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Biomedical subjects

D I Silverman

Publications and source records attributed to D I Silverman.

At least 37 records · Page 2Linked to original sources
PubMed1995

Prevalence of residual left atrial thrombi among patients with acute thromboembolism and newly recognized atrial fibrillation.

BACKGROUND: Thromboembolism related to atrial fibrillation (AF) is a major cause of morbidity and mortality. Patients with acute thromboembolism and AF are at high risk for early recurrent events. OBJECTIVE: To determine the prevalence of left atrial thrombi in patients who had acute thromboembolism and newly diagnosed AF. PATIENTS AND METHODS: Adult inpatients with AF were screened to identify those with acute (< 36 hours) systemic thromboembolism and newly recognized AF. Of 41 qualifying patients, 31 (76%) agreed to undergo transesophageal echocardiographic study, including 24 with acute neurologic events and seven with peripheral thromboembolism. A control population consisted of 88 adults with newly recognized AF without clinical thromboembolism. RESULTS: Transesophageal echocardiography identified left atrial thrombi in 13 (43%) of the 30 study patients who underwent transesophageal echocardiography compared with nine (10%) of 87 controls (P < .001). Spontaneous echo contrast was identified in 27 (87%) of the study population vs 42 (48%) of controls (P < .001). The prevalence of this marker of blood stasis did not differ between patients with left atrial thrombi without thromboembolism (P = .69). Duration of AF, prevalence of abnormal left ventricular function, left atrial size, and mitral regurgitation were similar in both groups. CONCLUSIONS: Left atrial thrombi were identified in more than 40% of patients with acute thromboembolism and newly recognized AF. These data suggest that a major source of recurrent thromboembolism in this group may be residual thrombus migration. Among patients with AF and atrial thrombi, clinical thromboembolism seems to occur randomly, or is related to an unidentified process.

Acute Disease↗
PubMed1995

Cardioversion of nonrheumatic atrial fibrillation. Reduced thromboembolic complications with 4 weeks of precardioversion anticoagulation are related to atrial thrombus resolution.

BACKGROUND: The use of warfarin anticoagulation for several weeks before cardioversion results in a 90% reduction in the incidence of cardioversion-related thromboembolism. The mechanism of this benefit, however, is unknown; it has been widely attributed to organization and adherence of atrial thrombi, a finding observed among pathological studies of patients with rheumatic valvular disease. METHODS AND RESULTS: Serial transesophageal echocardiography was performed in 14 patients with nonrheumatic atrial fibrillation after identification of atrial thrombi on initial transesophageal study. All patients received warfarin anticoagulation and were followed clinically for signs of thromboembolism. Eighteen atrial thrombi were identified on initial transesophageal study, including 14 thrombi confined to the left atrial appendage, 2 in the body of the left atrium, 1 in the right atrial appendage, and 1 in the body of the right atrium. Thrombus size varied from 5 to 20 mm, and 6 were considered mobile. After a median of 4 weeks of warfarin, 16 of 18 atrial thrombi (89%; 95% CI, 73% to 100%) had completely resolved on transesophageal echocardiographic study. In addition, no new thrombi were identified on follow-up study, and no patient had a clinical thromboembolic event between studies. CONCLUSIONS: These data strongly support the hypothesis that among patients with nonrheumatic atrial fibrillation, the mechanism of clinical benefit with 3 to 4 weeks of warfarin before cardioversion is related to thrombus resolution and prevention of new thrombus formation rather than thrombus organization.

Aged↗
PubMed1995

Life expectancy in the Marfan syndrome.

