Fetal Surgery for Congenital Heart Disease Periprocedural Care

Updated: Nov 05, 2019
  • Author: Anita J Moon-Grady, MD, FACC, FAAP, FASE; Chief Editor: Hanmin Lee, MD  more...
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Periprocedural Care

Patient Education and Consent

For any fetal intervention, the mother is an integral part of the management strategy. There is an expected commitment from the mother, as well as the family, for both emotional and logistic support.

Accordingly, considerable time and expertise are devoted to detailed patient counseling aimed at providing patients and their families with all the information needed to make an informed decision before patient selection. Opportunities are given for a two-way discussion at every step. Counseling is both multidisciplinary and multistaged, involving members of the above-mentioned team, as appropriate.

The patients are carefully counseled regarding risk of fetal loss, preterm delivery, preterm premature rupture of membranes (PPROM) and its management, maternal or fetal infection, and maternal hemorrhage. Patients are further counseled, when appropriate, regarding the risk of fetal neurologic injury and the risks associated with prematurity, including higher surgical morbidity and mortality in comparison with an infant born at term with the same lesion.

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Preprocedural Echocardiographic Evaluation

Five preoperative echocardiographic criteria have been suggested for performance of balloon valvuloplasty in midtrimester fetuses (18-32 weeks’ gestation) with severe aortic stenosis, associated with a high likelihood of postnatal biventricular repair. [33]  A refinement of these criteria that may further stratify the likelihood of success was published in 2017 [26] ; however, the criteria below remain reasonable.  All five of the criteria must be met.

1. The dominant cardiac anatomic anomaly is valvular aortic stenosis with all of the following:

  • Decreased mobility of valve leaflets
  • Antegrade Doppler color flow jet across aortic valve smaller than the valve annulus diameter
  • No or minimal subvalvar left ventricular outflow obstruction

2. Left ventricular function is qualitatively depressed.

3. Either retrograde or bidirectional flow is present in the transverse aortic arch or two of the following are present:

  • Monophasic mitral inflow Doppler pattern
  • Left-to-right flow across atrial septum or intact atrial septum
  • Bidirectional flow in pulmonary veins

4. The left ventricular long-axis Z-score is greater than –2.

5. The threshold score is greater than 4, fulfilling more than four of the following:

  • Left ventricular long-axis Z-score greater than 0 (1 point)
  • Left ventricular short-axis Z-score greater than 0 (1 point)
  • Aortic annulus Z-score greater than –3.5 (1 point)
  • Mitral valve annulus Z-score greater than –2 (1 point)
  • Mitral regurgitation or aortic outflow peak systolic gradient greater than 20 mm Hg (1 point)
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Preprocedural Planning

Once the mother and fetus are considered eligible for the procedure, the various possible anesthetic scenarios (depending on the details of the intervention) are fully discussed with the mother, and additional relevant written informational material is provided as appropriate.

Fetal positioning and uterine access are important criteria in the final decision making about the type of anesthesia, and the improbability of making a concrete plan at the initial juncture should be emphasized. In some cases, the procedure may be performed in a minimally invasive manner, necessitating only local anesthesia, whereas in others, more manipulation may necessitate regional or even general anesthesia. [16]

Before offering the procedure, the participating fetal treatment members—including perinatologists, high-risk nurse/midwives, obstetricians, pediatric cardiologists, pediatric cardiac interventionist, maternal and fetal anesthesiologists, and relevant procedure/operating room personnel trained in maternofetal surgical requirements—meet again as a group to discuss the technical issues involving the proposed procedure, the likely means of access, the equipment required, and any other medical concerns about the patient.

If the fetal gestational age is determined to be in a viable range (an assessment that may be subjective and that varies depending on the cardiac lesion), a discussion regarding extent of resuscitative efforts, including the possibility of urgent operative delivery, must be undertaken before the day of the procedure. If delivery is to be offered, the option of preprocedural steroid therapy for promotion of fetal lung maturity should be discussed.

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Equipment

Routine surgical instruments that are required for percutaneous uterine access, as well as via laparotomy or a laparoscopic entry, are used.

Instruments particular to fetal cardiac intervention include an access cannula (usually a wide-bore 18- or 19-gauge blunt needle with a sharp stylet) with a guide wire appropriate for intracardiac manipulation (ie, one having a pliable tip with a stiffer shaft).

