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Aortic and mitral balloon valvuloplasty: emergence of a new percutaneous technique
International Journal of Cardiology, 16 (1987) 227-233 Elsevier
227
IJC 00572
Editorial
Aortic and mitral balloon valvuloplasty: emergence of a new percutaneous technique David R. Holmes, Jr., Rick A. Nishimura,
Guy S. Reeder
Divisron of Cardiovascular Diseases and Internal Medicine, Mayo Clinic and Mqo Rochester, Minnesota, U.S.A.
Key words: Valvuloplasty;
Aortic
stenosis;
Mitral
Foundation,
stenosis
The practice of modern cardiology is changing rapidly. The catalysts for these changes have been the expanded body of knowledge about the mechanisms and natural history of specific diseases and the development of new concepts and technologies that can be applied for treatment. Since 1977, the development and widespread application of balloon inflation catheters have added a new procedure to the cardiologist’s armamentarium. Initially used for peripheral vascular and coronary artery disease, balloon dilatation now has other applications. For the past 1: years, balloon inflation (or balloon valvuloplasty) has been used for the treatment of aortic and mitral stenosis [l-5]. The eventual role of this approach will depend on its safety and efficacy in comparison with established surgical procedures. The concept of dilatation of aortic and mitral stenosis is not new; before the development of current prosthetic devices, dilatation was used for both aortic and mitral valve disease. For patients with aortic stenosis, the results with a variety of instruments were suboptimal and were characterized by calcific embolization, inadequate relief of gradient, and excessive trauma to the valve apparatus. For physicians and surgeons involved in the early development of this approach in the 1950s the current rebirth of interest evokes some concern. For mitral stenosis, the story has been quite different. Commissurotomy has been used successfully for the past 20 years, with excellent long-term results in selected patients. Why the interest in balloon valvuloplasty or balloon commissurotomy? Although surgical valve replacement or repair is commonly performed. it is a major surgical procedure with attendant morbidity and mortality. In some patients, these risks are
Correspondence to: D.R. Holmes, U.S.A.
0167-5273/87/$03.50
Jr., M.D., Mayo Clinic, 200 First Street SW. Rochester,
0 1987 Elsevier Science Publishers
B.V. (Biomedical
Division)
MN 55905,
228
high enough that the patient, the surgeon, or the attending physician wants to either defer or avoid surgery. In addition, no prosthesis is perfect; all have advantages and disadvantages. Some types have poor hemodynamic characteristics and are inherently obstructive, whereas others deteriorate with time and require repeat valve replacement with its attendant increased risk. Finally, the potential for thromboembolic complications exists in various degrees, irrespective of the use of anticoagulants.
Six Questions For these reasons, among others, balloon valvuloplasty has attracted a great deal of interest. Before the technique should be accepted or widely used, several questions need to be addressed. (1) What is the mechanism of dilatation? (2) Is it safe? (3) Is it difficult? (4) Is it effective? (5) Does it result in valvular insufficiency? (6) What are the long-term benefits ? Most of these questions cannot be fully answered as yet, and considerable further study is required. What is the Mechanism
of Dilatation?
The mechanism of dilatation depends on the anatomic substrate. For mitral stenosis, dilatation yields a commissurotomy type of result, with splitting along the lines of the fused, thickened commissures. For this reason, some investigators have thought that the procedure for mitral stenosis is best termed “balloon commissurotomy” or “balloon valvotomy” rather than “balloon valvuloplasty.” For the aortic valve, the anatomic substrate is more variable. In our practice, . about 50% of adults undergoing aortic valve replacement have senile, calcific degenerative aortic stenosis, characterized by calcific deposits that limit cusp mobility but do not result in commissural fusion. In a minority of patients, about 30%, the valve is bicuspid. In only about 20% of our patients is the stenosis related to prior inflammation, for example, rheumatic heart disease with commissural fusion [6]. The mechanisms of dilatation vary, depending on the anatomic substrate. Mechanisms of dilatation include fracture of the calcific plates, splitting of commissural fusion, if it is present, and stretching and displacement of rigid valve cusps. Is Dilatation
Safe?
