The facial-bone fractures among fatally injured car occupants in frontal collisions.

The retrospective study was performed of all deceased car-occupants in frontal car collisions in order to identify persons with facial-bone fractures. The sample consisted of 482 cases: 378 males and 104 females, average age of 39.59+/-16.01 years. There were 239 car-drivers, 194 front-seat passengers, and 49 rear-seat passengers. In 46 of 482 cases, single fracture of upper facial bones was established: nasal fractures were the most common, followed by zygomatic. In 118 of 482 cases, fracture of upper facial bones was established, as well as 70 cases of jawbone. The fractured facial bones either of the upper or lower face could not be a factor that predicts the position of the deceased in the motor vehicle at the moment of injury (lambda=0.989, p>0.05). The multi-fractured facial-bones were very often associated with the multi-fractured cranial bones - 85 cases (chi(2) =138.75, df=8, p<0.001), as well as jawbone fracture - 35 cases (chi(2) =20.52, df=4, p<0.001). Brain injuries were more present and more severe (coup and contrecoup-contusion and brain laceration) if more facial-bone fractures were involved (chi(2) =147.99, df=8, p<0.001). Cases with only contrecoup brain contusions, associated with multi-fractured facial-bones, were rare - 6 of 118. These fractures are very often associated with cranial fractures, as well as with brain injuries and were caused by intensive contact of the deceased's head with the car's pillar.

Concentration of carbon-monoxide in carbonized bodies--forensic aspects.

The aim of this paper is to determine the correlation between carbonized fire victims' carbon-monoxide (CO) blood concentration and the cause of death. We have reevaluated and analyzed the causes of death over a 10-year period regarding CO concentrations and atherosclerosis. We have considered the possible usefulness of low CO concentrations as a vital sign in smokers and non-smokers. The study included the retrospective analyzes of 73 autopsy reports of carbonized bodies. All the autopsies were carried out in the Institute of Forensic Medicine in Belgrade over a 10-year period (1990-1999). The investigation included 53 men and 20 women (chi(2)=19.83, p<0.001) with an average age of 41.40+/-21.35 years. We found 10 cases of deadly carbon-monoxide poisoning, but further analysis of CO concentrations revealed 6 more cases in which CO poisoning could be considered. We found a statistically significant relationship between carboxyhaemoglobin concentration above 10% and the aspiration of soot (chi(2)=6.41, p<0.01). In five cases with serious atherosclerosis, the concentration of carboxyhaemoglobin was above 20%, although these concentrations can be accepted as the cause of death. Half of the deceased, in the moment of death were under the influence of alcohol and 19 of them had a blood alcohol concentration above 1 pro mille.

Characteristics of chest injury in falls from heights.

This study included 660 victims injured due to high fall. All cases are with injuries caused by the free-fall model of high fall. The range of the heights was from 0 to 70 m. The sample was divided into three groups of growing height: low falls up to 7 m, high falls from 7 to 30 m, and very high falls above 30 m. Statistical analysis was performed using two way ANOVA according to Scheirer-Ray-Hare in complete uneven block. Males were 71% (469), females 29% (191). In the analyzed sample, apart from the height of fall, the number of accidents is about 44% (290 cases) and suicides about 56% (370 cases). Thirty six percent, i.e., 238 of 660 victims had consumed alcohol before death (alcoholemia >0.5 per thousand). The objective of our study was to analyze characteristics of chest injuries made by falling from a height. The frequency of thoracic injuries is statistically significantly related to the height of fall (p<0.05); it increases constantly in falls from heights beyond 3m, so that the rib fractures were present in all falls from heights beyond 40m. The aortic ruptures were found in 21%, and the heart injuries in 16% of all cases. The frequency of aortic and heart ruptures was not statistically significantly related to the height of fall (p>0.05). A rupture of the aorta was the most commonly located on its arch (82%). The heart ruptures were the most commonly located on the atrial posterior wall (70%).

