Shunt Detection and Quantification

1. Shunt Detection and Quantification Grossman’s cardiac catheterization, angiography, and intervention Presenter : 蔣俊彥 Supervisor : 趙庭興 醫師

2. Outline • Oximetry Run • Flow Ratio • Early Recirculation of An indicator • Angiography

3. Shunt suspection • Unexplained arterial desaturation • Unexpectedly high Oxygen content in pulmonary artery • Consider an intracardiac shunt

4. Oximetry Run • Obtain a 2-ml sample from each of the following locations: 1. Left and or right pulmonary artery 2. Main pulmonary artery 3. Right Ventricle , outflow tract 4. Right ventricle , mid 5. Right ventricle , tricuspid valve or apex 6. Right atrium , low or near tricuspid valve 7. Right atrium , mild 8. Right atrium , high 9. Superior vena cava , low (near junction with right atrium) 10. Superior vena cava , high (near junction with innominate vein) 11. Inferior vena cava , high (just at or below diaphragm) 12. Inferior vena cava , low L4-L5) 13. Left Ventricle 14. Aorta(distal to insertion of ductus )

6. Oximetry Run • A significant step-up is defined as an increase in blood oxygen content or saturation that exceeds the normal variability that might be observed if multiple samples were drawn from that cardiac chamber. • Dexter Criteria in oximtery run : a. Highest oxygen content in blood samples drawn from the right atrium exceeds the highest content in the venae cavae by 2vol %

7. b. a significant step-up at the ventricular level is present if the highest right ventricular sample is 1 vol % higher than the highest right atrial sample. c. a significant step-up at the level of the pulmonary artery oxygen content is more than 0.5% vol% greater than the highest right ventricular sample. 1 vol% = 1ml O2/100ml blood or 10mlO2/l

9. Example of Left-to-Right Shunt Detection:Atrial Septal Defect • Vena Cava SPO2= (3x67.5+1x73)/4=69% • Right Atrium SPO2= (74+84+79)/3=79% • A significant step-up 79%-69%=10% >=7% 84%-68%=16%>=11% •  SPO2 from SVC to PA is 12%-13% >8%

10. PV O2 content =0.96(14g Hgb /100ml blood) x (1.36 mlO2/g Hgb) =18.3 mlO2/100ml blood =183 mlO2/liter • PA O2 content =0.80(14)1.36x10 =152ml O2/liter • Qp = O2 consumption (ml/min)/ PVO2 content – PAO2 content = 240ml O2/min /(183-152) mlO2/L = 7.74 L/min Qs = 240ml O2/min/ Systemic arterial O2 content – Mixed venous O2 content = 240/(0.96-0.69)14(1.36)10=4.6 L/min • Qp/Qs=7.74/4.6=1.68 Left-to-right Shunt=7.7-4.7=3L/min

11. Ventricular Septal Defect • Qp = 260/(0.97-0.885)15(1.36)10 = 15 L/min • Qs= 260/(0.97-0.66)15(1.36)10 = 4.1 L/min • Qp/Qs=15/4.1=3.7 LShunt=15-4.1=10.9 L/min

12. Flow Ratio(Qp/Qs) • The ratio Qp/Qs gives important physiologic information about the magnitude of a left-to-right shunt • A Qp/Qs<1.5 signifies a small left-to-right shunt and is often felt to argue against operative correction ,particularly if the patient has an uncomplicated atrial or ventricular septal defect • A Qp/Qs between 1.5 and 2.0 are obviously intermediate in magnitude ; surgical intervention is generally recommended if operation risk is low • A Qp/Qs <1.0 indicates a net right-to-left shunt and is often a sign of the presence of irreversible pulmonary vascular disease. • A simplified formula Qp (SAO2-MVO2) Qs (PVO2-PAO2)

13. Calculation of Bidirectional Shunts • Qeff = O2 Consumption (ml/min) PV O2 content -- MVO2 content (ml/L) (ml/L) • L R = Qp(MVO2 content-PA O2 content ) (MVO2 content-PV O2 content) • R  L =Qp(PV O2 content-SAO2 content)(PAO2 content-PVO2 content (SAO2 content –MV O2 content)x(MVO2 content-PVO2 content)

14. Limitations Of Oximetry Method

16. Early Recirculation of An Indicator • Standard indicator dilution curves , performed by injection of indocyanine green into the pulmonary artery with sampling in a systemic artery, are rarely done today. • The technique can detect left-to-right shunts too small to detected by the oxygen step-up method.

