The Relationship Between Anti-SSA-52 and Interstitial Lung Disease

OBJECTIVE

The aims of this study were to assess whether a relationship between anti-SSA-52 and interstitial lung disease (ILD) can be further defined, and to enhance screening, detection, and potentially guide treatment.

METHODS

A historical cohort study of 201 patients was conducted at a single tertiary care center between January 1, 2016 and December 31, 2020. All included patients were anti-SSA-52 antibody positive. Chart review was performed for laboratory values, symptoms, pulmonary function tests, treatment, and imaging. Chest computed tomographies were reviewed by chest radiologists.

RESULTS

Among anti-SSA-52 antibody-positive patients, ILD was found in 125 (62.2%) compared with 76 (37.8%) with no ILD (p = 0.001). For those with ILD, 78 (62.4%) were diagnosed with connective tissue disease (CTD)-associated ILD, 28 (22.4%) were diagnosed ILD only, and 19 (15.2%) met the criteria for interstitial pneumonia with autoimmune features. In patients with CTD-ILD, 18 (23.0%) had their ILD diagnosis made over 6 months before a CTD diagnosis, and an additional 43 (55.1%) had their ILD and CTD diagnosed within 6 months of each other (p < 0.001). Common computed tomography patterns were nonspecific interstitial pneumonia/organizing pneumonia overlap in 44 (35.2%), 25 (20.0%) nonspecific interstitial pneumonia, and 15 (12%) usual interstitial pneumonia. Twenty-eight (35.9%) had antisynthetase syndrome, followed by 16 (20.5%) with dermatomyositis, 10 (12.8%) with CTD overlap, and 6 (7.7%) with systemic scleroderma.

CONCLUSIONS

There was a significant association between anti-SSA-52 antibodies and ILD across a wide spectrum of rheumatological diagnoses. A significant portion of patients were diagnosed with ILD either at the same time or before their CTD diagnosis. Further study will be needed to assess effective treatment and response.

The Utility of Bronchoscopy in Hydralazine-Induced ANCA-Associated Vasculitis

Hydralazine is a vasodilator used for the management of hypertension, heart failure, and hypertensive emergencies in pregnancy. It has been implicated in the causation of drug-induced lupus erythematosus (DLE) and rarely with ANCA-associated vasculitis (AAV), which may present as a pulmonary-renal syndrome and be rapidly fatal. Herein, we describe a case of hydralazine-associated AAV presenting as acute kidney injury with the use of early bronchoalveolar lavage (BAL) with serial aliquots to aid with diagnosis. Our case highlights how, in the correct clinical setting, BAL can act as a rapid diagnostic test to help guide quicker treatment to allow for better patient outcomes.

The Variation in Outcomes of Septic Patients: A Dual-Centre Comparative Study

Introduction Despite significant advances in the field of medicine, sepsis is constantly growing as a major public health concern. The global epidemic of sepsis imposes a significant economic burden on healthcare systems world-over. Furthermore, its high prevalence in society is inevitably paralleled by an excessive mortality rate, with approximately six million deaths reported every year. The primary aim of this study was to evaluate and compare, the management of acutely septic patients against outcomes in a tertiary teaching institution in Pakistan versus a similar one in the United Kingdom. Methods This study was a dual-centred, retrospective comparative analysis comparing all patients admitted through the emergency department at the respective tertiary centres. Patient details were collected and compared across the two sites to evaluate the effect of individual characteristics on prognosis. The outcomes of these presentations were analysed by comparing rates of in-hospital mortality, admission to the ICU or discharge. Results The total number of patients identified as having sepsis was 60 in the Pakistan cohort, and 92 in the Aberdeen cohort. No significant difference was found when comparing genders, and the results of basic observations were largely similar at presentation. Twenty-five per cent (25%) (n=38) of the total study population were deemed to have a poor outcome at 3 days, but 50% of the Pakistan cohort was deemed to have a poor outcome. Conclusion Managing sepsis has developed significantly in recent years, but most of this development was implemented in high-income countries. There was a significant delay in time to resuscitate septic patients in Pakistan, with significantly raised three-day morbidity and mortality. There is a need for further comparative studies of the management of sepsis in Pakistan and other low-income countries to identify the problems and tackle obstacles on every level of the healthcare system.

