Helen Cheung

Frequency of myocardial injury after blunt chest trauma as evaluated by radionuclide angiography

Seventy-seven patients who had sustained multisystem trauma, including severe blunt chest injury, were prospectively evaluated to assess the frequency of associated traumatic myocardial injury. Traumatic injury to either the right or left ventricle was defined by the presence of discrete abnormalities of wall motion on electrocardiographically gated cardiac scintigraphy in patients without a clinical history of heart disease. Forty-two patients (55%) (Group 1) had focal abnormalities of wall motion; 27 involved the right ventricle, 7 the left ventricle, 7 were biventricular, and 1 involved only the septum. Both the right and left ventricular ejection fractions were significantly (p less than 0.01) lower (31 +/- 11% and 47 +/- 14%, respectively) than those in the 35 traumatized patients without wall motion abnormalities on scintigraphy (Group 2) (49 +/- 8% and 58 +/- 11%, respectively). Repeat scintigraphic examination in 32 Group 1 patients at a time remote from initial injury showed improvement or resolution of previously defined focal wall motion abnormalities in 27 of 32 patients (84%). The electrocardiogram and serum enzyme tests were insensitive indexes of traumatic myocardial injury when defined by the scintigraphic abnormalities. Thus, severe blunt chest trauma results in a higher frequency of traumatic myocardial injury than heretofore recognized, and frequently involves the anteriorly situated right ventricle.

Right and left ventricular performance in acute hypoxemic respiratory failure.

We examined biventricular performance on two occasions in 28 patients with acute hypoxemic respiratory failure (ARF), using a combination of invasively determined pressures and flows as well as radionuclide scin-tigraphy to measure the right and left ventricular ejection fractions (RVEF and LVEF, respectively). From the FF and concurrently measured thermodilution stroke volumes, we calculated right and left ventricular end-diastolic and end-systolic volume indices (FDVI and ESVI, respectively). Regression analysis demonstrated that changes (Δ) in global right ventricular function (RVEF) were inversely correlated with concurrent changes in the mean pulmonary arterial pressure (MPAP): Δ RVEF = 0.015 – 0.015 Δ MPAP (r2 = 0.60; p <.005), while an increase in right ventricular preload (RVEDVI) was positively correlated with changes in MPAP: Δ RVEDVI = 2.68 ± 6.27 Δ MPAP (r2 = 0.46; p <.005). Global left ventricular function (LVEF) was related to changes in systemic pressures as well as to right-sided events: Δ LVEF = −0.01 −0.0015(Δ RVESVI) + 0.001(Δ BP systolic) −0.42(CVP/RVEDVI) (r2 = 0.35; p <.01). These data confirm the significant influence of right ventricular afterload on RVEF in ARF patients and an apparent interrelationship between altered right ventricular systolic function and global left ventricular performance.

Nitroprusside infusion does not improve biventricular performance in patients with acute hypoxemic respiratory failure

We administered sodium nitroprusside (SNP) to ten patients with acute hypoxemic respiratory failure and associated pulmonary hypertension to examine the hypothesis that a reduction in the outflow pressure faced by the left (LV) and/or the right (RV) ventricle during ejection might be associated with an increase in cardiac index (Cl), hence an increase in systemic O 2 transport (O 2 t). We measured pressures and flows invasively and the right and left ventricular ejection fractions by gated scintigraphy before and during an infusion of SNP titrated to a reduction of the mean blood pressure (BP) and/or the mean pulmonary artery pressure (PAP) of 10% to 15%. SNP infusion (mean dose, 1.02 ± 0.62 μg/kg/min) (mean ± SD) resulted in a decrease in all of the mean BP (Δ −18 ± 22 mm/Hg; P P −5 /M 2 ; P −5 /M 2 ; P 2 t. At a dose resulting in a significant reduction in the mean outflow pressure faced by both the LV and the RV, an infusion of SNP was not associated with any substantial change of forward flow in patients with acute PAH complicating ARF.

Hemodynamic adaptation to acute myocardial contusion complicating blunt chest injury

Abstract The immediate hemodynamic sequelae of blunt chest injury complicated by acute myocardial contusion were examined in multiply traumatized patients. Focal defects of ventricular wall motion defined by gated cardiac scintigraphy identified acute myocardial contusion In 28 of 43 patients, involving the right ventricle alone in 18 (group 1A), the left ventricle In 4 (group 1B) and both ventricles in 6 (group IC). Qualitatively normal ventricular wall motion was found in the 15 patients (group 2). Although there was no difference between groups 1A and 2 in mean systemic oxygen transport (620 ± 189 vs 627 ± 105 ml/min/m2), left ventricular ejection fraction (52 ± 14% vs 60 ± 9%) or calculated left ventricular end-diastolic and end-systolic volumes, mean right ventricular (RV) ejection fraction was significantly lower in group 1A (29 ± 9%) than In group 2 (47 ± 7%, p 2 ) but not in group 2 (RV end-systolic volume, 50 ± 21 ml/m 2 , p 2 ) than in group 2 (RV end-diastolic volume 93 ± 26 ml/m 2 , p

Changes in myocardial blood flow rates during hyperdynamic sepsis with induced changes in arterial perfusing pressures and metabolic need

ObjectiveTo determine whether hyperdynamic sepsis is associated with dysregulation in the control of myocardial blood flow rates unrelated to hypotension or the use of anesthetic agents. DesignProspective, nonrandomized, controlled trial. SettingExperimental laboratory. SubjectsFifteen mature male sheep (34 to 61 kg). InterventionsData were recorded in study subjects before and after the induction of sepsis following cecal ligation and perforation. Data were then recorded during: a) an infusion of prostaglandin E1 (PGE1), which decreased mean arterial perfusing pressure; and b) an infusion of zymosan-activated plasma, which increased mean pulmonary arterial pressures. Measurements and Main ResultsMyocardial blood flow rates were measured by the radiolabeled microsphere technique and cardiac index was measured by the thermodilution technique. Cardiac index (change Δ) postcecal ligation and perforation minus baseline (+2.3 ± 1.0 L/min/m2; p <.01) was increased in the septic study. Blood flow rate to the left ventricle was simultaneously increased, and was not further affected when the PGE1 infusion decreased the mean arterial perfusing pressures (-19 ± 4%). During the infusion of zymosan-activated plasma, mean pulmonary arterial pressures increased (50 ± 30%) and right ventricular blood flow was increased (zymosan minus postcecal ligation and perforation study: Δ17.8 ± 50 mL/100 g/min; p <.01). ConclusionsIn this model of hyperdynamic sepsis, increases in blood flow to both the left and right ventricles were positively coupled to changes in respective ventricular work. From the interventional PGE1 and zymosan-activated plasma infusion studies, we found no evidence to support previous suggestions that the regulation of myocardial blood flow rates according to changes in perfusing pressure and/or metabolic oxygen need is significantly altered during hyperdynamic sepsis. (Crit Care Med 1993;21:1192–1199)