Intermittent aortic regurgitation following aortic valve replacement with the Hall-Kaster prosthesis

Intermittent aortic regurgitation following aortic valve replacement with the Hall-Kaster prosthesis

J THORAC CARDIOVASC SURG 84:751-754, 1982 Intermittent aortic regurgitation following aortic valve replacement with the Hall-Kaster prosthesis Inte...

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J

THORAC CARDIOVASC SURG

84:751-754, 1982

Intermittent aortic regurgitation following aortic valve replacement with the Hall-Kaster prosthesis Intermittent aortic regurgitation (AR) was encountered in four of 160 consecutive patients subjected to aortic valve replacement (AVR) with the Hall-Kaster prosthesis. In all four cases, mechanical obstruction to the free movement of the occluder was carefully excluded. All cases were confirmed at reexploration of the valve. The major orifice of the valve was reorientated with correction of AR. A possible mechanism for this phenomenon is wide opening of the occluder beyond the axis of blood flow, resulting in nonclosure during diastole. Meticulous care should be taken in the orientation of this aortic prosthesis to avoid its opening beyond the axis offlow and resulting in postbypass AR.

Manuel J. Antunes, M.D., M.Med.(Wits), Peter R. Colsen, M.B., B.Ch., F.R.C.S.(Edin.) and Robin H. Kinsley, M.B., B.Ch., F.C.S.(S.A.), F.A.C.C., Johannesburg, South Africa

Mechanical dysfunction has been described with almost all types of prostheses. Incomplete ball movement and third orifice obstruction may occur with caged-ball prostheses.':" The occluder in disc valves may impinge on the ventricular or aortic wall or become jammed by interposition of chordae tendineae between the disc and the valve ring." Failure of BjorkShiley aortic valve closure has been described during heart-lung bypass in the presence of ventricular fibrillation." The Hall-Kaster prosthesis is a mechanical substitute valve of the tilting disc variety. The disc has a composite, two-part movement. The range of movement of the disc is wider than that of other prostheses and, in the aortic position, opens to 75 degrees. Although this wide opening enhances the hemodynamic function of the valve, we believe it significantly increases the prospects for mechanical dysfunction. This paper describes four cases of intermittent aortic

Table I. Clinical details Case

Indication for operation

2

Thrombotic obstruction of Bjork-Shiley prosthesis IE, AR Rheumatic; AS, AR Rheumatic; AS, AR

3 4

SizeofHall-Kaster prosthesis (mm)

Result

23

Died

23 29 25

Alive Alive Alive

Legend: IE, Infective endocarditis. AR, Aortic regurgitation. AS, Aortic stenosis.

regurgitation (AR) resulting from nonclosure of the disc. The probable mechanism and methods of prevention of this potentially catastrophic complication are discussed.

Patients and methods

Address for reprints: Professor Robin H. Kinsley, Division of Cardio-Thoracic Surgery, Medical School, University of the Witwatersrand, Hospital St., Johannesburg 200 I, Republic of South Africa.

Of 160 consecutive patients subjected to aortic valve replacement (AVR) with the Hall-Kaster prosthesis, four subjects had intermittent AR. The patients were 15, 21, 25, and 29 years of age. The indications for AVR are shown in Table I: thrombosed Bjork-Shiley prosthesis and infective endocarditis (one patient each) and rheumatic, mixed aortic valve disease (two patients). Isolated AVR was performed in one patient, whereas the remaining three patients had mitral valve procedures as well. Interrupted, figure-of-eight sutures were used for valve insertion. In the patient with a

© 1982 The C. V. Mosby Co.

751

From the Division of Cardio-Thoracic Surgery, University of the Witwatersrand, Johannesburg, Republic of South Africa. Received for publication Feb. 15, 1982. Accepted for publication March II, 1982.

0022-5223/82/110751+04$00.40/0

The Journal of

75 2 Antunes, Colsen, Kinsley

Thoracic and Cardiovascular Surgery

After disc reorientation, peak systolic postoperative pressure gradients of 5 and 15 nun Hg, respectively, were recorded in two patients. Of the four patients, one died of multiple organ failure several days after operation. The remaining three patients survived the hospital period and are alive at 19,9, and 5 months after operation, respectively. Discussion

Fig. 1. Position of the prosthesis. The orientation of the major orifice is indicated by the thick arrow. The thin arrow shows the relative position of the aortotomy. A. The initial position of the majororifice which was complicated by aortic regurgitation. Band C, The alternative and final positions which corrected aortic regurgitation. Ao, Aortotomy (thin arrow). LC, Left coronary. RC. Right coronary.

thrombosed Bjork-Shiley prosthesis, the aortic anulus was widened with pericardium and a size 23 nun Hall-Kaster prosthesis inserted obliquely by means of a technique previously described." In the remaining patients, valve sizes 23, 29, and 25 mm, respectively, were implanted. The valves were inserted in the plane of the aortic anulus. The orientation of the disc in the open position in each case can be inferred from the position of the major orifice (Fig. 1). In two cases, free AR was detected immediately after discontinuation of bypass. In another, it was diagnosed after approximation of the sternum, and in the fourth patient AR occurred a few hours after return to the intensive care unit. In all cases, AR was identified from the continuous systemic arterial pressure tracing, which showed a dramatic increase in the pulse pressure (Fig. 2). In all cases, cardiopulmonary bypass was reinstituted and the aorta reopened. Mechanical restriction of disc movement was excluded. The disc was then reorientated to an alternative position, as indicated in Fig. I. In Case 1 reorientation of the disc (position B) did not correct intermittent AR. A third position (C) corrected the problem.