17. Angiography • Selective angiography is effective in visualizing and localizing the site of left-to-right shunts and useful in localizing the anatomic size of the shunt . • Complicated lesions(e.g., endocardial cushion defects, coronary artery/right heart fistula , ruptured aneurysms at the sinus of valsalva) commonly require angiographic delineation before surgical intervention can be undertaken and helps to assess the “routine” more completely. • However, Angiography , cannot replace the important physiologic measurements that allow quantitation of flow and vascular resistance

18. Detection of Right-to-Left Intracardiac Shunts • Injection of a dilute solution of saccharin • Angiography • Oximetry • Echocardiographic methods –“bubble study ”

20. Chapter 34: Profiles in Congenital Heart Disease

22. Outline • Atrial septal Defect • Ventricular Septal defect • Patent Ductus arteriosus • Valvar aortic stenosis • Valvar Pulmonary stenosis • Coarctation of aorta • Tetralogy of Fallot • DTGA • Single Ventricle • Postop Fontan

23. Atrial Septal Defects • Surgery can be done without catheterization • Improving success with umbrella devices for transcatheter closure of central located defects of small or moderate size of ASD • Anatomic Types three main types: ostium secundum (68%) , stium primum (18%) , sinus venosus defects (6%). Secundum defects are located in the fossa ovalis below the limbs band and usually single and central and often amenable for device closure. Sinus venosus defects occur in the posterior part of the interatrial septum , near the superior vena cava , or rarely , the inferior vena cava and are not amenable to device closure , largely because of the proximity of nearby right pulmonary veins

24. Physiology • right ventricular hypertrophydecrease RV compliance ( pulmonary stenosis , pulmonary hypertension ) a smaller left-to-right shunt or a larger right-to-left shunt  reduce left ventricular compliance and produce a larger left-to-right shunt • Suggest closing all ASDs at the time of diagnosis • Catheterization Technique • advance from femoral vein , and pass from right atrium to left atrium • An alternate approach is to withdraw the catheter from the SVC to the RA with the tip positioned posteromedially, so that it drops beneath the limbic band into the fossa ovalis (as in a Brockenbrough transseptal puncture ) and then to the RA. • Primum defects are located more inferiorly , and sinus venous defects are located more superiorly . Diffiuclty in crossing a known ASD usually implies the presence of the latter type of defect. • Oximter Data

25. Step-up in oxygen-content of blood in the RA In children ,  10% in oxygen saturation between the high SVC and the RA indicates an abnormal increase . • ASD, LV-RA VSD( a VSD and associated tricupid regurgitation) • The absence of a measured shunt does not exclude an important ASD. • Pressure Data The absence of transatrial gradient does not make the diagnosis of an ASD ,pericardial tamponade , restrictive physiology • Angiography angiography for pressure equalization across the atria , catheter course , and a step-up at the atrial level is important to make a diagnosis Both angiography and balloon sizing of atrial defects are carried out to assess whether transcatheter closure is feasible Suspect ostium primum ASD and perform LV angiogram in a so-called hepatoclavicular view (LAO cranial 40º ) • Interventional Catheterization About 50%-60% of patitents with secundum ASDs and those lesions is less than 24 mm diameter , balloon sizing of the defect with a soft , deformable balloon and angiography precede device placement .

