24 Interventional Catheterization



10.1055/b-0035-121519

24 Interventional Catheterization



24.1 Basics


Today, an increasing number of cardiac catheterization procedures are no longer used for diagnostic purposes only. This means that more and more catheter-based treatment is now performed with interventional catheterization. In many centers today, more interventional catheterizations are performed than cardiac surgeries and catheter interventions constitute 60 to 80% of all cardiac catheterizations. The number of diagnostic catheterization procedures is steadily decreasing as echocardiography and magnetic resonance imaging of the heart gradually replace diagnostic cardiac catheterization. Many simple cardiac defects such as coarctation of the aorta, ASD, PDA, and some VSDs, can now be treated very well by interventional measures. The same is true for almost all valvular stenoses that were previously the domain of surgery. In addition, the development of materials and devices used is continually advancing, so that new areas are becoming accessible for the interventional cardiologist (e.g., percutaneous valve implantation, AV valve reconstruction, pulmonary artery banding, Fontan completion, treatment of subaortic or subpulmonary stenosis).


In the following sections some standard routines will be presented as examples of how patients can be treated using interventional procedures.



24.1.1 Preparation


Careful preparation is essential before a planned intervention, just as it is before surgery. This process usually includes the following preparations and examinations:




  • Organization of the existing documents, especially outpatient records, old medical reports, operation reports, cardiac catheterization reports, previous imaging (MRI, CT), and other details prior to the investigation



  • Discussion and clarification of the indication



  • General admission examination, especially




    • Neurological status



    • Ruling out infection



    • Ruling out clotting disease (petechiae, bruising, medical history)



    • Pulse or vascular status



  • Pulse oximetry



  • Blood pressure in all four limbs



  • Recent ECG—that is, obtained within the last 2 (to 3) months



  • Recent echocardiography



  • Insertion of a peripheral intravenous access port (routine blood sampling is usually not necessary)


Patient information


The patient should always be informed by an experienced colleague from the cardiac catheterization team who knows the nature of the intended catheter investigation and intervention and can explain it accordingly. Ideally, the procedure should be discussed with the patient and his or her parents before the cardiac catheterization. The general and specific risks associated with the planned cardiac catheterization and intervention should always be explained. The risks should also be documented in the patient information sheet. Examples of general risks are:




  • Sedation → Overreactions → Intubation → Intensive care monitoring



  • Puncture → Bleeding → Transfusion



  • Puncture → Thrombosis → Perfusion disturbance → Lysis treatment



  • Puncture → Thrombosis → Embolism



  • Puncture → Vascular lesion, vascular occlusion → Operation



  • Infection → Antibiotic treatment



  • Rhythm disorder → Pharmacological treatment, pacemaker treatment



  • Air embolism, systemic thromboembolism



  • Contrast medium intolerance → Shock→ Intensive care



  • Perforation → Pericardial effusion → Tamponade → Puncture/surgery



  • Radiation exposure


The specific complications of the individual cardiac defects and interventions and alternative treatment options are discussed in the respective chapters of this book.


In addition, the cardiac defect and the planned intervention should be illustrated in a diagram in the information sheet, and the questions of the parents and the patient should be discussed in detail. It should be emphasized that the overall risk for a simple diagnostic cardiac catheterization is 5% and the risk is somewhat higher for an interventional procedure. For complex interventions, the risk is sometimes comparable to that of surgery.


Sometimes a vascular puncture in the area of the neck and upper chest is necessary. For example, access to the jugular vein or to the subclavian vein is chosen following an upper cavopulmonary anastomosis or if there is known thrombosis of the leg/pelvic vessels. In these cases, the following additional complications have to be pointed out (risk < 5%):




  • Accidental puncture of the carotid artery



  • Puncture of the trachea/larynx



  • Pneumothorax



  • Hematothorax


Blood tests


For most interventional procedures, no “routine” blood tests are necessary before the planned operation. Should a patient have clinical signs of infection, for example, cardiac catheterization may be allowed or not based on the clinical examination. Likewise for electrolytes, Hb tests, kidney or liver enzymes: during cardiac catheterization, blood tests can be performed at any time, so electrolytes, Hb levels, and blood gases can be determined if necessary, using modern equipment in the catheterization laboratory. A clinical history of coagulation disorders is an important consideration that may trigger specific additional clotting tests.


