Changes in Left Ventricular Torsion Early Postoperatively After Aortic Valve Replacement and at Long-Term Follow-up.

OBJECTIVE: In patients with aortic stenosis, left ventricular systolic torsion (pT) is increased to overcome excessive afterload. This study assessed left ventricular torsion before and immediately after surgical valve replacement and tested the instant effect of fluid loading. DESIGN: Prospective, clinical single-center study. SETTING: Intensive care unit of a university hospital. PARTICIPANTS: 12 patients undergoing elective aortic valve replacement for aortic stenosis. INTERVENTIONS: Echocardiography was performed on the day before surgery, within 18 hours after surgery including a fluid challenge, and after 2.5 years. MEASUREMENTS AND MAIN RESULTS: pT decreased early postoperatively by 21.2% (23.4° ± 5.6° to 18.4° ± 6.9°; p = 0.012) and reached preoperative values at 2.5 years follow-up (24 ± 7). Peak diastolic untwisting velocity occurred later early postoperatively (13% ± 8% to 21% ± 9.4%; p = 0.019) and returned toward preoperative values at follow-up (10.2 ± 4.7°). The fluid challenge increased central venous pressure (8 ± 4 mmHg to 11 ± 4 mmHg; p = 0.003) and reduced peak systolic torsion velocity (138.7 ± 37.6/s to 121.3 ± 32/s; p = 0.032). pT decreased in 3 and increased in 8 patients after fluid loading. Patients whose pT increased had higher early mitral inflow velocity postoperatively (p = 0.04) than those with decreasing pT. Patients with reduced pT after fluid loading received more fluids (p = 0.04) and had a higher positive fluid balance during the intensive care unit stay (p = 0.03). Torsion after fluid loading correlated with total fluid input (p = 0.001) and cumulative fluid balance (p = 0.002). CONCLUSIONS: pT decreased early after aortic valve replacement but remained elevated despite elimination of aortic stenosis. After 2.5 years, torsion had returned to preoperative levels.

Left ventricular torsion abnormalities in septic shock and corrective effect of volume loading: a pilot study.

BACKGROUND: Ventricular torsion is an important component of cardiac function. The effect of septic shock on left ventricular torsion is not known. Because torsion is influenced by changes in preload, we compared the effect of fluid loading on left ventricular torsion in septic shock with the response in matched healthy control subjects. METHODS: We assessed left ventricular torsion parameters using transthoracic echocardiography in 11 patients during early septic shock and in 11 age- and sex-matched healthy volunteers before and after rapid volume loading with 250 mL of a Ringer's lactate solution. RESULTS: Peak torsion and peak apical rotation were reduced in septic shock (10.2 ± 5.2° and 5.6 ± 5.4°) compared with healthy volunteers (16.3 ± 4.5° and 9.6 ± 1.5°; P = 0.009 and P = 0.006 respectively). Basal rotation was delayed and diastolic untwisting velocity reached its maximum later during diastole in septic shock patients than in healthy volunteers (104 ± 16% vs 111 ± 14% and 13 ± 5% vs 21 ± 10%; P = 0.03 and P = 0.034, respectively). Fluid challenge increased peak torsion in both groups (septic shock, 10.2 ± 5.3° vs 12.6 ± 3.9°; healthy volunteers, 16.3 ± 4.5° vs 18.1 ± 6°; P = 0.01). Fluid challenge increased left ventricular stroke volume in septic shock patients (P = 0.003). CONCLUSIONS: Compared with healthy volunteers, left ventricular torsion is impaired in septic shock patients. Fluid loading attenuates torsion abnormalities in parallel with increasing stroke volume. Reduced torsional motion might constitute a relevant component of septic cardiomyopathy, a notion that merits further testing in larger populations.

Elastodynamic wave propagation in graded materials: simulations, experiments, phenomena, and applications.

A two-dimensional numerical simulation model for the elastodynamic wave propagation in two linear elastic, isotropic, joint half-spaces is presented. The border between the two half-spaced is graded in a way, that the values of the elastic properties and the densities vary smoothly (sinusoidally) from the values of one continuum to the values of the other continuum within a transition zone of a defined thickness. It is demonstrated, that a graded layer leads to a frequency and wavelength dependent refraction and reflection behavior of elastodynamic waves. Numerical results show that wavelengths which are long compared with the transition layer thickness are dominantly reflected whereas short waves are dominantly transmitted, a phenomena which does not occur in the case of an infinitely thin transition layer. Furthermore the frequency dependent reflection and transmission behavior of elastodynamic waves is verified experimentally. There the interface between two vapor deposited films is graded due to intermetallic diffusion effects. These graded microstructures are analyzed with a short-pulse-laser-acoustic set-up. The corresponding frequencies of the elastodynamic waves which are filtered with these functionally graded microstructures are in the range of 0.5 THz.