E H A RT M U R M U R S
SPRING/SUMMER 2003 A PUBLICATION FOR PHYSICIANS & NURSES ABOUT THE CARDIOVASCULAR PROGRAM AT CHILDREN'S
TO
SURGICAL ROBOTICS COMES T H E C A R D I A C O P E R AT I N G R O O M
BY PEDRO J. DEL NIDO, MD CHIEF, CARDIAC SURGERY
movements the surgeon wants to perform and to translate these to an instrument that is controlled by the computer (see figure below). The advantage of this type of advanced instrumentation is that it not only replicates the surgeon's every move precisely, but also can enhance the movements by scaling them to very small spaces. Thus, the same operation that is usually performed with the body cavity open can
From the very earliest procedures, surgeons have sought to develop and optimize instruments to facilitate operations. As the complexity and variety of procedures has increased, so has the variety and complexity of the surgeon's tools or instruments. No procedures have demanded more complicated and precise instruments than current techniques for minimally invasive repair of defects inside the abdomen or chest cavity; and no procedures have presented so strong a need for a clear and highly detailed "image" of anatomic structures inside body cavities to permit precise instrument navigation and tissue reconstruction. These obstacles are even greater when the "imaging" required is inside an organ such as the heart, which is filled with blood, making optical methods impossible. For an organ that moves rapidly, the image obtained must not only be highly detailed but also "real-time" to provide the surgeon with accurate anatomic details "live." Similarly, the surgical instruments must be capable of functioning with precision within these rapidly moving structures. With advances in computers and imaging technology, many of these obstacles are now being overcome.
CONTINUED ON PAGE 2
F E TA L C A R D I A C INTERVENTION
BY AUDREY C. MARSHALL, MD INSTRUCTOR IN CARDIOLOGY
After years of leadership and innovation in the care of children born with congenital heart disease (CHD), doctors from the Cardiovascular Program are now extending their therapeutic reach into the heart of the fetus. A team comprising specialists from Children's Hospital, Boston, and Brigham and Women's Hospital has successfully performed fetal intervention to treat congenital heart defects. Since our first attempt in March 2000, we have performed 15 fetal interventions, including 11 aortic valve balloon dilations, creation of three atrial septal defects and one pulmonary valve dilation.
Introduction of Computer-Aided Instrument Control
The most recent advance in surgical instrumentation is the incorporation of computer-aided instrument control, more commonly known as "surgical robotics." This term refers to the application of computer technology to sense the
Averting Development of Hypoplastic Left Heart Syndrome Position Commands Surgeon
Master Controller Surgical Robot
Patient
Force Feedback
Monitor
Video Robot
The field of fetal surgery is guided by the principle that early fetal intervention may prevent the maldevelopment associated with some anatomic defects, thereby averting postnatal disease. In cases of established fetal malformation, intervention may also be pursued to modify prenatal conditions to enhance postnatal outcome. Our fetal cardiac intervention team from Children's Hospital, led by Dr. James Lock, has concentrated in particular on attempts to avert the development of hypoplastic left heart syndrome (HLHS) by early balloon dilation of critical aortic stenosis or to modify
SURGICAL ROBOTIC SYSTEM
CONTINUED ON PAGE 5
SURGICAL ROBOTICS CONTINUED FROM PAGE 1
SURGEON'S
MASTER CONTROLLER
now be done with the use of computerenhanced micro-instruments through an incision or "port" just large enough to fit the small instrument. Since the early 1990s robotic systems have been developed for use in surgical procedures ranging from laparoscopic surgery to orthopedic procedures, and more recently to cardiac surgery in adults. The earliest
Heart Murmurs
Editors: Patricia A. Hickey, RN, MS, MBA Peter C. Laussen, MBBS Published twice a year by the Cardiovascular Program at Children's Hospital Boston 300 Longwood Ave. Boston, MA 02115
Masthead drawing by Carolyn Lock
instruments performed relatively simple tasks, such as voice-controlled movement of a scope or retractor. In the last four years, however, the next generation of instruments has arrived that can perform more complex movements that imitate the motions of the human wrist. This particular advance has permitted the use of robotics in surgical reconstructive procedures and has opened the doors for more complex operations to be performed that are minimally invasive. The use of robotic manipulators as an extension of the human hand grew out of an interest in performing extremely dangerous tasks from a remote location. Subsequent advances in mechanical design, kinematics, control algorithms and programming have facilitated application of this technology to a variety of surgical interventions.