When there is an increased risk for blood loss or myocardial perforation in certain examinations or interventions, additional laboratory tests can be ordered on a case-by-case basis (blood typing and cross-matching). An example of such an intervention is the catheter interventional opening of pulmonary atresia.



24.1.2 Sedation/Anesthesia/Monitoring


In most centers, cardiac catheterization is almost always performed in deep conscious sedation. General anesthesia is not usually necessary. This also applies to studies in which transesophageal echocardiography is needed (e.g., ASD closure). However, the safety measures and standards which apply for continuous monitoring by specialized medical and nursing staff are the same as those for surgery and anesthesia.


Premedication


A premed is given before the patient is moved to the cardiac catheterization laboratory (e.g., midazolam 0.1 mg/kg IV).


Monitoring


During catheterization, the patient is monitored continuously with ECG, pulse oximetry, and frequent checks of blood pressure. If necessary, oxygen is administered.


Deep conscious sedation


For deep conscious sedation with ketamine (and atropine) and propofol, the following regimen is recommended:




  • Monitoring with pulse oximetry, ECG, blood pressure



  • Oxygen mask / resuscitation bag at hand



  • Initiate sedation with ketamine 2 mg/kg IV



  • Atropine: at least 100 μg, max. 500 μg IV



  • Propofol bolus of 1 mg/kg IV



  • Propofol infusion of 5 mg/kg/h



  • If necessary, further doses of ketamine and propofol as indicated


Monitoring after cardiac catheterization


After completion of the procedure, patients are brought directly to the recovery area or ward for further monitoring. Monitoring in an intensive care setting or unit is not necessary in most cases. A physician accompanies the patient during transport to the aftercare station. The patient is given oxygen during transport and is continuously monitored with pulse oximetry and ECG.


Transfer to the ward


The patient is then handed over to the physicians and the nursing staff on the aftercare ward. The clinical condition is documented jointly (oxygen saturation, breathing, circulation).



24.1.3 Postinterventional Measures


Every interventional catheterization should be followed by a standardized and well-defined treatment schedule consisting of pharmacological treatment, checkups, and monitoring according to the procedure performed.


Such an algorithm may be as follows:




  • Heparinization




    • Not usually needed after a venous puncture. In cyanotic patients, 200 IU/kg/d until the next morning, continuous IV administration



    • After an arterial puncture, for 24 hours or until the next morning: 400 IU/kg/d, continuous IV administration



    • After interventions, for 36 to 48 hours or until the morning of the second day: 400 IU/kg/d, continuous IV administration



  • Infusion treatment: until the patients are awake and able to drink



  • Food/drink: As soon as the patients are awake, start with clear liquids; if well tolerated, give food and drink as desired.



  • Monitoring: Carry out continuous monitoring of pulses, blood pressure, and oxygen saturation through a central monitoring system with documentation; include assessment of the leg perfusion and neurological status.



  • Post-catheterization bleeding: If there is bleeding at the puncture site, renew (compression) dressing and extend monitoring for 12 hours.



24.2 Special Interventional Catheterization Procedures



24.2.1 Interventional Catheterization for Valvular, Vascular, and Outflow Tract Stenosis



Basics of Balloon Valvuloplasty

Definition


In balloon valvuloplasty, the narrow site of a vessel or a stenotic valve is stretched when the balloon catheter is inflated so that, ideally, only little or no residual stenosis remains.


Material


Balloon catheters of different lengths and diameters are available as well as balloons with different pressure capacities (low-pressure and high-pressure balloons). In addition, there are special balloons with special shapes (e.g., Inoue balloon for mitral valve valvuloplasty) or with special features (such as cutting balloons with small blades attached).


Procedure


First the pressure gradient is determined and the anatomy of the stenosis as well as the upstream and downstream vessels is visualized. A combination of angiography and previous echocardiography or MRI findings is useful for this. Then a guidewire is advanced through the stenosis into the downstream vascular area (e.g., in pulmonary valve stenosis into the pulmonary artery) or, if retrograde probing is performed, into the upstream area (e.g., for aortic stenosis into the left ventricle). Then the deflated balloon catheter is placed in the stenotic area, oriented by cardiac catheter angiography.


