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Biomedical subjects

R J Gray

Publications and source records attributed to R J Gray.

At least 145 records · Page 8Linked to original sources
PubMed1982

Myocardial metabolism and hemodynamic responses to halothane or morphine anesthesia for coronary artery surgery.

Eighteen patients having coronary artery bypass grafts were randomly anesthetized with morphine (1 mg/kg) or halothane and oxygen. Central and peripheral pressures were measured serially, plus cardiac output and total coronary sinus blood flow, both by thermodilution catheters, starting before induction of anesthesia and continuing until completion of sternotomy. No significant differences in hemodynamic responses were seen between the two anesthetic techniques during induction: blood pressure and peripheral vascular resistance decreased significantly, but not cardiac output or coronary flow. Myocardial oxygen consumption decreased significantly with induction as oxygen content of coronary sinus blood increased, indicating preservation of oxygen balance. Heart rate and blood pressure increased after sternotomy in the patients given morphine, with the myocardium producing lactate in two of six patients and with nitroprusside being required in four patients to decrease arterial pressure. Halothane-oxygen anesthesia effectively controlled autonomic responses to sternotomy, although one of 12 patients had myocardial lactate production at that time. Neither rate-pressure product or ST segment changes were useful predictors of the ratio between myocardial oxygen consumption and supply. Myocardial oxygen balance can be maintained in coronary patients before cardiopulmonary bypass if pulse rate and blood pressure are kept at less than awake levels.

Adult↗
PubMed1982

Dobutamine and cardiac oxygen balance in patients following myocardial revascularization.

Dobutamine is frequently used in the early postoperative period following myocardial revascularization to improve cardiac output. Seven postoperative adult patients with low output syndrome were studied before and during intravenous dobutamine (mean +/- SD: 5.1 +/- 2.5 micrograms/kg/min) infusion. The metabolic effects were evaluated and related to hemodynamic changes. Cardiac index increased 40% (p less than 0.05) with an increase in heart rate (p less than 0.05) and decreases in systemic vascular resistance and right atrial pressure (p less than 0.05). No significant changes occurred in arterial or pulmonary capillary wedge pressures or in stroke volume index. Dobutamine produced a 29% increased in myocardial oxygen consumption which, in these revascularized patients, was accompanied by a 35% increase in coronary blood flow. No significant alteration was observed in coronary sinus oxygen content or in global myocardial lactate extraction. Thus, despite the increased metabolic cost of dobutamine, global myocardial ischemia was not observed.

Blood Pressure↗
PubMed1982

Cardiovascular effects of morphine in patients with coronary arterial disease.

Large doses of morphine sulfate have been reported to cause myocardial lactate production and reduction in coronary blood flow in animals. Similar effects with clinical doses in man would significantly alter the management of cardiac patients. Eleven adult patients with significant coronary arterial disease and normal left ventricular ejection fraction were studied before and 30 minutes after infusion of morphine (0.25 mg/kg IV). Evaluation of myocardial metabolism showed an increase in coronary sinus oxygen content (p less than 0.001) and a reduction in myocardial oxygen consumption. Myocardial lactate extraction was not altered. No change in coronary sinus blood flow was seen. It is concluded that infusion of morphine sulfate, 0.25 mg/kg IV, does not produce global myocardial ischemia in patients with coronary artery disease and normal ventricular function.

Aged↗
PubMed1982

Effects of protamine sulfate on myocardial oxygen supply and demand in patients following cardiopulmonary bypass.

The effect of protamine sulfate on myocardial oxygen supply and demand was studied under clinical conditions in nine patients following cardiopulmonary bypass. Before surgery, the patients had severe coronary artery disease with good ventricular function. The patients required no vasoactive drugs, but only blood volume adjustments when weaned off bypass, and were hemodynamically stable at the time of study. The protamine dose of 196 mg (2.5 mg/kg) was infused over 4 +/- 1 minutes. Although modest variation in hemodynamic function occurred in individual patients after administration of protamine, there were no significant hemodynamic alterations for the group. No significant alteration in global myocardial metabolism was observed. Protamine caused a small decrease in measured coronary blood flow, resulting in a corresponding reduction in calculated myocardial oxygen consumption as coronary sinus oxygen content remained unaltered. Myocardial lactate extraction showed no significant alteration. It is concluded that protamine sulfate, given at rapid infusion rates in hemodynamically stable patients, is not associated with an adverse alteration in hemodynamics or global myocardial metabolism.

Aged↗
PubMed1981

Improvement in global and segmental left ventricular function after coronary bypass surgery.

Ventricular function was assessed at rest and during exercise by multiple gated cardiac blood pool scintigraphy before and after coronary artery bypass surgery in 21 patients. Resting left and right ventricular ejection fraction and segmental wall motion were unchanged by surgery. However, the postoperative exercise response of left ventricular ejection fraction (-1 +/- 12% vs 6 +/- 9%) and segmental wall motion score (medium -2.7 [range -8 to 2] vs -0.4 [range -6 to 2]) were significantly improved (p less than 0.05). The normal right ventricular ejection fraction exercise response was maintained after surgery. Previous myocardial infarction in 15 patients did not attenuate the observed improvement in ventricular function. In addition, normal postoperative left ventricular ejection fraction response to exercise was associated with symptomatic improvement. In three of six patients a normal preoperative left ventricular ejection fraction response to exercise was not maintained. Therefore, global and regional left ventricular reserve is improved by coronary bypass surgery and this improvement is not affected by previous myocardial infarction.

