Cardiac Profile Tests(Biochemical )DR ROHINI C SANE

Cardiac Profile TestsIHD –ISCHAEMIC HEART DISEASE: CORONARY BLOOD SUPPLY TO THE

MYOCARDIUM IS INADEQUATE AS COMPARED TO ITS DEMAND

1. THE MOST COMMON CAUSE is ATHEROSCLEROSIS

2. CONGENITAL ANAMOLIES OF THE CORONARY ARTERIES

3. CORONARY EMBOLI OF VARIOUS NATURE FROM DIFFIRENT SOURCES

(A ) Vegetation of bacterial endocarditis

(B ) Atheromatous plague from major coronary artery

(C) Diminished blood supply due paroxysmal tachycardia

(D) Severe anemia ,CO2 poisoning ,decrease oxygen supply to myocardium

IHD –ISCHAEMIC HEART DISEASE

Clinical manifestation

I .Arrhythmias /autonomous disturbance

II. Angina pectoris

a. Clinical syndrome

b. Sudden attacks of chest pain of short duration

Precipitation factors

1.Physical exertion

2. Stress

3. Trachycardia

4. Heavy meals

5. Exposure to cold

6. Administration of insulin/T3,T4

Coronary atheroma

Coronary atheroma :lipid deposit within intimal coat of coronary arteries

↓

Narrowing of lumen

↓

Diminished blood supply to myocardium

↓

Formation of thrombus in coronary arteries

↓

Complete occlusion

↓

Infarction /necrosis

ATHEROSCLEROSIS

The modifiable risk factors of Cardiac diseases

1. Hyper lipidemia

2. Diabetes Mellitus

3. Smoking

4. Hypertension

5. Stress

6. Obesity

7. Heavy Physical activity

8. Diet high content of saturated fat & cholesterol

The non-modifiable risk factors of cardiac diseases1. Heredity: individuals more susceptible to premature atherosclerosis

2. Age : after middle age increase incidence of atherosclerosis

3. Sex : male > women risk of atherosclerosis

CLASSIFICATION OF CARDIAC PROFILE TESTS

GROUP I : DIABETIS MELLITUS - DISTRUBED CARBOHYDRATE METABOLISM ATHEROGENIC RISK FACTORS PRE RENAL CONDITIONS

GROUP II : CARDIAC RISK EVALUTION TESTS

GROUP III: CARDIAC INJURY PANEL TESTS

CLASSIFICATION OF CARDIAC PROFILE TESTS

• GROUP I :

1. Blood Glucose

2. Blood Urea Nitrogen ( BUN )

3. Serum creatinine

4. Serum Electrolytes

CLASSIFICATION OF CARDIAC PROFILE TESTS

GROUP II :CARDIAC RISK EVALUTION TESTS

1. Serum Total Cholesterol

2. Serum HDL cholesterol

3. Serum TOTAL/HDL cholesterol

4. Serum VLDL /LDL cholesterol

5. Serum Triglyceride

CLASSIFICATION OF CARDIAC PROFILE TESTS

GROUP III: CARDIAC INJURY PANEL TESTS

1. Serum Creatine Phospho Kinase ( CPK )

2. Serum Glutamate Oxaloacetate Transferase ( SGPT )

3. Serum Lactate Dehydrogenase ( LDH )

4. Serum Hydro Butyrate Dehydrogenase ( SHBD )

GROUP III: CARDIAC INJURY PANEL TESTS

1. To assess severity of heart disease

2. To follow trend of the disease

3. To determine post operative disease

4. ECG do not permit clear diagnosis

↓

20% infarct are silent are silent

( elderly Diabetes Mellitus /Hypertension patients )

5. CPK, LDH ,SGOT, SHBD levels in serum for diagnosis & prognosis

6.Concentration of CPK,LDH ,SGOT ,SHBD α size of infarct

SERUM LACTATE DEHYDROGENASE (LDH )

• Principle of estimation : Decrease in UV Absorbance at 340 nm as LDH catalyzed reaction progresses