Negative Appendicectomy Rates in Females of Childbearing Age: A Retrospective Analysis and Literature Review

Introduction

A negative appendicectomy rate (NAR) is defined as the portion of pathologically normal appendices removed surgically in patients suspected of having acute appendicitis. The lifetime risk of acute appendicitis is 8.6% for males and 6.7% for females; contrarily, the lifetime risk of appendicectomy is 12% for males and 23.1% for females. This study aims primarily to evaluate the true NAR in females of childbearing age to offer insight into potential strategies to reduce the number of unnecessary operative procedures carried out, along with their associated morbidity and mortality.

Methods

All emergency appendicectomies over a one-year period were retrospectively identified and collected from a single tertiary care centre. Preoperative clinical, laboratory and postoperative histopathological data were collected. The negative appendicectomy rate in subgroups divided by biomarkers and radiological imaging findings were analysed. The diagnostic value of these modalities in the context of acute appendicitis was found by calculating the sensitivity, specificity, positive predictive values, and negative predictive values.

Results

A total of 417 patients were included (median age 26; M:F, 0.7:1.0). The overall negative appendicectomy rate was 35.0% (146/417). Two-hundred sixty-one patients underwent an appendicectomy in the child-bearing age group. The NAR was significantly higher in those females with raised WBC and C-reactive protein (CRP) compared to their male counterparts (p-value -<0.001).

Conclusion

Women of childbearing age have a higher NAR of 43% when compared to the general population of 35%. Preoperative tests, including ultrasound scans, computed tomography and inflammatory markers in blood tests, help direct those who would benefit from surgery to the operating theatre, however, no test alone is suitably sensitive or specific. To reduce the NAR, management options include a return to observation and serial examination, increased use of low-dose CT or a commitment to improving the performance of ultrasonography.

Multicentric analysis of the perceptions and knowledge of digital health amongst undergraduate medical students

INTRODUCTION

Digital health (DH) is continuously evolving by use of information and communications technology to improve healthcare provision, thereby reshaping systems and clinical practices. Recent studies identified an overwhelming lack of awareness of DH within the profession. This study aimed to analyse student perceptions and knowledge of DH to assess confidence in its use to develop greater DH awareness and literacy.

METHODS

Students enrolled in undergraduate medical degrees were invited to take part in an online survey assessing aspects of DH including demography, familiarity, attitudes, level of knowledge and confidence. Anonymised data was collated and subsequently analysed to review DH awareness.

RESULTS

A total of 143 students participated from nine British universities with 28.7% of respondents admitting low levels of familiarity of DH concepts. Students anticipated negative repercussions of DH including reduced data security (42.7%) and deterioration in doctor-patient relationship (30%); while improvements in healthcare access and health-outcomes are expected by 89.5% and 68.5%, respectively. 71.4% of participants believed they had minimal experience of exposure to DH and 76% believed they did not possess the necessary skills to utilise DH. Only 3.5% of students had some exposure to DH teaching during their course.

CONCLUSION

There is an important requirement to address the lack of knowledge and exposure of students to DH, particularly as the world targets the COVID-19 pandemic. DH is forming the basis of the 'new normal' in healthcare, however the full potential of DH cannot be achieved unless there is an increase in its teaching incorporated into medical school curricula.

Bilateral breast necrotizing leukocytoclastic vasculitis: First case report

Leukocytoclastic vasculitis (LCV) is a very rare immune complex-mediated condition affecting the small vessels walls. We present the case of a 48-year-old woman with necrotizing bilateral breast LCV on treatment with glatiramer acetate for multiple sclerosis. Bilateral mastectomies and debridement of the anterior abdominal wall were required due to the rapidly evolving necrotizing process. Rapid assessment and a multidisciplinary approach are fundamental in treating this rare life-threatening condition.

1123 An Audit of Pick-Up Rate of Random Colonic Biopsies

Aim

We aimed to evaluate optimal random biopsy criteria are being followed in our institution to increase the diagnostic yield of a subsequent histopathological examination and to reduce the number of unnecessary biopsies in which histopathology is unlikely to deliver clinically useful information and causing a burden on health resources in terms of cost and manpower.

Method

Our study was a retrospective on 419 random colonoscopy biopsies performed over 6 months. Data collection included variables such as age, gender, indications, request of urgency, and histology findings. Data analysis was done descriptively.

