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Biomedical subjects

J Gorcsan

Publications and source records attributed to J Gorcsan.

At least 37 records · Page 2Linked to original sources
PubMed1996

Improvement in pulmonary function and elastic recoil after lung-reduction surgery for diffuse emphysema.

BACKGROUND: Pulmonary function may improve after surgical resection of the most severely affected lung tissue (lung-reduction surgery) in patients with diffuse emphysema. The basic mechanisms responsible for the improvement, however, are not known. METHODS: We studied 20 patients with diffuse emphysema before and at least three months after either a unilateral or a bilateral lung-reduction procedure. Clinical benefit was assessed by measurement of the six-minute walking distance and the transitional-dyspnea index, which is a subjective rating of the change from base line in functional impairment and the threshold for effort- and task- dependent dyspnea. Pressure-volume relations in the lungs were measured with static expiratory esophageal-balloon techniques, and right ventricular systolic function was assessed by echocardiography. RESULTS: The patients had significant improvement in the transitional-dyspnea index after surgery (P<0.001). The mean (+/-SD) coefficient of retraction, an indicator of elastic recoil of the lung, improved (from 1.3+/-0.6 cm of water per liter before surgery to 1.8+/-0.8 after, P<0.001). Sixteen patients with increased elastic recoil had a greater increase in the distance walked in six minutes than the other four patients, in whom recoil did not increase (P=0.02). The improved lung recoil led to disproportionate decreases in residual volume as compared with total lung capacity (16 percent vs. 6 percent), but the decreases in both values were significant (P<0.001). Forced expiratory volume in one second increased (from 0.87+/-0.36 to 1.11+/-0.45 liters, P<0.001). End-expiratory esophageal pressure also decreased (P=0.002). These improvements in lung mechanics led to a decrease in arterial partial pressure of carbon dioxide form 42+/-6 to 38+/-5 mm Hg (P=0.006). Furthermore, the fractional change in right ventricular area, an indicator of systolic function, increased from 0.33+/-0.11 to 0.38+/-0.010 (P=0.02). CONCLUSIONS: Lung-reduction surgery can produce increases in the elastic recoil of the lung in patients with diffuse emphysema, leading to short-term improvement in dyspnea and exercise tolerance.

Adult↗
PubMed1996

Immediate effects of lung transplantation on right ventricular morphology and function in patients with variable degrees of pulmonary hypertension.

OBJECTIVES: This study sought to determine the immediate effects of lung transplantation on right ventricular morphology and function in patients with variable degrees of pulmonary hypertension and to evaluate these features as potential markers of immediate outcome. BACKGROUND: Selected lung transplant recipients with severe preoperative pulmonary hypertension have previously been shown to have a reduction in right ventricular size and improved function at follow-up evaluation. METHODS: Thirty-two consecutive patients (mean [+/- SD] age 44 +/- 11 years) were prospectively classified into three groups according to their pretransplantation pulmonary artery systolic pressure: severe pulmonary hypertensive group > or = 75 mm Hg, intermediate pulmonary hypertensive group 40 to 74 mm Hg and non-pulmonary hypertensive group < 40 mm Hg. Hemodynamic and transesophageal echocardiographic variables were measured immediately before and after lung transplantation. RESULTS: Pulmonary artery systolic and mean pressures markedly decreased after transplantation in the severe pulmonary hypertensive group (from 115 +/- 26 to 45 +/- 19 mm Hg and from 76 +/- 14 to 31 +/- 11 mm Hg, respectively, both p < 0.05). Mean pulmonary artery pressure decreased in the intermediate group (from 34 +/- 7 to 26 +/- 7 mm Hg, p < 0.05). Right ventricular end-diastolic area, end-systolic area and eccentricity index decreased in the severe pulmonary hypertensive group after transplantation. End-diastolic area also decreased in the intermediate pulmonary hypertensive group. Right ventricular fractional area change was not significantly different between groups and did not change consistently after transplantation. Three patients with severe pulmonary hypertension who had continued depression of right ventricular function after transplantation died in the immediate postoperative period. CONCLUSIONS: Lung transplantation is associated with an immediate decrease in pulmonary artery pressures and right ventricular size and normalization of septal geometry but variable changes in right ventricular function. Continued depression of right ventricular fractional area change may be a potential marker of poor outcome.

