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Recurrent intraoperative silent ST depression
responding to phenylephrine
-Rajkumar S Guide: Dr. Indira mam
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An unusual case of recurrent, symptomless
inferior wall ischemia in an apparentlyhealthy male with no history of coronary
artery disease after a spinal block and its
successful management
Case Report
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A 46-year-old, 72 kg, man was scheduled for elective
right knee replacement for post traumatic osteoarthritis.
No other significant present history
Past history Known hypertensive, well controlled on oral
amlodipine 5 mg OD.
Exercise tolerance mildly restricted since last 2
years due to pain associated with osteo arthritis, taking
occaional NSAIDS. No H/O angina, palpitaion, diaphoresis.
History
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Hemoglobin was 12.3 mg%
Biochemical profile / lipid profile were normal
CXR / ECG showed no abnormality
Intermediate risk was explained to the patient and a
written informed consent was taken.
Advised to remain NPO from midnight and 2 units ofpacked cells were arranged.
Pre OP
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Standard monitoring was
connected which showed ECGwith normal sinus rhythm with
HR 74/ min, BP was 116/ 70
mm/Hg
Saturation was 100% on room
airA 16 G IV line was secured
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CSE block was given in right
lateral position with 12.5 mg of 0.5
% hyperbaric bupivacaine alongwith 25 mcg fentanyl was given
intrathecally through L3- L4
interspace
18G catheter was threaded into
the space and fixed to skinPatient was turned to supine
position and sensory level of block
was found to have reached around
T5 after 10 min.
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Progressed to 3.4 mm in the next 5 minutes in the lead II alone.
Later it showed a value of +0.2 and +1.2 in lead V5 and aVL
respectively.
After 15 min, the ecg started to show down sloping ST depression
In the diagnostic mode monitor recognized the a ST depression of 2 mm
Patient was asked for any chest pain or heaviness which the patient
denied.
Intra op events
1
2
3
4
5
6
BP was 106/62 with HR 117 / min
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Since ECG pattern indicative of inferior wall ischemia
and there was increasing tachycardia, besides
augumenting fluids vasopressor was decided to use.
Phenyl ephrine 75 mcg bolus was given IV.
Pattern changed to normal, HR dropped to 100 / min and
BP picked up to 127/ 74 in next 5 minutes.
Diagnosis of ischemia remained uncertain as the lowest
BP was 106/ 62 mm / Hg.
? Ischemia
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Image just after 1stdose of phenylephrine
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After 10 minutes ST depression of 3.2 mm in
lead II with reciprocal ST elevation in aVL of
+1.1 mm was seen.
BP dropped to 101/ 59 mm / Hg with HR 110 /
min
Another phenyl ephrine bolus of 75 mcg wasgiven IV rhythm returned to normal in 5 minutes.
Till now patient received 1 litre of crystalloid and
500 ml of colloid.
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Image after normalization of ST segment
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A similar episode reoccurred over next 20
minutes and a phenylephrine infusion wasstarted @ 50 mcg/min
ST segment values became normal
HR became 84 / min
Surgeon was asked to withhold surgery after 2nd
episode as blood loss could precipitate MI
Surgery was deferred
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Renormalization after phenylephrine
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Quantitative assay of troponins were sent
immediately, A qualitative troponin after 4 hours
Both of which turned out to be negative for MI.
Cardiology evaluation later revealed a 70 %
occlusion of RCA.
An elective coronary stenting was done
subsequently.
Post op
PCI
Angiography
Troponins
Negative
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Coronary perfusion
pressure =
aortic diastolic pressure
left ventricular end
diastolic pressure
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Administering nitrates in this case may have aggravated
the tachycardia and increased myocardial workload.
Short acting beta-blockers are recommended to control
this tachycardia but they did not administer it as the bloodpressure was falling.
Pathophysiology of intraoperative MI is different than commonly seen ST
depression MI where plaque instability is the cause of ischemia.
Intraoperative MI is more of a demand-supply failure and hence the
treatment lines are different as well
Why Phenyl ephrine?
