Low back and neck pain in locomotive engineers exposed to whole-body vibration

The objective of this study was to determine the prevalence and excess risk of low back pain and neck pain in locomotive engineers, and to investigate the relationship of both with whole-body vibration exposure. A cross-sectional survey comparing locomotive engineers with other rail worker referents was conducted. Current vibration levels were measured, cumulative exposures calculated for engineers and referents, and low back and neck pain assessed by a self-completed questionnaire. Median vibration exposure in the z- (vertical) axis was 0.62 m/s(2). Engineers experienced more frequent low back and neck pain, odds ratios (ORs) of 1.77 (95% confidence interval [CI]: 1.19-2.64) and 1.92 (95% CI: 1.22-3.02), respectively. The authors conclude that vibration close to the "action levels" of published standards contribute to low back and neck pain. Vibration levels need to be assessed conservatively and control measures introduced.

Coronary arteriography in 486 patients--arteriographic pathology and prognosis

The coronary arteriographic findings and prognosis in a series of 486 non-surgically treated patients were analyzed. A semiselective injection was used. The number and causes of deaths were obtained from the census registry after a follow-up period of 7--12 years. The material comprised normal arteriograms in 26% of the patients, wall irregularities at most in 17%, obstruction of at least half the diameter in 37%, and unclassifiable arteriograms in 19%. A mean of 1.8 obstructed arteries per patient was found in the group with obstructive arterial lesions and among these patients the left anterior descending artery was most often engaged. In the same group the cardiac mortality at seven years was 20%. There were no significant differences between deceased and survivors with regard to clinical data. The arteriograms themselves offered more information about the prognosis. Normal arteries or wall irregularities at most implied excellent prognosis with regard to death in coronary heart disease. The seven-year mortality was 36% among patients with coronary artery occlusions, which is significantly higher than 14% among those with arterial stenosis. Materials from the USA and Canada have displayed a much higher mortality than our study in spite of comparable arteriographic findings.

Unstable step meandering with elastic interactions

We report on theoretical investigations of the influence of step interactions due to elasticity on unstable step meandering during molecular beam homoepitaxy. It is shown that elasticity causes coarsening of the cellular structure of the meander found in a previous work. The time dependence of step roughness is found to be robust, behaving as t(1/2). The lateral length scale coarsening is shown to be sensitive to the underlying physical mechanisms. In particular, the typical length follows the law t(alpha), with alpha = 1/6 or 1/4 depending on whether line diffusion is negligibly small or not.

Sips, Sops, and SPIs but not stn influence Salmonella enteropathogenesis

The virulence factors influencing Salmonella-induced enteropathogenesis remain poorly characterised. The interactions of different serotypes of Salmonella with bovine ileal mucosa have been characterised in the ligated ileal loop model. In a quantitative intestinal invasion assay Salmonella dublin, S. choleraesuis, S. gallinarum, and S. abortusovis strains were all recovered from ileal mucosa, either with or without Peyer's patches in similar numbers. This observation suggests that the magnitude and route of intestinal invasion does not mediate Salmonella serotype host specificity. Despite being equally invasive there was a clear hierarchy in the enteropathogenicity of these serotypes. The magnitude of the enteropathogenic responses did not correlate to serotype host specificity. These observations implicate undefined serotype specific factors in influencing enteropathogenicity independently of intestinal invasion. Disruption of genes in Salmonella Pathogenicity Island (SPI) 1 of S. typhimurium and S. dublin blocked the secretion of Salmonella Invasion Proteins (Sips) and Salmonella Outer Proteins (Sops). These mutants were significantly less invasive and enteropathogenic then the wild type strain in ligated ileal loops. Disruption of sopB and sopD significantly reduced enteropathogenesis, but without influencing intestinal invasion. These two genes appear to act in concert. Surprisingly, disruption of stn, the Salmonella enterotoxin gene cloned on the basis of its homology to cholera toxin, did not influence enteropathogenesis. SopB was mapped to the 20 centisome of S. typhimurium and is flanked by 5 genes that are organised in a manner typical of a pathogenicity island, which we have termed SPI-5. Mutation of the other genes in SPI-5 also attenuated enteropathogenesis but not virulence for mice, suggesting SPI-5 is a key locus specifically influencing Salmonella enteropathogenesis.

