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Ann Thorac Surg 2000;69:135-139
© 2000 The Society of Thoracic Surgeons

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Original Articles

Intraoperative echocardiographic detection of regurgitant jets after valve replacement

^a Cardiovascular Imaging Center, Department of Cardiology, The Cleveland Clinic Foundation, Cleveland, Ohio, USA
^b Cardiovascular Imaging Center, Department of Thoracic and Cardiovascular Surgery, The Cleveland Clinic Foundation, Cleveland, Ohio, USA

Address reprint requests to Dr Thomas, Department of Cardiology, Desk F15, The Cleveland Clinic Foundation, 9500 Euclid Ave, OH 44195;
e-mail: thomasj{at}ccf.org

	Abstract

Top Abstract Introduction Patients and methods Results Discussion References

 
Background. Paravalvular jets, documented by intraoperative transesophageal echocardiography, have prompted immediate valve explantation by others, yet the significance of these jets is unknown.

Methods. Twenty-seven patients had intraoperative transesophageal two-dimensional color Doppler echocardiography, performed to assess the number and area of regurgitant jets after valve replacement, before and after protamine. Patients were grouped by first time versus redo operation, valve position and type.

Results. Before protamine, 55 jets were identified (2.04 ± 1.4 per patient) versus 29 jets after (1.07 ± 1.2 per patient, p = 0.0002). Total jet area improved from 2.0 ± 2.2 cm² to 0.86 ± 1.7 cm² with protamine (p < 0.0001). In all patients jet area decreased (average decrease, 70.7% ± 27.0%). First time and redo operations had similar improvements in jet number and area (both p > 0.6). Furthermore, mitral and mechanical valves each had more jets and overall greater jet area when compared to aortic and tissue valves, respectively.

Conclusions. Following valve replacement, multiple jets are detected by intraoperative transesophageal echocardiography. They are more common and larger in the mitral position and with mechanical valves. Improvement occurs with reversal of anticoagulation.

	Introduction

Top Abstract Introduction Patients and methods Results Discussion References

 
Transesophageal echocardiography (TEE) is very effective in detecting paravalvular leaks [1], with asymptomatic paravalvular leaks reported to exist in over 30% of patients following elective initial mitral valve replacement [2]. Although severe leaks, greater than 3 cm², are often repaired at the time of operation, the management of mild or moderate leaks is controversial. In a large study of Bjork-Shiley and St. Jude mechanical valves, paravalvular leaks were the cause of reoperation in 2.2% of over 1,000 mitral and aortic valves [3]. Because of the known risks for clinical deterioration and the theoretical risks for endocarditis and embolic complications, it has been advocated that even mild paravalvular leaks, defined by total jet area on TEE < 3 cm², should be repaired [4]. In addition, leaks found at the time of operation by intraoperative TEE have prompted some to perform immediate or perioperative valve replacement, often exposing patients to the risks of prolonged cardiopulmonary bypass and operative times, and occasionally a second median sternotomy. Though intraoperative TEE is commonly used, most are performed following weaning from cardiopulmonary bypass, but before reversal of systemic anticoagulation with protamine (in case further operative revision is required). We hypothesized that, although paravalvular jets are common, they improve with restoration of normal coagulation parameters and that trivial jets are of minimal clinical significance in the early postoperative period.

	Patients and methods

Top Abstract Introduction Patients and methods Results Discussion References

 
A total of 27 patients, 18 men and 9 women, with aortic or mitral valve diseases, undergoing valve replacement at the Cleveland Clinic Foundation, were randomly selected for evaluation. The age of the patients ranged from 33 to 86 years (68.4 ± 11.6 years). All patients underwent routine intraoperative TEE to evaluate both postbypass cardiovascular function and valvular structural integrity. All valves were implanted using standard techniques and included nonabsorbable pledgetted mattress sutures for both mitral and aortic valves. All patients, except 2, were given intravenous -aminocaproic acid (Amicar; American Regent Laboratories Inc, Shirley NY; 10g bolus with 1 g/hour continuous infusion) and all received routine systemic heparinization before initiation of cardiopulmonary bypass. After successful weaning from extracorporeal support, heparin was reversed with protamine sulfate as appropriate for weight and baseline activated clotting time (ACT).

