Eur J Cardiothorac Surg 1998;14:S122-S125
© 1998 Elsevier Science NL
Minimally invasive aortic valve replacement
Bruce L Fraziera,b,*,
Marvin J Derricka,b,
Sarj S Purewala,b,
Lawrence R Sowkaa,b,
Samir Johnac
a San Joaquin Community Hospital, 2615 Eye Street, Bakersfield, CA 93301, USA
b Bakersfield Memorial Hospital, 420 34th Street, Bakersfield, CA 93301, USA
c Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
* Corresponding author. 1711 28th Street, Bakersfield, CA 93301, USA. Tel.: +1 805 3278538; fax: +1 805 3275432.
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Abstract
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During a consecutive 12-month period from January 1996 to January 1997 inclusive, 108 aortic valve replacements were performed by one group of surgeons in two community hospitals The majority of the valve replacements were done in combination with other procedures or were redo surgeries. Thirty-one patients had primary isolated aortic valve replacement. Fourteen patients underwent aortic valve replacement via a standard sternotomy, and seventeen patients underwent aortic valve replacement using a minimally invasive parasternal approach, as described by Dr. Cosgrove. There were no operative deaths in either group; however there was one hospital death in each of the two groups. Blood loss and postoperative pain were less in the minimally invasive group. Although the cross-clamp times were longer in the minimally invasive group, with a mean of 82.7 min as compared with 63.1 min in the standard group, the length of stay was shortened, with a median of 5 days in the minimally invasive group as compared to 7 days in the sternotomy group. In the follow-up which ranges from 4–15 months, all patients in the minimally invasive group were New York Heart Class I or II. Patients with the parasternal incisions are permitted to return to work much earlier than those with a standard sternotomy incision. The decreased blood loss and postoperative pain, combined with the anticipated ease of re-entry via a median sternotomy in the future (should redo aortic valve replacement become necessary), make this approach our procedure of choice in isolated primary aortic valve replacement.
Key Words: Minimally invasive cardiac surgery • Aortic valve replacements • Sternotomy
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1. Introduction
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Like it or not, minimally invasive cardiac surgery is here to stay. Our colleagues in general, thoracic and orthopedic surgeons, have perfected and popularized minimally invasive approaches, but only recently has this approach been adapted for cardiac procedures. Minimally invasive coronary bypass surgery requires improved technology and re-training to become universally adapted. Aortic valve replacement, however, as initially described by Dr. Cosgrove of the Cleveland Clinic, requires no special instrumentation and only modest re-training.
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2. Materials and methods
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During a 1 year period from January 1996 to January 1997, 108 aortic valve replacements were performed by a single group of surgeons operating in two community hospitals. The majority of these operations were done in combination with other procedures including coronary bypass, mitral valve replacement, the Ross procedure, and redo valve replacement. Thirty-one patients had primary isolated aortic valve replacement. Fourteen of them underwent aortic valve replacement via a standard median sternotomy, and 17 patients had aortic valve replacement using the minimally invasive parasternal technique. One of these 17 patients was converted from a minimally invasive to a standard midline sternotomy early on in the series, and was excluded from the study. Patient selection was random and primarily determined by the interest of the authors. The only contraindications to the minimally invasive approach were severe chest wall deformities, redo surgery, or associated procedures.
In the sternotomy group there were five females and nine males ranging in age from 31–81, with an average age of 72.5 years. In the minimally invasive group there were five females and 12 males ranging in age from 61–88, with an average age of 62.5 years. The preoperative diagnosis in the sternotomy group was primarily aortic stenosis in 10, and aortic insufficiency in four, including one patient with bacterial endocarditis. In the minimally invasive group 14 patients had aortic stenosis and two patients had aortic insufficiency (Table 1
).
The valve type used was similar in both groups (Table 2
). Those with a standard sternotomy incision included six pericardial prostheses, two porcine, three St. Jude, and one Medtronic-Hall valve. In the minimally invasive group, eleven pericardial valves and five St. Jude valves were used.
The minimal invasive technique used was similar to that described by Dr. Cosgrove in 1996. Initially a double lumen endotracheal tube was routinely employed; however, we have found this was not necessary and now use single lumen endotracheal intubation. R2 rescue pads are used as well as a pacing Swan–Ganz catheter. A 10 cm right parasternal incision is made extending from the second costal cartilage to the fourth costal cartilage (Fig. 1
). This is a non-anatomic approach and the pectoralis muscle is divided. The right internal mammary artery and vein are ligated and divided, although this is probably not necessary in all cases. The third and fourth costal cartilages are resected sub-perichondrially, leaving a bed of perichondrium for subsequent closure. The right or left femoral artery is exposed through a 5 to 6 cm incision in the skin crease. The pericardium is exposed and incised longitudinally. Traction sutures are placed through the free edge of the pericardium and brought to the skin level. A self retaining retractor is placed (Fig. 2
). The patient is heparinized and the femoral artery cannulated. The right atrial appendage is cannulated with a standard two stage venous cannula and cardiopulmonary bypass is initiated. With the aorta decompressed an umbilical tape is placed around the ascending aorta. Following aortic crossclamping cold crystalloid cardioplegia is infused into the root of the aorta and moderate systemic hypothermia is instituted. The aorta is opened with an oblique incision and 4–0 silk retention sutures are placed to expose the valve. The aortic valve is then resected and a small caliber sump placed through the annulus into the left ventricle.
