Editing Tetralogy of Fallot (section)

== Treatment ==

=== Tet spells ===
Tet spells are defined as cyanotic spells occurring due to the obstruction right ventricular outflow.<ref>{{cite journal | vauthors = Wu IL, Tseng JC | title = Pulmonary embolism in a patient of tetralogy of Fallot: a diagnostic challenge | journal = The American Journal of Emergency Medicine | volume = 33 | issue = 6 | pages = 865.e5–865.e6 | date = June 2015 | pmid = 25619873 | doi = 10.1016/j.ajem.2014.12.061 }}</ref> Tet spells can be triggered by various factors such as crying, [[Tachypnea|progressive tachypnea]], and deep breathing, with symptoms including but not limited to blue skin, nails and lips, profound crying and difficulty breathing.<ref>{{Cite journal|vauthors=Gawalkar AA|date=December 3, 2021|title=Management of Tet Spell – an updated Review|url=https://www.corpuspublishers.com/assets/articles/article-pdf-253.pdf|journal=Current Research in Emergency Medicine |volume=1|issue=1|pages=1–2 |doi=10.54026/CREM/1002 |s2cid=248489949 |access-date=December 3, 2021|archive-date=December 3, 2021|archive-url=https://web.archive.org/web/20211203163442/https://www.corpuspublishers.com/assets/articles/article-pdf-253.pdf|url-status=live}}</ref>

Tet spells may be treated with [[beta-blockers]] such as [[propranolol]], but acute episodes require rapid intervention with [[morphine]] or intranasal [[fentanyl]]<ref>{{cite journal | vauthors = Tsze DS, Vitberg YM, Berezow J, Starc TJ, Dayan PS | title = Treatment of tetralogy of Fallot hypoxic spell with intranasal fentanyl | journal = Pediatrics | volume = 134 | issue = 1 | pages = e266–e269 | date = July 2014 | pmid = 24936003 | doi = 10.1542/peds.2013-3183 | s2cid = 2996572 }}</ref> to reduce ventilatory drive, a vasopressor such as [[phenylephrine]], or [[norepinephrine]] to increase systemic vascular resistance, and IV fluids for volume expansion.<ref name="Munoz_2010" />{{rp|18, 201}}

Oxygen (100%) may be effective in treating spells because it is a potent pulmonary vasodilator and systemic vasoconstrictor. This allows more blood flow to the lungs by decreasing shunting of deoxygenated blood from the right to left ventricle through the VSD. There are also simple procedures such as [[squatting position|squatting]] and the knee chest position which increase systemic vascular resistance and decrease right-to-left shunting of deoxygenated blood into the systemic circulation.<ref name="Munoz_2010" />{{rp|18, 201}}<ref name="Squatting: the hemodynamic change i"/>

If the spells are refractory to the above treatments, people are usually intubated and sedated. The treatment of last resort for tet spells is [[extracorporeal membrane oxygenation]] (ECMO) along with consideration of Blalock-Thomas-Taussig shunt (BTT shunt).<ref name="Munoz_2010" />{{rp|18, 201}}

=== Total surgical repair ===
Total surgical repair of TOF is a curative surgery. Different techniques can be used in performing TOF repair. One method to permit pulmonary blood flow post-birth is the stenting of the ductus arterious (DA) through the inducement of a systemic-to-pulmonary shunt. This surgical approach has an 83% success rate. <ref>{{cite journal |last1=van der Ven |first1=Jelle P.G. |last2=van den Bosch |first2=Eva |last3=Bogers |first3=Ad J.C.C |last4=Helbing |first4=Willem A. |title=Current Outcomes and Treatment of Tetralogy of Fallot |journal=F1000Research |date=2019 |volume=8 |pages=F1000 Faculty Rev-1530 |doi=10.12688/f1000research.17174.1|doi-access=free |pmid=31508203 |pmc=6719677 }}</ref> However, a transatrial, transpulmonary artery approach is used for most cases.<ref name = "Mavroudis_2015">{{cite book| vauthors = Mavroudis C, Backer CL, Idriss RF |title=Atlas of pediatric cardiac surgery |isbn=9781447153191|location=London |oclc=926915143 |date=2015}}</ref>{{rp|153}} The repair consists of two main steps: closure of the VSD with a patch and reconstruction of the right ventricular outflow tract.<ref name="Corno_2009" />