Adult↗
PubMed1996

Color-coded measures of myocardial velocity throughout the cardiac cycle by tissue Doppler imaging to quantify regional left ventricular function.

TDI is a new echocardiographic technique that calculates and displays color-coded myocardial velocity on-line. To determine the feasibility of endocardial velocity throughout the cardiac cycle as a means to quantify regional function, 20 normal subjects aged 30 +/- 5 years and 12 patients with heart disease aged 62 +/- 17 years were studied with a prototype TDI system. TDI M-mode images were acquired by using a multicolored velocity map (display range, -30 to 30 mm/sec; temporal resolution, 90 Hz). Color-coded velocity data were then converted to numeric values off-line at 50 msec intervals. Posterior wall velocities throughout the cardiac cycle by TDI were closely correlated with velocity calculations from the first derivative of routine digitized M-mode tracings (group mean r = 0.88 +/- 0.03, SEE = 7.0 +/- 1.1 mm/sec). Anteroseptal TDI color-coded systolic velocity occurred 164 +/- 84 msec from the onset of the electrocardiographic QRS compared with 203 +/- 33 msec in the posterior wall (P < 0.05) in normal subjects, consistent with normal electrical activation. Significant differences in systolic and diastolic posterior wall TDI velocity data were observed in patients with hypokinetic or akinetic segments assessed by independent routine study when compared with normal controls. Calculated systolic and early diastolic posterior wall TDI indexes correlated significantly with percentage of wall thickening. Of abnormal anteroseptal segments, TDI systolic time velocity integrals were significantly different than normal and correlated with percentage of wall thickening. TDI has potential to quantitatively assess regional left ventricular function.

Adult↗
PubMed1996

Left ventricular pressure-volume relations with transesophageal echocardiographic automated border detection: comparison with conductance-catheter technique.

Pressure-volume relations are important means used to assess left ventricular (LV) contractility; however, on-line volume acquisition has been limited to the invasive conductance catheter. The objective was to compare simultaneous measures of LV volume by transesophageal echocardiographic automated border detection (ABD) and conductance catheter and their respective pressure-volume relations during steady state and alterations in preload and contractility. Seven dogs had placement of high-fidelity pressure and conductance catheters, a vena caval balloon occluder, and a transesophageal probe. An automated Simpson's rule volume algorithm was used from the transverse four-chamber view. Inotropic modulation was induced with dobutamine in four dogs and propranolol in three. Relative changes in ABD volume were linearly related to conductance volume at steady state with group mean r = 0.93 +/- 0.03, standard error of estimate (SEE) = 10 +/- 2%. Changes in end-diastolic volume, end-systolic volume, and stroke work with caval occlusion were also significantly correlated:r = 0.93 =/- 0.04, SEE = 3.6 ml; r = 0.89 +/- 0.04, SEE = 3.8 +/- 1.9 ml; and r = 0.86 +/- 0.05, SEE = 40 +/- 21 mJ, respectively. The overall bias was for absolute ABD volume to be less. End-systolic and maximal elastance values by ABD were significantly higher than by the conductance method; baseline group average 4.97 +/- 0.92 mm Hg/ml versus 2.70 +/- 1.15 mm Hg/ml and 6.63 +/- 1.66 mm Hg/ml versus 3.20 +/- 1.37 mm Hg/ml (p<0.05), respectively. However, the direction and relative magnitude of changes in elastance with inotropic modulation were similar.

Analysis of Variance↗
PubMed1996

Potential influence of intraluminal thrombus on abdominal aortic aneurysm as assessed by a new non-invasive method.

