Balloon dilation valvuloplasty of bioprosthetic valves in extracardiac conduits

Balloon dhtion valvul ty of bioprosthetic valves in extracardiac conduits Six patients, aged 8 to 20 years, with valved right ventricle to pulmonary artery conduits were catheterized for balloon dilation valvuloplasty of stenotic and calcified bioprosthetic valves. Conduit stenosis was severe in all cases, with peak-to-peak systolic pressure gradients of 82 to 100 mm Hg (mean 79 mm Hg) and right ventricular systolic pressures of 87 to 115 mm Hg (mean 100 mm Hg). Three patients had good results, with resldual peak-to-peak systolic pressure gradients of 20, 25, and 35 mm Hg. In two other patients, repeated balloon rupture before full inflation occurred, and residual gradients were high (55 and 80 mm Hg). One patient had substanttal proximal and distal conduit obstructton in addition to valvular stenosis, and balloon dtlation valvuloplasty was not attempted. No complicatkns occurred in five patients; one patient required iliac vein exploration to remove an avulsed balloon fragment. Baitoon dilation valvulop\asty can relieve bioprosthetic valve stenosis and postpone conduit replacement in some patients. (AM HEART J 1987;114:288.)

Thomas R. Lloyd, M.D.,* William J. Marvin, Ronald M. Lauer, M.D. Iowa City, Iowa

Jr., M.D., Larry T. Mahoney,

The extracardiac conduit operation pioneered by Rastelli et al.’ has permitted surgical correction of a number of forms of congenital heart disease, but the development of progressive conduit calcification and stenosis remains a serious and nearly universal late complication, especially for valved conduits.2-7 Bioprosthetic valve stenosis may increase the formation of obstructive peel and may also worsen obstruction at the proximal anastomosis by increasing the degree of right ventricular hypertrophy.2 If nonsurgical techniques could relieve the valve stenosis, the longevity of the conduit might be prolonged and fewer conduit replacements would be required in each patient’s lifetime. We report our experience with balloon dilation valvuloplasty in six patients with stenotic bioprosthetic valves in right ventricle to pulmonary artery conduits, which indicates that this technique can significantly relieve conduit valve stenosis. METHODS Patients. Six symptom-free patients, aged 8 to 20 years, were identified as candidates for balloon dilation valvulo-

From the University Received

Division of Pediatric Cardiology, of Iowa Hospitals and Clinics. for publication

Jan. 14, 1987; accepted

Reprint requests: William J. Marvin, Cardiology, Department of Pediatrics, Clinics, Iowa City, IA 52242. *Supported

268

by National

Department

Research

Feb.

of Pediatrics,

20, 1987.

Jr., M.D., Division of Pediatric University of Iowa Hospitals and

Service

Award

5T32H07413-08.

M.D., and

plasty (Table I). Candidates were required to have a total conduit peak-to-peak systolic pressure gradient of 50 mm Hg or greater across the conduit, as we and others* require for elective balloon dilation valvuloplasty of native pulmanic stenosis. Male and female patients were equally represented. All patients bad loud systolic murmurs, and five had conduit insufficiency murmurs of at least moderate intensity. Conduit calcification was evident on the chest roentgenogram in four patients and was noted on fluoroscopy in all. Right ventricular systolic pressure averaged 100 mm Hg, with a range of 87 to 115 mm Hg. These values were 72 % to 110 % of simultaneously measured aortic systolic pressure. Cineangiography demonstrated conduit stenosis and insticiency in all patients. Conduits and bioprosthetic valves. Four patients had typical right ventricle to pulmonary artery conduits. The repaired defect in three patients was complete transposition of the great arteries with ventricular septal defect and pulmonic stenosis. One patient bad pulmonic atresia with ventricular septal defect. The other two patients had modified right ventricle to pulmonary artery conduits. One patient, with absent pulmonic valve and tetralogy of Fallot, underwent resection of the pulmonic valve ring and interposition of a short conduit between the distal infundibulum and main pulmonary artery. The other patient had severe right ventricular failure after repair of tetralogy of Fallot, requiring enlargement of the outflow tract patch and insertion of a bioprosthetic valve in the pulmanic position. Four patients had glutaraldehyde-fixed porcine heterograft valves, and two patients had irradiated homograft valves. The valves were implanted 4 to 14 years before balloon dilation valvuloplasty (mean 9.3 years). All valves were 20 to 21 mm in diameter at the time of insertion.

