Prosthetic Valve Obstruction Research Articles

EVALUATION OF PROSTHETIC VALVE FUNCTION AND ASSOCIATED COMPLICATIONS

Significant advances in imaging modalities have occurred to evaluate prosthetic valve function and associated complications. These developments involve predominantly the introduction of Doppler technology for the non-invasive determination of gradients and valve areas and TEE for an improved assessment of valve structure, function, and associated complications. The current role of cinefluoroscopy is mostly to complement TEE in the evaluation of motion of mechanical prosthetic valves in the aortic position. Cardiac catheterization is now rarely needed to assess valve function. Diagnosis of prosthetic valve obstruction can be performed in the majority of cases with transthoracic Doppler echocardiography. Differentiation of valve obstruction from normal valve function in small valves with high flow conditions, however, may be difficult. Because of this and the variability in normal valves among different prostheses, knowledge of the type and size of the implanted valve is essential. Patients and ultrasound laboratories are encouraged to seek and provide this information on a routine basis. Although transthoracic echocardiography is the main diagnostic modality for the serial evaluation of prosthetic valve function, it is important to recognize its limitations in assessing prosthetic mitral regurgitation and evaluating structural abnormalities of prosthetic valves. These are the situations in which TEE has the most impact. A summary of general indications of TEE in prosthetic valves is provided in Table 6. Finally, a baseline transthoracic Doppler study is essential in the overall follow-up and serial evaluation of valve function. For future comparisons, the best indices of valve functions are those obtained for patients as their own control, from a baseline Doppler echocardiographic study performed early after the operation.

Evaluation of a Bileaflet Aortic Valve Prosthesis Before and After Thrombolytic Tissue Plasminogen Activator Therapy by Continuous Wave Doppler Ultrasound

Thrombotic obstruction of mechanical prosthetic valves is a frequently encountered cause of prosthetic valve dysfunction, which can result in stenosis and regurgitation. 1 We present a case of thrombotic obstruction of a bileaflet mechanical aortic valve prosthesis that resulted in severe stenosis and regurgitation. Considering the known risk factors associated with both surgical and thrombolytic treatments, a decision was made to use tissue plasminogen activator therapy to relieve the burden of the thrombotic valvular obstruction. In this case review, we use continuous wave Doppler to demonstrate recovery of normal valve function despite suboptimal two-dimensional imaging. (J Am Soc Echocardiogr 1998;11:478-9.)

Role of transesophageal echocardiography in differentiating pannus from thrombus in obstructed prosthetic valves

Role of transesophageal echocardiography in differentiating pannus from thrombus in obstructed prosthetic valves

Clinical Course and Hemodynamic Observations After Supraannular Mitral Valve Replacement in Infants and Children

Objectives. We report the clinical course and unique hemodynamic findings after placement of a supraannular mitral valve prosthesis.Background. Children with symptomatic mitral valve disease whose annulus is too small for the smallest prosthesis are difficult to manage. One option is valve replacement with a prosthesis positioned entirely within the left atrium (LA).Methods. We reviewed 17 patients (median age 10 months) with symptomatic mitral valve disease who underwent placement of a supraannular valve prosthesis between 1980 and 1994.Results. The actuarial survival rates were 88% at 1 month and 71%, 62% and 53% at 1, 2 and 10 years, respectively. Preoperative hemodynamic data (mean ± SD) compared with those after placement of the supraannular mitral prosthesis were as follows: “a” wave to left ventricular end-diastolic pressure gradient 17 ± 5 versus 4 ± 4 mm Hg (p = 0.003), mean LA pressure 25 ± 6 versus 20 ± 6 mm Hg (p = 0.07), “a” wave 30 ± 6 versus 19 ± 5 mm Hg (p = 0.006), “v” wave 28 ± 5 versus 30 ± 9 mm Hg (p = 0.31), mean pulmonary artery pressure 54 ± 19 versus 42 ± 15 mm Hg (p = 0.07) and left ventricular end-diastolic pressure 14 ± 5 versus 16 ± 4 mm Hg (p = 0.12).Conclusions. Supraannular mitral valve replacement provides relief of mitral stenosis or mitral regurgitation. However, LA to left ventricular early diastolic gradients with large atrial “v” waves contribute to elevated mean LA pressures in the absence of prosthetic valve obstruction or regurgitation. As a result of this unexpected finding, associated left heart obstructive lesions and pulmonary and left ventricular end-diastolic hypertension, the outlook remains poor.(J Am Coll Cardiol 1997;29:1089–94)© 1997 by the American College of Cardiology

Obstruction of mechanical valve prostheses: clinical diagnosis and surgical or nonsurgical treatment.