ROBOTICS
IN THE OPERATING ROOM
We'd like to hear from you
If you wish to refer a patient, receive a consultation or seek information about our program, please contact us by phone or e-mail. Patricia A. Hickey, RN, MS, MBA [phone] [e-mail] Richard A. Jonas, MD [phone] [e-mail] Peter C. Laussen, MBBS [phone] [e-mail] James E. Lock, MD [phone] [e-mail] Visit our web site www.childrenshospital.org
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Pediatric Applications of New Technology
In pediatrics, application of this technology has been slowed by a lack of available instruments appropriate for small children. Despite these obstacles, surgeons have developed techniques for minimally invasive surgery to treat a wide variety of defects, including cardiac anomalies. Children's Hospital, Boston, has been at the forefront of this technology development and was the first pediatric center to obtain a surgical robotic system (see photographs above). The first clinical procedures
were performed in March of 2002; since then, faculty from the Departments of Urology and Cardiac Surgery have carried out many robotic-assisted operations. Currently, cardiovascular applications have been confined to surgery on blood vessels in the chest, e.g., ligation of a patent ductus arteriosus. In the next few months, the robotic system will also be used for intracardiac procedures. The application of cutting-edge technology is supported and promoted by emerging advancements in areas such as live 3-D ultrasound, which allows real-time, non-invasive imaging of intracardiac structures, led at Children's by Dr. Gerald Marx, Department of Cardiology. Paralleling the clinical activities is an active research effort to develop new applications of the current system and to devise new instruments specifically designed for use in children. Children's is also the first pediatric center to have purchased a robotic system dedicated exclusively for research and development as well as for training of surgeons in robotic surgery. n
PEDRO J.
DEL
NIDO, MD
To view a robotic procedure go to www.childrenshospitals.net/nachri/aboutn/cht%5Fsummer02%5Frobotic.html
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" A USTRALIAN T ECHNIQUE " R EPAIR FOR C OMPLETE AV C ANAL I NTRODUCED AT C HILDREN ' S H OSPITAL B OSTON
BY RICHARD A. JONAS, MD, CARDIOVASCULAR SURGEON-IN-CHIEF
Complete common AV canal is a complex congenital cardiac anom-
Early Efforts to Achieve Repair
The first repair of complete AV canal was performed in a child by C. Walton Lillehei in Minnesota in the early 1950s. This was a remarkable achievement for the time since the repair pre-dated the use of the heart-lung machine. Dr. Lillehei utilized cross-circulation in which a parent functioned as the "oxygenator" to support the child during the openheart procedure. The first report of successful repair of complete AV canal during infancy was achieved
aly that has challenged cardiac surgeons for many years. Failure of complete endocardial cushion tissue development results in the presence of a large ventricular septal defect (VSD) and atrial septal defect (ASD). In place of two inlet valves--the mitral and tricuspid--there is a single common valve. Surgical repair of this anomaly necessitates closure of the ASD, closure of the VSD, and reconstruction of a mitral and tricuspid valve from the common atrioventricular (AV) valve.
by Sir Brian Barratt-Boyes in New Zealand in 1973. Since the 1970s there has been ongoing controversy regarding the best technique to repair complete AV canal. The method used by Dr. Aldo Castaeda at Children's Hospital in Boston during the 1970s and 1980s is the so-called traditional single-patch technique. Some of the patient's own pericardium is harvested and the common AV valve is divided over the top of the ventricular septum. The patch is sutured to the top of the ventricular septum as well as to the edges of the atrial septal defect. The mitral and tricuspid valves are reconstructed by reattaching the delicate leaflets to the pericardial patch. An alternative method known as the two-patch technique places a separate patch to close the VSD under the common AV valve, with another patch used to close the
THE "AUSTRALIAN TECHNIQUE" FOR REPAIR OF COMPLETE AV CANAL INVOLVES PLACEMENT OF MULTIPLE
INTERRUPTED PLEDGETTED SUTURES ON THE RIGHT SIDE OF THE CREST OF THE VENTRICULAR SEPTUM.
THESE
SUTURES ARE PASSED THROUGH THE SUPERIOR AND INFERIOR COMMON LEAFLETS AND THEN THROUGH AN AUTOLOGOUS PERICARDIAL PATCH.
3
atrial septal defect. Both patches must be attached to the delicate leaflet tissue. The disadvantage of these methods of complete AV canal repair is that there is risk of distortion of the leaflet tissue by the sutures, which must be used to insert the patches. The twopatch technique presents a risk that the leaflet tissue may tear away from the patch, leaving leakage of the valves. This is particularly true of the mitral valve, which functions at approximately five times the pressure of the tricuspid valve. Late problems with the mitral valve, including need for replacement, have been seen with disappointing frequency.