Results

Out of 419 random biopsies, only 10.02% had positive findings. The total number of histology results with microscopic colitis was 10. The main indication of the random colonic biopsy was a change in bowel habits (328 cases) followed by significant diarrhea greater than 50 years in 20 cases. In patients with a change in bowel habits, 2.44% of histopathology specimens revealed microscopic colitis. The percentage of random colonic biopsy histology in patients greater than 50 years with significant diarrhea showed microscopic colitis was 10%.

Conclusions

Our study revealed random biopsy during colonoscopy should only be done in selected patients otherwise it has low diagnostic yields biopsy and should only be reserved for patients with risk factors for optimum utilization of health resources and to reduce the cost burden. A scoring system may be helpful to risk-stratify patients in low and high risk for MC to determine which patients qualify for RCB.

An Unexpected Case of Posterior Reversible Encephalopathy Syndrome

This study presents an 86-year-old gentleman who was admitted under the acute stroke team for a possible posterior cerebral infarct. Radiologic imaging revealed that the diagnosis was in fact posterior reversible encephalopathy syndrome (PRES). Through a process of elimination by means of investigations, the most likely cause was found to be mild hypertension on a background of vascular dementia causing a possible exacerbation of PRES symptoms. A multidisciplinary approach was found to be beneficial, providing safe and effective care for this patient, allowing a brief recovery period and restoration of baseline function and thus minimising permanent sequelae.

The Analysis of Teaching of Medical Schools (AToMS) survey: an analysis of 47,258 timetabled teaching events in 25 UK medical schools relating to timing, duration, teaching formats, teaching content, and problem-based learning

BACKGROUND

What subjects UK medical schools teach, what ways they teach subjects, and how much they teach those subjects is unclear. Whether teaching differences matter is a separate, important question. This study provides a detailed picture of timetabled undergraduate teaching activity at 25 UK medical schools, particularly in relation to problem-based learning (PBL).

METHOD

The Analysis of Teaching of Medical Schools (AToMS) survey used detailed timetables provided by 25 schools with standard 5-year courses. Timetabled teaching events were coded in terms of course year, duration, teaching format, and teaching content. Ten schools used PBL. Teaching times from timetables were validated against two other studies that had assessed GP teaching and lecture, seminar, and tutorial times.

RESULTS

A total of 47,258 timetabled teaching events in the academic year 2014/2015 were analysed, including SSCs (student-selected components) and elective studies. A typical UK medical student receives 3960 timetabled hours of teaching during their 5-year course. There was a clear difference between the initial 2 years which mostly contained basic medical science content and the later 3 years which mostly consisted of clinical teaching, although some clinical teaching occurs in the first 2 years. Medical schools differed in duration, format, and content of teaching. Two main factors underlay most of the variation between schools, Traditional vs PBL teaching and Structured vs Unstructured teaching. A curriculum map comparing medical schools was constructed using those factors. PBL schools differed on a number of measures, having more PBL teaching time, fewer lectures, more GP teaching, less surgery, less formal teaching of basic science, and more sessions with unspecified content.

DISCUSSION

UK medical schools differ in both format and content of teaching. PBL and non-PBL schools clearly differ, albeit with substantial variation within groups, and overlap in the middle. The important question of whether differences in teaching matter in terms of outcomes is analysed in a companion study (MedDifs) which examines how teaching differences relate to university infrastructure, entry requirements, student perceptions, and outcomes in Foundation Programme and postgraduate training.

Exploring UK medical school differences: the MedDifs study of selection, teaching, student and F1 perceptions, postgraduate outcomes and fitness to practise

BACKGROUND

Medical schools differ, particularly in their teaching, but it is unclear whether such differences matter, although influential claims are often made. The Medical School Differences (MedDifs) study brings together a wide range of measures of UK medical schools, including postgraduate performance, fitness to practise issues, specialty choice, preparedness, satisfaction, teaching styles, entry criteria and institutional factors.

METHOD

Aggregated data were collected for 50 measures across 29 UK medical schools. Data include institutional history (e.g. rate of production of hospital and GP specialists in the past), curricular influences (e.g. PBL schools, spend per student, staff-student ratio), selection measures (e.g. entry grades), teaching and assessment (e.g. traditional vs PBL, specialty teaching, self-regulated learning), student satisfaction, Foundation selection scores, Foundation satisfaction, postgraduate examination performance and fitness to practise (postgraduate progression, GMC sanctions). Six specialties (General Practice, Psychiatry, Anaesthetics, Obstetrics and Gynaecology, Internal Medicine, Surgery) were examined in more detail.

