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Biomedical subjects

L W Stevenson

Publications and source records attributed to L W Stevenson.

At least 127 records · Page 7Linked to original sources
PubMed1989

Diverse mechanisms of unexpected cardiac arrest in advanced heart failure.

To define the mechanisms of unexpected cardiac arrest in advanced heart failure, we reviewed the causes of cardiac arrest as established from electrocardiographic monitoring and from clinical and autopsy data in patients hospitalized for cardiac transplantation evaluation and management of advanced heart failure (mean left ventricular ejection fraction, 0.18 +/- 0.08) who were stable while on vasodilator and diuretic therapy such that hospital discharge to home was anticipated. Twenty-one cardiac arrests occurred in 20 of 216 (9%) such patients during a 4-year period. Heart failure was due to coronary artery disease with prior myocardial infarction in 13 patients and nonischemic cardiomyopathy in seven patients. The rhythm at the time of arrest was severe bradycardia or electromechanical dissociation (BA/EMD) in 13 (62%) patients. The precipitating cause of the BA/EMD arrest was coronary artery thrombosis or embolism in two patients, pulmonary embolism in one patient, hyperkalemia in two patients, and unexplained hypoglycemia in one patient. In seven of 13 (54%) patients, a precipitating cause of the bradycardia arrest could not be established. Only eight of 21 (38%) arrests were due to ventricular tachycardia or fibrillation (VT/VF), and all occurred in patients with prior myocardial infarction (p = 0.02 vs. BA/EMD arrests). Two VT/VF arrests were due to acute or recent infarction, and one patient had hyperkalemia. The patients who suffered a BA/EMD arrest were similar to those who had a VT/VF arrest in age, ventricular arrhythmia history, ventricular function, and serum potassium levels. Serum sodium levels were lower in patients with BA/EMD arrests (129 +/- 3 vs. 133 +/- 4 meq/l, p = 0.025).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Heart transplantation may not improve quality of life for patients with stable heart failure.

Heart transplantation is a therapeutic option for many patients with end-stage heart failure. Vigorous medical therapy has evolved so that many patients eligible for heart transplantation can now be discharged and stabilized with medical therapy. Heart transplantation improves survival, but it has not been compared previously with sustained medical therapy with regard to quality of life. We compared quality of life for 24 patients who survived at least 6 months after heart transplantation with that for 20 patients clinically similar at baseline who survived at least 6 months with sustained medical therapy. Quality of life was assessed by using three questionnaires. Both groups were similar in psychosocial functioning, with patients receiving medical therapy reporting greater dysfunction in social activities, as compared with those who underwent heart transplantation. No differences were seen in 6-minute walking distances and employment status. Survival benefits are expected with heart transplantation; however, quality of life for survivors may not be different than that for patients who survive with sustained medical therapy.

Female↗
PubMed1988

Inducible ventricular arrhythmias and sudden death during vasodilator therapy of severe heart failure.

Sudden death is common in patients with severe heart failure, but antiarrhythmic drug therapy has potential risks as well as benefits. Programmed electrical stimulation may offer a means of identifying lower risk patients who are less likely to benefit from antiarrhythmic therapy and who could potentially be spared the risk of adverse drug effects. Therefore 72 consecutive patients referred for management of severe heart failure (left ventricular ejection fraction 0.18 +/- 0.06) were studied. The mean age was 47 +/- 12 years; 45 (61%) patients had idiopathic dilated cardiomyopathy and 24 (33%) had coronary artery disease. Fifty-eight (82%) patients had nonsustained ventricular tachycardia. Following adjustment of vasodilators and diuretics, programmed stimulation was performed from the right ventricular apex with one, two, and three extrastimuli. Sustained ventricular tachycardia was initiated in nine (13%) patients and all received chronic antiarrhythmic drug therapy. During follow-up of 176 +/- 187 days, 1 of 13 patients treated for inducible ventricular tachycardia and 13 of 63 noninducible patients died suddenly (p = 0.20). The actuarial risk of sudden death in the noninducible patients was 13% at 6 weeks and 30% at 6 months. The only independent predictors of sudden death were pulmonary artery systolic pressure greater than 55% mm Hg and a pulmonary capillary wedge pressure with vasodilator therapy greater than 16 mm Hg. Of the 63 noninducible patients, 11 (17%) received long-term antiarrhythmic agents due to atrial fibrillation or referring physician preference, and antiarrhythmic therapy was not associated with a lower risk of sudden death in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Monocyte migration into the subendothelial space of a coculture of adult human aortic endothelial and smooth muscle cells.