• LACTATE + NAD + PYRUVATE + NADH + H +

• NORMAL SERUM LEVELS OF LDH = 125- 290 U/ L

• OCCURRENCE : HEART ,LIVER ,SKELETAL MUSCLES ,ERYTHROCYTES IDH ,AMI LDH1 > LDH2 ( FLIPPED PATTERN )

• PHYSIOLOGICAL CONDITION : LDH1 < LDH2

ISOENZYME NORMAL RANGE ( % ) UNITS /L (SERUM )

LDH 1 20 – 30 100

LDH 2 32 – 40 115

LDH 3 17 – 23 65

LDH 4 03 - 13 40

LDH 5 04- 12 35

Cardiac biomarker :Iso-enzymes of Lactate dehydrogenase (LDH )

ENZYME HALF LIFE

LDH 1 8 DAYS

LDH 6. 8 DAYS

CPK -MB 2 DAYS

SGOT 4 DAYS

AREA UNDER CURVE ,SLOPE OF INITIAL RISE α INFARCT

Iso enzymes of Lactate dehydrogenase

Iso enzymes of Lactate dehydrogenase

LDH1 LDH5

Optimum condition

AEROBIC ANAEROBIC

Km high low

Affinity for pyruvate

low high

Synthesis of lactate

Not favored Favored

SERUM APARTATE AMINO TRANSFERASE (AST )

SERUM GLUTAMATE OXALO ACETATE (SGOT )

1. NORMAL RANGE : 6 – 25 IU/L

2. STARTS INCREASING WITHIN 6 -12 HRS AFTER CHEST PAIN

3. PEAK HRS 24- 48 HRS

4. Less specific indication of myocardial infarction as it occurrence liver, muscle ,hemolytic diseases

5. Prolonged Myocardial Ischemic ,Congestive Heart Failure increase in SGOT ( AST )

6. Increase in SGOT ( AST ) < Increase in CPK (TOTAL )

7. HALF LIFE is of small duration & returns to normal within 4-6 days

Serum Creatinine phosphor kinase (CPK )

1. Normal ( CPK- MB ) is 6% OF Total CPK activity

2. CPK /GOT ratio < 10 myocardial infarction

3. CPK /GOT ratio > 10 muscular damage

4. Silent myocardial infarction

5. Pain free infarcts Diabetes Mellitus ,Hypertension ,impaired peripheral arterial blood flow

6. ECG /Other findings

III ANGINA PECTORIS

a) Increase in CPK activity

b) Increase in arrhythmias

c) Congestive cardiac failure

Iso enzymes of Creatinine phosphokinase (CPK)

Creatinine phosphokinase (CPK)-cardiac marker

Serum Creatine phosphor kinase (CPK )

CPK MM / CPK TOTAL increased observed in

1. myocardial infarction

2. muscular dystrophy

3. Polymyositis

4. Motor neuron disorders

5. acute cerebrovascular accidents

Normal range CPK Total

Men : 20-50 IU

Women : 10-37 IU

PRINCIPLE OF ESTIMATION OF CPK (COLORIMETRIC ):

CREATINE –P + ADP+ CPK CREATINE + ATP

CREATINE + DI ACETYL + α NAPTHOL - alkaline pHcolor complex

( absorbance at 520 nm , green filter )

Serum Creatine Phospho kinase (CPK )

Precautions for estimation of CPK

(1)Patients undergone strenuous exercise before blood collection –erroneous high levels of CPK

(2)Minor tissue trauma- erroneous high levels of CPK

(3)Sample should be kept in refrigerator until test carried out

(4) Cardiac markers (follow time course after onset of AMI )

MYOGLOBIN (MB )MYOGLOBIN (MB )

