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Video-Assisted Endoscopy for Congenital Heart Repair
Video-Assisted Endoscopy for Congenital Heart Repair Redmond P. Burke Endoscopic imaging techniques can be used to enhance visualization of and access to remote intracardiac structures to improve congenital heart repairs. Database storage of these images builds a foundation for retrospective analysis of surgical failures and clinical correlations with other imaging techniques. The images also function as an educational tool for patients, families, and the cardiac team. Combining cardiac endoscopic imaging with interventional catheterization techniques has created a group of hybrid procedures, extending the capabilities of both the surgeon and the interventional cardiologist. This synergy has the potential to decrease therapeutic trauma. Copyright © 2001 by W.B. Saunders Company
Key words: Cardioscopy, minimally invasive surgery, video-assisted thoracoscopic surgery, endoscopy, interventional catheterization, congenital heart surgery, intraoperative stents.
may be defined as the use of C ardioscopy endoscopic imaging during open-heart
procedures to enhance the visualization and repair of remote intracardiac structures. Experience with video-assisted thoracoscopic techniques for extracardiac lesions, such as patent ductus arteriosus ligation, intuitively led investigators to begin using direct videoassisted cardioscopy during open-heart repairs. 1 Video-assisted cardioscopy allows surgeons to achieve anatomic visualization without resorting to excessive retraction or extended cardiac incisions. Cardioscopy provides the entire operative team with an image of the defect and allows immediate assessment of the efficacy of repair. Additionally, video-assisted endoscopic imaging has proven to be advantageous during minimally invasive procedures by enhancing visualization in the operative field when operating through small incisions. Cardioscopy also has formed a platform for combined or hybrid procedures using both transcatheter From the Division of CardIOvascular Surgery, };fzaml Children's Hospital, Miami, FL. Address rtprint requests to Redmond P. Burke, MD, Division of Cardiovascular Surgery, Miami Chlldrtn's Hospital, 3200 SW 60 Court, Suite 102, Mzami, FL 33155-4069. Copyright © 2001 by WB. Saunders Company 1092-9126101/0401-0018135.0010 doi: 10.JO.53Ipcsu.2001.246.52
208
techniques and minimally invasive surgery. We anticipate that an expanding array of new procedures will emerge in the coming years, guided by various forms of video-assisted cardioscopy.
Technique Intraoperative cardioscopy is performed with the same endoscopic video-assisted equipment used for extracardiac repairs. Cardioscopy was initially used selectively, when difficult exposure was anticipated. However, the need for remote visualization during congenital heart repair is unpredictable, so we now use the technique routinely during every operation. The cardioscope has become a common eye for the cardiac team, allowing everyone in the cardiac operating room to see into the cardiac chambers. Routine use has allowed the scrub technicians to become comfortable with the equipment, and to create a consistent practice plan for cardioscopy and image acquisition. By enabling the cardiac team to see the operation in progress, team members are able to anticipate necessary actions, which has increased operative efficiency. A mechanical arm can be used to stabilize the camera in the operative field and free the surgeon's hands. \Ve now position the endoscope at the foot of the pa-
Pediatric Cardiac Surgery Annual ojthe Seminars
In
Thoracic and Cardiovascular Surgery, Vol 4, 2001: pp 208-215
Video-Assisted CardioJcop)'
209
Figure 1. Ope rative setup for intraoperative cardioscopy. tient's bed, in the operative field, where it can be rapidly passed to the surgeon like any other instrument (Fig I) . The cardioscope path into the operative field is determined by the patient's anatomy. A variety of approaches (aortic, pulmona ry, right atrial, left atrial, and through septal defects) are possibl e. Every cardiac chambe r and great vessel , the pulmonary veins and all valves can be exposed with the cardioscope. The pleural spaces also can be explored through partial or full sternotomy. Our experience with cardioscopy has enabl ed us to develop a protocol for documenting cardiac operatio ns and managing ope rative images . W e routinely begin ope n-h e art procedures by capturing images of any important external cardiac a natomy with th e endoscope . We th e n commence exposur e of th e cardiac defect, with or without cardiopulmonary bypass, and again document th e anatomy with the
cardioscope, looking for un expected anatomic variants or potential problems, planning suture lines, and sizing baffles and patches. The cardiac repair is peI"furmed, with intermittent cardioscopic assistance to e nsure precision. Once th e defects have b ee n repaired, compl e tion images are obt a ined, and thc ope ration s are completed. In minimally invasive repairs, rul e rs arc placed on the incision s to document incision length. From the series of intraoperative images coll ected during each ope ration, luur images are selected by the surgeon to show the cardiac anatomy before and after repair. Foul' print copies an~ made , Ollt' for the patient and famil y, one fur the re ferring physician, one for the patient's ch a rt , and one for the \\-'ee kly morbidity a nd mort ality conference . At this conference all intraoperatiVl' imag-cs are revi ewed and correl a ted with pre operati\'e imaging techniques (eg, echocardiogra-
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phy, magnetic resonance images, angiograms) and postoperative events.