RESULTS

Medical school differences are stable across time (median alpha = 0.835). The 50 measures were highly correlated, 395 (32.2%) of 1225 correlations being significant with p < 0.05, and 201 (16.4%) reached a Tukey-adjusted criterion of p < 0.0025. Problem-based learning (PBL) schools differ on many measures, including lower performance on postgraduate assessments. While these are in part explained by lower entry grades, a surprising finding is that schools such as PBL schools which reported greater student satisfaction with feedback also showed lower performance at postgraduate examinations. More medical school teaching of psychiatry, surgery and anaesthetics did not result in more specialist trainees. Schools that taught more general practice did have more graduates entering GP training, but those graduates performed less well in MRCGP examinations, the negative correlation resulting from numbers of GP trainees and exam outcomes being affected both by non-traditional teaching and by greater historical production of GPs. Postgraduate exam outcomes were also higher in schools with more self-regulated learning, but lower in larger medical schools. A path model for 29 measures found a complex causal nexus, most measures causing or being caused by other measures. Postgraduate exam performance was influenced by earlier attainment, at entry to Foundation and entry to medical school (the so-called academic backbone), and by self-regulated learning. Foundation measures of satisfaction, including preparedness, had no subsequent influence on outcomes. Fitness to practise issues were more frequent in schools producing more male graduates and more GPs.

CONCLUSIONS

Medical schools differ in large numbers of ways that are causally interconnected. Differences between schools in postgraduate examination performance, training problems and GMC sanctions have important implications for the quality of patient care and patient safety.

Comparison of hospital outcomes and resource use in acute COPD exacerbation patients managed by teaching versus nonteaching services in a community hospital

RATIONALE, AIMS, AND OBJECTIVES

The impact of teaching versus nonteaching services on outcomes and resource use in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is unknown. The aim of the study is to evaluate the impact of an internal medicine teaching service compared to a nonteaching service on outcomes and resource use in patients admitted with AECOPD in a community teaching hospital.

METHODS

A retrospective cohort study of patients admitted for a primary diagnosis of chronic obstructive pulmonary disease exacerbation to Florida Hospital Orlando, a large community teaching hospital, between January 1, 2011, and December 31, 2014. Data were extracted from Premier administrative database. Risk adjusted length of stay (LOS), cost of hospitalization, 30-day readmissions, and mortality rate were measured. Risk adjustment for outcomes was based on Premier CareScience methodology.

RESULTS

A total of 1419 patients were included, 306 in the teaching group and 1113 in the nonteaching group. Risk adjusted cost and LOS were significantly lower in the teaching group compared to the nonteaching group (observed/expected cost 0.66 vs 1.06, P < .001) and (observed/expected LOS 0.93 vs 1.69, P < .001), respectively. No significant difference was found between the 2 groups in risk adjusted mortality and readmissions (P = .48 and .89, respectively). Use of consults was significantly lower in the teaching groups with 73% vs 31% of the patient in the teaching group had no consults compared to the nonteaching group (P < .001). The teaching service was significantly associated with decreased use of consults after adjustment for other variables (odds ratio, 0.17, 95% CI, 0.15-0.23, P < .001).

CONCLUSION

The teaching service had more favorable outcomes compared to nonteaching services in patients hospitalized for AECOPD. The physician practice model has a major impact on the cost, LOS, and use of consults in patients with AECOPD.

Which tissue adhesive for wounds?

We studied the three available tissue adhesives comparing their ease of technique, wound healing, satisfaction, merits and complications when treating childhood lacerations. Children presenting with uncomplicated wounds <2.5cm and <6h since the injury were studied. There were 17 children in each group. Results were compared for the individual tissue adhesive and the technique-contact and non-contact. The application was considered pain free in 82% of the non-contact technique and 56% for the contact technique-pain in 18 and 44%, respectively (P=0.062). Parents were satisfied in 88 and 94% for the contact and non-contact techniques, respectively (P=0.505) and the authors in 76 and 94% (P=0.119). The glove stuck to the wound in nine instances and was damaged once while breaking the container. The scab persisted in all scalp applications for 9-25 days. The adhesive effect was similar in all three. Indermil was considered to be the best among the three. Non-contact, droplet instillation (rather than contact application as was suggested for Dermabond and Histoacryl) was felt more comfortable.

