Wolff-Parkinson-White Syndrome and its Connection to Paroxysmal Supraventricular Tachycardia

This is a recent research paper I wrote for my medical terminology class at my local community college. It was inspired by my childhood heart condition. I learned some interesting things!

Abstract

This paper is an endeavor borne of curiosity and personal experience to explore the connection between episodes of Paroxysmal Supraventricular Tachycardia and the underlying existence of Wolff-Parkinson-White Syndrome. History, symptoms, diagnosis, temporary and long-term treatment, and prognosis of WPW Syndrome are researched and described in this paper with the purpose of informing.

 

 

 

 

 

Wolff-Parkinson-White Syndrome and its Connection to Paroxysmal Supraventricular Tachycardia

     Most parents would find it startling if their baby, young child, or adolescent suddenly died from an unexplained heart complication. These people would seek answers, desire closure, and probably ask, “What should/could we have done differently?” In 1930, a condition was described by Drs. Wolff, Parkinson and White, which became the new focus in the world of cardiology at the time, and has peaked the interests of cardiac medical professionals ever since: Wolf-Parkinson-White syndrome (Scheinman, 2012, pp. 1-2). Very simply, it is a condition of the heart in which abnormal electrical pathways or “wires” are present, creating a “short-circuiting” which triggers an episode of paroxysmal supraventricular tachycardia, a rapid heart rate above 100 beats per minute. This condition occurs most commonly in children, adolescents, or young adults, and is treatable. In rare cases, if left untreated Wolff-Parkinson-White syndrome has been known to result in sudden death (Weitz, 2013).

      In order to understand this unique and potentially devastating condition, it would be helpful to first understand the history of its discovery as well as notable medical advances in treating it. As mentioned above, it was in 1930 when Drs. Wolff, Parkinson and White first provided a thorough description of this perplexing syndrome, thus giving them the credit for the name. On the tail of their research, Pick, Langendorf and Katz studied EKG’s of patients with this condition and were able to use deductive analysis of those EKG’s in order to gain a clearer understanding of what happens on a physiological level in the heart during an episode of paroxysmal supraventricular tachycardia (PSVT, or more simply, SVT). Their findings were confirmed by Wellens and Durrer who used electrical stimulation of the heart. With this newfound knowledge, doctors at Duke University Medical Center were able to surgically divide the accessory pathways which triggered the episodes of tachycardia in these patients. In 1981, Morady and Scheinman were able to ablate an accessory pathway using high-energy direct-current shocks, providing the first successful therapy to a patient with WPW syndrome (Wolff-Parkinson-White syndrome), preventing further episodes of PSVT. This opened the popular gateway to successful and realistic treatment in patients with this condition. Ever since that discovery, the world of cardiology has never been the same (Scheinman, 2012, pp. 1-2).

    Before discussing signs and symptoms of this condition, two items must first be described: the abnormalities in a heart with Wolff-Parkinson-White syndrome, and what happens in the heart during an episode of Paroxysmal Supraventricular Tachycardia. WPW syndrome is the second most common cause of PSVT (Matthews, 2013).Wolff-Parkinson-White syndrome is caused by the malformation of the heart while the child is still in the womb. The cause of this is unknown, but current research is leaning towards identifying a gene that is likely responsible for this condition. In a normal heart, electrical impulses begin in the sinoatrial node which is the heart’s natural pacemaker (located in the wall of the right atrium). This impulse stimulates both of the atria to contract. The impulse is slowed, then, by the AV node, allowing the ventricles time to fill with the blood just pumped from the atria, and then they too contract (Schueler, Beckett, & Gettings, 2011). In the heart of a patient with WPW syndrome, the electrical impulses that stimulate the heart muscles to contract are mal-directed via extra pathways called “accessory pathways,” which cross from the atria to the ventricles, thereby bypassing the AV node (Almendral, 2012; Fisher, 2013). When an accessory pathway is used for conduction of the electrical impulse, it can then push the patient into an episode of PSVT, also known as pre-excitation syndrome, when the ventricles quickly contract before they are filled with blood. The electrical impulse then travels in a circular motion via the accessory pathway rather than ending in order to allow the SA node to produce a new impulse. A “pounding” sensation and rapid pulse are generally the first signs that this has occurred. (“Wolff-Parkinson-White Syndrome,” 2012). Below is a diagram of a normal heart and a heart demonstrating tachycardia via an accessory pathway:

wolff-parkinson-white-lg-enlg

                                                (Wolff-Parkinson-White Syndrome, n.d.).

