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Biomedical subjects

B J Rubal

Publications and source records attributed to B J Rubal.

49 records · Page 3Linked to original sources
PubMed1986

Hemodynamic response to rapid pneumatic antishock garment deflation.

Irreversible hypotension with subsequent cardiovascular collapse has been reported as a catastrophic complication of inappropriate pneumatic antishock garment (PASG) deflation. This study was undertaken to analyze the cardiodynamic response by which PASG deflation produces hypotension. Five normovolemic patients undergoing cardiac catheterization for atypical chest pain syndrome volunteered for this study. Serial measurements of right atrial, right ventricular, pulmonary artery, left ventricular, and aortic pressures were obtained with subjects supine at the following times: prior to inflation of the PASG; during PASG inflation at 100 mm Hg; and during rapid PASG deflation. Pulmonary and aortic flow velocities were recorded in two patients. The application of external pressure with PASG produced a significant increase in left and right heart pressures (P less than .05). Sudden PASG deflation produced significant transient hypotensive changes (P less than .01). When PASG deflation hemodynamics were compared to preinflation data, mean arterial pressure decreased 14 mm Hg (P less than .01); mean pulmonary pressure decreased 6 mm Hg (P less than .01); and mean right atrial and left ventricular end-diastolic pressures decreased 4 and 6 mm Hg, respectively (P less than .01). An analysis of right and left heart hemodynamic data suggests that the early hypotensive response associated with PASG deflation is consistent with a reduction in left ventricular afterload followed by a decrease in preload.

Adult↗
PubMed1986

Left ventricular performance of the athletic heart during upright exercise: a heart rate-controlled study.

This study compares the left ventricular performance of chronically conditioned pentathletes (N = 10) with less-conditioned subjects (N = 10) during dynamic upright exercise. The pentathletes were found to have a superior treadmill performance [24 +/- 4 vs 17 +/- 2 min (SD), P less than 0.01], reduced resting heart rate (41 +/- 13 vs 62 +/- 6 bpm, P less than 0.01), and increased left ventricular mass (254 +/- 85 vs 179 +/- 35 g, P less than 0.05) compared to the control group. Radionuclide ventriculography and heart rate controlled-bicycle ergometry were employed to examine changes in left ventricular ejection fraction, end-diastolic volume, end-systolic volume, and stroke volume. Heart rate was controlled by adjusting the resistance of the ergometer until stable heart rates of 90, 110, 130, and 150 bpm were achieved. Following heart rate stabilization, 99mTc images were acquired during 3-min stages at each target heart rate level. In the pentathletes, left ventricular ejection fraction, end-diastolic volume, and stroke volume increased (P less than 0.01) during exercise, and end-systolic volume tended to decrease. No difference was noted in left ventricular ejection fraction between groups when heart rates were matched. However, the exercise-induced changes in end-diastolic volume and stroke volume were greater (P less than 0.01) in the pentathletes. In conclusion, the athletes studied relied on the same mechanism as the less-conditioned subjects for improving pump performance during exercise stress, but the athletes' ability to mobilize a greater end-diastolic volume accounts for their larger stroke output during each stage of heart rate-matched exercise.

Adult↗
PubMed1986

Supplemental chloralose anesthesia in morphine premedicated dogs.

This study evaluated the cardiorespiratory stability of six dose-regulated, 12-hour, chloralose anesthetic maintenance protocols. Thirty mongrel dogs were premedicated with morphine sulfate (5mg/kg) and anesthetized with an induction dose of chloralose (80mg/kg). Fifteen animals were permitted to breathe spontaneously and 15 animals were ventilated mechanically to maintain a constant arterial pCO2 (40 +/- 5 mmHg). The spontaneously breathing dogs were separated into three groups in which animals (n = 5) were given different bolus doses of supplemental anesthetic. Initially the spontaneously breathing animals were hypoxemic, acidemic and hypercapnic. No consistent hemodynamic difference was noted among these groups. The mechanically ventilated animals were also divided into three groups that received varying doses of supplemental chloralose by constant infusion. Significant (p less than 0.01) myocardial depression was noted in the heavy-dosed animals by the third hour. Systolic pressure decreased 44%, pulse pressure decreased 37% and peak left ventricular dP/dt decreased 52%. All heavy-dosed animals expired before the eighth hour. Although these data suggest that morphine-premedicated, chloralose-anesthetized animals generally provide a stable cardiopulmonary model, high-dose chloralose supplementation depressed ventilation and produced a dose-dependent cardiotoxicity.