The issue of safety has multiple facets, including patient tolerance, hemodynamic stability or instability, and complications, such as arterial injury, thromboembolism, valvular insufficiency, myocardial damage, and even death. The specific patient populations in whom dilatation is attempted are an important factor. Attempts at palliative aortic valve dilatation in a 95-year-old patient with severe heart failure and other associated diseases may be less well tolerated than dilatation in an otherwise healthy 60- or 70-year-old with uncomplicated aortic stenosis. Obstructing aortic outflow or mitral inflow during balloon inflation clearly results in adverse hemodynamic changes. In most patients, aortic balloon inflation is
229
surprisingly well tolerated without severe hypotension, loss of consciousness, or severe angina. When a circular balloon is inflated in the triangular orifice of a calcific tricuspid aortic valve, there is still room for some aortic flow through intact commissures. In these patients, the balloon may be inflated for up to 1 to 2 minutes. In a minority of patients, there is significant hemodynamic instability, with marked decrease in systemic pressure to < 70 mm Hg, which limits balloon inflation time. Perhaps they have rheumatic or bicuspid disease or less myocardial reserve. For the patients with mitral stenosis, in our experience. inflation of two large balloons simultaneously is tolerated for a shorter period and usually is limited to only 15 to 20 seconds. During this time, marked systemic hypotension and pulmonary hypertension are commonly seen, no doubt because of severe mitral obstruction. These effects, however, are quickly relieved after balloon deflation. The complications associated with the procedure depend in part on the route taken (transvenous and transseptal or retrograde arterial) and whether associated arterial disease is present. In elderly patients with tortuous calcified iliac vessels, passage of the large, rather stiff catheters is often difficult. For mitral valve dilatation, a modified transseptal procedure is required. Although a small atria1 septal defect is created during balloon passage, it has not resulted in a clinical problem. The potential for thromboembolism is of most concern. Emboli could result from undetected left atria1 thrombi or fragmentation of calcium deposits. Another source of emboli is the need for prolonged intra-aortic guide wire manipulation during placement of the balloon catheters. Full heparinization minimizes this potential. Fortunately, embolization has been rare, occurring in < 1% to 2%. For patients with mitral valve disease, two-dimensional echocardiography is essential in an attempt to exclude patients with left atria1 thrombi; patients with a history of thromboembolism should be excluded. The use of anticoagulants in patients prior to mitral valvuloplasty may also help to decrease the potential of thromboembolism. For patients with aortic valve disease, calcific embolization is very rare. In postmortem studies, fragmentation of calcium plates is seen, but the deposits remain subintimal [3]. In the French Registry experience, a procedure-related stroke was seen in 2% [7]. Other complications, such as myocardial perforation and arterial laceration, have been reported but are uncommon. When these occur, however, they are often associated with increased morbidity and even mortality. Mortality related to aortic valve dilatation has been reported. It is in part related to the clinical subset. In patients who are critically ill with congestive heart failure and low perfusion, the potential for death during hospitalization is increased. In experienced centers in the French Registry experience, the in-hospital mortality was 4% [7]. Is Dilatation
Difficult?
The ease with which dilatation can be learned and performed may affect the frequency with which it is attempted. With percutaneous transluminal coronary angioplasty, the concept of a learning curve has been well described; it is probable that a similar concept will apply for valvular dilatation. The skills and experience required for a safe transseptal approach, which is needed for mitral valve dilatation.