This open-heart surgery is designed to relieve the right ventricular outflow tract stenosis by careful [[Segmental resection|resection]] of muscle and to repair the VSD.<ref name = "Mavroudis_2015" />{{rp|154}}The right ventricle outflow tract can be reconstructed using mainly 2 procedures: a transannular patch (TAP) or a pulmonary valve-sparing procedure (PVS). The decision on the type of the procedure depends on individual anatomy (especially the size of the pulmonary valve). PVS showed better overall survival, event-free survival and less pulmonary regurgitation at 10, 20 and 30 years after the operation.  PVS  can be performed with or without [[Ventriculotomy (cardiac)|ventriculotomy]]. A study found similar overall and event-free survival and pulmonary regurgitation rate between patients who underwent PVS with ventriculotomy and the ones who did not.<ref>{{Cite journal |last1=Ono |first1=Yoshikazu |last2=Hoashi |first2=Takaya |last3=Imai |first3=Kenta |last4=Okuda |first4=Naoki |last5=Komori |first5=Motoki |last6=Kurosaki |first6=Kenichi |last7=Ichikawa |first7=Hajime |date=2022-03-01 |title=Impact of right ventriculotomy for tetralogy of Fallot repair with a pulmonary valve–sparing procedure |url=https://www.jtcvsopen.org/article/S2666-2736(22)00005-5/abstract |journal=JTCVS Open |language=English |volume=9 |pages=191–205 |doi=10.1016/j.xjon.2021.10.061 |pmid=36003424 |pmc=9390402 |issn=2666-2736}}</ref>

Additional reparative or reconstructive surgery may be done on patients as required by their particular cardiac anatomy.<ref name="Mavroudis_2015" />{{rp|153}} 

Timing of surgery in asymptomatic patients is usually between the ages of two months to one year.<ref name="Munoz_2010" />{{rp|201–202}} However, in symptomatic patients showing worsening blood oxygen levels, severe tet-spells (cyanotic spells), or dependence on prostaglandins from early neonatal period (to keep the ductus arteriosus open) need to be planned fairly urgently<ref name="Munoz_2010" />{{rp|201–202}}

Potential surgical repair complications include residual ventricular septal defect, residual outflow tract obstruction, complete atrioventricular block, arrhythmias, aneurysm of right ventricular outflow patch, and pulmonary valve insufficiency.<ref name="Corno_2009" />{{rp|59}} Long-term complications most commonly include pulmonary valve regurgitation, and arrhythmias.<ref name="Chessa_2012" /> Adults with repaired TOF require lifelong surveillance to monitor for such complications, with frequency of monitoring varying according to age, diagnostic methods, and the severity of the condition. <ref>{{Cite journal |last1=Geva |first1=Tal |last2=Wald |first2=Rachel M. |last3=Bucholz |first3=Emily |last4=Cnota |first4=James F. |last5=McElhinney |first5=Doff B. |last6=Mercer-Rosa |first6=Laura M. |last7=Mery |first7=Carlos M. |last8=Miles |first8=Andrea Leann |last9=Moore |first9=Jeremy |last10=on behalf of the American Heart Association Council on Lifelong Congenital Heart Disease and Heart Health in the Young; Council on Cardiovascular Surgery and Anesthesia; Council on Clinical Cardiology; and Council on Cardiovascular and Stroke Nursing |date=2024-11-21 |title=Long-Term Management of Right Ventricular Outflow Tract Dysfunction in Repaired Tetralogy of Fallot: A Scientific Statement From the American Heart Association |url=https://www.ahajournals.org/doi/10.1161/CIR.0000000000001291 |journal=Circulation |volume=150 |issue=25 |pages=e689–e707 |language=en |doi=10.1161/CIR.0000000000001291 |pmid=39569497 |issn=0009-7322|url-access=subscription }}</ref>

Total repair of tetralogy of Fallot initially carried a high mortality risk, but this risk has gone down steadily over the years. Surgery is now often carried out in infants one year of age or younger with less than 5% perioperative mortality.<ref name="Munoz_2010" />{{rp|205}} Post surgery, most patients enjoy an active life free of symptoms.<ref name="Munoz_2010" />{{rp|205}} Currently, long-term survival is close to 90%.<ref name="Munoz_2010" />{{rp|167}} Today the adult TOF population continues to grow and is one of the most common congenital heart defects seen in adult outpatient clinics.<ref name="Roos-Hesselink_2017" />{{rp|100–101}}   

=== Palliative surgery ===
Initially surgery involved forming a side to end [[surgical anastomosis|anastomosis]] between the [[subclavian artery]] and the [[pulmonary artery]] -i.e. a systemic to pulmonary arterial shunt.<ref name="Corno_2009">{{Cite book| vauthors = Corno AF, Festa GP |title=Congenital heart defects : decision making for cardiac surgery. Volume 3, CT-scan and MRI |date=2009|publisher=Steinkopff|isbn=9783798517196|location=Darmstadt |oclc=433550801}}</ref>{{rp|57}} This redirected a large portion of the partially oxygenated blood leaving the heart for the body into the lungs, increasing flow through the pulmonary circuit, and relieving symptoms. The first [[Blalock–Thomas–Taussig shunt]] surgery was performed on 15-month-old [[Eileen Saxon]] on November 29, 1944 with the surgery ending in momentary success. Months later Saxon experienced more symptoms, and was operated on again, shortly before her 2nd birthday. She soon after died.<ref name="JHMI">{{cite web|url=http://www.medicalarchives.jhmi.edu/firstor.htm | title = Blalock–Taussig Shunt |work = First Operations | publisher = The Johns Hopkins Medical Institutions |archive-url=https://web.archive.org/web/20071130044447/http://www.medicalarchives.jhmi.edu/firstor.htm|archive-date=2007-11-30|url-status=live|access-date=2007-11-15}}</ref>

