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J Am Coll Cardiol, 2000; 36:1173-1177 © 2000 by the American College of Cardiology Foundation |
a Department of Cardiac Surgery, Medical University of Luebeck, Luebeck, Germany
Manuscript received August 6, 1999; revised manuscript received March 16, 2000, accepted April 28, 2000.
Reprint requests and correspondence: Prof. Dr. Hans-H. Sievers, Department of Cardiac Surgery, Medical University of Luebeck, Ratzeburger Allee 160, D-23538 Luebeck, Germany
schmidtk{at}medinf.mu-luebeck.de
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Abstract |
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The objective of this study was to compare the outcome of patients >60 years of age with younger patients after the Ross procedure.
BACKGROUND
Currently, the Ross procedure is performed predominantly in young patients. Main arguments against the Ross procedure in the elderly are the complexity of the operation and related risks. Experience with the Ross procedure in patients >60 years of age is scarce.
METHODS
Between February 1990 and August 1998, the Ross procedure was performed in 27 patients (15 men and 12 women) >60 years of age (mean 64.2 ± 3.1 years, range 60.5 to 70.6; group A) and in 84 patients (68 men, 12 women) <60 years of age (mean 43.8 ± 12.4 years, range 15.2 to 59.4; group B). Echocardiography was applied at a mean follow-up of 28.4 ± 21.0 and 25.2 ± 21.4 months, respectively, to determine hemodynamic variables (ejection fraction, fractional shortening, stroke volume, cardiac output), cardiac dimensions and autograft and homograft valve function.
RESULTS
There was one early and one late (esophageal bleeding) death in group B; the mortality rate was 0% in group A. One autograft was replaced because of a subvalvular aneurysm, and one patient was lost to follow-up (group B). There were no significant differences in cardiac dimensions, grade of insufficiencies across homografts and autografts and hemodynamic variables, except for a higher pressure gradient across the homograft in group B (maximal pressure gradient 11.3 ± 5.6 vs. 7.7 ± 4.6 mm Hg in group A). The median New York Heart Association functional class was I in both groups.
CONCLUSIONS
Our seven years of experiences (mean follow-up 28 months) indicate that the Ross procedure may be performed in selected patients >60 years of age without increased risk for mortality or complications in experienced centers.
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In 1993, an international registry was established (4). At present, more than 600 Ross procedures per year are performed worldwide in more than 104 centers. The current main indications for the Ross procedure are single valve pathology, mechanical or bioprosthetic valve failure, endocarditis limited to the aortic root and athletes or young adults in whom anticoagulation is contraindicated and optimal hemodynamic measures are desired, as well as patient age between 11 and 50 years (5,6). Absolute contraindications for aortic valve replacement with the pulmonary autograft are advanced three-vessel coronary artery disease (CAD), other extensive valve pathology requiring replacement, severely depressed left ventricular (LV) function, multisystemic organ failure (e.g., pulmonary, renal, hepatic), pulmonary valve pathology (congenital, acquired, iatrogenic) and Marfan syndrome (5). There is controversy with regard to the upper age limit (>60 years of age) (5).
A main argument against the Ross procedure in elderly patients is the longer and more complex operation ("two valve surgery") compared with a simple aortic valve replacement, and the surgery-related complications in these patients. Other authors argue that a decline in the elastic integrity of the pulmonary valve beyond age 40 to 50 years may provide an unsuitable substitute for aortic valve replacement, with unacceptable long-term results in patients >50 years of age (5).
However, the Ross procedure has a number of desirable qualities, and it therefore becomes an attractive alternative to conventional aortic valve replacement with mechanical or biologic prostheses, even in the elderly. These qualities include autologous tissue with documented long-term viability (7), optimal hemodynamic data, regeneration capacity with a possible resistance to infection, lack of valve noise, low valve failure and thus reintervention rate, freedom from anticoagulation and anticoagulation-related hemorrhage and a low incidence of thromboembolic complications.
Experience with the Ross procedure in patients >60 years of age is scarce. In this report, we describe our experience in replacing the diseased aortic valve with a pulmonary autograft in 27 patients >60 years of age, as well as the results of an echocardiographic study assessing hemodynamic data and valve function of autografts and homografts in our elderly patients versus a patient cohort of 84 patients <60 years of age.
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Methods |
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Operative techniques. Three techniques were used for implanting the autologous pulmonary valve: 1) total aortic root replacement; 2) inclusion; and 3) the subcoronary technique. The operative techniques are described in detail elsewhere (8,9). Using the subcoronary technique, special care was taken to match the size of the autograft to the aortic root. A size difference up to 3 mm was accepted. Otherwise, a reduction annuloplasty, according to David (10), was performed, or the root at the sinotubular junction was adjusted to the autograft diameter during closure of the aortotomy that extended into the noncoronary sinus. All patients were operated on under standard cardiopulmonary bypass conditions with a membrane oxygenator (Hollow Fiber Oxygenator, Spiral Gold, Baxter, Puerto Rico), at moderate systemic hypothermia with cold crystalloid cardioplegia (St. Thomas’ Hospital solution) for myocardial protection.