Adult↗
PubMed1981

An appreciation of the new St. Jude valvular prosthesis.

Beginning in March, 1978, 88 patients have had cardiac valve replacements with St. Jude prostheses. There were 26 males and 62 females, aged 6 to 80 years (mean 60). Single valve replacement was done in 67. Double valve replacement was done in 21; 12 of them had two St. Jude valves and nine had a different second valve. There were 57 mitral and 43 aortic valves replaced. Thirty-six patients had concomitant aorta-coronary bypass, and six others had additional cardiac procedures. All patients have been followed for a total of 807 patient-months (mean 9 months). Seventy-nine have been receiving sodium warfarin and seven are not receiving anticoagulants. There has been one embolic episode. There are no valve failures to date. Early mortality is 2.3% and late mortality, 5.7%; no death was valve related. Fifty-three survivors have improved by two or more N.Y.H.A. classifications. Fifty-four valves studied postoperatively at rest, during pacing, and during isoproterenol infusion have demonstrated significantly better hemodynamic performance than have mitral porcine xenografts studied in an identical manner (p < 0.05). Phonocardiography, M-mode and two-dimensional echocardiography, and cinefluoroscopy, carried out in 18 patients, have proved to be reliable noninvasive techniques for long-term follow-up. This experience indicates that the St. Jude prosthesis offers an excellent and predictable alternative in the surgeon's decision-making concerning valve choices.

Adolescent↗
PubMed1978

Quantification of myocardial injury during coronary artery bypass graft.

Serial intraoperative myocardial-specific creatine-kinase (MB-CK) samples were obtained in 32 patients undergoing coronary artery bypass graft (CABG). Based upon their postoperative ECG and technetium pyrophosphate SCAN results, each patient was classified as either Group A (MI), B (normal), or C (equivocal). Peak MB-CK was reported for each group. The mean value for Group A (75 +/- 17 IU/L) is higher than for Group B (18 +/- 1 IU/L) or Group C (30 +/- IU/L). The concept of measuring and a formula for calculation of intraoperative myocardial injury are presented. The mean value for Group A (MI, 10,709 +/- 5885) is higher than either groups B (normal) or C (equivocal) by a test of proportionality (P < 0.001). Likewise, Group C (898 +/- 159) is higher than B (466 +/- 71) (P < 0.05). This index, while in need of further validation, corresponds closely to the clinical status of the 32 patients studied and should provide a means more refined than mortality or incidence of MI upon which to judge efficacy of any proposed means of operative myocardial preservation.

Aged↗
PubMed1978

Aneurysm of the cardiac ventricle. Its management by medical and surgical intervention.

Ventricular aneurysm is usually a complication of acute transmural myocardial infarction. The development of cardiac aneurysm represents a process of continued thinning and fibrosis of the necrotic tissue of the ventricular wall. Survival allows the development of a solid fibrous scar which of itself does not affect global ventricular function substantially. Hence, ventricular aneurysms can be present for up to 18 years without production of serious symptoms. The cases were reviewed of 45 patients in whom aneurysmectomy and myocardial revascularization were carried out. Surgical mortality was low (6.6 percent, 30 days); survival one year after operation was 76 percent, but at three years had fallen to 47 percent. Cause of late death was dominantly cardiac. In 19 patients post-operative study was done; although graft patency was observed in 98 percent, substantive improvement in ventricular performance was seen in a minority of patients. The outcome in patients with ventricular aneurysm is primarily related to the status of the residual myocardium and to the status of the vessels which supply it. The mechanism of clinical improvement after aneurysmectomy has not been clarified. However, the long-term results appear to be similar to those in patients with extensive myocardial infarction.

Adolescent↗
PubMed1977

Diluent sensitivity in thermally stressed cells of pseudomonas fluorescens.

Thermally injured cells of Pseudomonas fluorescens were unable to produce colonies on Trypticase soy agar (TSA) after dilution with 0.1% peptone. Nutritional exigency could not be used as the criterion for this injury, since varying the composition of the plating medium had little effect on the number of colonies that developed. The injured cells had no requirement for compounds known to leak out during the heat treatment in order to recover. The cells did not exhibit injury if dilution preceded heat treatment on the plating medium, demonstrating that the heat treatment sensitized the cells to the trauma of dilution. Substitution of 0.1% peptone with growth medium as the diluent largely offset the previously observed drop in TSA count. Little difference in survival was observed when monosodium glutamate or the balance of the defined medium was used as the diluent. The diluent effect was ionic rather than osmotic. The presence of cations was important in maintaining the integrity of the injured cell, and divalent cations enhanced this protective effect. The role of these cations at the level of the cell envelope is discussed.