Clinical Applications We recently summarized our experience with routine cardioscopy for congenital heart repair.2 From 1995 to 1999, we used intraoperative cardioscopy in 409 consecutive patientsundergoing open-heart repairs. Cardiascopy was used to facilitate and document the repair of the following lesions: ventricular septal defects (VSD), tetralogy of Fallot, double outlet right ventricle, atrioventricular canal, subaortic stenosis, valve repair, Rastelli and Rev procedures, Konno and Ross-Konno operations, and a variety of other complex repairs. Cardioscopy provided excellent visualization in each case without significantly prolonging operative times. Intraoperative images were collected for the cardiac surgery database, documenting each child's anatomy before and after repair. Surgery through small incisions was facilitated. Operative mortality was 1.2% and no patients required reoperations before discharge. There were no complications related to cardioscopy. At a mean follow-up of 22 months, there was a 1.2% incidence of reoperations for residual or recurrent lesions. We concluded that routine use of the technique was feasible and potentially useful. Other investigators have described similar experiences with routine intraoperative cardioscopy. Reuthebuch et aI3 describes an experience in 100 patients, using a 5 mm flexible or rigid cardioscope to visualize a wide variety of cardiac lesions, and reported no complications related to the technique. Cardioscopy is particularly useful for VSD repair. Reliance on transesophageal echocardiography to ensure complete closure necessitates going back on bypass and reopening the heart when residual defects are detected. Cardioscopy may show residual defects before atrial closure, allowing immediate repair. For perimembranous defects, the scope is advanced through the right atrium and the
tricuspid valve immediately after cardiac arrest is initiated. A determination is made as to the need for detaching the anterior leaflet of the tricuspid valve to improve exposure. A pericardial patch is placed with running suture, and any concern about proximity to the aortic valve leaflet, the conduction system, or any muscle folds that might produce a residual defect can be seen with the cardioscope. Muscular defects can be exposed endoscopically, and direct or device closure can be guided. We reported our experience with 150 VSDs of all types in patients weighing from 2.3 kg to 76.8 kg.2 Follow-up echocardiography by both transesophageal echocardiography and postoperative transthoracic echocardiography showed small residual VSDs in only 12 patients (seven of these had multiple defects preoperatively), and no patients required reoperation. There was no control experience without cardioscopy to allow us to conclude that cardioscopy reduced the incidence of residual defects after VSD repair. We also have been pleased with the utility of cardioscopy for valve procedures. We described 50 patients undergoing valve repairs as part of their congenital heart procedures. 2 These patients ranged in weight from 3.5 kg to 80 kg (mean, 21.2 kg). Before and after repair, valve competence was tested by saline infusion, after removing atrial retractors, to create a more normal approximation of valvar anatomic relationships. One patient was found to have severe left-sided atrioventricular valve insufficiency after complete atrioventricular canal repair and underwent valve replacement. At a mean follow-up of 22 months, no patients required reoperation for valvar pathology. Figure 2 shows the intra· operative images of a left-sided atrioventricular valve in a patient who had undergone atrioventricular canal repair as an infant and subsequently presented to us with valvar insufficiency. The second image in Fig 2 shows the valve immediately after repair, which was effective. Numerous creative clinical applications of intraoperative cardioscopy have now been re-
Video-Assisted Cardioscopy
ported. Bauer et al 4 used transaortic cardioscopy to explore the left ventricle, thereby avoiding the need for ventriculotomy. In a subsequent report, Bauer et al'> used cardioscopy to facilitate resection of hypertrophic left ventricular myocardium. Cardioscopy also has been used to diagnose and treat left ventricular outflow tract obstruction related to a mitral valve prosthesis.!) Greco et al 7 recently excised a left ventricular myxoma using transaortic video-assisted cardioscopy. We reported resection of a left ventricular thrombus in a 17-year-old girl with viral myocarditis and cardiomyopathy.s
Cardioscopy in Minimally Invasive Surgery Several investigators have described using cardioscopy as an adjunct to surgery through limited incisions. Rao et al 9 described using cardioscopy to facilitate atrial septal defect repairs through partial lower sternotomy. Cardioscopy addresses one of the crucial limitations inherent in these procedures - compromised visua1ization. We have found this particularly true for subaortic membrane resection, in which cardioscopy allows magnification of the left ventricular outflow tract from the aortic incision down to the ventricular apex. At Miami Children's Hospital, we approach this lesion using a 4-cm partial upper sternotomy and a combination of endoscopic guidance and direct vision. Beginning in March 1997, 15 patients with subaortic stenosis, ranging in age from 2 to 16 years (mean, 6.7 years) and in weight from 12.0 kg to 65.0 kg (mean, 26.0 ::!: 13.8 kg), underwent repair. There were 10 boys and five girls. All patients were diagnosed with subaortic fibromembranous stenosis by eehocardiography. Four patients had mild aortic regurgitation. Their preoperative systolic pressure gradient between left ventricle and aorta measured by echocardiography ranged from 25 to 125 mmHg (mean, 55.1 ::!: 22.S mmHg). Incisions ranged from 4.0 em to 9.0 cm (mean, 5.3 ::!: 1.6 cm). Mean operation time (defined as the
211
time from skin incision to wound dressing) was 153.7 ::!: 36.2 minutes (range, 115 to 225 minutes). Mean cardiopulmonary bypass and cross clamp times were 68.0 ::!: 15.9 minutes (range, 50 to 113 minutes) and 42.1 ::!: 14.8 minutes (range, 20 to 77 minutes), respectively. Mean postoperative systolic pressure gradient between left ventricle and aorta measured by echocardiography was 6.1 mmHg and there was no pressure gradient in 11 patients (73%). Twelve patients (80%) were extubated in the operating room. There were no hospital deaths and no postoperative complications. The duration of hospital stay was 3.1 ::!: 1.4 days (range, 2 to 7 days). Mean patient follow-up is 15.3 months, ranging from 2.1 months to 27.1 months, and we have seen no deaths or reoperations. Cardioscopy does have technical limitations; condensation or blood can cloud the lens, the equipment requires sophisticated maintenance to maintain a high quality image, bypass and arrest time is consumed, and even the best image lacks depth perception. With training, the operating team can become facile with the endoscopic equipment, and our mechanical failure rate in the operating room for image acquisition has been zero. Endoscopy does provide increased magnification over conventional surgical lou pes, up to four times normal, and the ability to use angled or flexible fiberoptic scopes enable the team to look around corners and into deep recesses and vessels within the heart.