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Phenylephrine preferentially acts on arterial alpha-receptors as
compared to venous. This is a potential disadvantage for a diseased
heart as it would increase afterload and increase cardiac oxygen
demand.
- Phenylephrine is a directly acting pure alpha 1
agonist which not only increases the blood
pressure but also lowers the heart rate and thus
was the drug of our choice in the given situation.- Ischemia is often associated with hypotension
that lowers cardiac perfusion pressure for a
normal heart.
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- A prolonged ST depression of >20-30 min or a
cumulative duration 1-2 h can lead to MI.
- Our patient showed three episodes ofsignificant ST depression but the duration of each
was limited to less than 10 minutes and hence did
not lead to a MI.
Why it didnt progress to infarction
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Patient felt no chest pain or heaviness..
The spinal block given to the patient may beresponsible for obscuring the manifestations of
ischemic pain.
The highest sensory block noted was up to T5;
the autonomic block may have been higher dueto differential blockade and involving the
cardiac sympathetic plexus T1-T4.
Absence of symptoms..
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When demand exceeds
supply
Inadequete myocardial oxygenation
leading to accumulation of anaerobic
metabolites
Myocardial infarction is defined as the death of
myocardial myocytes due to prolonged ischemia
Ischemia Discussion..
Death of
Myocytes
Toxic
metabolites
Ischemia
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In patients without previous history of coronary artery
disease (CAD), the incidence of perioperative myocardial
infarction (PMI) amounts to 0.6%
Most often the intraoperative cardiac ischemia involves
the left coronary artery and presents as ST segment
depression in the left sided leads
Ischemia Discussion..
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?
1) Down sloping ST
segmentdepression
2) More than 1.5 mm
3) Reciprocal lead
involvement
4) Associated withsymptoms / signs
Specific ST segment elevationNon specific ST elevation
1) Up sloping ST segment
depression
2) lower than 1.5 mm
3) No reciprocal lead
involvement
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Long-term mortality is higher
Frequently Non-Q wave
50% SILENT! Perioperative ischemia (esp prolonged) is
associated with adverse cardiac events.
Real-time detection may allow therapeutic
intervention.
Ischemia duration strongly associated with
peak cTn-I level (concept of troponin leak)
Ischemia preceded in all cases by heart rate
increase
Are perimyocardial ischemia different?
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Clinical predictors
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History angina, recent or past MI, HF, symptomatic arrhythmias,presence of pacemaker or ICD
Physical Examination general appearance, rales, elevated JVP,carotid and other arterial pulses, S3 gallop, murmurs
Comorbid Diseases
Pulmonary
Diabetes Mellitus
Renal Impairment
Hematologic Disorders
Ancillary Studies - ECG almost always indicated, blood chemistriesand chest X-ray based on history and physical findings
General Approach to the Patient
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Remote MI ( >1
month)
Stable angina
Compensated
CHF
Creatinine 2.0
Diabetes
IntermediateMajor Low
-Acute or recent
MI (< one month)
-Unstable orsevere angina
-Large ischemic
burden (stress
testing)-Decompensated
CHF
-Significant
arrhythmias
Clinical Predictors of Increased cardiac morbidity in
perioperative period
-Advanced Age.
-Abnormal ECG.
Rhythm other
than sinus.
-Low functional
capacity.
-History of
stroke.
