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The Prolapsing Aortic Cusp: Experimental and Clinical Observations
NOTES
The Prolapsing Aortic Cusp Experimental and Clinical Observations Robert W. M. Frater, M.B., Ch.B.
T
he hitching up of a prolapsed aortic cusp has always seemed to the writer rather difficult to do really well. Although it is possible from a study of the normal valve to derive formulas for cusp dimensions that should ensure competent function [ 1, 21, these are not easy to apply in clinical situations and especially when the natural cusps are not equal in size. One certain fact is that in diastole the free edges of the cusps are in apposition. I t seems reasonable, therefore, that a system of reconstructing a cusp that ensures this relationship may also ensure competence. In order to test this hypothesis simple experiments were done using canine aortic valves.
MATERIALS A N D METHODS
Hearts were taken from dogs weighing 25 kg. or more that had been sacrificed for some other purpose. The aorta was cut through 1.5 cm. above the commissures. The left ventricular wall, the anterior cusp of the mitral valve, and the ventricular septum were cut 1 cm. below the points of the sinuses of Valsalva. Ten specimens of this valve containing portions of aorta and myocardium were suspended vertically. The aortic root was filled with water, and, provided that the specimen was used so that the valve was not distorted, the aortic valve was found to be competent in each case. In the first five experiments a Lucite tube 25 cm. long was tied into the aorta so that the column of water used to test competency of the valve was slightly greater than this. At these relatively low levels of pressure there was no apparent difference in competence when the valves were tested with this tall column of water and when they were tested with the short column obtained by merely filling the root of the aorta. Thereafter only the latter technique was used. No attempts were made to duplicate normal diastolic pressures. From the Department of Surgery, Albert Einstein College of Medicine, New York, N.Y. We thank Drs. A. Rudolph and J. Hoffman for referring the case and for their excellent studies. Accepted for publication Aug. 24, 1966.
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I, JAN.,
1967
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FIG. 1
FIG. 2
I n five specimens the coronary cusp was excised, after which the corpora Arantii' of the remaining cusps were precisely stitched together. A piece of pericardium was cut to the shape of a normal aortic cusp (Fig. 1). The distance from the right-sided commissures of the left and right coronary cusps to the corresponding corpora Arantii was measured with dividers ( X in Fig. 1). Lengths slightly greater than these were used for each half of the free edge of the pericardial cusp and, in turn, a still greater length for the depth of the cusp. The center point of the free edge of this cusp was stitched to the apposed corpora Arantii of the two remaining natural cusps (Fig. 2a). The outer ends were then stitched to the aortic wall at the commissures so that the free edges of pericardial and remaining natural cusps were exactly apposed. This was made easy by the stitches anchoring the midpoints of the cusps together. The base of the cusp was stitched in place by interrupted and running sutures, taking care that the body of the cusp remained quite smooth so as to exclude the possibility of distortion of the apposed free edge. The suture joining the midpoints of the cusps was finally removed and the competence tested as before. 'Giulio Cesare Aranzio (1530-1589), Professor of Anatomy at Bologna, described the corpora Arantii of the semilunar valves. These small elliptical nodules are set vertically in the exact middle of the contracting surfaces of the semilunar cusps. They fill the small triangular space that is present at the midpoints of the apposed cusps of the closed valve.