Twenty patients underwent nonsurgical and/or surgical treatment for obstruction of mechanical prosthetic valves. The obstructed prosthetic valve was in the aortic position in 11 patients, in the mitral position in 5, and in the tricuspid position in 4. Twelve patients had a bileaflet valve (3 aortic, 5 mitral, 4 tricuspid), and 8 had a tilting disk valve (all aortic). The diagnosis of prosthetic valve obstruction was made by cineradiography and echocardiography. Thrombolytic therapy was instituted in a series of our 10 most recent patients (11 cases), except for one patient with acute renal failure, regardless of the position of the obstructed prosthetic valve. Successful thrombolysis was achieved in 6 cases (54.5%). Six patients required surgical treatment subsequent to either failed or incomplete thrombolysis, and one patient died of congestive heart failure 1 month after surgery. Nonfatal neurologic events occurred in 2 cases (18.2%). A total of 16 patients underwent surgical treatment. Two (12.6%) of the 16 patients died of causes unrelated to the operative procedures before discharge from the hospital. These results suggest that thrombolytic therapy appears to be an attractive nonsurgical alternative for valve thrombosis when the patient's clinical condition is not critical, and thus surgical treatment should only be performed in an emergency on seriously ill patients.

Hypereosinophilic syndrome: Cause of prosthetic valve obstruction

Hypereosinophilic syndrome: Cause of prosthetic valve obstruction

Transesophageal echocardiography in critically ill patients: Feasibility, safety, and impact on management

Transesophageal echocardiography (TEE) is being used with increasing frequency in critically ill patients in whom transthoracic echocardiography (TTE) is often unsatisfactory in providing much needed information. We reviewed the indications, feasibility, and clinical impact of TEE in the intensive care setting at our institution. TTE was performed in 77 critically ill patients (age range 19 to 83 years) in whom TTE was inadequate or inconclusive. The general indications for performing a TEE were as follows: Hemodynamic instability (41%), possible endocarditis (34%), possible embolic source (21%), and possible aortic dissection (4%). In the subset of patients with hemodynamic instability, severe native mitral regurgitation was the most common underlying cause (25%), followed by hypovolemia after cardiac surgery (22%). TEE was feasible in all patients, 47% of whom were on mechanical ventilation. Two patients required stabilization before TEE, including a femoral artery-to-vein bypass in a patient with shock from a prosthetic valve obstruction. Complications, none of which proved to be fatal, occurred in two. Echocardiography led to a significant change in patient management in 46 of the 77 patients (60%), of which 48% was due solely to TEE. In these patients ( n = 37), the TEE findings led to a change in medical management in 19% and to surgical intervention in 29%. While TTE remains the first line of diagnostic ultrasound and Doppler in critically ill patients, it can be technically difficult or inconclusive. In this setting, TEE provides a safe and powerful diagnostic tool that can help guide patient management.

Prosthetic valve obstruction: Thrombolysis versus operation

An acute obstruction is a life-threatening complication of mechanical valve prosthcses, and is caused by the formation of fresh clot or fibrous tissue overgrowth/ or both. Accurate selection of the most appropriate treatment for a particular patient is mandatory. From January 1991 to July 1992, 28 cases of prosthetic thrombosis were nunaged. Twenty patients underwent surgical treatment, with one operative death, and 8 patients were treated with thrombolysis using recombirtanl tissue-type plasminogen activator (rt-PA). The criteria for using thrombolysis were (1) the recent onset of symptoms, (2) transesophageal echocardiographic evidence of clots on the valve or cardiac chambers, and (3) preserved disc excursions. All patients who underwent thrombolysis had mechanical valves (two bileaflets, four tilting discs, and two ball valves); seven valves were in the mitral position and one was in the aortic. Symptoms of obstruction consisted of cardiac failure in 6 cases or thromboembolism in 5, or both. The mean interval between the onset of symptoms and the initiation of thrombolysis was 81 ± 65 hours. After infusion of the rt-PA, normal valve function was restored in all patients, as documented by transesophageal echocardiography. No deaths or neurologic complications occurred; there was one episode of minor peripheral embolism. Thrombolysis using rt-PA may be the appropriate treatment in patients with primary thrombosis of mechanical valves, thereby avoiding the operation-related risks.

