JACC Vol. 13. No. I 63 January 198Y:63-7

Aortic Regurgitation: A Common Complication After Surgery for Hypertrophic Obstructive Cardiomyopathy

ZION SASSON. MD, FACC, TIM PRIEUR, MD, YOANNA SKROBIK, MD, JOHN C. FULOP, MD,

WILLIAM G. WILLIAMS, MD, MARK A. HENDERSON, MD, CRIS GRESSER,

E. DOUGLAS WIGLE, MD, FACC, HARRY RAKOWSKI, MD

Surgical ventriculomyectomy and ventriculomyotomy by the aortic approach are safe and effective methods of relieving symptoms and obstruction to left ventricular outflow in patients with hypertrophic obstructive cardiomy- opathy. With the addition of Doppler ultrasound to the routine follow-up assessment of these patients an unexpect- edly high occurrence of aortic regurgitation was found in the postoperative patients. Because aortic regurgitation has been reported to rarely accompany this condition, 67 patients with hypertrophic obstructive cardiomyopathy were studied clinically and with Doppler echocardiography for the presence and severity of aortic regurgitation. Sever- ity of the regurgitation was quantitated by pulsed or color Doppler echocardiography according to the length and width of the regurgitant jet in at least two views.

In 37 patients with hypertrophic obstructive cardiomy- opathy who did not undergo surgery, aortic regurgitation

was detected in only 1 (3%) by Doppler ultrasound and in none clinically. In 52 patients who did undergo surgery and were studied a mean of 7.8 years postoperatively, aortic regurgitation of trivial to moderate degree was common, being detected in 28 (54%) by Doppler ultrasound and in 6 (12%) clinically. In a subgroup of 22 patients who were studied preoperatively and again early postoperatively (mean 6 weeks), new aortic regurgitation was found in 8 (36%) and was graded as trivial in ail.

Aortic regurgitation is a common complication related to ventriculomyectomy and ventriculomyotomy in patients with hypertrophic obstructive cardiomyopathy. Although initially trivial, the regurgitation may progress in severity over time. The regurgitation has been well tolerated in all patients studied to date.

(J Am Co11 Cardiol1989;13:63-7)

Symptomatic patients with hypertrophic obstructive cardio- myopathy may be treated medically with beta-adrenergic blockers, calcium entry blockers and/or disopyramide (1,2). Those patients who do not respond to or do not tolerate medical therapy may undergo a surgical ventriculomyect- omy procedure by the aortic approach (1,2). We have employed this procedure since 1961 (3) and. along with others, have found it to be extremely effective in relieving

From the Division of Cardiology, Toronto General Hospital, Toronto. Ontario. Canada. This study was supported in part by the Canadian Heart Foundation, Ottawa. Ontario and the Heart and Stroke Foundation of Ontario. Toronto. It was presented in part at the 58th Annual Scientific Session of the American Heart Association. Washington. D.C.. November 1985.

Aortic regurgitation has been previously reported to be an uncommon finding in patients with hypertrophic obstructive cardiomyopathy, both pre- and postoperatively (8-10). How- ever, since the addition of Doppler echocardiography to the routine follow-up assessment of these patients, we have found a disproportionately higher prevalence of postopera- tive aortic regurgitation in patients with hypertrophic cardio- myopathy. This prompted the reassessment of the preoper- ative and postoperative occurrence of aortic regurgitation in hypertrophic obstructive cardiomyopathy that forms the basis of this report.

Methods Manuxript received April 18, 1988: revised manuscript received August

3. 1988, accepted August 19, 1988. Address for rem-in&: Harry Rakowski, MD, Cardiology Division. Toronto

General Hospital, Eaton Building N. Room 12-212. X0 Elizabeth Street. Toronto. Ontario M5G X4. Canada

Study patients. The study group consisted of 67 patients with hypertrophic obstructive cardiomyopathy attending the hypertrophic cardiomyopathy clinic at the Toronto General Hospital. The diagnosis was established by echocardiog-

l>IYXY h? the Ame~-~c;rr~ College of Cardiology 0735.lOY7~89/$3.50

the symptoms and pressure gradient in both short- and long-term follow-up (4-7).

