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European Journal of Echocardiography Advance Access published online on April 14, 2008
European Journal of Echocardiography, doi:10.1093/ejechocard/jen138
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Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2008. For permissions please email: journals.permissions@oxfordjournals.org

‘Obstruction alternans’ of a Sorin tilting disc prosthetic mitral valve: a case of emergency action

Loukianos S. Rallidis1,*, Costas Papadopoulos1, John Kanakakis2, Ioannis Paraskevaidis1 and Dimitrios T. Kremastinos1

1 Second Department of Cardiology, Attikon Hospital, School of Medicine, University of Athens, Athens, Greece
2 Department of Clinical Therapeutics, Alexandra Hospital, School of Medicine, University of Athens, Athens, Greece

Received 9 January 2008; .

* Corresponding author. Tel: +30 210 992 9106; fax: +30 210 5832351. E-mail address: rallidis{at}ath.forthnet.gr


   Abstract
Top
 Abstract
Introduction
 Discussion
 Supplementary material
 References
 
We present a patient with a history of a Sorin tilting disc prosthetic mitral valve implanted 20 years ago who developed acute dyspnoea. Echocardiogram revealed a unique pattern of ‘obstruction alternans’ of mitral valve prosthesis due to pannus formation. We emphasize the need for urgent surgical treatment of this potentially fatal complication.

Keywords: Mitral prosthesis; Tilting disc; Obstruction alternans


   Introduction
Top
 Abstract
 Introduction
Discussion
 Supplementary material
 References
 
Obstruction of mechanical prosthetic valves is an infrequent event nowadays due to the improved design and quality of the prosthetic material. Thrombosis or pannus formation is the most common causes of obstruction of mechanical valves.1,2 The distinction between thrombus and pannus formation is essential since thrombolysis can be applied in selected cases of thrombotic obstruction while reoperation is the only treatment in symptomatic obstruction caused by pannus formation.3 We describe a patient with acute dyspnoea whose Sorin tilting disc prosthetic mitral valve showed a pattern of ‘obstruction alternans’ due to pannus formation. The need for urgent surgical treatment is emphasized.

Case history
A 55-year-old woman was admitted to our cardiology clinic for evaluation of paroxysmal episodes of dyspnoea over the past 10 days. She had a history of mechanical mitral valve (25 mm Sorin tilting disc) replacement in 1986 and both tricuspid (33 mm Sorin Bicarbon bileaflet) and aortic valve (19 mm CarboMedics bileaflet) replacement in 2004 due to rheumatic valve disease. The patient was well until 2 months ago when she started complaining of dyspnoea on moderate effort. At that time, echocardiographic study revealed a mild stenosis of mitral valve prosthesis. Ten days ago, she started to experience acute episodes of dyspnoea lasting 10–20 minutes without obvious triggering factors.

Clinical examination on admission was unremarkable. Electrocardiogram showed atrial fibrillation (pre-existing) with good ventricular response and blood tests showed mild normochromic anaemia and INR of 2.8. Echocardiogram showed no abnormality except from a highly echogenic, dense, and thickened mitral valve disc suggestive of pannus formation and a mildly stenotic mitral valve prosthesis (mean gradient 7 mmHg). Her medical treatment consisted of acenocumarol, carvedilol 6.25 mg twice daily, spirinolactone 12.5 mg daily, digoxin 0.25 mg daily, and frusemide 40 mg daily.

Two days later, she developed acute dyspnoea and urgent echocardiogram revealed an ‘obstruction alternans’ pattern of the mitral prosthesis. Two-dimensional echocardiogram (see Supplementary material online, Video S1), colour flow Doppler (see Supplementary material online, Video S2), M-mode (Figure 1), and continuous-wave Doppler (Figure 2) revealed severe restriction of disc opening every second cycle. There was no any mass in proximity to mitral prosthesis.


Figure 1
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  		Figure 1 (A) M-mode of mitral valve prosthesis showing the alternating opening of the disc. Notice that there are two consecutive cycles [fourth (white arrow) and fifth (black arrow)] with very restricted disc opening due to the short RR interval of fourth cardiac cycle with inadequate increase in left atrial pressure of this cycle and failure of the following beat to raise left atrial pressure above the required level to open the disc (B) M-mode of aortic bileaflet valve prosthesis with normal opening. Notice that the duration of valve opening is shorter every second beat, and (C) M-mode of tricuspid bileaflet valve prosthesis with normal opening.

 


Figure 2
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  		Figure 2 Continuous-wave Doppler of mitral valve tilting disc prosthesis. White arrows show the transmitral continuous-wave pattern of a mildly stenotic valve (mean gradient 7 mmHg) and black arrows (faint Doppler signal) the pattern of a severely stenotic valve (mean gradient 17 mmHg).

 
The demonstration of intermittent mitral valve obstruction in association with patient’s clinical condition was considered as a case of urgent surgery. The patient was referred for surgery but she died 30 minutes later while waiting transportation to another hospital with cardiothoracic department.


