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STRESS TESTING: INDICATIONS - Northwestern Cardiology Fellows

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Stress Testing
Source Elstead and experience
STRESS TESTING: INDICATIONS
1. Precordial chest pain
2. Determine prognosis and severity of
disease
3. Evaluation of arrhythmia
4. Evaluation of functional capacity and
make exercise prescription.
5. Evaluate congenital heart disease i.e.
shunts right-sided pressures
STRESS TESTING:
ABSOLUTE CONTRAINDICATION
• Patient with acute MI
• Patient with acute myocarditis or
pericarditis
• Patient with unstable progressive angina
• Patient with rapid ventricular and atrial
arrhythmias
• Patient with 2nd and 3rd degree AV block
• Acutely ill patient ie with infection,
hyperthyroidism or severe anemia
STRESS TESTING:
RELATIVE CONTRAINDICATION
•
•
•
•
•
•
•
Aortic stenosis
Hi-grade LVOT
Suspected left main equivalent
Severe hypertension 240/130 (Gracin: max 180)
Severe ST depression at rest and history of angina
Congestive heart failure – rales, edema
AAA (adenosine most forgiving type of stress test)
STRESS TESTING: WHEN TO TERMINATE
THE EXERCISE TEST
* Blood pressure or heart rate drops
* Hypertension - 220 systolic or 110 diastolic especially if
headache or visual changes
* Severe ST depression i.e. 2mm in 2 contiguous lead
* Patient has reached or exceeded the predicted maximum heart
rate (need 85% nuclear 15-20 bpm over 85% for stress echo)
* VT or runs of three or more
* Atrial tachycardia, atrial fibrillation, or atrial flutter
* 2nd or 3rd degree heart block
* Angina pain
* Dyspnea, faint, fatigue
* Muscular pain of arthritis and claudication
* Patient looks vasoconstricted – pale and clammy
ST ABNORMALITIES
upsloping
2mm upsloping ST depression at .08
sec after the J point (the tail end of
QRS complex)
horizontal
1mm horizontal ST depression
downsloping
1mm downsloping ST depression
ST DEPRESSIONS
ST depression distribution does not correlate to
coronary territory at risk.
ST depressions are particularly specific on
Adenosine and dipyridamole stress but less specific
on dobutamine protocols.
ST depressions are often falsely positive for
ischemia with hypertension, digoxin, hypokalemia,
and women.
ST ELEVATIONS
ST elevations reflect transmural ischemia and are
significant in exercise, adenosine stress and DO
CORRELATE to coronary territory at risk.
The exception is Dobutamine, which often has
ischemic changes not strictly correlated to ischemia.
T-WAVE INVERSIONS
T-Wave inversions are not specific and you do
not need to wait until they return to normal
before phasing out of the study.
BRUCE PROTOCOL
Stage 1
Stage 2
Stage 3
Stage 4
Stage 5
Stage 6
Stage 7
0-3 min
3-6 min
6-9 min
9-12 min
12-15 min
15-18 min
18-21 min
1.7 mph
2.5 mph
3.4 mph
4.2 mph
5.0mph
5.5 mph
6.0 mph
10% grade
12% grade
14% grade
16% grade
18% grade
20% grade
22% grade
5.0 Mets
6.8 Mets
9.4 Mets
13.3 Mets
16.6 Mets
19.5 Mets
22.7 Mets
Mets are defined as:
Metabolic equivalents + Multiples of 02
consumption of 3.5 ml/kg/min by a person
in the sitting position. Describes functional
capacity.
Rate pressure product = Max HR x Max SBP
(25,000 is a good effort) Useful if Hr is low
and SBP is high.
Modified Bruce: 2 minute intervals ВЅ stages
Speed is constant grade increases.
Naughton Protocol: 2 minute interval at 2 mph
with grade changes 0%, 3.5%, 7%, 10.5%, 14%,
17.5%, 20%
Bicycle Protocol
Upright and Reclined
Reclined is harder physically as legs are above the heart
level. We do upright. Can watch RVSP rise with exercise.
Start at 25 watts 60 rpm increase by 25 watts
usually to 125 watts. Goal - still 85% max
HR. Use a Dobutamine format on the echo
machine.
ADENOSINE/DIPYRIDAMOLE
(PERSANTINE)
Adenosine Protocol
•140 mcg/kg/min for 6 minutes and inject MIBI at 3
minutes
•Can do 4 minute and inject MIBI at 2 minutes and
spare the patient the misery.