Isolated finger injuries in children--incidence and aetiology

Details were recorded prospectively in a specifically designed questionnaire for all children presenting to the Accident and Emergency Department with isolated finger injuries over a period of 6 months, in order to understand the incidence and aetiology. Among the 426 injuries in 283 children, most occurred at home (59%) more in the <5 year age group (38%), involving the middle finger (25%) and terminal phalanges (47%). "Jamming/crushing" was the commonest reason (48%), mostly caused by a child (59%) at the living room door (32%) and more commonly at the hinge side (49%). Nail injuries were seen in 48% of cases and 16 amputations of terminal phalanges were noticed in 15 children. Tendon injuries were only caused when cut by sharp objects, and were not caused by jamming/crushing. Both children and adults should be educated about causation, reiterating that damage to fingers can be prevented or reduced by observing safety measures.

Metal detector and swallowed metal foreign bodies in children

OBJECTIVE

To evaluate a metal detector to diagnose swallowed radio-opaque metal foreign bodies (MFBs) in children, and whether they can detect non-radio-opaque MFBs.

METHODS

In a prospective study, 231 children, who presented to the accident and emergency department with a history of swallowing MFBs, were evaluated by the metal detector as well as radiography to confirm and locate the presence or absence of MFBs.

RESULTS

A definite history of swallowing a MFB by the child was given by 186 (81%) parents. The metal detector located MFBs in 183 children and radiographs confirmed radio-opaque MFBs in 181. In the remaining 45 (19%), when swallowing was suspected and not definite, both metal detector and radiography confirmed the presence of a MFB in only four.

CONCLUSION

A high detection rate of swallowed MFBs was observed in this study, using a metal detector. It is also of value to detect non-radio-opaque MFBs like aluminium. The detection of MFBs is high when the history of swallowing is definite.

Ofloxacin compared with chloramphenicol in the management of external ocular infection

The safety and efficacy of 0.3% ofloxacin in treating bacterial ocular infections was compared with that of 0.5% chloramphenicol in a parallel-group, randomised clinical trial at five sites. Clinical and microbiological improvement rates were studied in 84 culture-positive patients. Patients with suspected bacterial ocular infections were evaluated for clinical improvement and were included in drug safety and comfort analyses. Clinical improvement did not differ significantly between drug treatments. All patients completing the study (79 assigned ofloxacin, and 74 chloramphenicol) showed clinical improvement. Clinical improvement in the culture-positive groups was 100% (41/41) after ofloxacin treatment, and 95% (41/43) after chloramphenicol treatment. Microbiological improvement rates were similar for the two drugs: 85% (33/39) improved with ofloxacin, and 88% (38/43) improved with chloramphenicol. Both drugs were well tolerated. Adverse reactions possibly due to the study medication occurred in 1% (1/89) of those who received ofloxacin, and in 4% (4/93) of those who received chloramphenicol.

Effects of exerimental right ventricular hypertrophy on myocardial blood flow in conscious dogs

The effects of right ventricular hypertrophy on the overall and regional distribution of myocardial blood flow in the absence of an elevated coronary arterial driving pressure were evaluated in 18 concscious dogs subjected to a chronic pressure overload of the right ventricle induced by pulmonary artery constriction. The sustained pressure overload for duration of 4--6 wk or 4--5 mo resulted in significant increases in right ventricular mass (45 and 110%, respectively) and right ventricular fiber diameter (22 and 60%, respectively). Moreover, the presence of moderate and severe hypertrophy was associated with marked increases in transmural blood flow per gram to the right ventricle proportional to the observed increases in mass, i.e., of 36 and 109%, respectively, from a normal value of 0.67 +/- 0.04 ml/min per g, whereas left ventricular blood flow remained unaltered from a normal value of 1.00 +/- 0.06 ml/min per g. Despite the large increase in blood flow per gram to moderately and severely hypertrophied right ventricle, no significant changes in the ratio of capillary:muscle fiber number were observe. These data suggest that the development of right ventricular hypertroph is characterized by a sustained compensatory response of the coronary circulation to the augmented work load and mass, and that is not associated with a proliferative response of the vasculature supplying the enlarged ventricle.