-Uncontrolledsystemic
hypertension
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Intraperitoneal, Intrathoracic, Suprainguinal vascular procedures
0 predictors = 0.4%, 1 predictor = 1%, 2 predictors = 2.4%, 3
predictors = 5.4%
Hx of heart failure
DM requiring insulin
H of ischemic heart disease
Hx of cerebrovascular disease
Preoperative serum creatinine > 2.0 mg/dL
Independent predictors of major Perioperative cardiac
complications:
Revised Goldman Cardiac Risk Index
1
2
3
4
5
6
7
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-Intraperitoneal
/intrathoracic
-Orthopedic
-Head & neck
-Carotid
endarterectomy
-Prostrate surgery
Intermediate (1-5%)High risk ( > 5% )
-Endoscopic
-Breast
-Skin
-Cataracts
-Superficialprocedures
Low risk (
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Supplemental
Preoperative Evaluation
Noninvasive testing in preoperative patients indicated if 2 or more of
following present:
Intermediate clinical predictors (Canadian Class I or II angina, prior
MI based on history or pathological Q waves, compensated or prior
HF, or diabetes)
Poor functional capacity (
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Importance of exercise tolerance
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Pathophysiology ofperioperative Cardiac
Ischemia
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Unstable plaque / CAD
LVH
Hypercoagulable state and thrombosis
Catecholamines Pain / stimulus
anemia
Depth of anesthesia
BP swings pain
anemia/HYPOVOLEMIA ( neuraxial block, blood loss, venous return
compression, release of tourniquet )
Intraop factors
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Symptoms: usually none Pain, shortness of breath, sweating, nausea and
vomiting, altered mentation Clinical signs: usually none
Sweating, CHF, HR changes, arrhythmias,hypotension
ECG: key perioperative monitor
Pulmonary artery catheter Increased PCWP, new V waves on PCWP tracing
TEE SWMA, change in mitral regurgitation, diastolic
dysfunction, decrease in global contractility
How to Monitor for Ischemia
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Lead selection II and V4 or V5
ST SEGMENT CHANGES (most specific)
T wave changes
esp inversion in high risk groups
Arrhythmias
New conduction abnormalities
New atrioventricular block
Heart rate changes
ECG Monitoring for Ischemia
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ECG
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ECG
Depression: subendocardial ischemia,
poor localization Horizontal / downsloping depression >
0.1 mV (1 mm) at 60-80 msec after Jpoint
Upsloping depression > 0.15 mV at 80
msec after J point
Elevation: transmural ischemia, good
localization> 0.1 mV
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Conduction disturbances
R wave amplitude changes
Hyperventilation Electrolyte changes, hypoglycemia
Hypothermia (< 30)
Body position changes / retractors
Autonomic NS changes e.g. spinal Myocardial infarction or contusion
Neurological changes (trauma, SAH)
Acute pericarditis
ECG monitoring for Ischemia
Other Causes of Acute ST Segment Changes
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TEE is a highly sensitive for monitoring ischemia
In the event of ischemia there is development of new
regional wall motion abnormalities decreased systolic wall thickening
ventricular dilation
It can detect ischemia much earlier than ecg.
Limitations
Pre-intubation events are missed
Image plane may miss events in other areas of the
myocardium
TEE
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Myocardial ischemia reduces left ventricular compliance
that results in increased pulmonary artery occlusion
pressure and presence of V waves. impaired systolic function can lead to decreased cardiac
output which can be detected.
PCWP > 18-20 mm Hg
Limitations:
It is not sensitive for myocardial ischemia
Pulmonary artery cathetrisation may lead to increased
morbidity
Pulmonary artery catheter
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Hypotension along with decreasing
cardiac output can result from either1) hypovolemia
2) ventricular dysfunction
Measurement of stroke volume variationcan rule out hypovolemia
Arterial pressure waveform
analysis
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Arterial wave form
Hypotension along with
decreasing cardiac output
can result from either1) hypovolemia
2) ventricular dysfunction
Measurement of stroke
volume variation can rule out
hypovolemia
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Systolic pressure variation (SPV)
particularly increased D down, indicates
hypovolemia.
The greatest clinical use of systolic
pressure variation has been in the early
diagnosis of hypovolemia.
If we can rule out hypovolemia, systolic dysfunctioncan be diagnosed
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MI may be best detected with cardiac Troponin T
concentrations.
TnT and TnI levels may rise more than 20 times
above the reference range within 3 hrs after onset of
chest pain and may persist for up to 10-14 days
CPK-MB is not useful intraoperatively because the
leakage of these enzymes into the circulation canoccur 8-24 hours after an MI.