Fortunately, there are both temporary and long-term treatments to normalize this condition.

     Generally speaking, when a person has WPW syndrome, he or she is not likely to know about it until an episode of PSVT occurs or another symptom of a cardiac abnormality such as chest tightness, pain, shortness of breath, or anxiety presents itself. Other symptoms of PSVT include dizziness, syncope (fainting), palpitations (pounding, thumping, or racing sensation), and a fast pulse (Link 2012). These symptoms must be immediately addressed.

     Temporary treatment for Wolff-Parkinson-White syndrome usually revolves around addressing the episodes of paroxysmal supraventricular tachycardia rather than correcting the abnormalities in the heart itself. The first things most physicians will recommend for a patient with PSVT are vagal maneuvers. These actions sometimes have the effect of stimulating the vagus nerve which can then slow the electrical impulses that run through the AV node. Gagging, completing the Valsava maneuver (bearing down, as though to complete a bowel movement), immersing the face in cold water, and coughing are simple techniques that could potentially correct the heart rate (Link, 2012). Physicians in the emergency room may perform a carotid sinus massage on young patients, though with older patients, this is considered to be a high risk maneuver which could be more likely to result in a stroke. (“Vagal Maneuvers for a Fast,” 2010). If all of these maneuvers fail, chemical or external cardioversion (restoring the heart to a normal rhythm) will need to be performed. Amiodarone or adenosine (Adenocard or Adenoscan) is typically given intravenously with the purpose of quickly stopping the electrical impulses through the AV node, essentially “restarting” the heart, allowing it to return to a normal rhythm. Adenosine lasts for approximately one minute and has several common side effects that the patient is likely to experience: flushing of skin, shortness of breath, headache, nausea, and chest pain or pressure (“Adenosine for Fast Heart,” 2010). In rare cases, adenosine fails to correct the heart rhythm in a patient with WPW syndrome, and external cardioversion will need to be performed with the use of a defibrillator. External defibrillation delivers a DC current electrical shock to the heart, causing the cardiac cells to briefly depolarize, giving the SA node enough time to resume its job as the normal pacemaker of the heart. This works well with WPW patients because the circuit using the accessory pathway gets interrupted by the current delivered during defibrillation. (Beinart, 2013). Unfortunately, as mentioned above, all of these treatments are simply temporary and do not correct the root problem: the existence of abnormalities in the heart itself.

     Long-term treatments will need to be given for WPW syndrome in order for the patient to have a high-likelihood of living a healthy life. Beta blockers, calcium channel blockers or antiarrhythmic medications may be prescribed to be taken orally with the purpose of maintaining normal heart rhythm. Another alternative treatment would be to perform a radiofrequency catheter ablation, a choice that most patients prefer, and which has a high success rate. Occasionally, due to complications that occur during the catheter ablation, a patient may have to have a pacemaker installed in order to maintain normal heart rhythm. Because of its high success rate (95%) most patients with Wolff-Parkinson-White syndrome opt to have the catheter ablation, so this process will be discussed in greater detail (Knight, 2013). (Fisher, 2013).

     The process of successfully completing a radiofrequency catheter ablation has several important steps, beginning in pre-op. The night before surgery, the patient should not consume any food nor take his heart rhythm medications. This will be crucial during surgery, when the doctors try to trigger the heart to beat abnormally in order to identify the location(s) of the accessory pathway(s). The morning of the surgery, an IV will be started and blood will be drawn for analysis. Women will have a pregnancy test performed to ensure they are not with child. EKG electrodes will be attached to the chest as well as one large electrode on both the chest and back, to be used during the ablation itself and also for external defibrillation that, in rare cases, may be needed during surgery if doctors are unable to restore normal heart rhythm in the patient. Because catheters will be inserted into the femoral artery, the leg will be shaved and swabbed with an alcohol wipe. The neck will also be wiped clean. Some patients who are awake during surgery will then be sedated; otherwise, the anesthesiologist will provide the correct amounts of medications to put the patient entirely under. A ventilator may be needed for respiration during this time. The doctors can then proceed forward with the ablation, which takes place under a giant x-ray tube. (Fisher 2013).

