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Biomedical subjects

B S Lewis

Publications and source records attributed to B S Lewis.

At least 109 records · Page 6Linked to original sources
PubMed1988

Usefulness of a rapid initial increase in plasma creatine kinase activity as a marker of reperfusion during thrombolytic therapy for acute myocardial infarction.

This study evaluates a new nonangiographic marker of reperfusion--a rapid initial increase in plasma creatine kinase (CK) and CK-MB activity--in 50 patients receiving intracoronary streptokinase. Blood for CK and CK-MB activity was sampled at 30-minute intervals and angiography performed at 15-minute intervals or earlier if there were clinical signs suggestive of reperfusion. An absolute first-hour increase in CK activity of 480 +/- 345 IU/liter (range 54 to 1,440 IU/liter), or a relative first-hour increase of 34 +/- 18% (range 13 to 67% of the peak rise), or an absolute first-hour increase in CK-MB activity of 48 +/- 36 IU/liter (range 10 to 144 IU/liter) or a relative first-hour increase of 27 +/- 13% (range 13 to 57%) was found in patients immediately after reperfusion with Thrombolysis In Myocardial Infarction (TIMI) grade 3 perfusion of the artery of infarction. The onset of rapid increase in CK and CK-MB activity closely reflected the time of angiographic documentation of reperfusion. In contrast, in the absence of reperfusion, the absolute rate of increase in CK activity measured in the last hour of the 2 1/2-hour period beginning with the start of treatment was only 15 +/- 9 IU/liter on the average (range 2 to 30 IU/liter) and the relative rate of rise was 3 +/- 2% on the average (range 1 to 6%).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Circulation↗
PubMed1988

Persistent painless ST-segment depression after exercise testing and the effect of age.

The relation between the duration of ischemic ST-segment depression (1 mm or more 60 ms after the J point) and the clinical awareness of chest pain was studied in 31 patients (aged 39-73 years) undergoing symptom-limited, graded treadmill exercise testing. The response of these patients to nitrate therapy (spray or sublingual tablet) given immediately on cessation of exercise was also studied. During exercise, angina pectoris appeared at an estimated workload of 4.6 +/- 2.2 metabolic equivalents (METS) (mean +/- SD), and pathological ST-segment depression at 4.9 +/- 1.9 METS (p = NS.) On cessation of exercise, angina disappeared after 3.0 +/- 1.9 min, but ST-segment depression persisted for more than twice as long (6.6 +/- 4.1 min) (p less than 0.0001). The ratio of time to ST-segment recovery/time to relief of pain (a quantitative measure of silent ischemia during recovery) increased with age (r = 0.49, p = 0.002), and in 16 patients over 60 years of age was higher than in 15 younger patients (3.6 +/- 2.5 vs. 2.1 +/- 1.4) (p less than 0.04). The silent ischemia ratio after exercise tended to decrease, although not significantly so (p = 0.2), in patients who received oral nitrates; there was no difference in the response to spray or tablet in this regard. We conclude that ST-segment depression frequently persists after relief of exercise-induced angina pectoris and more so in elderly patients.

Administration, Sublingual↗
PubMed1988

The lost polyp: a guide to retrieval during colonoscopy.

Polyps resected during colonoscopy should be recovered and sent for pathologic examination. Unfortunately retrieval is incomplete ranging from 85-100% in reported series. There are several specific techniques aimed to increase the retrieval rate which in our experience amounted to 94.5% of a series of 182 polypectomies in 100 consecutive patients. All lost polyps were small and were thought to have been aspirated through the suction channel of the endoscope. In our study 10% of the initially "lost" polyps were within the instrument prior to cleaning. Various forms of polyp retrieval are reviewed with special attention to locating the aspirated polyp.

Colonic Polyps↗
PubMed1988

Effect of the second-generation calcium channel blocker nisoldipine on left ventricular contractility in cardiac failure.

We studied the acute effects of nisoldipine, a new second-generation calcium channel-blocking drug, on cardiac hemodynamics and left ventricular (LV) contractility in 10 patients with grade 2 to 4 cardiac failure. Pressures were measured from an arterial line and a flow-guided catheter in the pulmonary artery, cardiac output by thermodilution, and LV ejection fraction simultaneously by radionuclide ventriculography. Ventricular loading conditions were altered by sublingual nitroglycerin to facilitate construction of LV end-systolic pressure (radial stress)-volume and stress-shortening curves. Nisoldipine, given by continuous intravenous infusion (0.12 micrograms/kg/min), reduced mean arterial pressure (p = 0.001), systemic vascular resistance (p less than 0.05), and the double product, a measurement of myocardial oxygen demand (p less than 0.01). Cardiac index, stroke index, and LV ejection fraction increased in 8 of the 10 patients. LV contractility was initially greatly reduced and was unchanged or slightly decreased during the administration of nisoldipine. Emax, the slope of the end-systolic pressure-volume curve, was unaltered in half of the patients and decreased in the others (NS), whereas the end-systolic stress-shortening curve did not change. In summary, nisoldipine has a potentially useful acute hemodynamic profile in patients with cardiac failure; it increases forward blood flow in most patients, decreases the determinants of myocardial oxygen demand, and produces little measurable changes in the inotropic state of the left ventricle.