Additional cardioplegia is then delivered into the right and left coronary ostia. The prosthetic valve is then sutured in place, using interrupted technique. The aortotomy is closed with a double running suture of 3–0 Proline. The patient is rewarmed and placed in the Trendelenburg position. The cross-clamp is removed while the aortic root is vented. The majority of patients regain a sinus rhythm spontaneously, but several have required cardioversion. A single chest tube is then brought through a right lateral stab wound.
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3. Results
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A comparison of the two groups (Table 3
) demonstrates that the mean cross-clamp times were significantly longer in the minimally invasive group (P<0.0005) averaging 82.7 min, as compared to 63.1 min with the standard group. This is largely due to technical factors and interrupting the operation for the intra-coronary installation of cardioplegia versus the routine use of retrograde cardioplegia in the sternotomy group. Blood loss was lower in the minimally invasive group. Only three of 16 patients required a transfusion, as compared to seven of the 14 patients in the standard group. This achieved only marginal statistical significance, however P=0.77 using the Fisher-Exact test.
There was one hospital death in each group. A 73-year-old male had multiple admissions for congestive heart failure and died of multi-organ system failure on the 24th postoperative day following median sternotomy. The other patient was an 88-year-old female who underwent minimally invasive aortic valve replacement and died of respiratory and renal failure on the 20th postoperative day. The median length of stay for survivors was 5 days in the minimally invasive group versus 7 days for the sternotomy group. In the limited follow-up period of 4–15 months, all patients were New York Heart Class I or II.
Four patients in the minimally invasive group suffered minor complications. One patient had a mild wound infection that responded to antibiotic treatment. Two other patients had right upper lobe atelectasis that responded to respiratory toilet. The last patient had a transient AV block that required temporary pacing. On the other hand, two patients in the median sternotomy group suffered major complications. One patient had postoperative bleeding that required re-exploration. Another patient had dehiscence of the sternal wound, requiring rewiring. Two other patients developed pericardial effusions that required drainage.
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4. Discussion
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Modern success in cardiac surgery is based on cardiopulmonary bypass, myocardial protection, and median sternotomy [2]. Although median sternotomy provides excellent access to the heart and major vessels, it is associated with significant morbidity. Bleeding and pain related to traction of the ribs and thoracic ligaments has been well documented [1, 3]. The complication of greatest concern is a deep sternal wound infection which often requires debridement, followed by plastic surgical reconstruction, and can result in death. Minimal access aortic valve surgery offers an opportunity to decrease the morbidity associated with the midline approach. Although the surgical field is smaller, the exposure of the aortic valve is surprisingly good.
In this retrospective series, we have demonstrated that minimally invasive aortic valve surgery can be successfully performed in a variety of patients with isolated aortic valve disease. Mortality was similar in each group, however, major complications were significantly less in the minimally invasive patients. Although the cross-clamp times were longer in the minimally invasive group, the patients had a shorter postoperative length of stay and transfusion requirements were less.
In one patient early on in the series, the surgeon was uncomfortable with the exposure that was obtained and the incision was easily converted into a standard midline sternotomy. Dr. Cosgrove has described a method for doing this by incorporating the parasternal skin incision into the midline sternotomy incision. The minimally invasive approach for aortic valve surgery is obviously confined to patients with isolated aortic valve disease. Other contraindications to this approach include sternal deformities, as well as re-entry sternotomy.
Disadvantages of the right parasternal limited incision include poor access to the right superior pulmonary vein for venting, and also difficulty in placing a retrograde cardioplegia catheter for myocardial protection. In patients with aortic stenosis, a first dose of antegrade cardioplegia can be administered into the aorta immediately after cross-clamping. In patients with severe aortic insufficiency, myocardial protection must be totally dependent upon direct cannulation of the right and left coronary ostia after opening the aorta. In order to reduce the amount of blood in the operative field, we have passed a small sump catheter through the aortic annulus into the left ventricle. Another possibility to consider would be sumping the main pulmonary artery. At the conclusion of the operation the de-airing has to be done carefully since the apex of the heart is not accessible for venting. The risk of air embolism can be minimized by filling the heart cavities with blood and then rotating the table in different directions in addition to expanding the lungs prior to closure of the aortic suture line [4]. Adequate de-airing can be documented with a transesophageal echo. In our series of 16 patients who underwent minimally invasive aortic valve surgery, we had no neurologic complications.
We are encouraged by the early results of minimally invasive aortic valve replacement. These patients required less blood transfusions, were discharged sooner, and were able to return to normal activities of daily life earlier than their sternotomy cohorts. Clearly, the smaller incision is cosmetically more acceptable to patients. We expect that re-operation, if necessary, through a midline sternotomy should be easier to perform since the pericardium below the sternum remains intact protecting the heart from potential injury. There is a learning curve involved and the surgeon must develop a comfort level with operating through a small incision.
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References
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- Cosgrove DM, Sabik J. Minimally invasive approach for aortic valve operation. Ann Thorac Surg 1996;62:596-597.[Abstract/Free Full Text]
- Lyth BW. Minimally invasive cardiac surgery. J Thorac Cardiovasc Surg 1996;111:554-555.[Medline]
- Navia JL, Cosgrove DM. Minimally invasive mitral valve operations. Ann Thorac Surg 1996;62:1542-1544.[Abstract/Free Full Text]
- Tsai FC, Lin PJ, Chang CH, Liu HP, Tan PP, Lin FC, Chaing CW. Video-assisted cardiac surgery: a preliminary experience in re-operative mitral valve surgery. Chest 1996;110:1603-1607.[Abstract/Free Full Text]
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Abstract
1. Introduction