Angioplasty balloons, stents, or both should be available, in an appropriate range of sizes.

Angioplasty balloon catheters can be preloaded on a 0.014-in. wire for valvuloplasty.

Occasionally, an additional sharp-tipped (Chiba) needle is required to enter the heart and to perforate the atretic valve or the atrial septum.

Apart from a 18-gauge curved-tip cannula that is specifically designed for this purpose (SHARC Access Needle Set; ATC Technologies, Wilmington, MA), most other instruments used for fetal cardiac surgery are simple improvisations from the cardiac catheterization set and designed for percutaneous coronary artery intervention.

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Patient Preparation

Anesthesia

Maternal general anesthesia may be considered when a laparotomy is planned. Regional spinal anesthetic is almost always preferred, when possible, with additional intravenous sedation as needed for maternal comfort. The choices of anesthesia are usually made on an individual basis and depend on the medical and obstetric factors present and on the institution's and team's experience and preference.

Positioning

Once maternal anesthesia is achieved, the patient is usually placed in a slight left lateral orientation so as to prevent obstruction of venous return by the gravid uterus.

An ultrasound-guided technique is adopted using high-quality portable equipment. Initially, the obstetric sonographer (along with the fetal cardiologist in many institutions) reassesses the fetal lie to plan the optimal access site.

The optimal fetal position for ventricular aortic valve procedures is with the fetal spine to maternal right for a vertex orientation and with the fetal spine to maternal left for a breech orientation (a transverse lie is not optimal) with the left thorax accessible.

For right ventricular entry, fetal chest up/spine down positioning, granting easy needle access to the anterior fetal chest, is best. For transthoracic atrial septal procedures, positioning may be such that access to the atrial septum via the left posterior thorax (through the left atrium) or the right thorax (through the right atrium) can be gained. The choice of entry into the maternal abdomen is then based on the uterine access site most conducive to aligning the needle to the fetal heart.

The percutaneous ultrasound-guided approach is usually preferred because of its obvious noninvasive benefits. However, in some cases, a small laparotomy may not be avoidable if ideal fetal position and transuterine access to the fetus are to be achieved. In these cases, though the maternal abdomen is opened, a hysterotomy is generally avoided.

Direct access through a laparotomy with port-access uterine entry carries a higher risk of preterm labor than percutaneous access does. When laparotomy is performed, a Pfannenstiel incision should suffice in most situations; however, a midline vertical incision has also been employed.

Fetal movement may make these procedures technically more difficult while increasing the risk of fetal injury and duration of the procedure. Maternal anesthesia alone does not result in adequate suppression of fetal activity; therefore, in most cases, additional fetal anesthesia is administered. The usual choice of fetal anesthetic is fentanyl in combination with pancuronium bromide injected into the fetal gluteal region under ultrasound guidance to induce safe short-term paralysis of the fetus. [67]

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Monitoring & Follow-up

Maternal vital signs are routinely monitored for the entire duration of the procedure, and ventilatory support is made available, if required. Invasive maternal blood pressure monitoring and judicious use of volume expansion in combination with pharmacologic manipulation of maternal heart rate and blood pressure should be performed under the supervision of an experienced obstetric anesthesiologist. Continuous ultrasound guidance allows fetal monitoring.

Maternal postprocedural care after invasive fetal procedures is fairly standard and usually involves overnight monitoring. Routine periprocedural tocolysis may be given. If indomethacin is used, fetal well-being should be reassessed with ultrasonography at least daily; ductal constriction due to the use of nonsteroidal anti-inflammatory drugs is poorly tolerated in fetuses undergoing cardiac intervention. [68]

Fetal echocardiography should be performed early after the procedure to evaluate the technical success of the intervention. The assessment should target valvar flow (both antegrade and regurgitant), direction of flow in the aortic arch (for aortic valvuloplasty), and flow across the atrial septum and flow pattern in the pulmonary veins (for atrial septal procedures).

Periodic reassessment throughout the remaining gestation is also performed and may demonstrate improvement in aortic regurgitation or recurrent obstruction of the aortic valve or atrial septal communication. Occasionally, additional interventions have been performed in cases of technical failure or recurrent obstruction, but with very limited success (unpublished observations).

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