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Table

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1. Candidates for balloon dilation valvuloplasty Patient

No.

Age

1 2 3 4 5 6

Sex

(yr)

Conduit

F M F F M M

8 15 17 16 20 9

Repaired

age (yr)

Conduit

defect

APV TOF PA TGA TGA TGA

5 11 10 12 14 4

APV = absent pulmonic valve in tetralogy of Fallot; TOF = tetralogy of Fallot; of the great arteries with ventricular septal defect and pulmonic stenosis.

Table

of

PA = pulmonic

atresia

valve

Porcine Porcine Porcine Homograft Homograft Porcine

with ventrioular

septal

defect;

TGA

= transposition

II. Hemodynamic data Peak-to-peak pressure gradient Patient

No.

Before

BDV

1

66

2 3 4 5 6

100

BDV = balloon dilation *BDV not performed.

systolic (mm Hg) After

% Ao = percentage

BDV

Before

20 35 25 60 55 -*

80 80 62 85 valwloplasty;

Right pressure

of simultaneously

Procedure. Valvuloplasty was performed under a protocol approved by the University of Iowa Human Subject Review Committee on March 1, 1984, and informed consent was obtained from the patients or their parents. Patients were lightly sedated with meperidine, promethazine, and chlorpromazine. In anticipation of sudden complication, a large peripheral venous cannula was inserted before valvuloplasty was attempted, cross-matched whole blood was in the laboratory during the procedure, and cardiac surgical and anesthesia staff were on standby. Percutaneous femoral arterial and venous catheterization was performed. After complete right- and left-sided heart catheterization with cineangiography, a No. 7 French end-hole catheter was positioned across the conduit and a No. 0.038 spring guide was placed through the catheter into the left or right pulmonary artery. The positioning catheter was then removed, and a soft extrusion balloon catheter was advanced over the spring guide. A balloon size 60% to 75% of the known valve diameter at the time of conduit insertion was arbitrarily selected for the initial dilation (12 to 15 mm). If dilation with this initial catheter was successful, dilation was repeated with an 18 mm balloon angioplasty catheter. This balloon size, 2 to 3 mm smaller than the original valve diameter, was selected to avoid dislodgement of intimal peel. Balloon inflations were brief (5 to 8 seconds) and were performed at inflation

87 115 110 90 90 110

measured

aortic

systolic

BDV 99 88 110 90 72 105

ventricular (mm Hg)

systolic (%Ao) (4%) After 40 50 50 70 90 -*

BDV 35 34 56 67 70

pressure.

pressures of 4 to 6 atm. Inflations were monitored fluoroscopically, and one to four inflations were performed at each balloon size until either complete inflation was achieved or the balloon ruptured. After balloon dilation valvuloplasty, right-sided heart pressure recordings and cineangiography were repeated. The patients were observed in the Pediatric Intensive Care Unit for a period of at least 4 hours and then overnight in the hospital. RESULTS Successful dilations. In three cases, balloon dilation valvuloplasty was considered successful (Table II). Patient 1 had a predilation conduit peak-topeak systolic pressure gradient of 66 mm Hg, all at the valve level. Dilation with a 15 mm balloon angioplasty catheter was uneventful. The 18 mm balloon catheter ruptured early during the second inflation. A second 18 mm balloon catheter also ruptured, but after complete inflation. The gradient was reduced to 20 mm Hg (Fig. l), and right ventricular systolic pressure was reduced to 40 mm Hg (35% systemic). Patient 2 had a predilation conduit gradient of 100 mm Hg, of which 80 mm Hg was at the valve

August1987

270

Lloyd et al.

American

Heart Journal

B

A

1, A and B. Pressure tracings in millimeters of mercury from patient 1 show pullback pressures from pulmonary artery (PA) to right ventricle (RV) and simultaneous aortic (AO) and right ventricular pressures. Panels A and B were recorded before balloon dilation valvuloplasty, and panels C and D were recorded after dilation.

Fig.

125 100

75 i

Fig.

