Treatment for PSVT

Welcome to Heart to Heart Nurses, brought to you by the Preventive Cardiovascular Nurses Association. PCNA’s mission is to promote nurses as leaders in cardiovascular disease prevention and management.  

Geralyn Warfield (host): Welcome to the third of a three-episode mini-series focused on paroxysmal supraventricular tachycardia, also known as PSVT. 

In our first episode, we discussed episodic rapid heart rate conditions. And in our previous, second, episode, we talked about the patient experience and the importance of patient-centered care.  

Today, we’re actually going to be focused on treatments. And my guest today is Janette Sendin. Janette, could you please introduce yourself to our audience? 

Janette Sendin (guest): Yes. Hi, everyone. My name is Janette Sendin. I am an Advanced Practice Nurse in a Clinical Nurse Specialist role in cardiology, where I have worked with [00:01:00] many patients with SVTs and for the past, like maybe, about 20 plus years.  

Geralyn Warfield (host): Well, we really appreciate you being with us today. And in some of our previous episodes we’ve discussed that each patient may experience different symptoms of PSVT. 

Could you please share with our audience some of the traditional treatments that they might be experiencing?  

Janette Sendin (guest): Sure. To begin with, let me just give a recap of SVT, or supraventricular tachycardia, which is a general term. describing a group of arrhythmias whose mechanism involves, or is above, the atrial ventricular node, or what we call the AV node. 

Immediate treatment can usually be tailored to the characteristics of the ventricular rate. By focusing on the ventricular rate, one can assign the seven clinically-relevant SVT to diagnostic and therapeutic groups based on the [00:02:00] rapidity of onset (which is sudden or gradual), the heart rate, and the regularity of the tachycardia. 

Geralyn Warfield (host): I understand that traditional treatment methods for PSVT can include both pharmacologic and non-pharmacologic treatments. I’m hoping, Janette, that you could first describe for us the non-pharmacologic options.  

Janette Sendin (guest): Yes, Geralyn. To begin with, I just wanted to emphasize that the initial assessment should distinguish between a narrow and wide complex tachycardia, determine whether the rhythm is regular or regular, and consider the rapidity of onset. 

Now let’s talk about narrow complex tachycardia, and what are the methods of treatments for this.   Both the traditional non-pharmacological, and pharmacological methods.  

So, for the narrow complex tachycardias, vagal maneuver, including a Valsalva maneuver, [00:03:00] carotid sinus massage, bearing down and immersion of the face in ice water, are carried out to break or stop the SVT by increasing vagal tone and blocking conduction through the atrioventricular node. 

Vagal maneuvers can be used to terminate an episode of narrow QRS SVT. The effectiveness of conventional vagal maneuvers in terminating SVT when correctly performed has been reported as between 19 and 54%. And this is obtained from the 2019 ESC Guidelines for the Management of Patients with SVT. 

Vagal maneuvers include different techniques used to stimulate the receptors in the internal carotid arteries. This stimulation causes a reflex stimulation of the vagus nerve which results in the release of acetylcholine—which [00:04:00] may, in turn, slow the electrical impulse through the AV node and hence, slow the heart rate. 

Many of these maneuvers can be performed with minimal risk at the bedside, or in an office setting, or at home, and can be both diagnostic and therapeutic. The Valsalva maneuver is a safe and internationally recommended first line emergency treatment for SVT, although a recent Cochrane review found insufficient evidence to support or refute its utility.  

The Valsalva maneuver has shown to be the most effective, to be most effective in adults and in atrioventricular reciprocating tachycardia or AVRT rather than atrioventricular nodal reentrant tachycardia, or AVNRT.  

A modified approach to the Valsalva [00:05:00] maneuver provides a considerable enhancement of conversion success rates, which is 43 versus 17% conversion rate. This enhanced method requires the Valsalva to be completed semi-recumbent with supine repositioning and passive leg raise after the Valsalva strain. Blowing into a 10 mL syringe with sufficient force to move the plunger may standardize the approach. 

Carotid sinus massage, on the other hand, is performed with the patient’s neck in an extended position, with the head turned away from the side to which pressure is applied. It should always be unilateral as there is a potential risk with bilateral pressure, and it should be limited to five seconds. The patient should be [00:06:00] monitored. This technique should be avoided in patients with previous transient ischemic attack or stroke, and in patients with carotid bruit.  