Data reported in 1972 indicated that lifespan in patients with the Marfan syndrome is markedly shortened, and that most deaths are cardiovascular. This study was performed to determine whether survival in the Marfan syndrome has changed since 1972, and to discern whether treatment (medical or surgical) has altered prognosis. Survival curves were generated on 417 patients from 4 referral centers, with a definite diagnosis of the Marfan syndrome. Birth date, age at death, cardiovascular surgery, or treatment with beta blockers, or any combination of these, were included in the analysis. Forty-seven of 417 patients died. Mean age at death (41 +/- 18 years) was significantly increased compared with age in 1972 (32 +/- 16 years, p = 0.0023). Median (50%) cumulative probability of survival in 1993 was 72 years compared with 48 years in 1972. Of 112 surgically treated patients, 10-year probability of survival was 70%. Patients undergoing surgery after 1980 enjoyed significantly increased survival than patients who had undergone operation before 1980 (p = 0.008). In conclusion, life expectancy for patients with the Marfan syndrome has increased > 25% since 1972. Reasons for this dramatic increase may include (1) an overall improvement in population life expectancy, (2) benefits arising from cardiovascular surgery, and (3) greater proportion of milder cases due to increased frequency of diagnosis. Medical therapy (including beta blockers) was also associated with an increase in probable survival.

Adult↗
PubMed1995

Transesophageal echocardiographically facilitated early cardioversion from atrial fibrillation using short-term anticoagulation: final results of a prospective 4.5-year study.

OBJECTIVES: We sought to validate the safety of transesophageal echocardiographically guided early cardioversion in conjunction with short-term anticoagulation as a strategy for guiding early cardioversion in hospitalized patients with atrial fibrillation. BACKGROUND: Because atrial thrombi are poorly seen by conventional imaging techniques, several weeks of prophylactic anticoagulation is routinely prescribed before cardioversion. Transesophageal echocardiography is a superior test for identifying atrial thrombi; preliminary feasibility studies have supported its use to guide early cardioversion for patients in whom no thrombus is observed, but safety has not been validated in any large series. METHODS: All patients admitted to hospital with atrial fibrillation during a 4.5-year period were screened. The inclusion criterion was a clinical duration of atrial fibrillation > 2 days or of unknown duration. Patients received anticoagulation with heparin/warfarin and underwent conventional transthoracic echocardiography followed by transesophageal study. Patients in whom transesophageal echocardiography revealed no atrial thrombus underwent pharmacologic or electrical cardioversion followed by warfarin therapy for 1 month. Cardioversion was deferred in patients with evidence of atrial thrombi, and they received prolonged warfarin treatment. RESULTS: Two hundred thirty-three patients (86% of those eligible) agreed to participate, and 230 underwent transesophageal echocardiography. Transesophageal echocardiography identified 40 atrial thrombi (left atrium 34, right atrium 6) in 34 patients (15%). One hundred eighty-six (95%) of 196 patients without thrombi had successful cardioversion to sinus rhythm, all without prolonged anticoagulation, and none (0%, 95% confidence interval 0% to 1.6%) experienced a clinical thromboembolic event. Eighteen patients with atrial thrombi underwent uneventful cardioversion after prolonged anticoagulation. CONCLUSIONS: Compared with smaller series that have shown only feasibility, this large prospective and consecutive study of patients undergoing transesophageal echocardiographically facilitated early cardioversion in conjunction with short-term anticoagulation validates the safety of this strategy. This treatment algorithm has a safety profile similar to conventional therapy and minimizes both the period of anticoagulation and the overall duration of atrial fibrillation.

Adult↗
PubMed1995

Controlled trial of fish oil for regression of human coronary atherosclerosis. HARP Research Group.