Coronary arteries: breath-hold MR angiography

The authors describe a method for performance of ultrafast magnetic resonance (MR) angiography of coronary arteries with a standard clinical MR system and a body coil. Each image was obtained within a single breath hold by using an electrocardiography-gated, segmented, ultrafast, gradient-echo pulse sequence with an incremental excitation flip angle for the eight phase-encoding steps acquired per segment. By using overlapping 4-mm-thick sections, the coronary arteries were routinely depicted from the coronary ostia distally at MR in healthy subjects. Ultrafast MR angiography of the coronary arteries is feasible with use of a standard body coil. This technique offers considerable potential as an investigational tool and, with further development, may become a clinically useful imaging application.

First-pass nuclear magnetic resonance imaging studies using gadolinium-DTPA in patients with coronary artery disease

Nuclear magnetic resonance (NMR) imaging has been shown to accurately portray cardiac anatomy and function. To investigate the potential of NMR imaging for the assessment of coronary stenosis in patients with chest pain, ultrafast NMR imaging in conjunction with a T1 (longitudinal relaxation time) contrast agent was performed in 17 patients with chest pain who had undergone cardiac catheterization. These included 12 patients with significant coronary artery stenoses and 4 who underwent repeat NMR study after myocardial revascularization. Cardiac images at rest were obtained during rapid intravenous injection of gadolinium-DTPA (0.04 mM/kg). Electrocardiographic-gated images were acquired over 380 ms, with repetitive images obtained every 3 to 4 s. After contrast injection, there was pronounced signal enhancement in the right ventricular cavity, followed by enhancement in the left ventricular cavity and myocardium. Regional myocardium perfused by a diseased vessel demonstrated a lower peak signal intensity (p = 0.001) and lower rate of signal increase (p = 0.001) than did myocardium perfused by coronary arteries without stenosis. Repeat NMR study after revascularization showed an increase in peak signal intensity (p less than 0.002). These results demonstrate the clinical potential of dynamic gadolinium-DTPA-enhanced NMR imaging for the assessment of coronary artery disease in patients with chest pain. In combination with anatomic and functional NMR imaging, this technique has the potential to provide a comprehensive noninvasive cardiac evaluation of patients with suspected coronary artery disease.

MR imaging of the aortic root and proximal coronary arteries

Six patients who had recently undergone selective coronary and left ventricular angiography were prospectively examined with MR to show the aortic root and proximal coronary arteries. The examinations were performed with a superconductive 1.5-T instrument with spin-echo sequences and ECG-gated multiple slices of 5-mm thickness. The location and plane direction of the scan were guided by findings on initial coronary MR scout scans and by a review of the angiograms. In four of the six patients both coronary orifices and the proximal centimeters of both coronary arteries were identified. In the remaining two, only the left proximal coronary artery was seen. Although segments of more peripherally located portions of the main coronary arteries and branches were detectable, a prospective and conclusive identification without knowledge of the angiographic anatomy would have been extremely difficult. Differential diagnostic problems, such as erroneous interpretation of pericardial recesses and coronary veins, were observed. Unsuccessful demonstration of the right coronary artery orifice in two cases coincided with more peripherally located occlusion of the vessels on the angiogram. MR with spin-echo sequences appears to be unsatisfactory for diagnosis of coronary arteriosclerotic disease, but it may be useful in other conditions that result in significant coronary dilatation, such as fistulae and aneurysms.

Intracoronary thallium-201 scintigraphy after thrombolytic therapy for acute myocardial infarction compared with 10 and 100 day intravenous thallium-201 scintigraphy

