Pre-hospital Emergency Treatment for Narrow Complex Tachycardia - Essay Example

Pre-Hospital Emergency Treatment Narrow Complex Tachycardia Pre-Hospital Emergency Treatment Narrow Complex Tachycardia Narrow complex tachycardia ora tachycardia with a QRS complex less than 120 msec, reflects a rapid activation of the ventricles by way of the normal His-Purkinje system, which means that the tachycardia originated either within or above the AV node. That could be the sinus node, the atria, the atrioventricular node the His bundle, or some combination of these sites. This indicates that a narrow complex tachycardia may be one of many tachycardias (Podrid, 2008). This paper will discuss how that diagnosis is made pre- hospital, as well as the epidemiology, pathophysiology, and pharmacology of those arrhythmias. There will be a general overview of the arrhythmias followed by more specific with treatment guidelines. Supporting research will be investigated in an effort to determine credible practice guidelines. The narrow complex tachycardias include sinus tachycardia (ST), atrioventricular nodal reentrant tachycardia (AVNRT), atrioventricular reentrant tachycardia (AVRT), atrial tachycardia (AT), inappropriate sinus tachycardia (IST), sinoatrial nodal reentrant tachycardia (SNRT), junctional ectopic tachycardia (JET), nonparoxysmal junctional tachycardia (NPJT), atrial fibrillation (AF), atrial flutter (AFI), and multifocal atrial tachycardia (MAT). Symptomology that may occur with these tachyarrhythmia’s are hypotension, heart failure, or pulmonary congestion, shortness of breath, renal failure, shock, decreased consciousness, angina or acute MI (Podrid, 2008). If these symptoms are occurring cardioversion is recommended. The state of stability of the patient who is pre-hospital is of course the focus of care. Determining the nature of narrow QRS tachyarrhythmia is necessary and an EKG is of great importance at this point. When we consider pathogenesis, reentry is the most common cause of QRS complex tachycardia. The mechanism of reentry requires two distinct pathways or tissues in the heart that have different electrophysiological properties that are linked proximally and distally, forming a circuit that is anatomic or functional (Ansdorf & Ganz, 2009). You will note the following diagrams. Figure 2: Atrioventr... Figure 3: Atrial tac... Figure 5: Multifocal... Figure 6: Atrial flu... Figure 8: Atrial fib... Figure 9: Atrial fib... Figure 11: Atriovent... Figure 12: (A) Atrio... AVNRT as shown above is characterized by two pathways within the AV node. AVRT also shown above is characterized by an extranodal accessory pathway connecting the atrium and ventricle. Wolf-Parkinson White syndrome would fall into this category. SNRT and reentrant tachycardia do not involve the AV node (Arnsdorf, 2009). There are also other mechanisms that lead to narrow QRS complex tachycardia. Those include automaticity (sinus tachycardia), abnormal automaticity (ectopic atrial or junctional tachycardia) and triggered activity (Arnsdorf, 2009). Evaluating in all of these cases whether a patient is hemodynamically stable as well as the regularity of his rhythm is important. Most of these are associated with a regular rhythm, with the exception of atrial fibrillation. Atrial fibrillation may be noted to have an irregular atrial rate of 350 to 600 with a ventricular rate of 90-170. P waves may not be identifiable at all. If the P waves are not identifiable a differential diagnosis may be made by using the valsalva maneuver or carotid massage. The Valsalva maneuver temporary slows the SA nod and AV node conduction. Patients are ask to bear down hard with a closed glottis. Patients must be continuously monitored while doing this. This may sometimes be used on a patient while preparing to use an adenosine challenge. Carotid massage temporarily slows the SA node and AV node conduction. External pressure is placed on the carotid bulb which stimulates the baroreceptors in the carotid sinus.(Arnsdorf, 2009). This to can be used temporarily while preparing for adenosine and needs to be monitored. There are contraindications to the use of Carotid massage. Those include previous stroke, a carotid bruit, and MI, or ventricular tachycardia. Pre-hospital pharmacologic treatment includes several acceptable medications. The research shows that what drug is used may depend on what part of the country is studied. There are, however, a few drugs that are well accepted by the majority of studies. This review will include adenosine, verapamil, and diltiazem (Lim & Anantharaman, 2002). EMT’s across the country have become well trained in the ordered use of these drugs. Lim, Anantharaman, and Teo (2002) studied the effects of verapamil and diltiazem as slow infusions used pre-hospital to cause a spontaneous termination of SVT. The study included patients that showed SVT on EKG and had not had carotid massage or vagal manoeuvre. Anyone who was hemodynamically unstable was excluded from the study. The study ended with a result of no difference between the use of verapamil and the use of diltiazem. It proved that calcium channel blockers were safe and efficient in terminating SVT, when used by well trained staff (Lim et. al., 2002). Both verapamil and diltiazin are calcium channel blockers. They inhibit the calcium ion from crossing the cell membrane during cardiac depolarization, producing relaxation of the coronary vascular smooth muscle, dilating arteries, and slowing SA and AV conduction times. There are quite a few side effects including the chance of cardiac arrest. However, most often there is edema, CHF, bradycardia and nausea. Headaches, drowsiness and dizziness are also common. Furlong, Gerhardt, & Farber et al (2005). Studied the use of adenosine as the first line prehospital drug to be given by EMS personnel. The reason for the study was to determine the safety and efficacy of IV adenosine given for narrow complex tachycardia. This study included only those patients that had PSVT by EKG at 160 beats per minute or greater. The interpretation was performed solely by paramedics and EKG transfer was not available. Only hemodynamically stable patients were included. Of those patients that were converted by the use of adenosine, 16 required only one dose, nine required two doses and three required two additional doses. There were no poor outcomes by arrival at hospital and all of the patients had converted. Adensine slows conduction through the AV node and can interrupt the pathways that cause the rapid heart rate. It may abruptly interfere with reentry or circus rhythms. This is the reason it is such a good field drug as it is able to act promptly with few doses and convert rhythm quickly, preventing further compromise of the patient. This was followed by a study done Turley & Murray (2008). The results were essentially the same. Adenosine was a safe drug to be used first line by paramedics in ambulance transfer to hospital, to stabilize rhythm. The only clear recommendation was that is never being given without properly functioning equipment and EKG. This is the drug of choice to be given by paramedics in many places for treatment of PSVT. If the arrhythmia is atrial fibrillation, however, these is evidence to say that IV diltazem may be the first line drug of choice and studies show that it is safely administered by EMS under the same circumstances. In conclusion, narrow complex tachycardia may be extremely compromising to a patient. There are many types of narrow complex tachycardia and they may be caused from various reasons. This paper has reviewed a few of the most often seen rhythms as well as the medications most often seen given prehospital by EMT’s. This is an emergency situation as it compromises all of the organs including the brain from poor cardiac output related to rhythm and rate. Verapamil and diltazem have in the past been quite popular but adenosine has become the easiest to use with the least complications. There are many studies on adenosine and its effects and this paper has reviewed only a few of those. Bibliography Abarbanell, NR, Marcotte MA, Schaible BA, & Aldinger GE. (2001). Prehospital Management of rapid atrial fibrillation: recommendations for treatment Protocols. Amercan Journal of Emergency Medicine. 19(1). Pgs 6-9. Retrieved on Jan. 4, 2010 from http://www.ncbi.nlm.nih.gov/pubmed/11146008?ordinalpos Anantharaman, L. (2002). Slow infusion of calcium channel blockers in the emergency management of supraventricular tachycardia. Resuscitation. 52(2) pgs 167-74. 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