     Several catheters with one-way valves (to prevent bleeding out) are then inserted in the leg(s) and/or neck which are pushed to the heart with the visualization that the x-ray provides. The doctors study the heart’s normal activity and then, with the assistance of a computer, attempt to initiate an episode of PSVT. If the computer is unable to assist with this process, a medication may be given to increase the heart rate (Miyazaki, 2012 p. 1144). The doctors then explore how to stop the heart’s abnormal rhythm. This allows doctors to locate where the accessory pathway is located. When this “study phase” is complete, wires are inserted into the catheters. A blood thinner is generally given as a preventative measure. The wires have a special tip on them that allow them to become very hot to destroy the accessory pathways, although this process can also cause the blood to clot. Radiofrequency waves are applied to the patch on the patient’s back that travel through the body to the ablation wire which then quickly increases in temperature. If placed properly, the wire will incinerate the accessory pathway, rendering it useless in the conduction of the electrical impulses in the heart. (Fisher 2013).

      The doctors repeat some of the earlier study procedures on the heart, seeing if they can trigger the heart to jump into another episode of PSVT. If they are able to do so, the wire is positioned at the location of the next accessory pathway and the procedure is repeated. However, if they are unable to trigger another episode, the patient is sent to a lab where they are carefully observed for about half an hour, during which they test one more time to see if they can create a tachycardia in the heart. At this point, if all is well, a counter-agent is given to reverse the action of the blood thinner, the wires are removed, and bandages with significant pressure are applied to the wound sites. These sites are considered “high-risk” for the first 4-6 hours, and the patient must lie very still. During this time, he is being observed for complications arising from blood clots or heart abnormalities that could be a direct result from the surgery. The entire procedure takes approximately 2-5 hours depending on the number of accessory pathways and complications that arise. During an uncomplicated catheter ablation, the patient can usually return home the same day with no other symptoms besides fatigue and pain at the catheter insertion sites. (Fisher 2013).

     Any procedure has risks involved, and this procedure is no different. A possible complication of a radiofrequency catheter ablation that approximately 3% of people who undergo this surgery face is damage to the AV node itself (called a “complete heart block), which means that the heart is no longer able to conduct electrical impulses properly and would then be dependent on a pacemaker. If this occurs during the surgery, everything quickly changes and the patient would then have open heart surgery so the pacemaker could be installed. Another complication is that not all the accessory pathways are able to be ablated via catheter insertion for varying reasons and so the patient would have to undergo a second surgery where the chest cavity is opened up so the heart is more accessible for the cardiologist. The second procedure is repeated without the use of the catheters with the purpose of destroying the accessory pathways. Other complications are bleeding at the sites of catheter insertion, deep venous thrombosis, development of a fistula in the leg, perforation or other trauma to the heart, stroke, infection, injury to the femoral nerve, and allergic reactions to medications used in the procedure. In patients where catheters are also inserted in the neck or just below the clavicle, perforation of a lung is a risk. Of course, the x-ray used to guide the wire to the heart could potentially put the patient at risk for skin damage. If this procedure is performed in a competent and highly-trained cardiology center, the total risk for these complications occurring is approximately 1.5%. In very rare cases, the patient may die as a complication of a radiofrequency catheter ablation. (Fisher 2013).