Experimental Applications A variety of laboratory applications for direct endoscopic and remote fiberoptic cardioscopy have been described. In 1991 , Uchida et altO described transcatheter fiberoptic endoscopy to obtain direct video images of the beating endocardium. In 1994, Legget and Shawl I suggested a technique for fiberoptic cardioscopy. This technique was limited by difficulties with flushing the heart with clear
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Figure 2. (Left) A cardioscopic image of a badly deformed and insufficient left-sided atrioventricular valve in a 2-year-old child. (Right) A postrepair image of the valve showing competence with saline infusion.
sten\
Left Pulmonary Artery
Cardioscope Balloon Catheter
Figure 3. Intraoperative pulmonary artery stenting with cardioscopic guidance.
Video-Assisted Cardioscopy
fluid to allow visualization, but suggested the possibility of percutaneous endoscopically guided heart repairs. Inoue et al 12 described fiberoptic endoscopy for laser valvuloplasty in an animal model, although there were problems with maintaining position within the beating heart. More recently, Inoue et al 13 described the potential usefulness of a combination of transthoracic radiofrequency catheter ablation with video-assisted thoracoscopic and cardioscopic linear ablation of atrial fibrillation pathways. The technique was presented as a possible future off pump alternative to the Maze procedure. Seward et aP+ described a device for ultrasound cardioscopy with balloon displacement of intracardiac blood as a promising means of performing precise under-blood diagnostic and therapeutic maneuvers in an animal study of catheter ablation. Yamamoto et aps also described using a balloon-tipped cardioscope, in their investigation, to visualize the right atrial posterior septum and guide an electrode catheter into the coronary sinus in dogs. Kohl et al 16 describes remarkable work with fetal sheep to assess the feasibility of fetoscopic and open transumbilical fetal cardiac catheterization, guided by fetal transesophageal echocardiography, to provide alternative approaches for human fetal cardiac intervention.
Hybrid Procedures: Combining Cardioscopy and Transcatheter Intervention Interventional cardiologists were initially chagrined that cardioscopy was very efTective at documenting technical failures in the catheterization laboratory, such as stent migrations and septal device misplacements, but this concern has largely subsided. There is now significant interest in developing hybrid techniques combining transcatheter techniques with intraoperative cardioscopy. Transcatheter endovascular stent implantation is an effective modality for treating branch pulmonary artery stenoses. However,
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a subgroup of patients with branch pulmonary artery may benefit from direct intraoperative placement of these prostheses. Intraoperative stent placement may be limited by poor visualization of the target lesion and the relationship between the distal stent and pulmonary artery side branches. Visualization may be particularly difficult when the stent must be placed behind the aorta or distally in the branch pulmonary artery. We hypothesized that video-assisted cardioscopic guidance of stent placement would improve visualization and increase the accuracy of stent positioning and deployment in the operating room. We prospectively collected and analyzed data on 11 consecutive children undergoing intraoperative branch pulmonary artery stent implantation with video-assisted cardioscopic guidance. Success was defined as complete relief of stenosis as well as avoidance of occlusion of any major secondary pulmonary artery branches. The technique is demonstrated in Fig 3. All patients were on cardiopulmonary bypass at the time of videoassisted cardioscopic guidance. Fourteen stents were implanted in 11 patients with a success rate of 93% (13/14). Mean age and weight were 53.7 months (range, 16 days to 150 months) and 14.1 kg (range, 2.1 to 31.5 kg). Ten of the 11 patients (91 %) were reoperations. Stents were placed during associated surgery in seven patients because of failed percutaneous stent placement in two and for inability to wean from cardiopulmonary bypass in two. Diagnoses included pulmonary atresia with VSD in nine patients, and one each with truncus arteriosus and tetralogy of Fallot with discontinuous left pulmonary artery. The single stent placement failure was secondary to interference from a previously placed stent, which required surgical removal and patching. Early follow-up (mean, 15 months) showed one death secondary to sepsis. There were no late complications or reinterventions required. Our preliminary conclusion is that cardioscopic guidance of intraoperative stent
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placement is straightforward and offers valuable visual assistance during intraoperative stent placement. Cardioscopy also has been used to reposition septal occlusion devices placed in the catheterization laboratory, I and could be used for elective intraoperative device placement during complex multilesion repairs.