230
are not possessed by a large number of angiographers. A definite learning curve exists for this. The learning curve for aortic valve dilatation may be less steep because retrograde placement of catheters across the aortic valve is more commonly performed. Still, the necessary manipulation of guide wires, selection of the appropriate combination of balloon sizes, and other technical details require expertise and judgment that should not be underestimated. Is Dilatation Effective? The definition of success and effectiveness of balloon valvuloplasty has yet to be determined. The goals of the procedure vary and depend on the specific patient. In the elderly high-risk surgical patient with severe aortic stenosis, congestive heart failure, and other major medical problems, the goals of dilatation are clearly palliative. They include an attempt to modestly reduce the transaortic gradient and therefore alleviate the heart failure. In such a patient, improving the gradient from 80 mm Hg before the procedure to 40 mm Hg after might be all that is needed for a good clinical result. This result is different from that in the young, active good surgical candidate with severe aortic stenosis who wants to return to vigorous activity. In this patient, a reduction in gradient from 80 to 40 mm Hg may not be enough to alleviate either the patient’s symptoms or the physician’s concerns about long-term outcome. The definition of success is arbitrary. One commonly used definition for successful aortic valve dilatation is a reduction in gradient by 50% or an improvement in aortic valve area by 25%. There are few published reports of what is actually obtained. In the recent multicenter French Registry experience, Cribier et al. [7] reported results in 442 patients. In this group, there was a reduction in the mean gradient from 78 f 29 to 37 k 19 mm Hg and improvement in the aortic valve area from 0.46 f 0.18 to 0.79 + 0.33 cm2. In some patients, such improvement has resulted in major improvement in left ventricular function and excellent clinical relief of symptoms. In a substantial number of patients, although dilatation is successful, significant residual stenosis of perhaps mild or even moderate degree remains. Whether this result will be associated with long-term clinical improvement is uncertain. For mitral stenosis, again the definition of success is arbitrary. In our institution, we attempt to achieve a final end-diastolic gradient of < 5 mm Hg and a mitral valve area of 2 1.5-2 cm2. This definition is based in part on what a surgical commissurotomy or valve replacement should achieve. In the young patient with isolated mitral stenosis, attempts should be made to achieve the optimal result rather than modest palliative improvement. Does Dilatation Result in Valvular Insufficiency? Concerns about the development of insufficiency are based on surgical experience in which mitral insufficiency developed in some patients undergoing mitral commissurotomy and aortic insufficiency developed in a significant number of
231
patients undergoing early attempted open aortic valve dilatation. In practice, these have not been major clinical problems. Currently, the procedure is restricted to patients with no or only mild insufficiency. In these patients, it is uncommon for significant insufficiency to develop. In some patients, a mild worsening of insufficiency may occur. Paradoxically, aortic insufficiency has actually decreased in some patients after dilatation. In these individuals, the calcific deposits presumably interfere with normal coaptation of the leaflets. Improved mobility of the leaflets after dilatation facilitates normal coaptation. What are the Long-Term
Benefits?
Follow-up data for these patients are accumulating but remain limited. Restenosis will be seen. It has been well documented in patients after surgical commissurotomy. Heger et al. [8] documented a 28% restenosis rate in 18 patients who underwent repeat evaluation at a mean of 12.2 years after successful mitral commissurotomy. Fortunately in patients with restenosis, repeat dilatation should be possible. For aortic stenosis, restenosis rates cannot be accurately estimated. If the mechanism of dilatation is merely fracture of calcific plates, rigidity and immobility might well return with time. The interval for this to take place is unknown. Fortunately, recurrence should also be amenable to repeat dilatation. Although much needs to be learned about the long-term benefits, in the shorter term significant clinical improvement has been seen, with relief of symptoms, decreased need for medications, and a low incidence of late procedure-related complications. In some patients with only a modest improvement in calculated aortic valve area, left ventricular function has improved greatly, an indication that a physiologically important improvement in orifice size has been effected.
