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Biomedical subjects

J Gorcsan

Publications and source records attributed to J Gorcsan.

At least 55 records · Page 3Linked to original sources
PubMed1994

A potential role for nitric oxide in myocardial stunning.

Nitric oxide (NO) production by the human heart has been demonstrated in patients undergoing cardiac surgery. Similar to what has been described in other species, a basal production of NO by the human heart is seen (126 +/- 42 pmol/min per gram). Following reperfusion, at the end of the procedure, the level of NO production increases significantly reaching concentrations of 1430 +/- 330 pmol/min per gram. Increased activity for the enzyme NO synthase (NOS) (8.0 +/- 1.2 pmol/mg prebypass vs 26.4 +/- 4.8 pmol/mg postbypass) coincides with changes in NO production and occurs at a time when myocardial stunning is clinically detectable. The significance of these findings is discussed and suggest a role for NO in the pathophysiology of myocardial stunning.

Amino Acid Oxidoreductases↗
PubMed1994

Assessment of the immediate effects of cardiopulmonary bypass on left ventricular performance by on-line pressure-area relations.

BACKGROUND: Pressure-volume relations have been established as useful measures of left ventricular (LV) performance. Application of these methods to the intraoperative setting have been limited because of difficulties acquiring LV volume data. Transesophageal echocardiographic automated border detection can measure LV cross-sectional area as an index of volume, which can be coupled with pressure data to construct pressure-area loops on-line. The purpose of this study was to evaluate intraoperative LV performance in patients undergoing coronary bypass surgery before and immediately after cardiopulmonary bypass using on-line pressure-area relations. METHODS AND RESULTS: Studies were attempted in 13 consecutive patients. Simultaneous measures of LV cross-sectional area, LV pressure, and electromagnetic flow probe-derived aortic flow recorded on a computer work station interfaced with the ultrasound system. Pressure-area loops were compared with simultaneous pressure-volume loops constructed from pressure and flow data during inferior vena caval occlusions before and after bypass. Pressure-volume calculations (end-systolic elastance, maximal elastance, and preload-recruitable stroke work) were then applied to pressure-area loops with area substituted for volume data. Changes in stroke force from pressure-area loops were closely correlated with changes in estimates of stroke work from pressure-volume loops for individual patients before bypass (r = .99 +/- .03, SEE = 5 +/- 2%, n = 10) and after bypass (r = .96 +/- .05, SEE = 5 +/- 2%, n = 9). Pressure-area estimates of end-systolic elastance, maximal elastance, and preload-recruitable stroke force decreased significantly from before to after cardiopulmonary bypass in the 7 patients with paired data sets. Load-dependent measures of LV function (stroke volume, cardiac output, and fractional area change) were unchanged after surgery in these same patients. CONCLUSIONS: Intraoperative pressure-area loops may be acquired and displayed on-line using transesophageal echocardiographic automated border detection and readily analyzed in a manner similar to pressure-volume loops. LV performance was depressed immediately after cardiopulmonary bypass compared with before. On-line pressure-area relations may be clinically useful to assess LV performance in patients undergoing cardiac surgery in whom load and contractility may be expected to vary rapidly.

Aged↗
PubMed1994

Reversible diastolic dysfunction after successful coronary artery bypass surgery. Assessment by transesophageal Doppler echocardiography.

