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Ann Thorac Surg 1999;68:1742-1745
© 1999 The Society of Thoracic Surgeons

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Original Articles

Minimally invasive surgery with cardioscopy for congenital heart defects

^a Division of Cardiology, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
^b Division of Cardiovascular Surgery, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada

Address reprint requests to Dr Black, Department of Cardiac Surgery, Lucile Packard Children’s Hospital, Stanford University School of Medicine, Stanford, CA 94305-5407
e-mail: michael.black{at}stanford.edu

	Abstract

Top Abstract Introduction Patients and methods Results Comment References

 
Background. Minimally invasive cardiac surgery remains a burgeoning discipline lacking adequate instrumentation and perfusion circuitry, particularly for the pediatric population. Cardioscopy, utilizing first generation imaging equipment with a variety of different angled lenses, provides a unique opportunity to expand the realm for the diagnosis and treatment of congenital heart disease.

Methods. Sixty-eight children with a mean weight of 23 ± 11 kg (range 8–62 kg) who underwent repair of atrial septal defects (ASD) using a minimally invasive approach (MINI group) were compared to 25 consecutive children undergoing ASD repair via a full median sternotomy (CONT group). In addition, mini-sternotomy with or without cardioscopy allowed for the diagnosis and treatment of more complex congenital lesions in 24 children.

Results. The mean age in the MINI group was 7 ± 3 years (range 1–15 years) compared to 4 ± 4 years in the CONT group (p = 0.009). The mean body surface area of the MINI group (0.8 ± 0.2 m²; range 0.4–1.6 m²) was larger than the CONT group (mean 0.6 ± 0.3 m²; range 0.2–1.6 m²; p = 0.04). Ischemic times and cardiopulmonary bypass times were similar in both groups. Postoperative hospital stay was shorter in the MINI group (3 ± 2 versus 4 ± 1 days; p = 0.014).

Conclusions. Minimally invasive cardiac surgery can be performed safely even in small children with congenital heart defects. In addition to improved cosmetic results, these techniques can reduce the utilization of hospital resources. Future advances in cardioscopic technology should permit minimally invasive repair of most complex congenital heart lesions and should obviate the need for full sternotomy in the majority of children undergoing cardiac surgery.

	Introduction

Top Abstract Introduction Patients and methods Results Comment References

 
Minimally invasive techniques of surgery have been employed for a wide variety of cardiothoracic procedures. Unfortunately, there remains a lack of adequate instrumentation and perfusion circuitry, particularly for the pediatric population. Intracardiac imaging using cardioscopy is a novel method to improve visualization during minimally invasive surgery. We have employed cardioscopy to aid in the diagnosis and repair of several congenital heart defects over the past 3 years. We presently employ a variety of angled lenses ranging from 0 to 30 degrees with a diameter of 2.6 to 5 mm. We believe that further advances in surgical technology, particularly with respect to surgical instrumentation and imaging equipment, will lead to an expanded role for minimally invasive operation for the treatment of congenital heart disease.

In this report, we compare the in-hospital results of atrial septal defects (ASD) repair using a conventional full median sternotomy approach with a minimally invasive approach employing a small skin incision (4–5.5 cm) and partial sternotomy. In addition, we describe the use of cardioscopy to aid in the diagnosis and repair of more complex congenital heart defects.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment References

 
Between July 1, 1996 and September 1, 1998, 93 children underwent surgical repair of isolated atrial septal defects (with or without ligation of a patent ductus arteriosus) by one surgeon (MDB). The first 25 consecutive patients underwent repair utilizing a full median sternotomy and represent the control group (CONT). The remaining 68 children underwent repair via a limited skin incision and partial sternotomy (MINI group). In addition, 24 children underwent surgical repair of more complex congenital heart defects utilizing a minimally invasive approach augmented with cardioscopic imaging.

Operative technique
Techniques of anesthetic induction and maintenance were identical in all patients. In the CONT group, a midline incision was created extending from the inferior aspect of the sternal notch to the xiphoid process. The heart and great vessels were then exposed via a full median sternotomy. In the MINI group, a midline incision ranging from 4 to 5.5 cm, depending on the size of the child, was created extending over the lower two-thirds of the sternum. A limited skin flap was developed circumferentially to avoid cutaneous tears during the operative procedure and to enhance exposure. A partial sternotomy was then performed extending from the xiphoid process to the level of the third intercostal space. The manubrium was preserved in all patients in the MINI group [1].