1. oxygen binding protein in skeletal muscle & cardiac muscles

2. Low molecular weight : cytosolic location

3. Appearance in circulation after muscle injury

4. Myoglobin –monoclonal antibody for estimation by RIA / ELIZA/chemiluminescence

5. Temporal pattern of serum myoglobin & Creatine kinase -2 patients with myocardial infarction

MYOGLOBIN (MB )as a cardiac marker CLINICAL INTERPRETATION of Serum Myoglobin

1. Increase in serum levels after myocardial infarction as early as 1 hr(necrosis )

2. Peak values 4-12hrs

3. Myoglobin remain high 0-4hrs

4. Time period :in which CPK -2 & CARDIAC TROPONIN IS VERY SHORT .

Disadvantages of Myoglobin as cardiac marker :

1. non specific eg myoglobin increases in any form of muscle damage

2. Methods not tissue specific ( muscle /cardiac )

3. Muscle injury increase in myoglobinmisdiagnosis of AMI

CARDIAC TROPONINSI. Troponin : “contractile ”proteins of myofibrils regulatory proteins

a) Troponin C ( the calcium binding component )

b) Troponin I ( the inhibitory component )

c) Troponin T (Tropomyosin binding component )

II. Component of cardiac muscles

III. Longer Half Time –Insoluble Troponin released from infarcted heart muscle therefore circulatory levels remain high .

IV .Rise in serum Troponin continues for longer than enzymes

Comparison between cardiac Troponin I & Troponin T

Human cardiac Troponin I Human cardiac Troponin T

30 AMINO ACIDS 11 AMINO ACIDS

CARDIAC MARKERS ---SPECIFIC &SENSITIVE MUSCLUAR DYSTROPHYCHRONIC RENAL FAILURE POLYMYOSITIS

2 ISOFORMS—GENETIC ORIGIN

INCREASE OBSERVED AFTER AMI—CPK –MB& CPK -TOTAL

TROPONINS ( MARKER OF MYOCARDIAL INFARCTION )TROPONINS TYPE PROPERTY

TROPONINS C CALCIUM BINDING

TROPONINS I ACTINO MYCIN INHIBITORY ATPase

TROPONINS T TROPOMYOSIN BINDING ELEMENT

Cardiac Troponin I &TClinical interpretation :cardiac troponin ( C Tn I & C Tn T )

1. Longer half life insoluble troponin released from infarcted heart muscles within 4 to 8 hrs after onset of symptoms

2. Troponin I &C increase significantly after AMI

3. Increase in serum levels of Troponin I &C synchronizes CPK –MB & CPK –TOTAL

4. circulatory levels are maintained for 4-5 days

5. Half life of C Tn I & C Tn T is 5- 10days

6. peak values of C Tn T observed at 72 -100 hrs.

7. peak values of C Tn I observed at 24 -48 hrs.

8. low levels & undetectable serum levels are observed in individuals without cardiac disease( no false + ve or –ve values for C Tn I )

Comparison of cardiac markers

1. Increase in CPK -2 in conditions individuals without cardiac disease Therefore better risk assessment than CPK –MM .

2. CPK -2 (CPK –MB ) increase in muscle injury

3. ( C Tn I & C Tn T ) don't increase in muscle injury

4. C Tn T excellent marker for AMI VERSES muscle injury when concomitant.

5. C Tn T increases in sepsis, drug induced toxicities ,chronic diseases ,malignancies ,hematological disorder ,non cardiac surgery

6. C Tn I sensitive & specific for AMI

Biochemical Cardiac MarkersCARDIAC MARKER

ABNORMAL ACTIVITY DETECTABLE IN( hrs )

PEAK VALUE OF ABNORMALITY (hrs)

DURATION OF ABNORMALITY ( DAYS )

1 CPK ( TOTAL) 3-8 HRS 10-24 3-4

2 CPK -MB 3-8 HRS 10-24 2-3

3 LDH ( TOTAL ) 8-12HRS 72-144 8-14

4 SGOT ( AST ) 6TO 12HRS ( 24-48 4-6

5 MYOGLOBIN 1TO 3HRS 6-9 1

6 TROPONIN I ( C –T n I )

3-8 HRS 24-48 3-5

7 TROPONIN T( C –Tn T )

3-8 HRS 72-100 5-10

Homocystein as a cardiac marker

Homocystein is formed during biosynthetic pathway of cysteine from Methionine.