To assess the potential effects of coronary artery bypass surgery on left ventricular diastolic filling, 12 patients, aged 65 +/- 11 years, were studied by serial transesophageal Doppler echocardiograms. Doppler measures of mitral inflow velocity were made before, immediately after, 4 h after, and 20 h after cardiopulmonary bypass (CPB). Left atrial pressure was directly measured and controlled at 10 +/- 2 mm Hg for each study period. Mitral maximal early inflow velocity (E)/maximal atrial velocity (A) ratios and atrial filling fractions were calculated as indexes of diastolic function from maximal E and A velocities and their time velocity integrals, respectively. Data sets were available for serial comparison in 11 patients and were also compared with an age-matched control group of normal values. The results of E/A ratios were as follows: control group--1.4 +/- 0.2; before CPB--1.7 +/- 0.6; immediately after CPB--1.0 +/- 0.2 (p < 0.05 vs control group, before CPB, and 20 h after CPB values); 4 h after CPB--0.8 +/- 0.2 (p < 0.05 vs control group, before CPB, and 20 h after CPB values); and 20 h after CPB--1.3 +/- 0.4. Atrial filling fractions were as follows: control group--0.29 +/- 0.05; before CPB--0.25 +/- 0.06; immediately after CPB--0.43 +/- 0.07 (p < 0.05 vs control group, before CPB, and 20 h after CPB values); 4 h after CPB, 0.46 +/- 0.07 (p < 0.05 vs control group, before CPB, and 20 h after CPB values); and 20 h after CPB--0.35 +/- 0.06. Alterations in Doppler indexes of left ventricular filling occurred immediately after CPB and persisted 4 h after CPB. These indexes returned to baseline values by 20 h after CPB. This suggests reversible diastolic dysfunction in patients after coronary artery bypass surgery.

Adult↗
PubMed1993

Comparison of left ventricular function by echocardiographic automated border detection and by radionuclide ejection fraction.

Echocardiographic automated border detection can provide on-line estimates of left ventricular cavity area by differentiating blood from tissue backscatter characteristics. The objective of this study was to assess the ability of short-axis measurements of left ventricular cavity area by automated border detection to determine left ventricular function by comparing these measurements to radionuclide measures of ejection fraction in the same patients. Eighty-eight consecutive patients, aged 53 +/- 14 years, underwent automated border detection studies within 2 hours of radionuclide ventriculography. Short-axis imaging with automated border detection was attempted at basal, midpapillary muscle, and apical levels. Maximal left ventricular length was also measured from apical 4- and 2-chamber views by standard imaging. Fractional area change--(end-diastolic area-end-systolic area)/end-diastolic area--was determined at each short-axis level. Volumes and ejection fractions were calculated using: volume = 5/6 (midventricular area).length. Simpson's rule for 3 short-axis measurements was calculated using: volume = (length/12) (5.basal area + 2.mid-area + 4.apical area). Technically adequate automated border detection data could be obtained on 69 patients (78%) at basal and mid-levels, and at all 3 short-axis levels in 66 patients (75%). Correlations with radionuclide ejection fraction were as follows: midventricular fractional area change--R = 0.84, SEE = 12%, y = 0.86 x - 7; area-length ejection fraction--R = 0.89, SEE = 9%, y = 0.96 x - 4; and Simpson's rule--R = 0.91, SEE = 8%, y = 0.89 x + 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

On-line estimation of changes in left ventricular stroke volume by transesophageal echocardiographic automated border detection in patients undergoing coronary artery bypass grafting.

Echocardiographic automated border detection can determine the interface between blood and myocardial tissue and calculate left ventricular (LV) cavity area in real-time. The objective was to determine if on-line measurements of LV cavity area by transesophageal automated border detection could be used to determine beat-to-beat changes in stroke volume in humans. Studies were attempted on 9 consecutive patients, aged 66 +/- 8 years, undergoing coronary bypass surgery. Stroke volume was measured by electromagnetic flow from the ascending aorta, and LV cavity area was measured at the midventricular short-axis level. Simultaneous area and flow data were recorded on a computer workstation through a customized interface with the ultrasound system. Recordings were performed during baseline apnea and rapid alterations induced by inferior vena caval occlusions before and after cardiopulmonary bypass. Measurements of stroke area (maximal area-minimal area) were correlated with stroke volume for matched beats. Data were available for analysis on 8 of 9 patients before and on 5 patients after cardiopulmonary bypass for 644 beats. Stroke area was closely correlated with stroke volume both before (mean R = 0.94 +/- 0.03, SEE = 0.33 +/- 0.12 cm2) and after (mean R = 0.92 +/- 0.05, SEE = 0.59 +/- 0.81 cm2) cardiopulmonary bypass. The slopes of these stroke area-stroke volume relations were quite reproducible from before to after cardiopulmonary bypass in the same patient but varied between individual patients. Transesophageal automated border detection has potential for on-line estimation of changes in stroke volume in selected patients.

