Balloon valvuloplasty for congenital heart disease in the fetus

Fetal intervention allows surgical correction or amelioration of known congenital defects in utero. With improvements in prenatal imaging and surgical techniques, fetal interventions have grown to include diagnoses associated with intrauterine demise, as well as diseases associated with significant postnatal morbidity. The goal of fetal intervention is to improve the chances of normal fetal development and minimize postnatal morbidity. Increasingly, advances have changed some procedures from open in-utero interventions, which are associated with significant maternal risk, to percutaneous or fetoscopic techniques, thus improving the maternal risk-to-benefit ratio while diminishing postoperative uterine contractions associated with open procedures. Fetal surgery often requires the anesthesiologist to care for two or more patients at once, all with distinctive and, at times, conflicting requirements. The first is the mother who can express her level of discomfort, who can be monitored directly, and to whom drugs can be administered easily. The second (and possibly third) is the fetus. For the latter, detecting pain depends solely on indirect evidence, monitoring is limited at best, administering drugs is more complicated, and there is the possibility of long-term effects from procedures and drugs administered during early development. The anesthesiologist is required to provide both maternal and fetal anesthesia and analgesia while ensuring both maternal and fetal hemodynamic stability; a plan must be prepared to resuscitate the fetus if problems occur during the intervention.

Fetal intervention allows surgical correction or amelioration of known congenital defects in utero. With improvements in prenatal imaging and surgical techniques, fetal interventions have grown to include diagnoses associated with intrauterine demise, as well as diseases associated with significant postnatal morbidity. The goal of fetal intervention is to improve the chances of normal fetal development and minimize postnatal morbidity. Increasingly, advances have changed some procedures from open in-utero interventions, which are associated with significant maternal risk, to percutaneous or fetoscopic techniques, thus improving the maternal risk-to-benefit ratio while diminishing postoperative uterine contractions associated with open procedures. Fetal surgery often requires the anesthesiologist to care for two or more patients at once, all with distinctive and, at times, conflicting requirements. The first is the mother who can express her level of discomfort, who can be monitored directly, and to whom drugs can be administered easily. The second (and possibly third) is the fetus. For the latter, detecting pain depends solely on indirect evidence, monitoring is limited at best, administering drugs is more complicated, and there is the possibility of long-term effects from procedures and drugs administered during early development. The anesthesiologist is required to provide both maternal and fetal anesthesia and analgesia while ensuring both maternal and fetal hemodynamic stability; a plan must be prepared to resuscitate the fetus if problems occur during the intervention.

Le cathétérisme interventionnel occupe une place croissante dans la prise en charge des cardiopathies congénitales. Depuis l’atrioseptostomie de Rashkind effectuée au milieu des années 1960 dans la transposition de gros vaisseaux, de nombreuses techniques ont émergé. Pour beaucoup d’entre elles, il s’agit de fermer avec un obturateur (double disque, bouchon, coil…) un shunt cardiaque ou extracardiaque qui induit le plus souvent un hyperdébit pulmonaire : fermeture de communication interauriculaire, de communication intraventriculaire, de canal artériel. Pour d’autres, il s’agit de lever un obstacle valvulaire ou vasculaire : dilatation de la valve pulmonaire ou aortique, voire d’une coarctation de l’aorte. Pour les sténoses vasculaires, l’angioplastie avec une sonde à ballonnet peut être associée à la mise en place d’endoprothèse. Enfin depuis une dizaine d’années, l’implantation de valve cardiaque est réalisée : tout d’abord la valve pulmonaire avec la valve Melody™ (Medtronic) ou la valve Sapien™ (Edwards Lifesciences), mais probablement à l’avenir la plupart des valves avec du matériel adapté en utilisant très souvent des techniques hybrides, c’est-à-dire combinant un cathétérisme avec une chirurgie. Les techniques de cathétérisme se sont aussi développées grâce aux progrès de la fluoroscopie qui peut actuellement être associée à d’autres techniques d’imagerie (échocardiographie, IRM ou scanner) afin d’accroître les informations sur le plan anatomique. Le cathétérisme interventionnel a encore de beaux jours devant lui avec le développement de nouveaux matériels ou techniques (3D « printing », « tissue engineering », nano-techniques). Il semble que d’une chirurgie à cœur ouvert, beaucoup de gestes pourraient à l’avenir être effectués à cœur fermé en associant le cathétériseur au chirurgien cardiaque et en créant ainsi une nouvelle discipline en cardiologie.

