Regulation of atrial natriuretic peptide release in normal humans

Atrial volume, pressure, and heart rate are considered the most important modulators of atrial natriuretic peptide (ANP) release, although their relative role is unknown. Continuous positive-pressure breathing in normal humans may cause atrial pressure and atrial volume to go in opposite directions (increase and decrease, respectively). We utilized this maneuver to differentially manipulate atrial volume and atrial pressure and evaluate the effect on ANP release. Effective filling pressure (atrial pressure minus pericardial pressure) was also monitored, because this variable has been proposed as another modulator of ANP secretion. We measured right atrial (RA) pressure, RA area, esophageal pressure (reflection of pericardial pressure), and RA and peripheral venous ANP in seven healthy adult males at rest and during continuous positive-pressure breathing (19 mmHg for 15 min). Continuous positive-pressure breathing decreased RA area (mean +/- SE, *P less than 0.05) 13.6 +/- 1.1 to 10.5 +/- 0.8* cm2, increased RA pressure 4 +/- 1 to 16 +/- 1* mmHg, increased esophageal pressure 2 +/- 1 to 12 +/- 1* mmHg, and increased effective filling pressure 2 +/- 0 to 4 +/- 1* mmHg. RA ANP increased from 67 +/- 17 to 91 +/- 18* pmol/l and peripheral venous ANP from 43 +/- 4 to 58 +/- 6* pmol/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial natriuretic peptide, renin and aldosterone in obstructive lung disease and heart failure

Elevations of atrial natriuretic peptide (ANP) in congestive heart failure (CHF) and chronic obstructive lung disease (COLD) are presumably due to atrial hypertension, while secondary hyperaldosteronism in these patients is thought to result from diminished renal perfusion. The responsiveness of the ANP and renin (PRA)-aldosterone (PA) systems to acute increases in right atrial pressure has not been studied in these patients, but in normals a reciprocal relationship between ANP with PRA and PA has been shown. The authors monitored venous pressure (VP, reflective of right atrial pressure), ANP, PRA and PA in 15 stable COLD patients, seven stable CHF patients and three normal controls at baseline and after elevation of VP by antishock trousers. Inflation of the trousers resulted in increased VP and ANP (p less than 0.05): control ANP, 84 +/- 17 to 108 +/- 23 pg/ml; COLD ANP, 176 +/- 5 to 200 +/- 7; and CHF ANP, 388 +/- 20 to 499 +/- 37. PRA and PA were not suppressed by increasing ANP levels and the delta ANP/delta VP ratio was similar among groups. No intergroup differences in resting PRA and PA were noted, but PRA was higher (p = 0.007) and PA tended to be higher (p = 0.08) in a sub-group of six edematous patients, as compared with non-edematous patients and controls. These findings: (1) confirm previously reported ANP differences between COLD and CHF; (2) indicate that the ANP system remains responsive to physiologic manipulations in COLD and CHF; and (3) demonstrate that ANP and the PRA-PA axis are not reciprocally related in either group.

Enteroclysis in the evaluation of suspected small intestinal bleeding

One hundred twenty-five consecutive enteroclysis studies performed for the indication of gastrointestinal bleeding were reviewed. The overall yield of positive studies was low (10%) but important lesions were found. Patients with unequivocally normal evaluations of the upper gastrointestinal tract and colon had the highest yield of positive enteroclysis studies (20%). Neither the specific type of bleeding, the presence or absence of abdominal symptoms or physical examination findings, nor the results of laboratory tests were associated with a positive or negative enteroclysis study.

Diverticular disease: imaging with post-double-contrast sigmoid flush

In a prospective study, the effect of infusion of a low-density contrast material was evaluated as an adjunct to high-density, double-contrast imaging of the sigmoid colon. After double-contrast barium enema (DCBE) study, 52 consecutive patients with sigmoid diverticulosis received an additional 500-750-mL enema either with water or a 1.5% barium suspension for computed tomography. Rectosigmoid radiographs were evaluated for luminal distention, visualization of the interhaustral space, definition of diverticula, and interpretation of polypoid defects. While double-contrast views were excellent in 21% of patients, improvement in multiple factors by water or 1.5% barium flush resulted in improved sigmoid images in 65% and 75% of patients, respectively. Polyps were confirmed and artifactual defects confidently excluded. Sigmoid flush, particularly with low-density barium, is a simple adjunct to DCBE study that improves visualization of the diverticular sigmoid and increases interpretive confidence.