Robotic Video-Assisted Surgery Converging advances in technique and technology may allow robotic endoscopic open heart procedures to be performed, however, there are daunting technological challenges to address. Because of size constraints, clinical applications of robotic heart surgery have been limited to adult patients. Coronary artery bypass,17 internal mammary artery harvest, 18 and mitral valve repair,19 have been described in human applications. Several companies are building their conception of the futuristic operating rooms based on robotic surgery. These include "The Intuitive Surgical System," which consists of the robotic DaVinci System (Intuitive Surgical Inc, Mountain View, CA). The Computer Motion System (Computer Motion, Santa Barbara, CA) includes the Aesop 3000, a voice-controlled endoscope positioning robot, the Hermes Control Center, a centralized system designed to voice control a series of networked "smart" medical devices, and the Zeus robotic surgical system. Much of this technology evolved from early military efforts to develop robotic medics for the battlefield. Bringing technology from the battlefield to the pediatric cardiac operating room will require profound technological improvements. The range of motion of the mechanical arms and the large port sizes for endoscopes and instruments used in available systems now preclude safe use in small children. Peripheral cardiopulmonary bypass is used in most robotic techniques, creating unnecessary femoral vascular trauma in pediatric patients. Personal experience with
available robotic instrumentation makes it clear that the complete absence of tactile feedback and the noticeable lag between activating the controller and instrument response makes precise, gentle tissue manipulation very difficult. Three-dimensional imaging systems with high-resolution highquality images are not available, and existing systems with marginal optical quality require a ten-mm endoscope, which is prohibitively large for most pediatric cardiac applications. Congenital applications (eg, robotic closure of atrial septal defect) have been described anecdotally, however, a Medline reference to confirm this could not be found.
Conclusion Justification for the additional bypass time needed to perform routine cardioscopy during open-heart surgery consists of the same arguments used to support the use of intraoperative transesophageal echocardiography.2o Cardioscopy allows the entire cardiac team to visualize even remote cardiac anatomy before repair. It allows interventional cardiologists to perform hybrid procedures with cardiac surgeons. It allows visualization of delicate structures during repairs and may improve operative precision. It allows confirmation of complete repair before coming off bypass, so that additional repairs may be performed without delay. It provides a visual database for each patient's operation that can be used to correlate with other imaging modalities, and communicate with parents, colleagues, and students. Ultimately, these images may allow us to identify errors in technique or variants in anatomy (eg, in patients undergoing valve repair or subaortic resection), which have resulted in recurrent lesions, which to date have not been explainable in most patients. Naval commanders use periscopes, astronomers use telescopes, proctologists use, well, you get the picture, and congenital heart surgeons should be-
VIdeo-Assisted Cardioscopy
come comfortable using enhanced visualization with video-assisted cardioscopy.
References J. Burke RP, Michielon G, Wernovsky G: Video-assisted cardioscopy in congenital heart operations. Ann Thorac Surg 58: 864-868, 1994 2. Miyaji K, Hannan RL, Ojito J, et al: Video-assisted cardioscopy for intraventricular repair in congenital heart disease. Ann Thorac Surg 70:730-737, 2000 3. Reuthebuch 0, Roth M, Skwara W, et al: Cardioscopy: Potential applications and benefit in cardiac surgery. Eur J Cardiothorac Surg 15:824-829, 1999 4. Bauer EP, Reuthebuch OT, Roth M, et al: Diagnostic trans aortic cardioscopy of the left ventricle. Ann Thorac Surg 62: 1845-1846, 1996 5. Bauer EP, Reuthebuch OT, Roth M, et al: Video-assisted resection of hypertrophied and fibrous intraventricular tissue. Ann Thorac Surg 63:1180-1182,1997 6. Melero JM, Rodriguez I, Such M, et al: Left ventricular outflow tract obstruction with mitral mechanical prosthesis. Ann Thorac Surg 68:255-257, 1999 7. Greco E, Mestres CA, Cartana R, et al: Video-assisted cardioscopy for removal of primary left ventricular myxoma. Eur J Cardiothorac Surg 16:677-678, 1999 8. Mazza IL, Jacobs JP, Aldousany A, et al: Video-assisted cardioscopy for left ventricular thrombectomy in a child. Ann Thorac Surg 66:248-250, 1998 9. Rao V, Freedom RM, Black MD: Minimally invasive surgery with cardioscopy for congenital heart defects. Ann Thorac Surg 68:1742-1745,1999 10. Uchida Y, Tomaru T, Nakamura F, et al: Percutaneous fiberoptic cardioscopy of the left ventricle. Jpn Heart J 32:455471, 1991 II. Legget ME, Shaw DP: Fiberoptic cardioscopy under cardiopulmonary bypass:
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potential for cardioscopic surgery? Ann Thorac Surg 58:222-225, 1994 12. Inoue Y, Yozu R, Mitsumaru A, et al: Feasibility study of vascular-endoscopic valvuloplasty. Using a laser and flexible endoscope. ASAIO J 40:M811-M815, 1994 13. Inoue Y, Yozu R, Mitsumaru A, el. al: Video assisted thoracoscopic and cardioscopic radiofrequency Maze ablation. ASAIO J 43:334-337, 1997 14. Seward JB, Packer DL, Chan RC, et al: Ultrasound cardioscopy: Embarking on a new journey. Mayo Clin Proc 71 :629-635, 1996 15. Yamamoto N, Hirao K, Toshida N, et al: Nonfluoroscopic guidance for catheter placement into the coronary sinus under direct vision using a balloon-tipped cardioscope. Pacing Clin Electrophysiol 21: 1724-1729, 1998 16. Kohl T, Szabo Z, Suda K, et al: Fetoscopic and open transumbilical fetal cardiac catheterization in sheep. Potential approaches for human fetal cardiac in tervention. Circulation 95: 1048-1053, 1997 17. Loulmet D, Carpentier A, d'Attellis N, et al: Endoscopic coronary artery bypass grafting with the aid of robotic assisted instruments. J Thorac Cardiovase Surg 118:4-10, 1999 18. Kappert U, Cichon R, Schneider J, et al: Closed chest bilateral mammary artery grafting in double-vessel coronary artery disease . Ann Thorac Surg 70: 1699-170 I, 2000 19. Chitwood WR, Nifong LW, Elbeery JE, et al: Robotic mitral valve repair: Trapezoidal resection and prosthetic annuloplasty with the Da Vinci surgical system. J Thorac Cardiovasc Surg 120: 11711172, 2000 20. Bengur AR, Li jS, Herlong JR, et al: Intraoperative transesophageal echocardiography in congenital heart disease. Semin Thorae Cardiovasc Surg 10:255264, 1998
Key words: Cardioscopy, minimally invasive surgery, video-assisted thoracoscopic surgery, endoscopy, interventional catheterization, congenital heart surgery, intraoperative stents.
