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Coagulation activity and emboli counts in patients with prosthetic cardiac valves
D Georgiadis1, A Mallinson, D G Grosset
1University Department of Medicine and Therapeutics, Western Infirmary, Glasgow, Scotland, UK.
Insights
Emboli detected in prosthetic heart valve patients are likely not from blood clots, as coagulation markers showed no correlation. Higher anticoagulation intensity above an international normalized ratio of 3.5 did not further reduce coagulation activity.
Area of Science:
- Cardiovascular Medicine
- Hematology
- Biomedical Engineering
Background:
- The source of embolic material detected via transcranial Doppler ultrasound in patients with prosthetic heart valves is not well understood.
- Investigating the relationship between Doppler emboli signals and coagulation system activity is crucial for understanding embolic sources.
Purpose of the Study:
- To evaluate the correlation between the number of transcranial Doppler emboli signals and markers of coagulation system activity.
- To determine if embolic material in prosthetic heart valve patients is thrombotic in origin.
Main Methods:
- Transcranial Doppler ultrasound monitoring for 30 minutes in 120 patients with prosthetic heart valves and 20 patients in atrial fibrillation.
- Measurement of plasma concentrations of D-dimer, antithrombin-III, and thrombin-antithrombin III complex.
Main Results:
- No significant correlation was found between coagulation parameters (D-dimer, antithrombin-III, thrombin-antithrombin III complex) and the number of Doppler emboli.
- D-dimer levels were higher in patients with mechanical prosthetic valves and lower international normalized ratio (INR) < 2.0 compared to higher INR.
- Specific mechanical valve types (Medtronic-Hall) showed higher D-dimer levels compared to others (Björk-Shiley, Carpentier-Edwards).
Conclusions:
- The absence of correlation suggests that the embolic material in prosthetic heart valve patients is unlikely to be thrombotic.
- Increased anticoagulation intensity to an INR > 3.5 does not appear to further suppress coagulation system activity in mechanical prosthetic valve patients.
Background And Purpose:
The underlying embolic material detected by transcranial Doppler ultrasound in patients with prosthetic heart valves remains unknown. We undertook this study to evaluate the relation between the number of Doppler emboli signals and the activity of the coagulation system.
Methods:
Patients with various types of prosthetic valves (n = 120) and patients in atrial fibrillation (n = 20) were monitored for 30 minutes using transcranial Doppler with a 2-MHz probe. The plasma concentrations of cross-linked D-dimer, antithrombin-III, and thrombin-antithrombin III complex were measured.
Results:
No correlation between the levels of any of the hematologic parameters and the number of emboli was demonstrated in the studied groups. The D-dimer levels were significantly higher in patients with mechanical prosthetic valves with an international normalized ratio under 2.0 compared with those with an international normalized ratio between 2 and 3.5 or above 3.5, and in patients with Medtronic-Hall versus Björk-Shiley or Carpentier-Edwards valve prostheses.
Conclusions:
The lack of correlation between the activity of the coagulation system and the number of Doppler emboli in patients with prosthetic valves suggests that the underlying embolic material in these patients is not thrombotic. Our results also suggest that an increase of the anticoagulation intensity to an international normalized ratio above 3.5 does not result in a further decrease of the activity of the unstimulated coagulation system in patients with mechanical prosthetic valves.