Search PubMed⌕ Search

Biomedical subjects

H Sandler

Publications and source records attributed to H Sandler.

At least 73 records · Page 4Linked to original sources
PubMed1977

Left ventricular mechanical efficiency in man with heart disease.

Thirty-eight adults with valvular and/or myocardial disease had heart catheterization with coronary blood flow and myocardial O2 consumption (MVO2) per 100 g measured by the nitrous oxide washout technique. Quantitative biplane angiocardiography was performed to assess left ventricular volume, mass, ejection fraction and work. Left ventricular efficiency was calculated from work, MVO2/100 g and mass. Efficiency ranged from 4 to 40% and was normal in some patients with severe ventricular pressure-volume work overloads. Total left ventricular MVO2 ranged up to 461 ml/min. Neither total MVO2 nor MVO2/100 g was significantly related to ventricular work, ejection fraction, or tension-time index. These data suggest 1) a relationship between left ventricular efficiency and myocardial function in chronic valvular or myocardial disease, 2) that efficiency may be normal in hypertrophied ventricles, and 3) that chronic increases in resting ventricular metabolic requirements are met by hypertrophy rather than by increased MVO2/100 g.

Adult↗
PubMed1977

Tolerance of females to +GZ centrifugation before and after bedrest.

Because women may be included as passengers in the proposed Space Shuttle System, this study was designed to investigate the +GZ tolerance of women and the possible degradation of this tolerance after a period of weightlessness as simulated by bedrest. Twelve healthy Air Force Flight Nurses served as test subjects. Over a 1-week period, each subject was exposed to +GZ levels starting at +2 GZ and increasing by 0.5 GZ increments to a gray-out point. This point was determined by peripheral vision loss with a standard lightbar and by reverse blood flow in the temporal artery. Ultimately, each woman was subjected to three runs at the +3 GZ level; each run was approximately 55 min long, separated by 5-min rest periods. Eight subjects with the best tolerance times were selected for 14 d of bedrest in a horizontal position; the other four were ambulatory controls. Tests before bedrest, immediately following, and 5 d later showed that average +GZ tolerance decreased by 67% after bedrest.

Adult↗
PubMed1976

Pulmonary damage following pulmonary microembolism in the dog. Effect of various types of treatment.

In the present study the pathogenesis of the pulmonary damage following infusion of thrombin in combination with a fibrinolysis inhibitor, AMCA, in the dog was elucidated. An important mechanism in the development of the pulmonary damage following infusion of thrombin and AMCA seems to be an increased vascular permeability in the pulmonary microvasculature leading to pulmonary oedema. The question whether this pulmonary damage can be prevented by antihistamine (mepyramine maleate), antiserotonins (methysergide, reserpine) antiprostaglandins (acetylsalicylic acid, indomethacin, polyphloretin phosphate), 'anti-inflammatory agents' (methylprednisolone, calcium) or an anti-adrenergic agent (phenoxybenzamine) was investigated. None of these agents did prevent the lung damage following thrombin and AMCA. In order to study the possible role of bronchoconstriction, the complement system and the kinin system for this damage dogs were also artificially ventilated with an increased end-expiratory pressure, decomplemented with cobra venom factor or treated with Trasylol respectively. Neither were these treatments effective in preventing the pulmonary damage. The findings of the present study suggest that the permeability increasing substance involved in the pathogenesis of the pulmonary damage following thrombin and AMCA is not histamine, serotonin, prostaglandins or bradykinin. Therefore another, still unknown factor, may be of greater importance for this damage.

Animals↗
PubMed1976

Cardiovascular function during sustained +Gz stress.

The development of aerospace systems capable of very high levels of positive (+Gz) stress, has created a need for a better understanding of the cardiovascular responses to acceleration. Using a canine model, the heart and cardiovascular system were instrumented to continuously measure coronary blood flow, cardiac output, left ventricular and aortic root pressure, and oxygen saturation in the aorta, coronary sinus, and right ventricle. The animals were exposed to acceleration profiles up to +6 Gz, 120 s at peak G; a seatback angle of 45 degrees was simulated in some experiments. Radiopaque contrast medium was injected to visualize the left ventricular chamber, coronary vasculature, aorta, and branches of the aorta. The results suggest mechanisms responsible for arrhythmias which may occur, and subendocardial hemorrhage which has been reported in other animals.

Blood Pressure↗
PubMed1975

A multichannel implantable telemetry system for flow, pressure, and ECG measurements.

The design of telemetry systems for chronic implantation within the body have progressed from simple single-channel devices to complex multichannel systems over the last 15 yr. Although chronic measurements of temperature, ECG, and pressure have been reported with good results, measurements such as dimension and blood flow have been difficult because of heavy power requirements. The design to be described is a multiplex system that will measure up to eight individual parameters simultaneously, including blood flow. Flow is measured using an electromagnetic transducer, and by special design, the normal high power requirements of the electromagnetic technique have been reduced to a few hundred milliwatts. The system is powered by two NiCad, rechargeable batteries which are periodically recharged through the intact skin by induction at 250 kHz to an implanted pickup coil. The presently constructed units have been configured to measure ECG, two pressures, temperature and ascending aortic flow.

Animals↗
PubMed1975

+Gz tolerance in man after 14-day bedrest periods with isometric and isotonic exercise conditioning.

The purpose of this study was to determine the effects of isometric or isotonic exercise training on post-bedrest +Gz tolerance. Seven male volunteers, 19-22 years, underwent accelerations of +2.1 Gz (740 s), +3.2 Gz (327 s), and +3.8 Gz (312 s) in a selected, randomized order; the ramp to peak acceleration was 1.8 G/min. The centrifugation runs were terminated by loss of central vision (blackout) to a white light with a luminance of 3.15 times 10-5 log candle/cm-2 (0.092 ft-lambert). The study began with a 14-d ambulatory control period, followed by three 14-d bedrest periods (each separated by a 21-d recovery period) and then a final week of recovery. During the ambulatory periods, the subjects exercised on a bicycle ergometer at 50% of their maximal oxygen uptake (max VO2) for 1 h/d. During two of the three bedrest periods, the subjects performed in the supine position one of two routines, either isometric exercise (21% of max leg extension force for 1 min followed by 1-min rest) or isotonic exercise (68% of max VO2) for 0.5 in the morning and afternoon. During the third bedrest period, no exercise was performed. In general +Gz tolerance was reduced by 24% to 35% (p less than or equal to 0.05) after bedrest. Compared with control values, there were significant reductions in average tolerance times after bedrest with no exercise and isotonic exercise at all G levels. With isometric exercise, there was a significant decrease in tolerance at 2.1 Gz but not at 3.2 Gz or 3.8 Gz, even though the latter tolerances were reduced 15.6% and 10.0%, respectively. Both exercise regimens maintained tolerance at levels equal to or above that obtained with no exercise. Compared with control values, average tolerances were lower (p less than or equal to 0.05) after the two recovery periods between the bedrest periods (minus 24% to minus 26% at 3.2 Gz and 3.8 Gz), indicating that 3 weeks of ambulation was not sufficient time for full recovery from the deconditioning induced in this study. A prediction equation was constructed with data from all comparable studies utilizing deconditioned men riding relaxed without protective garments: Tolerance (in seconds) equals minus 334 + (1715/+Gz level). From this equation, the calculated tolerance after bedrest is 13.5 min at 1.5 G, and the point of zero tolerance is 5.1 Gz.

Acceleration↗