Selection
Criteria
Current selection criteria are based on the admittedly limited experience achieved to date. For mitral stenosis, ideal patients are those who are candidates for commissurotomy because of isolated mitral stenosis with no or only mild mitral insufficiency, pliable leaflets, and calcification that is not severe. On the basis of the long surgical experience with commissurotomy in these patients, mitral balloon dilatation can be considered a treatment of choice in centers experienced with the technique. Exclusion criteria include other valvular heart disease or coronary artery disease requiring surgery, significant mitral insufficiency, left atria1 thrombi, substantial subvalvular-chordal fusion, and inexperience with the procedure. For the patient with a severely calcified mitral apparatus, the procedure can be done but the results may be less than ideal. For aortic stenosis, we currently restrict dilatation to three groups of patients. (1) Those who because of associated severe disease are not surgical candidates. The number of these patients will vary from center to center; however, in each center there will be patients in this category. (2) Those who are at high risk for surgery. Some of these patients will have associated diseases, others will be very elderly, and
232
others will have severely compromised left ventricular function. In some of these patients, the risk of surgery may range from 10 to 25% [9,10]. For this group, palliative aortic valve dilatation is also offered. (3) Those with severe aortic stenosis who are good surgical candidates but who decline aortic valve replacement. Dilatation can be offered as an alternative, and many such patients will accept it. Prior to the development of valvuloplasty, the only alternative to surgical therapy was medical therapy. This latter therapy is not satisfactory. We have reviewed the outcome in patients seen at our institution between 1978 and 1985, who had severe aortic stenosis but did not undergo aortic valve replacement. There were 46 patients with a mean age of 77.2 years. Actuarial survival at 1, 2 and 3 years was 56, 37, and 25%, respectively, compared to age-matched controls in whom the survival at the same time periods was 93, 85, and 77% [ll]. The very poor survival in this group of patients with medical therapy for severe aortic stenosis mandates the development of techniques such as valvuloplasty.
Conclusion Although aortic and mitral valve dilatation is rapidly emerging as a new percutaneous technique, the procedure is still in its infancy. The equipment requires considerable modification to improve the ease, efficacy, and safety of the procedure. For isolated mitral stenosis, this procedure should become the treatment of choice in carefully selected individuals. For aortic stenosis, it is only palliative at present. With this “4-minute-mile barrier” broken and the potential for modification of valvular stenoses by nonsurgical mechanical means demonstrated, newer and more effective treatment strategies should evolve.
References 1 Cribier A, Savin T, Saoudi N, Rocha P, Berland J, Letac B. Percutaneous transluminal valvuloplasty of acquired aortic stenosis in elderly patients: an alternative to valve replacement? Lancet 1986;1:63-67. 2 Lock JE, Khalilullah M, Shrivastava S, Bahl V, Keane JF. Percutaneous catheter commissurotomy in rheumatic mitral stenosis. N Engl J Med 1985;313:1515-1518. 3 McKay RG, Safian RD, Lock JE, et al. Balloon dilatation of calcific aortic stenosis in elderly patients: postmortem, intraoperative, and percutaneous valvuloplasty studies. Circulation 1986;74:119-125. 4 Palacios IF, Lock JE, Keane JF, Block PC. Percutaneous transvenous balloon valvotomy in a patient with severe calcific mitral stenosis. J Am Co11 Cardiol 1986;7:1416-1419. 5 McKay RG, Lock JE, Keane JF, Safian RD, Aroesty JM, Grossman W. Percutaneous mitral valvuloplasty in an adult patient with calcific rheumatic mitral stenosis. J Am Co11 Cardiol 1986;7:1410-1415. 6 Passik CS, Ackermann DM, Pluth JR, Edwards WD. Temporal changes in the causes of aortic stenosis: a surgical pathologic study of 646 cases. Mayo Clin Proc 1987;62:119-123. 7 Cribier A, Letac B, Lancelin B, et al. Percutaneous balloon valvuloplasty (PBV) for acquired aortic stenosis: preliminary immediate results of the French Registry (abstract). Circulation 1986;74(suppl 2):208. 8 Heger JJ, Warm LS, Weyman AE, Dillon JC, Feigenbaum H. Long-term changes in mitral valve area after successful mitral commissurotomy. Circulation 1979:59:443-448.
233 9 Smith N, McAnulty JH, Rahimtoola SH. Severe aortic stenosis with impaired left ventricular function and clinical heart failure: results of valve replacement. Circulation 1978;58:255-264, 10 O’Toole JD, Geiser EA, Reddy PS, Curtiss EI, Landfair RM. Effect of preoperative ejection fraction on survival and hemodynamic improvement following aortic valve replacement. Circulation 1978;58:1175-1184. 11 O’Keefe JH, Vlietstra RE, Holmes DR. Bailey KR. Natural history of candidates for balloon aortic valvuloplasty. J Am Co11 Cardiol 1987;9:195A.