OBJECTIVES: This randomized clinical trial tested whether fish oil supplements can improve human coronary atherosclerosis. BACKGROUND: Epidemiologic studies of populations whose intake of oily fish is high, as well as laboratory studies of the effects of the polyunsaturated fatty acids in fish oil, support the hypothesis that fish oil is antiatherogenic. METHODS: Patients with angiographically documented coronary heart disease and normal plasma lipid levels were randomized to receive either fish oil capsules (n = 31), containing 6 g of n-3 fatty acids, or olive oil capsules (n = 28) for an average duration of 28 months. Coronary atherosclerosis on angiography was quantified by computer-assisted image analysis. RESULTS: Mean (+/- SD) baseline characteristics were age 62 +/- 7 years, plasma total cholesterol concentration 187 +/- 31 mg/dl (4.83 +/- 0.80 mmol/liter) and triglyceride levels 132 +/- 70 mg/dl (1.51 +/- 0.80 mmol/liter). Fish oil lowered triglyceride levels by 30% (p = 0.007) but had no significant effects on other plasma lipoprotein levels. At the end of the trial, eicosapentaenoic acid in adipose tissue samples was 0.91% in the fish oil group compared with 0.20% in the control group (p < 0.0001). At baseline, the minimal lumen diameter of coronary artery lesions (n = 305) was 1.64 +/- 0.76 mm, and percent narrowing was 48 +/- 14%. Mean minimal diameter of atherosclerotic coronary arteries decreased by 0.104 and 0.138 mm in the fish oil and control groups, respectively (p = 0.6 between groups), and percent stenosis increased by 2.4% and 2.6%, respectively (p = 0.8). Confidence intervals exclude improvement by fish oil treatment of > 0.17 mm, or > 2.6%. CONCLUSIONS: Fish oil treatment for 2 years does not promote major favorable changes in the diameter of atherosclerotic coronary arteries.

Adipose Tissue↗
PubMed1995

Family history of severe cardiovascular disease in Marfan syndrome is associated with increased aortic diameter and decreased survival.

OBJECTIVES: We attempted to determine whether a family history of severe cardiovascular disease in patients with the Marfan syndrome is associated with increased aortic dilation or decreased survival, or both. BACKGROUND: The prognostic importance of a family history of severe cardiovascular disease in patients with the Marfan syndrome has been incompletely examined. We hypothesized that such a family history would correlate with increased aortic dilation and would be associated with decreased survival. METHODS: One hundred eight affected patients and 48 unaffected family members from 33 multigenerational families with the Marfan syndrome underwent echocardiographic measurement of the aortic root, arch and mid-abdominal aorta. Date of birth and age at death ascertained from family pedigrees were used to perform life table analysis and estimate survival. RESULTS: Aortic root and arch diameters were significantly greater in patients with a family history of severe cardiovascular disease than in patients without such a family history. Of subjects in the highest quartile for aortic size, > 80% had such a family history in contrast to < 10% of those in the lowest quartile (chi-square 57.37, p < 0.00001). Mean age at death and cumulative probability of survival were significantly lower in patients with such a family history. CONCLUSIONS: Among patients with the Marfan syndrome, aortic dilation is greater and life expectancy shorter in those with a family history of severe cardiovascular manifestations. These data suggest that such a family history is an important risk factor for cardiovascular events in patients with the Marfan syndrome.

Adult↗
PubMed1994

Lack of association between cholesterol and coronary heart disease mortality and morbidity and all-cause mortality in persons older than 70 years.

