The atrioventricular node (AV) measures approximately 1 by 3 by 5 millimeters and sits within an anatomic region bordered anteriorly by septal tricuspid valve annulus, superiorly by the tendon of Todaro and posteriorly by the coronary sinus ostium. This anatomic region is also commonly referred to as the triangle of Koch. The AV node is a subendocardial structure located in the inferior-posterior right atrium. The blood supply to the AV node is from the AV nodal branch of the right coronary artery (90%) or the left circumflex artery (10%) depending on right or left dominant blood supply to the heart. The first septal perforator of the left anterior descending artery also supplies blood to the AV node.
Paroxysmal supraventricular tachycardia (PSVT) accounts for intermittent episodes of supraventricular tachycardia with sudden onset and termination. PSVT is part of the narrow QRS complex tachycardias with a regular ventricular response in contrast to multifocal atrial tachycardia, atrial fibrillation, and atrial flutter. SVTs are classified based on the origin of the rhythm and whether the rhythm is regular or irregular.
Atrial in origin and regular rhythm:
Atrial in origin and irregular rhythm:
AV node in origin and regular rhythm:
AV node in origin and irregular rhythm:
SVT is known to occur in individuals of all ages, but treatment is often difficult. The clinical presentation of SVT is variable- ranging from asymptomatic to severe palpitation. Electrophysiologic studies are usually necessary to determine the pathophysiology of impulse formation and pathways of conduction.
Some of these conditions and medications are listed below:
In the United States, the prevalence of PSVT is approximately 0.2%, and it has an incidence of one to three cases every thousand patients. The most common of the PSVT is atrial fibrillation with a prevalence rate of approximately 0.4% to 1% occurring in men and women equally, it is projected to affect as many as 7.5 million patients by 2050. The risk of developing PSVT was found to be twice in women as compared to men in a population-based study, with the prevalence of the PSVT higher with age. Atrioventricular nodal reentrant tachycardia is found more commonly in patients who are middle-aged or older. Whereas PSVT with an accessory pathway is most common in adolescents, and their occurrence decreases with age.
Besides occurring in healthy people. PSVT can also occur after a myocardial infarction (MI), rheumatic heart disease, mitral valve prolapse, pneumonia, chronic lung disease, and pericarditis. Digoxin toxicity is often associated with PSVT.
PSVT is often due to different reentry circuits in the heart, where less frequent causes include enhanced or abnormal automaticity and triggered activity. Reentry circuits include a pathway within and around the sinus node, within the atrial myocardium, within the atrioventricular node or an accessory pathway involving the atrioventricular node. Different types of PSVT result depending on the existing circuits, and examples are:
Under most circumstances, careful examination in patients with PSVT will show reentry circuits discussed above. No specific histopathologic findings are found in patients with PSVTs secondary to triggered activity and enhanced or abnormal automaticity.
The severity of symptoms in patients with PSVT depends on any underlying structural heart disease, the frequency of PSVT episodes, and the patient's hemodynamic reserve. Usually, patients with PSVT present with symptoms of dizziness, syncope, nausea, shortness of breath, intermittent palpitations, pain or discomfort in the neck, pain or discomfort in the chest, anxiety, fatigue, diaphoresis, and polyuria secondary atrial natriuretic factor secreted mainly by the heart's atria in response to atrial stretch. The most common symptoms are dizziness and palpitations. Patients with PSVT and a known history of coronary artery disease may present with a myocardial infarction secondary to the stress on the heart. Patients with PSVT and a known history of heart failure may come in with acute exacerbation. Frequent PSVTs in a patient can result in new-onset of heart failure secondary to tachycardia-induced cardiomyopathy.
A detailed history of the patient with PSVT should include past medical and cardiac history, time of symptom onset, prior episodes, and treatments. The patients' current medication list must be obtained. Investigations of involvement in physical activities such as exercise or outdoor sports should be made, as patients who have symptomatic PSVT's avoid such hobbies. Patients presenting with PSVTs should get a thorough physical exam, including vital signs (respiratory rate, blood pressure, temperature, and heart rate) to help assess their hemodynamic stability.
A significant component of evaluation for a patient who presents with signs and symptoms of PSVT is history and physical exam. These should include vital signs (respiratory rate, blood pressure, temperature, and heart rate), review of the patient's medication list, and a 12-lead electrocardiogram. During an evaluation, a health care provider should establish if the patient is hemodynamically stable and whether they have any underlying ischemic heart disease or heart failure. Digoxin toxicity should be ruled out.