Other maneuvers such as facial immersion in cold water or forceful coughing are rarely used now.  

Geralyn Warfield (host): So, could you tell us a little bit more about the pharmacological treatments that are available? 

Janette Sendin (guest): Sure. Slowing the heart rate often confirms the diagnosis of sinus tachycardia, atrial fibrillation or atrial flutter and can frequently terminate AVNRT and AVRT.  

Adenosine, a very short-acting endogenous nucleoside that blocks AV nodal conduction, terminates nearly all AVNRT and AVRT, as well up to 80% of atrial tachycardias. 

Adenosine should be administered quickly at a dose of [00:07:00] 6 mg, followed by a bolus of 20 mL of fluid. Since this drug may also excite atrial and ventricular tissue—causing atrial fibrillation in up to 12% of patients and non-sustained ventricular tachycardia in rare cases—it should be administered only when a cardiac monitor is being used and a defibrillator is on. 

A lower dose of 3 mg is recommended in persons who have a cardiac transplant or in whom the drug is administered through a central catheter. Adenosine should not be used in patients with bronchospastic lung disease. Common side effects include chest tightness, flushing, and a sense of dread. 

Although intravenous verapamil and diltiazem, which also blocks the AV node, are of potential diagnostic and therapeutic use in narrow complex tachycardia, they may cause [00:08:00] hypotension, and thus are not a first choice in the emergency setting.  

Verapamil can cause 1:1 conduction in AVRT, so could lead to Vfib or ventricular fibrillation. So when, as a provider or a nurse, you don’t know what the type of SVT it is, this is an important drug to avoid. 

Electrical conversion is reserved for patients in unstable condition who are not having a response to adenosine. Antiarrhythmic agents are rarely necessary in the early management of SVT, except for the management of arrhythmias that have caused hemodynamic instability and that have not responded to electrical cardioversion. In these cases, procainamide and ibutilide can be used.  

Geralyn Warfield (host): Our discussion today about PSVT treatments with Jannette Sendin will continue in just one [00:09:00] moment.  

 

Geralyn Warfield (host): Welcome back to our audience as we continue our discussion about treatments for PSVT. Right before the break, Jeannette, you were describing pharmacotherapies for narrow complex tachycardias. Would you be able to describe a little bit more about treatments for wide complex tachycardias?  

Janette Sendin (guest): Absolutely. So, for wide complex tachycardias, adenosine is also useful in the differential diagnosis and treatment of wide complex tachycardias, but it should be given only when these tachycardias are regular, since irregular wide complex tachycardias may be rendered unstable after the administration of adenosine. 

Potential risks include increasing conduction through a bypass tract if the underlying arrhythmia is atrial fibrillation, or terminating the SVT but inducing atrial fibrillation with resultant rapid conduction down a [00:10:00] bypass tract leading to ventricular fibrillation.  

Verapamil and diltiazem should not be administered in patients with wide complex tachycardias since profound hypotension and death may occur. 

Electrical cardioversion is necessary in the treatment of unstable wide complex tachycardias as it is in the treatment of unstable narrow complex tachycardias. Procainamide and ibutilide, as well as lidocaine and amiodarone and sotalol, are useful in the treatment of wide complex tachycardias.  

Stable wide complex irregular tachycardias are usually atrial fibrillation with aberrancy, or the Wolff Parkinson White syndrome. In the case of this arrhythmias, consultation with an expert is generally required.  

Geralyn Warfield (host): So, Jeanette, what types of options are [00:11:00] available for acute therapy?  

Janette Sendin (guest): Yes. Acute therapy, most data on the effectiveness of vagal maneuvers and adenosine for acute termination of tachycardia are derived from mixed populations of SVT. 

Catheter ablation for SVT, in general, and AVNRT in particular, is the current treatment of choice for symptomatic patients because it substantially improves quality of life and reduces cost. A recent randomized clinical trial that compared catheter ablation as first line treatment with antiarrhythmic drugs demonstrated significant benefits in arrhythmia-related hospitalizations. 

The ablation is usually combined with anatomical and mapping approach to the ablation lesions. This approach offers a success rate of 97%, has [00:12:00] a 1.3 to 4% recurrence rate, and has been associated with a risk of AV block of less than 1%. Usually, recurrent recurrences are seen within three months following successful procedure in symptomatic patients who experience frequent episodes of tachycardia, but in the young age, below 18 years old, recurrences may be seen as long as five years post-ablation. 