26. Ventricular Septal Defects • Loud murmur permit diagnosis of the patient with a VSD at an early age ; large defects produce symptoms early in life and demand early closure , and small defects tend to get smaller with advancing age. • “ fish or cut bait” in patients with VSDs by 2 years of age , or certainly by age 5. • Most single, clinically significant VSDs are reparied surgically without catheterization , particularly in infancy , there are patients with congenital , posoperative , posttraumatic or postinfarction VSD who require diagnostic or interventional cardiac catheterization or both. • Anatomic Types • Most congenital VSDs are defects in or about the membranous septum ; “ perimembranous “ type are located just underneath the aortic valve. • Atrioventricular canal –type VSDs are less common, are developmentally related to ostium primum defects , and occur in the posterior interventricuklar septum adjacent to the atrioventricular valves. EKG tend to be associated with a counterclock wise superior QRS in the ECG frontal plane and are see more commonly in patients Down syndrome .

27. Subpulmonary VSDs result from deficiency of the conal septum , occur more commonly in Asian patients, and are frequently associated with prolapse of the right coronary cusp and aortic regurgitation. In Caucasian patients, aortic regurgitation also occurs but it is more commonly associated with membranous defects and often with prolapse of noncoronary cusp alone or in conjunction with right cusp. • Muscular VSDs can occur anywhere in the interventricular septum ; most are “mid muscular ” , located just below the moderator band in the RV. • Swiss-cheese VSDs, have large openings on the LV side of septum but then are divided into myriad of channels by muscle bundles on the RV side. • Physiology Shunt direction are determined by the afterload that each ventricule faces. • Left-to-Right Shunt increase LV afterload (e.g., hypertension, coarctation) Decrease RV afterload ( pulmonary resistance occur in early infant ) • Left-to-right Shunt or a Right-to-Left Shunt Decrease LV afterload (vasodilator therapy) Increase RV afterload ( the development of pulmonary stenosis or pulmonary vascular disease)

28. A strong natural tendency for VSDs to close with advancing age. • Medical and not surgical management is generally advised initally for any restrictive VSD in any asymptomatic patient. • Catheterization Technique • Catheter passage through a VSD was avoided for the most part, because it was unnecessary in making the diagnosis or estimating the size of shunt. • Increase successfully efforts to close certain VSDs using a transcatheter umbrella approach. • For perimembranous defects near the tricuspid valve, the catheter is advanced into the RV and turned posteriorly (clockwise) to cross VSD into the LV outflow tract. Midmuscular and apical VSDs, most easily crossed with balloon floating catheterization from LV. Anterior muscular VSDs are best crossed from RV to LV with precurved stiff catheters and soft torque –control wires. • A “reactive” pulmonary vascular bed • Pressure Data Small VSDs have a large pressure gradient acrosss the interventricular septum. A large VSD is not to be a large defect. Small defects with associated pulmonary hypertension may mimic the pressure findings in a large defect.

29. Angiography • the membranous , conoventricular , middle and apical portions of interventricular septum are best seen in LAO veiw. • anterior portion of the septum is best seen with AP veiw. • Posterior portion of the septum (the location of atrioventricular canal defects and posterior muscular defects) is best seen with a four-chamber view. • Injection of contrast material into the high-pressure chamber (LV) is required and inject nonionic contrast volumes(1to 1.5 ml/kg) at rapid rates( <1 second) to outline the defects • Interventional Cardiology • Apical and anterior muscular defects and for most residual postoperative defects is treated by transcatheter closure • Considering that the aortic and tricuspid valves are close to the edges of most perimembranous VSDs, surgery remains the mainstay of management for these patients.

33. Patent Ductus Arteriosus • PDA is usually diagnosed in children and correct at the time of diagnosis. PDA is maintained before birth by the production of PGE. Premature babies may have an incidence of PDA as high as 40%. These are readily closed by administration of the cyclooxygenase inhibitor indomethacin. • The diagnosis of a PDA is made on the basis of physical examination and echocardiography. PDA is closed surgically and catheterization is reserved for those patients with unusal findings or suspected pulmonary hypertension. Alternatively, the PDA can be closed surgically by the video-assisted thoroscopy (VATS) technique. • PDAs are almost always located off the underside of the aortic arch just distal to the origin of the left subclavicle artery, left of the trachea, and proximal to the left main stem bronchus. • Physiology • rarely large except in patients with Down syndrome and live at high altitude. • ‘Restrictive’ PDA is characterized by a measurable step-up in PA blood oxygen saturation , perhaps some pulmonary hypertension , and no change in aortic or RV blood oxygen saturation.