may be defined as the use of C ardioscopy endoscopic imaging during open-heart
procedures to enhance the visualization and repair of remote intracardiac structures. Experience with video-assisted thoracoscopic techniques for extracardiac lesions, such as patent ductus arteriosus ligation, intuitively led investigators to begin using direct videoassisted cardioscopy during open-heart repairs. 1 Video-assisted cardioscopy allows surgeons to achieve anatomic visualization without resorting to excessive retraction or extended cardiac incisions. Cardioscopy provides the entire operative team with an image of the defect and allows immediate assessment of the efficacy of repair. Additionally, video-assisted endoscopic imaging has proven to be advantageous during minimally invasive procedures by enhancing visualization in the operative field when operating through small incisions. Cardioscopy also has formed a platform for combined or hybrid procedures using both transcatheter From the Division of CardIOvascular Surgery, };fzaml Children's Hospital, Miami, FL. Address rtprint requests to Redmond P. Burke, MD, Division of Cardiovascular Surgery, Miami Chlldrtn's Hospital, 3200 SW 60 Court, Suite 102, Mzami, FL 33155-4069. Copyright © 2001 by WB. Saunders Company 1092-9126101/0401-0018135.0010 doi: 10.JO.53Ipcsu.2001.246.52
208
techniques and minimally invasive surgery. We anticipate that an expanding array of new procedures will emerge in the coming years, guided by various forms of video-assisted cardioscopy.
Technique Intraoperative cardioscopy is performed with the same endoscopic video-assisted equipment used for extracardiac repairs. Cardioscopy was initially used selectively, when difficult exposure was anticipated. However, the need for remote visualization during congenital heart repair is unpredictable, so we now use the technique routinely during every operation. The cardioscope has become a common eye for the cardiac team, allowing everyone in the cardiac operating room to see into the cardiac chambers. Routine use has allowed the scrub technicians to become comfortable with the equipment, and to create a consistent practice plan for cardioscopy and image acquisition. By enabling the cardiac team to see the operation in progress, team members are able to anticipate necessary actions, which has increased operative efficiency. A mechanical arm can be used to stabilize the camera in the operative field and free the surgeon's hands. \Ve now position the endoscope at the foot of the pa-
Pediatric Cardiac Surgery Annual ojthe Seminars
In
Thoracic and Cardiovascular Surgery, Vol 4, 2001: pp 208-215
Video-Assisted CardioJcop)'
209
Figure 1. Ope rative setup for intraoperative cardioscopy. tient's bed, in the operative field, where it can be rapidly passed to the surgeon like any other instrument (Fig I) . The cardioscope path into the operative field is determined by the patient's anatomy. A variety of approaches (aortic, pulmona ry, right atrial, left atrial, and through septal defects) are possibl e. Every cardiac chambe r and great vessel , the pulmonary veins and all valves can be exposed with the cardioscope. The pleural spaces also can be explored through partial or full sternotomy. Our experience with cardioscopy has enabl ed us to develop a protocol for documenting cardiac operatio ns and managing ope rative images . W e routinely begin ope n-h e art procedures by capturing images of any important external cardiac a natomy with th e endoscope . We th e n commence exposur e of th e cardiac defect, with or without cardiopulmonary bypass, and again document th e anatomy with the
cardioscope, looking for un expected anatomic variants or potential problems, planning suture lines, and sizing baffles and patches. The cardiac repair is peI"furmed, with intermittent cardioscopic assistance to e nsure precision. Once th e defects have b ee n repaired, compl e tion images are obt a ined, and thc ope ration s are completed. In minimally invasive repairs, rul e rs arc placed on the incision s to document incision length. From the series of intraoperative images coll ected during each ope ration, luur images are selected by the surgeon to show the cardiac anatomy before and after repair. Foul' print copies an~ made , Ollt' for the patient and famil y, one fur the re ferring physician, one for the patient's ch a rt , and one for the \\-'ee kly morbidity a nd mort ality conference . At this conference all intraoperatiVl' imag-cs are revi ewed and correl a ted with pre operati\'e imaging techniques (eg, echocardiogra-
210
Redmond P. Burke
phy, magnetic resonance images, angiograms) and postoperative events.