64 SASSON ET AL. JACC Vol. 13, No. I AORTIC REGURGITATION COMPLICATING SEPTAL MYECTOMY January 1989:63-7

Figure 1. Schematic representation of severity of aortic regurgita- tion (trivial [dotted area], mild [hatched area], moderate [cross- hatched area]) as determined by pulsed wave Doppler echocardio- graphic mapping in the apical five chamber view according to the length and width of the regurgitant jet. A0 = aorta; AV = aortic valve; LA = left atrium; LV = left ventricle; MV = mitral valve; RA zz right atrium; RV = right ventricle; TV = tricuspid valve.

raphy or cardiac catheterization, or both, according to previously published criteria (11-14). Each patient was as- sessed clinically and with Doppler echocardiography for the presence and severity of aortic regurgitation.

Of the 67 patients, 15 were studied only preoperatively, 30 were studied only postoperatively and 22 were studied preoperatively and again early postoperatively. Thus, a total of 37 patients were studied preoperatively and a total of 52 patients were studied postoperatively. The 52 patients stud- ied postoperatively were further subgrouped according to the operation performed. Ventriculomyotomy (15), the pro- cedure initially employed in this institution, had been per- formed on 12 of the 52 patients. At the time of this study this group had a mean age of 51 years and had been operated on a mean of 12 years earlier. Ventriculomyectomy (5-7). the procedure currently used in this institution, had been per- formed in 40 patients. At the time of study this group had a mean age of 47 years and had been operated on a mean of 6 years earlier.

Clinical and Doppler echocardiographic assessment of aor- tic regurgitation. The presence of aortic regurgitation was assessed clinically in all patients by at least two experienced cardiologists. It was diagnosed when an early diastolic blowing murmur was heard with careful auscultation in a quiet room and was assessed as mild, moderate or severe according to the intensity and duration of the murmur as well as associated peripheral signs (16).

A continuous and pulsed wave Doppler echocardio- graphic study, and, when available, a Doppler color study, was performed in each patient using commercially available ultrasound equipment (Hewlett-Packard 77020A, Advanced Technology Laboratories [ATL] Mark 600. Ultramark 6 or

Table 1. Presence and Severity of Doppler-Detected Aortic Regurgitation in the 52 Patients Studied Postoperatively

Patients None

Myectomy (n = 40) 21 (53%) Myotomy (n = 12) 3 (25%)

Trivial

11 (28%) 3 (25%)

Mild

7 (18%) 3 (25%)

Moderate

I ( 3%) 3 (25%)

Ultramark 8). Aortic regurgitation was considered to be present when two experienced observers agreed that the spectral or Doppler color recording displayed a retrograde holodiastolic, turbulent, high velocity flow signal in the subaortic area. Severity of the aortic regurgitation was quantitated by Doppler recording in at least two standard apical views according to the length and width of the regurgitant jet (Fig. 1 and 2), as defined by the consensus opinion of the two observers.

Left ventricular end-diastolic and end-systolic inter4 dimensions were obtained with two-dimensional-guided M- mode echocardiography across the minor axis in the stan- dard parasternal long-axis view.

Statistical analysis. The results of aortic regurgitation are reported as proportions (percentages) of the positive findings in each group and are statistically compared by chi-square analysis. Left ventricular internal dimensions are reported as mean 2 1 SD and compared by the unpaired Student’s t test.

Results Preoperative patients. None of the 37 patients studied

preoperatively had aortic regurgitation on clinical evaluation and only I (3%) had aortic regurgitation graded as mild by Doppler examination.