The Potts shunt<ref name="pmid15619282">{{cite journal | vauthors = Boshoff D, Budts W, Daenen W, Gewillig M | title = Transcatheter closure of a Potts' shunt with subsequent surgical repair of tetralogy of fallot | journal = Catheterization and Cardiovascular Interventions | volume = 64 | issue = 1 | pages = 121–123 | date = January 2005 | pmid = 15619282 | doi = 10.1002/ccd.20247 | s2cid = 46528126 }}</ref> and the Waterston–Cooley shunt<ref name="pmid15854971">{{cite journal | vauthors = Daehnert I, Wiener M, Kostelka M | title = Covered stent treatment of right pulmonary artery stenosis and Waterston shunt | journal = The Annals of Thoracic Surgery | volume = 79 | issue = 5 | pages = 1754–1755 | date = May 2005 | pmid = 15854971 | doi = 10.1016/j.athoracsur.2003.11.059 }}</ref><ref name="urlSystemic to Pulmonary Artery Shunting for Palliation: - eMedicine">{{cite web|url=http://emedicine.medscape.com/article/905950-overview|title=Systemic to Pulmonary Artery Shunting for Palliation|website=eMedicine.com|access-date=2009-01-02|url-status=live|archive-url=https://web.archive.org/web/20081229101446/http://emedicine.medscape.com/article/905950-overview|archive-date=2008-12-29}}</ref> are other shunt procedures which were developed for the same purpose. These are no longer used.

Currently, palliative surgery is not normally performed on infants with TOF except for extreme cases.<ref name="Abdulla_2011" />{{rp|173}} For example, in symptomatic infants, a two-stage repair (initial systemic to arterial shunt placement followed by total surgical repair) may be done.<ref>{{Cite book|title=Critical care of children with heart disease : basic medical and surgical concepts|date=2010|publisher=Springer-Verlag| vauthors = Munoz RA |isbn=9781848822627|location=London|page=217|oclc=663096154}}</ref> Potential complications include inadequate pulmonary blood flow, pulmonary artery distortion, inadequate growth of the pulmonary arteries, and acquired pulmonary atresia.<ref name="Corno_2009" />{{rp|59}}

=== Approaches to surgical repair ===
After years of tetralogy of Fallot surgical repair expertise, the attention shifted to the emerging evidence that long-term pulmonary insufficiency is detrimental to right ventricular function and clinical prognosis.<ref name="Bové_2017">{{cite journal | vauthors = Bové T | title = Surgical repair of tetralogy of Fallot: the quest for the 'ideal' repair | journal = Translational Pediatrics | volume = 6 | issue = 1 | pages = 64–66 | date = January 2017 | pmid = 28164034 | pmc = 5253268 | doi = 10.21037/tp.2016.11.02 | doi-access = free }}</ref><ref name="van_der_Ven_2019">{{cite journal | vauthors = van der Ven JP, van den Bosch E, Bogers AJ, Helbing WA | title = Current outcomes and treatment of tetralogy of Fallot | journal = F1000Research | volume = 8 | pages = F1000 Faculty Rev–1530 | date = 2019-08-29 | pmid = 31508203 | pmc = 6719677 | doi = 10.12688/f1000research.17174.1 | doi-access = free }}</ref> As a result, the hunt for surgical procedures to relieve right ventricular outflow tract obstruction while minimizing pulmonary regurgitation has intensified.<ref name="Bové_2017" /><ref name="van_der_Ven_2019" />

A constrained right ventricular outflow tract reconstruction with a Dacron patch matched to a nominal pulmonary annulus expansion or an annulus-sparing approach yielded primary complete repair outcomes in 94 TOF infants.<ref name="Bové_2017" /><ref name="van_der_Ven_2019" /> The pulmonary annulus size was larger in babies treated with the latter technique, as predicted.<ref name="Bové_2017" /><ref name="van_der_Ven_2019" /> After an average follow-up of around eight years, the first group had a higher than moderate PR, yet there was no significant difference in independence from severe PR after ten years.<ref name="Bové_2017" /><ref name="van_der_Ven_2019" />

Furthermore, there was no significant difference in right ventricular dilation between the two techniques.<ref name="Bové_2017" /><ref name="van_der_Ven_2019" /> Finally, they found that reconstructing the pulmonary annulus in TOF with only a tiny transannular incision and a stiff Dacron patch to inhibit pulmonary annulus extension throughout the normal growing phase produces the same long-term benefits as preserving the full pulmonary annulus integrity.<ref name="Bové_2017" /><ref name="van_der_Ven_2019" />