Massive Pulmonary Hemorrhage Complicating Mitral Prosthetic Valve Obstruction

A case is reported of prosthetic mitral valve obstruction in a patient who had had three hospital admissions with massive hemoptysis. A diagnosis was finally made after two-dimensional echocardiography with Doppler and cardiac catheterization were performed. The patient was successfully treated with re-replacement of the valve. Any new pulmonary or cardiac symptom in a patient with a prosthetic valve requires prompt evaluation and treatment.

Thrombolytic therapy for prosthetic valve thrombosis: A study based on serial Doppler echocardiographic evaluation

Sixteen patients with echocardiographic and cinefluoroscopic evidence of Björk-Shiley prosthetic valve obstruction (13 mitral valves and 3 aortic valves) were treated with intravenous streptokinase. Streptokinase was administered as an initial bolus of 250,000 units for 30 minutes, followed by an infusion of 100,000 units/hr. Serial cinefluoroscopy and echocardiography (M-mode, two-dimensional, and Doppler) were performed at 0, 24, 48, and 72 hours of treatment. The end point of treatment was defined as near normalization of clinical, echocardiographic, and fluoroscopic parameters. Successful thrombolysis was achieved in all patients. The average duration of streptokinase therapy was 43 hours (range 2 to 72 hours). Two of 16 patients had minor systemic embolism during therapy. Short-term follow-up has shown sustained benefit in 14 of 16 patients. Two patients have had rethrombosis of the mitral prosthetic valves and have undergone thrombectomy. Our study demonstrates the feasibility, safety, and efficacy of thrombolytic therapy in the treatment of prosthetic valve thrombosis. It also emphasizes the role of serial Doppler echocardiography in guiding the duration of therapy and assessing its efficacy.

Obstruction of mechanical heart valve prostheses: Clinical aspects and surgical management

One hundred patients (32 male) aged 5 months to 82 years (median 32 years) underwent 106 surgical procedures for 112 mechanical prosthetic valves obstructed by a thrombus (n = 61) or pannus (n = 7), or both (n = 44), between January 1, 1980 and December 31, 1989. The position of the obstructed prosthesis was aortic in 51 patients (48%), mitral in 49 (46%) and both aortic and mitral in 6 (6%). The types of obstructed prosthetic valves were Björk-Shiley (n = 51), St. Jude (n = 41) and Medtronic-Hall (n = 20). The time interval between valve replacement and obstruction ranged from 6 weeks to 13 years (median 4 years). Of 63% of patients in whom coagulation variables were available at the time of obstruction, 70% were receiving inadequate anticoagulant therapy. In 63% of the procedures the patient was in New York Heart Association functional class IV. Two patients underwent preoperative thrombolysis with incomplete results. Operative procedures included valve replacement (n = 81), valve declotting and excision of pannus (n = 23) and aortic valve replacement and mitral valve declotting (n = 2). The early mortality rate was 12.3% (13 patients), and there was no difference between surgery for mitral prostheses (12.2%) versus aortic prostheses (13.7%). The perioperative mortality rate was 17.5% (11 of 63 patients) in patients in functional class IV and 4.7% (2 of 43 patients) in those in functional classes I to III (p less than 0.05). For valve replacement, the mortality rate was 12% (10 of 81 patients) and for declotting of the prosthesis 13% (3 of 23 patients).(ABSTRACT TRUNCATED AT 250 WORDS)

Doppler echocardiographic characteristics of normal and dysfunctioning prosthetic valves in the tricuspid and mitral position.