In an attempt to improve hemodynamic performance, various modifications of the tilting disc prostheses have been developed. The Hall-Kaster valve has an ingenious mechanical design resulting in a 75 degree opening in a composite, two phase movement. As a result, hemodynamic performance of the prosthesis is probably superior to that of any other substitute valve. In an attempt to insert a valve larger than that which would normally be accommodated by the dimensions of the host aortic anulus, we have frequently widened the aortic anulus and inserted the valve obliquely. 7 However, this technique was used in only one of the four cases described in this paper. Aortic root enhancement and oblique insertion of the Bjork-Shiley aortic prosthesis have been performed in more than 50 patients in our unit, without malfunction. Indeed, we" believe the hemodynamic function of this valve may actually be improved by this technique. Recently, a similar technique has been employed with the St. Jude Medical prosthesis in the presence of a narrow aortic root. Our in vivo results have been confirmed by the experimental studies of Kasagi and Wada, 9 who demonstrated complete closure of the St. Jude Medical prosthesis regardless of its obliquity. We believe the mechanism of valve dysfunction relates to the position of the occluder in the open position, relative to the axis of blood flow. When the disc opens beyond the axis of flow, as shown in Fig. 3, A , closure probably is not possible. The initial retrograde aortic flow maintains the disc in the open position. The intermittent nature of the dysfunction is difficult to explain, but it is probably the result of nonlaminar flow with accompanying vortices producing intermittent closure. Alternatively, the disc may be critically positioned when fully opened, i.e., directly in the axis of flow. In each of the four patients described, reorientation of the valve away from the axis of flow corrected intermittent AR. However, in two cases it was apparent that the superior flow characteristics of the valve would be compromised (Fig. 3, B). This was confirmed by intraoperative pressure gradients across the valve of 5 and 15 mm Hg, respectively. Apart from jeopardizing hemodynamic function, reorientation of the disc may

Volume 84

A VR with Hall-Kaster prosthesis

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November. 1982

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Fig. 2. Typical radial artery pressure tracing. The pulse pressure increases dramatically because of nonclosure of the prosthetic disc. ECG . Electrocardiogram . RAD, Radial pressure.

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B Fig. 3. Proposed explanation for aortic regurgitation . A. The occluder opens beyond the axis of flow, making nonclosure probable . B. Rotation of the disc 180 degrees eliminates the problem but results in some impairment of the flow characteristics of the valve .

also create excessive turbulence with other possible complications, such as thromboembolism and coronary ostial stenoses . Obviously, oblique insertion of the prosthesis should be avoided. However, it is important to emphasize that in three of the four patients the valve was inserted in the normal plane of the host aortic anulus. Recently, a fifth patient was encountered in whom intermittent AR was noted on a routine outpatient visit

several months after the operation . Examination at that time revealed AR occurring in approximately 10 to 18 heartbeats per minute . The following day, no AR was detected, despite long periods of observation. It has therefore not been possible to document AR with pressure studies. The patient is well and it has been decided not to reoperate at this stage . Intermittent AR occurs in only a small percentage of patients following Hall-Kaster AVR (2.5% in our

The Journal of Thoracic and Cardiovascular Surgery

754 Antunes, Colsen, Kinsley

series). It is related to local, anatomic, and hemodynamic factors. It is disturbing that AR may be impossible to detect prior to closure of the aorta and discontinuation of cardiopulmonary bypass. Individual undefined factors may also be important. In one patient at least three positions were tested before a suitable disc orientation was obtained. When open, the disc should be orientated away from the axis of flow, but preferably not to a position in which there is significant aortic outflow obstruction. We believe the major orifice should face the anterior commissure, i.e., between the left and right aortic cusps. However, the position should be carefully evaluated in all patients and adjusted in each individual according to local anatomic factors. REFERENCES Hammermeister KE, Dillard DH, Kennedy JW: Severe intermittent mitral regurgitation in a Cross-Jones valve. Report of a case with angiographic and hemodynamic observations. J THoRAc CARDIOVASC SURG 58:575-580, 1969 2 Kalke B, Korns ME, Goott B, Lillehei CW, Edwards JE: Engagement of ventricular myocardium by open-cage at-

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rioventricular valvular prosthesis. J THORAC CARDIOVASC SURG 58:92-94, 1969 Shepherd RL, Glancy DL, Stinson EB, Roberts WC: Hemodynamic confirmation of obstruction to left ventricular inflow by a caged-ball prosthetic mitral valve. J THoRAc CARDIOVASC SURG 65:252-254, 1973 Behrendt DM, Austen WG: Current status of prosthetics for heart valve replacement. Prog Cardiovasc Dis 15:369401, 1973 Williams DB, Pluth JR, Orszulak TA: Extrinsic obstruction of the Bjork-Shiley valve in the mitral position. Ann Thorac Surg 32:58-62, 1981 Smith GH, Chandra K: Massive aortic incompetence associated with the Bjork-Shiley prosthesis. Thorax 28:627630, 1973 Kinsley RH: The narrow aortic annulus. A technique for inserting a larger prosthesis. Am Heart J 93:759-761, 1977 Kinsley RH: Valve prosthesis- patient mismatch. Circulation 59:418-419, 1979 Kasagi Y, Wada J: Hemodynamic characteristics of the St Jude Medical valve in mock circulation. Presented at the Second International Symposium on the St Jude Medical Prosthesis, San Diego, March, 1981