Human aortic endothelial cells (EC) and smooth muscle cells (SMC) were isolated and used to form a multilayer of EC-SMC separated by a layer of collagen. SMC and/or collagen layers exerted minimal effects on Na+ transport but impeded the transport of LDL. The presence of an endothelial monolayer markedly reduced the transport of Na+ and LDL. When monocytes were presented to the complete coculture, in the absence of added chemoattractant, one monocyte entered the subendothelial space for every one to three EC present. In contrast, neither collagen nor SMC plus collagen nor EC plus collagen induced comparable monocyte migration. Despite massive migration of monocytes into the coculture, no significant alteration in Na+ transport was observed. LDL transport into the preparation during massive monocyte migration increased modestly, but this was far less than the amount of LDL transported in the absence of an endothelial monolayer. We conclude that (a) the endothelial monolayer was the principal permeability barrier, (b) a substantial migration of monocytes occurred in the absence of added chemoattractant when both EC and SMC were present in the coculture, (c) endothelial barrier function was largely maintained after monocyte migration; and (d) these experiments indicate the need to study all three cell types (monocytes, EC, and SMC) together to understand the complex interactions that occur between these cells.

Adult↗
PubMed1988

The dilated cardiomyopathies: clinical aspects.

The dilated cardiomyopathies are characterized by an increase in left ventricular internal dimensions without an appropriate increase in ventricular wall thickness. The myocardial injury often goes unrecognized until the offending cause is no longer apparent. Although specific diagnoses and treatment can sometimes be established, the majority of cases are designated idiopathic but are believed to result from previous viral infections, autoimmune or genetic predisposition, or abnormalities of the coronary microvasculature. Despite impaired contractility and ventricular dilatation, compensated dysfunction may prevail for some time. Excessive fluid retention, neurohumoral activation, systemic vasoconstriction, and atrioventricular valve regurgitation promote progressive hemodynamic deterioration. The meticulous matching of diuretic and vasodilator therapy to specific hemodynamic goals, particularly the normalization of ventricular filling pressure, frequently allows restoration and maintenance of reasonable functional capacity even in patients with severe heart failure. Nevertheless, sudden death due to ventricular arrhythmias and occasionally to systemic emboli remains a major threat. Prophylactic use of antiarrhythmic agents and anticoagulant therapy is not of proven efficacy. Cardiac transplantation results in significant improvement in life expectancy for patients with dilated heart failure but is available only to a relatively small number of patients because of the limited donor supply. Accordingly, programs providing cardiac transplantation should be equally committed to providing optimal medical management that is the only option for the majority of patients with dilated cardiomyopathy.

Adolescent↗
PubMed1988

Cardiac transplantation. Selection, immunosuppression, and survival.

Cardiac transplantation has evolved from an experiment to an accepted therapy for severe heart failure. Increasing competition for donor organs mandates a greater emphasis on selection and timing for transplantation and paradoxically forces more reliance on aggressive medical therapy for all patients after evaluation. The growth of recipient and donor pools may enhance the opportunity for assessing histocompatibility, for which distinguishing between autoantibodies and human leukocyte antigen-determined reactivity is important, and some general nonresponders may be detected. Therapy with cyclosporine has improved the outcome after transplantation, but further refinement is needed, perhaps with pharmacologic synergy, to minimize nephrotoxicity and maximize specific immunosuppression. Survival is more than 80% at 1 year, after which the incidence of acute rejection and infection declines and accelerated atherosclerosis becomes prominent. Although resuming employment is not always possible, the overall quality of life is excellent after cardiac transplantation.

Cyclosporins↗
PubMed1987

Effects of afterload reduction (diuretics and vasodilators) on left ventricular volume and mitral regurgitation in severe congestive heart failure secondary to ischemic or idiopathic dilated cardiomyopathy.

