Microsoft word - thrombocheck final by sagie.doc
Initial clinical experience with hand – held device (Thrombocheck) for the detection of
bileaflet prosthetic valve malfunction
Ben Zekry S, Sagie A, MD, Ben-Dor I, MD, Nukrian H, ARDS, Battler A, MD, Shapira Y, MD.
Echocardiography unit, Department of Cardiology, Rabin Medical Center, Beilinson Campus,
Petah Tiqva, affiliated with Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel.
Early recognition of subclinical prosthetic valve (PV) malfunction may allow for early
treatment and avoidance of serious complications. Echocardiography cannot be applied on a
daily basis. Therefore a hand – held device (Thrombocheck) capable of detecting subtle
changes in the acoustic sounds of prosthetic valve has been developed for routine home
monitoring of heart valve function. We report our initial clinical experience with this device.
Seventy one consecutive patients with one or more bileaflet prosthetic mechanical valves at
any position were assessed both by transthoracic echocardiography (TTE), fluoroscopy and by
Thrombocheck. These patients attended our clinic for either routine echocardiography (62
patients) and for detection of prosthetic valve malfunction (9 patients).
The Thrombocheck was held for one minute in subxhiphoid position perpendicular to the
patient, and provided any of the 3 indications: OK – normal function of the PV; Warning – after
3 repeat measurements (1 min each) - abnormal function of the PV; No signal – the not identified
The study group had in total 82 bileaflet valves: 47 mitral, 31 aortic and 4 tricuspid.
There were 8 (10%) patients with "no signal" indication. Of the remaining 63 patients, there were
10 patients (18.9%) with WARNING alarm in whom 8 had echocardiographic and fluoroscopic
evidence of current abnormal leaflet motion, one patient has a recent history of abnormal leaflet
motion, and one patient had no evidence of prosthetic valve malfunction. The sensitivity and
specificity for detecting abnormal PV malfunction were 90% and 98%, respectively.
Thrombocheck had an excellent sensitivity and specificity for the detection of prosthetic
valve malfunction in a cohort of patients with bileaflet mechanical prosthetic heart valves.
Mechanical prosthetic heart valves carry a yearly complication rate of 2-3%, including
malfunction due to thrombosis and tissue ingrowth (1). These complications are associated with
high morbidity and mortality rate. Early recognition of subclinical prosthetic valve malfunction
may allow early treatment and avoidance of serious complications (hemodynamic instability or
thromboembolism). Echocardiography, which is used for routine follow up of patients with
prosthetic valves, cannot be applied on a daily basis and requires skilled echocardiographers.
Several reports showed typical pattern of closing of the prosthetic valves on real-time sound
spectroanalysis at normal condition and with dysfunction of the prosthetic valves (2-5).
Fritzsche et al showed that the acoustic sounds of the prosthetic valve remain constant under
similar conditions and that patients’ valve signals didn’t change significantly over 6 month
period (6). Animal studies showed that frequent control of the heart valve sounds can detect very
subtle changes in the integrity of the heart valve sounds before they lead to hemodynamic or
thromboembolic consequences, readily detectable by echocardiography (7).
Therefore a hand – held device (Thrombocheck) has been developed for routine home
monitoring of heart valve function. The individual signature of the heart valve sound is
computed from its acoustic information. It detects valve acoustic sounds in the region of 11 kHZ,
and is able to detect subtle changes in the acoustic sounds.
We report the results of routine use of this new hand – held device in clinical practice.
Seventy one consecutive patients with at least one bileaflet prosthetic mechanical valve at any
position who attended our clinic for either routine echocardiography or for detection of valve
malfunction, were assessed both by echocardiography and by hand–held device
(Thrombocheck). Transthoracic echocardiography was done with Sonos 5500 equipment
(Philips, Andover, MA, USA) with second harmonic capabilities. All the prosthetic valves were
carefully assessed both for hemodynamics and for leaflet motion in multiple views, as previously
reported (8). Transesophageal echocardiography (TEE) was done as needed with the same
echocardiographic machine and a multiplane 3.7/5 MHz probe.
Prosthetic valve malfunction was suspected when echocardiography showed high gradients
across the prosthetic valve or increased (>25%) gradient across the prosthetic valve comparing
the past examination, or inability to demonstrate full range motion of the two discs. In any case
of suspicion of valve dysfunction the patient was referred for fluoroscopy and/or TEE.
There were no exclusion criteria for testing the Thrombocheck. In patients with 2 prosthetic
valves with an immobilized leaflet in one of them, the analysis of diagnostic accuracy of the
device was applied to this very valve only. In the analysis of patients after mitral valve
replacement we included only the double disc mitral valve.
The Thrombocheck was set for double disc sounds. We used the same Thrombocheck
The Thrombocheck was held for one minute in subxhiphoid position perpendicular to the
patient, which was lying in a recumbent position. There were 3 optional textual results on the
OK – indicated normal function of the prosthetic valve.
Warning – after 3 repeat measurements (1 min each) indicated abnormal function of the
No signal – the Thrombocheck did not identify valve sounds.