Echocardiographic data acquisition and measurements. Informed, written consent was obtained before echocardiography. The investigative procedures were in accordance with institutional guidelines. Transthoracic echocardiograms were obtained on a Hewlett-Packard Sonos 2500 system with 2.5- and 1.9-MHz ultrasound transducers during routine follow-up and recorded on VHS videotape. A modified electrocardiographic (ECG) lead I was continuously recorded. Blood pressure (BP) was measured by cuff sphygmomanometry (Dinamap, Siemens, Erlangen, Germany).
Two-dimensional echocardiography. The morphology of the aortic cusps was examined, and measurements of standard dimensions were made in standard longitudinal and cross-sectional views. Left ventricular end-systolic and end-diastolic volumes were obtained from apical two- and four-chamber views. Diastole was defined as the beginning of the QRS complex on the simultaneous ECG recording.
Continuous wave, pulsed and color flow Doppler images. Maximal velocities across the aortic and pulmonary valve were obtained by using a continuous wave Doppler imaging transducer. To obtain the highest velocity across the aortic valve, the independent (Pedoff) 1.9-MHz nonimaging transducer was also used. The maximal pressure gradient was calculated using the modified Bernoulli equation.
To assess aortic regurgitation (AR), pulsed wave Doppler and color flow Doppler were used for mapping the LV outflow tract, and continuous spectral Doppler was applied to measure the deceleration slope and pressure half-time of the aortic regurgitant jet. Furthermore, AR was quantitated by measuring the jet height at the valve orifice and comparing it with the height of the LV outflow tract according to the method of Perry et al. (11): ratio of 1% to 24% = grade I; 25% to 46% = grade II; 47% to 64% = grade III; and 
65% = grade IV. For assessment of pulmonary regurgitation, pulsed wave, continuous wave and color Doppler were performed. Semiquantitative assessment of its severity was based on the length and width of the regurgitant jet and the distance it reaches into the right ventricular outflow tract on the parasternal short-axis view.
Statistical analysis. Categoric data are given as total numbers and relative frequencies, and continuous data as the mean value ± SD, unless otherwise stated. Different groups were compared using the t test or the Mann-Whitney U test. For correlation analysis, the Spearman rank correlation coefficient was calculated. A p value < 0.05 was considered to indicate statistical significance. All tests were two-sided. Regression analysis was carried out for each variable so that any effect of variable length of follow-up time was factored in when comparing the two age groups; the results obtained were similar to the unadjusted results shown in Table 2. Statistics were performed using statistical software (SPSS for Windows 8.0, SPSS Inc.).
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Results |
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In group B, one patient died 10 days after the operation (hospital mortality rate <1%), and one patient died 18 months after the operation because of esophageal bleeding. In another patient, replacement of the free-standing autograft with a mechanical aortic valve prosthesis was necessary due to an aortic subvalvular aneurysm six years after root replacement. No thromboembolic events occurred in the patients in group B. One patient was lost to follow-up. Thus, group B comprises 80 patients at echocardiographic follow-up. The median of New York Heart Association functional class was I in both groups.
Hemodynamic data and valve function. Postoperative hemodynamic data are depicted in Table 2. Heart rate, stroke volume, cardiac output, ejection fraction and LV dimensions were comparable between the groups; only the systolic BP was significantly higher in the elderly. Also, the maximal pressure gradient across the homograft was significantly higher in group B (11.3 ± 5.6 mm Hg) than in group A (7.7 ± 4.6 mm Hg; p = 0.004). There was a weak but significant correlation (p < 0.001) between the duration of follow-up and the pressure gradient across the homograft in group B (r = 0.391) (Fig. 1), but not in group A (r = 0.274, p = 0.176) (Fig. 1).
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Discussion |
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Choice of valve substitute in elderly patients.
The Ross procedure is generally accepted for patients <50 years of age. The choice of a prosthesis for aortic valve replacement, particularly for patients between 60 and 70 years of age, remains controversial. It is determined, among other factors, by the intrinsic characteristics of the replacement device and the patient group to be operated on, as well as by the experience of the surgical team. Mechanical valves that offer extended durability have the constant risk of valve-related complications (12,13). In many cardiac surgical centers, the mechanical valve is not the valve of choice for elderly patients; instead it is a bioprosthesis, whether stented or stentless. The advantages of bioprostheses include a lower incidence of thromboembolism and valve thrombosis and the relative freedom from the risk of anticoagulant-related hemorrhage. A bioprosthesis is reported to be prone to reduced degeneration and structural valve failure in older patients. Cohen et al. (14) demonstrated that at 12 years, the freedom from primary tissue failure was lower in patients <65 years of age than in those 65 years of age. Burr et al. (15) reported freedom from structural valve deterioration of a bioprosthesis in aortic position of 94.9 ± 1.8% at 10 years for patients 65 to 69 years old (15).