Cardiopulmonary bypass was then initiated using standard ascending aortic and bicaval venous cannulation. The sizes of the caval and aortic cannulae were similar in both groups. Epicardial clips (or a fibrillation pad) were then placed on the anterior and diaphragmatic surfaces of the right ventricle (or in the posterior pericardium) to facilitate induction of fibrillatory arrest. After successful fibrillation, caval snares were placed around both venous cannulae and the patient’s temperature allowed to drift 34°C. Alternatively, 2:1 blood cardioplegia was delivered via an ascending aortic cannula and the aorta cross-clamped to achieve cardiac arrest.

A right atriotomy was made obliquely towards the inferior vena cava (IVC). Hand-held retractors were then placed into the right atrium to expose the defect. Atrial septal defects with extension into the inferior vena cava were repaired after removal of the IVC cannula with venous return via sucker bypass. Defects were repaired either primarily or with an autologous pericardial patch as indicated.

After routine deairing of the left heart, fibrillation was discontinued and the child weaned off cardiopulmonary bypass. Sternal closure was similar in both groups and consisted of three or four interrupted stainless steel wires and absorbable sutures for the subcutaneous tissue and skin. A single mediastinal chest drain was left in situ in all patients.

For children with more complex congenital heart defects, which were thought to be amenable to minimally invasive repair, a rigid cardioscope (Storz Instruments, St. Louis, MO) was inserted into the operative field to improve visualization of the cardiac chambers. The choice of a specific angled lens was in part determined by the presenting morphology. For example, 30-degree angled lenses permit excellent visualization of the left atrioventricular valve via the right atrium.

Postoperative care was uniform in all patients. Children were extubated and transferred from the intensive care unit to the general ward according to standard criteria ("fast-tracked" in 4 hours) applied by the attending cardiac intensivist and an arranged cardiac care plan. All patients received intravenous morphine sulfate as an initial analgesic and were then weaned to oral codeine and ibuprofen as tolerated.

Statistical methods
Statistical analysis was performed using the SAS software program (SAS Institute, Cary, NC). Continuous data were analyzed using Student’s t test and are expressed as mean ± standard deviation. Categorical data were analyzed using ² or Fisher’s exact test as appropriate. Exact p values are provided for each comparison.

	Results

Top Abstract Introduction Patients and methods Results Comment References

 
Table 1 illustrates the demographic data for both groups. Children in the MINI group tended to be older and heavier with larger body surface areas. There were 5 infants (age less than 1 year) in the CONTROL group compared to only 1 in the MINI group (p = 0.005 by Fisher’s exact test). The location of the atrial septal defect was similar in both groups.

View larger version (104K): [in this window] [in a new window]   Fig 1. Representative skin incision from a child in the MINI group. The incision is extended subcutaneously over the sternum and a hemi-sternotomy performed to the level of the manubrium.

View larger version (22K): [in this window] [in a new window]   Fig 2. Postoperative length of stay was significantly shorter (p = 0.014) in the MINI group. (LOS = length of stay in days.)

View larger version (99K): [in this window] [in a new window]   Fig 3. Representative view through a 5-mm cardioscope illustrating a cleft in the left atrioventricular valve. Excellent visualization of the anatomic defect facilitated repair via a minimally invasive approach. Note the single large papillary muscle ("parachute" mitral valve) with absence of subvalvular apparatus to the region of the cleft.

	Comment

Top Abstract Introduction Patients and methods Results Comment References

 
Surgical closure of atrial septal defects is now associated with minimal morbidity and mortality in the elective setting. Therefore, introduction of a minimally invasive approach to the correction of this lesion must be proven to be as safe and as effective as a traditional median sternotomy. However, even if no objective advantage exists (apart from cosmesis and parental/patient satisfaction), the experience gained by utilizing a minimally invasive approach to ASD closure may allow for the correction of more complex congenital heart disease.

Several authors have reported their clinical experience with alternative surgical approaches to the right heart [1–8]. These include a transxiphoid approach [2], an anterolateral thoracotomy [6, 7], and a mini-sternotomy [1, 3]. Each author provides arguments for the superiority of their individual approach. Our initial goal was to gain experience with cannulation and intracardiac repair of simple lesions in order to expand our indication for minimally invasive surgery. We feel that a mini-sternotomy approach provides excellent access to all cardiac chambers, especially when appropriately augmented with cardioscopy [9]. A modification of our technique, which involves sternotomy of the manubrium and proximal sternum, allows for full access to the great vessels.

