Assessment of the human coronary circulation using a Doppler catheter

Arteriographic estimates of stenosis severity can fail to reflect the impact of an individual stenosis on delivery of blood to the myocardium. Whether a coronary stenosis is truly flow-limiting can be determined by measuring hyperemic blood flow or coronary flow reserve; however, until recently, the tools needed to measure coronary flow reserve in humans--namely, a method of quantitating coronary blood flow in individual arteries and another method for producing maximal microvascular vasodilation--were not available. Over the last 8 years, our laboratory group has developed a catheter for measuring coronary blood flow velocity in humans, using the Doppler principle, and studied the effects of microvascular vasodilators. These studies have enabled us to measure coronary flow reserve in humans and to characterize some of the effects of focal and diffuse atherosclerosis on the coronary circulation. In addition, we have used flow reserve measurements in the diagnosis of microvascular dysfunction in patients with chest pain and normal coronary arteries and as a means of assessing noninvasive methods for detecting focal coronary artery disease.     

PLASMA VASOPRESSIN AND ATRIAL NATRIURETIC FACTOR DURING HAEMORRHAGE: INFLUENCE OF CARDIAC AND AORTIC RECEPTORS

1. The changes in plasma concentrations of immunoreactive vasopressin (iVP) and atrial natriuretic factor (iANF) in response to haemorrhage (10-30% blood volume) were measured in 10 anaesthetized rabbits before and after cardiac receptor denervation (vagal nerve section). Carotid sinus pressure was maintained constant (60 mmHg) to eliminate any changing input from carotid baroreceptors. 2. Haemorrhage increased iVP before and after vagal nerve section indicating that withdrawal of input from aortic baroreceptors may have contributed to the increase in iVP. 3. Section of the vagus nerves attenuated the iVP response to haemorrhage. 4. There was no correlation between release of iVP and iANF. 5. Haemorrhage decreased iAF before and after vagal nerve section. Section of the vagus nerves increased iANF. Plasma iANF was highly correlated with atrial pressure and mean arterial pressure suggesting iANF release was secondary to changes in cardiac haemodynamics.     

Staphylococcus epidermidis as a cause of postoperative wound infection after cardiac surgery: assessment of pathogenicity by a wound-scoring method

Wound infection after clean surgery prolongs hospital stay but the organism most commonly isolated from wound discharge, Staphylococcus epidermidis, is often dismissed as a contaminant or commensal. The wounds of 517 patients were assessed, after cardiac surgery, by a wound-scoring method ('ASEPSIS') and a close comparison was made of the appearance and clinical outcome of 89 wounds, from which bacteria were isolated. There was no significant difference in the scores of 49 wounds, where S. epidermidis was the sole isolate (9.5 per cent of all wounds, 95 per cent CI 6.9-12.0 per cent), and 13 wounds infected with Staphylococcus aureus (2.5 per cent, 95 per cent CI 1.2-3.9 per cent). Repeat cultures were obtained from 21 of the 49 wounds and, in 16 of these, the second isolate showed the same biochemical reactions and antibiotic resistance pattern as the first. Infection of sternal wounds is commoner with coagulase-negative staphylococci than with S. aureus and, clinically, is just as severe.     

Acute diverticulitis: safety and value of contrast studies in predicting need for operation

Results of treatment of 70 patients hospitalized with acute diverticulitis were analysed to determine the value of early contrast enema in management. A water-soluble enema done during the first week of hospitalization in 48 patients showed diverticulosis with spasm (30), a leak or peridiverticulitis (16) and a normal study (two). No complications were caused by the study. Forty patients improved on medical therapy, but four relapsed after discharge. Thirty-four (49%) patients had urgent operation during hospitalization for the acute episode of diverticulitis. Findings on contrast enema correlated with the need for surgery during the acute phase: 13 of 16 with peridiverticulitis or a leak compared with three of 30 with diverticulosis/spasm (P less than 0.001). Operations performed were: sigmoid resection and primary anastomosis (17) with covering colostomy (five). Hartmann's operation (eight), colostomy and/or drainage (seven), right hemicolectomy (two). Findings at surgery were: abscess (15), phlegmon (12), peritonitis (five) and colovesical fistula (two). It is concluded that early contrast enemas of the distal colon done with appropriate precautions are useful in confirming the diagnosis of diverticular disease: only two of 48 studies were falsely negative. A pericolic extravasation (as opposed to a small sinus tract) or abscess usually indicates need for operation, whereas the finding of diverticulosis/spasm suggests a favourable outcome of conservative management.