When the balloon catheter has been placed correctly in the stenotic area, it is briefly inflated to the maximum pressure specified by the manufacturer. This process is documented (usually 6 frames/s). Then the balloon is deflated and the balloon catheter is withdrawn with the guidewire remaining. An angiography catheter is then placed at the site of the former stenosis, the pressure is measured and an angiography performed. If the stenosis is not sufficiently widened, the dilation procedure may be repeated with a larger or harder balloon or a cutting balloon, or a stent is implanted.


Complications


Uncontrolled tearing of the vessel wall may develop during the dilation process. There is a risk of dissection or rupture, later thrombosis, embolism or even restenosis depending on the tissue repair process. In valvular stenosis, accidental laceration or avulsion of a leaflet may cause severe regurgitation.


Treatment


The procedure is often followed by heparinization for 1 to 2 days and by giving low-dose aspirin (3–5 mg/kg orally) to avoid excessive thrombosis, embolism, or vascular occlusion.


Checkups


Depending on the treated site (valve or vessel), echocardiography checkups are usually sufficient, but sometimes an MRI is also necessary.



Valvular Aortic Stenosis

Indication


Overall, the indication criteria for balloon valvuloplasty of the aortic valve are still evolving as, on the one hand, the interventional results are promising while, on the other hand, the risk of the procedure is relatively low. Generally accepted indications are:




  • Gradient related (Doppler gradient > 50 mmHg)



  • Cardiac decompensation or decreasing left ventricular function



  • Increasing cardiac overload (left ventricular hypertrophy, poor diastolic function)



  • ST segment changes under stress



  • A still-competent aortic valve is a precondition (aortic regurgitation ≤ 2°)


Preliminary examinations


An ECG that is no more than 2 months old is recommended; if it is suspicious, a 24-hour Holter ECG or exercise ECG is also recommended. Moreover, a recent echocardiography may be useful including determination of the valve annulus diameter, anatomy of the valve (bicuspid, tricuspid), mean and maximum gradient, aortic regurgitation, left ventricular function, mitral regurgitation, isthmus, ductus, and exclusion of a Shone complex.


Risks/patient information


The overall risk is below 10%, including the risk of rupture of the valve, acute and severe aortic regurgitation, emergency surgery with possible valve replacement, myocardial ischemia, arrhythmias, AV block, development of mitral regurgitation, infection/endocarditis, perfusion disorder, or vascular occlusion at the arterial puncture site.


Procedure


In small children, an antegrade approach (across an ASD or a patent foramen ovale) may be attempted, otherwise a retrograde approach via an arterial puncture should be undertaken.


Cardiac catheterization/treatment


First, pressure measurement and ascendogram, measurement of the valve annulus, probing and angiography of the left ventricle (Fig. 24.1). Then switch the catheter to a long exchange wire, then place the balloon catheter. Balloon dilation (balloon diameter 80–110% of the valve annulus diameter). Check of pressure in the left ventricle, re-angiography of the left ventricle and again ascendogram (aortic regurgitation?). In older children, pacemaker stimulation of the right ventricle. For this, quick VVI stimulation (300–400/min) during balloon dilation can briefly reduce ejection from the left ventricle due to tachycardia so the balloon is not displaced too much by the pulsation of blood flow.


Heparinization


Administration of 100 IU/kg intravenously during cardiac catheterization, then 400 IU/kg/d as a continuous infusion until the morning of the second day.


Echocardiography after cardiac catheterization


Possible aortic regurgitation, the mean and maximum residual gradient, left ventricular function, and a possible new occurrence of mitral regurgitation should be noted.


Medication


Aspirin 3 to 5 mg/kg for 3 months, endocarditis prophylaxis for 6 months if needed.

Fig. 24.1 Dilation of a valvular aortic stenosis. a First an ascendogram is made. b Then angiography of the left ventricle and visualization of the valvular stenosis, the thickened valve, and the jet across the stenotic valve. c Dilation of the valve under high-frequency stimulation around 350/min. d Finally angiography to document possible newly developed aortic regurgitation.


Critical Aortic Stenosis of the Neonate

Indication


Owing to the typical hemodynamic situation (ductal-dependent systemic perfusion) and the fact that the left ventricular function is usually considerably impaired, there is an indication regardless of the gradient in a still-competent aortic valve (aortic regurgitation < 2°).


