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Biomedical subjects

R R Nelson

Publications and source records attributed to R R Nelson.

29 records · Page 2Linked to original sources
PubMed1978

The rate-pressure product as an index of myocardial oxygen consumption during exercise in patients with angina pectoris.

In order to evaluate hemodynamic predictors of myocardial oxygen consumption (MVO2), 27 normotensive men with angina pectoris were studied at rest and during a steady state at sympton-tolerated maximal exercise (STME). Myocardial blood flow (MBF) was measured by the nitrous oxide method using gas chromatography. MBF increased by 71% from a resting value of 57.4 +/- 10.2 to 98.3 +/- 15.6 ml/100 g LV/min (P less than 0.001) during STME while MVO2 increased by 81% from a resting value of 6.7 +/- 1.3 to 12.1 +/- 2.8 ml O2/100 g LV/min (P less than 0.001). MVO2 correlated well with heart rate (HR) (r = 0.79), with HR x blood pressure (BP) (r = 0.83), and, adding end-diastolic pressure and peak LV dp/dt as independent variables, slightly improved this correlation (r = .86). Including the ejection period (tension-time index) did not improve the correlation (r = 0.80). Thus, HR and HR x BP, both easily measured hemodynamic variables, are good predictors of MVO2 during exercise in normotensive patients with ischemic heart disease. Including variables reflecting the contractile state of the heart and ventricular volume may further improve the predictability.

Adult↗
PubMed1977

Exercising pulmonary blood flow in mitral stenosis with anomalous pulmonary venous connection.

Exercising pulmonary blood flow was estimated from indicator-dilution curves in a patient with the infrequent combination of rheumatic mitral stenosis and anomalous pulmonary venous connection from the left lung. During supine exercise against progressively increasing external workloads, the proportion of flow to each lung remained nearly constant. The pulmonary vascular resistance was highest in the left lung, which emptied into the low-pressure systemic vein. Although right and left atrial pressures differed markedly during supine exercise, the proportion of pulmonary blood flow shunted to the systemic venous sytem remained essentially unchanged.

Adult↗
PubMed1976

Ventricular dimensions measured noninvasively by echocardiography in the awake dog.

A surface echocardiographic technique was employed in 37 mongrel dogs for measurement of left ventricular dimensions. Intracardiac bolus injections of dextran were used as an echo contrast material to visualize cardiac chambers, and the identification of intracardiac structures was further confirmed by postmortem examination. The left ventricle could be satisfactorily visualized from both the right and left chest, providing two transverse left ventricular diameters nearly perpendicular to each other. End-diastolic and end-systolic diameter measurements in the two separate transverse planes differed by an average of only 0.07 and 0.1 cm, respectively, and dimensional measurements were reproducible from day to day. Diastolic diameter ranged from 3.0 to 4.7 cm (mean 3.7 cm) and systolic diameter 1.9 to 3.3 cm (mean 2.6 cm). Diameter was directly related to animal weight. Stroke volume calculated from the dimension measurements correlated with stroke volume calculated from indicator-dilution curves in 16 dogs. Ejection fraction averaged 0.67 and 0.54, depending on the formula used to calculate volumes. These results indicate that surface echocardiography can be employed to evaluate left ventricular dimensions in the awake dog.

Animals↗
PubMed1968

Murine Toxicity of Cochliobolus carbonum.

Seventeen wild-type strains of the phytopathogenic fungus Cochliobolus carbonum, tested by intraperitoneal injection into mice, were lethal within 48 hr. The lethal effect appeared to be a toxic rather than an infectious process, because death occurred within 3 hr after injection of two of the isolates and heat-killed cultures were lethal. Assays of ascospore progeny from two crosses involving three isolates indicated that the toxic metabolites were under genetic control and quantitative regulation. Studies of the toxicological, cultural, and chemical characteristics of these three strains indicated that more than one murine toxin was present.

Journal Article↗
PubMedDate not supplied

Exclusion of atrial thrombus by transesophageal echocardiography.

To determine whether transesophageal echocardiography (TEE) is useful in ruling out the presence of atrial thrombus, we performed TEE in 20 patients immediately before valve replacement or valve repair and within 3 days of an autopsy in one patient. Mitral stenosis was the predominant lesion in three patients, mitral regurgitation was seen in 11 patients, five patients had mitral prosthesis malfunction, one patient had a tricuspid prosthesis malfunction, and one patient had aortic stenosis. Eight patients were in atrial fibrillation. Four patients demonstrated spontaneous contrast in the associated atria. Nine patients were receiving oral anticoagulation. Mean left atrial diameter was 5.3 +/- 1.3 mm. TEE revealed no evidence for atrial thrombus in 18 of the 21 patients; this finding was confirmed by careful inspection of the atria including the appendages. TEE demonstrated a left atrial thrombus in two patients and a right atrial thrombus in another (confirmed at the time of surgery or at autopsy). In all cases transthoracic echocardiography was negative. Our data suggest that TEE is useful in ruling out atrial thrombus, and therefore may be a useful test preceding interventions associated with an increased risk of embolism from the atria such as cardioversion, mitral valvuloplasty, or valve replacement.

Adult↗
PubMedDate not supplied

Wound healing and repair: a review of the art and science.

This chronological review of the major biological events that occur secondary to injury of mucoperiosteal tissue from either simple surgical wounding or trauma discusses the materials used to repair the compromised tissue surgically. Suturing techniques and post-surgical wound maintenance also are reviewed. The physiological stages of wound healing, factors affecting wound healing, and wound repair techniques are discussed.

Connective Tissue↗