Intraluminal thrombus may play a role in abdominal aortic aneurysm pathogenesis and rupture. The purpose of this work was to demonstrate the feasibility of a new non-invasive method for the determination of the biomechanical features of the aortic wall and luminal boundary in abdominal aortic aneurysm containing intraluminal thrombus. Automated ultrasonographic measures of infrarenal aortic cross-sectional area (A) were obtained on-line along with non-invasive arterial pressure (p) from eight patients of mean (s.e.m.) age 74(3) years, with abdominal aortic aneurysm (mean dimensions 5.9(0.4) x 5.3(0.5) cm) containing intraluminal thrombus. Luminal boundary and abdominal aortic aneurysm wall were scanned separately. Compliance (C) was computed as C = (Amax - Amin)/[Amax(Pmax - Pmin)], where 'max and 'min' represent maximum and minimum values, respectively. Mean compliance was lower for the abdominal aortic aneurysm wall alone than for the luminal surface enclosed by intraluminal thrombus: 4.0(0.9) x 10(-4)/mmHg versus 9.8(1.7) x 10(-4)/mmHg (P < 0.01). Intraluminal thrombus area was nearly constant over the cardiac cycle, indicating that the thrombus is virtually incompressible. This noninvasive method to assess biomechanical features of abdominal aortic aneurysm has potential to further the understanding of the influences of intraluminal thrombus on aneurysm disease.

Aged↗
PubMed1995

Changes in electrocardiographic morphology reflect instantaneous changes in left ventricular volume and output in cardiac surgery patients.

We examined the relation between changes in R-to-T wave amplitude ratios (R:T) and left ventricular (LV) performance as cardiac output was rapidly varied by inferior vena caval occlusion in 6 subjects prior to cardiopulmonary bypass. To assess the influence of contractility, paired studies before and after bypass were performed in 4 subjects. Stroke volume and cardiac output were assessed by aortic flow probe, and transesophageal echocardiographic LV area measures using the automated border-detection method were used to give LV stroke area, stroke force, maximal LV area, fractional area change, end-systolic elastance, and preload recruitable stroke force. Data were collected on computer and analyzed by linear regression. Significant changes in R:T and measured LV variables during the inferior vena caval occlusion were stroke volume (r = 0.81), LV stroke area (r = 0.77), LV stroke force (r = 0.81), maximal LV area (r = 0.78), and cardiac output (r = 0.80). However, R:T varied inconsistently in relation to fractional area change. After cardiopulmonary bypass, the linear relation between R:T with LV stroke force, LV stroke volume, and maximal LV area persisted, but at a lesser slope. Although absolute pre-inferior vena caval occlusion R:T did not correlate with end-systolic elastance or preload recruitable stroke force, the change in the slope of these linear relations correlated well with the change in end-systolic elastance after surgery (r = 0.92). Instantaneous changes in electrocardiographic morphology reflect changes in LV preload-dependent variables, whereas long-term changes in electrocardiographic morphology may also reflect changes in contractile state.

Aged↗
PubMed1995

Automated echocardiographic measures of right ventricular area as an index of volume and end-systolic pressure-area relations to assess right ventricular function.

BACKGROUND: On-line determination of right ventricular (RV) volume to assess its function is clinically difficult. Echocardiographic automated border detection measures of left ventricular (LV) cavity area have been shown to reflect changes in volume, and pressure-area relations have been used to estimate LV contractility. The potential for RV cavity area to estimate changes in volume and to assess RV function, however, has not been evaluated. Accordingly, the objective of this study was to determine the relation between echocardiographic automated border-detected RV cross-sectional area and true volume and to assess the potential for end-systolic pressure-area relations to estimate RV function in an isovolumically contracting isolated canine heart preparation. METHODS AND RESULTS: Eight excised dog hearts with both right and left intraventricular balloons were perfused in an ex vivo apparatus in which both ventricular volumes were controlled independently. RV area data from the level of the left midventricular short-axis plane and pressure data were recorded on a computer through a customized hardware and software interface with the ultrasound system. RV volumes were varied from 9.4 +/- 3.9 to 43.8 +/- 6.9 mL at each of three different LV volume ranges (low range, 12.5 +/- 3.8 mL; medium range, 23.9 +/- 5.6 mL; and high range, 37.5 +/- 5.4 mL). The variation of RV area during isovolumic contraction, which we called deformational area change, was considerable (1.49 +/- 0.68 cm2 mean +/- SD) but did not change significantly with changing RV and LV volumes. Linear regression analysis correlated the maximum, minimum, and mean automated border-detected RV area during isovolumic contraction with absolute volume. A predominantly linear relation was observed, with the group mean r = .98 (y = 0.16x + 0.97; SEE = 0.21 cm2). The effect of LV volume on RV area-volume relation was a significant parallel downward shift (P < .05) by increases in LV volume. End-systolic pressure-area and pressure-volume relations using simultaneously RV pressure were both highly linear and covaried with changing LV volume. CONCLUSIONS: Echocardiographic automated border-detected RV area reflects changes in RV volume under a constant LV volume, and the derived end-systolic pressure-area relation has potential for on-line assessment of RV function.