Kinetic-photometric determination of iodide based on its inhibitory effect on the bromate oxidation of Victoria Blue 4-R.

A new sensitive kinetic method has been developed for the determination of trace amounts of I- over the range of 50-300 ng cm(-3). The method was based on the inhibitory effect of iodide on the oxidation of Victoria Blue 4-R by KBrO3. The reaction is monitored spectrophotometrically at 596.3 nm. Method development includes optimization of reagent concentration and temperature. The kinetic parameters of the reaction were reported and a rate equation was suggested. The effects of certain foreign ions upon the reaction rate were determined for the assessment of the selectivity of the method. The proposed method was successfully applied to the determination of iodide in real samples. The new developed method was found to have fairly good selectivity, sensitivity, simplicity and rapidity.

Contraction-relaxation coupling: determination of the onset of diastole.

Left ventricular relaxation is dependent on afterload conditions during systole. An abrupt increase in afterload while the ventricle is actively contracting prolongs the duration of systole. An increase in afterload during ventricular relaxation shortens the duration of systole. Therefore, we hypothesized that the point during systole when an abrupt increase in afterload had no effect on the duration of systole represented the onset of ventricular relaxation. To determine when this point occurs, we performed aortic occlusions progressively throughout the duration of systole in six dogs. We determined the change in systolic time (t(sys)) after an intervention normalized to t(sys) of a control beat (t(sys,i)/t(sys, c)) as a function of systolic occlusion time as a percentage of total systolic time (t(occ)/t(sys,c)), where t(sys) is the duration from time of left ventricular end-diastolic pressure to the time of minimum first derivative of left ventricular pressure. Our results show the onset of left ventricular relaxation during normal ejection occurs at 34 +/- 3% of systolic time and approximately 16% after the onset of ejection. Thus the beginning of relaxation occurs soon after the beginning of ejection, suggesting that relaxation is modulated by variable loading conditions during ejection, significantly before what has been conventionally been assumed to be the beginning of ventricular relaxation.

Estimation of regional left ventricular wall stresses in intact canine hearts.

Left ventricular (LV) wall stress is an important element in the assessment of LV systolic function; however, a reproducible technique to determine instantaneous local or regional wall stress has not been developed. Fourteen dogs underwent placement of twenty-six myocardial markers into the ventricle and septum. One week later, marker images were obtained using high-speed biplane videofluoroscopy under awake, sedated, atrially paced baseline conditions and after inotropic stimulation (calcium). With a model taking into account LV pressure, regional wall thickness, and meridional and circumferential regional radii of curvature, we computed average midwall stress for each of nine LV sites. Regional end-systolic and maximal LV wall stress were heterogeneous and dependent on latitude (increasing from apex to base, P < 0.001) and specific wall (anterior > lateral and posterior wall stresses; P = 0. 002). Multivariate ANOVA demonstrated only a trend (P = 0.056) toward increased LV stress after calcium infusion; subsequent univariate analysis isolated significant increases in end-systolic LV wall stress with increased inotropic state at all sites except the equatorial regions. The model used in this analysis incorporates local geometric factors and provides a reasonable estimate of regional LV wall stress compared with previous studies. LV wall stress is heterogeneous and dependent on the particular LV site of interest. Variation in wall stress may be caused by anatomic differences and/or extrinsic interactions between LV sites, i.e., influences of the papillary muscles and the interventricular septum.

Left ventricular diastolic function of remodeled myocardium in dogs with pacing-induced heart failure.

