Cardiovascular diseases(CVD) are the main cause of mortality in most
countries, a range of diseases related to the circulation, like ischemic heart disease (heart attack) and cerebro-vascular disease (stroke).
Ischemic heart disease
Ischemic heart disease is caused by accumulation of fatty deposits lining in the internal wall of the coronary artery and so restricting blood flow to the heart muscle. Early recognition of heart disease could save thousands of lives each year.
When looking at heart diseases, seven classic symptoms can be recognized:
- Dyspnea: is a medical term for shortness of breath. The abrupt onset of dyspnea is often due to heart failure, whereas chronic shortness of breath is more likely to be a symptom of coronary artery disease or valvular heart disease.
- Palpitations: The heart of an average person beats about 500.000 times per week and ordinarily people are unaware of their heartbeat. Palpitation is the awareness of one’s heartbeat and is often quite disturbing when it appears. Palpitations occur as irregular or very rapid heartbeats, known as arrhythmias.
- Syncope: is simply a loss of consciousness. The most common cardiac cause of syncope is an irregular heartbeat or arrhythmia.
- Oedema: is a swelling or puffiness of tissue. The swelling is due to retention of water or lymph fluid in the cells of the tissue. It is a common sign of heart disease, indicating a diminishing of pumping of the right side of the heart.
- Cyanosis: is the bluish discoloration of the skin and mucous membranes. It is caused by too little oxygenated blood flow through surface tissues.
- Fatigue: Persons suffering from fatigue will start the day with a relatively normal energy level, then become increasingly tired through the day to the point of exhaustion. This is because of the heart muscle has become weakened and lost its ability to pump enough blood and oxygen for the body to function normally.
- Angina: is the primary symptom of coronary artery disease. It consists of chest pain caused by myocardial ischemia, a condition in which the amount of oxygen the heart muscle requires exceeds the amount it receives. One can differentiate between stable and unstable angina.
- Stable angina: the appearance of the chest pain after physical effort or stress.
- Unstable angina: the frequency and severity of chest pain increases, and attacks may occur during rest or may be provoked by less effort than usual.
The underlying cause of a decreasing the supply of oxygenated blood is a progressive narrowing of the open channels (the interior lumens) of the coronary arteries, due to arterioscleroses. Atherosclerosis is a condition in which scattered lesions, plaques or atheromas, appear on the inner wall of the coronary artery.
An acute Myocardial infarction (AMI) occurs in the myocardium when there is a marked decrease in the oxygen supply to an area of the muscle causing a zone of dead or dying tissue
Sudden death results from the sudden, abrupt loss of heart function.
Diagnosis
An important diagnostic tool is the determination of the serum cardiac markers.
Cardiac Markers
Three serum markers for the detection of heart damage are playing an important role in the routine diagnosis of AMI. Creatinkinase (CK), Myoglobin and Troponin. These three intracellular proteins are released whenever damage occurs to the myocard (surgery, ischemia)
Brain natriuretic peptide (BNP)
Brain natriuretic peptide (BNP) levels are simple and objective measures of cardiac function. These measurements can be used to diagnose heart failure, including diastolic dysfunction.
In contrast to atrial natriuretic peptides (ANP/NT-proANP), which originate mainly from atrial tissue, BNP related peptides are produced mainly from ventricular myocytes.
BNP is produced and secreted in response to excessive stretching of cardiomyocytes (heart muscle cells) This can be because the heart muscle does not contract or relax effectively or both and so reducing the performance of the heart as a pump.
BNP like other cardiac natriuretic peptides have potent diuretic, natriuretic, and vascular smooth muscle–relaxing effects and the effect of reducing the blood volume and pressure BNP provides an accurate test for the diagnosis and prognosis of congestive heart failure (CHF) and for cardiovascular damage follow up. CHF is a complex of signs and symptoms resulting from inadequate cardiac pump function.
The main symptoms of CHF are fatigue, shortness of breath and fluid retention, especially in the legs and lungs. It has been shown that BNP is a better diagnostic parameter than the measurement of the left ventricular ejection fraction, which used to be the reference standard for the diagnosis of heart failure. The clinical outcome of BNP or NT-pro BNP is the same. During stretching of the cardiomyocytes, pro-BNP, BNP and NT-pro BNP are present in the blood and cross-react due to the presence of the same epitopes.
Troponin (Cardiac Troponin I (cTnl))
Troponin I (TnI) has three isoforms: cardiac, fast skeletal and slow skeletal and out of them cardiac troponin I (cTnI) is highly specific to the myocardium. When the myocardium is damaged, cTnI is released into the blood. The level of cTnI becomes abnormally high 3-4 hours after the onset of acute myocardial infarction and reaches the peak 10-16 hours after the onset. The level of cTnI remains abnormally high for 5-8 days after the onset. When compared to Myoglobin or Creatine Kinase-MB (CK-MB), the degree of its change in relation to the cut-off value is much greater for cTnI (undetectable in healthy individuals) and as a result, it is possible to detect minute myocardial lesions. In addition, increased cTnI levels in heart failure patients indicates latent cardiomyopathy.
CK-MB (Creatine Kinase-MB)
CK-MB, one of the isoenzyme of Creatinine Kinase is one of the most important myocardial markers with a well-established role in confirming acute myocardial infarction (AMI). In AMI, plasma CK-MB typically rises some 3 to 8 hours after the onset of chest pain, peaks within 9 to 30 hours and returns to baseline within 48 to 72 hours. CK-MB measurements are also useful in monitoring reperfusion during thrombolytic therapy following AMI.
Myoglobin
Myoglobin is one of the most important myocardial markers used in ruling out acute myocardial infarction (AMI) within 2 hours of admission because of chest pains. AMI disrupts cardiac cell membranes, releasing intracellular cardiac proteins into the vascular system. Myoglobin, being the smallest of these markers, diffuses rapidly throughout the vascular system and provides the earliest indication of AMI. Myoglobin levels rise between 0.5 – 2.0 hours after the onset of chest pain and peak within 5-12 hours. The kidneys rapidly eliminate myoglobin from the system, restoring normal circulating concentrations within 16-36 hours. Since the protein rapidly clears from the system, myoglobin concentrations can reliably indicate reinfarction.
D-Dimer
D-Dimer is a by-product of the breakdown of fibrin (fibrous protein making up blood clots, composed of 2 ‘D’ and 1 ‘E’ domains). The D-Dimer concentration is an indicator for the fibrinolytic activity of the plasmin-enzyme in the vascular system.
- Help rule out the presence of a thrombus, especially in case of:
Deep vein thrombosis (DVT)
Pulmonary embolism (PE)
Strokes
- Determine if further testing is necessary to help diagnose diseases and conditions that cause hypercoagulability, a tendency to clot inappropriately.
- Help diagnose Disseminated Intravascular Coagulation (DIC) and to monitor the effectiveness of its treatment.