Aged↗
PubMed1993

Transgastric continuous-wave Doppler to determine cardiac output.

A new method to measure cardiac output using transgastric continuous-wave Doppler was evaluated in 31 consecutive patients undergoing cardiac surgery with simultaneous measurement of cardiac output by the thermodilution technique. A 5 MHz single-plane imaging/5 MHz continuous-wave Doppler transesophageal transducer was used to image the left ventricular outflow tract, aortic valve and ascending aorta from a modified transgastric short-axis plane. The continuous-wave Doppler cursor was aligned parallel with blood flow across the aortic valve to obtain the maximal Doppler velocity spectra. Stroke volume was obtained by multiplying the mean Doppler flow velocity integral by the aortic annulus area, which was calculated from its diameter measured from the esophageal 5-chamber view. The stroke volume was multiplied by heart rate to yield cardiac output. A total of 57 simultaneous thermodilution and Doppler studies were attempted. Doppler data were technically limited for 2 patients both before and after cardiopulmonary bypass and for 3 patients before cardiopulmonary bypass with a result of 50 adequate studies of 57 (88%) attempted. The Doppler-derived cardiac outputs were correlated with the simultaneous measurements of cardiac output by the thermodilution technique. Linear regression analysis revealed a close correlation with R = 0.91, SEE = 0.8 liter/min, and y = 1.01x + 0.2 (p < 0.001). In conclusion, transgastric continuous-wave Doppler across the aortic valve is a promising new technique that may be used in selected patients for accurate measurement of cardiac output.

Cardiac Output↗
PubMed1993

On-line estimation of stroke volume by means of echocardiographic automated border detection in the canine left ventricle.

Echocardiographic automated border detection (ABD) is a new on-line technique that can determine the interface between blood and myocardial tissue and calculate left ventricular (LV) cavity area in real time. The objective of this study was to determine whether ABD measurements of the LV cavity area could be used to estimate LV stroke volume at basal conditions and during large changes in LV stroke volume induced by inferior vena caval occlusions in an open-chest canine model. Seven dogs had LV stroke volume measured by electromagnetic flow from the ascending aorta with epicardial recordings of ABD echocardiographic area at the midventricular short-axis level. Simultaneous beats of stroke volume were recorded along with ABD echo area during baseline apnea and during IVC occlusions. Neither ABD echo stroke area nor stroke volume varied significantly during apnea baseline. Changes in stroke area were closely correlated with changes in stroke volume for 540 matched beats from 24 IVC occlusions: R = 0.93, standard error of the estimate = 5%, y = 0.92x + 0.4 (p < 0.001). Echocardiographic ABD appears to be a promising new on-line method of determining rapid alterations in LV stroke volume; it also has potential applications to multiple investigational and clinical settings.

Animals↗
PubMed1993

Myocardial ischemia: a comparison between isoflurane and enflurane in coronary artery bypass patients.

Isoflurane may precipitate ischemia in patients with coronary artery disease, presumably via "coronary steal." We sought to examine whether myocardial ischemia is more common in patients with coronary artery disease receiving isoflurane (0.7%) than in a control group receiving enflurane (0.9%). Thirty-eight patients scheduled for coronary artery bypass surgery were randomly assigned one anesthetic and monitored for ischemia. All patients had ejection fractions of at least 45%. Extraneous causes of ischemia were controlled as much as possible: arterial blood pressure was maintained within 20% of baseline (primarily with phenylephrine), heart rate was maintained below 80 bpm, effects from endotracheal intubation were monitored, and measurements were made before incision. Electrocardiogram, transthoracic echocardiography, and coronary sinus lactate measurement were used to detect ischemia. Measurements were made after insertion of vascular catheters, after intubation, and after 20 min of breathing the inhaled anesthetic. During the awake period and after induction of anesthesia with fentanyl (25 micrograms/kg), there was no significant difference detected between the two groups in incidence of ischemia: 20% in the enflurane group and 22% in the isoflurane group (P = 0.38). After 20 min of receiving the inhaled anesthetic, the incidence of ischemia in the isoflurane group increased to 50%, whereas the incidence in the enflurane group was unchanged at 20% (P = 0.02). These results show that, even with strict control of hemodynamics, isoflurane is associated with more myocardial ischemia than is enflurane.