227
IJC 00572
Editorial
Aortic and mitral balloon valvuloplasty: emergence of a new percutaneous technique David R. Holmes, Jr., Rick A. Nishimura,
Guy S. Reeder
Divisron of Cardiovascular Diseases and Internal Medicine, Mayo Clinic and Mqo Rochester, Minnesota, U.S.A.
Key words: Valvuloplasty;
Aortic
stenosis;
Mitral
Foundation,
stenosis
The practice of modern cardiology is changing rapidly. The catalysts for these changes have been the expanded body of knowledge about the mechanisms and natural history of specific diseases and the development of new concepts and technologies that can be applied for treatment. Since 1977, the development and widespread application of balloon inflation catheters have added a new procedure to the cardiologist’s armamentarium. Initially used for peripheral vascular and coronary artery disease, balloon dilatation now has other applications. For the past 1: years, balloon inflation (or balloon valvuloplasty) has been used for the treatment of aortic and mitral stenosis [l-5]. The eventual role of this approach will depend on its safety and efficacy in comparison with established surgical procedures. The concept of dilatation of aortic and mitral stenosis is not new; before the development of current prosthetic devices, dilatation was used for both aortic and mitral valve disease. For patients with aortic stenosis, the results with a variety of instruments were suboptimal and were characterized by calcific embolization, inadequate relief of gradient, and excessive trauma to the valve apparatus. For physicians and surgeons involved in the early development of this approach in the 1950s the current rebirth of interest evokes some concern. For mitral stenosis, the story has been quite different. Commissurotomy has been used successfully for the past 20 years, with excellent long-term results in selected patients. Why the interest in balloon valvuloplasty or balloon commissurotomy? Although surgical valve replacement or repair is commonly performed. it is a major surgical procedure with attendant morbidity and mortality. In some patients, these risks are
Correspondence to: D.R. Holmes, U.S.A.
0167-5273/87/$03.50
Jr., M.D., Mayo Clinic, 200 First Street SW. Rochester,
0 1987 Elsevier Science Publishers
B.V. (Biomedical
Division)
MN 55905,
228
high enough that the patient, the surgeon, or the attending physician wants to either defer or avoid surgery. In addition, no prosthesis is perfect; all have advantages and disadvantages. Some types have poor hemodynamic characteristics and are inherently obstructive, whereas others deteriorate with time and require repeat valve replacement with its attendant increased risk. Finally, the potential for thromboembolic complications exists in various degrees, irrespective of the use of anticoagulants.
Six Questions For these reasons, among others, balloon valvuloplasty has attracted a great deal of interest. Before the technique should be accepted or widely used, several questions need to be addressed. (1) What is the mechanism of dilatation? (2) Is it safe? (3) Is it difficult? (4) Is it effective? (5) Does it result in valvular insufficiency? (6) What are the long-term benefits ? Most of these questions cannot be fully answered as yet, and considerable further study is required. What is the Mechanism
of Dilatation?
The mechanism of dilatation depends on the anatomic substrate. For mitral stenosis, dilatation yields a commissurotomy type of result, with splitting along the lines of the fused, thickened commissures. For this reason, some investigators have thought that the procedure for mitral stenosis is best termed “balloon commissurotomy” or “balloon valvotomy” rather than “balloon valvuloplasty.” For the aortic valve, the anatomic substrate is more variable. In our practice, . about 50% of adults undergoing aortic valve replacement have senile, calcific degenerative aortic stenosis, characterized by calcific deposits that limit cusp mobility but do not result in commissural fusion. In a minority of patients, about 30%, the valve is bicuspid. In only about 20% of our patients is the stenosis related to prior inflammation, for example, rheumatic heart disease with commissural fusion [6]. The mechanisms of dilatation vary, depending on the anatomic substrate. Mechanisms of dilatation include fracture of the calcific plates, splitting of commissural fusion, if it is present, and stretching and displacement of rigid valve cusps. Is Dilatation
Safe?