Aged↗
PubMed1988

The major metabolite of bendazac inhibits the glycosylation of soluble lens proteins: a possible mechanism for a delay in cataractogenesis.

Glucose-6-phosphate and galactose react non-enzymically with lens proteins. The rates of these reactions are decreased by 5-hydroxybendazac but not by its parent compound, bendazac. Both bendazac and its major metabolite bind to lens proteins, mostly by non-covalent interactions. These results are discussed in relation to the use of bendazac as an anti-cataract drug.

Animals↗
PubMed1988

Chronic gastrointestinal bleeding of obscure origin: role of small bowel enteroscopy.

The source of blood loss remains undetermined in 5% of patients with chronic gastrointestinal bleeding. A new technique of small bowel enteroscopy with a prototypic sonde-type enteroscope 9 ft in length was used to examine 60 patients referred to the hospital with gastrointestinal bleeding of obscure origin. With an average procedure time of 6 h, the enteroscope migrated to the ileum or beyond in 77% of patients. Thirty-three percent (20 of 60 patients) had the source of blood loss identified within the small bowel at enteroscopy. Small bowel enteroscopy is a useful tool in patients with chronic gastrointestinal bleeding of obscure origin and can be considered when standard invasive and noninvasive modalities have failed to diagnose a site of bleeding.

Adult↗
PubMed1988

Synergistic effect of captopril and dobutamine on left ventricular pressure-volume and pressure-shortening relations in severe cardiac failure.

The acute effects of captopril and dobutamine, alone and in combination, on left ventricular contractility were assessed from left ventricular end-systolic pressure-volume and pressure-shortening relations in 6 patients with severe end-stage cardiac failure. Dobutamine was given by constant intravenous infusion on two occasions 48 hours apart, on one of these occasions the patient also received oral captopril in a dose of 37 +/- 12 mg 6-hourly. Pressures and cardiac index were measured, and left ventricular volumes and ejection fraction computed from simultaneously recorded radionuclide ventriculography. Dobutamine alone did not cause a statistically significant increase in stroke index, stroke work index, cardiac index and ejection fraction, although pulmonary capillary wedge pressure and right atrial pressure fell (P less than 0.05). There was no change in systemic or pulmonary vascular resistance nor in arterial blood pressure. Following administration of captopril, diastolic arterial pressure decreased (P less than 0.05), and the dobutamine challenge produced a greater and significant rise in stroke and stroke work index (P less than 0.05) and cardiac index (P less than 0.01). The left ventricular contractile state was unaltered by captopril but appeared to increase with dobutamine and more so during combined therapy with captopril and dobutamine, indicating a synergistic effect of the two drugs when given in combination.

Aged↗
PubMed1988

Short- and long-term results of angioplasty for multiple coronary stenoses.

Sixty-eight patients underwent percutaneous transluminal coronary angioplasty (PTCA) for multiple coronary stenoses. Lesions involved one coronary vessel in 24 patients, two in 34, and three or more vessels in 10 patients. The primary patient success rate was 96%, and we successfully dilated 162 (91%) of 179 significant (i.e., greater than 70% obstructive) coronary lesions, mean 2.4 lesions/patient. Complete coronary revascularization was achieved in 24 patients (Group 1), while major narrowings were not dilated either by intention or due to failure of dilation in 42 others (Group 2). The clinical state of the patients improved markedly after successful PTCA, and 44 (72%) of 61 were in the New York Heart Association Functional Class I or II 3 to 24 months later. In keeping with the clinical results, there was a significant improvement in treadmill exercise performance, in both groups. Patients with complete revascularization, however, tended to exercise longer (NS) to a greater heart rate (P less than 0.004) with less or no ischemic ST depression on ECG (P less than 0.04). Complications were few and limited to patients undergoing PTCA for unstable angina pectoris or following acute myocardial infarction. One patient (1%) died, two (3%) had Q-wave infarction and one patient sustained a cerebral embolus during catheterization. Restenosis was observed in 6 (29%) of 21 consecutive patients recatheterized 6 to 12 months (or sooner for symptoms) after successful PTCA. Four patients underwent a repeat PTCA, one was referred for coronary artery bypass grafting (CABG), and in one restenosis was minor and symptoms were mild. PTCA should be considered in patients with multiple coronary stenoses in whom all or most of the significant lesions can be dilated. Partial revascularization by PTCA is clinically useful and may be preferable to CABG in patients in whom the surgical risk is increased.

Adult↗
PubMed1988

Advantage of combined therapy with captopril and nitrates in severe congestive heart failure.

