PRENATAL TREATMENT OF CONGENITAL HEART DISEASE By Dr. Bahar Dehghan Pediatric Cardiologist Isfahan University of Medical Sciences.

PRENATAL TREATMENT OF CONGENITAL HEART DISEASE

By Dr. Bahar Dehghan

Pediatric Cardiologist

Isfahan University of Medical Sciences

Background• It was postulated for many years prior to the

availability of ultrasound that certain congenital cardiac malformations evolve through the course of pregnancy.

• The potential benefits of fetal cardiac intervention (FCI) have been realized for many years.

• In 1975: intrapartum treatment of fetal V.T by administering propranolol to the mother.

• As early as 1986: in utero pacing for CHB in a human fetus.

• Recently, however, interest in FCI has accelerated.

• In 1992, Allan et al. reported an experience with a percutaneous technique for fetal aortic balloon valvuloplasty.

• Four fetuses were subjected to this technique, with a single long-term survivor.

• That technique was devised against a background of appalling survival figures for neonates undergoing surgical treatment for that lesion at that time.

• For conditions in which the fetus is at high risk for prenatal or neonatal death, the rationale for FCI is obvious, to improve survival.

• If death is not imminent but the disease is likely to have major lifelong morbidity, the rationale is that FCI will modify the course of cardiac growth, function, and/or development in utero sufficiently to alter postnatal outcome and justify the potential risks of the procedure.

Indications

1. Aortic stenosis2. Intact or restrictive atrial septum3. Pulmonary atresia with intact ventricular

septum (PA-IVS)4. Complete heart block with hydropse

Patient selection• These defects have a spectrum of severity and

usually progress during gestation, so the ideal time to treat them is before any additional insult is incurred.

• The ideal gestational age: when the patient meets criteria and as soon as possible.

• The ideal gestational age for treatment is therefore:

between 18 and 30 wks’ gestation for aortic stenosis, with 22-30 wk preferred for pulmonary valve

procedures, up to 34 wk preferred for an atrial septal procedure

in the presence of left heart obstruction.

• Whether invasive confirmation of a normal karyotype in the fetus is required is controversial.

• Noninvasive maternal serum testing should be performed and the fetus found to be euploid before intervention.

• Additionally, a detailed ultrasound examination should be performed to define:

other fetal anomalies placental location cervical length uterine or adnexal masses

that could influence the safety and technical aspects of the procedure.

• A thorough evaluation of the maternal health and obstetric history should be undertaken by an experienced maternofetal medicine specialist to rule out contraindications.

• The proposed procedure should also be discussed with the referring obstetrician/perinatologist who will be caring for the patient after the procedure.

• All patient counseling is preferably done with the partner or support person(s) present, and every effort should be made to ensure that there is an understanding of the issues regarding the procedure’s safety and efficacy for both the pregnant woman and the fetus.

Contraindications

• Significant preexisting maternal disease or obstetric comorbidity that would place the fetus or mother at higher risk, including:

anesthesia and the invasive procedure itself; a BMI exceeding 35 (relative contraindication);maternal communicable diseases such as HIV

infection, uncontrolled or pregestational diabetes (relative), history of cervical incompetence (relative),

hematologic disorders that affect coagulation,Significant extracardiac pathology in the fetus

(significant chromosomal abnormality and structural abnormalities other than the cardiac lesion),

Multiple gestation (relative), Inability of the mother to provide informed consent.

Patient Preparation• Maternal general anesthesia may be considered when a

laparotomy is planned. • Regional spinal anesthetic is almost always preferred,

with additional IV 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.

• Once maternal anesthesia is achieved, the patient is usually placed in a slight left lateral orientation.

• An ultrasound-guided technique using high-quality portable equipment.

• Initially, the obstetric sonographer reassesses the fetal lie to plan the optimal access site.

• Fetal movement may make these procedures technically more difficult.

• 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 US guidance.

Complications• Isolated maternal anesthetic risks, however small,

depend on the mode of anesthetic used include maternal cardiovascular compromise with respiratory distress and pulmonary edema.

• Placental abruption and resultant maternal hemodynamic compromise because of uterine manipulation to achieve optimal fetal positioning.

• Preterm labor (10%), after the procedure with a possible need for maternal hospital admission and monitoring for implications of tocolysis.

• PROM (2% risk) may lead to a uterine infection, for which maternal antibiotic therapy is required.

• Transient bradycardia (10-40%) due to needle puncture of the fetal heart and needle manipulation during the procedure.

• Severe sustained fetal bradycardia and dysfunction have been noted, requiring intracardiac or IM resuscitative medications.

• Hemopericardium, occasionally, pericardiocentesis is necessary for impacting cardiac output.

• Intracardiac thrombus formation and loss of catheter tip have also been reported.

• Higher incidence of fetal loss (10%) after the procedure than for pregnancies continuing without invasive intervention.

• Generally, there is no change in the mode of delivery after cardiac surgery in utero, and delivery plans are made on the basis of the usual obstetric indications.

Technical limitations or failures of fetal interventions

• Although it is evident that technical success is possible for fetal aortic and pulmonary valvuloplasty and atrial septoplasty, universal adoption of in-utero treatment for all fetuses is not appropriate.

• The level of care both in the obstetric environment and for NICU may not be available at all institutions.

• Currently, the practice of FCI is confined to a few institutions that have invested a great deal of time and effort in research, development, and refinement of technical expertise in this area.

• Technical issues related to fetal positioning, stabilization, and the need for continuous imaging by specially trained personnel with experience in US guidance of invasive procedures.

• Equipment-related limitations, including imaging artifacts caused by the materials used to manufacture the needles, wires, and catheters, exacerbated by the diminutive sizes of the cardiac structures being imaged.

Future directions• Given the relative rarity of these fetal congenital

heart conditions, more collaborative effort is necessary in order to improve our procedural techniques and to achieve an acceptable safety level for both the mother and fetus.

• It is also essential to continue efforts to improve equipment technology for diagnostic imaging and in the procedure room.

• One potentially important advance may come in the form of sophisticated robot-guided FCI.

• Fetal therapy for congenital heart conditions is an area that holds great promise in the management of complex cardiac disease.

“Thank You For Your Attention”