Geralyn Warfield (host): And how about the types of chronic therapy that are available, Janette?  

Janette Sendin (guest): Yes. Patients with minimal symptoms and short-lived infrequent episodes of tachycardia can be followed up without the need of ablation or long-term pharmacological therapy. Approximately one half of them may become asymptomatic within the next 13 years. 

Chronic administration of antiarrhythmic drugs decreases the frequency and duration of [00:13:00] AVNRT but has a variable success rate in abolishing tachycardia episodes, ranging from 13 percent to 82% and below 20% of patients may discontinue the therapy.  

In view of the excellent success rate and minimal risk of catheter ablation in symptomatic cases, the value of long-term antiarrhythmic drug therapy seems limited, however. 

Geralyn Warfield (host): Janette, you have provided a wide range of information for our listeners today. And in our last segment, could you please focus on current research and novel treatments? 

Janette Sendin (guest): Yes. With the advent of catheter ablation in the 1990s resulting in the successful elimination of accessory pathways in symptomatic patients, AVRT now represents below 20% of all SVTs. 

The [00:14:00] frequency of AVNRT, which used to account for 50% of all SVT cases, has changed to 30%. A rapid evolution of ablation equipment and electrode guiding systems, which has resulted in more controllable and safer procedures. Intracardiac echocardiography, robotic techniques, and sophisticated anatomical navigation systems have been developed. And it is now possible to perform ablation without exposing the operator to radiation and ergonomically unfavorable positions.  

The revolution in computer technology offers not only improved mapping and electrode moving system, but also the enhancement of specific SVT classification schemes with fully automated algorithms that may greatly assist emergency departments, [00:15:00] ambulances, and monitored patients.  

Mapping vests is one of those innovative technologists, where this vest, with disposable electrode, gathers cardiac electrophysiological data from the body surface. A non-invasive 3D mapping system combines the signals with CT scan data to produce and display simultaneous, bi-atrial, and bi-ventricular 3D cardiac maps. 

Cardiac mapping has been an important tool to make ablation safe and effective. The vest has around 250 electrodes and it is like taking an EKG from 250 different places around the chest.  

There are also EKG hardware and software currently available that is compatible with [00:16:00] consumer mobile devices to enable remote heart rhythm monitoring and detection of abnormal heart rhythms or arrhythmias. This can be remotely transmitted to the patient’s provider or cardiologist who can then provide intervention as necessary.  

Another research or study that is ongoing is the medication called etripamil. Etripamil is a nasal spray, a short acting calcium channel blocker, for the rapid termination of paroxysmal supraventricular tachycardia. 

A self-administered product for SVT would give patients the option to safely terminate acute episodes without the need of a hospital visit and potential admission. This approach could empower patients to treat SVT themselves outside of a healthcare setting [00:17:00] and has the potential to reduce the need of additional medical interventions such as intravenous medication given in an acute care setting. 

A study evaluated the safety of etripamil 70 mg nasal spray for the treatment of multiple spontaneous episodes of PSVT over long term period, a median of 7.6 months follow-up. Patients in this study were instructed to perform a vagal maneuver during a suspected episode prior to self-administering etripamil. 

Vagal maneuvers in an at-home setting for resolving SVT episodes resulted to only 2.6%, which is 5 out of 190 patients. Though this is unpublished data, it appears to translate that etripamil is an [00:18:00] innovative method of intervention to effectively terminate SVT from home. We look forward to see further results of this study about etripamil. 

Geralyn Warfield (host): Janette, you have covered quite an array of treatment options from those that are non-pharmacologic to those that are on the horizon for us, and we are so incredibly grateful to you for your time today.  

For our listeners, please don’t forget to listen to the other two episodes in this PSVT mini-series. And for even more information and resources, please check out the episode show notes and visit pcna.net for a related video and more information about this topic.  

Thank you to Milestone Pharmaceuticals for their grant funding for this podcast episode.  

This is your host, Geralyn Warfield, and we will see you next time. 

Thank you for listening to Heart to Heart Nurses. We invite you to visit pcna.net for clinical resources, continuing education, and much more.