STRESS ECHOCARDIOGRAPHY

Dr. Muhammad Mobarock HossainMBBS(CU), MD (card) phase BUniversity cardiac centre, BSMMUDHAKA, BANGLADESH.Contact: +8801914007246Email: mobarockdr@gmail.com

History

History :

The Krannert Institute and Indiana University introduced the technique of dobutamine stress echocardiography in the United States over 17 years ago.

Link: http://medicine.iupui.edu/krannert/programs/echo/dobutamine/

Cont…

Cardiac ultrasound is used to image the function of the heart and Medicines (dobutamine or dopamine) are used to

stress the heart.

Cardiac ultrasound can detect the presence of blockages in the arteries to the heart if a region of the heart is seen to have reduced pumping function during stress.

Link: http://medicine.iupui.edu/krannert/programs/echo/dobutamine/

Stress echocardiography:

Definition

Definition of stress echocardiography :

SE is an effective method for the evaluation of

myocardial ischemia, based on the detection of

“ Stress induced regional wall motion abnormality”.

About SE

Accuracy of SE in the detection of significant

coronary artery disease is 80-90%.

SE is superior to ETT and can be comparable

to nuclear stress imaging. SE is safe and economical. Mortality 1 in 1000

Pathophysiology

Pathophysiology :

Exercise and inotropic stress normally provoke a generalised increase of regional wall motion andthickening, with an increment of ejection fraction mainly caused by a reduction of systolic dimensions.

Regional systolic dysfunction is usually caused by coronary artery disease, but cardiomyopathiesmay also show regional variation in function.

Cont…

The presence of residual viable tissue is more

common in hypo kinetic than akinetic

Segments & least common in dyskinetic segments.

Ischemic cascade Myocardial ischemia due to coronary luminal obstruction

Decreased myocardial perfusion ――> [NS,PET,CPE]

Metabolic changes ――> [ PET scan]

Diastolic dysfunction ――> [Stress Echo]

Systolic dysfunction ――> [Stress Echo]

ECG change ――> [ECG]

Chest pain ――> [History]

Importance of SE:

SE can differentiate viable myocardium from

the scarred myocardium which may help

whether there will be any benefit from the

revascularization or not.

Cont…

The severity of valvular disease Hypertrophic cardiomyopathy Exercise induced pulmonary

hypertension

Contraindications to SE:

1. Unstable angina2. Severe base line hypertension3. Uncontrolled arrhythmias4. Mobile LV thrombus5. Severe Aortic stenosis6. HOCM7. Decompensated HF.

Stressors

Stressors :

Exercise Pharmacological agents Atrial pacing

TREADMILL

Methodology

Methodology :

Patient’s preparation

Equipments

Performing the test

Patient’s preparation

Patient’s preparation

Written consent from the patient.Avoid heavy meal several hours

before the test.Rate limiting drugs like beta blockers

should be stopped 3-5 half lives.Standard connections for a 12 lead

ECG.

Equipments

Equipments:

Exercise echocardiographic machine with standard hemodynamic monitoring equipment is needed.

Resuscitation equipments and defibrillator should be available for emergency crisis.

Software for the echocardiographic machine is necessary to acquire digital images and to allow side by side comparison of pre test with post peak stress images

Performing the test

Exercise stress echocardiography :

Treadmill exercise echocardiography Upright bicycle echocardiography Supine bi cycle exercise

echocardiography

Treadmill exercise echocardiography

Supine bi cycle exercise echocardiography

Exercise stress test:

Exercise stress is preferred over non exercise stress because it is more closely reproduce daily activities .

Images are to be obtained at peak exercise with bicycle ergometry while the patient continues to exercise.

Sensitivity will be reduced if the images are not taken within 90 sec after exercise.

End points for exercise SE:

Target HR (85% of APMHR)Chest pain and dyspnoeaSevere hypertension( Sys>220 mm of Hg, Dia > 110

mm of Hg)Hypotension( Sys < 90 mm of Hg or fall of

> 20 mm of Hg from the base line).Ventricular tachycardia or sustained SVTDevelopments of WMA in at least two

contiguous segments

Advantages DisadvantagesTreadmill Widely available

High workloadPost stress imagesMild ischemia may revert

Upright bicycle Imaging during exercise Technically difficult

Supine bicycle Imaging during exerciseDopplers readily available

Low workload

Dobutamine Continuous imaging Side effects

Dipyridamole Continuous imaging Side effects

Pharmacological stress echocardiography

Dobutamine stress echocardiography Dipyridamole / adenosine stress echocardiography

American society of echocardiography (ASE) In 2007, American society of echocardiography (ASE) guidelines

recommended “ Dobutamine” as the 1st line agent for pharmacologic

stress echocardiography.

Dobutamine

Sympathomimetic drugs which causes increase ionotrophic, increase chronotrophic and increase Blood pressure.

Plasma half life is 2-3 minutesLow dose dobutamine causes (+)

ionotrophic effect through cardiac α₁ and β₁ receptors

thus causing increase contractality of heart. Higher dose causing (+) chronotrophic

effects through cardiac β₂ receptors.

Dopamine vs Dobutamine

Contraindication for dobutamine :

Unstable ventricular arrhythmias

Other factors

1. Unstable angina2. Severe base line hypertension3. Uncontrolled arrhythmias4. Mobile LV thrombus5. Severe Aortic stenosis6. HOCM7. Decompensated HF.

How to start with Dobutamine

Dobutamine:

Started with 10 microgram /kg/min and then increase every 3 minutes to 20,30,40 μgm/kg/min.

If 85% of APMHR is not achieved at 40 μgm/kg/min then a 3 min 50 microgram/kg/min may be used.

If dobutamine alone is not effective then we may use Inj Atropine (.25-.50 mg) I/V every minute starting at the 40 μgm/kg/min of dobutamine.

Max 2 mg Atropine can be used.

Side effects :

Most serious- arrhythmia provocation.

Rare but serious – Cardiac arrest,

Arrhythmia, MI.

Less serious – Tremor, nervousness, marked

hypotension( due to ischemia

and dynamic outflow tract obstruction).

Combat with the side effects of Dobutamine

Emergency management for S/E :The effect of dobutamine may be

reversed if angina or other severe side effects

develops by Giving…

Inj Esmolol (0.5 to 1 mg/kg body wt)

over 1 min

or Inj Metoprolol ( 2 to 5 mg/kg body wt)

over 2-5 min

WMA grading :

Normal Hypokinetic : marked reduction in endocardial

motion and thickening . Akinetic : virtual absence of

inward motion and

thickening Dyskinetic /paradoxical wall motion

during systole.

Interpretation:

Causes of false positive and false negative stress echo:

Myocarial zone : coronary vessels

Sample pictures of DSE

Apical 4 chamber view:

Apical 2 chamber view :

Short axis view :

Parasternal long axis view :