From Hartert's Thrombelastograph to Pathway-Specific Viscoelastic Testing: A Historical Sketch

Viscoelastic haemostatic testing is now widely used in clinical practice, but its adoption unfolded slowly. Introduced by Hellmut Hartert in 1948 as thrombelastography, it offered a dynamic whole-blood recording of clot initiation, propagation, strength, and lysis at a time when most coagulation testing relied on endpoint clotting times in plasma. Hartert and others applied the method clinically from the 1950s, and it reached the first human liver transplant programmes in the 1960s, yet for almost four decades it did not spread beyond individual centres. Its expansion required not only technical modernisation but also a conceptual change. The original thrombelastographic tracing represented coagulation as a broad, monolithic process. Successive generations of instruments and reagents progressively decomposed this single signal into interpretable functional modules through defined activators, platelet inhibitors, fibrinolytic challenge and drug-specific triggers. Mechanical cup-and-pin and probe systems (e.g., Hartert, ROTEM, ClotPro, Sonoclot), resonance with optical detection (e.g., TEG 6s), and ultrasound-based sonorheometry (e.g., Quantra) all follow a broader historical movement from global observation toward pathway-directed analysis of haemostasis. This historical sketch traces that trajectory from Hartert's mechanical instrument to today's viscoelastic assay panels, illustrating the long latency before clinical adoption, the methodological revival through standardised activators and perioperative algorithms, and the more recent development of assays directed at fibrinolysis and direct oral anticoagulants.