Animals↗
PubMed1995

Transesophageal echocardiography to evaluate patients with severe pulmonary hypertension for lung transplantation.

The surgical approach to lung transplantation for patients with severe pulmonary hypertension will be dependent on the primary disease and specific cardiac anatomy. To determine the safety and utility of transesophageal echocardiography in the management of patients with severe pulmonary hypertension who are being evaluated for lung transplantation, we studied 48 consecutive patients, aged 38 +/- 11 years, with pulmonary artery systolic pressure of 70 mm Hg or greater. All patients previously underwent left and right heart catheterization, transthoracic echocardiography, and radionuclide ventriculography. Transesophageal echocardiography was tolerated well by all patients. Additional data that significantly altered surgical therapy was found in 12 of 48 patients (25%): proximal pulmonary artery thrombi (3), patent foramen ovale with significant right to left shunting (2), atrial septal defect (2), double-outlet right ventricle (2), ventricular septal defect (2), and exclusion of atrial septal defect (1). These findings were confirmed surgically in all patients except 3, who died awaiting transplantation. Transesophageal echocardiography is useful in the evaluation of patients with severe pulmonary hypertension.

Adult↗
PubMed1995

Hemodynamic effects of pyruvate infusion in dogs.

PURPOSE: Although pyruvate supplementation enhances endurance in humans and increases cardiac output in dogs, its effects on cardiac and peripheral vascular function are not known. Thus, we assessed the cardiovascular effects of pyruvate infusion. MATERIALS AND METHODS: Aortic, left ventricular (LV), and pulmonary (Ppa) pressures and LV stroke volume (Svlv; derived from aortic flow probe) were measured after thoracotomy in eight anesthetized dogs. LV area or volume changes were measured using either an epicardial echocardiography (n = 6) or a conductance catheter (n = 2). LV end-systolic elastance (Eeslv) and preload recruitable stroke force (PRSFlv) relations, as estimates of contractility, were generated by transient inferior vena cava occlusion. Simultaneous stroke volume to arterial pressure relations during the occlusions were used to measure arterial elastance (Ea), and steady-state systemic and pulmonary vascular resistances were used as measures of arterial tone. Graded doses of pyruvate (8, 16, and 32 mg/kg/min), dobutamine (positive control) and propranolol (negative control) and placebo (volume control) were sequentially given. RESULTS: Dobutamine increased Eeslv, PRSFlv, whereas propranolol had the opposite effect on Eeslv and PRSFlv. Pyruvate at 32 mg/kg/min increased heart rate, Ppa, and SVlv and decreased LV end-diastolic area, and systemic vascular resistance without changing arterial pressure, Eeslv, PRSFlv, or Ea. CONCLUSIONS: We conclude that pyruvate infusion in normal dogs induces venodilation but does not alter either cardiac contractility or arterial tone.

Animals↗
PubMed1994

A system for the on-line acquisition, visualization, and analysis of pressure-area loops.

