cardiac scintigraphy

what are the two main functions of the ECG?

1. to clarify disturbances of the heart rhythm

   • is the heart rate slow or fast?

   • what is the rhythm of the heart rate?

   • what are the side effects of medications they’re on, or whatever event is affecting their heart?

2. detect abnormalities in myocardium

   • congenital, myocardial infarction (heart attack), acute coronary syndrome (angina), heart failure, ventricular hypertrophy

what is the imaging protocol for GCBP first pass study evaluating RVEF?

• inject small volume of Tc-99m RBC or Tc-99m Pertechnetate as rapid bolus

• Data acquisition is started just before bolus injection and stopped after the transit of the bolus through the heart.

• 16 to 24 frames (per R-R interval), 64x64 matrix, 60 seconds (over 5 to 10 cardiac cycles)

• Proceed with standard equilibrium GCBP imaging for LV function and wall motion analysis

what is the camera positioning for GCBP first pass study evaluating RVEF?

right anterior oblique RAO ~30 degrees

FOV sternal notch to left and right costal margins

is the ECG a reliable stand-alone examination?

no, the ECG is only one method of examining the heart and only has value when considered along with a full history and clinical examination. It cannot ever overtake a clinical examination

the ECG presents electrical activity only, not actual pumping of the heart

what ways can the heart be examined? (8)

1. auscultation (stethoscope)

2. chest x-ray (assessing heart size)

3. CT

4. MRI

5. echocardiogram (ultrasound, assessing valves, ejection fraction, pumping mechanism)

6. angiogram

7. open heart surgery (last resort)

8. ECG

why is a 12 lead ECG called ‘12 lead’?

the 12 lead ECG has 10 leads/wires that can produce 12 different angles/views of electrical activity within heart from different areas

12 angles of electrical activity

what is infarction?

extreme lack of oxygen leading to cell death

• characterised by fixed hypoperfusion defect on both rest and stress images

  • indicating an irreversible defect

• previously functioning muscle is replaced by granulation tissue and non contractile fibrous scar tissue

• can result in insufficient cardiac output, so the left ventricular ejection fraction should be reviewed, the patient should be managed by cardiology (urgency based on left ventricular ejection fraction) to minimise risk of heart failure

how are the 12 ECG views categorised?

12 leads (views) can be divided into 2 groups of 6

1. limb leads = 3x bipolar, 3x unipolar

2. precordial/chest leads x6, all unipolar

what is the difference between unipolar and bipolar ECG leads?

bipolar leads needs two electrodes, one positive and one negative, which shows the electrical potential between 2 electrodes

unipolar leads have one electrode with a positive pole, the negative pole is computed by the ECG machine

how are the limb leads placed for a 12 lead ECG, and what views do they generate?

the 6 limb leads (views) are generated by 4 electrodes - RA, LA, RL, LL

they generate views I, II, III, aVr, aVL, aVF, giving a 2D view of the heart’s frontal plane

consider patient amputations/bandages/cannula at placement point

place electrodes on fatty areas, avoid major muscles or bone

keep placement consistent for future ECG scans, document placement, do not allow for variation

if patient has tremors, shaking will affect peripheral placements, prefer central positioning

do not mix central and peripheral placement between arms and legs → consistency

how are the chest leads placed for a 12 lead ECG, and what views do they generate?

the 6 chest (precordial) leads (views) are generated by 6 electrodes - V1, V2, V3, V4, V5, V6

leads give view of heart’s horizontal plane

V1 - 4th intercostal space to right of sternum

V2 - 4th intercostal space to left of sternum

V3 - between leads V2 and V4

V4 - 5th intercostal space at midclavicular line

V5 - level with V4 at left anterior axillary line

V6 - level with V5 at left midaxillary line (directly under midpoint of armpit)

what are the leads of the ECG oriented towards?

I, III, aVF to the inferior surface of the heart

I, aVL to the lateral wall of the heart

V1, V2, V3 to the anteroseptal surface of the heart

V3, V4 to the anterior surface of the heart

V4, V5, V6 to the anterolateral surface of the heart

how are leads interpreted on an ECG scan?

I is upright deflections, including P, QRS, T

II is upright with most prominent P waves, repeated for the entirety of the paper

III usually upright but can have large variations

aVR normally totally upside down, aVR has low voltage

aVL looks like I but with lower voltage

aVF is similar to II or III or may be in between

how should the patient be positioned during an ECG?

supine ideally

if patient is SOB or cannot lie flat, semi fowlers position is second to ideal

go as low as possible as tolerated by patient, potentially high fowlers

comment position used and why positioned was used (shortness of breath, comfort and safety)

during semi/high fowlers, pillows not recommended

pillows are ok if in supine

the higher the patient, the less recommended pillows are

how should the patient be prepared before an ECG?