Thallium-201 imaging has been utilized to estimate myocardial salvage after thrombolytic therapy for acute myocardial infarction. However, results from recent animal studies have suggested that as a result of reactive hyperemia and delayed necrosis, thallium-201 imaging may overestimate myocardial salvage. To determine whether early overestimation of salvage occurs in humans, intracoronary thallium-201 scans 1 hour after thrombolytic therapy were compared with intravenous thallium-201 scans obtained approximately 10 and 100 days after myocardial infarction in 29 patients. In 10 patients with angiographic evidence of coronary reperfusion, immediate improvement in thallium defects and no interim clinical events, there was no change in imaging in the follow-up studies. Of nine patients with coronary reperfusion but no initial improvement of perfusion defects, none showed worsening of defects in the follow-up images. Six of these patients demonstrated subsequent improvement at either 10 or 100 days after infarction. Seven of 10 patients with neither early evidence of reperfusion nor improvement in perfusion defects had improvement of infarct-related perfusion defects, and none showed worsening. In conclusion, serial scanning at 10 and 100 days after infarction in patients with no subsequent clinical events showed no worsening of the perfusion image compared with images obtained in acute studies. Therefore, there is no evidence that thallium-201 imaging performed early in patients with acute myocardial infarction overestimates improvement.

Uptake of hematoporphyrin derivative by valvular vegetations in experimental infective endocarditis

Drugs that localize in valvular vegetations may be useful in the diagnosis and treatment of infective endocarditis. We therefore tested the hypothesis that parenterally injected hematoporphyrin derivative (HPD), which is concentrated in tumors and atherosclerotic plaques, localizes in the vegetations of experimental infective endocarditis. In 14 rabbits, various bacteria were given intra-arterially immediately after injury to the aortic valve. In 12 additional rabbits, sterile vegetations on the aortic valve were produced by the trauma caused by an indwelling catheter that had been in place over a long period. HPD, 2.5 mg/kg, was injected intravenously 1 to 2 days before the animals were killed in six rabbits with sterile vegetations and in seven rabbits with infected vegetations. In all rabbits, multiple vegetations on the aortic valve leaflets were identified. On exposure to ultraviolet light, strong porphyrin fluorescence of all vegetations, whether sterile or infected, was observed only in rabbits given HPD. In two rabbits given HPD 10 weeks after catheter implantation across the aortic valve, however, only mild fluorescence could be detected in healing endocardial vegetations. In frozen sections of HPD-laden lesions, a patchy distribution of fluorescence was observed that was similar to the pattern of HPD localization in atheromatous plaques. Since vegetations in experimental infective endocarditis selectively concentrate HPD, porphyrins could be useful in the diagnosis and treatment of infective endocarditis.

Intracoronary thallium-201 assessment of thrombolysis in acute myocardial infarction. Validation of the method of imaging before and after therapy

In order to study acute changes in perfusion with intracoronary thrombolytic therapy, we have used ten times the pretherapy intracoronary thallium-201 dose for the posttherapy study. Because of the larger posttherapy dose, the posttherapy images had ten times as many counts as the pretherapy images. Since the change in image quality between the pretherapy and posttherapy studies might affect interpretation, we studied the effect of image statistics on interpretation of perfusion scintigraphy. The pretherapy and posttherapy images were scored on a four-point scale in five segments on each of three views. In 31 patients, Poisson-distributed pseudorandom noise was added to the posttherapy study in order to match the statistical accuracy of the pretherapy study. A blinded interpretation of the pretherapy and posttherapy noise-added images was performed in the same way as the initial unblinded interpretation. The mean difference between the unblinded pretherapy and posttherapy scores (the improvement in thallium distribution with therapy) was 2.5+/-0.8 (standard error) compared with the difference between the blinded pretherapy and posttherapy noise-added scores which was 2.6+/-1.0. The correlation between readings of similar pairs of data was higher than the correlation between pretherapy and posttherapy studies. Thus, the difference in statistic quality of the pretherapy and posttherapy studies did not affect the interpretation of these studies. Therefore, our evaluation of pretherapy and posttherapy studies using a ten-fold increase in thallium-201 dosage is valid.

Left ventricular wall motion analysis using operator-independent contour positioning

A method has been developed for the analysis of left ventricular wall motion which obviates the operator's involvement in the relative positioning of the systolic and diastolic contours. This was achieved by maximizing the cross-correlation function for the two silhouettes . The technique was compared with a standard method requiring the operator's definition of a long axis for the left ventricle. The results for 21 normal angiograms showed that with the cross-correlation technique the confidence region of the wall motion curves was markedly narrower and the symmetry in the contractile pattern between the anterior and posterior wall segments was better than with the standard technique. Statistical concepts for narrowing the normal group and the sources of errors in the analysis are discussed.