In patients with heart failure, decreased contractility resulting in high end-diastolic pressures and a restrictive pattern of left ventricular filling produces a decrease in early diastolic filling, suggesting a stiff ventricle. This study investigated the elastic properties of the myocardium and left ventricular chamber and the ability of the heart to utilize elastic recoil to facilitate filling during pacing-induced heart failure in the anesthetized dog. Elastic properties of the myocardium were determined by analyzing the myocardial stress-strain relation. Left ventricular chamber properties were determined by analyzing the pressure-volume relation using a logarithmic approach. Elastic recoil was characterized using a computer-controlled mitral valve occluder to prevent transmittral flow during diastole. We conclude that, during heart failure, the high end-diastolic pressures suggestive of a stiff ventricle are due not to stiffer myocardium but to a ventricle whose chamber compliance characteristics are changed due to geometric remodeling of the myocardium. The restrictive filling pattern is a result of the ventricle being forced to operate on the stiff portion of the diastolic pressure-volume relation to maintain cardiac output. Slowed relaxation and decreased contractility result in an inability of the heart to contract to an end-systolic volume below its diastolic equilibrium volume. Thus the left ventricle cannot utilize elastic recoil to facilitate filling during heart failure.

Septal function during left ventricular unloading.

BACKGROUND: Left ventricular (LV) unloading with mechanical support devices alters biventricular geometry and impairs right ventricular (RV) contractility, but its effect on septal systolic function remains unknown. METHODS AND RESULTS: To evaluate the effects of LV volume and pressure unloading on septal geometry and function, LV preload was abruptly reduced by clamping left atrial pressure between 0 and -2 mm Hg in seven open-chest, anesthetized dogs by use of a pressure-control servomechanism to withdraw blood from the left atrium. With left atrial pressure clamping, maximal LV pressure decreased 30 +/- 12% (mean +/- SD) (P < .0001) and LV end-diastolic cross-sectional area (determined by two-dimensional echocardiography) decreased by 53 +/- 16% (P < .0001). This caused the septum to shift toward the left (RV septal free-wall dimension increased; P < .004) and flatten (radius of curvature increased; P < .0002), while LV septal free-wall dimension fell (P < .0001). Septal end-diastolic thickness increased 23 +/- 15% (P < .0005), reflecting a decline in septal preload. Systolic septal thickening decreased (P < .002), while systolic septal output (Septal Output = Septal Thickening x Heart Rate) fell from 30 +/- 17 to 15 +/- 22 cm/min (P < .002). This was associated with movement along the septal Frank-Starling equivalent (septal output versus end-diastolic septal thickness [preload] relation) to a less productive portion of the curve. CONCLUSIONS: LV unloading not only altered interventricular septal geometry but also reduced septal systolic thickening and output, all of which may contribute to impaired RV contractility during mechanical LV support.

A computer-controlled aortic and mitral valve occluder.

To study cardiac mechanics, it is important to study the beat-to-beat changes in the heart. Left ventricular diastolic filling properties are determined by a passive component and an active component due to ventricular relaxation that occur simultaneously. To separate the active and passive components of ventricular filling, we designed a computer-controlled mitral valve occluder that prevents left ventricular filling. A computer-controlled aortic occluder was designed to change afterload conditions that could affect the components of ventricular filling. Experiments in six dogs demonstrated that these devices effectively control ventricular inflow and ejection on a beat-to-beat basis. The computer-controlled aortic and mitral occluders have a more accurate triggering and occlusion timing system than the previously reported techniques. This computer-controlled device enabled us to separate the passive component of filling from the active component, ventricular relaxation, and to alter afterload simultaneously, which will allow us to develop a better understanding of how ventricular filling and ejection is controlled on a beat-to-beat basis.

Redox potential measurements of plasma in patients undergoing coronary artery bypass graft and its clinical significance.

The apparent redox potentials (Em) of plasma as a marker of oxidant injury during coronary artery bypass graft (CABG) is determined, and their clinical significance is discussed. We measured plasma Em of normal volunteers (n = 20) and samples drawn at different time points from patients undergoing elective CABG (n = 60) directly and by adding 5 microl (20 mM) oxidants or reductants with known redox potential to plasma (95 microl), using a micro Pt/AgCl combination redox electrode. The Em value stays elevated up to 30 min during the surgery, after the administration of protamine it came down toward a more reduced state. Similar changes are seen with the lactate pyruvate ratio. Smaller changes of Em than normal are observed in plasma samples from patients treated with Aprotinin (antiprotease), Carmeda (heparin-coated) circuit and aspirin reflecting their protective effect. Redox potential (Em) measurements appear to be effective and useful in monitoring redox shifts wherever oxidative stress needs to be monitored.