Prostaglandin control of the renal circulation in response to hypoxemia in the fetal lamb in utero

We studied the effects of 10-minute periods of hypoxemia in unanesthetized fetal lambs in utero instrumented for measurements of arterial pressure and renal and iliac blood flows. Fetal hypoxemia, induced by delivering a hypoxic gas mixture to the ewe, was characterized by a reduction in fetal PaO2 from 20.1 +/- 1.4 to 8.8 +/- 1.0 mm Hg (mean +/- SE). The fetus responded with bradycardia and persistent vasoconstriction in the iliac bed throughout the 10-minute period. In contrast, renal resistance rose significantly only at the end of the hypoxemic period. After 5-7 minutes of hypoxemia, when iliac flow had fallen by 40 +/- 4% and iliac resistance had risen by 86 +/- 13%, renal flow and resistance were not changed significantly from control; in fact, we found that renal flow rose substantially at this time in several fetal lambs. After blockade of prostaglandin synthesis with either indomethacin or meclofenamate, renal flow fell after 5-7 minutes of hypoxemia by 36 +/- 5%. The reduction in renal flow and increases in renal resistance were significantly greater than was observed prior to blockade of prostaglandin synthesis. Thus, fetal hypoxemia elicits bradycardia and intense peripheral vasoconstriction reflected by the changes in the iliac bed, with relative sparing of the reanl bed. The relative protection of the renal bed during fetal hypoxemia appears to be related to a mechanism involving prostaglandins, since after blockade of prostaglandin synthesis, hypoxemia results in intense renal vasoconstriction.

Measurement of multiple simultaneous small dimensions and study of arterial pressure-dimension relations in conscious animals

This paper describes the development of several important modifications that were incorporated into the ultrasonic, transit-time dimension system in order to obtain multiple simultaneous, instantaneous, and continuous measurements of the external dimensions of the aorta and its major branches in conscious, unrestrained animals. At operation a pair of small piezoelectric crystals was sutured to arterial adventitia, and a miniature pressure gauge was implanted in the vessel at the same cross-sectional plane. After recovery from surgery, wall motion was not altered appreciably and scarring was minimal. This technique allows long-term monitoring of aortic pressure-dimension relations and is applicable for small (fetal and neonatal) as well as large (adult dogs and sheep) animals. When vessel wall thickness is measured, stress-radius analysis can be performed so as to compute vascular elastic stiffness as a function of stress. Moreover, the suitability for radiotelemetry of the pressure and dimension signals measured with this technique enables the study of these parameters in unrestrained animals, e.g., during spontaneous severe exercise.

Effects of a cardiac glycoside on regional function, blood flow, and electrograms in conscious dogs with myocardial ischemia

We studied the effects of coronary occlusion and of subsequent ouabain administration on regional myocardial function, flow, and electrograms in 14 conscious dogs. Coronary occlusion resulted in a graded loss of regional function as reflected by measurements of segment length (SL), velocity of SL shortening and myocardial "work" from the normal to severely ischemic zones, along with graded flow (radioactive microsphere technique) reductions and graded elevation of the regional S-T segment. Ouabain, 20 microgram/kg, improved function in the normal zone, in which stroke shortening rose by 0.23 +/- 0.07 mm (mean +/- SE) and "work" rose by 30.2 +/- 9.5 mm Hg-mm. In moderately ischemic segments, stroke shortening rose by 0.60 +/- 0.05 mm and "work" rose by 58.1 +/- 6.1 mm Hg-mm. In the majority of severely ischemic segments, stroke shortening and "work" also increased; the average effect in all severely ischemic segments was an increase in stroke shortening of 0.35 +/- 0.10 mm and in "work" of 31.5 +/- 9.9 mm Hg-mm. In addition, ouabain reduced S-T elevation by 0.90 +/- 0.20 mV in moderately ischemic zones and by 3.14 +/- 0.35 mV in severely ischemic zones, and increased flow by 28 +/- 6% and 46 +/- 9% in moderately and severely ischemic zones, respectively. All these changes were significant, P less than 0.01. Thus, ouabain caused an improvement in perfusion of ischemic tissue, which was associated with significant enhancement of stroke shortening and "work." Most strikingly, ouabain returned normal systolic shortening to 10 severely ischemic segments which previously were akinetic.