Postoperative patients. Six (12%) of the 52 patients stud- ied postoperatively had aortic regurgitation on clinical ex- amination, whereas 28 (547~) had aortic regurgitation by Doppler examination (p < 0.01 compared with the preoper- ative group).

The severity of aortic regurgitution and the correlation between clinical and Doppler-detected aortic regurgitation are shown in Fig. 3. Trivial aortic regurgitation by Doppler ultrasound was not detected clinically in any patient. Aortic regurgitation was detected clinically in 3 of 10 patients with mild and in 3 of 4 patients with moderate aortic regurgitation as graded by Doppler ultrasound. The severity of aortic regurgitation was clinically graded as mild in each of the six patients in whom it was detected.

Table 1 compares the results in the patients who under- Hsent ventricrrlomyotomy versus those who underwent ven- triculomyectomy. There was a trend toward a higher preva- lence and a more severe degree of aortic regurgitation in the group with ventriculomyotomy, but this did not reach sta- tistical significance. Because the surgical approach is iden-

JACC Vol. 13, No. I January lY89:63-7

SASSON ET AL. AORTIC REGURGITATION COMPLICATING SEPTAL MYECTOMY

65

tical in the two procedures, this trend is likely related to the mained within the normal limits in all patients. The aortic longer duration of postoperative follow-up in the ventricu- regurgitation has been well tolerated and has not required lomyotomy group. any specific medical or surgical intervention to date.

Table 2 lists the findings in the subset of 22 patients studied both preoperatively and again early (mean of 6 weeks) postoperatively. Preoperatively, only one patient had aortic regurgitation (trivial) by Doppler ultrasound and this was not detected clinically. Postoperatively, 8 patients were found to have new aortic regurgitation by Doppler ultrasound. It was graded as trivial in all, and in none was the aortic regurgitation detected clinically.

One patient with a moderate degree of aortic regurgitation by Doppler examination 5 years after ventriculomyectomy recently underwent a repeat ventriculomyectomy for persist- ent symptoms and severe obstruction to left ventricular outflow. At surgery, the aortic valve appeared thickened and deformed with curling of the cusp edges and was thus replaced with a prosthetic valve.

In all but one patient the aortic valve apparatus as well as the aortic root appeared normal on two-dimensional echo- cardiography. In all patients operated on, the aortic valve at the time of initial surgery was described as normal. Further- more. the left ventricular chamber dimensions have re-

Left ventricular dimensions. Left ventricular end- diastolic dimensions were similar in the preoperative and the postoperative groups (44.5 i 3.8 versus 46.3 t 6.5 mm, respectively; p = NS). Left ventricular end-systolic dimen- sions were also similar in the two groups (29.5 2 6.5 versus 29.8 1- 8.7 mm, respectively; p = NS). Further analysis of left ventricular dimensions in the postoperative patients, subgrouped according to the presence or absence of aortic regurgitation, failed to demonstrate any significant differ- ences.

Figure 3. Correlation of Doppler-detected and clinically-detected aortic regurgitation (AR) in the 52 patients postoperatively. In all six patients in whom an early diastolic murmur was heard, the regurgi- tation was clinically graded as mild (see text).

ON0 AR a Doppler Detected AR 61 Clinical AR

0 NONE TRIVIAL MILD MODERATE

Figure 2. Early diastolic Doppler color stop frame in the apical long-axis view recorded from a patient with hy- pertrophic cardiomyopathy and aortic regurgitation 5 years after successful ventriculomyectomy. Left, Two-di- mensional echocardiogram during iso- volumic relaxation demonstrating the aortic (straight arrow) and mitral valves in the closed position. The aor- tic valve appears normal. Right, Super- imposed Doppler color recording dem- onstrating the mosaic pattern of a turbulent flow velocity (curved arrow) across the left ventricular (LV) outflow tract in keeping with aortic regurgita- tion of moderate severity. LA = left atrium.

