) may be due to rhythm abnormalities that can occur during the peri-arrest period. The tachycardia algorithm has been designed to enable the non-specialist ALS provider to treat a patient effectively and safely in an emergency.
The first step in assessing and treating all deteriorating or critically ill patients is to use the ABCDE approach (Airway, Breathing, Circulation, Disability, Exposure).
If the patient does have adverse features this implies that the patient’s condition is unstable and they are at risk of deterioration. So the next course of action is synchronised cardioversion.
Supraventricular And Ventricular Arrhythmias: Medical Management
If cardioversion fails to terminate the arrhythmia and adverse features persist, administer 300 mg amiodarone IV over 10-20 min and perform a repeat synchronised cardioversion. The loading dose of amiodarone can be followed by an infusion of 900mg over 24 h.
The next stage in the algorithm (for both broad and narrow QRS) will ask you to determine if the patient’s rhythm is regular or irregular.
A regular broad complex tachycardia may be ventricular tachycardia (VT) or a supraventricular rhythm with bundle branch block. In a stable patient, if there is uncertainty about the origin of the arrhythmia, intravenous adenosine during a multi-lead ECG recording may clarify the nature of the rhythm. This should be done under expert supervision.
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Otherwise, treat with amiodarone 300 mg IV, administered over 20 - 60 minutes, followed by a further 900 mg over 24 h.
If the same rhythm in this patient has previously been confirmed to be supraventricular tachycardia (SVT) with bundle branch block, give adenosine IV as first-line treatment, as described for treatment of a regular narrow complex tachycardia.
If the QRS is narrow and the rhythm is regular, in the absence of adverse symptoms you should start with vagal manoeuvres, recording a multi-lead ECG during performance of these.
Management Of Inappropriate Sinus Tachycardia
If the arrhythmia persists and is not atrial flutter, give adenosine 6 mg as a very rapid intravenous bolus, recording a multi-lead ECG during the injection. If there is no response give a 12 mg bolus. If necessary give a further 12 mg dose if there is no response.
If either vagal manoeuvres or adenosine restores sinus rhythm, the rhythm was probably re-entry paroxysmal SVT. You should record a 12-lead ECG in sinus rhythm and can give further adenosine if the arrhythmia recurs. Consider carefully whether or not anti-arrhythmic prophylaxis will be of benefit in the setting of the individual patient. If uncertain, seek expert help.Tachyarrhythmias are abnormal heart rhythms with a pulse rate of >100 beats per minute (bpm). This can be due to a variety of causes, including physiological and pathological, and is a commonly encountered issue whilst on the wards – a patient’s heart rate contributes to their NEWS score (National Early Warning Score) and thus may be a reason (alongside other observations) as to why you’re asked to see a patient.
It is useful to remind ourselves of the physiology of the heart at this point, and appreciate the relevance of a raised heart rate (HR). Remember, the mean arterial blood pressure (MAP) is very important when considering organ perfusion. The MAP is a function of the cardiac output (CO) and the systemic vascular resistance (SVR), where the CO is determined by the stroke volume (SV) multiplied by the heart rate.
Supra Ventricular Tachycardia Rythms
As such, if there is a change in one of these parameters (SVR, SV, or HR), then we can expect any of the other values to compensate to maintain an appropriate blood pressure. The
Example is during sepsis, where infection causes vasodilation and a fall in the SVR, thereby causing a rise in the HR to prevent haemodynamic collapse. Therefore, if a patient has a raised HR, always consider why this may be occurring from a haemodynamic perspective.
In the normal heart, the heart rate (HR) is determined by the sinoatrial node (SAN), and the interaction between the sympathetic and parasympathetic nervous systems. At rest, the parasympathetic nervous system predominates, and the resting HR is set between 60-100 bpm. Where there is an increase in the sympathetic outflow, therefore, or a reduction in parasympathetic stimulation to the heart, there will be an increase in the HR to cause sinus tachycardia (a HR >100 bpm where the pacemaker impulse originates from the SAN).
Acute Therapy Of Narrow Qrs Tachycardia In The Absence Of An...
• Post cardiac transplant – absence of vagal stimulation, owing to nerve severance, leads to a HR set by the ‘natural’ internal pacemaker of the transplanted heart’s sinoatrial node (SAN) at 100-110 bpm
There are various pathological causes of tachycardia, and these can be thought of as intrinsic (cardiac) causes, and extrinsic (non-cardiac) causes. Moreover, it is helpful to subclassify cardiac causes into regular-and-irregular, and narrow-and-broad complex tachycardias. The latter is further classified into monomorphic and polymorphic tachycardias (see the flow chart, and table, below).
