Additional methods of examination

Clinical blood analysis - leukocytosis with mild nuclear shift to the left occurs in a few hours after onset of chest pain, reached the peak at 2-4 days and normalized in a week. The degree of leukocytosis depends on amount of damaged myocardial tissue. Accelerated ESR is observed at 2-3 days from onset of chest pain, reached maximal level till 2 week and normalized at 3-4 weeks.

Markers of myocardial infarction are plasma enzymes, which are normally concentrated within cardiac cells. During the necrosis of cardiomyocytes their membranes destroyed and the enzymes released at first at microcirculation and later at systemic circulation. Thus myocardial infarction causes a detectable rise in the plasma enzymes which serve as laboratory markers of necrosis: creatine kinase, lactate dehydrogenase, aspartate aminotransferase, troponin T and I, myoglobin. Optimal time for estimation of myocardial markers of necrosis depicted at table.

Optimal time for estimation of myocardial markers of necrosis

Markers	Optimal time for estimation of myocardial markers of necrosis
Myoglobin	In 1-2 hours after chest pain
Creatine kinase	Every 12 hours 3 time
Creatine kinase MB	In 60-90 minutes after chest pain, every 12 hours 3 time
Lactate dehydrogenase	In 24 hours after chest pain, one time
Troponin T	In 12 hours after chest pain, one time
Troponin I	In 12 hours after chest pain, one time

Baseline and peak elevation of markers of myocardial damage is different. Dynamic of laboratory markers of myocardial infarction is depicted at table

Dynamic of laboratory markers of myocardial infarction

Markers	Norma	Time from onset of myocardial infarction
		Baseline elevation hours	Peak elevation hours	Normalization days
Creatine kinase MB	0-4 ME/L	3-6	12-24	1,5-3
Lactate dehydrogenase	15-30%	12-24	24-72	7-14
Aspartate aminotransferase	28-125 mmol/l	8-12	24-48	3-5
Troponin T, I	Less 0,1 mkg/1	3-12	12-48	3-16
Myoglobin	20-66 mkg/1	1-4	6-7	1

ECG: one of the most significant uses of a 12 lead ECG is to aid in determining whether a myocardial infarction has occurred.

The usual first finding in an infarction is elevation of the ST-segment, which occurs some hours after infarction. Hours to days later the T-wave inverts, diminution of the size of the R-wave and the Q-wave becomes deep and wide. The height of the R-wave is directly proportional to the amount of living tissue that escapes death. In case of full thickness myocardial infarction the R-wave is disappeared. Days to weeks later the ST-segment returns to near normal isoilectric line position. Weeks to moths later the T-wave becomes upright again, but Q-wave may remain abnormal. As the infarction heals the Q-wave may remain as the only sign of an old coronary occlusion. Since a deep and wide Q-wave is often indicate of an old infarction. The Q-wave may considered abnormal if it is over 0,03 second wide and if it is greater in depth than one fourth the height of the R-wave.

Echo-CG: two-dimensional echocardiography may assess the cardiac structures, pericardium and ascending aorta, allows identification of regional wall motion abnormalities, valvular abnormalities, global left and right ventricular function and detecting important complications such as cardiac rupture, ventricular septal defect, mitral regurgitation and pericardial effusion.

Radioisotope scintigraphy by technetium-99m-pyrophosphate. Scintigraphy is generally used for the diagnosis of myocardial infarction in patients hospitalized late after the onset of symptoms in which cardiac enzymes are no longer elevated or are unreliable. Imaging is optimal 2-7 days after myocardial infarction. Focal increases in technetium pyrophosphate uptake are generally diagnostic of infarction. This technique is highly sensitive (>90 %) in detecting large transmural infarctien but is less reliable in the detection of small non-Q-wave myocardial infarction.

Radionuclide ventriculography allows to reveal right and left ventricular ejection fraction and assessment of regional wall motion abnormalities. Because radionuclide ventriculography provides less information regarding the cardiac structures, echocardiography is generally preferred in the initial evaluation of patients with myocardial infarction