Computerized image analysis for quantitative measurement of vessel diameter from cineangiograms

Subjective estimates of the angiographic severity of coronary artery stenoses show variability and inaccuracy. We therefore tested the accuracy of a newly developed computerized image analysis system for quantitating vessel diameter from cineangiograms. Fourteen cylindrical phantoms of known diameter were filled with contrast medium and filmed over a wide range of clinically relevant radiographic conditions in order to develop regression equations that related computer-derived to anatomic diameters. Computer measurements of vessel diameter were unaffected by vessel size, magnification, focal spot size, thickness of scattering medium, kilovolt peak, or location within the radiographic field, but a correction factor was necessary for a small but significant (p less than .01) linear dependence on contrast medium concentration. The accuracy of computerized vessel diameter measurements ranged between +/- 59 and +/- 137 mu for all conditions except for rapid vessel motion and contrast medium concentrations of 50% or less meglumine diatrizoate (Renografin 76), both of which resulted in reduced accuracy as well as in the inability to locate lumen edges of vessels less than 1 mm in diameter.

In vivo coronary angioscopy

The feasibility of in vivo coronary angioscopy was tested utilizing a 1.8 mm angioscope in vessels where blood had been replaced by optically clear liquids, including a new perfluorocarbon emulsion. After trials in postmortem canine and human coronary arteries, in vivo intraluminal visualization was accomplished in the dog with a catheterization technique and in patients during open heart surgery. The results demonstrate the feasibility and potential clinical usefulness of direct visualization of intravascular anatomy and disease, analogous to endoscopy of other organ systems.

Fluorescence of experimental atheromatous plaques with hematoporphyrin derivative

Fluorescence of hematoporphyrin derivative (HPD) has been used clinically to localize malignant neoplasms because of its selective accumulation in these tissues. We tested the hypothesis that HPD may also be selectively concentrated within atheromatous plaques. 48 h after HPD injection in a variety of species, selective fluorescence of atheromatous plaques of the aorta was seen in each animal (rabbits and Patas monkey) exhibiting such lesions. No fluorescence could be demonstrated in aortic segments free of atheromatous involvement. Since the efficacy of photodynamic destruction of malignant tumors with HPD has been demonstrated in clinical studies, the observations of the present study may have therapeutic implications in atheromatosis.

The minimum error in estimating coronary luminal cross-sectional area from cineangiographic diameter measurements

A formal analysis of the error associated with the use of radiographic diameter measurements in estimating the luminal area of an elliptically-shaped coronary cross-section was performed. When two views are available, the maximum potential error was found to decrease rapidly as the angle between the views increased to 90 degrees, but this error was small (less than 25%) for orthogonal views only for mild degrees of ellipticity (major/minor axis ratio less than 2). Since, for each successive doubling of the number of radiographic views, a stepwise reduction in the potential error by an approximate factor of only one-half was found, a large number of views is required to eliminate the potential error associated with diameter assessment of highly elliptical lumena.

A catheterization technique for reproduction of a human atherosclerotic lumen within the dog coronary artery in vivo

Reproduction of a human atherosclerotic lumen within the arterial lumen of an intact animal would facilitate angiographic and hemodynamic studies of stenoses. Accordingly, a male silicone rubber cast of a human atherosclerotic lumen was obtained from a cadaver artery, and a thin-walled replicate arterial phantom was constructed from the cast by use of a rapidly polymerizing liquid plastic. The casting properties of both materials were such that the topography of the arterial lumen was duplicated precisely in the phantom with 20 x microscopic detail preserved. The phantom was coated with a banzalkonium-heparin solution and introduced over a guidewire into an epicardial segment of a coronary lumen of the dog. Similarly, a larger phantom was placed within the dog femoral artery either directly via an arteriotomy or indirectly via a catheterization technique. Since the plastic material used to make a phantom had the same radiographic density of tissue, the angiographic appearance of an intra-arterial phantom was that of a human stenosis.