Preliminary examinations


Patients are usually admitted under intensive care conditions; they are very often ventilated, critically ill newborns. ECG, detailed echocardiography, chest X-ray, and preparation for surgery with cardiopulmonary bypass is necessary.


Echocardiography


Visualization of the valve annulus diameter, aortic regurgitation, valve anatomy (bicuspid, tricuspid), mean and maximum gradient, left ventricular function, mitral regurgitation, isthmus, ductus arteriosus, pulmonary artery diameter, exclusion of a Shone complex.


Preparation


Preparation should be the same as for cardiopulmonary bypass surgery as dictated by hospital standards. If necessary, this may include first inserting an arterial catheter (umbilical) and a central venous catheter, catecholamine treatment, and in every case prostaglandin treatment. If still possible, give umbilical care (keep navel moist) so that antegrade cardiac catheterization via the umbilical vein remains possible.


Risks/patient information


The risk is high because the patient is usually a critically ill neonate with impaired ventricular function. Risks include a valve rupture, acute and severe aortic regurgitation, emergency surgery, possibly with valve replacement (homograft implantation) or Ross procedure, myocardial ischemia, arrhythmias, AV block, mitral regurgitation, infection/endocarditis; for an arterial puncture, perfusion disturbance or vascular occlusion.


Procedure


Whenever possible, an antegrade approach across an ASD or a patent foramen ovale should be attempted, possibly via the umbilical vein, otherwise a retrograde approach via an arterial puncture should be undertaken.


Cardiac catheterization/treatment


Ascendogram, measurement of the valve annulus, probing and angiography of the left ventricle, switch to an exchange wire, then balloon dilation (balloon diameter max. 80–100% of the valve annulus diameter), check of left ventricular pressure, angiography of the left ventricle, ascendogram (aortic regurgitation?). In a critically ill child, the dilation is often performed based solely on echocardiography findings and without pressure measurements or angiographies.(Fig. 24.2).


Monitoring


Intensive care monitoring, catecholamines and prostaglandin reduced depending on the clinical status, regular echocardiography checkups.


Heparinization


Administration of 100 IU/kg as an intravenous bolus during cardiac catheterization, then 400 IU/kg/d in a continuous infusion until the morning of the second day.


Echocardiography after cardiac catheterization


Aortic regurgitation, mean and maximum residual gradient, left ventricular function, mitral regurgitation, mitral stenosis, PDA, isthmus, exclusion of a Shone complex.

Fig. 24.2 Antegrade dilation of critical aortic valve stenosis. a First, antegrade probe of the stenotic aortic valve with a thin guidewire. For this a guide catheter is inserted through the inferior vena cava, the right atrium, and across the septal shunt into the left atrium and left ventricle. After passing the aortic valve, the guidewire finally crosses the aortic valve into the ascending aorta. The dilation balloon is positioned in the stenotic valve. When the dilation balloon is inflated, a distinct notch forms in the balloon, which is a sign of the valvular stenosis. b After repeated dilations, the notch in the dilation balloon is no longer visible. The stenotic valve is widened.


Note

The balloon valvuloplasty of critical aortic stenosis in the neonate is carried out regardless of the gradient. The children often need an adaption phase of varying length until the left ventricle has recovered sufficiently. Long-term catecholamine support and possibly ventilation are often required.



Supravalvular Aortic Stenosis

Indication


In a supravalvular aortic stenosis, an indication for intervention is relatively rare. The results for a “classic” supravalvular aortic stenosis in Williams–Beuren syndrome are poor. Postoperative supravalvular stenosis (e.g., after Damus–Kaye–Stansel anastomosis is practically the only indication):




  • Gradient related (Doppler gradient over 50 mmHg)



  • Cardiac decompensation or decreasing ventricular function



  • Increased cardiac overload



  • ST segment changes under stress


Preliminary examinations


ECG no more than 2 months old; 24-hour Holter ECG and exercise ECG only if the most recent ECG was abnormal.


Echocardiography


The following questions should be answered: valve annulus diameter, aortic regurgitation, anatomy of the stenosis, mean and maximum gradient, left ventricular function, isthmus, other stenosis of the head and neck vessels.


Risks/patient information


The risk is less than 5%, dissection and coronary problems could lead to myocardial ischemia, arrhythmias, and AV block; perfusion disturbance or vascular occlusion for arterial punctures.