OBJECTIVES: To determine whether elevated serum cholesterol level is associated with all-cause mortality, mortality from coronary heart disease, or hospitalization for acute myocardial infarction and unstable angina in persons older than 70 years. Also, to evaluate the association between low levels of high-density lipoprotein cholesterol (HDL-C) and elevated ratio of serum cholesterol to HDL-C with these outcomes. DESIGN: Prospective, community-based cohort study with yearly interviews. PARTICIPANTS: A total of 997 subjects who were interviewed in 1988 as part of the New Haven, Conn, cohort of the Established Population for the Epidemiologic Study of the Elderly (EPESE) and consented to have blood drawn. MAIN OUTCOME MEASURES: The risk factor-adjusted odds ratios of the 4-year incidence of all-cause mortality, mortality from coronary heart disease, and hospitalization for myocardial infarction or unstable angina were calculated for the following: subjects with total serum cholesterol levels greater than or equal to 6.20 mmol/L (> or = 240 mg/dL) compared with subjects with cholesterol levels less than 5.20 mmol/L (< 200 mg/dL); subjects in the lowest tertile of HDL-C level compared with those in the highest tertile; and subjects in the highest tertile of the ratio of total serum cholesterol to HDL-C level compared with those in the lowest tertile. RESULTS: Elevated total serum cholesterol level, low HDL-C, and high total serum cholesterol to HDL-C ratio were not associated with a significantly higher rate of all-cause mortality, coronary heart disease mortality, or hospitalization for myocardial infarction or unstable angina after adjustment for cardiovascular risk factors. The risk factor-adjusted odds ratio for all-cause mortality was 0.99 (95% confidence interval [CI], 0.56 to 2.69) for the group who had cholesterol levels greater than or equal to 6.20 mmol/L (> or = 240 mg/dL) compared with the group that had levels less than 5.20 mmol/L (< 200 mg/dL); 1.00 (95% CI, 0.59 to 1.70) for the group in the lowest tertile of HDL-C compared with those in the highest tertile; and 1.03 (95% CK, 0.62 to 1.71) for subjects in the highest tertile of the ratio of total serum cholesterol to HDL-C compared with those in the lowest tertile. CONCLUSIONS: Our findings do not support the hypothesis that hypercholesterolemia or low HDL-C are important risk factors for all-cause mortality, coronary heart disease mortality, or hospitalization for myocardial infarction or unstable angina in this cohort of persons older than 70 years.

Aged↗
PubMed1994

Impaired left atrial mechanical function after cardioversion: relation to the duration of atrial fibrillation.

OBJECTIVES: We hypothesized that the time course of the recovery of atrial systolic function may be related to the duration of atrial fibrillation before cardioversion and sought to study noninvasively the recovery of left atrial mechanical function utilizing serial transthoracic Doppler studies. BACKGROUND: Recovery of atrial mechanical function may be delayed for several weeks after successful cardioversion of atrial fibrillation to sinus rhythm. METHODS: After successful cardioversion, 60 patients with atrial fibrillation of brief (< or = 2 weeks, 17 patients), moderate (> 2 to 6 weeks, 22 patients) or prolonged (> 6 weeks, 21 patients) duration were followed up with serial transmitral pulsed Doppler echocardiography immediately (60 patients) and at 24 h (45 patients), 1 week (41 patients), 1 month (31 patients) and > 3 months (30 patients) after cardioversion. RESULTS: Atrial mechanical function is greater immediately and at 24 h and 1 week after cardioversion in patients with "brief" compared with "prolonged" atrial fibrillation. In all groups, atrial mechanical function increases over time, ultimately achieving similar levels. Full recovery of atrial mechanical function, however, is achieved within 24 h in patients with brief atrial fibrillation, within 1 week in patients with moderate-duration atrial fibrillation and within 1 month in patients with prolonged atrial fibrillation. CONCLUSIONS: Recovery of left atrial mechanical function is related to the duration of atrial fibrillation before cardioversion. These findings have important implications for assessing the early hemodynamic benefit of successful cardioversion.

Adult↗
PubMed1993

Cardioversion from atrial fibrillation without prolonged anticoagulation with use of transesophageal echocardiography to exclude the presence of atrial thrombi.