The mechanism by which afterload reduction increases left ventricular stroke volume while decreasing left ventricular filling pressure has not previously been established. In 15 patients with severe congestive heart failure due to ischemic or idiopathic dilated cardiomyopathy, absolute ventricular volume, ejection fraction and total stroke volume from radionuclide ventriculography were compared with thermodilution stroke volume before and after intensive afterload reduction with vasodilators and diuretics titrated to hemodynamic goals. After 48 to 72 hours, pulmonary artery wedge pressure decreased from 32 +/- 8 to 16 +/- 4 mm Hg and systemic vascular resistance from 1,960 +/- 700 to 1,200 +/- 400 dynes s cm-5. End-diastolic volume decreased from 390 +/- 138 to 301 +/- 126 ml (p less than 0.01) and end-systolic volume from 316 +/- 127 to 241 +/- 111 (p less than 0.01). Ejection fraction did not change and total stroke volume decreased from 74 +/- 22 to 59 +/- 20 ml (p less than 0.01). Simultaneous forward stroke volume by thermodilution increased from 37 +/- 14 to 52 +/- 14 ml (p less than 0.01), and forward fraction increased from 0.55 +/- 0.40 to 0.96 +/- 0.42. Intensive reduction of ventricular filling pressure and systemic vascular resistance decreased total ventricular stroke volume by 20% but increased forward stroke volume by 40%. The major effect of intensive afterload reduction for severe congestive heart failure may be the reduction of ventricular volume and mitral regurgitation.

Blood Pressure↗
PubMed1987

Mitral regurgitation after cardiac transplantation.

The contribution of the left atrium to mitral valve competence was assessed using the model of altered atrial size and geometry created by atrial anastomosis during cardiac transplantation. Sixteen patients underwent Doppler and 2-dimensional echocardiography after orthotopic transplantation. Mitral regurgitation was present in 14 of 16 patients. Left atrial geometry was uniformly abnormal, in a "snowman" configuration. Compared with 16 normal control subjects, the transplanted left atria were dilated (23 +/- 6 vs 13 +/- 3 cm2 during ventricular systole, p less than 0.001). Mitral valve anular diameter indexes, anular systolic reduction and ventricular function were normal in both groups. Ventricular volumes were small in the transplanted heart relative to donor body size (15 +/- 5 vs 20 +/- 8 cm3/m2 in systole, p less than 0.05). The ratio between ventricular length and anular diameter was smaller in the transplant patients (0.87 +/- 0.1 vs 1.0 +/- 0.2, p less than 0.05). In the presence of abnormal left atria, mitral regurgitation may occur without other structural abnormalities of the mitral apparatus. This study suggests that the left atrium plays an important role in mitral valve competence for primary cardiac disease associated with left atrial enlargement, even in the absence of intrinsic mitral valve disease or left ventricular dysfunction.

Echocardiography↗
PubMed1987

Predictability of mitral regurgitation detected by Doppler echocardiography in patients referred for cardiac transplantation.

Mitral regurgitation (MR) is common in patients with congestive heart failure (CHF), but the frequency in relation to the origin of ventricular dilatation has not been established. In 50 patients referred for cardiac transplantation, MR was assessed by Doppler echocardiography and the findings were compared with clinical information. Dilatation of the left ventricle, left atrium and mitral anulus was analyzed in 25 patients with respect to cause of CHF. All 50 patients had MR of at least moderate severity, regardless of cause (idiopathic dilated cardiomyopathy in 36, coronary artery disease in 14), length of symptoms (20 +/- 19 months, less than 6 months in 13 patients) or presence of murmurs (absent in 13 patients). Comparison of patients with nonischemic cardiomyopathy to those with ischemic heart disease revealed larger left ventricular volumes (215 +/- 81 vs 131 +/- 60 ml in systole, p less than 0.05) and left atrial volumes (124 +/- 70 vs 70 +/- 35 ml, p less than 0.05). Mitral anular dilatation was present only in patients with idiopathic cardiomyopathy (diameters 3.6 +/- 0.4 vs 3.1 +/- 0.2 cm, p less than 0.05). The frequency of significant MR in these patients with CHF suggests that it may have a major role in decompensation and in the therapeutic response.