Time to dP/dtmax reflects both inotropic and chronotropic properties of cardiac contraction: a conscious dog study.

This study supports a mathematical model and previous findings indicating that td, the time from onset of contraction to dP/dtmax, reflects the time-dependent aspects of contraction and hence decreases with increasing contractility. Combined data from 20 conscious instrumented dogs create a highly significant inverse and linear td-HR (heart rate) relation. Both norepinephrine and isoproterenol decreased td values, but norepinephrine, in contrast to isoproterenol, decreased the heart rate by a reflex response. Despite the remarkable decline in heart rate (25.8%) td was decreased (16.5%). During wide spontaneous R-R variations longer preceding intervals gave shorter td values. The latter two facts indicate the dependence of td on the contractile state rather than it being merely interval dependent.

Viscoelastic behavior of the isolated guinea pig left ventricle in diastole.

To determine left ventricular (LV) viscoelastic properties during acute volume changes, the relaxation of LV pressure (2-Fr, Millar) at steady LV volume after a known volume change was measured in 14 isolated guinea pig left ventricles arrested in diastole. The left ventricle was loaded and unloaded by manual injection and withdrawal of saline in 10 x 0.1-ml steps, controlling the steadiness of LV volume by measuring LV major and minor diameters (ultrasonic crystals). Cyclic stepwise volume loading and unloading resulted in a hysteresis loop, the complexity of which was caused by stress relaxation at each steady volume. With the use of linear regression analysis, the gross elastic effect of the pressure signal was separated from the viscoelastic part, decomposed into the fast and the slow component with time constants of relaxation equal to 1 and 20 s, respectively. The amplitudes of the fast and the slow component showed that 1) stress relaxation is more expressed at higher LV volume and 2) it is asymmetric, i.e., it is well expressed during volume loading and almost absent during volume unloading. Both suggest that viscoelasticity of passive myocardium is not quasilinear, when the left ventricle is subjected to aperiodic volume loading to a high LV volume. The asymmetric viscoelastic behavior is consistent with the hypothesis of extracellular fluid filtration.

Improving methods of chordal-sparing mitral valve replacement--Part II: Optimal tension for chordal resuspension.

BACKGROUND AND AIMS OF THE STUDY: Although chordal-sparing mitral valve replacement (MVR) is popular, the optimal tension for preserved or reattached chordae tendineae (CT) or for synthetic (ePTFE) CT is unknown. METHODS: Changes in left ventricular (LV) systolic and diastolic function in nine dogs with anterior CT preservation with different levels of end-diastolic chordal tension (0, 10, 20, 30, and 40 gm, measured by spring scale) were compared using an isovolumic double-balloon technique. RESULTS: LV function data at each level of tension were compared to control data using 0 gm of tension. Systolic function assessed as Emax (mmHg/ml) at 10, 20, 30, and 40 gm versus control was: 5.7 +/- 2.6/4.9 +/- 2.7, 4.7 +/- 2.2/4.7 +/- 2.7, 4.8 +/- 3.1/4.7 +/- 2.8, and 5.0 +/- 3.5/5.1 +/- 2.9; delta improvement from the control at 10 gm was larger than that at 20 gm (p < 0.05 by paired t-test). Diastolic function assessed as diastolic stiffness (Sd, mmHg/ml) at the same CT tensions versus control was: 0.56 +/- 0.23/0.56 +/- 0.34, 0.53 +/- 0.30/0.57 +/- 0.37, 0.56 +/- 0.39/0.52 +/- 0.38, and 0.60 +/- 0.36/0.58 +/- 0.39; delta Sd was smaller at 20 gm than at 30 gm (p = 0.05 by ANOVA). LV equilibrium volume (Veq, ml) was: 10.7 +/- 3.9/10.1 +/- 3.9, 9.6 +/- 3.4/9.9 +/- 3.8, 10.8 +/- 4.0/10.3 +/- 3.4, and 10.6 +/- 4.0/10.6 +/- 3.5; delta Veq was larger (i.e., more compliant chamber) at 10 gm than at 40 gm (p < 0.05 by rm-ANOVA). Arrhythmias precluding satisfactory measurements occurred in two dogs at 30 or 40 gm CT tension. CONCLUSIONS: With chordal tension exceeding 10 gm, which is barely palpable, there was no additional enhancement in LV systolic function compared to zero CT tension. Veq was largest at the lowest tension; LV diastolic function (assessed as Sd) deteriorated with tensions of 30 gm or higher. The optimal end-diastolic tension of preserved CT should enhance systolic LV performance without adversely affecting diastolic function; in this isovolumic model, minimal CT tension (10 gm) best met these goals. Excessive tension may negate the potential hemodynamic benefits of chordal preservation during mitral valve replacement.