Transesophageal echocardiography is a widely accepted technique for the assessment of left ventricular (LV) function in the operating room, intensive care unit, and cardiac catheterization suite. Not only do the images generated by these systems provide the observer with dynamic views of currently ongoing cardiac mechanics, but the computed LV area values obtained by the automated border detection system can be converted to an analog signal and then used to generate pressure-area loops if LV pressure is measured simultaneously. The intraventricular area has been shown to correlate closely with intraventricular volume and to vary proportionately. Therefore, it can be substituted for volume to generate pressure-area loops that display equivalent behavior to external perturbations as pressure-volume loops. Visualization of these waveforms and the values extracted from them, along with the associated hemodynamic values, provide valuable insight into ventricular function and heart-lung interactions. This paper describes a system that was designed and developed to acquire, display, store, and analyze pressure-area loops in addition to other associated hemodynamic signals of interest.

Computer Systems↗
PubMed1994

Estimation of left ventricular compliance using on-line echocardiographic automated border detection and pressure data.

The end-diastolic pressure-volume relationship can be used to describe left ventricular (LV) compliance. The objective of this study was to utilize measurements of LV cavity area by echocardiographic automated border detection and pressure data to estimate the end-diastolic pressure-volume curve in an isolated heart preparation where true volume could be measured by an intraventricular balloon. Six dog hearts were excised for placement of an intraventricular balloon and a micromanometer catheter and perfused in an ex vivo circuit. Mid-ventricular short-axis images were used to measure cross-sectional area by automated border detection while LV volumes were increased from 5 ml to maximal volume (30-40 ml) in each preparation. Simultaneous area and pressure data were recorded on a computer workstation through a customized interface with the ultrasound system. Three runs of varying LV volumes at 1 ml increments were performed on each of 6 hearts for a total of 1,080 simultaneous measurements. Pressure-volume and pressure-area curves were analyzed by linear regression analyses, the slope of which was used to estimate compliance. End-diastolic pressure-area and pressure-volume relationships were significantly correlated with mean r = 0.97 +/- 0.02 (p < 0.001) from individual hearts. The slopes which served to estimate compliance of the individual pressure-area and pressure-volume curves were similar and differed by only 7 +/- 4%. A similar correlation was observed by second order regression analyses with r = 0.97 +/- 0.01 (p < 0.001) for pressure-area and r = 0.98 +/- 0.01 (p < 0.001) for pressure-volume relationships.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Utility and limitations of biplane transesophageal echocardiographic automated border detection for estimation of left ventricular stroke volume and cardiac output.

Recent echocardiographic ABD algorithms can estimate LV volume on-line from a single long-axis plane. The objective of this study was to assess the capability and limitations of transesophageal ABD to estimate stroke volume and cardiac output in patients before and after coronary artery bypass surgery by correlating these data with simultaneous thermodilution measurements. ABD data were acquired on-line from the transverse-plane four-chamber view and the longitudinal-plane two-chamber view and calculated by automated area-length and Simpson's rule formulas for volume. Thirty-three studies were attempted in 18 patients. Technically adequate ABD data were available in all patients from at least one view. Twenty-two (67%) of 33 studies from the four-chamber view and 27 (82%) of 33 studies from the two-chamber view were technically adequate. Cardiac output by all ABD methods was significantly correlated with thermodilution values (r range 0.72 to 0.89; SEE range 0.48 to 0.55 L/min). The two-chamber view underestimated cardiac output slightly, by an average of 0.4 L/min, whereas the four-chamber view consistently underestimated cardiac output by an average of 1.9 L/min. The area-length and Simpson's rule algorithms produced similar results. Biplane transesophageal ABD is an alternative method for estimating cardiac output; the two-chamber view in particular has potential for on-line volume determination.

Adult↗
PubMed1994

Assessment of left ventricular performance by on-line pressure-area relations using echocardiographic automated border detection.