Procedure


In univentricular hearts, an antegrade approach may be possible (across an ASD or the ventricle), otherwise a retrograde approach via an arterial access is used.


Cardiac catheterization/treatment


Ascendogram, measurement of the valve annulus, probe of the left and right ventricle, angiography, switch to exchange wire, balloon dilation, check of ventricular pressure, ventricular angiography, ascendogram (aortic regurgitation?).


Monitoring


Routine monitoring and a 12-lead ECG after the intervention, additional monitoring on an ECG monitor with ST-segment analysis, 24-hour Holter monitoring only if the ECG is abnormal.


Heparinization


Administration of 100 IU/kg as an intravenous bolus during cardiac catheterization, then 400 IU/kg/d as a continuous infusion until the morning of the second day, and aspirin 3 to 5 mg/kg for 3 months.


Echocardiography after cardiac catheterization


Aortic regurgitation, mean and maximum residual gradient, ventricular function, and wall dyskinesia should be documented.


Medication


Aspirin 3 to 5 mg/kg for 3 months, endocarditis prophylaxis for 6 months.



Mitral Stenosis

Indication


Overall, balloon valvuloplasty of the mitral valve is only rarely indicated in children in Europe. From a global perspective, it is a common procedure after rheumatic fever or—rarely—because of endocarditis. The results are satisfactory for stenosis of previously normal valves. In primarily anomalous valves (e.g., parachute or hammock valve), or especially after surgical reconstruction, the results are unsatisfactory. Indications are:




  • Gradient dependency (Doppler gradient of 10 mmHg)



  • Signs of “left decompensation” (pulmonary edema, pulmonary congestion)



  • Atrial arrhythmias



  • Ectatic left atrium with thrombi



  • Intermittent pulmonary edema—congestive cough



  • Significant pulmonary hypertension



  • Progressive deterioration of physical capacity


Preliminary examinations


ECG no more than 2 months old, 24-hour Holter ECG and exercise ECG only if the most recent ECG was abnormal, cardiopulmonary exercise test for larger patients.


Echocardiography


Valve annulus diameter, anatomy, mean and maximum gradient, left ventricular function, mitral regurgitation, ASD or patent foramen ovale, and pulmonary hypertension should be investigated.


Risks/patient information


Risk less than 5%, rupture of the valve, acute severe mitral regurgitation (often not well tolerated), emergency operation (low risk), valve replacement, dissection, tamponade, death, myocardial ischemia, arrhythmias, AV block, infection/endocarditis.


Procedure


Antegrade approach through the femoral veins.


Cardiac catheterization/treatment


Transseptal probing of the left atrium , if necessary by transseptal puncture; rarely, left atrial angiography and pressure measurement, probe of the left ventricle with wire, insertion of the balloon catheter (e.g., Inoue balloon) and dilation, check of left atrial and left ventricular pressure, angiography of the left ventricle (mitral regurgitation?).


Echocardiography after cardiac catheterization


Mitral regurgitation, mean and maximum residual gradient, left ventricular function, pulmonary hypertension.


Medication


Aspirin 3 to 5 mg/kg for 3 months, endocarditis prophylaxis for 6 months if necessary, possibly treatment/prophylaxis of rheumatic fever.



Note

Balloon valvuloplasty of the mitral valve has become very rare in Europe, but in other countries with more frequent rheumatic fever, it is one of the most commonly performed interventional procedures. Congenital mitral valve defects are not successfully treated by interventional catheterization.



Balloon Valvuloplasty of Coarctation of the Aorta

Indication


Overall, the indication criteria for balloon valvuloplasty of coarctation of the aorta are evolving as, on one hand, the results are promising while, on the other hand, the risk of the procedure is relatively low. In neonates and children under 6 months, the recurrence rate is unsatisfactory (elastic ductal tissue), which is why this group is usually treated surgically. Clinical as well as pharmacological exercise tests (e.g., orciprenaline stress test) are often helpful in determining the indication. Accepted indications are:




  • Doppler gradient well above 20 mmHg



  • Absent or severely attenuated inguinal pulses



  • Blood pressure difference arm/leg well above 20 mmHg



  • Hypertension (exercise test, long-term blood pressure measurement)



  • Cardiac decompensation or decreasing left ventricular function



  • Increasing cardiac overload (left ventricular wall thickness)



  • ST segment changes on exertion



  • Increasing aortic regurgitation


Preliminary examinations


ECG not more than 2 months old, echocardiography; if possible, in older children, MRI with 3D reconstruction and dimensions of the aortic arch and isthmus.