1, C and D. See above for legend.

level and 20 mm Hg was distal to the valve. Initial dilation with a 12 mm balloon catheter was uneventful. After dilation with an 18 mm balloon catheter, the total conduit gradient was reduced to 35 mm Hg and right ventricular systolic pressure was 50 mm Hg (34% systemic). Patient 3 had a predilation conduit gradient of 80

mm Hg, of which 60 mm Hg was at the valve and 20 mm Hg was distal to the valve. Initial dilation with a 12 mm balloon catheter was uneventful. The 18 mm balloon catheter ruptured with complete inflation. After dilation the conduit gradient was reduced to 25 mm Hg and right ventricular systolic pressure was 50 mm Hg (56% systemic).

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2. Lateral cineangiographic frame from patient 4 shows maximum inflation of the balloon angioplasty catheter before balloon rupture. The bar shows the internal diameter of the conduit at insertion (22 mm), and the arrow indicates the site of balloon rupture. Note incomplete inflation of the balloon and marked calcification of the conduit.

Fig.

In all 3 cases the intensity of the systolic murmur diminished and the precordial thrill resolved. Increased conduit insufficiency was not apparent by either examination or cineangiography. Unsuccessful cases. Patient 4 had a predilation conduit peak-to-peak systolic pressure gradient of 80 mm Hg. It was not clear whether this gradient was primarily at the valve level or at the proximal anastomosis. Although a 22 mm conduit with a 20 mm valve had been implanted, the conduit measured only 10 to 15 mm in diameter by cineangiography. Extensive peel formation was evident, and the valve could not be clearly identified. Only partial inflation of 15 mm balloon catheters could be achieved because of repeated rupture of the balloons (Fig. 2). The conduit gradient was reduced to only 60 mm Hg and right ventricular pressure was 70 mm Hg (67% systemic). Patient 5 had a total predilation conduit gradient of 62 mm Hg, of which 25 mm Hg was at the proximal anastomosis, 32 mm Hg was at the valve, and 5 mm Hg was distal to the valve. Initial dilation with a 15 mm balloon catheter showed persistent narrowing at the proximal anastomosis, and the balloon ruptured on the second inflation. After

dilation the total conduit gradient was 55 mm Hg and right ventricular systolic pressure was 90 mm Hg (70% systemic). Patient 6 had a conduit gradient of 85 mm Hg, of which 20 mm Hg was at the proximal anastomosis, 40 mm Hg was at the valve, and 25 mm Hg was distal to the valve. Cineangiography suggested sternal compression of the proximal anastomotic site and peel formation in the proximal conduit. Because even an excellent valvuloplasty result would leave unacceptable residual gradients proximal and distal to the ,valve, balloon dilation valvuloplasty was considered unjustified and was not attempted. Elective conduit replacement has been performed on patients 4 and 6. Patient 5 is not considered an acceptable risk for elective surgery, remains symptom free, and is being followed medically. Comptications. Five patients had no adverse effects from the procedures and were discharged from the hospital the following morning. Patient 3 required iliac vein exploration to remove an avulsed balloon fragment. The balloon ruptured transversely, possibly as a result of surgical scar tissue, calcifications in the conduit, or a balloon fault (Fig. 3). On

272

Lloyd et al.

3. Balloon angioplasty catheter used in patient 3. The balloon ruptured transversely, and the distal fragment was avulsed from the catheter in the iliac vein during catheter withdrawal.

Fig.

4. A, Right femoroiliac venogram, anteroposterior projection. The filling defect marked by the arrow shows the location of the avulsed distal balloon fragment (patient 3). B, The fragment was surgically removed along with a large thrombus.

Fig.

through the dense scar tissue in presumably from five previous cardiac

catheter withdrawal

the groin, the distal balloon fragment catheterizations, inverted and was avulsed. The fragment was located by venography (Fig. 4) and surgically removed without incident. The patient was discharged 48 hours after the valvuloplasty.