Seventy one patients were enrolled (25 male, 46 female), aged 58.5 ± 13.3 years old (range 25
years – 82 years). These patients had in total 82 bileaflet valves: 47 mitral, 31 aortic and 4
The annular diameters of the mitral, aortic and tricuspid valves ranged from 25-31 mm (median
27 mm), 19-25 mm (median 21 mm), and 27-33 mm, respectively. The valve models included
were St Jude Medical (St. Paul, Minnesota, USA), CarboMedics (Sulzer Carbomedics, Austin,
Tx) and Sorin Bicarbon (Sorin Biomedica, Saluggia, Italy). There were 8 patients with "No
signal" indication (one of them was after isolated TVR). Out of the remaining 63 patients, there
was a WARNING alarm in 10 (18.9%) with the following clinical and echocardiographic
findings: 8 patients had evidence of current abnormal leaflet motion (Table 2); one patient had
no evidence of prosthetic valve malfunction, and one patient was two months after thrombolysis
therapy due to valve dysfunction and high gradient across the prosthetic valve. This patient was
readmitted several months later with obstructive valve thrombosis, and was reoperated. The
operative specimen showed combined thrombus and pannus formation. Six patients with
abnormal leaflet motion were tested with the device following anti-thrombotic or thrombolytic
treatment (Table 2). In 4 patients with successful thrombolysis, the Thrombocheck showed
normal PV function ("OK"). In one patient with anti-thrombotic treatment and chronic abnormal
leaflet motions there was a “No signal” indication. In one patient with recurrent hospital
admissions because of abnormal leaflet motions and known high pressure gradient on the mitral
valve due to prosthesis-patient mismatch, the Thrombocheck showed WARNING after
treatment, whereas the fluoroscopy showed normal discs movement, and the pressure gradient
across the mitral valve returned to baseline.
There was one patient after tricuspid valve replacement with chronic abnormal leaflet motion
in whom the Thrombocheck indicated OK.
Table 3 summarizes the testing results of the Thrombocheck and the impact of valve position
on its diagnostic accuracy. There were only one false positive test and one false negative test.
After exclusion patients with ”No signal” indication, the Thrombocheck had a sensitivity and
specificity of 90% and 98%, respectively, for the detection of prosthetic valve malfunction. The
subgroup analysis according to valve position indicates sensitivity of 100% and specificity of
97% for patients with MVR and 100% specificity and 95% sensitivity for patients with AVR.
In the current study the hand – held - Thrombocheck had an excellent sensitivity and
specificity (90% and 98%) for the detection of prosthetic valve malfunction in a cohort of
patients with bileaflets prosthetic heart valves, both for the mitral and the aortic position. A high
diagnostic accuracy is an invaluable prerequisite for the daily implementation of the
thrombocheck. We should not miss valve malfunction at one hand, and false alarm indications
are undesirable as well. The high sensitivity of the thrombocheck provides assurance for both
Two of our patients demonstrate the usefulness of the Thrombocheck. In one patient (number
8 in Table 2) the Thrombocheck provided various indications which paralleled with the leaflet
motion: it showed WARNING early after thrombolysis, and then OK after 7 months. A few
months later it could not be calibrated for this very patient for bileaflet valve, and a repeated
obstructive valve thrombosis was diagnosed. The other patient (number 9 in Table 2) with
moderately elevated aortic valve gradients (peak 50 mmHg, mean 30 mmHg) in a 19 mm
CarboMedics prosthesis, the Thrombocheck indicated WARNING. Fluoroscopy showed only
30 degree limitation of the combined travel angle of the valve. These examples represent the
high sensitivity of the Thrombocheck for the detection valve malfunction, even in
asymptomatic patients. This early recognition of subclinical prosthetic valve malfunction may
allow early treatment before development of serious complications which may lead to
hemodynamic instability, thromboembolism and death. It may also detect valve thrombosis at a
stage where the thrombus burden will not be associated with high complication rate when
Follow up of patients with valve malfunction who were treated (by either antithrombotic
therapy or intensified anticoagulation) showed resolution of the WARNING indication in four
patients. These resolutions of the WARNING indication further strengthens the reliability of the
Thrombocheck. The device may be especially suitable for patients with a prior history of
prosthetic valve malfunction. These patients have a higher likelihood of additional episodes,
Thrombocheck is planned for individual use and a previous study reported the use of
individual devices for patients without reporting any difficulty in detecting valve signal (7). In
10% of our patients the Thrombocheck indicated “No signal”. We do not know if this
indication reflects the limitation of the Thrombocheck, valve dysfunction, or (probably) the use
of the same hand–held device (same acoustic fingerprint) for all patients.
The number of patients in the current study is limited. In addition, we used the same hand –
held device for all patients. It is expected that if patients receive a personal device, and this
device will initially be checked for appropriate valve function, the accuracy of the device will
further improve. Moreover, those patients who will initially show "no signal" will not be offered
We report, for the first time, initial experience with the hand – held device - Thrombocheck
in the clinical practice. It is a simple and comfortable device for home monitoring with an
excellent sensitivity and specificity for the detection of prosthetic valve malfunction.
Nevertheless, we believe that it should serve as a screening tool, for assurance at one hand and
alert at the other hand, but it cannot replace echocardiography or fluoroscopy in the thorough
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Thrombolytic therapy for prosthetic valve thrombosis: short- and long-term results. Am Heart J.
AVR – aortic valve replacement, MVR – mitral valve replacement, TVR – tricuspid
*Two patients with single disc mitral valves.
** Two patients with biological tricuspid valves.
Table 2: Characteristic, therapy and outcome of patient’s with abnormal leaflet motions.
CM – CarboMedics. NA – Not available. SB – Sorin Bicarbon; SJM - St. Jude
This patient had recurrent abnormal leaflet motions
** OK after 7 months, device could not be calibrated for double disc at later follow-
up – with repeated valve obstruction.
Table 3: Effect of valve position on diagnostic accuracy of the Thrombocheck*
Number of patients
No signal indication (%)
Patients excluded from analysis due to
abnormality in an additional valve
Patients analyzed for diagnostic accuracy
AVR – mitral valve replacement; MVR – mitral valve replacement; TVR
– tricuspid valve replacement.
*The statistical analysis was done after exclusion patients with “No signal” indication.
** The associated abnormal valve was aortic in 2 patients and tricuspid in 1 patient.
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