• consent

• consider males/females patient/practitioner

• ensure privacy and a warm environment to avoid shivering

• assure no electricity being administered, harmless procedure

• time frame approximately 5 minutes

• advise to breathe normally

• shave/clean skin if required, obtain consent

what are the indications for performing an ECG? (7)

1. looking for chest pain causes

2. evaluating problems that may be heart related (tiredness, SOB, dizziness, fainting)

3. identifying irregular heart beats

4. Assessing heart health before procedures/surgery/treatment

5. assessing implanted pacemaker

6. determining if heart medicines are working

7. baseline tracking of heart’s function during exam for future comparison

what are common errors that occur in ECG? (3)

1. reversing electrodes/poor electrodes

2. continuing procedure while patient is agitated or anxious, SOB

3. placing electrodes over unsuitable positions (bone, muscle, metal)

how do we assess the patient before/during an ECG?

• check colour, skin - warm, dry, damp, clammy

• can you feel their pulse?

• are they having chest pain?

• do they have SOB?

• determine if they have stable/unstable rhythm

• consider patient type

  • athletes may normally have low heart rate

  • patient may have medication reducing heart rate

  • patient may have require immediate pacemaker insertion if accompanied by chest pain, shortness of breath, and ECG interpretation of someone in heart block

how can heart rate be calculated reading an ECG?

6 second method

select 6 seconds of ECG (30 big boxes) and count the number of R waves that appear - multiply by 10

method can be used on both regular and irregular rhythms

what’s the difference between monophasic and biphasic defibrillators?

monophasic defibrillators deliver energy in one direction, rarely used today, not as effective

biphasic defibrillators deliver energy in two directions, requires fewer Joules of electricity than monophasic, providing the same effect → fewer post shock abnormalities than monophasic defibrillators

what is a sinus rhythm (SR)?

• regular rhythm

• normal rate 60-100bpm

  • coming through SA node

• may hear normal sinus rhythm NSR

• management: usually observation only

what is a sinus bradycardia?

• through SA node, but slower than normal

• rate <60bpm

• regularly spaced apart and hills and spikes are clear - sinus

• patients can be asymptomatic (athlete) or symptomatic

• mild 45-59bpm - probably asymptomatic

• 30-45bpm - S&S of haemodynamic compromise, syncope, weakness, dizziness, chest pain, cool clammy skin

what is the management for sinus bradycardia?

• doesn’t usually require treatment unless accompanied by a rate that causes haemodynamic compromise

• if asymptomatic, none required

• if symptomatic, make quick decisions as to if they’re stable or unstable

  • if unstable, activate MET call, apply oxygen, take blood pressure

• if symptomatic due to bradycardia Atropine may be indicated

  • found on drug arrest trolley

what is a sinus tachycardia?

• 100bpm

• rate related, patients can be asymptomatic or symptomatic

• decrease in cardiac output, especially those with CAD

• chest discomfort, dizziness, shortness of breath, light headedness, palpitations, syncope

what is the management for sinus tachycardia?

• assess client, are they symptomatic, stable?

• oxygen if indicated (low oxygen saturation)

• monitor BP and heart rate

• obtain IV access

• treat cause if able

  • pain, fever, anxiety

• notify doctor if persistent or symptomatic, or meets pre MET/MET criteria

• potentially beta adrenergic blockers to slow HR

what is atrial fibrillation?

• P wave will be absent, replaced by fine fibrillatory waves

• one or more rapidly firing sites in atria, or entry involving one or more circuits in atria, is at a much higher rate

  • usually 4-600bpm

• SA node is not firing how it should be

• rate related

• S&S of decreased cardiac output

• light headedness, palpitations, dyspnoea, chest discomfort, low BP

• at risk for clot formation

• slow AF may indicate medication toxicity

what is the management for atrial fibrillation?

• assess client, are they symptomatic, stable?

• oxygen prn

• monitor BP and heart rate

• obtain IV access

• bed rest prn

• notify doctor if persistent or symptomatic, or meets pre MET/MET criteria

• Potential medical management

  • treatment depends on level of haemodynamic compromise, ventricular rate and duration of rhythm

  • synchronised electrical cardioversion is used when prompt rate reduction is needed

  • Digoxin and other antiarrhythmic drugs for rate control

  • radiofrequency catheter ablation

  • anticoagulation if in rhythm for greater than 48 hours

what is ventricular tachycardia?