DISCUSSION Goals of treatment. Balloon dilation valvuloplasty of native pulmonic valves is intended to provide lifelong relief of stenosis and obviate the need for surgery.s-lo One goal of ba.Uoon dilation valvuloplasty of bioprosthetic valves is to postpone the need for surgical conduit replacement. Because the number

Volume 114 Number 2

of surgical conduit replacements a patient will tolerate is not unlimited, by prolonging the viable lifespan of each conduit we may be able to extend the patient’s survival. Another goal would be the elimination of symptoms secondary to stenosis in a patient whose surgical risk is unacceptable. The factors that will determine the utility of this procedure are its initial rate of success in reducing conduit stenosis or symptoms to acceptable levels and the duration of that reduction. Initial success. Half of the patients had good hemodynamic results from balloon dilation valvuloplasty. We and others (Hellenbrand WE. Personal communication) have noted that the angiographic appearance of the bioprosthetic valve is little changed by balloon dilation. Both before and after dilation the valves appear fixed and immobile. Since to our knowledge, no pathologic specimens of conduit valves have been examined after balloon valvuloplasty, no structural correlations can be made with hemodynamic success or failure. Duration of benefit. The duration of benefit from balloon dilation valvuloplasty of bioprosthetic valves is unknown. Because calcific degeneration was well established in all our patients’ conduits, we speculate that the time to restenosis will be shorter than was the time to stenosis. Published series show that 20% to 30% of valved conduits required replacement within 5 years and that essentially all need replacement by 10 years.2-7 In this time frame a duration of benefit of even a few years would be important. Postponement of conduit replacement is particularly advantageous in the youngest children because the increased growth between operations should aid the surgeon in placing an optimum-sized conduit without intrathoracic compression. Limitations. Two factors that appeared to limit initial success in this series were balloon rupture and proximal conduit stenosis. Because the inflation pressures we used are those typically employed without rupture for dilation of native noncalcified pulmonic valves,8-10 balloon rupture was more likely the result of conduit calcifications. Although calcium deposits in the conduit peel should be covered with endothelium, they are interposed between the inflated balloon and the essentially undistensible conduit. Balloon dilation valvuloplasty was not successful in any of our patients with proximal conduit obstruction. These conduits seemed more heavily calcified with more peel formation, and repeated rupture of the angioplasty balloons before full inflation occurred. Even if this problem could be overcome, dilation may not necessarily relieve obstruc-

Balloon

dilation

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273

tion caused by peel formation or proximal anastomosis obstruction, nor would it be expected ‘to relieve sternal compression, all of which have been identified as key causes of conduit obstruction in some series.4-5 Although our efforts were focused on the relief of prosthetic valve stenosis, we noted that in two patients gradients of 20 mm Hg at the distal conduit anastomoses were eliminated by dilation. Based on this limited experience, we have not found distal obstruction to be a contraindication to balloon dilation valvuloplasty. Complications. Although balloon rupture is not a frequent occurrence in our experience with other lesions, more than half the balloon catheters used in this study ruptured. We attribute both the high incidence of balloon rupture and the occurrence of transverse rupture in our patient 3 to the presence of calcific degeneration. Transverse rupture is unusual. All other ruptured balloons in this series, and in our experience with other lesions, have torn longitudinally. Patients with extracardiac conduits may be expected to have had multiple previous cardiac catheterizations, with resultant formation of scar tissue in the groin. The complication of balloon fragment avulsion in the groin has not previously occurred in our experience with balloon dilation of various lesions. We believe the combination of scar and transverse rupture contributed to avulsion of the balloon fragment, even though the groin had been dilated to No. 12 French before insertion of the angioplasty catheter. Although removal of the fragment required a surgical procedure, the hospital stay was prolonged by only 24 hours. Conclusions. We have successfully dilated bioprosthetic conduit valves in three of six patients and postponed the need for conduit replacement. The additional risk, the optimal indications and timing, and the duration of benefit of this procedure have yet to be determined. If balloon dilation valvuloplasty can safely prolong the interval between conduit replacements, the longevity of patients with extracardiac conduits could be increased. Our initial experience demonstrates that patients whose conduit obstruction is primarily at the prosthetic valve level can have relief of stenosis from balloon dilation valvuloplasty and supports continued trial of this procedure. We gratefully acknowledge the assistance of Drs. H. Scott Baldwin, Jo& Camacho, G. Paul Matherne, and Armin J. Wagman in performing this investigation and the secretarial assistance of Mrs. Teresa Alberhasky and Kathy Dunlap in the preparation of this manuscript.

Lloyd

August IQ67 Americanmart .lournal

et al.

