What Does Prolonged QT on ECG mean?
Doctor can value if the QT interval happens in the right amount of time . If it takes longer than usual , it is called a prolonged QT separation . The upper demarcation line of a normal QT interval depends on factors such as age , sex , and the regularity and speed of the heart rate .
Long Q - T syndrome ( LQTS ) is one of the most common inherited syndromes related to sudden death . It has been denominate as a channelopathy or disease of ionic channel . It is known that the cardiac activeness potential exist since a sodding balance between the ionic depolarisation and repolarization currents , which are raise thanks to the correct functioning of the like ion channels . Therefore , a alteration in the genes that cipher for these line is translated into an imbalance in these stream . Normal ventricular repolarization is raise by the balance between the sodium and atomic number 20 in currents and the potassium outward currents ( K+ ) . The last unity are many but may be grouped into two , those in mission of repolarization in the initial form of the action mechanism electric potential , which is called transient outward currents and those care with the rest of the repolarization that is known as former rectifier currents . There are many mutant that may tempt negatively the ion channels . The moment of these chromosomal mutation can be classified into three radical : affection of the channel´s permeableness , a magnetic variation of the channel´s activation and dysfunction in the channel´s inactivation .
About the Q-T Interval
A normal ventricular repolarization is symbolise by the ST section and the T wave in an electrocardiogram ( ECG ) . Nevertheless , the electrocardiographic parameter with which Dr. have to valuate the continuance of repolarization is the QT interval .
It is critical to remember that the Q - T musical interval comprises not only to repolarization but also depolarization since it includes the QRS complex . This fact is essential to get the picture why it can be lengthened in the front of conductivity disorders , and not only by alterations in repolarization .
In the present suit , the electrocardiogram ( ECG ) which shows a long Q - T syndrome is characterized by an alteration in repolarization , which is abnormally long . direct the said premise of the sense of balance between inwards and outward currents , a LQTS can be bring about by alterations in the potassium ( K+ ) channels , which consistently decrease the outward current of K+ .
It can also occur if modification of sodium or calcium duct increase in an abnormal way the entrance to the cell of any of these ions . In any case , such prolonged repolarization can result broadly privilege by certain precipitating factors , in a specific eccentric of polymorphic ventricular tachycardia whose characteristic morphology reflects the torsade of the tissue .
The rough-cut denominator of sustain QT syndromes is the prolongation of this interval . However , there are certain particular feature of the ST segment and the T moving ridge that let suspecting the presence of a specific variant . The differential diagnosing of the three main variants can be made through the electrocardiogram , although their solvent are not exact since the genotype / phenotype human relationship is not exact .
Seven variants of the disease are presently experience and the therapy includes pharmacologic and non - pharmacological measures .
The syndrome can also answer to secondary causes due to the manipulation of cardiological and non - cardiological drug and this form of presentation is more frequent than that of genetic source .
The long Q - T syndrome has offered Doctor of the Church a unequalled and valuable understanding of the rudimentary mechanism of cardiac electrical natural process . New genes have been discovered and the association between the genetic defect and the clinical phenotype has provide a clearer view of the roles of ion channels in the conclusion of QT intervals and their regulation . The disease has also offer the exonerated example of the importance of obtaining inherited information about affected role because this is not only important for the medical prognosis of the disease but is currently understandably important for individualized therapy . succeeding research at the clinical and molecular point will doubtless increase the identification number of specific targets for cardiac arrhythmia control , not only in this rare disease , but in many other congenital and larn cardiac arrhythmias .
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