Supraventricular tachycardia (SVT)

We had a lesson about ICU nursing and care for critically ill patient about two weeks ago. We got an assignment related to that lesson. We were supposed to to choose one type of heart arrhythmia and write about here in the blog. I chose supraventricular tachycardia (SVT). I didn't have any special reason why I chose SVT.
The Evidence-Based Medicine Guidelines (EBMG) define SVT:  "it is typically a narrow-complex regular arrhythmia with an abrupt onset and termination". SVT starts rapidly and lasts usually from minutes to hours. Structure which causes the arrhythmia is located in the atrium or somewhere between the atrium and ventricular of the heart. SVT causes pulsating feeling in the chest and low blood pressure because the minute volume of the heart decreases 40% from the normal during arrhythmia. Usually the drop in blood pressure is improved quickly back to normal because of the compensatory mechanisms used by the cardiovascular system. The drop in blood pressure causes symptoms like dizziness, nausea, vapour, blurring of the vision, decreased level of consciousness, pain or feeling of constriction in the chest. Need to urinate more often than usually can be linked into the attack also the person might be tired after the attack. Even though these attacks are mainly harmless minor of these attacks might be dangerous if they are prolonged.
The attack may occur when there is a combined effect of a trigger, right kind of circumstances, and a structure in the heart which causes arrhythmia. Extrasystoles are the most common triggers of tachycardia also moves (e.g. bending over, yawning, coughing,  be frightened, or after hard physical or mental stress)  which causes abrupt vagal nerve stimulation. The right kind of circumstances for the tachycardia may occur if the person is tired, stressed, has used great amounts of substances, has infectious disease etc. If the conduction pathway are unusual or the heart tissue has changed because of a disease the structure of the heart is more likely to cause arrhythmia.
Usually SVT stops by itself and they occur seldom. If SVTs starts to occur more often and the symptoms become more severe curative treatment (catheter ablation) and prophylactic treatment (drug therapy) should be considered. If the diagnosis has been made and the person tolerates the arrhythmia quite well the agal stimulation is the first-line treatment for a acute episode of SVT. If the vagal stimulation is ineffective the person should be given adenosine i.v.. If the tachycardia is very fast or the person doesn't tolerate the arrhythmia cardioversion might be needed.

I have used Terveysportti as a reference in this report.
http://www.terveysportti.fi.ezproxy.jamk.fi:2048/ebmg/ltk.koti
http://www.terveysportti.fi.ezproxy.jamk.fi:2048/dtk/oppi/koti?p_artikkeli=kar00059&p_haku=supraventricular%20tachycardia