Computer reconstruction of luminal cross-sectional shape from multiple cineangiographic views

Knowledge of coronary luminal shape, in addition to diameter information as routinely obtained from a cineangiogram, may be useful in assessing lesions which deviate from circular symmetry. We have developed an image analysis system for automated tracking of luminal edges and measurement of diameter form cine frames digitized by a video camera/digitizer interfaced to a Vax 11/780 computer. Between vessel edges, cinedensitometric profiles across the vessel long axis are used to provide a rotationally invariant measure of relative luminal cross-sectional area. A maximum entropy iterative algorithm is used to reconstruct the lumen cross section from a set of projection data consisting of the cinedensitometric profiles from multiple radiographic views. Nonaxisymmetric model coronary lumena, such as a crescent shape and a double lumen simulating a coronary artery dissection, were filmed under cineradiographic conditions similar to clinical exposures. Radiographic views at 10 degrees increments about the model lumen long axis over 360 degrees were available for analysis. Graphic display of reconstructed model lumena indicate that as few as three to five radiographic views may be useful in reconstructing coronary luminal shape.

Successful streptokinase treatment of a thrombosed, ectopic coronary artery: a case report

Early reperfusion of a thrombosed, ectopically arising coronary artery was accomplished by selective streptokinase infusion therapy. Familiarity with the most common variations of coronary artery orifices and/or divisions of major branches is important for the angiographer to ensure that selective catheterization of the involved artery can be accomplished promptly.

Experimental myocardial ischemia II: radiographic contrast media toxicity

The comparative effects of meglumine sodium diatrizoate (MSD), sodium meglumine calcium metrizoate (SMCM), and metrizamide (M) were studied in an isolated canine heart preparation. The parameters observed were coronary blood flow (CBF), myocardial contractile force (MCF), positive and negative dF/dt, and perfusion pressure during normal and ischemic perfusion conditions. MSD had an initial negative inotropic effect but baseline MCF returned in 1 min during normal perfusion and 2 min under ischemic conditions. SMCM and M had only a positive inotropic effect under normal perfusion. However, during ischemia, the positive effect of SMCM was followed by a decrease in contractile force. M showed only a positive effect on force during ischemia. Our results indicate that calcium additive may increase the risk of coronary arteriography in patients with severe coronary artery disease.

Functional alterations in the coronary circulation as mirrored in the angiogram

The ability of coronary arteriography to disclose the presence of abnormalities in the coronary arteries is undisputed. On the other hand, it is less clear whether the angiographic examination of the coronary circulation permits an assessment of functional abnormalities, which may involve the coronary circulation in toto or regionally. The most commonly practiced grading of angiographically demonstrated coronary artery disease is based on the degree of arterial narrowing and the number of major vessels that are involved. This approach, however, suffers from significant shortcomings, which are mainly related to the limitations in accuracy of measuring such lesions angiographically. Secondary angiographic signs of impaired coronary flow, such as contrast propagations through collateral channels, delayed, stagnant, and reciprocal flow pattern, and the appearance of excessive peripheral myocardial contrast accumulation may gain great importance. In conjunction with the presentation of a number of cases considered to be representative for different situations of chronic and acute myocardial ischemia, the primary and secondary angiographic findings are accounted for in detail and discussed as to the most likely existing pathophysiology. The discussion also includes knowledge based on experiments performed in in vitro or animal models and tries to establish a synthesis between the different angiographic phenomena and the present status of our understanding of the pathophysiology of myocardial injury. It is concluded that such detailed analysis of the angiographic events may yield important information for the most appropriate management of the individual patient.

Thrombogenicity of heparin- and non-heparin-coated catheters: clinical trail

Catheters used in clinical cerebral angiography were examined by scanning electron microscopy for buildup of thrombus. In 21 (67%) of 31 individuals studied with non-heparin-coated catheters, either cell aggregations or thrombi developed compared with seven (28%) of 25 individuals studied with heparin-coated catheters. The median size of the cell aggregations and thrombi on non-heparin- and heparin-coated catheters was significantly different (p less than 0.01). The slopes that estimated the probable rate of thrombus formation were also significantly different (p less than 0.01). This suggests the desirability of replacement of non-heparin-coated catheters if the angiographic procedure is extended.