The Doppler echocardiographic characteristics of 70 prosthetic valves in 35 patients are reported. Twenty nine patients had a Björk-Shiley prosthesis in both mitral and tricuspid positions and six had Carpentier-Edwards valves in both sites. Five of the patients had abnormal tricuspid prostheses on the basis of clinical and echocardiographic criteria. Pulsed wave Doppler echocardiography was used in all examinations. The pressure half times for the normal tricuspid prosthetic valves, 105 (40) ms (Björk-Shiley) and 97 (53) ms (Carpentier-Edwards), were significantly longer than those of normal mitral prosthetic valves, 75 (18) ms (Björk-Shiley) and 83 (15) ms (Carpentier-Edwards). The range of pressure half times for the abnormal tricuspid valves (237-530 ms) was distinct from that of the apparently normal tricuspid prosthetic valves (38-197 ms). There was an increase in the peak velocity of the obstructed tricuspid prosthetic valves (1.69 (0.12) m/s) in comparison with normal prostheses (1.06 (0.26) m/s). The normal range of pressure half times for the Björk-Shiley and Carpentier-Edwards valves in the mitral position is not applicable to the same valves in the tricuspid position. The valve appears to function well with very long pressure half times but a pressure half time of greater than 200 ms coupled with a peak velocity of greater than 1.60 ms without significant valve regurgitation indicates tricuspid obstruction of the tricuspid prosthetic valve.

Doppler Echocardiography: Application to the Assessment of Successful Thrombolysis of Prosthetic Valve Thrombosis

Prosthetic valve thrombosis remains a significant problem despite anticoagulation therapy and advances in valve design. Thrombolytic therapy offers an alternative approach to valve replacement in patients with high surgical risk. In this article we discuss three cases in which Doppler echocardiography was used to confirm the diagnosis of prosthetic mitral valve obstruction and serially monitor the response of valvular hemodynamic measurements to thrombolysis with intravenous streptokinase. These cases illustrate how the Doppler technique, in addition to allowing the noninvasive diagnosis of prosthetic valve obstruction, is presently the ideal tool to follow serially the effect of thrombolytic therapy on prosthetic valve function.

Doppler echocardiography in prosthetic valve dysfunction. Diagnostic value in twenty cases.

We performed a retrospective study of 20 cases of prosthetic valve dysfunction which required reoperation and in which preoperative Doppler studies were performed. There were 13 mitral (3 mechanical, 10 bioprostheses) 5 aortic (1 mechanical and 4 bioprostheses), 1 pulmonary bioprosthesis and 1 mechanical tricuspid valve dysfunction. The aim of the study was to establish the diagnostic value of the Doppler examination by comparing the results with the operative findings. The parameters measured were: peak pressure gradient and mean pressure gradients in all prostheses, together with pressure half times and functional surface area in mitral and tricuspid valve prostheses. Cardiac catheterisation was performed in 6 cases before surgery. The diagnosis of prosthetic valve obstruction was correctly made, even in the 1 case with moderate stenosis. All cases of regurgitation were diagnosed and the topographical location of the leak was identified, except in 1 mechanical mitral valve prosthesis in which the regurgitant jet was detected only by continuous wave Doppler. Fourteen of the 20 cases were reoperated upon without catheterisation. These results suggest that Doppler echocardiography is a sensitive and specific diagnostic method of assessing prosthetic valve dysfunction. However, as the Doppler parameters are variable from one prosthesis to another, it is important to perform pulsed and continuous wave Doppler baseline studies in the immediate postoperative period as a reference in case of suspected valve dysfunction at a later stage.

Paradoxical embolism secondary to tricuspid valve endocarditis

closure and was more likely to result in changes in heart rate and pressures. We now only attempt to cross through the major orifice. In patient 3, ascending aortic angiography was performed to quantitate AR before (1+) and after (3+) insertion of the probing catheter. We were surprised that this increased magnitude of AR was not associated with important changes in aortic and PCW pressures. In all 4 patients the procedure was tolerated without complication. No symptoms or hemodynamic deterioration occurred despite the probing catheter remaining in the left ventricle for up to 10 minutes. Fluoroscopic time to cross the prosthesis varied between 1 and 5 minutes. Hemodynamic changes noted with the probing catheter across the aortic prosthesis included consistent mild elevation of PCW pressure. Aortic pressure and heart rate did not consistently change. These alterations did not appear to be of sufficient magnitude to interfere with evaluation of aortic valve systolic and mitral valve diastolic function. This technique is easily performed without apparent risk. It allows measurement of LV pressure and permits evaluation of the aortic valve prosthesis and mitral valve. Although AR is created by the probing catheter across the valve, it appears to be less severe than that created with larger left heart catheters. We believe that we were able to accurately assess aortic valve systolic gradients and prosthetic valve obstruction. Unfortunately, the 4Fr catheter is too small to allow sufficient contrast injection for LV angiography. An aortic root injection with a separate catheter can opacify the left ventricle adequately for evaluation of contractile function and mitral valve competence. Although our experience is limited to a few cases, it demonstrates a useful alternative to other techniques for invasive ass e s s m e n t of aortic tilting disc prosthetic valve function. This system may also be applicable to evaluation of certain other mechanical valves in the aortic position and we have used it successfully in some cases of severe native valve aortic stenosis.