The issue of safety has multiple facets, including patient tolerance, hemodynamic stability or instability, and complications, such as arterial injury, thromboembolism, valvular insufficiency, myocardial damage, and even death. The specific patient populations in whom dilatation is attempted are an important factor. Attempts at palliative aortic valve dilatation in a 95-year-old patient with severe heart failure and other associated diseases may be less well tolerated than dilatation in an otherwise healthy 60- or 70-year-old with uncomplicated aortic stenosis. Obstructing aortic outflow or mitral inflow during balloon inflation clearly results in adverse hemodynamic changes. In most patients, aortic balloon inflation is
229
surprisingly well tolerated without severe hypotension, loss of consciousness, or severe angina. When a circular balloon is inflated in the triangular orifice of a calcific tricuspid aortic valve, there is still room for some aortic flow through intact commissures. In these patients, the balloon may be inflated for up to 1 to 2 minutes. In a minority of patients, there is significant hemodynamic instability, with marked decrease in systemic pressure to < 70 mm Hg, which limits balloon inflation time. Perhaps they have rheumatic or bicuspid disease or less myocardial reserve. For the patients with mitral stenosis, in our experience. inflation of two large balloons simultaneously is tolerated for a shorter period and usually is limited to only 15 to 20 seconds. During this time, marked systemic hypotension and pulmonary hypertension are commonly seen, no doubt because of severe mitral obstruction. These effects, however, are quickly relieved after balloon deflation. The complications associated with the procedure depend in part on the route taken (transvenous and transseptal or retrograde arterial) and whether associated arterial disease is present. In elderly patients with tortuous calcified iliac vessels, passage of the large, rather stiff catheters is often difficult. For mitral valve dilatation, a modified transseptal procedure is required. Although a small atria1 septal defect is created during balloon passage, it has not resulted in a clinical problem. The potential for thromboembolism is of most concern. Emboli could result from undetected left atria1 thrombi or fragmentation of calcium deposits. Another source of emboli is the need for prolonged intra-aortic guide wire manipulation during placement of the balloon catheters. Full heparinization minimizes this potential. Fortunately, embolization has been rare, occurring in < 1% to 2%. For patients with mitral valve disease, two-dimensional echocardiography is essential in an attempt to exclude patients with left atria1 thrombi; patients with a history of thromboembolism should be excluded. The use of anticoagulants in patients prior to mitral valvuloplasty may also help to decrease the potential of thromboembolism. For patients with aortic valve disease, calcific embolization is very rare. In postmortem studies, fragmentation of calcium plates is seen, but the deposits remain subintimal [3]. In the French Registry experience, a procedure-related stroke was seen in 2% [7]. Other complications, such as myocardial perforation and arterial laceration, have been reported but are uncommon. When these occur, however, they are often associated with increased morbidity and even mortality. Mortality related to aortic valve dilatation has been reported. It is in part related to the clinical subset. In patients who are critically ill with congestive heart failure and low perfusion, the potential for death during hospitalization is increased. In experienced centers in the French Registry experience, the in-hospital mortality was 4% [7]. Is Dilatation
Difficult?
The ease with which dilatation can be learned and performed may affect the frequency with which it is attempted. With percutaneous transluminal coronary angioplasty, the concept of a learning curve has been well described; it is probable that a similar concept will apply for valvular dilatation. The skills and experience required for a safe transseptal approach, which is needed for mitral valve dilatation.