CD40 ligand - marker for platelet-monocyte
aggregation as thrombus is being formed
Markers
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Monitoring for ischemia
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Pre op procedures
PCI
CABG B blockers
Alpha-2 Agonist (Mivazerol, Dexmedetomidine,
Clonidine)
Statins Control BP
Antiplatelets and anti coagulants (if indicated)
Prophylactic placement of intra-aortic balloon
counterpulsation device
Management (prevention)
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Reduced
Hemodynamic
Stress
??? Platelet
Action
??? Metabolic
Increased
Diastole
Improved myocardial blood flow
Decreased
Ventricular
Arrhythmias
Reduced VF threshold
Spectrum of
potential
benefits of
beta-blockade
Spectrum of
potential
benefits of
beta-blockade
Plaque
stabilization
Antiarrhythmic
action
Improved oxygen
supply/demand
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Management of Suspected Intraoperative
Ischemia
FIRSTLY Secure system ensure adequate oxygenation, BP, volume, Hb
SECONDLY Optimize hemodynamics - especially tachycardia and blood
pressure
THIRDLY, consider Increase FiO2
NTG
Increased monitoring CVP, PCWP, TEE
Inform surgeon, alter surgical plan
Postoperative management
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Management of Suspected Intraoperative
Ischemia
Check ECG (calibration, mode, previous ECGprintouts)
Verify automatic ST segment analyses Look for associated features
Arrhythmias, hypotension
Increased filling pressures or new V waves
TEE changes (check all LV segments) Consider
Other causes of ECG change
Patients risk of CAD
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Deepen anesthesia
IV -blockadeEsmolol, 20100 mg, 50200 g/kg/min
Metoprolol, 0.52.5 mg
Labetalol, 2.510 mg IV nitroglycerin Nitroglycerin,
33330 g/min
Hypertension, tacycardia
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Ensure adequate anesthesia
Change anesthetic regimen
IV -blockade
Normotension tachycardia
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Deepen anesthesia
IV nitroglycerin or
Nicardipine, 15 mg, 110 g/kg/min
Hypertension, normal heart rate
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IV -agonist Phenylephrine, 25100 g
Norepinephrine, 24 g
Alter anesthetic regimen (e.g., lighten)
IV nitroglycerin when normotensive
Hypotension, tachycardia
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Lighten anesthesia
IV ephedrine Ephedrine, 510 mg
IV epinephrine Epinephrine, 48 g
IV atropine Atropine, 0.30.6 mg
IV nitroglycerin when normotensive
Hypotension, bradycardia
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IV Nitroglycerin
IV Nicardipine,
No hemodynamic abnormalites
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The Buffington ratio is a useful index. It
stipulates that patients suffering fromcoronary stenosis are at particular risk of
myocardial ischemia when their mean
arterial pressure is less than the heart rate(MAP/heart rate
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g
Ischemia Persists with Optimal
Hemodynamic
Keep increasing NTG (may combine with vasopressor ifhypotension)
May increase monitoring CVP, PCWP, TEE
CONSIDER Acute Coronary Syndrome (unstable angina,infarct) Aspirin or ketorolac
Heparin (5000 U bolus, then 1000 U/hr) if surgery permits
beta-blockade (aspirin & beta-blockade reduce risk of infarct andmortality)
Observe for complications- arrhythmias, CHF, infarct
Cardiology consult - urgent reperfusion - within 12-24 hours(especially if persistent ST segment elevation)
PTCA most practical (thrombolysis CI after surgery)
? IABP
P t ti M t f P i ti
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Postoperative Management of Perioperative
Ischemia
CONSIDER
ICU or CCU postop and/or cardiology referral
Surveillance for periop MI ECG immediately postop and on day 1 and 2
Cardiac troponin at 24 hrs and day 4 (or hosp
discharge) (CK-MB of limited use)
LONG TERM cardiologist
Risk factor management
Aspirin, statins, beta-blockade, ACE inhibitors
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In Greek mythology, the night has twin sons, Thanatos (death)
and Hypnos (sleep), who carry flaming torches pointing toward
the floor, to light a path through the dark
Juan Marin placed a small light between Thanatos and Hypnos
indicating the flame of life the anesthesiologist must guard.
The upper half of the emblem shows the rising or setting sun of
consciousness.