Eur J Cardiothorac Surg 1999;16:S99-S102
© 1999 Elsevier Science NL
Evaluation of two new heart valve surgery techniques: partial sternotomy and port–access approaches
Kit V Arom*,
Robert W Emery,
Vibhu R Kshettry,
Karen A Dubois
Cardiac Surgical Associates, P.A., 920 East 28th Street, Suite 420, Minneapolis, MN 55407 USA
* Corresponding author. Tel.:+1-612-863-3982; fax: +1-612-863-3739.
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Abstract
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Objectives: This review attempts to compare the port–access and partial sternotomy approaches of minimally invasive valve surgery. Methods: Our brief experiences of the two techniques are summarized with an attempt to compare safety, cost-effectiveness of the procedure and post discharge follow-up. One hundred and two patients undergoing the procedures between May 1996 and October 1998 were analyzed. There were 65 patients in the partial sternotomy (MIV) group and 37 patients in the port–access (PAV) group. With the exception of a higher incidence of COPD in the MIV patients, there was no significant difference in pre-operative variables between these two groups. Results: Total operating room time, surgery time and cross-clamp time were significantly increased in the PAV group. The operative mortality of patients with MIV was 3%(n=2) while the PAV group was 8%(n=3) (P=ns). More new atrial fibrillation was found in the MIV (26% versus 5%, P=0.009). Otherwise, there was no significant complications observed in either group. During the 4–6 week follow-up, of those who were employed, 76% of MIV and 69% of PAV patients had returned to work. Of the retired patients more than 95% of the patients in both groups had resumed their daily routine activity. Importantly, the study showed PAV patients returned to work about 4 weeks sooner than MIV patients. Conclusions: MIV approach is more ‘surgeon friendly' and can be carried out without increased intra-operative resource utilization. The PAV approach requires formal training and capital outlay for unique equipment, disposable and ancillary procedures. From a financial perspective, if the PAV technique is to become widely accepted intra-operative efficiencies must be maximized, post-operative fast-tract protocol must be utilized, financial expenditures for disposable equipment must decrease and requirement of ancillary procedures must be reduced.
Key Words: Partial sternotomy • Port-access
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1. Introduction
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Since the inception of port-access valve surgery, it has been presumed that there is less pain, an improved cosmetic result, and that the procedure can be performed safely, effectively and with lower cost. Utilizing our own experience over the past 18 months with minimally invasive valve (MIV) and port–access valve (PAV) surgery, this review attempts to compare these two techniques. Short-term clinical outcomes and complications are compared, including pre-, intra-, and post-operative variables. Particular attention is devoted to the safety and technical aspects of the procedures and the post-discharge follow-up results.
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2. Materials and methods
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One hundred and two consecutive patients undergoing PAV or MIV procedures between May 1996 and October 1998 were analyzed. The data was collected using the defined Society of Thoracic Surgeon's National Cardiac Surgery Database (STS.NCSD) variables and definitions. The MIV group included 65 patients and the PAV group included 37 patients. When comparing demographics the PAV group was comprised of more males, of younger age and with an improved left ventricular function (Table 1
). With the exception of an increased incidence of COPD in the MIV group, there was no significant difference in pre-operative variables and risk factors between these groups (Table 2
). There were more mitral valve surgeries performed in the PAV group than in the MIV group (86% versus 19%). Of the MIV patients 3% had a double valve (aortic and mitral) procedure while there were none in the PAV category. Additionally, in the MIV group, one patient had a tricuspid valve repair and excision of a right atrial myxoma, and another had a right atrial myxoma and repair of a patent foramen ovale. All patients underwent total cardiopulmonary bypass utilizing a membrane oxygenator and centrifugal pump with mild hypothermia and retrograde blood or crystalloid cardioplegia. A double lumen endotracheal tube was used in all PAV procedures. A transjugular coronary sinus catheter and a pulmonary artery catheter were inserted by the anesthesiologist via a transesophageal echocardiography (TEE) in all PAV patients. Routine tracheal intubation, with or without a pulmonary artery catheter, was used in all MIV cases. Standard care and process was administered in the intensive care unit post-procedure with subsequent transfer to an intermediate care ward within 24 h or as directed by clinical status. Extubation was targeted within 4 h and determined by the institution's extubation protocol. Follow-up was conducted at 4–6 weeks post-discharge by phone or office visit. The follow-up focused on post-discharge re-admissions, time of return to daily activities, and work status.
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3. Statistical analysis
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Pre-operative, peri-operative, and post-operative variables were analyzed using the Student t-test, 
2 and Fisher's exact test. All variables were compared using univariate analysis. A P-value of less than 0.05 was considered to be statistically significant.