BACKGROUND: Because atrial thrombi are poorly detected by conventional noninvasive techniques such as transthoracic echocardiography, patients with prolonged atrial fibrillation usually receive several weeks of oral anticoagulation therapy before cardioversion is attempted. We wondered whether transesophageal echocardiography, an accurate method of detecting atrial thrombi, would allow early cardioversion to be performed safely if no thrombi were identified. METHODS: A total of 669 consecutive patients admitted with the diagnosis of atrial fibrillation were screened. Patients were excluded if they were receiving long-term anticoagulation, if the duration of atrial fibrillation was two days or less, if they were not candidates for cardioversion, or if transesophageal echocardiography was contraindicated. Of 119 qualifying patients, 94 agreed to participate; the average duration of atrial fibrillation was 4.5 weeks. Participating patients underwent transthoracic echocardiography and transesophageal echocardiography followed by cardioversion if no thrombi were seen. Short-term anticoagulation with heparin was used in 80 patients before cardioversion, and 60 patients received warfarin for one month after cardioversion. RESULTS: Fourteen atrial thrombi were identified in 12 patients (13 percent), and 12 of the 14 thrombi were visualized only on transesophageal echocardiography. Cardioversion was deferred in all 12 patients. Two of these 12 patients died suddenly; 4 of the 10 surviving patients underwent uneventful cardioversion after prolonged oral anticoagulation. Seventy-eight of the 82 patients without thrombi underwent successful cardioversion to sinus rhythm (47 by means of antiarrhythmic drugs and 31 by electrical cardioversion), all without long-term oral anticoagulation. None of these patients (95 percent confidence interval, 0 to 4.6 percent) had an embolic event. CONCLUSIONS: In patients with atrial fibrillation of unknown or prolonged duration who are not receiving long-term anticoagulation, atrial thrombi are detected by transesophageal echocardiography in only a small minority (13 percent in our study). Our preliminary data suggest that if transesophageal echocardiography excludes the presence of thrombi, early cardioversion can be performed safely without the need for prolonged oral anticoagulation before the procedure.

Adult↗
PubMed1993

High-density lipoprotein subfractions.

High-density lipoprotein (HDL) consists of a heterogeneous group of particles defined either by size or by apolipoprotein content. Subfractions of HDL appear to have distinct but interrelated metabolic functions, including facilitation of cholesteryl ester transfer to low- and very-low-density lipoproteins, modulation of triglyceride-rich particle catabolism, and, possibly, removal of cholesterol from peripheral tissues. Like HDL cholesterol, HDL subfractions are widely affected by a variety of factors. Subfractions also are markers for epidemiologic risk for coronary artery disease. Because they provide information about the physiologic processes of cholesterol metabolism, HDL subfractions are emerging as an increasingly important tool in the study of the relationship between lipids and cardiovascular disease.

Cholesterol↗
PubMed1993

Atrial ejection force: a noninvasive assessment of atrial systolic function.

OBJECTIVES: The purpose of this study was to define atrial ejection force and to develop a method for its noninvasive measurement from echocardiographic data. BACKGROUND: Assessment of diastolic function through measurement of the components of ventricular filling has largely neglected the vigor of atrial systole, in part because this has been difficult to quantify. However, atrial ejection force, defined as that force exerted by the left atrium to accelerate blood into the left ventricle during atrial systole, can be assessed noninvasively by combined two-dimensional imaging and Doppler echocardiography. This index of atrial function, based on classic newtonian mechanics, provides a physiologic assessment of atrial systolic function. METHODS: To evaluate the usefulness of atrial ejection force, we studied the return of left atrial ejection force in 29 patients after elective cardioversion for atrial fibrillation. Transmitral Doppler inflow patterns at rest were assessed immediately after cardioversion and at 24 h, 1 week, 1 month and > 3 months later. A healthy adult group (n = 10) served as control subjects. RESULTS: After successful cardioversion, atrial ejection force was significantly depressed compared with that in the control group (5.2 +/- 6.8 vs. 16.3 +/- 4.7 kdynes; p < 0.0001). Over successive weeks, atrial ejection force improved in the subgroup of patients who remained in sinus rhythm (n = 18), whereas no improvement was seen during the period of maintained sinus rhythm in the patients with subsequent reversion to atrial fibrillation (n = 11). CONCLUSIONS: Atrial ejection force provides a physiologic assessment of atrial systolic function and is a potentially useful index for assessing atrial contribution to diastolic performance. In patients who successfully underwent cardioversion from atrial fibrillation, atrial ejection force improved over several weeks only in the subgroup in which sinus rhythm was maintained.

Adult↗
PubMed1993

Efficacy of type 1C antiarrhythmic agents for treatment of resistant atrial fibrillation.