Initial myocardial adjustments to brief periods of ischemia and reperfusion in the conscious dog

The changes in left ventricular (LV) dynamics induced by brief periods of ischemia (100 seconds) and subsequent reperfusion were analyzed in conscious dogs. Global LV ischemia, induced by partially occluding the left main coronary artery, reduced LV flow homogeneously and impaired LV function as reflected by decreases in LV stroke "work" (89 +/- 4% M +/- SE), systolic shortening (72 +/- 4%), velocity of shortening (56 +/- 6%), LV systolic pressure (34 +/- 5%), and dP/dt (59 +/- 6%). Regional LV ischemia, induced by occluding either the left circumflex or anterior descending coronary artery completely, reduced flow to the ischemic segment (82 +/- 3%) while decreasing segment work (96 +/- 5%), shortening (82 +/- 3%), and velocity of shortening (70 +/- 5%), with minimal depression of overall LV function. In both groups the extent of shortening was reduced more rapidly and greater (P less than 0.01) than shortening velocity. Moreover, with localized ischemia, segment work was reduced more (P less than 0.01) than shortening. With reperfusion, a transient overshoot in function above preischemic control levels was observed in both groups (global work increased by 60 +/- 12% and regional work by 28 +/- 4% above control). This overshoot was not dependent on adrenergic mechanisms, but was prevented by inhibiting reactive hyperemia. Thus myocardial ischemia induces a dissociation between extent and rate of myocardial shortening. A further dissociation between shortening and work is apparent with regional ischemia. After reperfusion there is a transient overshoot in function which appears to be dependent upon the associated reactive hyperemia.

Depression of regional blood flow and wall thickening after brief coronary occlusions

The effects of a 15-min coronary occlusion and subsequent reperfusion were investigated in conscious dogs previously instrumented for measurement of left ventricular pressure, dP/dt, regional wall thickening, electrograms, and myocardial blood flow. Coronary occlussion reduced overall left ventricular function only slightly but eliminated systolic wall thickening in the ischemic zone and reduced regional myocardial blood flow in the ischemic zone from 1.04 +/- 0.04 to 0.27 +/- 0.02 ml/min per g and the endo/epi flow ratio from 1.23 +/- 0.04 to 0.44 +/- 0.04, while S-T segment elevation increased from 1.1 +/- 0.3 to 8.2 +/- 0.9 mV. After release of the occlusion, S-T segment elevation disappeared within 1 min while reactive hyperemia in the previously occluded artery and a transient increase in cardiac diastolic wall thickness occurred and then subsided by 15 min. In contrast, systolic wall thickening and the endo/epi flow ratio remained significantly depressed for more than 3 h. Thus reperfusion after a 15 minute coronary occlusion results in a prolonged period of reduced regional myocardial blood flow, particularly in the endocardial layers, which correlates with the prolonged depression of regional myocardial shortening and wall thickening.

Effects of coronary artery reperfusion on myocardial infarct size calculated from creatine kinase

The effects of coronary artery reperfusion at 1 and 3 h after occlusion on infarct size (IS) in the conscious dog were compared with a second group of dogs that were not reperfused (24 h occlusion). Infarct size was calculated from creatine kinase (CK) appearing in blood samples (IS(s)) and myocardial CK depletion (IS(m)), and determined from gross and histological inspection of the pathological tissue (IS(p)). Under both conditions, IS(m) correlated well with IS(p). In dogs with 24-h coronary occlusions, IS(s) correlated well with IS(m) (IS(s) = 14.26 + 1.18 x IS(m), r = 0.92). In reperfused dogs, the relationship remained linear but was altered (IS(s) = 15.33 + 2.07 x IS(m), r = 0.89). The slope was significantly greater, P <0.05, than that observed for dogs that were not reperfused, suggesting that more CK appeared in serum per gram of infarct. Similarly, significantly different relationships were observed in the reperfused and nonreperfused dogs, when IS(s) was compared with IS(p). Moreover, the configuration of the serial blood CK curve was changed significantly by reperfusion. In dogs with a 24-h occlusion, CK rose gradually to a peak at 11.4+/-0.5 h. In dogs reperfused at 3 h, CK rose sharply at 3 h and reached a peak at 6.8+/-0.5 h, significantly earlier (P <0.01) than occurred in dogs reperfused at 1 h, i.e., when the peak occurred at 4.2+/-0.4 h. The rapid appearance of CK in blood after reperfusion at 1 and 3 h suggested a washout phenomena. Thus, reperfusion alters the shape of the serial blood CK curve and results in a different linear relationship between calculated and measured infarct size, resulting in greater recovery of CK in blood per unit of infarcted myocardium.