Healthcare providers should consider thyroid function testing, pulmonary function testing, including routine blood work, and echocardiography as part of their initial evaluation of patients presenting with symptomatic PSVTs.
Treatment of PSVT in a patient is dependent on the type of rhythm present on the electrocardiogram and the patient's hemodynamic stability. Patients presenting with hypotension, shortness of breath, chest pain, shock, or altered mental status are considered hemodynamically unstable, and their electrocardiogram evaluation must be done to determine if they are in sinus rhythm or not. If they are not in sinus rhythm, these patients should undergo urgent cardioversion. If they are determined to be in appropriate sinus tachycardia, then their underlying etiology must be treated. For any manifestations of cardiac ischemia, intravenous beta-blockers should be considered. If they have inappropriate sinus tachycardia on the electrocardiogram and are determined to be hemodynamically unstable, treatment with intravenous beta-blockers may be appropriate.
If on the initial evaluation, a patient is to found to be hemodynamically stable, then the treatment of the patient depends on the specific PSVT present on the electrocardiogram. If the 12-lead electrocardiogram shows that the rhythm is irregular and P waves are absent, then the patient should be appropriately treated for atrial fibrillation. If the rhythm on the electrocardiogram is irregular and flutter waves are present, then the patient should be treated for atrial flutter. If the rhythm on the electrocardiogram is irregular and multiple P wave morphologies are present, then the patient should be treated for multifocal atrial tachycardia.
In patients who are hemodynamically stable and showing a regular rhythm with visible P waves on the electrocardiogram, then an assessment of the atrial rate, the relationship between the atrial and ventricular pacing, P-wave morphology and the P-wave position in the rhythm cycle is required. Type of PSVT present (atrial tachycardia, multifocal atrial tachycardia, atrial flutter, atrial flutter with a variable block, intra-atrial reentrant tachycardia, sinus tachycardia, sinoatrial node reentrant tachycardia, atrioventricular nodal reentrant tachycardia, atrioventricular reciprocating tachycardia, junctional ectopic tachycardia, and nonparoxysmal junctional tachycardia) determines the treatment.
In patients who are hemodynamically stable and have an electrocardiogram that shows a regular rhythm with undetectable P waves, Valsalva maneuvers, carotid sinus massage, or intravenous adenosine might be used to slow the ventricular rate or convert the rhythm into sinus rhythm and thus aid in the diagnosis. In some instances, increasing the electrocardiogram paper speed from 25 mm per second to 50 mm per second might help as well. If intravenous adenosine does not work, then intravenous or oral calcium channel blockers or beta-blockers should be used. Patients with PSVTs must also undergo evaluation for any underlying pre-excitation syndrome, and patients who fail medical treatment or those who might need radiofrequency catheter ablation need cardiology consultation.
In cases with no structural heart disease, the prognosis of PSVT is reasonably good. For patients with structural heart disease, the prognosis is often guarded. The arrhythmia may come on suddenly and last anywhere from a few seconds to several days. Most patients develop anxiety, a sense of doom, and others may develop hemodynamic compromise. The arrhythmia can result in congestive heart failure, myocardial infarction, and pulmonary edema.
If not identified promptly symptomatic complications such as syncope, fatigue, or dizziness can occur.
Educating patients at risk for this rhythm and making a closed-loop communication between them and their providers can help further improve the management of these rhythms. If available, patient education should be provided using resources familiar to the patient including online resources and pamphlets.
Frequent PSVT can result in tachycardia-induced cardiomyopathy, a study on pregnant females found that PSVT in the first to second gestational month increase the chances of the child developing ostium secundum atrial septal defect.