Cardiac profile tests –Homocysteine

Normal range : < 15 micro –moles /l (serum )

Inborn error in metabolism of Homocystein: increase serum Homocystein ( paediatric ) > 100 micro –moles /l

Free Homocysteine S S Free Homocysteine

PROTEINS ← Disulphide bridge ( )

Dimer formation decrease metabolism ( therefore increase in serum Homocystein increase risk of atherosclerosis

Molecular basis CHD :damage to lining of blood vessels ( vascular endothelium )

Increase serum Homocystein in growth of vascular muscles

Causes of Homocysteinuria

Genetic causes

• Genetic mutation within a gene coding cystathione beta synthetase

• Homocystein + Cystathione beta synthase Cystathione

Non genetic causes

Deficiency of

pyridoxal phosphate ( vitamin B6 )

Folic acid (tetra hydro folate )

Vitamin B12 ( CYANOCOBALAMINE )

HOMOCYSTEIN + (VITAMINES B6, B12 ,FA )METHIONINE

Treatment –Dietary supplementation of (VITAMINES B6, B12 ,FA ) till Serum Homocysteine decreases

Cardiac profile tests –Homocysteine• INCREASE IN SERUM HOMOCYSTEIN Homocysteinemia -coronary arterial disease

Molecular basis of coronary arterial disease (CAD )respect to Homocysteinemia

1.damage cell lining of blood vessels

2. increase growth of smooth muscles

3. Homocystein alters anti coagulant properties of endothelial cells to pro coagulant

4. dysfunction of vascular endothelium

5. damaged vascular endothelium Atherosclerosis & CAD

Methods of estimation of Homocysteine Gas chromatography, HPLC , immune assays ,Chemiluminescence

Cardiac profile tests --C reactive protein ( CRP )

1. ACUTE PHASE PROTEIN (APP ) –MOST SENSITIVE APPS

Significant increase observed in

a) Inflammatory diseases

b) After injury

c) inflammation

d) Myocardial infarctions

e) Tumors

2.NORMAL RANGE : 0.05 TO 0.20mg /L (SERUM )

Increase in Serum CRP indicates high risk of cardio vascular events

20 times increase in CRP ( > 10 mg ) suggestive of AMI

Cardiac Profile Tests- Serum Hydroxyl Butyrate Dehydogenase(SHBD )Principle of estimation of SHBD :

Alpha oxo butyrate + NADH2 +SHBD ( p H 7.4 ,phosphate buffer ) alpha hydroxyl butyrate + NAD +

SOLUTION 1 : PHOSPHATE BUFFER PREPARATION : (STABLE AT 2-8 ◦ C )

13. 97 gm K2 HPO4

2.69 gm KH2PO4

SOLUTION 2 : (0.0045 mmols/ i e 0.017 gm/dl in 2.5 ml of distilled water )

• Wave length for measurement : 340 nm ,cuvette 1 cm

Procedure : 3 ml 0f solution 1 + 0.1 ml of solution2 + sample 0.1 ml mix well ,note extinction at 340nm at 1,2,3 minutes intervals

• Determine mean absorbance & change of absorbance (∆ A / minutes )

Calculation :

• Concentration of Alpha SHBD ( IU ) = 5079 X ∆ A / minutes

• If ∆ A > 0.1 dilute sample 1: 10 with phosphate buffer

Cardiac profile tests- Serum Hydroxyl Butyrate Dehydogenase

Serum SHBD increases significantly in Acute myocardial infarction (AMI)

NORMAL RANGE OF SERUM SHBD:

• at 25◦ C 55 -140 IU

• at 30 ◦ C 65 -165 IU

• at 37 ◦ C 72 -182 IU

Cardiac profile tests- Apo proteins (Apo lipoproteins )Functions of Apo proteins (Apo lipoproteins )

1. Structural components of lipoproteins

2. Recognize the membrane surface receptors

3. Activate enzymes involved in lipoprotein metabolism

APOPROTEINS SUBGROUPS

APO A A-I, AII , AIII

APO B B100 ,B 48

APO C C I, CII,CIII

APO D

APO E

Cardiac profile tests- Apoproteins (Apolipoproteins )CLINCAL SIGNIFICANCE OF APOLIPROTEINS :