34. Catheterization Technique • The techniques of a standard right-side heart catheter study estimate the hemodynamic effects of a PDA. • Transcatheter closure is accomplished eitheter from a venous approach for double-umbrella or coil occlusion or from a retrograde arterial routine fro coil occlusion. • Oximetry Data • Calculation of the shunt in a patient with a PDA is technique difficult. • Left PA blood usually has a higher oxygen saturation than that from the right PA ; and a “mixed ” PA value cannot be defined accurately. • If it is necessary to determinate whether closing of the PDA will result in a fall in PA pressure, one must temporarily balloon-occlude the duct and remeasure saturations and pressures. • Pressure Data Most PDAs do not alter right- or left-side heart pressure unless they are large. In the face of any left-side heart abnormalities (e.g., poor LV function, aortic stenosis ) , a PDA increases LV systolic pressure , LV diastolic pressure or both .

35. Angiography PDA is best done in a straight lateral view with contrast material injected distal to the PDA. • Interventional Catheterization Most workers use coils in small PDAs and a modification of the double-umbrella technique of Rashkind or a Grifka coil and bag in larger ones.

37. Aortic Stenosis • Aortic stenosis, the great majority of which occurs at vavular level, remains a common from of congenital heart disease in both children and adults. • The advent of Doppler echocardiography has markedly improved the noninvasive assessment of obstruction severity. • Catheterization indication undertake for balloon vavotomy , which cardiac dysfunction appears in the neonate or the peak-to-peak transvalvar gradient is higher than 50 mmhg , or associated with mild aortic regurgitation in older children, • Anatomic Types • More than 75% of children with valvar aortic stenosis have a bicommissural valve with leaflet fusion. The absence of the intercoronary commissure is most common. Progression of obstruction occurs in one third of those with valvar aortic stenosis, making careful follow-up mandatory. • In a smlal proportion, the obstruction is subvalvar owing to either a thin fibrous ridge or fibromuscular dysplasia of the LV outflow tract.

38. Surgery is generally indicated for significant stenosis or symptoms in order to protect the aortic valve. It is probably best delayed until after the first decade of life to reduce the risk of recurrence. • An hourglass deformity above the aortic valve , so-called supravalvar aortic stenosis. Caused at least partly by thickening of the supracoronary ridge , supravalvar aortic stenosis is often seen in association with Williams syndrome and with branch PA stenosis. • Physiology The clinical findings in all three lesions are similar in these patients with uncompromized LV function. • Catheterization Technique • Congenitally narrowed valves tend to have an opening in the posterior part of the valve, between the left and noncoronary cusps. • Because crossing congenitally stenotic aortic valves can be difficult, sometimes use a side-arm arterial sheath . Beyond infancy, usually place a second arterial catheter in ascending aorta via contralateral femoral artery. • Oximetry Data No oxygen saturation changes in the left or right heart blood • Pressure Data Multiple pigtail catheters are used to enter the LV ; a pullback tracing with these catheters may not localize the presence of subvalvar or supravalvar stenosis, making use of an end-hole catheter necessaryfor the purpose.

39. Angiography • Aortography and left ventriculography should be obtained in patients with aortic stenosis. • Aortography usually in anterioposterior and lateral views assesses the degree of aortic regurgitation as well as anatomy and mobility of the leaflets and coronary artery grossly. • Ventriculography (LAO cranial view) is used to measure the annulus diameter to estimate ventricular function, to identify subvalvar pathology and to further outline valvar and supravalvar anatomy. • Multiple views may be required to best outline the subvalvar region, including a right anterior oblique view with caudal angulation. Interventional Catheterization Balloon valvotomy has become the treatment of choice for valvar aortic stenosis at Boston Children Hospital. The results are roughly equivalent to those of surgical valvotomy.