Valve reoperation. Nevertheless, there is a considerable risk that the valve will require re-replacement if a bioprosthesis is used in patients between 60 and 70 years of age. Especially after 12 years postoperatively, the freedom from valve degeneration decreases exponentially (15). Consequently, most patients will need reoperation at an advanced age, between 75 and 80 years. At such an age, the indication for reoperation is restricted, and the risk that an operation will be needed is increased. It is reported to be as high as 14% to 25% in patients >70 years of age (16). In many reports, valve failure indicates replacement of the bioprosthesis. However, not only the reoperation, but also the valve degeneration that produces a hemodynamic burden on the LV, without fulfilling the criteria for reoperation, may have some influence on ventricular function and probably the longevity of the patient. Therefore, it is desirable that these elderly patients receive a valve substitute with a reduced rate of degeneration in order to prevent reoperation and functional impairment. In addition, older patients hope to be operated on only once and to be free of complications and anticoagulation. Furthermore, socially integrating these patients as much as possible, so they are active and productive persons, reduces the time span of senescence. These factors, taken together, suggest that there is a meaningful rationale for older patients to receive the Ross procedure. However, patients must be selected for their level of activity and general status, social situation, life expectancy and comorbidity to outweigh the risks versus the benefits of this special surgical procedure in comparison with the excellent results of bioprostheses. Reported freedom from reoperation after the Ross procedure at 20 years was 75% for the autograft and 80% for the homograft (17). Only one of our patients had to be reoperated on because of a subvalvular aneurysm; the leaflets were macroscopically intact. These data are superior to those for bioprostheses and most likely can be projected into the advanced-age group.
Autograft function. We did not find significant autograft dysfunction in group A. Whether this reduced rate of degeneration of the autograft will stand the test of time remains to be established. The longest follow-up time in group A was 83.1 months, and in this patient, there was no significant insufficiency and no pressure gradient, suggesting excellent hemodynamic data. Most patients had no, or mild, aortic insufficiency, with no difference between the groups. The high incidence of no AR is probably related to the exact size matching at the base and sinotubular junction. In conjunction with the low pressure gradients, these hemodynamic data may beneficially influence the long-term function of the LV and probably patient survival as well.
Homograft function. It is interesting that we found a significantly lower pressure gradient across the homograft in group A. Whether this is related to a reduced immunologic response with increasing age and a resulting lower degree of shrinkage of the homograft as a source for development of a pressure gradient remains to be determined. Vogt et al. (18) reported an attenuated immunologic reaction of the allografts in elderly patients compared with children. Furthermore, there was no authentic correlation between the duration of follow-up and the pressure gradient across the homograft in the elderly. In the younger patients, this correlation was weak but significant, indicating that in this age group there is a tendency for a time-related increase in the pressure gradient across the homograft. Therefore, close follow-up, especially in the younger patients, is desirable. Serial longer term follow-up studies are necessary to clarify this item. In this regard, Moidl et al. (19) reported an increase in flow velocities across the homograft up to one year after the operation, suggesting a dynamic graft-related process. It must be considered, however, that in our series the maximal pressure gradient across the homograft did not exceed 22 mm Hg, even after a maximal follow-up period of eight years, indicating that the assumed valve-related stenotic process is probably of minor significance in the majority of patients.
Operative risk. In group A, we could not find an increased operative risk. There was no evidence that the longer ischemic time of the myocardium had an impact on the myocardial function of either group A or group B. Normal values were found for LV ejection fraction, cardiac output and LV dimensions in both groups after the operation. Whether this holds true for patients with more reduced preoperative LV function remains questionable. For these patients, bioprostheses or mechanical valves are probably the better surgical procedure.
Thromboembolic events. Two thromboembolic events occurred in group A. In the first patient, the thromboembolic event may be caused by an atrial thrombus that was detected postoperatively. In the other patient, the transient ischemic attack can be attributed to the pledgets that we used for fixation of the commissures in the first patients or to the atherosclerotic aging process. The exact source of embolism is difficult to define, especially in the advanced age group. Prencipe et al. (20) reported a prevalence of stroke of 7.3% in patients >65 years of age without heart disease.
Conclusions. The Ross procedure provides excellent results in elderly selected patients up to 70 years of age, in terms of clinical status, hemodynamic data and semilunar valve function. The pressure gradient across the homograft was significantly lower in the older age group. Longer follow-up periods with larger numbers of patients are necessary for final judgment of this extended indication with the Ross procedure, particularly if these valve-related advantages have beneficial effects on patient survival.
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Acknowledgments |
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  M. Salehi, R. Sattarzadeh, A. A. Soleimani, H. Radmehr, J. Mirhosseini, and M. Sanatkar Far The Ross Operation: Clinical Results and Echocardiographic Findings Asian Cardiovasc Thorac Ann, February 1, 2007; 15(1): 30 - 34. [Abstract] [Full Text] [PDF]
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