In order to determine the efficacy of type 1C agents (flecainide, encainide, propafenone) in patients with atrial fibrillation who have failed to maintain sinus rhythm with type 1A agents (quinidine, procainamide, disopyramide), 147 patients, that were admitted into the John Dempsey Hospital with new or recurrent atrial fibrillation between 1987-1991, were studied retrospectively. Out of the total, 29 patients converted spontaneously to sinus rhythm, 14 patients were left in atrial fibrillation, and 104 patients were given a type 1A antiarrhythmic. Sixty-five of these patients remained in sinus rhythm (54% converted on drug alone, 46% required electrical cardioversion) for at least 6 months. Of the remaining 39 patients, 28 were given a type 1C antiarrhythmic; 13 were successfully converted (61% chemical, 39% electrical) to and remained in sinus rhythm for at least 6 months; the remaining 15 either failed to convert or reverted to atrial fibrillation. New onset atrial fibrillation had a significantly lower incidence of congestive heart failure (10%) than recurrent atrial fibrillation (33%; P < 0.01). No differences in digoxin, beta blocker use, or other clinical characteristics were seen either between type 1A or type 1C successes or failures. Similarly, echocardiographic dimensions did not predict success or failure with either class of agent. In conclusion, type 1C antiarrhythmics for suppression of recurrent atrial fibrillation represent a reasonable therapeutic alternative for suppression of atrial fibrillation in patients who have failed type 1A agents. Prognostic factors predicting success or failure remain undetermined.

Aged↗
PubMed1991

Effects of serum lipid levels on restenosis after coronary angioplasty.

Although the association of serum lipid levels with the risk of atherosclerosis is well-recognized, the relation between these levels and restenosis after coronary angioplasty is uncertain. This study examines 186 patients enrolled in a trial of fish oil for prevention of restenosis. Fasting lipid levels (cholesterol, high density lipoprotein (HDL) cholesterol and triglycerides) were measured before angioplasty, and in 90 patients repeated at 6-month follow-up. Fifty-nine patients (32%) developed clinical restenosis confirmed by angiography. Patients who went on to develop restenosis underwent multivessel angioplasty (p less than 0.05) and were more likely to be on lipid-lowering therapy at baseline (27 vs 13%; p less than 0.05). In addition, they had higher baseline cholesterol/HDL ratios (6.5 +/- 2.2 vs 5.9 +/- 2.0; p less than 0.05) and triglyceride levels (233 +/- 210 vs 183 +/- 112 mg/dl; p less than 0.05). Multiple logistic regression analysis confirmed cholesterol/HDL ratios at baseline (p = 0.021) and follow-up (p = 0.0008) to be independent predictors of risk for restenosis. Using these data, regression lines have been developed that predict risk of restenosis based on type of procedure and on lipid values. These results suggest that serum lipid levels may be associated with the risk of clinical restenosis after coronary angioplasty.

Aged↗
PubMed1991

Comparison of the absorption and effect on platelet function of a single dose of n-3 fatty acids given as fish or fish oil.

To compare their relative absorption and effect on platelet function, concentrated fish oil and tuna were given to 10 subjects in a randomized crossover study. Although plasma enrichment of eicosapentaenoic acid (EPA) from either preparation was similar, relative absorption of EPA from tuna was significantly greater than that from fish oil (46.6 +/- 3.0 mg.L-1.g EPA-1 from tuna compared with 16 +/- 1.0 mg.L-1.g EPA-1 from fish oil, P less than 0.001). Relative absorption of docosahexaenoic acid (DHA) was equivalent (54.0 +/- 9.0 mg.L-1.g DHA-1 from tuna, 56 +/- 9.0 mg.L-1.g DHA-1 from fish oil, NS). Platelet aggregation in response to the endoperoxide analog U46619 was significantly diminished after either preparation but aggregation in response to other agonists, bleeding time, and membrane n-3 (omega-3) fatty acid content were not changed. Thus, n-3 fatty acids are well absorbed after one dose of either tuna or fish oil but EPA absorption appears to be more efficient from tuna. Additionally, a single dose of n-3 fatty acids decreases platelet aggregation by a mechanism not requiring incorporation into platelet membranes.

Absorption↗