   Discussion
Top
 Abstract
 Introduction
 Discussion
Supplementary material
 References
 
Nowadays, the frequency of prosthetic mitral valve obstruction has been markedly decreased due to the improvement in the design and material of mechanical prostheses. However, a variety of factors, such as thrombosis, pannus formation, bacterial endocarditis, chordal debris, papillary muscle entrapment, etc. can cause mechanical malfunctions of prosthetic heart valves either perioperatively or long after the surgical replacement.1,4–6 Thrombosis or pannus formation is considered as the most common causes of prosthetic mitral valve obstruction. The differentiation between these two entities by clinical parameters and echocardiographic findings is not always easy. Short duration from time of valve insertion to malfunction, inadequate anticoagulation, shorter duration of symptoms, and the presence of relatively large soft masses on the valve favours the diagnosis of thrombus.2

We report a patient with intermittent obstruction of a Sorin tilting disc mitral valve prosthesis implanted 20 years ago. This condition is associated with clinical symptoms ranging from dyspnoea and presyncope to pulmonary oedema and sudden cardiac death.7 Our patient presented with episodes of acute dyspnoea and echocardiography revealed a unique pattern of ‘obstruction alternans’ only when performed during acute dyspnoea. Echocardiogram on admission did not reveal such abnormality. Therefore, this pattern of dysfunction was intermittent and the most likely cause of the acute episodes of dyspnoea over the past 10 days. Transoesophageal echocardiography in our patient failed to demonstrate the presence of a thrombus attached to the valve but showed a heavily thickened disc of mitral valve prosthesis suggestive of pannus formation.

To our knowledge, there are only few cases in the literature with intermittent obstruction of a tilting disc mechanical mitral prosthesis due to pannus tissue growing over the valve.8,9 However, the pattern of ‘obstruction alternans’ is extremely rare and has been previously reported in a bileaflet prosthetic mitral valve.10 An explanation for this pattern in our patient is as follows: the heavily thickened disc requires more force to open. When the disc remains in an almost closed position, blood accumulates in left atrium increasing left atrial pressure. During the next cardiac cycle, the high transmitral gradient is sufficient to open the disc resulting in a mildly obstructed pattern. The identical repeat of this phenomenon generated the ‘obstruction alternans’ pattern.

Intermittent obstruction of a prosthetic mechanical valve caused by pannus formation favours acute valve thrombosis with subsequent fixed valve obstruction and cardiogenic shock. Therefore, this potentially catastrophic complication requires urgent valve replacement. Unfortunately, our patient died of cardiogenic shock while waiting for transportation to another hospital with cardiothoracic centre.

In conclusion, episodes of acute dyspnoea in the setting of mechanical valves should always raise the suspicion of intermittent valve obstruction when other causes of dyspnoea are absent. Urgent transthoracic and transoesophageal study is essential to confirm the diagnosis. When pannus formation is identified as the cause of obstruction, urgent surgical treatment is the only treatment.


   Supplementary material
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 Abstract
 Introduction
 Discussion
 Supplementary material
References
 
Supplementary material is available in the online version.


   References
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 Abstract
 Introduction
 Discussion
 Supplementary material
 References
 

  1. Vitale N, Renzulli A, Agozzino L, Pollice A, Tedesco N, de Luca Tupputi Schinosa L, et al. Obstruction of mechanical mitral prostheses: analysis of pathologic findings. Ann Thor Surg (1997) 63:1101–6.[Abstract/Free Full Text]
  2. Barbetseas J, Nagueh SF, Pitsavos C, Toutouzas PK, Quiñones MA, Zoghbi WA. Differentiating thrombus from pannus formation in obstructed mechanical prosthetic valves: an evaluation of clinical, transthoracic and transesophageal echocardiographic parameters. J Am Coll Cardiol (1998) 32:1410–7.[Abstract/Free Full Text]
  3. Alpert JS. The thrombosed prosthetic valve. Current recommendations based on evidence based medicine. J Am Coll Cardiol (2003) 41:659–60.[Free Full Text]
  4. Keeble W, Cobbe S. Pressure damping, a ‘billowing’ septum, and aneerie silence: perioperative, intermittent obstruction of a mitral valve prosthesis. Heart (2000) 84:e6.[CrossRef][Medline]
  5. Borowski A, Reiss N, Klaer R. Intermittent obstruction of the Omnicarbon-valve prosthesis in the mitral position due to interference by papillary muscle. Diagnostic and surgical considerations. J Cardiovasc Surg (Torino) (1992) 33:305–7.[Medline]
  6. Pai GP, Ellison RG, Rubin JW, Moore HV, Kamath MV. Disc immobilization of Björk-Shiley and Medtronic Hall valves during and immediately after valve replacement. Ann Thorac Surg (1987) 44:73–6.[Abstract]
  7. Arana Rueda E, Florián Sanz F, Gómez Navarro C, Nevado Portero J, Aguilera Saborido A, López Pardo F. Mitral prosthetic valve and presyncope. An Med Intern (2005) 22:241–3.
  8. Hornung RS, Dunn FG, Simpson I. Intermittent obstruction of a Bjork-Shiley mitral valve prosthesis—an unusual diagnosis aided by Doppler ultrasound. Scott Med J (1987) 32:136–7.[Web of Science][Medline]
  9. Shahid M, Sutherland G, Hatle L. Diagnosis of intermittent obstruction of mechanical mitral valve prostheses by Doppler echocardiography. Am J Cardiol (1995) 76:1305–9.[CrossRef][Web of Science][Medline]
  10. Varadarajan P, Jutzy KR, Pai RG. Unique Doppler pattern of ‘obstruction alternans’ of a St Jude prosthetic mitral valve. J Am Soc Echocardiogr (2003) 16:890–3.[CrossRef][Web of Science][Medline]

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This Article
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