Improving methods of chordal-sparing mitral valve replacement--Part III: Optimal direction for artificial chordae.

BACKGROUND AND AIMS OF THE STUDY: The optimal direction to preserve artificial chordae tendineae (CT) during mitral valve replacement (MVR) is not known, especially in regard to the response to inotropic stimulation which simulates exercise conditions. METHODS: Using a non-distorting isovolumic balloon technique, we compared left ventricular (LV) systolic and diastolic mechanics in 11 dogs in a control state (no chordal sparing) and with four different methods of chordal preservation: posterior, anterior, oblique (anterior papillary muscle chordae directed anteriorly and others posteriorly, the direction which theoretically augments LV systolic twist), and counter-oblique (counter, chordae preserved in directions opposite to oblique). RESULTS: Before dobutamine, delta Emax from the control was: 0.32 +/- 0.82, 0.10 +/- 0.43, 0.64 +/- 1.07, and 0.51 +/- 0.78 (anterior, posterior, oblique, and counter method, respectively). With dobutamine (3 mg/kg/min), delta Emax (mmHg/ml) was: 0.41 +/- 1.21, -0.13 +/- 0.75, 0.59 +/- 0.82*, and -0.34 +/- 0.71. Before dobutamine, delta LV stiffness (Sd, mmHg/ml) was -0.01 +/- 0.09, -0.02 +/- 0.12, 0.02 +/- 0.10, and 0.01 +/- 0.12; with dobutamine it was 0.01 +/- 0.09, 0.00 +/- 0.15, 0.03 +/- 0.15, and -0.06 +/- 0.11. Similarly, before dobutamine delta LV equilibrium volume (Veq) was -1.2 +/- 3.8, -0.3 +/- 3.0, -0.7 +/- 2.7, and -0.2 +/- 3.5, whereas with dobutamine zeta eq was -0.1 +/- 1.1, -0.4 +/- 0.8, 0.6 +/- 1.7, and -0.4 +/- 1.1. (Mean +/- S.D.; *p = 0.005 posterior and counter by ANOVA; p = NS (< 0.06) versus counter and posterior by ANOVA). CONCLUSIONS: The oblique method enhanced systolic LV function both with and without dobutamine, while a tendency towards better diastolic LV function (Veq) was observed with dobutamine. The anterior method was next best in preserving systolic function, both with and without dobutamine. LV diastolic function tended to deteriorate with dobutamine in the posterior group. Systolic function with the counter method deteriorated with dobutamine. These results warrant further study in an ejecting model to investigate LV systolic and diastolic mechanics with the oblique method of CT preservation, including interactions with LV systolic twist and diastolic recoil.

Left ventricular diastolic suction with zero left atrial pressure in open-chest dogs.