Mortality related to cardiac catheterization and angiography

During a 14-month period, 75 deaths occurring in relation to 53,581 cardiac catheterizations were consecutively and prospectively reported to the Registry Committee of the Society for Cardiac Angiography. Three of the patients died several days after their catheterization from an unrelated cause and are excluded from this analysis. There were 21 patients (group I) who arrived at the laboratory in extremis and whose deaths were expected irrespective of the catheterization. Most of these patients suffered from recent myocardial infarctions and cardiogenic shock, or had complex congenital malformations. In 35 patients (group II), a cardiovascular complication occurring during the catheterization resulted in death. In 16 patients (group III) catheterization seemed uneventful, but death occurred suddenly 10 min to 10 h after the procedure. Of these 16 patients, eight had left main coronary artery obstruction greater than or equal to 90%, five had three-vessel disease all with 90% obstructions, one had 2-vessel disease both with 90% obstructions, and who had critical aortic stenosis. The 51 unexpected deaths (groups II and III) were considered to be causally related to the procedure, a mortality rate of 0.10%. Subsets with an increased mortality rate (M), were patients with: a) left main disease greater than 50% (M = 0.94%); b) ejection fraction less than 30% (M = 0.54%); c) NYHA class III or IV (m = 0.24%); d) age over 60 years (M = 0.23%); or e) three-vessel disease (M = 0.13%). In conclusion, catheterization related mortality occurs mostly in patients with far advanced cardiac disease. Nearly 1/3 of the unexpected deaths occurred suddenly after a seemingly uneventful procedure. Close monitoring after catheterization of patients with similar characteristics (left main disease greater than or equal to 90%, or three-vessel disease all greater than or equal to 90%) might disclose avenues for reducing mortality occurring after catheterization.

Myocardial salvage after intracoronary thrombolysis with streptokinase in acute myocardial infarction

Nine patients with acute myocardial infarction had cardiac catheterization and intracoronary infusions of streptokinase 2.3 to 4.3 hours (mean, 3.5) after the onset of symptoms. Occluded coronary arteries were opened within approximately 20 minutes in all patients, but reocclusion occurred in one patient. The immediate effect of thrombolysis on myocardial salvage was assessed with the intracoronary injection of thallium-201. Improved regional perfusion, indicating myocardial salvage after recanalization, was observed in seven of the nine patients. One patient, who had also sustained a nontransmural infarction one week before, had no change after thrombolysis. In the ninth patient, recanalization of a coronary artery was followed by reocclusion and worsening of the myocardial-perfusion defect. Intracoronary thallium-201 studies two weeks and three months after streptokinase infusion in two patients were unchanged in comparison with scintiscans performed 1.5 hours after thrombolysis. These short-term observations suggest that recanalization of obstructed coronary arteries after intracoronary thrombolysis can salvage jeopardized myocardium, However, evaluation of the long-term effects of this procedure on survival and myocardial function will require controlled clinical trials.

Effect of angiographic contrast agents on the mechanical performance of the isolated rat papillary muscle preparations

The effects of the radiographic contrast agents Renografin, Isopaque, and Hypaque on the mechanical performance of isometrically contracting rat papillary muscle was compared to a new contrast agent, Amipaque. It was found that exposure to Amipaque resulted in significantly less depression of contractile activity than any of the other agents. Changes in mechanical performance associated with exposure to Renografin, Isopaque, or Hypaque could not be attributed to either hypocalcemia or hypoxia. The decrease in developed tension and increase in resting tension was similar to that produced by Krebs-Henseleit containing hypertonic (1420 mmol) glucose or sucrose. Thus, the data support the concept that hyperosmolarity of the radiographic contrast agents may be primarily responsible for the adverse effects on mechanical performance of the myocardium associated with angiography.