Aged↗
PubMed1992

Intraoperative determination of cardiac output by transesophageal continuous wave Doppler.

A new prototype transesophageal transducer with continuous-wave Doppler and pulsed Doppler capabilities was evaluated to calculate intraoperative cardiac output from the main pulmonary artery. Fifteen consecutive patients undergoing elective coronary artery bypass surgery were studied. The main pulmonary artery diameter above the pulmonic valve was measured with the single horizontal plane transesophageal transducer. The pulmonary artery cross-sectional area was calculated from its diameter using the formula: Area = 1/4 pi (diameter)2. Continuous-wave Doppler and pulsed Doppler spectra were recorded from the main pulmonary artery and their flow velocity integrals were then multiplied by pulmonary artery area and heart rate to yield cardiac output. The main pulmonary artery diameter could not be confidently measured in 2 of 15 patients (13%). In the remaining 13 patients, Doppler cardiac output measurements were correlated with simultaneous thermodilution measurements. The closest correlation with thermodilution cardiac output was with the continuous-wave Doppler cardiac output method: R = 0.91, SEE = 0.2 L/min, and y = 1.1x . 0.2 (p less than 0.001). The correlation of thermodilution with pulsed Doppler cardiac output was R = 0.83, SEE = 0.5 L/min, and and y = 0.86 + 1.0 (p less than 0.001). Transesophageal continuous-wave Doppler is a new technique that may be used in selected patients for accurate determination of intraoperative cardiac output.

Adult↗
PubMed1991

Noninvasive estimation of left atrial pressure in patients with congestive heart failure and mitral regurgitation by Doppler echocardiography.

A completely noninvasive method for estimating left atrial pressure in patients with congestive heart failure and mitral regurgitation has been devised with the use of continuous-wave Doppler echocardiography and brachial sphygmomanometry. Of 46 patients studied with mitral regurgitation, 35 (76%) had jets with distinct Doppler spectral envelopes recorded. The peak ventriculoatrial gradient was obtained by measuring peak mitral regurgitant velocity in systole and using the modified Bernoulli equation. This gradient was then subtracted from peak brachial systolic blood pressure, an estimate of left ventricular systolic pressure, to yield left atrial pressure (left atrial pressure = systolic blood pressure - mitral regurgitant pressure gradient). Noninvasive estimates of left atrial pressure from 35 patients were plotted against simultaneous recordings of mean pulmonary capillary wedge pressure resulting in the correlation y = 0.88x + 3.3, r = 0.88, standard error of estimate = +/- 4 mm Hg (p less than 0.001). Therefore, continuous-wave Doppler echocardiography and sphygmomanometry may be used in selected patients with congestive heart failure and mitral regurgitation for noninvasive estimation of left atrial pressure.

Atrial Function, Left↗
PubMed1990

Doppler echocardiographic evaluation of left ventricular diastolic function after percutaneous transluminal coronary angioplasty for unstable angina pectoris or acute myocardial infarction.

The effect of percutaneous transluminal coronary angioplasty (PTCA) on left ventricular (LV) diastolic function has not been systematically investigated in patients treated for unstable angina or ischemia after acute myocardial infarction (AMI). To assess the relation between reduction of stenosis severity and improvement in diastolic function in this setting, 42 patients with either unstable angina (n = 22) or post-AMI ischemia (n = 20) were serially monitored by Doppler echocardiography 8 +/- 5 hours before and 2 +/- 1 days after PTCA. Doppler LV filling indexes included isovolumic relaxation time, mitral deceleration time, E/A peak velocity ratio and atrial filling fraction. Eighteen aged-matched control subjects served to establish normal values for comparison. Before PTCA, both groups exhibited abnormal diastolic function demonstrated by prolonged isovolumic relaxation time and mitral deceleration time, decreased E/A ratio and increased atrial filling fraction. After PTCA isovolumic relaxation time and deceleration time decreased 18 +/- 28 (p less than 0.005) and 33 +/- 43 ms (p less than 0.002) in the unstable angina group and 18 +/- 23 (p less than 0.003) and 14 +/- 34 ms (difference not significant), respectively, in the post-AMI ischemia group. An increase in E/A ratio and a decrease in atrial filling fraction occurred in both groups; however, these changes were significant only in patients with post-AMI ischemia (+21%, p less than 0.03 and -11.4%, p less than 0.005, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Identification of a malpositioned atrial pacemaker lead across a patent foramen ovale by transesophageal echocardiography.