Interventional cardiac catheterization has a major place in the management of congenital heart disease. Since the Rashkind atrioseptostomy in mid-1960s, many techniques have been developed. For some, it is necessary to close a cardiac or extracardiac shunt using occluder (double disc system, plug, coil…): closure of atrial septal defect, ventricular septal defect or patent arterial duct. For others, it is necessary to treat a valvular or vascular stenosis using a balloon catheter: dilatation of the pulmonary or the aortic valve, dilatation of aortic coarctation. For vascular stenosis, balloon angioplasty may be associated with stent implantation. Moreover, since more than 10 years, valve implantation can be performed: initially for pulmonic valve (the Melody™ valve from Medtronic or the Sapien™ valve from Edwards Lifesciences); but probably, most of the valves in the future could be implanted using appropriate tools and hybrid techniques combining cardiac catheterization and surgery. All these techniques were developed because of progress in fluoroscopy, and more recently association of different imaging techniques (echocardiography, MRI and CT) provides more information about the true anatomy. Interventional cardiac catheterization will continue to increase with use of new tools as 3D printing, tissue engineering and nano-techniques. It seems that from correction with open-heart surgery, many lesions could be repaired in future by hybrid techniques without opening the heart.

Fetal surgery pushes the limits of knowledge and therapy beyond conventional paradigms by treating the developing fetus as a patient. Providing anesthesia for fetal surgery is challenging for many reasons. It requires integration of both obstetric and pediatric anesthesia practice. Two patients must be anesthetized for the benefit of one, and there is little margin for error. Many disciplines are involved, and communication must be effective among all of them. Conducting anesthetic research with vulnerable populations, such as the pregnant woman carrying a fetus with a birth defect is difficult, and many questions remain to be answered. Work is needed to study possible neurotoxicity caused by exposure of the developing brain to anesthetic agents. The effects of stress on the developing fetus also must be further delineated. Anesthetic techniques vary by institution, and prospective studies to determine optimal anesthetic regimens are warranted.

An early, primary, in utero cardiac abnormality may prevent normal heart development and cause irreversible secondary structural changes. The idea of foetal cardiac intervention stems from this understanding and focuses on antenatal intervention targeting the primary abnormality to allow normal flow and haemodynamics and thus normal heart development. Crucial aspects of foetal vascular access, varying foetal lie and structural complexity make it very hard to set procedural standards. The procedures are complex and are associated with significant maternal and foetal morbidity and mortality. The high risk-benefit ratio clearly explains the investigational nature of such therapies. With the development of minimally invasive techniques and continued animal experiments, foetal interventional therapy may see a low rate of morbidity and mortality, improving the prognosis of newborns with congenital heart disease previously considered incurable.

Une anomalie cardiaque précoce intra-utérine peut empêcher le développement normal du cœur et causer des changements structurels secondaires irréversibles. L’idée d’intervention cardiaque fœtale prend sa source dans la théorie du flux qui indique qu’une cavité se développe au prorata du sang qui la traverse. L’anomalie précoce est ici la réduction du flux, c’est-à-dire l’obstacle à l’éjection. Les interventions prénatales ciblent cette anomalie primaire pour permettre le rétablissement d’un écoulement et d’une hémodynamique normale et in fine d’un développement normal de cœur. Les procédures sont complexes, associées à une morbidité significative et à une mortalité maternelles et fœtales. Le rapport bénéfice/risque actuel en faveur du risque explique clairement la nature expérimentale de telles thérapies. Les résultats décevants sont expliqués par la difficulté d’accéder au mobile fœtal avec du matériel non dédié sur des malformations d’anatomie très variables dont l’histoire naturelle est mal connue et controversée. Avec le développement des techniques mini-invasives, de matériel approprié et des expérimentations animales, la thérapie interventionnelle fœtale pourrait voir ce rapport augmenter au bénéfice de la sécurité avec une réduction de la morbidité et de la mortalité, améliorant le pronostic des nouveau-nés avec la maladie cardiaque congénitale précédemment considérée incurable.