230
are not possessed by a large number of angiographers. A definite learning curve exists for this. The learning curve for aortic valve dilatation may be less steep because retrograde placement of catheters across the aortic valve is more commonly performed. Still, the necessary manipulation of guide wires, selection of the appropriate combination of balloon sizes, and other technical details require expertise and judgment that should not be underestimated. Is Dilatation Effective? The definition of success and effectiveness of balloon valvuloplasty has yet to be determined. The goals of the procedure vary and depend on the specific patient. In the elderly high-risk surgical patient with severe aortic stenosis, congestive heart failure, and other major medical problems, the goals of dilatation are clearly palliative. They include an attempt to modestly reduce the transaortic gradient and therefore alleviate the heart failure. In such a patient, improving the gradient from 80 mm Hg before the procedure to 40 mm Hg after might be all that is needed for a good clinical result. This result is different from that in the young, active good surgical candidate with severe aortic stenosis who wants to return to vigorous activity. In this patient, a reduction in gradient from 80 to 40 mm Hg may not be enough to alleviate either the patient’s symptoms or the physician’s concerns about long-term outcome. The definition of success is arbitrary. One commonly used definition for successful aortic valve dilatation is a reduction in gradient by 50% or an improvement in aortic valve area by 25%. There are few published reports of what is actually obtained. In the recent multicenter French Registry experience, Cribier et al. [7] reported results in 442 patients. In this group, there was a reduction in the mean gradient from 78 f 29 to 37 k 19 mm Hg and improvement in the aortic valve area from 0.46 f 0.18 to 0.79 + 0.33 cm2. In some patients, such improvement has resulted in major improvement in left ventricular function and excellent clinical relief of symptoms. In a substantial number of patients, although dilatation is successful, significant residual stenosis of perhaps mild or even moderate degree remains. Whether this result will be associated with long-term clinical improvement is uncertain. For mitral stenosis, again the definition of success is arbitrary. In our institution, we attempt to achieve a final end-diastolic gradient of < 5 mm Hg and a mitral valve area of 2 1.5-2 cm2. This definition is based in part on what a surgical commissurotomy or valve replacement should achieve. In the young patient with isolated mitral stenosis, attempts should be made to achieve the optimal result rather than modest palliative improvement. Does Dilatation Result in Valvular Insufficiency? Concerns about the development of insufficiency are based on surgical experience in which mitral insufficiency developed in some patients undergoing mitral commissurotomy and aortic insufficiency developed in a significant number of
231
patients undergoing early attempted open aortic valve dilatation. In practice, these have not been major clinical problems. Currently, the procedure is restricted to patients with no or only mild insufficiency. In these patients, it is uncommon for significant insufficiency to develop. In some patients, a mild worsening of insufficiency may occur. Paradoxically, aortic insufficiency has actually decreased in some patients after dilatation. In these individuals, the calcific deposits presumably interfere with normal coaptation of the leaflets. Improved mobility of the leaflets after dilatation facilitates normal coaptation. What are the Long-Term
Benefits?
Follow-up data for these patients are accumulating but remain limited. Restenosis will be seen. It has been well documented in patients after surgical commissurotomy. Heger et al. [8] documented a 28% restenosis rate in 18 patients who underwent repeat evaluation at a mean of 12.2 years after successful mitral commissurotomy. Fortunately in patients with restenosis, repeat dilatation should be possible. For aortic stenosis, restenosis rates cannot be accurately estimated. If the mechanism of dilatation is merely fracture of calcific plates, rigidity and immobility might well return with time. The interval for this to take place is unknown. Fortunately, recurrence should also be amenable to repeat dilatation. Although much needs to be learned about the long-term benefits, in the shorter term significant clinical improvement has been seen, with relief of symptoms, decreased need for medications, and a low incidence of late procedure-related complications. In some patients with only a modest improvement in calculated aortic valve area, left ventricular function has improved greatly, an indication that a physiologically important improvement in orifice size has been effected.