64
THE ANNALS OF THORACIC SURGERY
NOTE:
Prolapsing Aortic Cusp
In five other specimens a different procedure was followed in that the length of the free edge of the cusp was made several millimeters too long and no attempt was made to ensure apposition of the free edges in stitching it in place. This inevitably produced a prolapsing, incompetent cusp. In order to correct this, in three cases the center of this cusp was carefully stitched to the corpora Arantii of the remaining natural cusps (Fig. 2b). Tucks were then taken in the cusp at the commissure so as to regain complete apposition of the free edges of all the cusps. In two cases, the corpora Arantii were sutured together, and then each half of the free edge of the pericardial cusp was carefully lined up with the opposite natural cusp and stitched to it at the corpus Arantii. T h i s being done on each side, a fold was produced in the middle of the cusp (Fig. 2c). When this had been stitched together with mattress sutures the central anchoring stitches were removed and the valve tested for competence. RESULTS In the first five experiments, a competent valve was achieved in each case although a small trickle of insufficiency occurred at the central meeting point of the cusps where the absence of a corpus Arantii resulted in a very small defect. When in the remaining experiments the free edge of the pericardial cusp was made too long, incompetence was gross and obvious. With both techniques of repair the results were once again basically competent cusps with a small deficiency of contact in the center. DISCUSSION
These few simple experiments showed, within their obviously artificial conditions, that the basic premise that exact apposition of free edges would result in competent valves was correct. Given a clinical situation with a single prolapsing cusp it seemed reasonable to try one of the two techniques described above rather than the more usual one of trusting to the surgeon’s “eye.” Of the two techniques, that in which tucks are taken peripherally was probably a better one since it allowed reinforced mattress sutures to be used to secure the folds without running the risk of impairing cusp flexibility and mobility. Animal experiments in vivo were not tried since working on the intact dog’s aortic valve would have been infinitely more difficult and the results not easy to assess. It was, however, fully three years before the occasion arose to try the technique in a human case. CLINICAL EXAMPLE
T h e patient, a 9-year-old boy, had been followed for 3 years. He was known to have had a heart murmur since the age of 6. His only symptom was moderate exertional dyspnea. However, on physical examination, there were prominent carotid pulsations, a collapsing radial pulse, a blood pressure of 100/40-0 mm. Hg, and a heaving, thrusting apex beat in the fifth interspace 2 cm. outside the midclavicular line. A murmur of aortic insufficiency was audible over the VOL.
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NO. 1, JAN.,
1967
65
FRATER
whole precordium and maximal along the left sternal border. Over a period of 1 year chest roentgenograms showed increasing cardiac size apparently due to left ventricular enlargement. T h e electrocardiogram, however, was probably within normal limits for the patient’s age. Cineangiography was performed in the course of cardiac catheterization. Gross aortic insufficiency was seen, with all the insufficiency being in the region of the noncoronary cusp. In fact, it was thought that this might be an example of insufficiency occurring through the base of the noncoronary sinus of Valsalva. It was felt that valve replacement would be most undesirable in this child, but surgery was proposed with the expectation that this would not be necessary. At operation the left and right coronary cusps were rather small. At their common commissure these cusps were fenestrated, but were otherwise perfectly formed and met each other quite competently. T h e noncoronary cusp and sinus of Valsalva were enlarged. T h e free edge was greatly lengthened and hung down in the left ventricular outflow tract so that the cusp was almost inverted and quite functionless. There was no ventricular septa1 defect, and the subvalvular muscle was not hypertrophied. The corpora Arantii of the two normal cusps were sutured together with a 6-0 silk suture. A point on the free edge of the prolapsing cusp that seemed exactly opposite the corpora was stitched to them. There was no nodulus at this point. Folds were then taken in the free edge at each commissure and fastened by mattress sutures passed through the wall of the aorta (see Fig. 2b). In order to achieve perfect apposition of the leading edges, a large fold was taken at the left coronary commissure and a small one at the other. After this procedure the reformed cusp appeared to meet its opposite numbers completely except possibly for a point in the center where the absence of a nodulus left a small gap. The central stitch was removed before closing the aorta. Since operation, all peripheral evidence of aortic insufficiency has disappeared. T h e blood pressure is 100/70 mm. Hg. Ten months postoperatively a faint early diastolic murmur at the left sternal border can be heard. While there is, of course, no guarantee that this repair will last, it is evident that an initial success has been achieved by the technique described. It is true also that the same might have been achieved without using the trick of fastening the midpoints of the cusps together as a basis for ensuring precise apposition of the free edges. However, for the writer, it made the task easier; since another three years may pass before a similar case is met, it is presented now without waiting for further clinical experience. T h e technique is obviously applicable also to the replacement of single cusps. It is possible too that it might be used profitably in the insertion of aortic valve homografts. Primary joining of the corpora Arantii might make it easier to decide whether 66
THE ANNALS OF THORACIC SURGERY
NOTE:
Prolapsing Aortic Cusp
placement of the anchoring stitches is likely to draw the cusps apart or not. SUMMARY
Experimental observations on the creation and repair of aortic insufficiency by lengthening and shortening a single aortic cusp are described. T o ensure competence, the cusp with an excessively long free edge must have this dimension shortened so that it equals the free edges of the other cusps opposing it. This is made technically easier by temporarily fastening the midpoints of the cusps together. A clinical case of congenital aortic insufficiency in which this maneuver was tried is briefly presented. REFERENCES 1 . McGoon, D. C. Prosthetic reconstruction of the aortic valve. Mayo CZin. Proc. 30:88, 1961. 2. Frater, R. W. M. Unpublished data, 1962.
\OL.