Echocardiography


Visualization of the diameter of the arch, the coarctation, the descending aorta at the diaphragm level, aortic valve, valve annulus diameter, aortic regurgitation, mean and maximum gradient, left ventricular function, mitral regurgitation, isthmus, ductus arteriosus, possibly gradient under stress, exclusion of a Shone complex.


Risks/patient information


The risk is well below 5%. There are a few patients beyond the neonatal age who still require surgery owing to insufficient success of catheter intervention (elastic tissue). Possible complications are dissection due to massive overdilation, aneurysm formation, hematothorax, transfusion, chest tube, emergency stent implantation, emergency surgery, death, paraplegia (extremely rare). The restenosis rate is over 20% (same as for a surgical procedure), and perfusion problems or vascular occlusion may occur after the arterial puncture. There is typically mild chest pain after the intervention.


Procedure


In young children, an antegrade approach (across ASD or patent foramen ovale) may be possible. In most patients, however, a retrograde approach via an arterial puncture is undertaken access is used.(Fig. 24.3).


Cardiac catheterization/treatment


Ascendogram, measurement of each arc segment and determining the anatomy, pull-back pressure, possibly orciprenaline stress test (Alupent), switch to an exchange wire, balloon dilation, control angiography, pull-back pressure, possibly another pharmacological stress test.


Monitoring after dilatation


Additional monitoring and documentation of blood pressure at least every 30 minutes through the night and for 24 hours if any questions remain, blood pressure, apply generous analgesia and, systematic antihypertensive therapy (e.g., carvedilol, ACE inhibitors).


Heparinization


Administration of 100 IU/kg as an intravenous bolus during cardiac catheterization, then 400 IU/kg/d in a continuous infusion until the morning of the second day.


Checkups after cardiac catheterization


Echocardiography: documentation of mean and maximum residual gradient, left ventricular function, perfusion of the inguinal vessels.


MRI: Routinely after 6 months to document the result as well as to rule out aneurysms.


Medication


See Aortic Stenosis.

Fig. 24.3 Balloon dilation of coarctation of the aorta. a First the balloon is advanced up to the stenosis. b The stenosis is widened by inflating the balloon. c After dilation, the balloon is deflated and the catheter is retrieved.


Dilation of Coarctation of the Aorta of the Neonate

Indication


There are currently very few generally accepted indications for the interventional treatment of the coarctation of the aorta of the neonate. Children are not usually treated by interventional catheterization before the age of 6 months because the risk of recurrence is very high (over 70%). The procedure is indicated for sick newborns with additional problems that impede rapid surgery (e.g., necrotic enterocolitis, unclear syndromes, brain hemorrhage) or in critically ill children with cardiac decompensation, as well as children with cardiomyopathy and mild coarctation of the aorta.


Preliminary examinations


Cranial ultrasound (to rule out brain hemorrhage), other organ diagnostic workups under intensive care conditions (the neonate is usually ventilated and critically ill). ECG, echocardiography, chest X-ray, surgical preparation, prostaglandin treatment, possibly catecholamines.


Echocardiography


The diameter of the aortic arch, coarctation of the aorta, descending aorta at diaphragm level, aortic valve, valve annulus diameter, aortic regurgitation, valvular anatomy, mean and maximum gradient, left ventricular function, mitral regurgitation, isthmus, ductus arteriosus should be documented; a Shone complex should be ruled out.


Preparation


Same as for cardiopulmonary bypass surgery; if necessary, insertion of an arterial catheter (umbilical) as well as a central venous catheter, catecholamine treatment, prostaglandin treatment obligatory in all patients.


Risks/patient information


The risk is high as the neonate is critically ill. There is a very high recurrence rate due to elastic ductal issue. Dissection in massive overdilation, hematothorax, transfusion, chest drainage, emergency stent implantation, emergency surgery, death, and perfusion disturbance or vessel occlusion and rupture after arterial puncture may occur. Surgery is usually required soon afterward as the intervention is only a palliative measure.


Procedure


An antegrade approach may be possible (across an ASD or patent foramen ovale), but in most cases a retrograde approach via an arterial access is used.


