Evaluating the etiology of mechanical valve obstruction: use of clinical parameters, fluoroscopy, and echocardiography

Evaluation and Management of Mechanical Heart Valve Dysfunction and Thrombosis

PURPOSE OF REVIEW

Dysfunction and thrombosis of mechanical heart valves, although uncommon, represents a challenge that requires multidisciplinary expertise for diagnosis and management. The aim of this review is to summarize strengths and weaknesses of diagnostic methods and therapeutic strategies for this uncommon but potentially life-threatening pathology.

RECENT FINDINGS

Expeditious diagnosis of mechanical valve thrombosis and exclusion of other diagnostic considerations, often with incorporation of multimodality imaging, can inform the best treatment strategy. Presentation of mechanical valve thrombosis can be asymptomatic or can include heart failure, life-threatening embolic events, or cardiogenic shock. Echocardiography, fluoroscopy and computed tomography are important in the evaluation of mechanical valve dysfunction. Therapeutic strategies for thrombosis include anticoagulation, systemic thrombolysis, and surgery. Choice of treatment depends on multiple factors including thrombus size, degree of valve dysfunction, clinical presentation, and available surgical expertise.

Artificial aortic valve dysfunction due to pannus and thrombus - different methods of cardiac surgical management

INTRODUCTION

Approximately 60 000 prosthetic valves are implanted annually in the USA. The risk of prosthesis dysfunction ranges from 0.1% to 4% per year. Prosthesis valve dysfunction is usually caused by a thrombus obstructing the prosthetic discs. However, 10% of prosthetic valves are dysfunctional due to pannus formation, and 12% of prostheses are damaged by both fibrinous and thrombotic components. The authors present two patients with dysfunctional aortic prostheses who were referred for cardiac surgery. Different surgical solutions were used in the treatment of each case.

CASE STUDY 1

The first patient was a 71-year-old woman whose medical history included arterial hypertension, stable coronary artery disease, diabetes mellitus, chronic obstructive pulmonary disease (COPD), and hypercholesterolemia; she had previously undergone left-sided mastectomy and radiotherapy. The patient was admitted to the Cardiac Surgery Department due to aortic prosthesis dysfunction. Transthoracic echocardiography revealed complete obstruction of one disc and a severe reduction in the mobility of the second. The mean transvalvular gradient was very high. During the operation, pannus covering the discs' surface was found. A biological aortic prosthesis was reimplanted without complications.

CASE STUDY 2

The second patient was an 87-year-old woman with arterial hypertension, persistent atrial fibrillation, and COPD, whose past medical history included gastric ulcer disease and ischemic stroke. As in the case of the first patient, she was admitted due to valvular prosthesis dysfunction. Preoperative transthoracic echocardiography revealed an obstruction of the posterior prosthetic disc and significant aortic regurgitation. Transesophageal echocardiography and fluoroscopy confirmed the prosthetic dysfunction. During the operation, a thrombus growing around a minor pannus was found. The thrombus and pannus were removed, and normal functionality of the prosthetic valve was restored.

CONCLUSIONS

Precise and modern diagnostic methods facilitated selection of the treatment method. However, the intraoperative view also seems to be crucial in individualizing the surgical approach.

ECG-gated MDCT after aortic and mitral valve surgery

OBJECTIVE

The purpose of this article is to review the utility of ECG-gated MDCT in evaluating postsurgical findings in aortic and mitral valves. Normal and pathologic findings after aortic and mitral valve corrective surgery are shown in correlation with the findings of the traditionally used imaging modalities echocardiography and fluoroscopy to assist in accurate noninvasive anatomic and dynamic evaluation of postsurgical valvular abnormalities.

CONCLUSION

Because of its superior spatial and adequate temporal resolution, ECG-gated MDCT has emerged as a robust diagnostic tool in the evaluation and treatment of patients with postsurgical valvular abnormalities.

Diagnostic evaluation of left-sided prosthetic heart valve dysfunction

Prosthetic heart valve (PHV) dysfunction is a rare, but potentially life-threatening, complication. In clinical practice, PHV dysfunction poses a diagnostic dilemma. Echocardiography and fluoroscopy are the imaging techniques of choice and are routinely used in daily practice. However, these techniques sometimes fail to determine the specific cause of PHV dysfunction, which is crucial to the selection of the appropriate treatment strategy. Multidetector-row CT (MDCT) can be of additional value in diagnosing the specific cause of PHV dysfunction and provides valuable complimentary information for surgical planning in case of reoperation. Cardiac magnetic resonance imaging (CMR) has limited value in the evaluation of biological PHV dysfunction. In this Review, we discuss the use of established imaging modalities for the detection of left-sided mechanical and biological PHV dysfunction and discuss the complementary role of MDCT in this context.

[Perioperative anticoagulation management for prosthetic heart valves]

OBJECTIVES

The practices and the guidelines over the perioperative management of the anticoagulation of patients with cardiac valves prothesis are the object of no consensual attitude. The thrombotic risk over the time is well known. It depends of the type or the location on the valve, of their associations and the age of the patient. In the perioperative period, the antithrombotic treatment must be interrupted according to the surgical haemorrhagic risk.

STUDY DESIGN

Short review.

RESULTS

Only patients, without associated risk factor, carriers of bioprosthesis from more than 3 months, can be maintained only under antiplatelets agents. In others situations, the caution imposes a bridge of anticoagulants from 48 to 72 hours with unfractionated heparin (subcutaneous at home, intravenous at the hospital). Low molecular weight heparin has no commercial authorization in this indication. The resumption of the anticoagulation by unfractionated heparin in postoperative period must be the most premature possible after the decrease of the surgical bleeding. The relay by vitamin K antagonists has to be made over 48 to 72 hours. Within the framework of the urgency, the surgical haemorrhagic risk is weak for an INR <1.5. According to the urgency of the surgery, a treatment by vitamin K (if the delay is over 12 hours) or by prothrombinic complex allows to correct this INR. The identification of thrombotic complications requires a particular attention. In the postoperative period, as soon as there is suspicion of thrombosis, clinical manifestations must be consolidated by the practice of a transoesophageal echography, which only confirm the diagnosis.