Marcus Carlsson
= Marcus Carlsson
{c}
\b[<Marcus Carlsson>] investigates cardiac pumping using <magnetic resonance imaging>. His 2007 primary study measured longitudinal atrioventricular-plane displacement and related it to <stroke volume> in twelve controls, twelve elite triathletes and twelve patients with <dilated cardiomyopathy>.<Atrioventricular plane displacement is the major contributor to left ventricular pumping in healthy adults, athletes, and patients with dilated cardiomyopathy by Marcus Carlsson and others>[Byline; Abstract, study groups and cine magnetic resonance imaging]{ref}
The study combined a longitudinal displacement with a short-axis area to estimate the longitudinal contribution to ejected volume.<Atrioventricular plane displacement is the major contributor to left ventricular pumping in healthy adults, athletes, and patients with dilated cardiomyopathy by Marcus Carlsson and others>[Abstract, calculation from mean epicardial area and displacement]{ref} A shorter displacement need not imply a proportionally smaller contribution when the chamber's transverse dimensions differ.
An original constant-area illustration gives
$$
V_{\rm long}=A\,s,\qquad q_{\rm long}=\frac{As}{V_{\rm stroke}}.
$$
With stipulated $A=40\,\mathrm{cm^2}$ and $s=1.0$ cm, the modeled contribution is 40 mL. Doubling area to $80\,\mathrm{cm^2}$ while halving displacement to 0.5 cm gives the same 40 mL. If total <stroke volume> is 80 mL in both examples, both longitudinal fractions are one half. These are geometric examples, not group values from the study.
This explains why comparing displacement alone and comparing its contribution to <stroke volume> are different questions. The experimental paper supplies actual images and a specified geometric estimator, while the toy model isolates the multiplication responsible for that distinction. Neither a displacement nor its volume fraction alone determines every aspect of ventricular function; <ejection fraction> also requires the corresponding chamber volume.
\Image[https://ki.se/profile-image/marcus-carlsson]
{title=Marcus Carlsson, named portrait linked from his Karolinska Institutet profile}
{height=300}