Cardiac catheterization/treatment


Ascendogram, measurement of each segment of the arch and assessment of the anatomy, change to wire, balloon dilation (Fig. 24.4). Switch to an exchange wire, control angiography, leave arterial catheter in place. Dilation may also be performed also based only on the echocardiography.


Monitoring


Use intensive care monitoring, taper catecholamines, discontinue prostaglandin, carry out regular echocardiography checkups. In addition, blood pressure is monitored every 30 minutes overnight, perfusion of the legs should be monitored with continuous pulse oximetry. Early enteral nutrition intake should be instigated on the same day, and possibly antihypertensive treatment (e.g., diuretics, ACE inhibitors, carvedilol).


Heparinization


Administration of 100 IU/kg as an intravenous bolus during cardiac catheterization, otherwise proceed according to intensive care guidelines and patient need.


Echocardiography after cardiac catheterization


Access aortic regurgitation, mean and maximum residual gradient, left ventricular function, mitral regurgitation, mitral stenosis, PDA, exclusion of a Shone complex.

Fig. 24.4 Anatomy of coarctation of the aorta in the neonate with perfusion of the lower half of the body across the patent ductus arteriosus.


Stent Implantation in Coarctation of the Aorta

Indication


The indication criteria for stent implantation as treatment of coarctation of the aorta are still evolving because the results are promising and the risk of the procedure is low—also due to the development of new materials with small sheath sizes. The issue as to whether covered stents should be used or not, is still under discussion.


In small children, stents are used only as an emergency solution intraoperatively in hypoplastic vessels. Coronary stents or small vascular stents are used as bailout options in neonates or small children. Specifically designed stents for neonates that can be redilated to adult size are under clinical development. Exercise tests are useful for determining the indication in so called “mild coarctations”. The acceptable indications for body weight of at least 20 kg are the same as for unstented coarctation of the aorta:




  • Doppler gradient well above 20 mmHg



  • Absent or severely attenuated inguinal pulses



  • Blood pressure difference arm/leg well above 20 mmHg



  • Hypertension (exercise test, long-term blood pressure measurement)



  • Cardiac decompensation or decreasing left ventricular function



  • Increasing cardiac overload (left ventricular wall thickness)



  • ST segment changes under stress



  • Increasing aortic regurgitation


Preliminary examinations


ECG no more than 2 months old, current echocardiography with documentation of the diameter of the vessels, MRI with 3D reconstruction and dimensions; possibly, exercise tests, 24-hour blood pressure monitoring.


Echocardiography


The diameter of the aortic arch and coarctation, the descending aorta at diaphragm level, aortic valve, valve annulus diameter, aortic regurgitation, valvular anatomy, mean and maximum gradient, left ventricular function, mitral regurgitation, isthmus, ductus arteriosus should be documented; a Shone complex should be ruled out.


Risks/patient information


The risk is less than 5%, possible dissection due to massive overdilation, hematothorax, transfusion, chest drainage, aneurysm formation, emergency implantation of covered stents, emergency surgery, death, paraplegia (rare), low rate of restenosis (< 5%), possibly two-stage procedure with re-dilation in 6 to 12 months, perfusion disorders or vessel occlusion for an arterial puncture. Typically there is mild chest pain after the stent implantation.


Procedure


Usually an antegrade approach via an arterial puncture is attempted.


Cardiac catheterization/treatment


Ascendogram, measurement of each arch segment and determination of the anatomy, pull-back pressure, possibly orciprenaline (Alupent) stress test, switch to an exchange wire (balloon dilation, control angiography), insertion of the long transport sheath, control angiography using hand injections, stent implantation (Fig. 24.5), pull-back pressure, possibly repeated pharmacological stress test. In larger children and arch stenosis, pacemaker stimulation (rare) may be instigated to ensure proper stent placement.


Monitoring


Heparinization, medication, and monitoring are the same as for balloon dilation.

Fig. 24.5 Stent implantation for coarctation of the aorta. a First a balloon catheter with a stent is inserted up to the stenosis. b The balloon is inflated to widen the stenosis and expand the stent. c After dilation the balloon is deflated and the catheter is retrieved. The stent maintains the dilation.

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Jun 13, 2020 | Posted by in CARDIOLOGY | Comments Off on 24 Interventional Catheterization
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