Clinical Applications We recently summarized our experience with routine cardioscopy for congenital heart repair.2 From 1995 to 1999, we used intraoperative cardioscopy in 409 consecutive patientsundergoing open-heart repairs. Cardiascopy was used to facilitate and document the repair of the following lesions: ventricular septal defects (VSD), tetralogy of Fallot, double outlet right ventricle, atrioventricular canal, subaortic stenosis, valve repair, Rastelli and Rev procedures, Konno and Ross-Konno operations, and a variety of other complex repairs. Cardioscopy provided excellent visualization in each case without significantly prolonging operative times. Intraoperative images were collected for the cardiac surgery database, documenting each child's anatomy before and after repair. Surgery through small incisions was facilitated. Operative mortality was 1.2% and no patients required reoperations before discharge. There were no complications related to cardioscopy. At a mean follow-up of 22 months, there was a 1.2% incidence of reoperations for residual or recurrent lesions. We concluded that routine use of the technique was feasible and potentially useful. Other investigators have described similar experiences with routine intraoperative cardioscopy. Reuthebuch et aI3 describes an experience in 100 patients, using a 5 mm flexible or rigid cardioscope to visualize a wide variety of cardiac lesions, and reported no complications related to the technique. Cardioscopy is particularly useful for VSD repair. Reliance on transesophageal echocardiography to ensure complete closure necessitates going back on bypass and reopening the heart when residual defects are detected. Cardioscopy may show residual defects before atrial closure, allowing immediate repair. For perimembranous defects, the scope is advanced through the right atrium and the
tricuspid valve immediately after cardiac arrest is initiated. A determination is made as to the need for detaching the anterior leaflet of the tricuspid valve to improve exposure. A pericardial patch is placed with running suture, and any concern about proximity to the aortic valve leaflet, the conduction system, or any muscle folds that might produce a residual defect can be seen with the cardioscope. Muscular defects can be exposed endoscopically, and direct or device closure can be guided. We reported our experience with 150 VSDs of all types in patients weighing from 2.3 kg to 76.8 kg.2 Follow-up echocardiography by both transesophageal echocardiography and postoperative transthoracic echocardiography showed small residual VSDs in only 12 patients (seven of these had multiple defects preoperatively), and no patients required reoperation. There was no control experience without cardioscopy to allow us to conclude that cardioscopy reduced the incidence of residual defects after VSD repair. We also have been pleased with the utility of cardioscopy for valve procedures. We described 50 patients undergoing valve repairs as part of their congenital heart procedures. 2 These patients ranged in weight from 3.5 kg to 80 kg (mean, 21.2 kg). Before and after repair, valve competence was tested by saline infusion, after removing atrial retractors, to create a more normal approximation of valvar anatomic relationships. One patient was found to have severe left-sided atrioventricular valve insufficiency after complete atrioventricular canal repair and underwent valve replacement. At a mean follow-up of 22 months, no patients required reoperation for valvar pathology. Figure 2 shows the intra· operative images of a left-sided atrioventricular valve in a patient who had undergone atrioventricular canal repair as an infant and subsequently presented to us with valvar insufficiency. The second image in Fig 2 shows the valve immediately after repair, which was effective. Numerous creative clinical applications of intraoperative cardioscopy have now been re-
Video-Assisted Cardioscopy
ported. Bauer et al 4 used transaortic cardioscopy to explore the left ventricle, thereby avoiding the need for ventriculotomy. In a subsequent report, Bauer et al'> used cardioscopy to facilitate resection of hypertrophic left ventricular myocardium. Cardioscopy also has been used to diagnose and treat left ventricular outflow tract obstruction related to a mitral valve prosthesis.!) Greco et al 7 recently excised a left ventricular myxoma using transaortic video-assisted cardioscopy. We reported resection of a left ventricular thrombus in a 17-year-old girl with viral myocarditis and cardiomyopathy.s
Cardioscopy in Minimally Invasive Surgery Several investigators have described using cardioscopy as an adjunct to surgery through limited incisions. Rao et al 9 described using cardioscopy to facilitate atrial septal defect repairs through partial lower sternotomy. Cardioscopy addresses one of the crucial limitations inherent in these procedures - compromised visua1ization. We have found this particularly true for subaortic membrane resection, in which cardioscopy allows magnification of the left ventricular outflow tract from the aortic incision down to the ventricular apex. At Miami Children's Hospital, we approach this lesion using a 4-cm partial upper sternotomy and a combination of endoscopic guidance and direct vision. Beginning in March 1997, 15 patients with subaortic stenosis, ranging in age from 2 to 16 years (mean, 6.7 years) and in weight from 12.0 kg to 65.0 kg (mean, 26.0 ::!: 13.8 kg), underwent repair. There were 10 boys and five girls. All patients were diagnosed with subaortic fibromembranous stenosis by eehocardiography. Four patients had mild aortic regurgitation. Their preoperative systolic pressure gradient between left ventricle and aorta measured by echocardiography ranged from 25 to 125 mmHg (mean, 55.1 ::!: 22.S mmHg). Incisions ranged from 4.0 em to 9.0 cm (mean, 5.3 ::!: 1.6 cm). Mean operation time (defined as the
211
time from skin incision to wound dressing) was 153.7 ::!: 36.2 minutes (range, 115 to 225 minutes). Mean cardiopulmonary bypass and cross clamp times were 68.0 ::!: 15.9 minutes (range, 50 to 113 minutes) and 42.1 ::!: 14.8 minutes (range, 20 to 77 minutes), respectively. Mean postoperative systolic pressure gradient between left ventricle and aorta measured by echocardiography was 6.1 mmHg and there was no pressure gradient in 11 patients (73%). Twelve patients (80%) were extubated in the operating room. There were no hospital deaths and no postoperative complications. The duration of hospital stay was 3.1 ::!: 1.4 days (range, 2 to 7 days). Mean patient follow-up is 15.3 months, ranging from 2.1 months to 27.1 months, and we have seen no deaths or reoperations. Cardioscopy does have technical limitations; condensation or blood can cloud the lens, the equipment requires sophisticated maintenance to maintain a high quality image, bypass and arrest time is consumed, and even the best image lacks depth perception. With training, the operating team can become facile with the endoscopic equipment, and our mechanical failure rate in the operating room for image acquisition has been zero. Endoscopy does provide increased magnification over conventional surgical lou pes, up to four times normal, and the ability to use angled or flexible fiberoptic scopes enable the team to look around corners and into deep recesses and vessels within the heart.