Echocardiography
Multiplane TEE imaging was performed using HP 2000 or 2500 (Hewlett-Packard, Andover, MA) with 5 MHz transducers after the surgical replacement of either the mechanical or tissue valves. TEE imaging was performed before and after protamine infusion as a component of the routine assessment of hemodynamic and structural conditions. For aortic valves, imaging started with a short axis view (45 to 70 degrees) of the aorta to look for aortic regurgitant jets. The multiplane TEE imaging angles were rotated from 0 to 180 degrees. The long axis views of the aorta (120 to 145 degrees) were carefully imaged to maximize the regurgitant jets, if any, for later measurement of the number of the jets and the total area of the regurgitant jets. For mitral valves, the TEE imaging was oriented from 0 to 180 degrees, especially at 0, 45, 90, and 135 degrees for offline analysis for counting the number and area measurement of the jets. A single cardiologist and experienced sonographer, both with special training in intraoperative echocardiography (A.J.M. and T.S.), subsequently reviewed all intraoperative studies, at which time the total number of jets and the total area of jets were determined. Follow-up transthoracic echocardiography (TTE) was performed as per routine postcardiac valve operation before discharge. All TTEs were interpreted by board certified cardiologists with special training in echocardiography, and were blinded to the intraoperative findings and the goals of this study. Questionable or positive TTE findings were reviewed for accuracy by a single observer (T.S.) blinded to the original findings.

All statistics were performed using Student’s t test with paired testing when appropriate. A p value less than 0.05 was considered statistically significant.

	Results

Top Abstract Introduction Patients and methods Results Discussion References

 
Twenty-seven patients, 18 men and 9 women, underwent 28 valve replacements. Twelve valves were placed in the aortic position, of which 2 were mechanical (St. Jude Medical, St. Paul, MN) and 10 were bioprosthetic (Carpentier-Edwards, Baxter International, Deerfield, IL). Sixteen valves were in the mitral position with 11 bovine tissue (Carpentier-Edwards) and 5 mechanical (St. Jude Medical). One patient underwent combined mitral and aortic valve replacement. Of the 27 patients, 17 had replacement of their native valves, whereas the remaining 10 underwent replacement of previously repaired or replaced valves. ACT at the time of initial TEE evaluation was 545 ± 127 seconds (range, 339 seconds to more than 15 minutes). Mean ACT following protamine was 137 ± 23.7 seconds (range, 101 to 225 seconds). Postprotamine ACTs were not available in 2 patients, both of whom were judged to have received an appropriate dose of protamine up on review of their intraoperative medication records.

For the entire population, 55 paravalvular jets were identified (mean 2.04 ± 1.4 jets per patient) before heparin reversal with protamine. No significant hemodynamic changes or major interventions occurred between serial TEEs. Following protamine, 29 jets were identified (1.07 ± 1.2 per patient, p = 0.0002). Total color Doppler imaged jet area before protamine significantly decreased from 2.0 ± 2.2 cm² to 0.86 ± 1.7 cm² after protamine (Fig 1, p < 0.0001). Seven patients had no change in the number of jets with the remainder having a significant decrease in the number of jets from 2.6 ± 0.9 to 1.4 ± 1.2 (p = 0.0001). All patients demonstrated a net decrease in jet area. The average decrease in jet area was 70.7% ± 27.0% (range, 7.3% to 100%) with 6 patients having no evidence of paravalvular jets after protamine. Proximal flow convergence was not observed in any jet, implying a regurgitant orifice area of less than 0.01 cm². No patient required immediate reexploration for valve or suture ring-related problems. No patient required reoperation for delayed valve or paravalvular-related regurgitation or complications. Overall, trivial paravalvular jets were common before the reversal of heparin-induced anticoagulation, but following protamine administration the number and the area of jets decreased significantly, and were felt to be of no clinical significance. Two patients had total jets areas greater than 3 cm² (4.8 and 7.6 cm² each) following protamine and both had uncomplicated postoperative courses. The 2 patients not administered intraoperative Amicar had no jets following protamine.

View larger version (87K): [in this window] [in a new window]   Fig 1. Intraoperative TEE of a mitral prosthesis imaged in the 0 degree plane demonstrating 3 jets (A) before and 1 jet (B) after protamine. The mitral sewing ring is identified. An aortic prosthesis imaged in the 130 degree plane demonstrating 3 jets (C) before and 1 jet (D) after protamine (LA = left atrium; LV = left ventricle).