1. To assess hyper lipedemias with /without increase in LDL CHOLESTROL

2. APO PROTEIN B100 –To assess prognostic value after lipid lowering drug therapy

3. Management of AMI patients decrease risk of re infarction

APOPROTEIN TYPE NORMAL RANGE ( PLASMA) Comments

Apoprotein A 100-120 mg/dl

Apoprotein A1 < 120mg /dl increase risk of CAD > 160mg /dl Protective

Apoprotein B 100-120 mg/dl

Apoprotein B100 100-120 mg/dl >120 mg /dl HIGH RISK CAD >100 mg /dl moderate RISK CADIncrease in Apoprotein B100 ,decrease Apoprotein B100 suggestive high risk of CAD

HDL cholestrol 130-160mg/dl

LDL cholesterol 130-160mg/dl

Cardiac profile tests- Apoproteins (Apolipoproteins )APOPROTEIN TYPE MOLECULAR WEIGHT COMPONENT OF FUNCTIONS

1. APOPROTEIN A1 28016 HDL & CHYLOMICRONS

LECITHIN CHOESTEROL ACYL TANSFERASE (LCAT) ACTIVATOR

2. APOPROTEIN AII 17414 HDL & CHYLOMICRONS

SECOND MOST COMMON APOPROTEIN OF HDL

3. APOPROTEIN AIII 46465 HDL & CHYLOMICRONS

TRANSFER OF APOPROTEIN BETWEEN HDL & CHYLOMICRONS

4. APOPROTEIN B48 264000 CHYLOMICRONS NECESSARY FOR ASSESSBLY & SECRETION OF CHYLOMICRONS FROM SMALL INTESTINE

5. APOPROTEIN B100 512000 VLDL,IDL,LDL NECESSARY FOR ASSESSBLY & SECRETION OF VLDL FROM LIVER

6. APOPROTEIN CI 7600 VLDL, HDL POSSIBLE LECITHIN CHOESTEROL ACYL TANSFERASE (LCAT) ACTIVATOR

7. APOPROTEIN CII 8900 ALL MAJOR LIPOPROTEINS

LECITHIN CHOESTEROL ACYL TANSFERASE (LCAT) ACTIVATOR

8. APOPROTEIN CIII 8800 ALL MAJOR LIPOPROTEINS

ACTIVATOR OF LIPOOPROTEIN LIPASE

Cardiac profile tests- Apoproteins (Apolipoproteins )

APOPROTEIN TYPE MOLECULAR WEIGHT COMPONENT OF FUNCTIONS

9. APOPROTEIN D 22000 MAINLY HDL INVOLVED IN REVERSED CHOLESTEROL TRANSPORT OR ESTERIFIED CHOLESTEROL TO VLDL

10. APOPROTEIN E 34145 ALL MAJOR LIPOPROTEINS

LIGAND FOR BINDING OF SEVERAL LIPOPROTEINS TO LDL RECEPTORS

Cardiac profile tests-ABNORMAL FORM OF LIPOPROTEIN A ( LP a )

1. Variant of LDL

2. Synthesized in liver

3. LDL –S-S – APO B 100 ( with disulphide bridge )

4. Interfere with action of plasminogen ( clot resolution ---fibri lysis )

5. Normal concentration in plasma = < 0.30 gm /l ( <30mg/dl)*

6. High levels of LPa increases in coronary heart disease therefore forms cardio vascular risk factor

7. *Normal range racial specific, vary with ethnic group

8. Lipoprotein levels of African Americans > Caucasians ( more risk for CAD )

Cardiac profile tests-LIPOPROTEINS /ABNORMAL FORM OF LIPOPROTEIN A ( LP a )

Methods of estimation of LIPOPROTEIN A ( LP a ) :

a) Immuno Turbidometric

b) Immuno Nephalometric

c) Radiometric

d) Elisa

e) RIA