     The prognosis for Wolff-Parkinson-White syndrome is good, and although geneticists are still unable to identify the gene responsible for its cause, both temporary and long-term treatments more than suffice to give a patient with this condition a relatively normal and healthy life. In fact, many people find that the treatment options available, such as the radiofrequency catheter ablation, are so successful that they never notice another heart problem again. This is certainly not a condition that parents need to fear if their child is diagnosed with it, and a person who has this condition needn’t sorrow. Modern treatments have paved the path to healing. Diagnosis with Wolff-Parkinson-White syndrome can instead be a beautiful reminder about the fragility of life, the intricate and innate beauty and complexity of the inner workings of the human body, and the mental power and exploring curiosity of the great minds of healthcare workers, engineers, and creative thinkers who have made treatment for this condition a success.    

 

 

 

References

Adenosine for fast heart rates. (2010, August 9). Retrieved December 3, 2013, from Web MD website: http://www.webmd.com/heart-disease/adenosine-for-fast-heart-rates

Almendral, J., Castellanos, E., & Ortiz, M. (2012). Update: Arrhythmias (V). Paroxysmal supraventricular tachycardias and preexcitation syndromes. Revista Española De Cardiología (English Ed.), 65(5), 456-469. doi:10.1016/j.recesp.2011.11.026

Beinart, S. C. (2013, June 26). Synchronized electrical cardioversion (J. N. Rottman, Ed.). Retrieved December 3, 2013, from Medscape website: http://emedicine.medscape.com/article/1834044-overview

Davis, C. P. (2012, February 27). Supraventricular tachycardia (SVT, PSVT) (W. C. Shiel, Jr., Ed.). Retrieved November 29, 2013, from http://www.emedicinehealth.com/supraventricular_tachycardia/page8_em.htm

Fisher, W. G. (2013, October 6). Catheter ablation for supraventricular tachycardias. Retrieved December 3, 2013, from http://www.medtees.com/wpwablation.html

Knight, B. P. (2013, May 13). Patient information: Wolff-Parkinson-White syndrome (beyond the basics) (S. Lévy & B. C. Downey, Ed.). Retrieved December 4, 2013, from Up To Date website: http://www.uptodate.com/contents/wolff-parkinson-white-syndrome-beyond-the-basics?source=see_link

Link, M. (2012). Clinical practice. Evaluation and initial treatment of supraventricular tachycardia. The New England Journal Of Medicine, 367(15), 1438-1448. doi:10.1056/NEJMcp1111259

Matthews, R. J. (2013, April 27). The Wolff-Parkinson-White syndrome. Retrieved November 29, 2013, from http://www.rjmatthewsmd.com/Definitions/wolff_parkinson_white_syndrome.htm

Miyazaki, S., Taniguchi, H., Koura, K., Uchiyama, T., Takayama, K., Kusa, S., & Iesaka, Y. (2012). Supraventricular tachycardia: what is the mechanism? Journal Of Cardiovascular Electrophysiology, 23(10), 1144-1145. doi:10.1111/j.1540-8167.2011.02256.x

Scheinman, M. M., M.D. (2012). The History of the Wolff–Parkinson–White Syndrome [Abstract]. Rambam Maimonides Medical Journal. http://dx.doi.org/10.5041/RMMJ.10083

Schueler, S. J., Beckett, J. H., & Gettings, D. S. (2011, January 7). Wolff Parkinson White syndrome: Anatomy. Retrieved November 30, 2013, from FreeMD website: http://www.freemd.com/wolff-parkinson-white-syndrome/anatomy.htm

Vagal maneuvers for a fast heart rate. (2010, August 9). Retrieved December 3, 2013, from Web MD website: http://www.webmd.com/a-to-z-guides/vagal-maneuvers-for-a-fast-heart-rate-topic-overview

Weitz, D. (2013, September 16). Wolff-Parkinson-White syndrome (WPW syndrome) (W. C. Shiel, Jr. & D. L. Kulick, Ed.). Retrieved November 29, 2013, from MedicineNet.com website: http://www.medicinenet.com/wolff-parkinson-white_syndrome/article.htm

Wolff-Parkinson-White syndrome [Illustration]. (n.d.). Mayo Clinic. Retrieved from http://www.mayoclinic.org/wolff-parkinson-white/enlargeimage2572.html

Wolff-Parkinson-White syndrome. (2012, June 4). In A.D.A.M. Medical Encyclopedia. Retrieved November 30, 2013, from http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001206/

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