REFERENCES

1. Rastelli GC, Ongley repair of pulmonary artery fistula: report

6. Bisset GS, Schwartz DC, Benzilng G, Helmsworth 3, Schreiber JT, Kaplan S. Late results of reconstruction of the right ventricular outflow tract with porcine xenografts in children. Ann Thorac Surg 1981;31:437-43. 7. Ciaravella JM, McGoon DC, Danielson GK, Wallace RB, Mair DD. Experience with the extracardiac conduit. J Thorac Cardiovasc Surg 1979;78:920-30. 8. Rocchini AP, Kveselis DA, Crowley D, Dick M, Rosenthal A. Percutaneous balloon valvuloplasty for treatment of congenital pulmonary valvular stenosis in children. J Am Co11 Cardiol 1984;3:1005-12. 9. Kan JS, White RI Jr, Mitchell SE, Gardner TJ. Percutaneous balloon valvuloplasty: a new method for treating congenital pulmonary valve stenosis. N Engl J Med 1982;367:540-2. 10. Lababidi Z, Wu J. Percutaneous balloon valvuloplasty. Am J Cardiol 1983;52:560-2.

PA, Davis GD, Kirklin JW. Surgical valve atresia with coronary-pulmonary of a case. Mayo Clin Proc 1965;40:521-

n

2. howning TP, Danielson GK, Sch& HV, Puga FJ, Edwards WD, Driscoll DJ. Replacement of obstructed right ventricular-pulmonary arterial valved conduits with nonvalved conduits in children. Circulation 198%72(suDDl 2):84-7. 3. Jonas RA, Freed MD, Mayer JE, Cas&&da AR. Long-term follow-up of patients with synthetic right heart conduits. Circulation 1985;72(suppl 2):77-83. 4. Heck HA, Schieken RM, Lauer RM, Doty DB. Conduit repair for complex congenital heart disease-late follow-up. J Thorat Car&ovasc &rg 1978;75:806-14. 5. Kirklin JW, Bailey WW. Valved external conduits to pulmonary arteries. Ann Thorac Surg 1977;24:202-5.

R anstrip of left vea2rm mm on thresh&d far the i d : A co d study

to

Defibrillation results when a critical mass of myocardium is depolarized. The relationship between echocardlographlc determlnatlons of left ventricular mass, volume, and cavity radius to wall thickness ratio and deflbrlllatlon threshold for the Implantable deflbrlllator was examined. Ten patients with two large patch deflbrillatlng lead systems were studled. Deflbrillatlon threshold was determined lntraoperatlvely as the lowest energy termlnattng ventricular flbrlllatlon. Left ventricular mass, volume, and radius/posterior wall thickness ratio were calculated from two-dimensional echocardiograms. A significant correlation was found between left ventricular mass and deflbrlllatlon threshold (r = 0.78, p < 0.01). The correlations between thickness ratio defibrillation threshold and left ventricular volume (r = 0.59) and radius/wall (r = 0.55) were not significant. Subsequently, 11 dogs undwgolng deflbrillatlon trials with a tranevenous catheter and a chest wall patch were studled. Deflbrlllatlon threshold was defined as the lowest energy-terminating ventricular flbrlllation (four separate attempts). Subsequently, the heart was dissected, and the left ventricle (including the septum) was weighed. The correlation (p < 0.01). between left ventricular weight end deflbrlllaMon threshold (r = 0.76) was signlflcant We conclude that noninvaslve assessment of left ventricular mass and direct measurement of left ventricular weight are slgnttlcantly correlated with defibrillation threshold and consistent with the critical mass hypothesis. (AM HEART J 1987;114:274.)

Peter D. Chapman, M.D., Kiran B. Sagar, M.D., Jule N. Wetherbee, Paul J. Troup, M.D. Milwaukee, Wis.

From

the Division

Supported

in part

of Cardiology, Medical College of Wisconsin. by a grant from the American Heart Association

of

Wisconsin. Received Reprint Medical 53226.

274

for publication

Sept. 8, 1986; accepted

requests: Peter D. College of Wisconsin,

March

Chapman, M.D., Division 8700 W. Wisconsin Ave.,

2, 1987. of Cardiology, Milwaukee, WI

M.D., and

It appears that the success of ventricular defibrillation relates to the delivery of a current density for a su@cient period of time adequate to depolarize a critical mass of myocardium.’ Echocardiography has proved to be a reliable tool for noninvasive quantitation of left ventricular mass and vo1ume.2-4 The