Table 2. Aortic Regurgitation Pre- and Early Postoperatively by Doppler Study in 22 Patients

Patients None Trivial Mild Moderate

Preop !I I 0 0 Postop 14 x* 0 0

‘p < 0.01 for development of new aortic regurgitation postoperatively (pwtop). Preop = preoperdtively.

66 SASSON ET AL. JACC Vol. 13, No. 1 AORTIC REGURGITATION COMPLICATING SEPTAL MYECTOMY January 1989:63-7

Discussion New aortic regurgitation after surgery for hypertrophic

obstructive cardiomyopathy. Our study has demonstrated that aortic regurgitation of varying degrees is frequently found after ventriculomyectomy or myotomy in patients with hypertrophic cardiomyopathy. Furthermore, it has es- tablished a clear relation between the occurrence of aortic regurgitation and this procedure, suggesting cause and ef- fect. Aortic regurgitation assessed either clinically or with Doppler ultrasound was an uncommon finding in these patients preoperatively. Postoperatively, it was commonly detected by Doppler ultrasound but usually not suspected on clinical grounds (Fig. 3). This greater sensitivity of Doppler ultrasound compared with the clinical examination in detect- ing aortic regurgitation may well explain why previous reports, published before the routine use of Doppler echo- cardiography, indicated that aortic regurgitation was uncom- mon in these patients both before and after operation.

In the subgroup of 22 patients studied preoperatively and again early (mean 6 weeks) postoperatively, 8 (36%) devel- oped new aortic regurgitation postoperatively. The regurgi- tation was only trivial in severity in this early postoperative group, suggesting that a longer follow-up period is required to determine whether more significant (mild or moderate) degrees of aortic regurgitation will develop.

Possible pathogenetic mechanisms. The etiology of the aortic regurgitation is unclear. Because the operation is performed with an aortotomy and through the aortic valve, leaflet trauma at the time of surgery could well render the aortic valve incompetent. The normal appearance of the aortic valve on echocardiographic studies may be explained by trauma that is likely to be only minor and therefore beyond the resolution of the two-dimensional echocardio- gram. The one patient who underwent two ventriculomyect- omy procedures had moderate aortic regurgitation after the first procedure. At the time of the second procedure, the aortic valve appeared normal on the two-dimensional echo- cardiographic study but at operation it was described as mildly fibrosed with thickening and curling of the cusp edges. This may represent independent aortic valve disease or the result of previous aortic valve trauma at the initial operation 5 years previously. This may also explain why more significant degrees of aortic regurgitation are only seen later postoperatively as tissue reaction to minor leaflet trauma and its subsequent hemodynamic effects progress over time. However, because such data are not available on other patients, this explanation remains only speculative.

Alternatively, the subvalvular incision may result in some loss of subvalvular support or focal fibrosis with slight distortion of the anulus, enough to result in aortic regurgita- tion with a normal-appearing aortic valve on echocardiog- raphy. We were not able to define differences in subvalvular

anatomy in patients with or without postoperative aortic regurgitation.

A third possibility may relate to the altered velocity, direction and dynamics of the turbulent jet of blood in the outflow tract after surgery. The various changes in flow characteristics may adversly affect the aortic valve and render it incompetent as a result of recurrent trauma to the valve during ventricular ejection. This may be particularly relevant in patients with an incomplete myectomy who are left with a mild residual pressure gradient due to eccentric systolic anterior motion of the mitral valve leaflets (17).

Clinical implications. The presence of aortic regurgitation argues for the continued postoperative use of endocarditis prophylaxis in patients with hypertrophic obstructive cardio- myopathy. It is encouraging that, despite a relatively long period of follow-up, no patient has yet developed significant chamber enlargement or other specific complications related to the aortic regurgitation. However, because the potential for complications exists, it seems appropriate to follow-up these patients with periodic two-dimensional and Doppler echocardiographic examinations. Specific attention should be paid to chamber dimensions and severity of aortic regur- gitation to establish the natural history of this condition.

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