valvular diseasesThe heart has four valves. Any of these valves may fail to function properly,but most commonly the valves on the left side of the heart are affected. The valves may narrow, called stenosis, or may close incorrectly, called prolapse.

Aortic valve stenosisAortic valve stenosis results in having the left ventricle to work harder to push out the blood. As this occurs the muscular walls of the ventricle thicken.

Aortic regurgitationWhen the aortic valve fails to close completely after the heart has pumped out the blood into the aorta, blood leaks back into the left ventricle. This may be the result of an endocarditis (infection) or heart attack. It may leave the valve scarred resulting in improper functioning of the valve.

Mitral stenosisA mitral stenosis results in an increase of pressure in the left atrium leading to an elevation of the pressure in the lungs.

Mitral regurgitationImproper closure of the mitral valve causes blood to leak from the left ventricle back into the left atrium. This may be the result of an endocarditis (infection) or heart attack. It may leave the valve scarred resulting in improper functioning of the valve.

Congenital diseasesValve damage is not the only congenital condition that can damage the heart.Other forms of congenital heart disease include holes in the septum that allow the blood to leak or flow directly from one chamber into another,rather than flowing in the proper direction through the valves.

Left-to-right shuntPart of the blood flow goes directly from the left side of the heart to the right side of the heart. The hole can either be between the atria or between the ventricles.The patent hole (foramen ovale) between the atria is called the Atrial-Septal-defect.The hole between the ventricles is called the Ventricular-Septal -defect

Patent ductus BotalliIf the communication between the aorta and the pulmonary veins remains after birth, de-oxygenated blood mixes with the systemic circulation.

Coarctation of the aortaThis is a narrowing (stenosis) in the proximal descending part of the aorta. The aortic valves are usually narrower than normal.

THANK YOU

Left Coronary artery L.A.O. 55/60o