40. Pulmonary Stenosis • Obstruction to the RV outflow tract usually are seen in association with other congenital lesions, such as TOF, transposition of the great arteries , or single ventricle. Isolated valvar pulmonary stenosis is common beyond the neonatal period. • Noninvasive diagnosis and severity assessment are now accurate in almost all circumstances and catheterization is reserved for those who require balloon valvotomy , at any age. • Anatomic types • Valvar obstruction accounts for more than 80% of isolated pulmonic stenosis. • In typical valvar pulmonary stenosisthe annulus is of normal size, the leaflets are thin , the commissures are fused and there is marked poststenotic dilation. • Dysplastic pulmonary valves exhibit a different pathology; the annulus is small , the leaflets are markedly thickened, they do not move during systole and they are fused. The main PA is short and narrow. • RV muscles bundles occur as anomalously thickened bundles of muscle within the RV cavity and are usually associated with VSD or subvalvar aortic stenosis. • The rarest form of pulmonary stenosis is branch PA stenosis. It is often associated with both supravalvar aortic stenosis and Williams syndrome.

41. Physiology • Severe forms of stenosis in the neonate generally lead to markedly reduced RV compliance with increasing RA pressure and then right-to-left shunting across a PFO. • Critical valvar pulmonary stenosis commonly manifests with cyanosis and sometimes with heart failure. Moderate degree of stenosis (e.g., gradients of 40 to 80 mmhg) rarely cause symptoms • Patients with moderate pulmonary stenosis have decreased exercise performance at cardiac catheterization. Balloon valvotomy is both safe and successful , most cadiologist now recommend dilation in any patient with more than mild stenosis before 5 years of age. • Catheterization Technique The foramen ovale is usually open , allowing catheter access to the left side of the heart from a femoral venous approach. Arterial catheters usually are required only in ill neonetes and those with severe or more obstruction. The opening in the pulmonary valve of an infant with severe pulmonary stenosis may be extremely small (less than 1 to 2 mm in diameter) Do not routinely measure PA pressure directly in infants with critical valvar pulmonary stenosis, rather perform 4 F catheters and a 0.018 inch torque wire to cross the valve , followed by rapid balloon dilation.

42. Oximetry Data • Most patient have neither a right-to-left nor a left-to-right shunt . In critical severe valvar pulmonary stenosis, a right-to-left shunt occurs at the atrial level, produceing cyanosis. • In patients with both mild pulmonary stenosis and an ASD , with a large left-to-right shunt at the atrial level, the gradient across the pulmonary valve is falsely elevated. Closing the ASD reduces the RV pressure as well as the gradient across the pulmonic valve. • Pressure Data In mild pulmonary stenosis, the RV pressure is normal. As the degree of stenosis increases, the RA a wave increases. With severe pulmonary stenosis , RV systolic pressure approaches or exceeds LV pressure, main PA pressure falls, and the PA pulse pressure dampens. Marked hypertrophy of the RV may cause the infundibular os to close during late systole , resulting in further obstruction. • Angiography Right ventriculography in straight lateral view to outline pulmonary valve and subvalvar region. A straight AP view with crainal angulation may outline the pulmonary valve, poststenotic dilation of the main PA often obscures the PA branch origin.

45. Coarctation of the aorta • Catheterization of the patient with isolated coarctation for diagnostic purposes is rarely required before surgery. Improved noninvasive imaging , including MRI allows precise anatomic definition of the lesion. • The continued incidence of recurrent coarctation after surgical repair , the common association of coarctation with other forms of congenital heart disease , and increasing use of balloon dilation in discrete nonoperated coarctation • Anatomic types all forms of coarctation occur at or just distal to the left subclavian artery, at or near the level of the old ductus arteriosus Coarctations have discrete “ curtains ” of tissue indepting the posterior wall of the aorta associated with hypoplasia of the transverse aortic arch. • Physiology The gradient across a coarctation is influenced not only by the degree of obstruction but also the degree of collateral flow around the obstruction