• rhythm is regular, between 100-200bpm

• the P wave is absent and QRS complex is wide and bizarre

• can be conscious or unconscious in VT, check patient

what is the management for ventricular tachycardia?

• assess client, are they symptomatic, stable?

• if has pulse: oxygen, bed rest, IV access, call MET call or if unstable call MET and Dr, monitor closely

• if pulseless/unstable, call CODE BLUE, ABCs, CPR, IV access

• Potential medical management

  • treat underlying cause

    • IV mag sulfate or potassium to correct imbalances, assess medications

  • stable symptomatic patients - oxygen and IV anti-arrhythmics to suppress rhythm amiodarone)

  • unstable patients - oxygen and synchronised cardioversion

  • pulseless - CPR and defibrillation

  • ALS guidelines

  • implantable cardioverter defibrillator ICD, ablation

what is ventricular fibrillation?

• no cardiac output, no peripheral pulses, no BP, loss of consciousness

• the height of VT is the defining point compared to VF

• death imminent if untreated

• coarse VF indicates a more recent onset and more likely to be reversed by defibrillation

• causes most cases of sudden cardiac death outside a hospital

what is the management for ventricular fibrillation?

• Immediate action

  • medical emergency CODE BLUE, speedy response essential

  • potential survival is a matter of minutes

  • very poor prognosis

• Essential management

  • assess client

  • call code, ABC, CPR

  • IV access

• Potential medical management

  • defibrillation, CPR

  • ALS guidelines

what is asystole?

• ventricular standstill, no electrical activity, no cardiac output

• most often seen following cardiac arrest with ineffective resuscitation

• causes

  • M - MI

  • A - acidosis

  • T - tension pneumothorax

  • C - cardiac tamponade

  • H x5 - hyper/hypokalaemia, hypotension, hypoxia, hypovolaemia

  • E - embolus (pulmonary)

  • D - drugs or drug overdose

• not shockable rhythm - no electrical activity present

what are red blood cells?

• aka erythrocytes, very small, circular, biconcave, highly flexible

• makes up around 44% of blood

• carries oxygen around body

• made in bone marrow, starting as immature cells starting as HSC stem cells which can branch into RBC, WBC or platelet

• after ~7 days of maturation they are released into bloodstream

• survive ~120 days, they are damaged as they move through smaller blood vessels

• have no nucleus (little oxygen required) and can easily change shape to fit through blood vessels

• contains haemoglobin protein, which has components called hemes, which bind iron (Fe2+) which bind oxygen

what does the cardiovascular system include? (3)

• heart

• blood

• blood vessels

describe the heart size and location

• heart is relatively small, roughly same size as a closed fist

  • 12cm long, 9cm wide at its broadest point, 6cm thick

• heart rests on diaphragm, near midline of thoracic cavity

  • 2/3 of hearts mass extends to the left of body’s midline

• heart is surrounded by pericardium membrane, offering protection

  • pericardium confines heart to its position in the mediastinum

    • allows sufficient freedom of movement for vigorous and rapid contractions → required to sufficiently pump blood through body

what are the three layers of the wall of the heart?

1. epicardium

2. myocardium

3. endocardium

what is the epicardium of the heart wall?

• outermost layer

• houses major coronary and cardiac vessels of the heart

what is the myocardium of the heart wall?

• middle layer

• composed of cardiac muscle tissue

• responsible for pumping action of the heart

• includes interventricular septum partition, which separates left and right side of heart

what is the endocardium of the heart wall?

• innermost layer

• endocardium is smooth inner lining that minimises surface friction as blood passes through heart

what are the four valves of the heart?

1. mitral

2. tricuspid

3. aortic

4. pulmonary

what is the purpose of the valves of the heart?

• help regulate blood flow through heart chambers

  • ensures blood flows in correct direction and prevents backflow

where is the mitral valve of the heart?

between the left atrium and left ventricle, aka bicuspid valve

where is the tricuspid valve of the heart?

between the right atrium and right ventricle

where is the aortic valve of the heart?

before the between the left ventricle and aorta

where is the pulmonary valve of the heart?

between right ventricle and pulmonary arteries

what are the distinct walls of the myocardium? (5)

1. anterior

2. lateral

3. inferior

4. posterior

5. septal

what blood does the right atrium receive and from where? (3)

deoxygenated blood

1. superior vena cava (upper body)

2. inferior vena cava (lower body)

3. coronary sinus (from heart’s muscular tissue)

what blood does the left atrium receive and from where?

oxygenated blood

via pulmonary veins

which ventricle has thicker myocardium?

left ventricle, it must generate enough force to overcome the resistance of systemic circulation to pump blood throughout entire body

what is the blood flow process through the heart?