Adolescent↗
PubMed1987

Poor survival of patients with idiopathic cardiomyopathy considered too well for transplantation.

Although the success of cardiac transplantation has encouraged earlier referral of potential candidates, those with mild symptoms of heart failure are frequently considered "too well" for transplantation. Outcome was investigated for 28 patients with non-ischemic dilated cardiomyopathy and ejection fraction of 25 percent or less who were denied transplantation due to lack of severe symptoms. One-year survival without transplantation was 46 percent. Low stroke volume and history of ventricular arrhythmias were independent predictors of early mortality. High risk, defined as either stroke volume of 40 ml or less or history of ventricular arrhythmia, identified 13 of 14 patients who did not survive one year and only one of 12 one-year survivors (p less than 0.001). Low stroke volume predicted hemodynamic failure (p less than 0.05) whereas arrhythmic history predicted sudden death (p less than 0.001). Clinical status improved in only six patients, all of whom had symptom duration of seven or less months at initial evaluation (p less than 0.001). Thus, patients referred to transplantation for dilated cardiomyopathy with an ejection fraction of 25 percent or less have a poor prognosis even if symptoms are mild. Patients with high hemodynamic risk may require early transplantation, whereas those with high arrhythmia risk may require other aggressive therapy in order to avoid transplantation until symptoms become severe.

Cardiomyopathy, Dilated↗
PubMed1987

Postdefibrillation idioventricular rhythm--a salvageable condition.

While patients who present with a pulseless idioventricular rhythm have a dismal prognosis, such a rhythm following electrical defibrillation from ventricular fibrillation (VF) may have an entirely different clinical significance. By reviewing the cases of 100 consecutive patients with prehospital ventricular fibrillation, we found the following: Subsequent development of field pulses, survival to hospital admission and hospital discharge in 49 patients who initially had pulseless idioventricular rhythm following defibrillation were statistically significantly worse (P<.05) than for 20 patients successfully defibrillated into any other organized rhythm. They were statistically significantly better, however, than for 25 patients who failed to achieve any organized rhythm in the field. Outcomes were statistically no different in 40 patients who received standard advanced cardiac life support drug therapy for pulseless idioventricular rhythm after defibrillation than in 9 patients who spontaneously progressed to another rhythm before drug therapy could be given. These findings suggest that pulseless idioventricular rhythm may be a transient recovery rhythm following defibrillation from prehospital VF, that it can in this circumstance be associated with a good outcome in a reasonable number of patients and that a short trial of cardiopulmonary resuscitation only, without immediate drug therapy, may be appropriate in these patients.

Arrhythmias, Cardiac↗
PubMed1986

Maintenance of cardiac output with normal filling pressures in patients with dilated heart failure.

Therapy of elevated ventricular filling pressures in patients with dilated heart failure may be limited by concern that cardiac output will be further compromised. Twenty-five patients with severe symptoms and ejection fractions of 25% or less were studied to determine the lowest ventricular filling pressures that could be achieved with vasodilator and diuretic therapy while maintaining cardiac output. In 20 of 25 patients normal pulmonary capillary wedge pressures (PCWs) were achieved (mean 10 mm Hg compared with 30 mm Hg at baseline). Stroke volume was 60 vs 39 ml at baseline. Stroke work index was 30 vs 19 g-m/m2. For each patient, over the range of PCWs, stroke volume and stroke work index were maintained and were often maximal at the lowest PCW achieved. The upright position was well tolerated in patients with normal supine PCW. Normal filling pressures can be achieved in patients with congestive heart failure without compromise of cardiac output. While congestive symptoms should be improved, the feasibility and benefit of maintaining normal filling pressures over a long term must be established.

Cardiac Catheterization↗
PubMed1984

Incidence and significance of early pericardial effusions after cardiac surgery.