Comparative effects of three radiographic contrast agents in isolated normal and ischemic canine hearts

Investigators have sought to improve contrast agents by changing the ionic content or decreasing osmolarity. This study compared the effects of meglumine sodium diatrizoate, sodium meglumine calcium metrizoate, and metrizamide on coronary blood flow, myocardial contractile force, and perfusion pressure under normal and ischemic conditions in eight isolated canine hearts. Diatrizoate had an initial negative inotropic effect, but contractile force returned to baseline within 1 minute during normal perfusion and within 2 minutes under ischemic conditions. Calcium-enriched metrizoate and metrizamide had only a positive inotropic effect under normal perfusion (127 +/- 3.9% and 116 +/- 2.9% of baseline, respectively). During ischemia, however, the positive inotropic effect of sodium meglumine calcium metrizoate was followed by a decrease in contractile force to 93 +/- 5% of baseline after 2 minutes. Metrizamide showed only a positive inotropic effect during ischemia. The myocardial depression that follows the initial positive inotropic effect of calcium may further alter the instability between normal and ischemic areas of the heart, thus increasing the risk of coronary arteriography in patients with severe coronary artery disease.

Crippled lung: variations on a theme by Macleod

We have studied nine male patients (age 18 to 68 years) with radiographic and physiologic evidence of an abnormally small lung on one side (three right and six left). All had had a childhood pneumonia or bronchiolitis and eight had chronic or recurrent bronchitis and exertional dyspnea. Radiography showed two of the small lungs to be hypolucent while seven were hyperlucent. Bronchography revealed evidence of bilateral chronic bronchitis in all with saccular bronchiectasis in three. Angiography showed strikingly diminished vascularity to the smaller lung. Spirometry revealed airway obstruction in seven of the patients. All had pulmonary arterial hypertension. Radiospirometry showed that the small lung had on the average 30% of the total ventilation but only 15% of the perfusion. Washout of 133 Xe was extremely slow in radiolucent regions. We suggest the name "crippled lung" syndrome for this entity because it is purely descriptive and encompasses several clinical variants. It also avoids the pitfalls of etiologic implication (acquired-congenital). Clinical or subclinical bronchitis seems to be common in these patients and the prime goal in therapy must be to combat the tendency towards airway infection.

Medically refractory unstable angina pectoris. I. Long-term follow-up of patients undergoing intraaortic balloon counterpulsation and operation

Of 82 patients with medically refractory unstable angina pectoris seen between October 1972 and January 1978, 60 patients underwent a combination of intraaortic balloon pump counterpulsation, cardiac catheterization and coronary revascularization. Most patients had atherosclerotic involvement of the vessels of the anterior left ventricular wall, 48 patients (80 percent) had abnormalities of left ventricular wall contraction and 22 patients (36 percent) had evidence of acute myocardial injury. One operative and one late death occurred. The perioperative infarction rate was 5 percent. Survivors, followed up for 3 to 63 months (mean 31 months), have done remarkably well; 77 percent are considered employable,and more than 90 percent are in functional class I or II.

Medically refractory unstable angina pectoris. II. Hemodynamic and angiographic effects of intraaortic balloon counterpulsation

Of 60 patients receiving intraaortic balloon counterpulsation for angina refractory to maximal medical therapy, a subgroup of 10 patients underwent left ventricular angiography both with and without counterpulsation. Severe stenosis of the left anterior descending coronary artery was present in all 10 patients. Counterpulsation resulted in a significant decrease in systolic and end-diastolic left ventricular pressures and no increase in cardiac index. Left ventricular diastolic and systolic volume, ejection fraction and regional contraction patterns, often abnormal, were unchanged. However, mean normalized systolic ejection rate was improved by the addition of counterpulsation. It is concluded that intraaortic balloon counterpulsation has relatively little effect on the left ventricular volume of patients with medically refractory angina pectoris. The symptomatic improvement that takes place seems to occur mainly through the effect of counterpulsation on preload and afterload.

Cine-densitometric measurement of coronary arterial stenoses

Computer-aided operator-interactive densitometry has been developed and applied to determine the percent stenosis for obstructive lesions in the coronary arterial tree. Phantom experiments performed to assess system linearity, accuracy of densitometric measurements, nonuniformity in image amplified response, and the interference of structure noise in measuring precision have been described. Three observers assessed the reproducibility of the method by repeating analyses on 20 stenoses in man recorded on 35-mm cine angiograms. Calculation of the intra- and interobserver errors found that their values significantly decrease with increasing percent stenosis. The reproducibility of the technique was also tested on stenoses that were exposed at multiple angles. The results agreed with those found for the intra- and interoperator errors. Limitations of the densitometric approach and desirability of further automation of the measurements are also discussed.