Experimental Applications A variety of laboratory applications for direct endoscopic and remote fiberoptic cardioscopy have been described. In 1991 , Uchida et altO described transcatheter fiberoptic endoscopy to obtain direct video images of the beating endocardium. In 1994, Legget and Shawl I suggested a technique for fiberoptic cardioscopy. This technique was limited by difficulties with flushing the heart with clear
212
Redmond P. Burke
Figure 2. (Left) A cardioscopic image of a badly deformed and insufficient left-sided atrioventricular valve in a 2-year-old child. (Right) A postrepair image of the valve showing competence with saline infusion.
sten\
Left Pulmonary Artery
Cardioscope Balloon Catheter
Figure 3. Intraoperative pulmonary artery stenting with cardioscopic guidance.
Video-Assisted Cardioscopy
fluid to allow visualization, but suggested the possibility of percutaneous endoscopically guided heart repairs. Inoue et al 12 described fiberoptic endoscopy for laser valvuloplasty in an animal model, although there were problems with maintaining position within the beating heart. More recently, Inoue et al 13 described the potential usefulness of a combination of transthoracic radiofrequency catheter ablation with video-assisted thoracoscopic and cardioscopic linear ablation of atrial fibrillation pathways. The technique was presented as a possible future off pump alternative to the Maze procedure. Seward et aP+ described a device for ultrasound cardioscopy with balloon displacement of intracardiac blood as a promising means of performing precise under-blood diagnostic and therapeutic maneuvers in an animal study of catheter ablation. Yamamoto et aps also described using a balloon-tipped cardioscope, in their investigation, to visualize the right atrial posterior septum and guide an electrode catheter into the coronary sinus in dogs. Kohl et al 16 describes remarkable work with fetal sheep to assess the feasibility of fetoscopic and open transumbilical fetal cardiac catheterization, guided by fetal transesophageal echocardiography, to provide alternative approaches for human fetal cardiac intervention.
Hybrid Procedures: Combining Cardioscopy and Transcatheter Intervention Interventional cardiologists were initially chagrined that cardioscopy was very efTective at documenting technical failures in the catheterization laboratory, such as stent migrations and septal device misplacements, but this concern has largely subsided. There is now significant interest in developing hybrid techniques combining transcatheter techniques with intraoperative cardioscopy. Transcatheter endovascular stent implantation is an effective modality for treating branch pulmonary artery stenoses. However,
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a subgroup of patients with branch pulmonary artery may benefit from direct intraoperative placement of these prostheses. Intraoperative stent placement may be limited by poor visualization of the target lesion and the relationship between the distal stent and pulmonary artery side branches. Visualization may be particularly difficult when the stent must be placed behind the aorta or distally in the branch pulmonary artery. We hypothesized that video-assisted cardioscopic guidance of stent placement would improve visualization and increase the accuracy of stent positioning and deployment in the operating room. We prospectively collected and analyzed data on 11 consecutive children undergoing intraoperative branch pulmonary artery stent implantation with video-assisted cardioscopic guidance. Success was defined as complete relief of stenosis as well as avoidance of occlusion of any major secondary pulmonary artery branches. The technique is demonstrated in Fig 3. All patients were on cardiopulmonary bypass at the time of videoassisted cardioscopic guidance. Fourteen stents were implanted in 11 patients with a success rate of 93% (13/14). Mean age and weight were 53.7 months (range, 16 days to 150 months) and 14.1 kg (range, 2.1 to 31.5 kg). Ten of the 11 patients (91 %) were reoperations. Stents were placed during associated surgery in seven patients because of failed percutaneous stent placement in two and for inability to wean from cardiopulmonary bypass in two. Diagnoses included pulmonary atresia with VSD in nine patients, and one each with truncus arteriosus and tetralogy of Fallot with discontinuous left pulmonary artery. The single stent placement failure was secondary to interference from a previously placed stent, which required surgical removal and patching. Early follow-up (mean, 15 months) showed one death secondary to sepsis. There were no late complications or reinterventions required. Our preliminary conclusion is that cardioscopic guidance of intraoperative stent
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placement is straightforward and offers valuable visual assistance during intraoperative stent placement. Cardioscopy also has been used to reposition septal occlusion devices placed in the catheterization laboratory, I and could be used for elective intraoperative device placement during complex multilesion repairs.