Percutaneous transluminal angioplasty and valvectomy in a failing in situ saphenous graft

A patient is described who experienced increasing ischemia in the follow-up period of femoral-peroneal artery graft surgery. Transcatheter angiographic management was successful in improving the long-term patency of the graft. The procedure is described, and the applications are discussed.

Focal fatty infiltration of the liver: diagnostic imaging

The authors here describe a number of imaging features which together are distinctive and may be diagnostic of focal fatty infiltration of the liver.

Bacteremia during double-contrast barium enema examination

Forty-five patients undergoing double-contrast barium enema examinations were studied to identify the incidence of transient bacteremia associated with the examination. Blood cultures were obtained immediately prior to the examination and at 5, 10, and 20 minutes after the start of the examination. Blood samples were cultured in both aerobic and anaerobic media, and four of these cultures were positive for organisms that are common skin contaminants. No bacteremia was identified from enteric pathogens. The data herein suggest that patients with cardiac valvular disease are not at greater risk of bacteremia during double-contrast barium enema examinations.

Roentgenographic manifestations of maxillomandibular renal osteodystrophy

We examined 30 male chronic hemodialysis patients and 18 male controls without known bone or renal disease to determine the utility of maxillomandibular, non-dominant hand, shoulder and pelvis films in the evaluation of renal osteodystrophy. We used panoramic periapical radiographs to examine the maxilla and mandible and sensitive rapid processing films for the hand, shoulder and pelvis. Films were evaluated by experienced personnel without knowledge of the patients. There were significant differences between patients and controls in creatinine, urea nitrogen, total protein, albumin, alkaline phosphatase and phosphorus. Twenty-three patients had abnormal hand radiographs and 22 patients had abnormal jaw radiographs (p less than 0.05 vs. controls). Four patients had changes in the hands, but not in the jaw; 4 had opposite findings. Changes in the jaw tended to be more severe than in the hands in those with involvement of both. We concluded that dental and hand radiography are good screening techniques for evaluating bone disease. They may be useful in evaluating treatment for renal osteodystrophy.

A blinded prospective study comparing four current noninvasive approaches in the differential diagnosis of medical versus surgical jaundice

A prospective study was undertaken to compare the diagnostic accuracy of clinical evaluation, ultrasound, computed tomography, and technetium 99m-HIDA or -PIPIDA biliary scans in distinguishing between intrahepatic and extrahepatic jaundice. A final diagnosis was established in each of the 50 patients who completed the study, among whom 29 had intrahepatic cholestasis and 21 had extrahepatic obstruction. In the diagnosis of extrahepatic obstruction, the sensitivities of clinical evaluation, ultrasound, computed tomography, and nuclear medicine biliary scan were 95%, 55%, 63%, and 41%, respectively; the specificities were 76%, 93%, 93%, and 88%; and the overall accuracies were 84%, 78%, 81%, and 68%. These data support the conclusion that when the clinical evaluation is carefully performed, it is the single most effective noninvasive means of detecting extrahepatic biliary obstruction in a jaundiced patient. Although ultrasound, computed tomography, and radionuclide biliary scan are less sensitive, they are highly reliable if they indicate that extrahepatic obstruction is present. A flow chart of invasive and noninvasive approaches for evaluation of the jaundiced patient is presented.

Plasma aminoacid levels across the brain in patients with respiratory failure

Animal studies and theoretical considerations have suggested that in hypercapnic respiratory failure there is interconversion of glutamic acid to glutamine within the brain, perhaps as part of a local buffering mechanism to minimize hypercapnia-induced cerebral acidosis. Detection of transcerebral arteriovenous differences, positive for glutamic acid and negative for glutamine, would lend support to this hypothesis. We measured arterial and internal jugular venous levels of twenty-three aminoacids in four patients with hypercapnic respiratory failure and in four suitable controls. In patients, arterial as well as venous glutamine levels were elevated proportionally, and there was no demonstrable A-V difference across the brain; arterial and venous glutamic acid levels were the same as controls. All other aminoacid levels, arterial and venous, were normal. These findings confirm the previous observations that in hypercapnic respiratory failure glutamine metabolism is altered, but provide no support for the proposed glutamic acid-glutamine interconversions within the brain.