Technique Offers Important Modification
Ian Nicholson and Graham Nunn, two Australian graduates of the International Fellowship program of the Department of Cardiovascular Surgery at Children's Hospital, Boston, who now work together in Sydney, Australia, described a modification of the single-patch technique in Boston in 1997 and published their findings in 1999. The technique varies from the traditional single-patch method in that the common AV valve leaflets are brought down to the crest of the ventricular septum (see figure right). This method has great advantage since little manipulation of the leaflet tissue is required and thus the repair can be undertaken in very small infants and even newborns, who have particularly delicate tissue. leaflet The Australian technique was introduced at Children's Hospital, Boston, by Dr. Richard Jonas, Cardiovascular Surgeon-in-Chief, in 1997 and has been applied in 31 patients up to October 2002. (The results will be presented by Dr. Bassem Mora, Associate in Cardiac Surgery, at the spring meeting of the American Association of
Thoracic Surgery, to be held in Boston in May 2003.) The average weight of the infants who underwent this technique was 5.6 kg and their median age was three or four months. Several patients had an unbalanced AV canal with either the right ventricle or left ventricle being dominant. In 68 percent of patients the common AV valve already had mild regurgitation, in 15 percent it was moderate, and in 3 percent it was severe. No patient died after surgery and no patient developed left ventricular outflow tract obstruction or required reoperation for regurgitation of the mitral valve. One patient required a pacemaker and one needed a period of support with ECMO (extracorporeal membrane oxygenation). Function of the mitral valve by postoperative echocardiography was very satisfactory, with 13 percent of patients having no mitral regurgitation, 63 percent with
mild, 23 percent with moderate, and none experiencing severe regurgitation. The results on follow-up echocardiograms were equally encouraging. The Australian technique for repair of complete AV canal has resulted in very promising outcomes in both Sydney and Boston. Careful monitoring of these patients is continuing. Based on the longer-term results from Sydney, it appears that the incidence of late problems is remarkably low. This new technical modification will be an important advantage for small babies, who will now be able to undergo repair of complete AV canal very early in life. n
RICHARD A. JONAS, MD
TYING
THE
THE SUTURES PLACED IN THE VENTRICULAR CREST
AS PART OF THE
AUSTRALIAN
TECHNIQUE OBLITERATES
VSD
BY BRINGING THE COMMON
AV
VALVE LEAFLETS
DOWN TO THE CREST OF THE SEPTUM.
4
FETAL CARDIAC INTERVENTION CONTINUED FROM PAGE 1
certain forms of HLHS, such as balloon dilation of a restrictive atrial septum. HLHS is one form of cyanotic CHD that is uniformly fatal if untreated. Results of staged surgical palliation, first attempted in the 1980s, have steadily improved. Current survival to discharge at Children's Hospital, Boston, following the Norwood procedure is 89 percent over the last two years. Despite improvements, the outcomes for many of these infants remain poor as compared to results for most other cardiac defects and require a staged surgical management until achieving a physiologic repair with the Fontan operation. This repair usually occurs over a two-year period, and longer-term development and growth may be compromised. Because of the limitations imposed by single ventricle cardiac defects, fetal intervention offers the prospect of possible two-ventricle development. Aortic stenosis is believed to be a relatively frequent etiologic lesion in the development of HLHS. When the aortic valve, which is the only source of outflow from the fetal left ventricle, becomes obstructed, the ventricle becomes pressure-loaded and develops muscle failure and muscle death. While the rest of the heart, including the right ventricle, continues to grow through gestation, the left ventricle remains a tiny, functionless cavity. Therefore, early intervention at 20 to 24 weeks' gestation to relieve severe fetal aortic stenosis may allow normal development of the heart, particularly the left ventricle, to proceed.
DIAGRAMMATIC
VIEWS OF FETAL
AORTIC VALVE DILATION
First Fetal Aortic Valve Dilation
Drawing on the resources of the Advanced Fetal Care Center at Children's as well as the input of specialists at Brigham and Women's, we attempted the first fetal aortic valve dilation in March 2000. The team assembled for this procedure included pediatric cardiologists, perinatologists, obstetricians, obstetric ultrasonographers, obstetric and fetal anesthesiologists, and fetal surgeons. Over the course of 15 cardiac fetal interventions, only slight adjustments to equipment and technique have been necessary. First, the mother is placed under general anesthesia in order to have complete maternal abdominal and uterine relaxation. In some cases, the procedure can be performed entirely percutaneously. Alternatively, a small, low transverse abdominal incision is made, and the uterus is entered under direct visualization. A tiny needle is passed through the uterus into the fetus' thigh or buttock to administer fetal anesthesia, ensuring that the fetus will be still and pain-free throughout the remainder of the procedure. Next, this tiny needle is removed and a slightly larger one is used to perform the actual dilation procedure. Once the needle has traversed the uterine wall and the fetal chest wall, it can be introduced into the fetus' dilated left ventricle. Radiologists follow the intra-abdominal needle course using 2-dimensional ultrasound imaging. With the tip of the needle in the LV, a tiny balloon dilation catheter is advanced through the needle. As the tip of the dilating catheter approaches the tip of the needle, a fine wire is advanced through the catheter and directed across the stenotic aortic valve. This wire acts as a rail to guide the balloon catheter across the valve. Once the balloon position
is confirmed, the sausage-shaped balloon is inflated to dilate the valve (see figures above and right). Some neonates with HLHS have a subtype associated with an intact or restrictive atrial septum, which will reduce mixing of systemic and pulmonary venous blood and cause pulmonary venous hypertension. At birth, they may be extremely cyanotic and progress rapidly to circulatory collapse. Immediate intervention in the catheterization laboratory with creation and balloon dilation of a hole in the atrial septum is lifesaving. Following this intervention, these patients can be medically stabilized over several days prior to the initial Norwood procedure. In an effort to create a more controlled situation for these infants postnatally, the fetal cardiac intervention team has attempted two procedures to create a hole in the atrial septum of fetuses diagnosed with HLHS and intact atrial septum. While both of these procedures have been technically successful, more cases are necessary to determine whether this fetal intervention will have the desired effect of providing early hemodynamic stability, and subsequent improved outcomes.