Calcification of Glutaraldehyde-Preserved Porcine and Bovine Xenograft Valves in Young Children

Eight children (mean age, 7.6 years) had xenograft prosthetic valves inserted. All developed evidence of prosthetic valve obstruction requiring reoperation 18 to 55 months after insertion (mean, 32 months). At operation, all the valves were found to be heavily calcified. There were two perioperative deaths. Of two patients who had a second xenograft valve inserted, one died suddenly 12 months later. Gross calcification of the xenograft was found at postmortem examination. The other patient had evidence of mild xenograft calcification at follow-up 19 months postoperatively. Four of the ten calcified xenograft valves were of bovine origin (Ionescu-Shiley type); in these the calcific obstruction occurred significantly earlier than in the six porcine (Hancock) valves.

Echo-Phonocardiographic Evaluation of Obstruction of Prosthetic Mitral Valve

Echo-phonocardiograms of 64 patients with multiple types of prosthetic mitral valves (PMV) were evaluated. Six patients demonstrated findings suggesting valve obstruction: four had surgical confirmation of prosthetic obstruction, one reduced cardiac output and pulmonary hypertension but no prosthetic dysfunction at surgery, and one is asymptomatic. Three of four patients with confirmed obstruction had variable second sound to opening click intervals (A2-MO) with interrupted disc opening; two had interrupted disc closure with split closing clicks and three of four had reduced diastolic closure rate. In 58 clinically well patients with PMV, cycle-to-cycle A2-MO varied little: 0-10 msec in sinus rhythm and 10-25 msec in atrial fibrillation. Diastolic closure rates of five different types of PMV were similar: 21.6 mm/sec, (range 14-49). No patient had interrupted opening, closing or multiple closing clicks. Thus, delayed PMV opening or closure, altered A2-MO interval and double closing clicks are highly useful in detecting patients with obstruction of a variety of mitral prostheses.

A hitherto undescribed cause of prosthetic mitral valve obstruction

A case is described in which severe prosthetic mitral valve obstruction was produced by entanglement of sutures across the central axis of the prosthesis on its ventricular side. The entangled sutures prevented the tilting disc occluder from falling into the left ventricular cavity during ventricular diastole.

The assessment of mitral stenosis and prosthetic mitral valve obstruction, using the posterior aortic wall echocardiogram.

The echocardiographic motion of the aortic root reflects, in part, left atrial filling and emptying. Patients with mitral valve obstruction were studied to determine whether clinically important alterations in patterns of left atrial emptying would alter motion of the posterior aortic wall. Patients with mitral stenosis had a characteristic pattern of slowing of left atrial emptying in early diastole, with loss of the conduit phase in mid-diastole. The atrial emptying index, defined as the fraction of passive posterior aortic wall motion occurring in the first third of diastole, was significantly related to the mitral valve area index (r = 0.86), and thus provides a noninvasive quantitation of the degree of mitral stenosis. Determination of the atrial emptying index also proved useful in the evaluation of patients with prosthetic mitral valve obstruction and in documenting improvement in left atrial emptying after mitral valve surgery.

Malfunction of tricuspid valve prosthesis shown by isotope angiocardiography

Isotope angiocardiography established prosthetic tricuspid valve obstruction in a patient 6 years after triple valve replacement. Thrombus formation is a common complication of prosthetic cardiac valves, particularly in the tricuspid position where engagement of cage with myocardium is an additional potentially obstructive hazard. Comparison is made between the information yield of the isotope investigation and cardiac catheterization with contrast cineangiography. It is suggested that the isotope technique can noninvasively provide valuable anatomic and functional data, particularly where the right side of the heart is to be examined.