Computed tomography vs standard radiology in the evaluation of mediastinal adenopathy

The value of computed tomography (CT) compared with standard radiology (SR) in the evaluation of mediastinal nodes has not been clearly defined. We compared SR and CT findings with the surgical-pathologic observations in a prospective study of 51 mediastinal nodes in 59 patients, 41 with bronchogenic carcinoma and 18 with benign lung lesions. CT was characterized by a low overall accuracy (true positivity plus true negativity = 60 percent) due to the false positivity (6 percent) and, to a much greater extent, the false negativity (51 percent). The pattern was the same in the malignant and in the benign group. In all instances CT findings were statistically the same as SR findings. We conclude that mediastinal CT provides no advantage over SR. Thus, SR alone is sufficient to select the surgical procedure of choice for evaluating mediastinal nodes, and no radiologic modality should replace surgical exploration in staging mediastinal nodal pathology.

Plasma levels of false neurotransmitters across the brain in portal-systemic encephalopathy

Arterial and internal jugular venous levels of false neurotransmitters (FNTs: octopamine, OCT, and phenylethanolamine, PEA), aromatic and branched-chain amino acids, glutamine, ammonia, and pH were measured in patients with portal-systemic encephalopathy (PSE) and in appropriate controls to define the role of these parameters in the pathogenesis of hepatic coma. The typical plasma patterns reported in the literature were observed: hyperammonaemia (59 +/- 8 mumol/l v. controls 30 +/- 4, P less than 0.005), elevated OCT (19 +/- 3 nmol/l v. 6 +/- 1, P less than 0.001) and PEA (64 +/- 8 nmol/l v. 27 +/-3, P less than 0.001), high ratio of aromatic to branched-chain amino acids (0.92 +/- 0.12 v. 0.32 +/- 0.04, P less than 0.005), and variable glutamine levels 216-734 mumol/l). No consistent net flux into or out of the brain could be demonstrated for any of these substances. The degree of encephalopathy correlated with the level of respiratory alkalosis (r=0.325, P less than 0.05) which, in turn, correlated with the degree of elevation of plasma OCT (r=0.439, P less than 0.05) and PEA (r=0.489, P less than 0.05) as well as with the excess of glutamine efflux from the brain (r=0.927, P less than 0.05). These findings support current views that hyperammonaemia, plasma amino acid imbalance, and elevated production of FNTs are interrelated disturbances which contribute to the pathogenesis of PSE. In addition, the data suggest that alkalosis accentuates the altered metabolism of these substances within the brain.

Duodenal crypts

During the course of 2,340 barium examinations of the upper gastrointestinal tract, four male patients were found to have multiple small outpouchings on the surface of the duodenal bulb. These findings, designated duodenal crypts, are considered to be asymptomatic and are not to be confused with inflammatory changes. The endoscopic and roentgenologic appearances are illustrated.

Duodenal crypts

During the course of 2,340 barium examinations of the upper gastrointestinal tract, four male patients were found to have multiple small outpouchings on the surface of the duodenal bulb. These findings, designated duodenal crypts, are considered to be asymptomatic and are not to be confused with inflammatory changes. The endoscopic and roentgenologic appearances are illustrated.

Optimal visualization of esophageal varices

Twelve patients with known esophageal varices and willingness to cooperate were included in the study. Medications administered were placebo, 2 mg of glucagon, and 30 mg of propantheline bromide. All medications were given double-blind and crossover. On the basis of this study the authors believe that for optimal visualization of esophageal varices the following is the procedure of choice: (1) the patient should remain horizontal (this is best done in the left lateral position for comfort and ease of expectoration) for ten minutes after swallowing high density barium; (2) the patient should "clear his throat" frequently and expectorate all saliva (barium sticks to the pharynx and makes the patient want to swallow and "clearing his throat" by forced expiration helps the patient to expectorate this coating and prevents swallowing); (3) filming should be done in expiration in the supine (left posterior oblique to table top) position; and (4) in equivocal cases the examination can be repeated with an anticholinergic drug if the patient has no contraindications to its use. The patient should empty his bladder just before administration of the drug. The intelligent use of these factors should result in a saving of both fluoroscopic time and film, and give the radiologist a safe optimal diagnostic yield.