Adenosine and Dyperidamole - vasodilatory drugs
Normal vessels dilate while atherosclerotic vessels
do not , leading to an imbalance of blood flow
favoring the normal vessels causing a “defect” in
atherosclerotic vessels’ distribution.
ADENOSINE STRESS
•Contraindicated in bronchospasmic patients:
Most COPD are not bronchospasmic. Ask if patient was ever
intubated, prednisone dependent or nebulizer dependent.
1. Rx stop infusion
2. Rx Theophylline
•Contraindicated in high gradient AV block:
If block down Rx, stop infusion, Rx atropine.
•If patient is on Theophylline or Dyperidamole chronically, hold
drug for 24 hours.
•Caffeine extinquishes the effects of Adenosine and you do
not really have a stress test.
ADENOSINE THALLIUM IS
ESPECIALLY GOOD IN PATIENTS
1. LBBB – native or PACEMAKER induced:
Stress and Dobutamine – both from the
inability to interpret septal wall defects due
to LBBB. There is not as much variation in
motion of septum in adenosine stress.
2. Pre-op AAA
NUCLEAR IMAGING
• Thallium – Thallium
• Thallium – Sestamibi exercise
• Sestamibi – Sestamibi for very obese
patients – 2 days, more Sestamibi on stress
day
• Adenosine – walk test – save one hour of
wait time to image stress and avoid
bradycardia and symptoms
(Short)
Apex
(Vertical)
Sept
(Horizontal)
Inf
Berman, DS ; 1st Virtual Congress of Cardiology
DOBUTAMINE protocol for echo or
nuclear imaging
• Catecholamine – Increases HR and BP, but also
vasodilates so BP drop.
• Start at 5 mcg/kg/min if looking for viability but
usually 10, 20, 30, 40, 50 mcg/kg/min for 3 minutes
infusions (begin imaging at 2 minutes)
• Use Atropine in .25 mg increments – start at 30
mcg/kg/min if HR is less than 100 there.
Cautions in Dobutamine
• Caution in:
– Rapid Afib, VT – use metoprolol 5 mg IV I mg/min push
– Hypertension – dobutamine can raise or lower blood
pressure - may need to stop if you are starting out high.
Can use atropine to get to goal if note BP is going to be
limiting.
– Migrainers can get severe vasodilatory headaches
– Schizophrenic or other mentally unstable patients may
not tolerate the catecholamine effects of dobutamine –
test may need to be aborted.
DOBUTAMINE STRESS ECHO
Dobutamine stress echo is especially good for
• Asthmatics
• Obese patients – can dodge the anterior wall
attenuation artifact of nuclear imaging
16 SEGMENT MODEL
Diagram of the modified 16-segment model
with areas of coronary artery distribution
shown as areas of stippling or cross hatching.
The overlap areas are represented as a
combination of the graphics in the overlap
territory. ANT = anterior; 4C = four chamber;
INF = inferior; LAT = lateral; LAX = long axis;
POST = posterior; SAX PM = short axis at the
papillary muscle level; SEPT = septal; 2C = 2
chamber.
Segar DS et al. JACC 1992; 19:1199
WALL MOTION SCORE
Give each segment a score.
Normal – 1
Hypokinetic – 2
Akinetic – 3
Dyskinetic – 4
Aneurysmal – 5
Add up all segment scores and divide by number of
segment seen. 1 is normal.
******* WMS 2.5 or greater is a poor prognosis.
A 16-segment model can be used, without the apical cap, as described in an ASE 1989
document.
A 17-segment model, including the apical cap, has been suggested by the American
Heart Association Writing Group on Myocardial Segmentation and Registration for
Cardiac Imaging. Will be most useful if and when echo perfusion imaging is available.
Lang et al. J Am Soc Echocardiogr 2005;18:1440-1463
Typical distributions of the right coronary artery (RCA), the left anterior
descending (LAD), and the circumflex (CX) coronary arteries. The
arterial distribution varies between patients. Some segments have
variable coronary perfusion.
Lang et al. J Am Soc Echocardiogr 2005;18:1440-1463
Caveats in Stress echo
• False positives are seen in patients with
hypertensive responses to exercise
and in patients with cardiomyopathies.
The LBBB does not disqualify a patient from a
stress echo as you CAN read the anterior wall
looking for an LAD lesion. The septal and
anteroseptal walls are influenced by the LBBB
so can not be used.
Sensitivity Specificity
• ECG alone 53% vs 83%
• Spect 90% vs 80%
• Echo 85% (*80% single vx) vs 85%
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