Biomedical subjects

L A Brunsting

Publications and source records attributed to L A Brunsting.

30 records · Page 2Linked to original sources

PubMed1988

Traumatic fracture of the abdominal aorta. Rupture of a calcified abdominal aorta with minimal trauma.

We report the case of an elderly man whose infrarenal abdominal aorta ruptured when the patient fell getting out of bed. Unique features of this case are the lack of aneurysmal disease, the insignificant nature of the trauma, and the severe, rigid atherosclerotic plaque in the infrarenal aorta. Pathologic examination of the resected aorta demonstrated the point of rupture to be at the junction of atherosclerotic plaque and normal aorta, suggesting that atherosclerosis is a predisposing factor in traumatic rupture of the abdominal aorta.

Abdominal Injuries↗

PubMed1987

Preload dependence of right ventricular blood flow: I. The normal right ventricle.

Right ventricular (RV) failure is commonly treated with intravascular volume expansion to increase the RV-left atrial pressure gradient and improve left-sided filling. As RV pressure rises, chamber distention occurs and wall tension increases. These studies were designed to determine if increased wall tension might impede RV myocardial blood flow in the normal canine right ventricle and thus contribute to RV failure. Hemodynamic data, the septal-RV free wall dimension, and RV myocardial blood flow were obtained at low and high levels of preload and in both the autoregulated and vasodilated (adenosine, 2 mg per kilogram of body weight per minute) states. Elevated filling pressure decreased RV myocardial blood flow in both the autoregulated (0.85 +/- 0.18 to 0.67 +/- 0.15 ml/min/gm; p less than .05) and vasodilated (2.25 +/- 0.50 to 0.85 +/- 0.25 ml/min/gm; p less than .05) states but did not change the transmural distribution of blood flow to the right ventricle. Vasodilator reserve was markedly impaired in the high-preload state. These observations suggest that preload is an important determinant of RV myocardial blood flow. Volume loading to treat RV dysfunction may be limited by impairment of RV myocardial blood flow.

Animals↗

PubMed1987

Gastric rupture from blunt abdominal trauma.

Gastric rupture from blunt abdominal trauma is a rare occurrence. Six patients are presented and reviewed with the literature since 1930. Several features of the diagnosis and management of this injury are emphasized, including a strong association with thoracic trauma and a high incidence of intra-abdominal abscess formation which results from massive intraperitoneal contamination. Mortality is not usually from gastric rupture per se, but rather from concomitant vascular or neurologic injury. The key to survival for these patients is early operative intervention and an aggressive approach to reoperation and drainage of abscesses.

Abdomen, Acute↗

PubMed1987

Myocardial protective effects of the class Ic antiarrhythmic agent flecainide.

The class Ic antiarrhythmic agent flecainide has recently become available in this country for management of ventricular arrhythmias. The pharmacologic and electrophysiologic features of this class of drug--marked sodium channel blockade producing inhibition of phase 0 of the myocardial action potential, moderate blockade of slow inward (calcium) channels, and general lack of systemic toxicity--suggest that these agents may exert significant myocardial protective effects. This hypothesis was tested in isolated, perfused rat hearts subjected to 30 minutes of global normothermic ischemia followed by 30 minutes of reperfusion after pretreatment with (1) Krebs-Henseleit buffer (n = 7); (2) Krebs-Henseleit buffer with potassium adjusted to 20.9 mmol/L with potassium chloride (n = 10); and (3) Krebs-Henseleit buffer plus flecainide acetate 50 mg/L (0.12 mmol/L) (n = 11). Severity of ischemic injury was assessed by time to ischemic contracture: 9.9 +/- 1.3 (Krebs-Henseleit buffer), 18.4 +/- 1.1 (potassium chloride), and 25.4 +/- 1.0 (flecainide) minutes (mean +/- standard error of the mean) (p less than 0.05 among all groups). Functional recovery after ischemia and reperfusion was measured by developed pressure (expressed as percent of preischemic control): 19.6 +/- 5.4 (Krebs-Henseleit buffer), 70.8 +/- 3.2 (potassium chloride), and 67.3 +/- 2.7 (flecainide). These results suggest that class Ic agents afford significant myocardial protection from global normothermic ischemia.

Animals↗

PubMed1987

Ventricular function after atrial cardioplegia.