We investigated left ventricular (LV) diastolic volume changes (suction inflows) with left atrial pressure (LAP) clamped to ambient pressure in six open-chest, anesthetized dogs. The left atrium was cannulated and connected to a servo pump, and LAP was clamped to a set point near 0 mmHg for four beats by withdrawing blood. LAP averaged 5.88 +/- 1.44 mmHg before the clamp and fell to 0.74 +/- 0.61 mmHg (P < 0.0001) after the clamp. During the first clamped beat a transmitral pressure gradient of 1.0 +/- 0.6 mmHg was observed, resulting in LV filling of 2.6 +/- 1.8 ml. Subsequent beats developed suction-driven (mean negative LV pressure: -1.5 +/- 1.3 mmHg; P < 0.005 vs. zero) LV filling of 4.5 +/- 2.8 ml/beat with a peak transmitral pressure gradient of 1.7 +/- 0.6 mmHg. These data are consistent with the hypothesis that LV suction can be an important filling mechanism under condition in which LV end-systolic volume is reduced, e.g., reduced filling pressures, high heart rates, exercise, or increased inotropic drive.

Time to dP/dtmax, a preload-independent index of contractility: open-chest dog study.

A mathematical model of left ventricular pressure (LVP) during isovolumic contraction in the time domain shows the following predictions: 1) td, the time from onset of contraction to dP/dtmax and (dP/dt)/P, reflect only the time-dependent aspects of contraction, and are independent of preload; 2) dP/dtmax depends on both preload and the time-dependent aspects of contraction. To test preload independence we reduced filling volume (FV) by the method of ventricular volume clamps with a remote-controlled mitral valve in 7 anesthetized open-chest dogs. A decrease in FV of 80 +/- 15% produced a 29 +/- 12% (p < 0.001) decrease in LVP, 34 +/- 13% (p < 0.001) decrease in dP/dtmax, 13 +/- 4% (p < 0.001) decrease in t-dP/dtneg, and no change in td (-3 +/- 5%, NS). The heart rate (HR) dependence on td was assessed in other 5 anesthetized open-chest dogs. HR was changed with atrial pacing (50-240 bpm). td was linearly and inversely related to HR in each dog, and at each HR: dobutamine lowered and propranolol elevated this relation when compared to control (p < .001, both). Since dP/dtmax occurs usually before the opening of the aortic valve, td is, thus, also afterload-independent. Conclusion. This study supports the theoretical predictions that td is independent of preload and that it can serve, at any given HR, as a reliable index of contractility, provided that dP/dtmax occurs before the opening of the aortic valve.

Left ventricular function, twist, and recoil after mitral valve replacement.

BACKGROUND: Preservation of the mitral subvalvular apparatus during mitral valve replacement (MVR) has become more popular, in part because of the clinically and experimentally demonstrated more optimal left ventricular (LV) performance after surgery; the mechanisms responsible for this beneficial influence, however, have not been clearly elucidated. METHODS AND RESULTS: Fourteen dogs underwent placement of 26 myocardial markers into the LV and septum. One week later, the animals were studied while awake, sedated, and atrially paced (120 beats per minute) both under baseline conditions and after inotropic stimulation (calcium). The animals then underwent MVR and were randomized into either chord-sparing (MVR-Intact) or chord-severing (MVR-Cut) techniques. Two weeks later, the animals were studied under the same conditions. LV systolic function was assessed by the slope of the end-systolic pressure-volume relation (Ees); early LV diastolic filling was analyzed by the pressure-time constant of relaxation (tau). The instantaneous longitudinal gradient of torsional deformation for the LV (twist) was also calculated, as were the changes in twist with respect to time during systole and early diastole (LV recoil). Intergroup comparison showed a trend toward increased contractility (Ees, P = .061, before versus after MVR), as well as faster relaxation for the MVR-Intact group. Concurrent analysis of LV systolic function and the rate of systolic twist revealed a significant inverse relation, which disappeared after MVR when the chordae were severed. CONCLUSIONS: These observations suggest that the mitral subvalvular apparatus acts as a modulator of LV systolic torsional deformation into LV pump (or ejection) performance.