Aortic versus mitral valves
In addition, the changes in paravalvular jet characteristics between aortic and mitral valves were also compared. When compared to mitral valves, aortic valves had less paravalvular jets per patient before (0.91 ± 1.1 versus 2.8 ± 0.9, p = 0.0002) and after (0.45 ± 0.7 versus 1.5 ± 1.3, p = 0.013) protamine. A similar trend was observed for the area of jets before (aortic, 0.74 ± 1.0 versus mitral, 2.9 ± 2.4, p = 0.004) and after (aortic, 0.227 ± 0.4 versus mitral, 1.3 ± 2.1, p = 0.065) protamine (Fig 2). Despite the greater number and area of jets for mitral valves compared to aortic valves, the percent decrease in valve area was similar for both valve positions (aortic, 67.4 ± 20.3 versus mitral, 71.7 ± 29.3, p = 0.72).

View larger version (19K): [in this window] [in a new window]   Fig 2. Changes in total valve jet area, pre and postprotamine administration, for (A) aortic and (B) mitral valves. Dashed lines represent tissue valves and solid lines represent mechanical valves. Dark solid line represents average for all valves in that position.

Follow-up evaluation
Routine postoperative predischarge transthoracic echocardiographic examination was performed in 25 of 27 patients (93%, range 3 to 8 days postoperation). Of the mitral valves, 15 of 16 (93.8%) had no echocardiographic evidence of regurgitation or paravalvular leaks. A single patient with a tissue valve had trivial central mitral regurgitation, but no paravalvular jets. One patient did not have a predischarge exam performed, was discharged following an uncomplicated postoperative course, and is reported to be doing well 4 months postoperatively. One patient developed a postoperative mitral leaflet thrombus, but did not have any echocardiographic evidence of valvular or paravalvular regurgitation. The two patients with greater than 4.5 cm² intraoperative jet areas had no evidence of valvular or paravalvular regurgitation on their predischarge TTE.

For aortic valves, 11 of 12 (91.7%) patients underwent routine postoperative, predischarge transthoracic echocardiographic evaluation. Eight had no evidence of valvular insufficiency. Two patients had mild and 1 had trivial aortic insufficiency, with all patients having central jets and no evidence of paravalvular regurgitation. All 3 had tissue valves. Of the 3 patients with postoperative aortic insufficiency on TTE, the 2 patients with mild central jets had each only a single, small area (< 0.5 cm²) paravalvular jet postprotamine. The third patient had no intraoperative jets detected after protamine. The 1 patient who did not have a routine postoperative study is reported to be doing well 3 months after discharge.

	Discussion

Top Abstract Introduction Patients and methods Results Discussion References

 
The concern for worsening of paravalvular regurgitation and clinical deterioration has prompted an aggressive, though unproved, response when these jets are identified by intraoperative TEE [1, 2, 4]. As we have demonstrated, paravalvular regurgitation is common after elective valve operation, but the number and size of these jets decrease significantly after reversal of systemic anticoagulation with protamine sulfate, and any residual jets were undetectable on predischarge follow-up TTE. Although, TTE is not as sensitive in detecting paravalvular leaks, particularly in the mitral position, the absence of any detectable jets is none the less clinically significant. We speculate that with restoration of normal hemostatic mechanisms, as defined by a return to normal activated clotting times, that small leaks become plugged with platelet and thrombin aggregates. We have also shown that the incidence and response to protamine is similar between primary and redo valve operations. In addition, the larger number and area of jets with mitral valves may be related to the increased technical ability to detect mitral versus aortic jets by TEE, and is of little clinical significance, particularly in light of the dramatic improvements observed.

The observation of the increased number and area of jets for mechanical versus tissue valves is limited by the small number of total mechanical valves in our patient population (n = 7), and should be validated by further studies. Although, with mechanical valves there may be a greater number of trivial intraprosthetic jets, secondary to the hinged designed, these are often difficult to distinguish from true paravalvular leaks. In addition, mechanical valves often have a trivial amount of inherent regurgitation associated with them. This is commonly considered closure regurgitation, and although the overall clinical significance is unknown, this small amount of regurgitation is believed to reduce the risk of thrombus formation. Nevertheless, although mechanical valves had similar improvements in jet areas with protamine and on follow-up TTE, the blinded reviewers did not comment on the presence of any significant closure regurgitation. Therefore, we feel that our findings can serve as guidelines for the intraoperative evaluation of patients following mechanical valve replacement.