3,
NO. 1, JAN.,
1967
67
The Prolapsing Aortic Cusp Experimental and Clinical Observations Robert W. M. Frater, M.B., Ch.B.
T
he hitching up of a prolapsed aortic cusp has always seemed to the writer rather difficult to do really well. Although it is possible from a study of the normal valve to derive formulas for cusp dimensions that should ensure competent function [ 1, 21, these are not easy to apply in clinical situations and especially when the natural cusps are not equal in size. One certain fact is that in diastole the free edges of the cusps are in apposition. I t seems reasonable, therefore, that a system of reconstructing a cusp that ensures this relationship may also ensure competence. In order to test this hypothesis simple experiments were done using canine aortic valves.
MATERIALS A N D METHODS
Hearts were taken from dogs weighing 25 kg. or more that had been sacrificed for some other purpose. The aorta was cut through 1.5 cm. above the commissures. The left ventricular wall, the anterior cusp of the mitral valve, and the ventricular septum were cut 1 cm. below the points of the sinuses of Valsalva. Ten specimens of this valve containing portions of aorta and myocardium were suspended vertically. The aortic root was filled with water, and, provided that the specimen was used so that the valve was not distorted, the aortic valve was found to be competent in each case. In the first five experiments a Lucite tube 25 cm. long was tied into the aorta so that the column of water used to test competency of the valve was slightly greater than this. At these relatively low levels of pressure there was no apparent difference in competence when the valves were tested with this tall column of water and when they were tested with the short column obtained by merely filling the root of the aorta. Thereafter only the latter technique was used. No attempts were made to duplicate normal diastolic pressures. From the Department of Surgery, Albert Einstein College of Medicine, New York, N.Y. We thank Drs. A. Rudolph and J. Hoffman for referring the case and for their excellent studies. Accepted for publication Aug. 24, 1966.
VOL.
3,
NO.
I, JAN.,
1967
63
FRATER
FIG. 1
FIG. 2
I n five specimens the coronary cusp was excised, after which the corpora Arantii' of the remaining cusps were precisely stitched together. A piece of pericardium was cut to the shape of a normal aortic cusp (Fig. 1). The distance from the right-sided commissures of the left and right coronary cusps to the corresponding corpora Arantii was measured with dividers ( X in Fig. 1). Lengths slightly greater than these were used for each half of the free edge of the pericardial cusp and, in turn, a still greater length for the depth of the cusp. The center point of the free edge of this cusp was stitched to the apposed corpora Arantii of the two remaining natural cusps (Fig. 2a). The outer ends were then stitched to the aortic wall at the commissures so that the free edges of pericardial and remaining natural cusps were exactly apposed. This was made easy by the stitches anchoring the midpoints of the cusps together. The base of the cusp was stitched in place by interrupted and running sutures, taking care that the body of the cusp remained quite smooth so as to exclude the possibility of distortion of the apposed free edge. The suture joining the midpoints of the cusps was finally removed and the competence tested as before. 'Giulio Cesare Aranzio (1530-1589), Professor of Anatomy at Bologna, described the corpora Arantii of the semilunar valves. These small elliptical nodules are set vertically in the exact middle of the contracting surfaces of the semilunar cusps. They fill the small triangular space that is present at the midpoints of the apposed cusps of the closed valve.
64
THE ANNALS OF THORACIC SURGERY
NOTE:
Prolapsing Aortic Cusp
In five other specimens a different procedure was followed in that the length of the free edge of the cusp was made several millimeters too long and no attempt was made to ensure apposition of the free edges in stitching it in place. This inevitably produced a prolapsing, incompetent cusp. In order to correct this, in three cases the center of this cusp was carefully stitched to the corpora Arantii of the remaining natural cusps (Fig. 2b). Tucks were then taken in the cusp at the commissure so as to regain complete apposition of the free edges of all the cusps. In two cases, the corpora Arantii were sutured together, and then each half of the free edge of the pericardial cusp was carefully lined up with the opposite natural cusp and stitched to it at the corpus Arantii. T h i s being done on each side, a fold was produced in the middle of the cusp (Fig. 2c). When this had been stitched together with mattress sutures the central anchoring stitches were removed and the valve tested for competence. RESULTS In the first five experiments, a competent valve was achieved in each case although a small trickle of insufficiency occurred at the central meeting point of the cusps where the absence of a corpus Arantii resulted in a very small defect. When in the remaining experiments the free edge of the pericardial cusp was made too long, incompetence was gross and obvious. With both techniques of repair the results were once again basically competent cusps with a small deficiency of contact in the center. DISCUSSION
These few simple experiments showed, within their obviously artificial conditions, that the basic premise that exact apposition of free edges would result in competent valves was correct. Given a clinical situation with a single prolapsing cusp it seemed reasonable to try one of the two techniques described above rather than the more usual one of trusting to the surgeon’s “eye.” Of the two techniques, that in which tucks are taken peripherally was probably a better one since it allowed reinforced mattress sutures to be used to secure the folds without running the risk of impairing cusp flexibility and mobility. Animal experiments in vivo were not tried since working on the intact dog’s aortic valve would have been infinitely more difficult and the results not easy to assess. It was, however, fully three years before the occasion arose to try the technique in a human case. CLINICAL EXAMPLE
T h e patient, a 9-year-old boy, had been followed for 3 years. He was known to have had a heart murmur since the age of 6. His only symptom was moderate exertional dyspnea. However, on physical examination, there were prominent carotid pulsations, a collapsing radial pulse, a blood pressure of 100/40-0 mm. Hg, and a heaving, thrusting apex beat in the fifth interspace 2 cm. outside the midclavicular line. A murmur of aortic insufficiency was audible over the VOL.