Anesthesia↗
PubMed1985

Regional wave travel and reflections along the human aorta: a study with six simultaneous micromanometric pressures.

The human aorta and its terminal branches were investigated in normal subjects during elective cardiac catheterization to evaluate regional wave travel and arterial wave reflections. A specially designed catheter with six micromanometers equally spaced at 10 cm intervals was positioned with the tip sensor in the distal external iliac artery and the proximal sensor in the aortic arch. Simultaneous pressures were obtained and analyzed for foot-to-foot wave velocity, and Fourier analysis was used to derive apparent phase velocity. These quantities were assessed during control (n = 9), during Valsalva (n = 8) and Müller (n = 4) maneuvers, and during femoral artery occlusion by bilateral manual compression (n = 8). During control, regional cross-sectional areas, determined from aortography, and regional foot-to-foot pulse wave velocities were used to calculate the local reflection coefficient in the proximal descending aorta (gamma = 0.05), at the junction of the renal arteries (gamma = 0.43), and at the terminal aortic bifurcation (gamma = 0.13). To test the hypothesis that significant reflections originate in the aorta, at the level of the renal arteries, aortograms were used to design a latex tube model with geometric properties similar to the descending aorta. Velocities and reflection characteristics in the model and in vivo were compared. Inspection of thoracic aortic pressures under control conditions revealed a reflected wave originating from the region of the aorta at the level of the renal arterial branches while abdominal pressures exhibited reflection from a site peripheral to the terminal aortic bifurcation. In the low frequency range, apparent phase velocity was found to be higher proximal to the renal arteries as compared with at the distal sites. In addition, the minimum value occurred at a higher frequency in the lower thoracic aorta than at more distal sites. The effects of reflection on apparent wave velocity in the tube model were consistent with data obtained in vivo. The Valsalva maneuver diminished the reflection from the aortic region of the renal arteries, thus allowing the distal reflected wave to become more evident on the thoracic pressure waveforms. Bilateral femoral artery occlusion usually enhanced the distal reflection and the Müller maneuver usually resulted in small increases in reflections. In conclusion, the geometric and elastic nonuniformity of the aorta results in two major sites of arterial wave reflection that influence the aortic pressure waveforms in man.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1985

Left ventricular volume determination from single-photon emission computed tomography.

To compare the accuracy of single-photon emission computed tomography (SPECT) with that of contrast cineangiography in measuring left ventricular end-diastolic volume, 25 consecutive patients undergoing catheterization for coronary artery or valvular heart disease were first evaluated scintigraphically. A simple, count-corrected voxel counting technique was used to derive left ventricular end-diastolic volume from transaxial SPECT slices. SPECT volume values showed a high degree of correlation with those determined by angiography (r = 0.969), with a standard error of the estimate of 23 ml. SPECT offers a highly accurate and essentially noninvasive method for measuring chamber volumes that is independent of geometric assumptions about ventricular configuration and chest wall attenuation and does not require blood sample counting.

Adult↗
PubMed1984

Left atrial myxoma: phonocardiographic, echocardiographic, and micromanometric hemodynamic correlations.

We used simultaneous echocardiography, phonocardiography, and high-fidelity micromanometry to investigate the impact of the movement of a large pedunculated left atrial myxoma on hemodynamics. The case we have described shows that (1) the early diastolic sound (tumor plop) coincided with maximal excursion of the tumor in the left ventricular inflow tract, (2) tumor movements during mid to late diastole corresponded to low-frequency oscillations in left ventricular pressure, (3) tumor expulsion from the left ventricle into the left atrium was initiated during "isovolumic" contraction but continued into the early ejection phase, (4) mitral valve closure was abnormally delayed until after the onset of aortic ejection, and (5) systolic ejection was initiated before coaptation of the mitral valve leaflets. These findings support the theory that tumor motion contributes to both systolic and diastolic vibrations of the entire cardiohemic system.