Though repair or replacement of moderate and large paravalvular leaks, either from technical or anatomical causes, should be considered, the 2 patients in our series with moderate leaks had no postoperative jets. The fact that all of our jets areas improved with restoration of normal hemostatis and no postoperative paravalvular leaks were detected, should prompt a conservative approach when mild jets are encountered after weaning from cardiopulmonary bypass. Though not observed inour experience, jet areas that do not improve with restoration of normal hemostatis and that are greater than 3 cm² should raise suspicion. Transesophageal or transthoracic echocardiographic quantification of paravalvular regurgitation using other methods, such as proximal flow convergence, should be used in such cases [5–7].

Clinical observations suggest that the majority of these physiologic jets arise at the commissural level of the valvular stents. In vitro studies have confirmed these observations along with documenting minimal intrinsic paravalvular leaks associated with mechanical valves (< 1.7 cm³/beat) [8]. This helps to explain the significantly greater area and number of jets observed with mechanical valves. Though the multiplane TEE imaging supports this, the exact location of the origins of these jets is difficult to define. With further refinements in 3-dimensional color Doppler systems, these questions can be further addressed. In addition, studies that evaluate the timecourse resolution of paravalvular leaks, such as after chest closure or postoperative TEE evaluation in the intensive care units may provide further insight and potentially alter the surgical approach.

Paravalvular jets are common following valve replacement operation, but they improve overall with better hemostasis. Primary and repeat valve operations both demonstrated similar improvements in jet characteristics. Though mitral and mechanical valves had more and a greater area of jets, these findings may be related to the technical imaging factors and the design characteristics of the valves. No early valve related complications occurred despite residual regurgitant paravalvular jets, and most regurgitation was resolved before discharge.

	Acknowledgments

 
Supported in part by Grant 93-13880 from the American Heart Association, Greenfield, TX, Grant 1R01HL56688-01A1 from the National Heart Lung and Blood Institute, Bethesda, MD, Grant NCC9-60 from the National Aeronautics and Space Administration, Houston, TX, and Grant-in-aid #NEO-97-225-BGIA from the American Heart Association, Northeast Ohio Affiliate.

	References

Top Abstract Introduction Patients and methods Results Discussion References

 

1. Lange H.W., Olsen J.D., Pedersen W.R., et al. Transesophageal color Doppler echocardiography of the normal St. Jude Medical mitral valve prosthesis. Am Heart J 1991;122:489-494.[Medline]
2. Skudicky D., Skoularigis J., Essop M.R., Rothlisberger C., Sareli P. Prevalence and clinical significance of mild paraprosthetic ring leaks and left atrial spontaneous echo contrast detected on transesophageal echocardiography three months after isolated mitral valve replacement with a mechanical prosthesis. Am J Cardio 1993;72:848-851.
3. Horstkotte D., Korfer R., Seipel L., Bircks W., Loogen F. Late complications in patients with Bjork-Shiley and St. Jude Medical heart valve replacement. Circulation 1983;68(Suppl II):175-184.
4. Movsowitz H., Shah S.I., Ioli A., Kotler M.N., Jacobs L.E. Long-term follow-up of mitral paraprosthetic regurgitation by transesophageal echocardiography. J Am Soc Echocardiogr 1994;7:488-492.[Medline]
5. Pu M., Vandervoort P.M., Griffin B.P., et al. Quantification of mitral regurgitation by the proximal convergence method using transesophageal echocardiography. Circulation 1995;92:2169-2177.[Abstract/Free Full Text]
6. Vandervoort P., Rivera J.M., Mele D., et al. Application of color Doppler flow mapping to calculate effective regurgitant orifice area. Circulation 1993;88:1150-1156.[Abstract/Free Full Text]
7. Bargiggia G.S., Tronconi L., Raisaro A., et al. Color Doppler diagnosis of mechanical prosthetic mitral regurgitation. Am Heart J 1990;120:1137-1142.[Medline]
8. Flachskampf F.A., O’Shea J.P., Griffin B.P., Guerrero L., Weyman A.E., Thomas J.D. Patterns of normal regurgitation in mechanical valve prostheses. J Am Coll Cardiol 1991;18:1493-1498.[Abstract]

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