Intrinsic causes of tachyarrhythmias are usually due to an abnormal electrical focus (located in the atria, conducting system, or the ventricles) that overrides the rate set by the SAN, or due to a reentry circuit within the heart – remember, the HR will be determined by any pacemaker / electrical focus that is depolarising at the fastest rate.
Sinus Tachycardia Diagram
Risk factors associated for developing a tachyarrhythmia include: cardiac ischaemia (i.e., previous MI, ischaemic heart disease), presence of an accessory pathway, age, smoking, alcohol, left ventricular systolic dysfunction (LVSD) and recreational drug use (sympathomimetics, i.e., cocaine)
The flow chart below shows the potential causes of tachycardia. Sinus tachycardia is not included in this flow chart, but would otherwise cause a narrow complex, regular tachycardia in the absence of any conduction abnormalities.
For those who prefer tables, below is another way to think about the cardiac causes of tachycardia. Similarly, sinus tachycardia is not included in this table.
Pregnancy Related Inappropriate Sinus Tachycardia: A Cohort Analysis Of Maternal And Fetal Outcomes
*A supraventricular tachycardia (in this context) is used to describe any regular, abnormal tachycardia that originates from above the ventricles (i.e., atrial tachycardia, AVRT, AVNRT)
**The term aberrancy (or aberrant conduction) describes an abnormality of conduction through the ventricles that cause a widened QRS complex (broad complex).
Remembering back to fundamental physiology, we can derive multiple reasons as to what would cause a non-cardiac origin of the tachycardia. However, further causes can be seen below and, although not comprehensive, the mnemonic: ABCDEFG HIT can be a helpful memory aid.
Atrial Tachycardia: Practice Essentials, Background, Anatomy
In the below, we have included congestive cardiac failure (CCF) in the mnemonic, as acute decompensation of CCF can often be caused by non-cardiac issues (i.e., infection). It also helps with the mnemonic. However, it is worth remembering that having severe LVSD (left ventricular systolic dysfunction) in itself is a very arrhythmogenic state, even when not decompensated (whether from LV dilatation or scar tissue from previous infarcts, etc)- this is why implantable cardioverter defibrillators (ICDs) are implanted into these types of patients. Severe LVSD tends to cause a lot of ventricular arrhythmias, and it can be an arrhythmia that causes decompensation in the first place. This is why LVSD is also included in the cardiac causes above.
*Here we refer to congestive cardiac failure (CCF) as a ‘non-cardiac’ cause, as acute decompensation of CCF is often triggered by an underlying non-cardiac issue, and cardiac causes (in this instance) is referring to problems of arrthythmogenesis. It also helps with the acronym.
When taking a history, it is important to be comprehensive and to proceed in a structured manner, asking first with the presenting complaint. Then proceed through the history up to, and including, the system’s review.
Paroxysmal Supraventricular Tachycardia: Background, Etiology, Epidemiology
Tachycardia does not always cause symptoms alone, and it may manifest via another underlying issue (i.e., left leg cellulitis causing leg pain). However, particularly in instances of a cardiac cause, common and important features you should always enquire about include:
Other features to consider include other causes of tachycardia, as outlined earlier, and these should be included in the general history taking. For example, when exploring the patient’s social history, you can enquire about the acute use of alcohol and sympathomimetics / illicit drug use, or if the patient complains of a productive cough, this would raise concerns for an underlying chest infection.
All patients presenting with an elevated HR should be approached using an A-E examination. The standard examination is not always informative, but certain features in the examination may be indicative of particular diagnoses / causes / precipitating factors. Cardiac-specific signs include
Supraventricular Tachycardia: An Overview Of Diagnosis And Management
The main diagnostic investigation that all patients should have is a 12-lead ECG. The ECG can offer a huge plethora of information and is vital in helping determine underlying causes.
*In this context, a full blood screen would include an FBC, U+E, CRP, Bone profile, TFT, troponin, magnesium, glucose, toxicology screen (i.e., TCAs, cocaine)
The management of tachycardia should first be determined by the clinical status of the patient using an A-E approach. In any patient with haemodynamic instability and / or ‘life-threatening features’ (shock, syncope, myocardial ischemia, or heart failure), they should be managed as part of the Resuscitation Council UK’s guidelines
Inappropriate Sinus Tachycardia Causes And Treatment
It should be remembered that most tachycardias are a symptom of an underlying condition i.e., sepsis. If the patient is haemodynamically stable, then waiting for the treatment of the trigger to work i.e., antibiotics is usually the best approach. This is not to say, however, that all tachycardias are due to an underlying, non-cardiac condition (as we
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