Continuous retrograde coronary sinus cardioplegia (CSCP) has previously been carefully evaluated experimentally and shown to be efficacious during ischemia, even in the presence of coronary lesions and in the hypertrophied state. A new technique of retrograde cardioplegia delivery through the right atrium, using right ventricular distension and pressures of 60 mm Hg, has recently been described with excellent clinical results. This study was designed to specifically examine right ventricular function after atrial cardioplegia and acute passive right ventricular distension. CSCP (n = 10) was compared with cardioplegia delivered through the right atrium both continuously (n = 10) and intermittently (n = 8). When ventricular function was examined with the use of the load-independent relationship of stroke work vs end-diastolic length, there was a profound deterioration of right ventricular function in both atrial cardioplegia groups (44% and 37% of control values, respectively) after 1 hr of reperfusion. In contrast, biventricular function was fully preserved in the CSCP group 1 hr after reperfusion. Left ventricular function measured at the end of reperfusion was preserved in all three groups. Right ventricular ATP levels were slightly but significantly depressed in all groups and in the atrial cardioplegia groups, this metabolic change was also seen in the left ventricle. These metabolic and hemodynamic data may reflect the inability of atrial cardioplegia to cool the myocardium below 16 degrees C. Postoperative right ventricular dysfunction may be more common than has been previously thought when atrial cardioplegia is used, particularly in the absence of topical cooling.

Adenine Nucleotides↗

PubMed1986

Myocardial protection.

Early studies of myocardial protection were designed to minimize ischemic injury. The next class and generation of investigations will most likely be designed to accelerate recovery following known myocardial injury. Such techniques will play an important role in allowing operations on acutely injured and ischemic myocardium and will be important in the treatment of postischemic injury when such injury occurs during the course of complex cardiac operations. Surgical aspects of myocardial metabolism are still rudimentary and many empiric observations require further exploration into the mechanisms by which such applications work.

Adenosine Monophosphate↗

PubMed1986

Reproductive hormone increases in response to acute exercise in men.

The increase in serum testosterone levels generally observed with intense, short-term exercise remains unexplained since most investigators have not reported any increase in the levels of luteinizing hormone, the pituitary glycoprotein most responsible for testicular steroidogenesis. Hemoconcentration and decreased metabolic clearance have been suggested as mechanisms to explain the exercise-associated testosterone increase. Such non-specific mechanisms should apply to other steroid hormones as well as to testosterone. To investigate whether the exercise-induced changes in other steroid hormones were similar to that of testosterone, we measured serum levels of testosterone, androstenedione, dehydroepiandrosterone, and cortisol as well as gonadotropins, luteinizing hormone and follicle-stimulating hormone, and prolactin at 5-15 min intervals throughout progressive maximal intensity exercise on a cycle ergometer. Significant increases were observed with all hormones with exercise. The increase in serum testosterone began prior to exercise, peaked at 20 min after the beginning of exercise, and fell to baseline within 10 min. The serum luteinizing hormone increase was synchronous with that of testosterone, suggesting that gonadotropin stimulation was not responsible for the testosterone increment. The increments in serum cortisol, androstenedione, dehydroepiandrosterone, and prolactin levels were simultaneous but began 25-30 min after that of testosterone in all subjects. These findings, therefore, suggest that, contrary to previous evidence, the exercise-associated increase in serum testosterone results predominantly from a specific mechanism, presumably involving increased testicular production without gonadotropin stimulation.

Adult↗

PubMed1986

Papillary-annular continuity and left ventricular systolic function after mitral valve replacement.

The contribution of the subvalvular apparatus to left ventricular function was evaluated in a canine preparation that allowed variation of subvalvular tethering forces after mitral valve replacement. Ten normal dogs were instrumented with micromanometer-tipped pressure catheters in the left ventricle and left atrium and piezoelectric sonomicrometry crystals to measure left ventricular major-axis, minor-axis, and wall thickness dimension changes. After control data were obtained, each dog underwent cardiopulmonary bypass and the mitral valve was replaced with a St. Jude bileaflet valve (No. 23 or 25). The native valve was completely excised and all chordal attachments were severed at the head of each papillary muscle. A 3-0 prolene suture was passed through the head of each papillary muscle, gently tied over a pair of felt pledgets, and exteriorized in a paravalvular manner that allowed both "attached" and "detached" states to be studied in a randomized manner 1 hr after release of the aortic cross-clamp. A significant (p less than .05) increase in major-axis length from control was observed in the detached state at both end-diastole and end-systole when compared at matched left ventricular end-diastolic pressures. Systolic function measured by load-dependent variables at matched end-diastolic lengths was higher in the detached state. However, when systolic function was examined by load-independent variables such as the slope of the stroke work end-diastolic length relationship, the slope of the end-systolic pressure-volume relationship, or the stroke work end-diastolic volume relationship, no statistically significant difference could be detected between states of papillary-annular continuity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1929