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Biomedical subjects

R B Dilley

Publications and source records attributed to R B Dilley.

At least 55 records · Page 3Linked to original sources
PubMed1976

Prolonged pulseless perfusion in unanesthetized calves.

Nonpulsatile left ventricular (LV) bypass was achieved in nine alert, active calves for periods of up to two weeks using a centrifugal blood pump. Data were compared to prebypass control values and to results obtained from seven calves that underwent nonthoracotomy, retrograde LV cannulation, and pulsatile bypass for up to 35 days. Nonpulsatile flow produced an increase in heart rate of 20% (P less than .05) and an increase in aortic pressure of 10% (P less than .05). Cardiac output and systemic vascular resistance were similar in both groups for three days; thereafter, vascular resistance decreased as cardiac output progressively increased. Serum renin, lactate, and pyruvate values remained normal; creatinine clearances were not significantly different than control values, and there were no significant changes in body weight. These data indicate no untoward effects as a result of prolonged pulseless perfusion.

Anesthesia↗
PubMed1976

Aorto-left renal vein fistula: an unusual complication of abdominal aortic aneurysm.

A patient with an abdominal aortic aneurysm with a preaortic left renal vein fistula is presented. Review of the 7 reported cases of aorto-left renal vein fistulae demonstrates many similarities in the clinical presentation with aorto-caval fisulae. However, in addition to the triad of pain, pulsatile abdominal mass and bruit, commonly found in aorto-caval fistulae, the presence of hematuria, proteinuria, and azotemia suggests a renal vein fistula. Radiographic studies often demonstrate a large non-functional left kidney. Operative management of the fistula may be performed by a variety of maneuvers. All 7 patients survived. When repair was undertaken without delay, function in the left kidney returned to normal within two months postoperatively.

Acute Kidney Injury↗
PubMed1976

Adaptations of the left ventricle to chronic pressure overload.

Left ventricular (LV) function during the adaptation to chronic pressure overload produced by an ascending aortic constriction was analyzed in conscious dogs, instrumented with intraventricular micromanometers and pairs of ultrasonic crystals for measurement of LV wall thickness (WTh) and internal LV chamber diameter. During inflation of the cuff to produce LV pressures averaging 220 mg Hg, calculated peak wall stress (WSt) increased by 55% above control while percent shortening decreased by 24% and mean circumferential shortening velocity (VCF) decreased by 39% from control. By 9 days (mean) after aortic constriction, the cross-sectional area (CSA) of the LV wall increased by 10% and peak WSt fell to 37% above control. End-diastolic diameter (EDD) increased to 4% above control, while percent shortening and mean VCF remained reduced at -12% and -20% of control, respectively. During the phase of concentric hypertrophy (mean 2 1/2 weeks), CSA increased further to 15% above control and WSt fell to 22% above control, while EDD and percent shortening returned to control and mean VCF increased to -7% of control (not significant). At 24 hours after release of the cuff WSt, percent shortening, mean VCF, and peak velocity of LV pressure rise (peak dP/dt) were not significantly different from control. Rapid, partial regression of hypertrophy was observed in some dogs. Thus, the left ventricle responds to chronically elevated pressure by initial dilation with increased WSt followed by gradual wall thickening and consequent reduction of WSt to near normal. After successful adaptation to the pressure overload, hypertrophy per se did not produce intrinsic depression of the myocardial inotropic state.

Animals↗
PubMed1976

Growth rates of small abdominal aortic aneurysms.

A policy of utilizing B-mode ultrasound scan measurements of abdominal aortic aneurysms to help determine operability in poor-risk patients with small asymptomatic aneurysms has been pursued for the past 6 years. Indications for surgery in such patients have included enlargement to 6 cm. in any transverse diameter, the development of symptoms, or evidence of leak or rupture. In addition, patients treated nonoperatively have been followed by serial B-mode echo scans, permitting the accumulation of aneurysm growth rate data. Such data indicate that small aneurysms grow an average of 0.4 cm. per year, but that dramatic increases in aneurysm size may occur unexpectedly in asymptomatic patients. These data appear to have value in both individual decision making and as a baseline for weighting the various risk factors in the poor-risk patient with a small asymptomatic abdominal aortic aneurysm.

Aged↗
PubMed1976

The effects of pulseless perfusion on the distribution of renal cortical blood flow and on renin release.

The effects of pulseless perfusion on the distribution of renal blood flow and on release of renin were studied in anesthetized dogs. The distribution of renal blood flow to four cortical layers was determined with the radioactive microsphere technique during pulsatile control conditions and after one and 2 hours of pulseless perfusion, without significant changes in mean arterial pressure and mean total renal blood flow. Simultaneously, renal vein blood samples were analyzed for renin (radioimmunoassay technique). During pulseless perfusion there was a consistent and progressive redistribution of blood flow toward deeper cortical layers with the outer cortical layer falling from 36.9 to 25.3% p less than 0.001) and the juxtamedullary cortex increasing from 14.5 to 25.4% (p less than 0.001) after 2 hours. In addition, there was a progressive increase in renal venous concentration of renin, which was 20.91 +/- 6.6 ng. per millimeter per hour after 2 hours of pulseless flow compared to 5.06 +/- 1.16 ng. per millimeter per hour during control conditions (p less than 0.05). These changes in cortical blood flow and in release of renin were not observed in sham-operated controls. The results indicate that pulseless flow alone produced both a significant increase in renal production of renin and a significant redistribution of renal cortical blood flow, due to the greater vasoconstriction in the outer cortex when compared to the juxtamedullary cortex.

Animals↗