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4. Results
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Pre-operative co-morbidities are listed in Table 2. Total operating room time, surgery time (skin-to-skin) and cross-clamp time were significantly increased in the PAV group (Table 3
). Ventilation and ICU hours were greater in the PAV group, but without any statistical significance. The post-operative length of stay reflected similar results (PAV, 10±11.6; MIV, 8.4±7.9 days; P=ns). The operative mortality was 3% (n=2) for patients having MIV and 8% (n=3) in the PAV group, (P=ns). A greater incidence of new atrial fibrillation was seen in the MIV group (26% versus 5%, P=0.009). No significant difference was observed in the post-operative complications of stroke, re-operation for bleeding, heart block, pulmonary insufficiency or new renal failure (Table 4
). No complications from groin cannulation were experienced with the use of endo cardiopulmonary bypass system (Port–Access, Heartport Inc., Redwood City, CA) in the PAV group.
Rate of readmission to the hospital within 30-days of discharge was 15% for MIV and 8% for PAV (P>0.05). In the MIV group three patients were readmitted for pericardial window, one for pericardiocentesis, one for aggressive diuretic treatment for pericardial fluid, and one for atrial fibrillation. Four additional patients were readmitted with non-cardiac problems. In the PAV group one patient was readmitted for AV block, one required a permanent pacemaker, and one was treated for a non-cardiac problem. Completion rate at the 4–6 week follow-up period was 73% for the PAV population and 80% for MIV. Of the previously employed patients, 76% of the MIV patients and 69% of the PAV patients had returned to work. More than 95% of the retired patients in both groups had resumed their daily routine activities at the 4–6 week follow-up period.
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5. Discussion
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In the past few years, minimally invasive techniques for cardiac operations have grown in popularity. In particular, LAD bypass grafting was well suited to this approach. Subsequently, valvular operations were accessed utilizing a variety of minimally invasive techniques. In February of 1996, Carpentier and et al. [1] successfully performed the first video-assisted mitral valve repair through a mini-thoracotomy incision. Three months later, Chitwood and colleagues [2] also performed a direct vision mitral valve repair through a mini-thoracotomy. Soon others followed with additional approaches to mitral valve repair. Cosgrove and Sabik [3] reported their experience with the aortic valve procedure through a right-sided parasternal incision. Beginning in May 1996, our minimally invasive valve surgery program utilized a small skin incision (6–8 cm) with a partial sternotomy allowing a sternal spread of approximately 6 cm apart. This technique differs from the parasternal approach described by Cosgrove and Sabik [3] and the upper sternotomy incision described Gundry [4]. With this approach the right internal mammary artery is not sacrificed. Cannulation technique for MIV and conventional valve repair or replacement allows use of the standard aortic and right atrial cannulae. Recently, to improve exposure the venous cannula has been inserted via the femoral vein. The superior pulmonary vein vent and coronary sinus catheter are inserted with minor modifications from the conventional technique. This MIV technique does not necessitate intraoperative TEE to identify the location of the aortic root. Additionally, the MIV approach can be used for both aortic and mitral valve repair or replacements with single venous cannulation technique. The mitral valve is visualized and accessed through the dome of the atrium [5]. Our PAV cardiac surgery program began in September 1997. With this technique, the heart is approached via a small anterior thoracotomy incision through the fourth intercostal space [6].
This study was a non-randomized retrospective review of 102 consecutive patients. The majority of the MIV patients had aortic valve disease while the PAV patients had mitral valve disease. An argument of this review could be made that these were not comparable groups however, the purpose of this review was to examine the safety, efficacy, cost-effectiveness and short-term clinical outcomes of each technique. Intra-operative variables are noted in Table 3. The operating room, surgery, perfusion and cross-clamp times were documented in the computerized operating record along with the other intra-operative parameters such as estimated blood loss, use of blood products, and inotropes, etc. The perfusion and cross-clamp time of the PAV group were longer than the MIV group, respectively (109±24 versus 90±49 min (P<0.05) and 73±19 versus 60±39 min (P<0.05)). Skin-to-skin operative time was on the average 75 min longer (P<0.05) for the port-access approach. These extended times can be attributed to the preparation, positioning and repositioning of the cannula required for this PAV technique. Currently, we have eliminated fluoroscopy and are beginning to reduce total operating room times due to the experience and increased proficiencies of the anesthesiologist in placing the coronary sinus and pulmonary vent catheters. Extended operating room times and added intra-operative disposable and equipment could, theoretically, add an additional $6000 to $8000 (US dollars) to the hospital cost for these PAV procedures. The occurrence of new atrial fibrillation post-operatively was 26% in the MIV group as compared to 5% in the PAV group. Internal CQI studies have suggested that the occurrence of post-operative atrial fibrillation will extend the average hospital stay 2.2 days.