3,
NO. 1, JAN.,
1967
65
FRATER
whole precordium and maximal along the left sternal border. Over a period of 1 year chest roentgenograms showed increasing cardiac size apparently due to left ventricular enlargement. T h e electrocardiogram, however, was probably within normal limits for the patient’s age. Cineangiography was performed in the course of cardiac catheterization. Gross aortic insufficiency was seen, with all the insufficiency being in the region of the noncoronary cusp. In fact, it was thought that this might be an example of insufficiency occurring through the base of the noncoronary sinus of Valsalva. It was felt that valve replacement would be most undesirable in this child, but surgery was proposed with the expectation that this would not be necessary. At operation the left and right coronary cusps were rather small. At their common commissure these cusps were fenestrated, but were otherwise perfectly formed and met each other quite competently. T h e noncoronary cusp and sinus of Valsalva were enlarged. T h e free edge was greatly lengthened and hung down in the left ventricular outflow tract so that the cusp was almost inverted and quite functionless. There was no ventricular septa1 defect, and the subvalvular muscle was not hypertrophied. The corpora Arantii of the two normal cusps were sutured together with a 6-0 silk suture. A point on the free edge of the prolapsing cusp that seemed exactly opposite the corpora was stitched to them. There was no nodulus at this point. Folds were then taken in the free edge at each commissure and fastened by mattress sutures passed through the wall of the aorta (see Fig. 2b). In order to achieve perfect apposition of the leading edges, a large fold was taken at the left coronary commissure and a small one at the other. After this procedure the reformed cusp appeared to meet its opposite numbers completely except possibly for a point in the center where the absence of a nodulus left a small gap. The central stitch was removed before closing the aorta. Since operation, all peripheral evidence of aortic insufficiency has disappeared. T h e blood pressure is 100/70 mm. Hg. Ten months postoperatively a faint early diastolic murmur at the left sternal border can be heard. While there is, of course, no guarantee that this repair will last, it is evident that an initial success has been achieved by the technique described. It is true also that the same might have been achieved without using the trick of fastening the midpoints of the cusps together as a basis for ensuring precise apposition of the free edges. However, for the writer, it made the task easier; since another three years may pass before a similar case is met, it is presented now without waiting for further clinical experience. T h e technique is obviously applicable also to the replacement of single cusps. It is possible too that it might be used profitably in the insertion of aortic valve homografts. Primary joining of the corpora Arantii might make it easier to decide whether 66
THE ANNALS OF THORACIC SURGERY
NOTE:
Prolapsing Aortic Cusp
placement of the anchoring stitches is likely to draw the cusps apart or not. SUMMARY
Experimental observations on the creation and repair of aortic insufficiency by lengthening and shortening a single aortic cusp are described. T o ensure competence, the cusp with an excessively long free edge must have this dimension shortened so that it equals the free edges of the other cusps opposing it. This is made technically easier by temporarily fastening the midpoints of the cusps together. A clinical case of congenital aortic insufficiency in which this maneuver was tried is briefly presented. REFERENCES 1 . McGoon, D. C. Prosthetic reconstruction of the aortic valve. Mayo CZin. Proc. 30:88, 1961. 2. Frater, R. W. M. Unpublished data, 1962.
\OL.
3,
NO. 1, JAN.,
1967
67