Treatment of PSVT can involve an interprofessional team, including emergency department physicians and nurses, cardiologists and cardiology nurses, primary care providers, and pharmacists. Emergency medical technicians are often the first to encounter patients and provide treatment. The team should evaluate, as outlined above. Nurses, pharmacists, and physicians can provide education. Pharmacists should educate patients about medication side effects and compliance, as well as checking for drug interactions. [Level 5]
|||Arterial blood supply of the atrioventricular node and main bundle., Van der Hauwaert LG,Stroobandt R,Verhaeghe L,, British heart journal, 1972 Oct [PubMed PMID: 5086972]|
|||Anatomical aspects of the arterial blood supply to the sinoatrial and atrioventricular nodes of the human heart., Pejković B,Krajnc I,Anderhuber F,Kosutić D,, The Journal of international medical research, 2008 Jul-Aug [PubMed PMID: 18652764]|
|||Arterial supply to sinuatrial and atrioventricular nodes: imaging with multidetector CT., Saremi F,Abolhoda A,Ashikyan O,Milliken JC,Narula J,Gurudevan SV,Kaushal K,Raney A,, Radiology, 2008 Jan [PubMed PMID: 18024438]|
|||Clinical importance of Koch's triangle size in children: a study using 3-dimensional electroanatomical mapping., Sumitomo N,Tateno S,Nakamura Y,Ushinohama H,Taniguchi K,Ichikawa R,Fukuhara J,Abe O,Miyashita M,Kanamaru H,Ayusawa M,Harada K,Mugishima H,, Circulation journal : official journal of the Japanese Circulation Society, 2007 Dec [PubMed PMID: 18037746]|
|||Koch's triangle sized up: anatomical landmarks in perspective of catheter ablation procedures., Inoue S,Becker AE,, Pacing and clinical electrophysiology : PACE, 1998 Aug [PubMed PMID: 9725153]|
|||Supraventricular tachycardia., Ganz LI,Friedman PL,, The New England journal of medicine, 1995 Jan 19 [PubMed PMID: 7800009]|
|||Supraventricular tachycardia., Chauhan VS,Krahn AD,Klein GJ,Skanes AC,Yee R,, The Medical clinics of North America, 2001 Mar [PubMed PMID: 11233946]|
|||Atrioventricular nodal reentry. Clinical, electrophysiological, and therapeutic considerations., Akhtar M,Jazayeri MR,Sra J,Blanck Z,Deshpande S,Dhala A,, Circulation, 1993 Jul [PubMed PMID: 8319342]|
|||Demonstration of dual atrioventricular nodal pathways in man., Rosen KM,Mehta A,Miller RA,, The American journal of cardiology, 1974 Feb [PubMed PMID: 4810028]|
|||Mechanisms of cardiac arrhythmias., Waldo AL,Wit AL,, Lancet (London, England), 1993 May 8 [PubMed PMID: 8098085]|
|||Classification of supraventricular tachycardias., Klein GJ,Sharma AD,Yee R,Guiraudon GM,, The American journal of cardiology, 1987 Aug 31 [PubMed PMID: 3630922]|
|||Enhanced diagnosis of narrow complex tachycardias with increased electrocardiograph speed., Accardi AJ,Miller R,Holmes JF,, The Journal of emergency medicine, 2002 Feb [PubMed PMID: 11858914]|
|||Supraventricular tachycardia: implications for the intensivist., Trohman RG,, Critical care medicine, 2000 Oct [PubMed PMID: 11055681]|
|||Characteristics of accessory pathways exhibiting decremental conduction., Murdock CJ,Leitch JW,Teo WS,Sharma AD,Yee R,Klein GJ,, The American journal of cardiology, 1991 Mar 1 [PubMed PMID: 1998282]|
|||Paroxysmal supraventricular tachycardia in the general population., Orejarena LA,Vidaillet H Jr,DeStefano F,Nordstrom DL,Vierkant RA,Smith PN,Hayes JJ,, Journal of the American College of Cardiology, 1998 Jan [PubMed PMID: 9426034]|
|||Influence of age and gender on the mechanism of supraventricular tachycardia., Porter MJ,Morton JB,Denman R,Lin AC,Tierney S,Santucci PA,Cai JJ,Madsen N,Wilber DJ,, Heart rhythm, 2004 Oct [PubMed PMID: 15851189]|
|||Analysis of age of onset of accessory pathway-mediated tachycardia in men and women., Tada H,Oral H,Greenstein R,Pelosi F Jr,Knight BP,Strickberger SA,Morady F,, The American journal of cardiology, 2002 Feb 15 [PubMed PMID: 11835934]|