The 30-day mortality was 3% in MIV and 8% in the PAV group (P=ns). Although in comparing the occurrence of major post-operative complications, the safety and efficacy of these two procedures is supported. As noted on Table 4, except for new atrial fibrillation, there was no statistical significance in the major post-operative complications reported.
At 30-day follow-up, reasons for readmission such as cardiac, pulmonary and wound complications were noted. The occurrence of readmission was small thus analyzing the financial impact cannot provide a meaningful conclusion.
The partial sternotomy incision for MIV is only 6 cm long and has a spread of 6 cm compared to the full sternotomy of 30 cm long with the sternum-spread 25 cm wide. The MIV incision causes less damage to the muscles, ribs and joints, thereby minimizing post-operative chest wall pain and respiratory splinting. Thymectomy patients have similar minimally invasive incisions and are able to be discharged on post-operative day 2 however, it might not be feasible to expect this same length of stay for open heart surgery patients due to the inherent risk and morbidity of CPB.
Evaluation of the severity of incisional pain during the hospital stay is very subjective and can be misleading. Therefore, the degree of post-operative pain may be more appropriately evaluated by activity level at 4–6 weeks post surgery. Cosmetic results and early post-operative pain are also difficult to evaluate during the early post-operative period. The smaller skin incisions often times have more ecchymosis initially but become small and unnoticeable 2–3 weeks after surgery.
Of the employed patients, 76% of the MIV patients and 69% of the PAV patients returned to work. More than 95% of the retired patients in both groups resumed their daily routine activity. Our study showed PAV patients returned to work about 4 weeks sooner than MIV patients.
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6. Conclusion
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Port–access and MIV surgical approaches provide acceptable early post-operative morbidities as compared to the full sternotomy conventional approach. Both limited approaches make visualization of the target somewhat difficult. However, the MIV approach is more ‘surgeon friendly' and can be carried out without increased intra-operative resource utilization. The PAV approach requires formal training and capital outlay for unique equipment, disposable and ancillary procedures. Our results indicate (i) MIV and PAV techniques can be safely performed, (ii) current PAV technology limits the applicability of this approach for treatment of aortic valvular disease, (iii) MIV approach is appropriate for multi-valvular procedures, (iv) both procedures have allowed early return to work and resuming of daily activities and provide a more acceptable cosmesis when compared to the conventional approaches. From a financial perspective, for PAV technique to become widely accepted intra-operative efficiencies must be maximized, post-operative fast-track protocols must be utilized, financial expenditures for disposable equipment must be decreased and requirements for ancillary procedures need to be reduced.
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Footnotes
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Presented at the 2nd MITSIG International Symposium: Controversies in Cardiothoracic Surgery, Hong Kong ,November 20–21, 1998.
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References
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- Carpentier A, Loulmte D, Carpentier A. Open heart operation under videosurgery and minithoracotomy. First case (mitral valvuloplasty) operated with success. C R Acad Sci III 1996;319:219-223.[Medline]
- Chitwood W, Elbeery JR, Chapman WHH, Moran JM, Lust RL, Wooden WA, Deaton DH. Video-assisted minimally invasive mitral valve surgery: the ‘micro-mitral' operation. J Thorac Cardiovasc Surg 1997;113:413-414.[Free Full Text]
- Cosgrove III DM, Sabik JF. Minimally invasive approach for aortic valve operations. Ann Thorac Surg 1996;62:596-597.[Abstract/Free Full Text]
- Gundry SR, Stattuck OH, Razzouk AJ, del Rio MJ, Sardari FF, Bailey LL. Facile minimally invasive cardiac surgery via ministernotomy. Ann Thorac Surg 1998;65:1100-1104.[Abstract/Free Full Text]
- Arom KV, Emery RW, Nicoloff DM. Techniques for minimally invasive direct coronary artery bypass (MIDCAB) surgery. In: Emery RW, editor. Ministernotomy for cardiac surgery. Philadelphia: Hanley and Belfus Inc; 1997. pp. 43-48.
- Arom KV, Emery RW. Correspondence. Minimally invasive mitral operations. Ann Thorac Surg 1997;63:1209-1222.[Free Full Text]
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Abstract
1. Introduction