We compared the acute hemodynamic effects of captopril and nitrates in 11 patients with severe congestive heart failure and Grade IV cardiac disability. Pressures were measured using a Swan-Ganz catheter system; cardiac output and stroke index were measured by thermodilution, and left-ventricular (LV) volumes and ejection fraction were calculated simultaneously with the hemodynamic measurements from radionuclide ventriculography. Measurements were made in each of four treatment states: control, sublingual isosorbide dinitrate (ISDN) (5 and 15 mg), oral captopril (50 to 200 mg daily) and during combined therapy with captopril and ISDN. Captopril produced a fall in mean arterial pressure (P less than 0.01) from 81 +/- 14 to 72 +/- 13 mm Hg, and a rise in stroke index from 30 +/- 5 to 35 +/- 91/min per m2 (P less than 0.05), while LV ejection fraction increased from 18 +/- 5 to 21 +/- 7% (P less than 0.05). ISDN reduced mean arterial, pulmonary arterial, right-atrial and wedge pressure. The combination of captopril and ISDN produced a greater fall in mean arterial pressure, a further rise in ejection fraction to 22 +/- 8% (P less than 0.05), a fall in systemic (P less than 0.05) and pulmonary vascular resistance (P less than 0.01) and a rise in cardiac (P less than 0.01) and stroke work index (P less than 0.01), while the beneficial effects of ISDN on right-atrial, pulmonary arterial and wedge pressure were again achieved. LV contractility, assessed from end-systolic stress-shortening relations, was essentially unaltered or decreased very slightly. The study showed that combined therapy with captopril and nitrates produced acute hemodynamic benefits superior to those achieved by treatment with captopril or nitrates alone.

Blood Pressure↗
PubMed1988

Small bowel enteroscopy in 1988: pros and cons.

Endoscopic visualization of the small bowel is now feasible with a recently developed long, small-caliber, transnasal endoscope. Previously, with standard instruments, endoscopic views of the small intestine were limited to the most proximal and distal portions or required laparotomy and intraoperative endoscopy. Small bowel enteroscopy with the new transnasal sondetype flexible endoscope now allows most of the small bowel to be examined as a relatively short, ambulatory procedure. The literature pertaining to endoscopic evaluation of the small intestine is reviewed.

Endoscopes↗
PubMed1988

Small colon polyps.

One thousand forty-eight small (up to 6 mm) colorectal polyps, removed during colonoscopy, have been analyzed. Sixty-one percent of these small polyps were neoplastic, the remainder being equally divided between hyperplastic polyps and polypoid mucosa with normal-appearing glands. The number of polyps was evenly distributed throughout the colon. Proximally, neoplastic polyps predominated, accounting for 73% of all polyps in the right colon. This was reversed in the distal colon where non-neoplastic polyps comprised 65% of all polyps in the rectum. The incidence of carcinoma was extremely low in small colon polyps, 0.1%. All polyps should be removed when encountered during colonoscopy due to the high prevalence of adenomas among small colon polyps.

Adult↗
PubMed1988

Air accidents, pilot experience, and disease-related inflight sudden incapacitation.

The epidemiology of sudden death, the etiology of inflight sudden incapacitation, and the influence of pilot age and experience on air accident rates are reviewed in order to determine the aeromedical emphasis needed to minimize accidents. Sudden deaths in men over age 35 are nearly all due to coronary artery disease, whereas in those under 35 years they are mostly due to hypertrophic cardiomyopathy. The incidence of fatal accidents from human error is, however, far greater than that from physical illness. Since inexperienced pilots have a 2-3 times increased incidence of mishaps due to pilot error, the estimated risk of disease related in-flight sudden incapacitation should be balanced by consideration of pilot experience. Therefore, it may be preferable to grant waivers to experienced pilots with an increased incidence of disease-related inflight sudden incapacitation than to replace them with novices. We conclude that overly strict medical criteria may paradoxically increase accident rates.

Accidents, Aviation↗
PubMed1987

Efficacy of a two-hour infusion of 150-mg tissue plasminogen activator in acute myocardial infarction.

Forty-two patients with acute myocardial infarction received 150-mg recombinant human tissue-type plasminogen activator (rt-PA) at 2.3 +/- 1.2 hours after the onset of chest pain. After a 40 U/kg bolus of heparin, rt-PA was given as a 10-mg bolus followed by a 2-hour continuous infusion of 90 mg in the first hour and 50 mg in the second hour. Nonangiographic signs of reperfusion occurred during treatment (41 +/- 21 minutes) in 35 patients and in 1 other patient about 30 minutes after rt-PA. Three patients had discordant nonangiographic signs of reperfusion, 2 patients had no evidence of reperfusion and 1 patient in cardiogenic shock died before completion of the rt-PA infusion and before reperfusion status could be ascertained. Clinical signs of early reocclusion occurred in 4 of the 36 patients with evidence of reperfusion, 3 of whom were retreated with rt-PA with clinical success in 2. Coronary angiography 10 +/- 8 hours later revealed a patent artery of infarction in 35 patients: 32 with nonangiographic signs of sustained reperfusion, both patients with successfully treated reocclusion and 1 of 3 patients with discordant signs of reperfusion. Angiography revealed evidence of partial reperfusion in the remaining 2 patients with discordant signs, and an occluded artery was found in both patients without any evidence of reperfusion and in both patients with clinical signs of persistent reocclusion. Hemorrhagic complications occurred in 9 patients, 7 were related to procedural trauma and 2 patients required a blood transfusion. Four patients died, each of a cardiac cause: 3 in hospital and 1 at home.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