|||Clinical differentiation of narrow QRS complex tachycardias., Xie B,Thakur RK,Shah CP,Hoon VK,, Emergency medicine clinics of North America, 1998 May [PubMed PMID: 9621846]|
|||Inappropriate sinus tachycardia: evaluation and therapy., Krahn AD,Yee R,Klein GJ,Morillo C,, Journal of cardiovascular electrophysiology, 1995 Dec [PubMed PMID: 8720214]|
|||The role of triggered activity in clinical ventricular arrhythmias., Brugada P,Wellens HJ,, Pacing and clinical electrophysiology : PACE, 1984 Mar [PubMed PMID: 6200854]|
|||Clinical practice. Evaluation and initial treatment of supraventricular tachycardia., Link MS,, The New England journal of medicine, 2012 Oct 11 [PubMed PMID: 23050527]|
|||Supraventricular tachycardia: diagnosis and management., Fox DJ,Tischenko A,Krahn AD,Skanes AC,Gula LJ,Yee RK,Klein GJ,, Mayo Clinic proceedings, 2008 Dec [PubMed PMID: 19046562]|
|||Electrophysiologic evaluation of supraventricular tachycardia., Josephson ME,Wellens HJ,, Cardiology clinics, 1997 Nov [PubMed PMID: 9403161]|
|||Supraventricular tachycardia. ECG diagnosis and anatomy., Obel OA,Camm AJ,, European heart journal, 1997 May [PubMed PMID: 9152669]|
|||Contemporary management of paroxysmal supraventricular tachycardia., Ferguson JD,DiMarco JP,, Circulation, 2003 Mar 4 [PubMed PMID: 12615783]|
|||Supraventricular tachycardia: mechanisms and management., Josephson ME,Kastor JA,, Annals of internal medicine, 1977 Sep [PubMed PMID: 332025]|
|||Current role of pharmacologic therapy for patients with paroxysmal supraventricular tachycardia., Basta M,Klein GJ,Yee R,Krahn A,Lee J,, Cardiology clinics, 1997 Nov [PubMed PMID: 9403162]|
|||Narrow QRS complex tachycardias., Pieper SJ,Stanton MS,, Mayo Clinic proceedings, 1995 Apr [PubMed PMID: 7898144]|
|||Using the right drug: a treatment algorithm for regular supraventricular tachycardias., Lévy S,Ricard P,, European heart journal, 1997 May [PubMed PMID: 9152672]|
|||ACC/AHA/ESC guidelines for the management of patients with supraventricular arrhythmias--executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for the Management of Patients With Supraventricular Arrhythmias)., Blomström-Lundqvist C,Scheinman MM,Aliot EM,Alpert JS,Calkins H,Camm AJ,Campbell WB,Haines DE,Kuck KH,Lerman BB,Miller DD,Shaeffer CW Jr,Stevenson WG,Tomaselli GF,Antman EM,Smith SC Jr,Alpert JS,Faxon DP,Fuster V,Gibbons RJ,Gregoratos G,Hiratzka LF,Hunt SA,Jacobs AK,Russell RO Jr,Priori SG,Blanc JJ,Budaj A,Burgos EF,Cowie M,Deckers JW,Garcia MA,Klein WW,Lekakis J,Lindahl B,Mazzotta G,Morais JC,Oto A,Smiseth O,Trappe HJ,, Circulation, 2003 Oct 14 [PubMed PMID: 14557344]|
|||Effectiveness of the Valsalva Manoeuvre for reversion of supraventricular tachycardia., Smith GD,Dyson K,Taylor D,Morgans A,Cantwell K,, The Cochrane database of systematic reviews, 2013 Mar 28 [PubMed PMID: 23543578]|
|||Oral verapamil in paroxysmal supraventricular tachycardia recurrence control: a randomized clinical trial., Shaker H,Jahanian F,Fathi M,Zare M,, Therapeutic advances in cardiovascular disease, 2015 Feb [PubMed PMID: 25297337]|
|||Radiofrequency catheter ablation of atrial arrhythmias. Results and mechanisms., Lesh MD,Van Hare GF,Epstein LM,Fitzpatrick AP,Scheinman MM,Lee RJ,Kwasman MA,Grogin HR,Griffin JC,, Circulation, 1994 Mar [PubMed PMID: 8124793]|
|||Differential diagnosis of regular, narrow-QRS tachycardias., Katritsis DG,Josephson ME,, Heart rhythm, 2015 Jul [PubMed PMID: 25828600]|
|||Differentiation of paroxysmal narrow QRS complex tachycardias using the 12-lead electrocardiogram., Kalbfleisch SJ,el-Atassi R,Calkins H,Langberg JJ,Morady F,, Journal of the American College of Cardiology, 1993 Jan [PubMed PMID: 8417081]|