It is our belief that minimizing surgical trauma may be of more benefit to higher risk children who would then require less narcotic analgesia in the postoperative period. Since respiratory complications are a significant cause of prolonged intensive care unit and hospital stay, avoidance of narcotic analgesia should improve the clinical outcomes in patients undergoing minimally invasive cardiac surgery.

In this study which describes our initial experience with mini-sternotomy, we found a significant reduction in postoperative hospital stay. Despite a higher number of associated procedures such as mitral valvuloplasty, the ischemic times and extracorporeal perfusion times were similar between groups. Although ischemic times were statistically longer in the MINI group (28 versus 22 minutes; p = 0.03), we do not feel this difference to be of clinical significance. In addition, these figures represent a learning curve with minimally invasive incisions among the different housestaff that are eager to learn the technique. With additional experience, we expect that ischemic times will be similar to a traditional full sternotomy approach, even with more complex intracardiac repairs.

Our experience with ASD repair enabled us to perform more complicated repairs utilizing a mini-sternotomy. Table 3 illustrates the range of procedures that have been successfully performed using a minimally invasive approach. Several of these procedures involved the use of intracardiac imaging with cardioscopy. We have found this tool to be extremely valuable for improving visualization in both mini- and full sternotomy incisions. In addition, the cardioscope is a useful educational tool as it allows the resident to perform an operation under direct supervision of the attending surgeon at all times. The most striking example is that of mitral valve repair. Exposure of the mitral valve is often very difficult and, even with excellent exposure, it is nearly impossible for the attending surgeon to supervise every manipulation of the valve. Cardioscopy allows the entire operating room to observe valvular pathology, the placement of sutures, and the coaptation of valve leaflets after repair. Figure 3 is a representative example of the excellent intracardiac visualization provided by the cardioscope.

In summary, this study demonstrates that ASD repair via a mini-sternotomy is a safe and reproducible operation when compared with a traditional full sternotomy approach. In addition, we found postoperative length of stay to be shorter in the MINI group, likely as a result of lower narcotic requirements and earlier mobilization. The introduction of intracardiac imaging permitted repair of more complex congenital lesions via a mini-sternotomy incision and may prove invaluable for all surgical incisions both as an aid to surgical visualization and as a teaching tool. As experience accumulates, and as instrumentation and imaging technology improves, it will be possible to repair most forms of congenital heart disease utilizing a minimally invasive approach.

	References

Top Abstract Introduction Patients and methods Results Comment References

 

1. Black M.D., Freedom R.M. Minimally invasive repair of atrial septal defects. Ann Thorac Surg 1998;65:765-767.[Abstract/Free Full Text]
2. Barbero-Marcial M., Tanamati C., Jatene M.B., Atik E., Jatene E.D. Transxiphoid approach without median sternotomy for the repair of atrial septal defects. Ann Thorac Surg 1998;65:771-774.[Abstract/Free Full Text]
3. Gundry S.R., Shattuck O.H., Razzouk A.J., del Rio M.J., Sardari F.F., Bailey L.L. Facile minimally invasive cardiac surgery via ministernotomy. Ann Thorac Surg 1998;65:1100-1104.[Abstract/Free Full Text]
4. Peters W.S., Stevens J.H., Smith J.A., Rosenfeldt F.L., Siegel L.C., Burdon T.A. Minimally invasive right heart operations. Ann Thorac Surg 1997;64:1843-1845.[Abstract/Free Full Text]
5. Chang C.H., Lin P.J., Chu J.J., et al. Video-assisted cardiac surgery in closure of atrial septal defect. Ann Thorac Surg 1996;62:697-701.[Abstract/Free Full Text]
6. Massetti M., Babtasi G., Rossi A., et al. Operation for atrial septal defect through a right anterolateral thoracotomy. Ann Thorac Surg 1996;62:1100-1103.[Abstract/Free Full Text]
7. Grinda J.M., Folliguet T.A., Dervanian P., Mace L., Legault B., Neveux J.Y. Right anterolateral thoracotomy for repair of atrial septal defect. Ann Thorac Surg 1996;62:175-178.[Abstract/Free Full Text]
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