Transesophageal echocardiography was used for defining the unusual left atrial location of a malpositioned atrial pacemaker lead. This malpositioning occurred in a 75-year-old woman who had a small atrial septal aneurysm and a patent foramen ovale. Neither the precise location of the pacemaker lead tip nor the course of the lead was apparent by radiographic or transthoracic echocardiographic techniques. This report extends the potential utility of transesophageal echocardiography for the identification of malpositioned atrial pacemaker leads.

Aged↗
PubMedDate not supplied

Acquired right ventricular outflow tract obstruction after lung transplantation: diagnosis by transesophageal echocardiography.

Acute reduction in pulmonary pressures after lung transplantation for severe chronic pulmonary hypertension may produce a sudden decrease in cavity size of a hypertrophied right ventricle resulting in acquired right ventricular outflow tract obstruction. This case illustrates the utility of transesophageal echocardiography with continuous-wave Doppler to make a morphologic as well as hemodynamic diagnosis of acquired right ventricular outflow tract obstruction in a patient after lung transplantation.

Echocardiography↗
PubMedDate not supplied

Incomplete ventricular septal tear after blunt chest trauma: medical management with serial echocardiographic follow-up.

Incomplete ventricular septal tears are uncommon or probably underreported cardiac lesions caused by blunt chest trauma. This report describes two cases of incomplete ventricular septal tears that were not suspected clinically. Transthoracic and transesophageal echocardiography provided the diagnostic information in both of these cases. Despite associated valvular lesions, the patients' stable in-hospital course lead to the decision to treat them medically with no specific treatment to the incomplete ventricular septal tears. Accordingly, these two cases were observed for a mean period of 1.5 years with serial echocardiographic studies to track the natural history of these lesions. During the follow-up period, both of these cases did not manifest any changes in the extent of ventricular septal tear, septal structure, or any left-to-right shunting through the tear. There were no significant changes in left ventricular size, shape, or systolic function. Thus echocardiographic imaging proved to be useful both in initial diagnosis and follow-up.

Adolescent↗
PubMedDate not supplied

Two-dimensional echocardiographic automated border detection accurately reflects changes in left ventricular volume.

The objective of this study was to determine the relationship of on-line measurements of left ventricular cavity area generated by echocardiographic automated border detection to true volume measured by an intraventricular balloon in an isovolumically contracting isolated canine heart preparation. Seven excised dog hearts had placement of an intraventricular balloon and were perfused in an ex vivo apparatus. Left ventricular area data from the midventricular short-axis plane and pressure data were recorded on a computer through a customized hardware and software interface with the ultrasound system. Left ventricular volumes were varied from 5 ml to maximal values (30 to 40 ml) at 1-milliliter increments. Three increasing and decreasing volume ramps were analyzed on each of seven hearts for a total of 1260 simultaneous measurements. Linear regression analysis correlated mean automated border detection area with absolute volume from each preparation. A predominantly linear relationship was observed with an average correlation of r = 0.97 (y = 0.16x-0.69, SEE = 0.31 cm2, p < 0.01). Left ventricular area measures for six of seven dogs varied little during isovolumic contraction (< 0.4 cm2) but did show a systematic cardiac cycle-related variability in one dog (28% change in area, maximum to minimum, over all volumes). In conclusion, the relationship between cross-sectional area and left ventricular volume was predominantly linear and varied little during isovolumic contractions in the normal canine left ventricle. Echocardiographic automated border detection appears to be a promising method to reflect changes in left ventricular volume.

Animals↗