Echocardiography (echo) is frequently performed postoperatively to evaluate patients suspected of having cardiac tamponade or pericarditis. The overall incidence and significance of echocardiographic pericardial effusions (PE) early after cardiac surgery are unknown. Therefore, M-mode and 2-dimensional (2-D) echo were used to study 39 stable patients 4 to 10 days after cardiac surgery. Twenty-two patients (56%) had unequivocal moderate-to-large PEs. PEs were identified on serial chest x-rays in only 6 patients. PEs were significantly more common after heavy postoperative bleeding, and occurred in 16 of 19 patients with more than 500 ml of total chest tube output; only 6 of 20 patients with chest tube output less than 500 ml had PE. There was no correlation of PE by echo with pericardial friction rubs, chest pain or atrial arrhythmias. Elevated erythrocyte sedimentation rate did not correlate with PE by echo or clinical pericarditis. In 1 of 22 patients with PE, tamponade developed, and the patient required reoperation on day 5; the other 21 were discharged without related therapy. Thus, early postoperative PEs are common and related to postoperative bleeding. Because they do not correlate with symptoms of pericarditis and rarely lead to tamponade, their identification is usually of limited clinical significance.

Adult↗
PubMedDate not supplied

Sexual function in patients with advanced heart failure.

OBJECTIVES: To determine the effect of low ejection fraction on sexual function and the relation between alterations in sexual function and pertinent clinical, demographic, and psychosocial variables in patients with advanced heart failure. DESIGN: This study was descriptive and correlational in design. SETTING: The setting was an outpatient clinic of a university-affiliated hospital. SUBJECTS: Sixty-two male (82%) and female (18%) patients with advanced heart failure (New York Heart Association [NYHA] class III or IV) were studied. MEASURES: Exercise tolerance and symptom severity were assessed by the 6-minute walk and NYHA classification. Ejection fraction was measured by echocardiography. Alterations in the patients' emotional, social, and sexual function were assessed with the self-report version of the Psychosocial Adjustment to Illness Scale. RESULTS: Approximately three quarters of the patients reported a marked decrease in sexual interest and in the frequency of sexual relations caused by illness, with one quarter having ceased all sexual activity. Half the patients described having experienced marked reductions, after heart failure developed, in the pleasure or satisfaction they normally experienced from sex. Few patients had arguments with their spouses about sex or reported significant marital problems as a result of their illness. A significant relation was documented between patients' sexual function and the results of the 6-minute walk (r = 0.32, p < 0.005), as well as between sexual function and NYHA functional class (r = 0.21, p < 0.05). Sexual function was also related to the patient's social environment (r = 0.59, p < 0.001), psychologic distress (r = 0.38, p < 0.001), and domestic environment (r = 0.29, p < 0.05). No significant differences in sexual function were noted when patients were compared on the basis of differences in ejection fraction, medications, gender, or age. CONCLUSION: Advanced heart failure results in marked changes in libido and in the ability to perform sexually. These changes do not affect the marital relationship negatively, at least in the view of the patient. As patients' symptoms of heart failure become increasingly more severe, physicians and nurses need to counsel patients and their spouses about the changes they may experience in their sexual relationships. Attention needs to focus on ways to cope with the decreasing physical status that accompanies advanced heart failure to minimize negative changes in sexual functioning.

Age Factors↗
PubMedDate not supplied

Initial success of steroid weaning late after heart transplantation.

Steroid-free maintenance immunosuppression is frequently initiated early after transplantation. There is concern that later steroid withdrawal, particularly after previous rejection, may cause more serious rejection. To determine the safety of gradual weaning from steroid maintenance, 68 patients (more than 6 months from transplantation) were weaned from 5 mg/day by decreasing the daily dose by 1 mg each month, with monthly biopsies. Asymptomatic moderate rejection occurred in 13 compliant patients. Rejection with hemodynamic compromise occurred in two patients with documented medication noncompliance, who were excluded from further analysis. Successful weaning without rejection was possible in 53 of 66 (80%) compliant patients. Compared with the rejection group, there were no differences in the number of women, previous rejection episodes, or time from transplantation. All moderate rejection episodes responded to oral steroid pulse therapy. The two serious rejections after noncompliance responded to OKT3. There were no symptoms from steroid withdrawal that required taper alteration. We conclude that regardless of previous rejection episodes, weaning from maintenance steroids can be attempted safely if guided by frequent biopsy procedures, but compliance is critical.

Biopsy↗