46. Upper-extremity hypertension, the primary sequale of a coarctation , usually resolves after surgical correction. In some children, hypertension persists despite adequate anatomic repair. The persist hypertension is more common when repair occur s late in childhood. • The general recommendation that coarctation should be diagnosed and corrected before the child reaches 3 years of age. • Oximetry Data no abnormalities in their intracardiac oxygen saturation • Pressure Data The gradient measured by pullback in the catheterization laboatory is frequently smaller than the gradient measured by sphygmomanometer in clinic. • Angiography a straight lateral aortogram usually provides excellent visualization of the coarctation. • Interventional Catheterization • Although balloon dilation frequently reduces the gradient across an unoperated coarctation site, the results particuly in babies are not generally as good as those seen surgical management. • However,balloon dilation of recurrent coarctation has provided clinically invaluable with or without stent placement.

47. Tetralogy of Fallot • The association of a malalignment VSD, infundibular and valvar pulmonary stenosis with resultant aortic overriding , and cyanosis is referred to as TOF complex. • It remains a difficult and important surgical challenge. Catheterization of infants with the lesion, especially if they are cyanotic , may be hazardous. Therefore, if echocardiography information is adequate in this age group, surgery is undertaken without catheterization. • Anatomic Types (a) branch PA stenosis (5% to 10%) (b) pulmonary atresia with PDA-dependent pulmpnary blood flow (5% to 10%) (c) additional muscular VSDs (5% to 10%) (d) aortopulmonary collateral arteries supplying blood flow to the lungs (5% to 10%) (e) coronary arterial anomalies , especially the left anterior descending arising from the right coronary artery (1% to 2%)

48. Physiology • The combination of pulmonary obstruction and a VSD produces a right-to-left shunt at the ventricular defect.The size of this shunt is unrelated to the size of the VSD, which in TOF is almost always large and unrestrictive. The right-to-left shunt and degree of cyanosis are determined primarily by the degree of pulmonary obstruction and less by the level of systemic vascular resistance. • “tetrad spells” characterized by hyperventilation , acidosis, extreme desaturation , and unconsciousness. Hypercyanotic episodes may be provoked by increased pulmonary obstruction or decreased systemic resistance. They are best treated by sedation, intravenous volume infusions , and increasing the systemic vascular resistance. • Previously , aortopulmonary shunts such as the Blalock-Tassig shunt were created surgically to increase pulmonary blood flow . Currently , so- called complete cardiac correction , relieving the pulmonary stenosis, and closing the VSD, is usually undertaken in infancy , or early childhood. • Catheterization Technique • enter the left side of the heart from the RA without difficulty. • pass the catheter from the RV both to the aorta and into the PA • Catheter passage into PA often provoke a hypercyanotic spell and catheter from the RV to aorta often produces transient heart block.

49. Oximetry Data • No abnormalities in oxygen saturation at the atrial level or ventricular level. The right-to-left shunt is documented only in the aorta. • If the cyanosis is severe , a right-to-left shunt may be present at the atrial level as well, across a PFO. The atrial shunts are signs of substanially decreased RV compliance and suggest long- standing RV hypertension. • Pressure Data RV and LV pressures are equal in patients with TOF. PA pressures are decreased in cyanotic patients without surgery. In the presence of surgically created Waterston or Potts aortopulmonary shunts , the PA is often distorted and pressures are elevated but rarely after Blalock-Taussig shunts. • Angiography • Angiographic definition of anatomic detail is the key element in the cardiac catheterization of patients with TOF. • A biplane RV angiogram with cranial angulation of the anteroposterior establishes the diagnosis , defines the anatomy of the pulmonary valve and subpulmonary region , and identifies the main PA and proximal PA branches.

50. An ascending aortogram may be necessary to further delineate coronary artery anatomy, and in particular to identify the origin of the left anterior anterior descending artery. • Aortography especially of the descending aorta is also often necessary to see whether any aortopulmonary collaterals are present. • Interventional Catheterization • Interventional procedures are rarely required before definitive surgical correction in patients with uncomplicated TOF. • However, in infants with TOF, pulmonary atresia, and diminutive Pas, dilation of hypoplastic Pas and coil embolization of aortopulmonary arteries make up an essential component of management.