Aged↗
PubMed1982

Liquid crystal thermography. A new tool for evaluating low back pain.

Liquid crystal thermography was used to determine low back skin temperature patterns in 62 patients hospitalized for low back pain and 22 college volunteers with no previous history of back pain. The patients were separated into four groups according to their diagnoses at discharge: patients with 1) degenerative discogenic lesions, 2) acquired lesions, 3) congenital and developmental lesions, 4) back pain resulting from unknown causes. No significant differences were found between the average equilibrated thermogram temperatures of the control subjects (32.4 +/- 0.5 degrees C) and patient groups. However, the temperature gradients found on the thermograms of patients with discogenic lesions (3.1 +/- 0.6 degrees C) and acquired lesions (3.1 +/- 1.0 degrees C) were significantly greater (p less than .05) than those of the pain-free subjects (2.5 +/- 0.5 degrees C). Tenderness to palpation was associated with elevated skin temperatures in 80 percent of the patients studied. This study suggests that liquid crystal thermography may be a potentially useful tool for localizing soft tissue trauma in patients with low back pain.

Adult↗
PubMed1981

Echocardiographic examination of women collegiate softball champions.

The cardiac profile of nine AIAW softball champions (SC) was compared with the cardiac profile of 10 sedentary women who were matched according to age and body size (SW). Standard M-mode echocardiography and a maximum graded stress test were performed on each subject. The mean (+/- SE) resting heart rate (50.6 +/- 2.6 bpm) and VO2max (55.3 +/- 2.0 ml O2 x kg-1 x min-1) of the SC were significantly different (P less than 0.001) than the heart rate (71.2 +/- 3.1 bpm) and VO2max (40.3 +/- 1.4 ml x kg-1 x min-1) of the SW. Significantly greater (P less than 0.05) interventricular septal thickness (IST), and left ventricular end-diastolic dimension (LVIDd) and volume (LVIDd3) were noted in the SC. The means (+/- SE) for IST, LVIDd, and LVIDd3 for the athletes were 8.9 +/- 0.4 mm, 4.8 +/- 0.1 cm, and 110 +/- 5.9 cm3, respectively; and for the SW were 7.5 +/- 0.5 mm. 4.4 +/- 0.2 cm, and 87.8 +/- 8.0 cm3, respectively. Although there was no difference in the left ventricular cavity/muscle volume ratio, the athletes had an increased (P less than 0.02) left ventricular mass (168 +/- 15 g) when compared with SW (123 +/- 9 g). Therefore, the cardiac adaptations noted during rest in moderate-endurance trained AIAW softball champions included a relative bradycardia and eccentric hypertrophy.

Adult↗
PubMedDate not supplied

Pharmacodynamic Doppler determination of mitral valve area in patients with significant aortic regurgitation.

In patients with combined mitral stenosis (MS) and aortic regurgitation (AR), the Doppler-determined mitral valve area (MVA) may be overestimated due to a shorter than expected pressure half-time. We performed Doppler echocardiography at baseline and after inhalation of amyl nitrite in 10 patients with combined MS and AR (Group I) and in five patients with MS alone (Group II). AR severity was reduced by amyl nitrite inhalation in all Group I patients, with a decrease in mean jet height/LVOT ratio from 32% to 21% (p < 0.01). Pressure half-time increased in Group I after amyl nitrite, with a mean reduction in the calculated MVA of 0.15 cm2 (p < 0.01). Group II had no significant changes in pressure half-time or Doppler-determined MVA after amyl nitrite, whereas both groups had comparable increases in heart rate, mean transmitral velocity, and mean transmitral pressure gradient. In patients with combined MS and AR, we conclude that amyl nitrite significantly increases pressure half-time while reducing the severity of AR. These findings support earlier reports of MVA overestimation when pressure half-time is used in the presence of AR.

Adult↗