1. deoxygenated blood collects in right atrium, it passes through tricuspid valve into right ventricle

2. right ventricle pumps blood via the pulmonary valve

3. blood enters the pulmonary trunk, dividing into pulmonary arteries, which carry deoxygenated blood to lungs

4. pulmonary arteries divide into pulmonary capillaries, where blood loses carbon dioxide and gains oxygen

5. blood is oxygenated and re enters heart via pulmonary veins

6. pulmonary veins deposit blood into left atrium

7. blood enters left ventricle via bicuspid valve

8. left ventricle pumps oxygenated blood into body via aorta and systemic arteries, after passing through the aortic valve

9. blood enters systemic circulation, and blood loses O2 and gains CO2

• some blood from aorta flows into coronary arteries, supplying oxygenated blood to heart muscle

10. deoxygenated blood enters right atrium from

• superior vena cava (upper body)

• inferior vena cava (lower body)

• coronary sinus (from heart’s own muscular tissue)

what is the coronary circulation and what are the main coronary arteries?

coronary arteries branch from ascending aorta and encircle the heart, where the main coronary arteries are

1. right coronary artery

2. left coronary artery → left anterior descending artery

   3. left circumflex branch artery

what are cardiomyocytes?

muscle cells of the heart, aka cardiac muscle fibres

• high in mitochondria

• enables rapid transmission of electrical signals throughout heart and ensures contractions occur simultaneously across muscle

• have ability to generate spontaneous electrical impulses that initiate heartbeats

how are heartbeats initiated by cardiomyocytes?

1. when impulses occur, sodium channels open allowing sodium ions to flow into cells, leading to depolarisation - cell becomes more positive

2. during depolarisation, calcium channels open allowing calcium ions to enter cells, triggering muscle contraction

3. after contraction, calcium ions are pumped out of cells or stored within cells by specific calcium pumps

4. sodium potassium pumps restore ionic balance by removing 3 sodium ions for every 2 potassium ions entering - cell is prepared for relaxation and next contraction cycle

what does the cardiac intrinsic electrical conduction system include of? (4)

1. sinoatrial SA node

2. atrioventricular AV node

3. bundle of His

4. Purkinje fibres

where is the sinoatrial node located?

in the right atrial wall

where is the atrioventricular node located?

in the atrial septum

where are the Purkinje fibres located?

in the ventricular myocardium

where is the bundle of His located?

between the AV node and the ventricles, connecting the AV node to the right and left bundle branches

how does the cardiac intrinsic electrical conduction system cause the cardiac cycle?

1. specialised cardiomyocytes (pacemaker cells) in the SA node initiate the electrical impulse, causing atrial contraction

2. the impulse reaches the AV node, which delays the impulse to ensure atria fully contract before transmitting signal to the ventricles

3. impulse moves down Bundle of His to the Purkinje fibres - Bundle of His transmits impulse from AV node to ventricles

4. Purkinje fibres distributes impulse through ventricles, ensuring coordinated contraction

5. all sections of the ventricular walls move inward symmetrically

what occurs during systole?

ventricles contract, pushing blood from left ventricle into aorta, and from right ventricle into pulmonary artery

what occurs during diastole?

ventricles dilate, pulling blood into ventricles as atria contract

what does the P wave represent on the ECG?

atrial depolarisation

what does the QRS complex represent on the ECG?

ventricular depolarisation

what does the R peak represent on the ECG?

the moment when the electrical impulse causes the ventricles to depolarise, leading to contraction

what does the ST segment and T wave represent on the ECG?

the ventricular muscle returning to resting state (ventricular repolarisation)

what does the QT interval represent on the ECG?

the time from the start of ventricular stimulation (ventricular depolarisation) until the completion of ventricular relaxation (ventricular repolarisation)

what does the PR interval represent on the ECG?

represents time from start of atrial stimulation to start of ventricular stimulation

what is cardiac output, and how is it calculated?

the volume of blood ejected from each ventricle per minute

stroke volume x heart rate

what is stroke volume, and how is it calculated?