Robotic Video-Assisted Surgery Converging advances in technique and technology may allow robotic endoscopic open heart procedures to be performed, however, there are daunting technological challenges to address. Because of size constraints, clinical applications of robotic heart surgery have been limited to adult patients. Coronary artery bypass,17 internal mammary artery harvest, 18 and mitral valve repair,19 have been described in human applications. Several companies are building their conception of the futuristic operating rooms based on robotic surgery. These include "The Intuitive Surgical System," which consists of the robotic DaVinci System (Intuitive Surgical Inc, Mountain View, CA). The Computer Motion System (Computer Motion, Santa Barbara, CA) includes the Aesop 3000, a voice-controlled endoscope positioning robot, the Hermes Control Center, a centralized system designed to voice control a series of networked "smart" medical devices, and the Zeus robotic surgical system. Much of this technology evolved from early military efforts to develop robotic medics for the battlefield. Bringing technology from the battlefield to the pediatric cardiac operating room will require profound technological improvements. The range of motion of the mechanical arms and the large port sizes for endoscopes and instruments used in available systems now preclude safe use in small children. Peripheral cardiopulmonary bypass is used in most robotic techniques, creating unnecessary femoral vascular trauma in pediatric patients. Personal experience with
available robotic instrumentation makes it clear that the complete absence of tactile feedback and the noticeable lag between activating the controller and instrument response makes precise, gentle tissue manipulation very difficult. Three-dimensional imaging systems with high-resolution highquality images are not available, and existing systems with marginal optical quality require a ten-mm endoscope, which is prohibitively large for most pediatric cardiac applications. Congenital applications (eg, robotic closure of atrial septal defect) have been described anecdotally, however, a Medline reference to confirm this could not be found.
Conclusion Justification for the additional bypass time needed to perform routine cardioscopy during open-heart surgery consists of the same arguments used to support the use of intraoperative transesophageal echocardiography.2o Cardioscopy allows the entire cardiac team to visualize even remote cardiac anatomy before repair. It allows interventional cardiologists to perform hybrid procedures with cardiac surgeons. It allows visualization of delicate structures during repairs and may improve operative precision. It allows confirmation of complete repair before coming off bypass, so that additional repairs may be performed without delay. It provides a visual database for each patient's operation that can be used to correlate with other imaging modalities, and communicate with parents, colleagues, and students. Ultimately, these images may allow us to identify errors in technique or variants in anatomy (eg, in patients undergoing valve repair or subaortic resection), which have resulted in recurrent lesions, which to date have not been explainable in most patients. Naval commanders use periscopes, astronomers use telescopes, proctologists use, well, you get the picture, and congenital heart surgeons should be-
VIdeo-Assisted Cardioscopy
come comfortable using enhanced visualization with video-assisted cardioscopy.
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potential for cardioscopic surgery? Ann Thorac Surg 58:222-225, 1994 12. Inoue Y, Yozu R, Mitsumaru A, et al: Feasibility study of vascular-endoscopic valvuloplasty. Using a laser and flexible endoscope. ASAIO J 40:M811-M815, 1994 13. Inoue Y, Yozu R, Mitsumaru A, el. al: Video assisted thoracoscopic and cardioscopic radiofrequency Maze ablation. ASAIO J 43:334-337, 1997 14. Seward JB, Packer DL, Chan RC, et al: Ultrasound cardioscopy: Embarking on a new journey. Mayo Clin Proc 71 :629-635, 1996 15. Yamamoto N, Hirao K, Toshida N, et al: Nonfluoroscopic guidance for catheter placement into the coronary sinus under direct vision using a balloon-tipped cardioscope. Pacing Clin Electrophysiol 21: 1724-1729, 1998 16. Kohl T, Szabo Z, Suda K, et al: Fetoscopic and open transumbilical fetal cardiac catheterization in sheep. Potential approaches for human fetal cardiac in tervention. Circulation 95: 1048-1053, 1997 17. Loulmet D, Carpentier A, d'Attellis N, et al: Endoscopic coronary artery bypass grafting with the aid of robotic assisted instruments. J Thorac Cardiovase Surg 118:4-10, 1999 18. Kappert U, Cichon R, Schneider J, et al: Closed chest bilateral mammary artery grafting in double-vessel coronary artery disease . Ann Thorac Surg 70: 1699-170 I, 2000 19. Chitwood WR, Nifong LW, Elbeery JE, et al: Robotic mitral valve repair: Trapezoidal resection and prosthetic annuloplasty with the Da Vinci surgical system. J Thorac Cardiovasc Surg 120: 11711172, 2000 20. Bengur AR, Li jS, Herlong JR, et al: Intraoperative transesophageal echocardiography in congenital heart disease. Semin Thorae Cardiovasc Surg 10:255264, 1998