Selection
Criteria
Current selection criteria are based on the admittedly limited experience achieved to date. For mitral stenosis, ideal patients are those who are candidates for commissurotomy because of isolated mitral stenosis with no or only mild mitral insufficiency, pliable leaflets, and calcification that is not severe. On the basis of the long surgical experience with commissurotomy in these patients, mitral balloon dilatation can be considered a treatment of choice in centers experienced with the technique. Exclusion criteria include other valvular heart disease or coronary artery disease requiring surgery, significant mitral insufficiency, left atria1 thrombi, substantial subvalvular-chordal fusion, and inexperience with the procedure. For the patient with a severely calcified mitral apparatus, the procedure can be done but the results may be less than ideal. For aortic stenosis, we currently restrict dilatation to three groups of patients. (1) Those who because of associated severe disease are not surgical candidates. The number of these patients will vary from center to center; however, in each center there will be patients in this category. (2) Those who are at high risk for surgery. Some of these patients will have associated diseases, others will be very elderly, and
232
others will have severely compromised left ventricular function. In some of these patients, the risk of surgery may range from 10 to 25% [9,10]. For this group, palliative aortic valve dilatation is also offered. (3) Those with severe aortic stenosis who are good surgical candidates but who decline aortic valve replacement. Dilatation can be offered as an alternative, and many such patients will accept it. Prior to the development of valvuloplasty, the only alternative to surgical therapy was medical therapy. This latter therapy is not satisfactory. We have reviewed the outcome in patients seen at our institution between 1978 and 1985, who had severe aortic stenosis but did not undergo aortic valve replacement. There were 46 patients with a mean age of 77.2 years. Actuarial survival at 1, 2 and 3 years was 56, 37, and 25%, respectively, compared to age-matched controls in whom the survival at the same time periods was 93, 85, and 77% [ll]. The very poor survival in this group of patients with medical therapy for severe aortic stenosis mandates the development of techniques such as valvuloplasty.
Conclusion Although aortic and mitral valve dilatation is rapidly emerging as a new percutaneous technique, the procedure is still in its infancy. The equipment requires considerable modification to improve the ease, efficacy, and safety of the procedure. For isolated mitral stenosis, this procedure should become the treatment of choice in carefully selected individuals. For aortic stenosis, it is only palliative at present. With this “4-minute-mile barrier” broken and the potential for modification of valvular stenoses by nonsurgical mechanical means demonstrated, newer and more effective treatment strategies should evolve.
References 1 Cribier A, Savin T, Saoudi N, Rocha P, Berland J, Letac B. Percutaneous transluminal valvuloplasty of acquired aortic stenosis in elderly patients: an alternative to valve replacement? Lancet 1986;1:63-67. 2 Lock JE, Khalilullah M, Shrivastava S, Bahl V, Keane JF. Percutaneous catheter commissurotomy in rheumatic mitral stenosis. N Engl J Med 1985;313:1515-1518. 3 McKay RG, Safian RD, Lock JE, et al. Balloon dilatation of calcific aortic stenosis in elderly patients: postmortem, intraoperative, and percutaneous valvuloplasty studies. Circulation 1986;74:119-125. 4 Palacios IF, Lock JE, Keane JF, Block PC. Percutaneous transvenous balloon valvotomy in a patient with severe calcific mitral stenosis. J Am Co11 Cardiol 1986;7:1416-1419. 5 McKay RG, Lock JE, Keane JF, Safian RD, Aroesty JM, Grossman W. Percutaneous mitral valvuloplasty in an adult patient with calcific rheumatic mitral stenosis. J Am Co11 Cardiol 1986;7:1410-1415. 6 Passik CS, Ackermann DM, Pluth JR, Edwards WD. Temporal changes in the causes of aortic stenosis: a surgical pathologic study of 646 cases. Mayo Clin Proc 1987;62:119-123. 7 Cribier A, Letac B, Lancelin B, et al. Percutaneous balloon valvuloplasty (PBV) for acquired aortic stenosis: preliminary immediate results of the French Registry (abstract). Circulation 1986;74(suppl 2):208. 8 Heger JJ, Warm LS, Weyman AE, Dillon JC, Feigenbaum H. Long-term changes in mitral valve area after successful mitral commissurotomy. Circulation 1979:59:443-448.
233 9 Smith N, McAnulty JH, Rahimtoola SH. Severe aortic stenosis with impaired left ventricular function and clinical heart failure: results of valve replacement. Circulation 1978;58:255-264, 10 O’Toole JD, Geiser EA, Reddy PS, Curtiss EI, Landfair RM. Effect of preoperative ejection fraction on survival and hemodynamic improvement following aortic valve replacement. Circulation 1978;58:1175-1184. 11 O’Keefe JH, Vlietstra RE, Holmes DR. Bailey KR. Natural history of candidates for balloon aortic valvuloplasty. J Am Co11 Cardiol 1987;9:195A.