Effects of a cardiac glycoside in combination with propranolol on the ischemic heart of conscious dogs

The effects of coronary occlusion and of subsequent propranolol and ouabain administration were examined in 12 conscious dogs. Overall left ventricular (LV) function was assessed by measurement of LV pressure and dP/dt, and regional myocardial function was assessed by measurements of segment length (SL), velocity of SL shortening and regional myocardial "work," i.e., pressure-length loops in normal and moderately and severely ischemic zones. Regional intramyocardial electrograms were measured at the same sites as function along with regional myocardial blood flow as determined by the radioactive microsphere technique. Coronary occlusion resulted in graded loss of function from the normal to severely ischemic zones, along with graded flow reductions and graded elevation of the ST segment. Propranolol, 1 mg/kg, depressed overall LV function and function in the normal zone more than in ischemic zones. Propranolol reduced flow to the normal zone and increased flow to ischemic zones, while not affecting ST-segment elevation significantly. In the presence of occlusion and propranolol, ouabain, 20 microgram/kg, improved overall LV function as well as regional function in the normal, moderately ischemic and severely ischemic zones. In addition, ouabain reduced ST elevation and increased blood flow further in moderately and severely ischemic zones. Most strikingly, ouabain returned normal systolic shortening to eight severely ischemic segments which were previously akinetic.

Effects of propranolol on regional myocardial function, electrograms, and blood flow in conscious dogs with myocardial ischemia

The effects of coronary occlusion and of subsequent propranolol administration were examined in 18 conscious dogs. Overall left ventricular (LV) function was assessed by measurements of LV pressure and dP/dt, and regional myocardial function was assessed by measurements of segment length (SL), velocity of SL shortening and regional myocardial "work", i.e., pressure-length loops in normal, moderately, and severely ischemic zones. Regional intra-myocardial electrograms were measured from the same sites along with regional myocardial blood flow as determined by the radioactive microsphere technique. Coronary occlusion resulted in graded loss of function from the normal to severely ischemic zones with graded flow reduction and graded elevation of the ST segment. Propranolol depressed overall LV function, function in the normal zone (work fell by 17+/-4%), and in the majority of moderately ischemic segments (work fell by 7+/-3%). In severely ischemic segments the extent of paradoxical motion and post-systolic shortening was reduced by propranolol. After propranolol regional myocardial blood flow fell in the normal zone (11+/-2%) and rose in the moderately (15+/-4%) and severely (63+/-10%) ischemic zones. Thus, in the conscious dog with regional myocardial ischemia, propranolol induces a redistribution of myocardial blood flow, with flow falling in normal zones and rising in moderately and severely ischemic zones. The improvement in perfusion of ischemic tissue was associated with slight but significant depression of shortening, velocity, and work in the moderately ischemic zones and of paradoxical bulging and post-systolic shortening in the severely ischemic zone.

Cardiovascular effects of radioactive microsphere suspensions and Tween 80 solutions

The cardiovascular effects of two concentrations of Tween 80 (polyoxyethylene sorbitan mono-oleate), a surface-active agent commonly used to prevent aggregation of radionuclide-labeled microspheres, were examined in conscious dogs. Two types of adverse reactions were noted. The first (Type A) consisted of reductions in cardiac dimensions as well as hypotension and tachycardia. The second (Type B) was less severe and involved only a decrease in cardiac dimensions with no change in left ventricular systolic pressure or heart rate. A 10% dextran solution with .05 +/- .02% Tween 80 injected into the left atrium caused systemic and/or cardiac alterations in all four dogs studied. Administration of a lower concentration of Tween 80 (0.01 +/- 0.005%), which was the minimum concentration necessary to prevent aggregation of microspheres, induced adverse reactions in 6 of 41 dogs studied. Subsequent administration of this concentration of Tween 80 on the same day rarely induced adverse reactions. Thus, care must be exercised in application of microsphere techniques to organ blood flow measurements when Tween 80 is used to prevent microsphere aggregation, since this surface-active agent causes profound alterations in cardiac dynamics in concentrations normally employed in experiments involving microsphere techniques.