Cations, Divalent↗
PubMed1977

Function of cell wall teichoic acid in thermally injured Staphylococcus aureus.

Thermally injured cells of Staphylococcus aureus lack the ability to grow on tryptic soy agar containing 7.5% NaCl. This injury phenomenon was examined in three strains of S. aureus: MF-31; H (Str); and, isolated from H (Str), 52A5, a mutant which lacks teichoic acid in the cell wall. Temperatures for sublethal heat treatment were selected to produce maximum injury with minimum death for each strain. Examination of isolated cell walls showed that magnesium was lost from the wall during heating, and that the degree of cell injury was accentuated when magnesium ions were either removed from or made unavailable to the cell. S. aureus 52A5 was more heat sensitive than its parent strain. Cells containing higher levels of wall teichoic acid generally showed less injury than normal cells. Cells with the weaker cation-binding polymer, teichuronic acid, in the cell wall generally showed greater injury. These data suggest that cell wall teichoic acid of S. aureus aids in the survival of the cell by the maintenance of an accessible surface pool of magnesium.

Calcium Chloride↗
PubMed1977

Coronary sinus blood flow and sampling for detection of unrecognized myocardial ischemia and injury.

Fifteen patients were studied to detect unrecognized intraoperative ischemia or necrosis in perioperative myocardial infarction (MI) associated with coronary bypass. Simultaneous arterial and coronary sinus blood samples were analyzed for lactate and both total and MB-CPK. Coronary sinus flow measurements were done coincident with sampling in seven patients. Five had perioperative MI diagnosed by positive pyrophosphate scan and electrocardiogram. Although normal initially (mean 19 +/- 5.0%), lactate extraction after thoracotomy, before aortic cross-clamping, became abnormal in 12 patients with more pronounced abnormality in those with perioperative MI (-19 +/- 9.0%). Net efflux of lactate was higher in perioperative MI (mean 0.6 +/- 0.2 vs 0.016 +/- 0.04 mM/L) than in non-MI patients. All patients had detectable total and MB-CPK (mean 295 and 31 IU/L, respectively) and all those with coronary disease had a positive arterial-coronary sinus gradient for MB-CPK (mean 9 IU/L). Perioperative MI patients had a higher gradient than non-MI patients (mean 25 vs 2 IU/L) and with one exception that gradient exceeded 5-7 IU/L. It is concluded that severe ischemia before aortic cross-clamping precedes perioperative MI and may contribute to release of CPK into coronary sinus blood. Improvement in the techniques of anesthesia and intraoperative myocardial preservation are suggested.

Adult↗
PubMed1973

Characterization of mild thermal stress in Pseudomonas fluorescens and its repair.

The exposure of exponentially growing Pseudomonas fluorescens P7 cells to heating at 36 C for 2 h in a defined medium, followed by cooling to 25 C and further incubation at this, the optimal growth temperature, resulted in the apparent death of approximately 99% of the cells, as determined by their inability to form colonies on Trypticase soy agar. Continued incubation at 25 C resulted in an extremely rapid increase in the Trypticase soy agar count, demonstrating that the phenomenon observed was not death but rather injury. Presumptive evidence of heat-stimulated ribonucleic acid (RNA) degradation and membrane damage was provided by the observed loss of 260-nm absorbing materials. Confirmation of RNA degradation was obtained by colorimetric analysis. Ribosomal RNA from normal and injured cells, which was electrophoretically separated on polyacrylamide gels, revealed that the 23S and 16S species were only partially destroyed. Inhibitor studies demonstrated, however, that RNA synthesis was necessary for recovery. The unusual accumulation of 17S RNA during recovery pointed to the presence of a heat-induced lesion in the RNA maturation process. A thermally induced membrane lesion is also discussed.

Agar↗
PubMed1967

Poloxalene as an anti-bloat compound and its effect on milk yield and composition.

Poloxalene, a nonionic surfactant, was fed to beef cattle on a legume ration or a high grain ration to observe its effect on bloat. It was also fed to lactating dairy cows to note any effect on yield or composition of milk. Poloxalene was beneficial in the prevention of bloat with both legume and grain rations. It had no effect on per cent fat, protein, solids-not-fat, or yield of milk.

Animals↗
PubMedDate not supplied

Percutaneous hepatic venous reanastomosis in a patient with Budd-Chiari syndrome.

A 33-year-old woman with Budd-Chiari syndrome for 9 years presented with worsening right upper quadrant pain and progressive liver dysfunction. Hepatic venography demonstrated hepatic vein occlusions, without significant IVC obstruction. Attempts at stenting a stenotic middle hepatic vein were unsuccessful. Transjugular access, however, allowed puncture from the stump of the right hepatic vein into the engorged right intrahepatic vein that had been demonstrated by retrograde hepatic venography. Two Palmaz stents were used to form the veno-venous reanastomosis. Initial success was documented angiographically and by pressure measurements before and after shunting. Followup at 7 and 16 months confirmed patency of the anastomosis without intimal hyperplasia. The patient noted near-complete resolution of her pain, and her liver function stabilized.

Adult↗