Refining Techniques of Fetal Intervention
Over the last three years, the team from Children's Hospital and Brigham and Women's Hospital has become a leader in the emerging field of fetal cardiac intervention. This intervention is a dramatic and exciting new development in the management of congenital heart disease, although we can never lose sight of the potential severe risks to both mother and fetus. Our team continues to strive to refine techniques and identify indications for fetal cardiac intervention. Technical success has allowed us to test disease hypotheses; for example, can fetal aortic valve dilation allow development of the left ventricle and avoid HLHS? For the team, the greatest inspiration is provided by patients such as Jack, who was born with a healthy heart and two ventricles after balloon dilation of his aortic valve at 23 weeks for evolving HLHS. n
AUDREY C. MARSHALL, MD
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Cardiovascular Program Bereavement Review Council:
A FORUM
FOR
S TA F F E D U C AT I O N
AND
S U P P O RT
BY DOROTHY M. BEKE, RN, MS, CPNP CLINICAL NURSE SPECIALIST , AND PATRICIA HICKEY, RN, MS, MBA,VICE PRESIDENT, CARDIOVASCULAR AND CRITICAL CARE SERVICES
Nurses and physicians in the Cardiovascular Program (CVP) at Children's Hospital, Boston, have many opportunities to influence the quality of care that patients and families receive. While they are responsible for providing technological advancements and innovative treatments, they also need to humanize the hospital environment and offer compassion and support for patients, families and staff. Improving endof-life care and providing a forum for staff education and support around bereavement and challenging care issues are important priorities. To facilitate this process, a CVP Bereavement Coordinator was recently appointed in conjunction with the establishment of the Bereavement Review Council. The mission of the Bereavement Review Council is twofold: 1) to facilitate a holistic approach in helping families cope with death, dying and/or critical illness, and 2) to provide appropriate resources, guidance and support for staff. These objectives are achieved through biweekly, interdisciplinary rounds that focus on education, team communication, open expression of concerns, and staff debriefing. Ultimately, the Council's role is to support staff while increasing their comfort level and expertise in assisting families through critical illness, death and dying. The Council also discusses management issues and concerns as they arise for long-term CICU patients to prevent miscommunication and avoid subsequent conflict or misunderstanding. Since August of 2002, interdisciplinary participation has been crucial as staff gather to discuss challenging patient cases. Dorothy Beke, RN, CVP Bereavement Coordinator, and David DeMaso, MD, Associate Psychiatrist-in-Chief, facilitate the group discussions. Nurses, physicians, social workers and child life specialists have all presented interesting case studies from the recent past or those in process. Among the topics for forthcoming case presentations are issues regarding health care proxy and advanced directives
for adults in a pediatric institution, futility in care, facilitating a spiritual assessment of the patient and family, and coping mechanisms for clinician stress. In the CVP the Bereavement Review Council provides a , creative solution for staff education and support around end-of-life and complicated care issues. When staff are able to comfortably express their feelings in a supportive group, they are better able to understand the complexities involved in emotionally charged situations. By discussing strategies for specific challenges, the care providers are more confident and effective in planning and implementing care for all DOROTHY M. BEKE, PATRICIA HICKEY, patients and families. n
RN, MS, CPNP RN, MS, MBA
Coming Up
THE FOLLOWING MEETINGS HAVE BEEN SCHEDULED BY THE CARDIOVASCULAR PROGRAM. I May 13, 2003 Frontiers in Diagnosis and Management of Congenital Heart Disease, Enders Auditorium, Children's Hospital Boston I May 3, 2003 Society of Pediatric Cardiac Surgery, Aldo R. Castaeda, Enders Auditorium, Children's Hospital Boston I June 27 and 28, 2003 Prenatal Cardiac Intervention, Enders Auditorium, Children's Hospital Boston For further information, please contact Kathy Milligan, [phone], by e-mail [e-mail].
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