OBJECTIVES: The purpose of this study was to evaluate left ventricular performance by on-line pressure-area relations using echocardiographic automated border detection in the in situ canine heart in a manner similar to pressure-volume analyses. BACKGROUND: Echocardiographic automated border detection can measure ventricular cavity area as an index of volume and may be interfaced with pressure to construct pressure-area loops on-line. METHODS: Eight anesthetized open chest dogs had simultaneous measurement of ventricular pressure, aortic flow and midventricular short-axis area. Pressure-area loops were constructed by a computer workstation interfaced with the ultrasound system. Stroke area (Maximal area--Minimal area) and stroke force (integral of P dA [P = pressure; A = area]) values during inferior vena cava (n = 8) and aortic (n = 4) occlusions were compared with stroke volume and estimates of stroke work, respectively. Inotropic modulation was induced with dobutamine infusion (2 to 5 micrograms/kg body weight per min), followed by propranolol infusion (2 to 5 mg). End-systolic and maximal elastance and preload recruitable stroke force (stroke force versus end-diastolic area) were derived for each period. RESULTS: Changes in stroke area and stroke force were significantly correlated with changes in stroke volume and estimates of stroke work during caval occlusion (n = 8) (r = 0.87 +/- 0.02, SEE = 8 +/- 1% and r = 0.90 +/- 0.03, SEE = 8 +/- 2%, respectively). In dogs with aortic occlusion (n = 4), changes in stroke area significantly correlated with changes in stroke volume for pooled data (r = 0.84, SEE = 8%, y = 1.0x + 3). Ventricular performance increased with dobutamine infusion (n = 7): end-systolic elastance 30 +/- 11 to 67 +/- 24 mm Hg/cm2 (p < 0.02 vs. control values); maximal elastance 37 +/- 11 to 82 +/- 26 mm Hg/cm2 (p < 0.02 vs. control values); preload recruitable stroke force 81 +/- 24 to 197 +/- 92 mm Hg (p < 0.02 vs. control values). Decreases occurred with propranolol infusion (n = 5) end-systolic elastance 20 +/- 4 to 13 +/- 4 mm Hg/cm2 (p < 0.002 vs. control values); maximal elastance 29 +/- 8 to 15 +/- 5 mm Hg/cm2 (p < 0.002 vs. control values); preload recruitable stroke force 66 +/- 14 to 40 +/- 9 mm Hg (p < 0.002 vs. control values). CONCLUSIONS: On-line pressure-area relations are a potentially useful means to assess left ventricular performance in a manner that is quantitatively similar to the predicted responses of pressure-volume relations.

Animals↗
PubMed1994

Rapid estimation of left ventricular contractility from end-systolic relations by echocardiographic automated border detection and femoral arterial pressure.

BACKGROUND: Automated echocardiographic measures of left ventricular (LV) cavity area are closely correlated with changes in volume and can be coupled with LV pressure to construct pressure-area loops in real time. The objective was to rapidly estimate LV contractility from the end-systolic relations of cavity area (as a surrogate for LV volume) and femoral arterial pressure (as a surrogate for LV pressure) in patients undergoing cardiac surgery. METHODS: Studies were attempted on 18 consecutive patients with recordings of LV pressure, LV area, and femoral arterial pressure on a computer workstation interfaced with the ultrasound system. End-systolic pressure-area relations (in terms of pressure-area elastance [E'es]) from pressure-area loops during inferior vena caval occlusions were determined before and immediately after cardiopulmonary bypass using both LV and arterial pressure by semiautomated and automated iterative linear regression methods. RESULTS: Data sets were available for 13 patients before and 8 patients after bypass (21 studies in 14 patients). E'es by arterial pressure was closely correlated with E'es by LV pressure: r = 0.96, standard error of the estimate = 2 mmHg/cm2, y = 1.01 x -0.7 by the semiautomated method and r = 0.94, standard error of the estimate = 3 mmHg/cm2, y = 1.02 x -0.5 by the automated method. Analysis of semiautomated and automated estimates of E'es from arterial pressure and E'es using LV pressure by the Bland-Altman method showed no systematic measurement bias and calculated limits of agreement of 8 and 9 mmHg/cm2, respectively. Similar decreases in E'es by arterial and LV pressure occurred from before to after bypass in 7 patients with paired data sets: 32 +/- 12 to 15 +/- 6 mmHg/cm2 and 32 +/- 15 to 15 +/- 7 mmHg/cm2, respectively (P < 0.05 for both). CONCLUSIONS: On-line femoral arterial pressure and LV area data by echocardiographic automated border detection may be used to rapidly calculate E'es as a means to estimate LV contractility in selected patients.

Adult↗