07/26 2012
Electrocardiogram (ECG)
The most important ventricular tachycardia diagnostic method for cardiac rhythm ECG. Because there are somearrhythmias, and rarely last for different lengths of time, often not possible to diagnose one
ECG recordings. Then we utilize other methods such as. ECG recording with an electrode in
esophagus, a telephone recording ECG (telelink), exercise tests, dynamic ECG, electrophysiological
conducting an investigation of the heart and other.
Electrolytes and cardiac arrhythmias
Changes in the concentration of electrolytes may cause rhythm problems, so we must be patient withcardiac arrhythmia, alert for any associated electrolyte disturbance. Introducing drugs in a patient who has an incorrect electrolyte concentration, can trigger new, life-threatening
arrhythmias.
Potassium (K +)
Normal serum potassium is 3.8 to 5.5 milimolov per liter (mmol / l). The human body isapproximately 160 to 200 g of potassium, 98% of the cells ga, ga, only 2% is in extracellular fluids.
Lack of potassium (hypokalemia) promotes discharge of cells with hidden avtomatizmom (ectopic
cells), which can cause atrial, atrial-ventricular (Atria-ventricular, AV)
nodal and ventricular premature stimulation (extrasystole). The ECG recognize hipokalemijo in shortening
ST segment, T-wave changes and U-wave phenomenon.
The occurrence of premature beats (beats) in the absence of potassium is particularly expressed, if at the same time in the body
also a lack of calcium (hypocalcaemia). Decreased levels of potassium also slows work ritmovnika,
so that there are other discharges (ectopic) cells derived from such incentives for early
contraction of heart muscle. Lack of potassium in the works Purkinejeva conductive fibers, so that the cause,
plus a charge, thereby reducing the tension on the cell membrane.
The increase in potassium (hyperkalaemia) reduced cell membrane voltage, amplitude and speed of action
potential to prevent cell membrane permeability to sodium, which ultimately affects the poor translation
stimuli.
When hyperkalaemia are typical ECG changes:
shortened life of the ST
narrow and tall T wave,
If the serum potassium level is greater, much more pronounced changes in the R-zobcu, which is becoming
all minor and T wave merges with the wave U
the beginning of the PR interval becomes all the more so in the ECG at high concentration in serum potassium
We do not see more P-wave,
in severe hyperkalemia (approximately 10 mmol / l) changes occur in the form of the QRS complex, which becomes wider,
may occur after complete atrial-ventricular (AV) block, and then cardiac arrest (asystole).
If the concentration of potassium in the blood (serum) strongly increased (about 7.5 to 8, 0 mmol / l) due to sinusoidal
bradycardia, a slow heart work, then develops between the block and atrial ritmovnikom (son-atrial block)
occurs while accelerating the operation of AV node or Purkinejevih fibers, which can take control stimuli
the cardiac conduction system (heart rhythm disturbances occur).
Sodium (Na +)
Sodium affects the deviation from center line (amplitude), velocity, and the overall action potential duration. Inhuman body is about 60 g of sodium and 50% in extracellular fluids. Physiological limit of sodium
between 138 and 146 mmol / l. Sodium is very important to maintain cell membrane potential.
It is necessary for normal functioning of nerve and muscle cells. Its effect on blood pressure is still not
completely understood. Most probably it is more important than his own soda proportion of potassium.
About hipoosmolalnosti (hyponatraemia) occur when the sodium level falls below 135 mmol / l. Reduction
extracellular sodium (hyponatremia) skrajšanaja lead to action potential duration. More than 20%
reducing levels of sodium (severe shortage) reduced the amplitude of action potential so that they do not
longer able to transmit signals to neighboring cells and lead to interruption of impulses in the heart.
Calcium (Ca ++)
It is normal plasma calcium from 2.2 to 2.6 mmol / L. Changes in serum calcium levels mainly in the ECGchange the Q-T interval. In the absence of calcium (hypocalcaemia), this interval is prolonged, the
hypercalcemia is reduced. Hypocalcaemia in the T-wave usually positive, but rounded in hypokalaemia.
Lack of calcium resulting from parathyroid gland disease, Rickets, poor absorption of food poisoning in
Vitamin D and other rare diseases.
Magnesium (Mg ++)
Magnesium behaves like potassium. In cells ga is about six times less than potassium. The nervous system workssimilar to calcium. Magnesium is needed as a catalyst for many cellular enzymatic reactions, especially those who
they are bound by the digestion of carbohydrates (sugars) and the transfer of phosphorus. A low concentration
magnesium causes increased irritability, nervous system, blood vessel dilatation in the periphery, disruption of
orientation, jerky muscle spasms (seizures) and cardiac arrhythmias. Often the reasons for the drop
magnesium in the body is incorrect, one-sided diet, often taking laxatives on water and excessive drinking
alcoholic beverages. We find low levels of magnesium in patients with angina pectoris, cardiac
rhythm, and digestive problems and in older people. The value of magnesium is lower in patients
fresh suffering a heart attack. The daily requirement of magnesium is around 0.9 grams.
Phosphorus (P)
Phosphorus is the functional unit of phospholipids, carbohydrate, and high energy nukleoproteidovnucleotides. Its main role is fitting into the structure of bones and teeth. It is also important for
proper functioning of the heart and kidneys and the transmission of nerve impulses.
Carotid sinus massage
Left and right common vein neck (common carotid arteria) passing the trachea obliquely upwardsand the triangle (trigonum caroticum) of the fourth cervical vertebra share in foreign
(Arteria carotid externa) and internal arteria (internal carotid arteria). At the inner arteria has been expanded and this place called the carotid sinus (sinus caroticus). In this cavity are receptors, which are sensitive to changes in blood pressure. Receptors leads inlet (and outlet) nerve fibers that connect brain ninth nerve (nervus glossopharyngeus).
Carotid sinus massage leads to incentives baroreceptorjev and through reflex arc activation
vagrant tenth cranial nerve (nervus vagus), which slows the heart. Massage of the carotid
sinus can lead to a reduction in pressure and a significant decrease in the heart rate, so we
perform massage gently and be prepared for emergency assistance.
Before carrying out the massage we need to listen to the cervical area arteria. arteria diseases (noise above
vein) does not perform carotid massage. The patient lies with his head pushed back and the side opposite the whirlpool
city. Duty to monitor pulse and heart rhythm, it is best that the patient is connected to a monitor or ECG.
Massaged by gently pressing on the door arteriao, if not success, massaged more, usually 5 seconds or
Massage it on the other side. Never massage both sides at the same time!
The massage slow sinus tachycardia, interrupted ventricular tachycardia (PSVT), slow
ventricular rate in atrial movement. If the patient does not respond to massage, this is not
exclude the diagnosis. In ventricular paroxysmal tachycardia usually massage does not work.
Thyroid hormones may affect the heart rhythm
Changes in the ECG is also influenced by excessive and insufficient secretion of thyroid hormone (hyperthyroidism and
hypothyroidism).
In diseases due to excessive secretion of thyroid hormone, hyperthyroidism, are the most common changes
sinus tachycardia and heart muscle disorder discharge chambers (repolarisation). Changes occur
due to increased sympathetic nervous tension; in older people often occurs atrial depolarisation
(Atrial fibrillation), younger and prolonged PQ interval, can also experience a higher R teeth as an indicator
damage to the heart muscle.
In diseases due to lack of secretion of thyroid hormones, hypothyroidism, are more significant changes in
ECG. In particular, we find sinus bradycardia with mikrovoltažo and matched or even negative T-tines.
Changes resulting from damage to the heart muscle (myocardium miksedematozne change) and the pericardium
(Effusion).