the amount of blood ejected from the ventricle during each contraction

end diastolic volume - end systolic volume

what is cardiac ejection fraction, and how is it calculated?

the percentage of blood that is ejected from the ventricle with each contraction, relative to the end diastolic volume

((end diastolic volume - end systolic volume) / end diastolic volume) x 100

what is the purpose of measuring cardiac ejection fraction?

ejection fraction is used to evaluate the heart’s efficiency, and is a critical measure in diagnosing and assessing severity of heart disease

what is the normal ejection fraction range for the left and right ventricle?

for the right ventricle, the normal ejection fraction ranges from 45-60%

for the left ventricle, the normal ejection fraction ranges from 50-70%

what can cardiac ejection fractions over 70% indicate?

• ejection fractions above 70% can indicate a very healthy heart, but they can also be associated with conditions like hypertrophic cardiomyopathy

  • thickening of the heart muscle, reducing the overall size of the ventricle

    • results in a normal ejection fraction, but less blood being pumped throughout overall

what occurs in dilated cardiomyopathy and what are its causes?

• cardiac chambers enlarge and the walls thin

• reducing heart’s efficiency

• causes can vary

  • genetic factors

  • infections

  • alcohol abuse

  • exposure to certain toxic substances

    • ie. chemotherapy

  • cause can remain idiopathic or unknown

what occurs hypertrophic cardiomyopathy and what are its causes?

• heart muscle thickens abnormally

• often due to genetic mutations

• can lead to obstructed blood flow and potentially dangerous arrhythmias

what occurs in left ventricular hypertrophy and what are its causes?

• impact heart’s ability to effectively circulate blood

• thickening of left ventricular wall

• commonly caused by high blood pressure (hypertension), or aortic stenosis

  • causes increased workload on heart, prompting it to thicken the muscle fibres in an attempt to generate more force

what occurs in cardiotoxicity and what are its causes?

• commonly results from exposure to certain drugs or toxins

• cardiotoxicity can lead to arrhythmias, decreased contraction strength and cardiomyopathy

what causes chemotherapy induced cardiotoxicity?

• chemotherapy drugs are designed to kill rapidly dividing cancer cells

  • can also impact healthy cells, including those in the heart

  • includes anthracyclines and HER-2 inhibitors including Herceptin

    • anthracyclines are chemotherapy drugs which can cause cardiotoxic effects

    • HER-2 inhibitors are monoclonal antibodies targeting HER-2 receptors, often overexpressed in breast cancer

      • HER-2 receptors are also present in cardiac muscle cells leading to potential heart damage

what is akinesis of the heart?

complete lack of movement in affected heart regions

what is hypokinesis of the heart?

reduced movement, resulting in weaker contractions

what is dyskinesis of the heart?

abnormal movement resulting in uncoordinated contractions

what is heart failure?

occurs when the heart muscle is unable to pump blood effectively to the rest of the body, resulting from an underlying issue

• often the end stage of many cardiac diseases

what is gated cardiac blood pool imaging?

• Nuclear Medicine Gated Cardiac Blood Pool imaging is a simple and relatively non invasive procedure offering precise LVEF measurements

  • provides standardised results and reproducible measurements, making it reliable for serial imaging

  • quantification of LVEF through gated cardiac blood pool imaging does not rely on mathematical assumptions

    • left ventricular emitted counts are proportional to its volume

  • it can assess cardiac anatomy by overserving blood flow through the chambers, evaluate regional wall motion and quantify right ventricular ejection fraction

what is the radiopharmaceutical used for gated cardiac blood pool imaging?

99mTc pertechnetate radiolabelled to red blood cells

what is gated cardiac blood pool imaging used to assess?

• cardiac failure and myopathy

  • left ventricular ejection fraction and cardiac wall motion

• cardiotoxicity

  • assessing left ventricle capability during chemotherapy

  • diagnosing cardiotoxicity

  • measuring base line left ventricular function prior to interventions with cardiotoxic effects

• less common/rare

  • right ventricular function

  • qualitative analysis of cardiac anatomy

    • looking at blood flow through heart

  • quantifying left to right cardiac shunts

  • achieved using first pass imaging

    • using a rapid bolus

how is Tc99m pertechnetate radiolabelled to RBCs?

1. Tc99m pertechnetate is in a +7 valence state and is unreactive, using reducing agent stannous ions to make Tc99m have a +4 valence state - stannous ions cross the RBC membrane

2. Tc99m pertechnetate is administered, diffuses into RBC and is reduced by stannous, binds strongly and no longer diffuses out of the cell

what are the preferred RBC labelling methods for GCBP?

in vivo and in vivtro

what are the pros and cons of in vivo red blood cell labelling?

• no blood handling, no specialised laboratory equipment required, minimal labour

• lowest labelling efficiency 60-70%

  • still satisfactory for GCBP imaging

what are the pros and cons of in vivtro red blood cell labelling?

• minimal blood handling, no specialised equipment required, minimal cost with minor increase in labour

• combines simplicity of in body processing with slight external intervention, improving reliability of diagnostic imaging will maintaining manageable logistics and reduced blood borne pathogen risk compared to full in vitro techniques

• higher labelling efficiency (80-90%)

  • ideal for GCBP imaging

• administering Tc99m pertechnetate outside body does not travel to other organs - stomach, thyroid, GIT

what patient history is needed for GCBP imaging?

• cardiac history

  • congenital heart disease

  • past or recent myocardial infarction

  • cardiac arrhythmias

  • medications

  • surgeries

  • cardiac risk factors

• cancer history and related treatments

  • highlights risk for potential cardiotoxic effects

what is gating?

• gating is taking snapshots of the heart at specific points in its beating cycle

  • create a clear picture of how it moves and functions

  • helps in understanding the heart’s performance more accurately

• imaging system is set up to recognise the R wave as a trigger point in the cardiac cycle

  • divides the cycle into multiple phases

    • 16-24 between 2 R waves

      • known as the R-R interval

• phases are called bins or frames

• images are captured at each phase

  • triggered by R wave

  • process is repeated over several cardiac cycles to ensure sufficient data collection

• acquired images are sorted and reconstructed based on phase in cardiac cycle

  • generating dynamic sequence that illustrates heart function throughout entire cycle

what is a beat histogram?

• window is set based on the patient’s R-R interval

• window setting represents the variation in heart rate deemed to be acceptable

• window width is commonly set at approximately 20%

  • the range extends 10% above and 10% below the central point/average heartbeat

  • any beats outside the range will be rejected

• window can be adjusted

  • often increased for patients with arrhythmias

  • as the window percentage increases, a greater number of irregular beats are accepted within the R-R interval

    • negatively affecting accuracy of ventricular ejection fraction

    • irregular beats result in images being captured at different points in the cycle

      • leading to motion artifacts that impact the clarity and diagnostic quality of the image

what is the radiopharmaceutical dose used for equilibrium GCBP planar imaging?

500-1000MBq

what is the camera positioning for a GCBP left ventricular ejection fraction image?

30-45 degrees left anterior oblique view

• angle should be adjusted for complete septal separation of left and right ventricle

  • we need to isolate the left ventricle for accurate quantification of left ventricular ejection fraction

• record angle for future studies

what is the camera positioning for a GCBP wall motion assessment image?

left anterior oblique, anterior and left lateral

• left lateral might be acquired with patient in supine position at 90 degree camera angle

• or patient may be in left lateral decubitus position (on side) at 0 degree camera angle

  • said to reduce spleen and diaphragm interference

what are the imaging parameters for GCBP imaging?

• all images are acquired using 16-24 gates with each frame set to collect approximately 250K counts per gate- 8-10 minutes

• zoom of 2.0-2.5 and a matrix of 64x64 used for all images

quantitative vs qualitative GCBP imaging?

quantitative LVEF and wall motion imaging

qualitative wall motion imaging

what does the GCBP time activity curve look like?

• illustrating changes in left ventricular volume throughout cardiac cycle

• curve enables precise calculation of left ventricular ejection fraction

• peak of curve represents end of diastole

  • ventricle at maximum volume

• as heart contracts, curve falls, indicating end of systole when ventricles pump out blood

  • ventricles contain least volume

• as curve rises, it signifies heart relaxing

  • blood flows back into left ventricle

  • small upward bump occurs → atrial kick

    • atria contract to push additional blood into ventricle

      • ensures they are fully filled

• curve reaches peak, marking end of diastole when ventricle is back to maximum volume

• rise and fall reflects heart rhythm

  • atrial kick provides essential boost to ventricular filling before next contraction

what are the left ventricular ejection fraction results?

• normal ejection fraction ranges 50-70%

• severely reduced ejection fraction <30%

• moderately reduced 30-40%

• mildly reduced 41-50%

• normal borderline 50-54%

• healthy range 55-70%

when should a single LAO image be taken during GCBP imaging?

• patients with no known heart disease

• when an LAO image is taken and the LVEF is greater than 55%