PubMed Health⌕ Search

Biomedical subjects

A Maisel

Publications and source records attributed to A Maisel.

At least 19 recordsLinked to original sources
PubMed2003

Clinical applications of B-type natriuretic peptide (BNP) testing.

Many claims have been made in recent years regarding the utility of plasma B-type natriuretic peptide (BNP) concentration measurements in the diagnosis, risk stratification and monitoring of patients with heart failure. This paper summarizes the current evidence and provides guidance for practising clinicians. Overall, plasma BNP testing appears to be of most value in the diagnostic arena, where it is likely to improve the performance of non-specialist physicians in diagnosing heart failure. In clinical practice, BNP testing is best used as a 'rule out' test for suspected cases of new heart failure in breathless patients presenting to either the outpatient or emergency care settings; it is not a replacement for echocardiography and full cardiological assessment, which will be required for patients with an elevated BNP concentration. Although work is ongoing in establishing the 'normal' values of BNP, heart failure appears to be highly unlikely below a plasma concentration of 100 pg/ml. However, as BNP levels rise with age and are affected by gender, comorbidity and drug therapy, the plasma BNP measurement should not be used in isolation from the clinical context.

Ambulatory Care↗
PubMed2001

B-type natriuretic peptide in the diagnosis and management of congestive heart failure.

Finding a simple blood test that would aid in the diagnosis and management of patients with CHF clearly would have a favorable impact on the staggering costs associated with the disease. BNP, which is synthesized in the cardiac ventricles and correlates with LV pressure, amount of dyspnea, and the state of neurohormonal modulation, makes this peptide the first potential "white count" for heart failure. The fact that a point-of-care rapid assay for BNP has been approved by the FDA gives the clinician an opportunity to explore its potential usefulness. The author's data, and data from others, suggest that serial point-of-care testing of BNP will be of immense help in patients presenting to urgent care clinics with dyspnea. Additionally, BNP might serve as a screen for patients referred for echocardiography. A low BNP level makes echocardiographic indices of LV dysfunction (systolic and diastolic) highly unlikely. BNP also might be an effective way to improve the in-hospital management of patients admitted with decompensated CHF. In some instances, BNP levels may obviate the need for invasive hemodynamic monitoring and, in cases where such monitoring is used, may help tailor treatment of the decompensated patient. Finally, the role of BNP in the outpatient cardiac or primary care clinic may be one of critical importance in titration of therapies and in assessment of the state of neurohormonal compensation of the patient.

Atrial Natriuretic Factor↗
PubMed2001

A rapid bedside test for B-type peptide predicts treatment outcomes in patients admitted for decompensated heart failure: a pilot study.

OBJECTIVES: The goal of this study was to determine if B-type natriuretic peptide (BNP) levels predict outcomes of patients admitted with decompensated heart failure. BACKGROUND: Treatment of decompensated congestive heart failure (CHF) has often been based on titration of drugs to relieve patient's symptoms, a case that could be made for attempting to also treat neurohormonal abnormalities. Because BNP reflects both elevated left ventricular pressure as well as neurohormonal modulation, we hypothesized that BNP might be useful in assessing outcomes in patients admitted with decompensated CHF. METHODS: We followed 72 patients admitted with decompensated New York Heart Association class III to IV CHF, measuring daily BNP levels. We then determined the association between initial BNP measurement and the predischarge or premoribund BNP measurement and subsequent adverse outcomes (death and 30-day readmission). RESULTS: Of the 72 patients admitted with decompensated CHF, 22 end points occurred (death: n = 13, readmission: n = 9). In these patients, BNP levels increased during hospitalization (mean increase, 233 pg/ml, p < 0.001). In patients without end points, BNP decreased (mean decrease 215 pg/ml). Univariate analysis revealed that the last measured BNP was strongly associated with the combined end point. In patients surviving hospitalization, BNP discharge concentrations were strong predictors of subsequent readmission (area under the receiver operator curve of 0.73). CONCLUSIONS: In patients admitted with decompensated CHF, changes in BNP levels during treatment are strong predictors for mortality and early readmission. The results suggest that BNP levels might be used successfully to guide treatment of patients admitted for decompensated CHF.

Adult↗
PubMed2001

A rapid test for B-type natriuretic peptide correlates with falling wedge pressures in patients treated for decompensated heart failure: a pilot study.

OBJECTIVES: To determine if changes in B-type natriuretic peptide (BNP) levels can accurately reflect acute changes in pulmonary capillary wedge pressure during treatment of decompensated heart failure. BACKGROUND: Tailored therapy of decompensated congestive heart failure with hemodynamic monitoring is controversial. Other than the expense and complications of Swan-Ganz catheters, its use in titration of drug therapy has no conclusive end point. Because BNP reflects both elevated left ventricular pressure and neurohormonal modulation and has a short half-life, we hypothesized that levels of BNP would decline in association with falling wedge pressures. Final BNP levels would perhaps signify a new set point of neuromodulation. METHODS AND RESULTS: Twenty patients with decompensated New York Heart Association (NYHA) class III-IV congestive heart failure (CHF) undergoing tailored therapy were studied. BNP levels were drawn every 2 to 4 hours for the first 24 hours (active treatment phase) and then every 4 hours for the next 24 to 48 hours (stabilization period). Hemodynamic data was recorded simultaneously. In 15 patients whose wedge pressure responded to treatment in the first 24 hours, there was a significant drop in BNP levels (55%) versus nonresponders (8%). There was a significant correlation between percent change in wedge pressure from baseline per hour and the percent change of BNP from baseline per hour (r = 0.79, P <.05). When the wedge pressure was kept at a stable, low level during the stabilization phase, BNP levels continued to fall another 37% (937 +/- 140 pg/mL at 24 hours to 605 +/- 128 pg/mL). Patients who died (n = 4) had higher final BNP levels (1,078 +/- 123 pg/mL v 701 +/- 107 pg/mL). CONCLUSIONS: The data suggest that rapid testing of BNP may be an effective way to improve the in-hospital management of patients admitted with decompensated CHF. Although BNP levels will not obviate the need for invasive hemodynamic monitoring, it may be a useful adjunct in tailoring therapy to these patients.

Aged↗
PubMed2001

B-type natriuretic peptide levels: a potential novel "white count" for congestive heart failure.

Finding a simple blood test to aid in the diagnosis and treatment of patients with congestive heart failure could have a favorable impact on the costs associated with the disease. B-type natriuretic peptide (BNP) is synthesized in the cardiac ventricles, and its level correlates with left ventricular pressure, amount of dyspnea, and the state of neurohormonal modulation, thus making peptide the first potential "white count" for heart failure. Data indicate that serial point-of-care testing of BNP should be helpful in patients presenting to urgent care clinics with dyspnea. BNP may also serve as a screen for patients referred for echocardiography. A low BNP level makes left ventricular dysfunction (both systolic and diastolic) highly unlikely. BNP may also provide an effective means of improving in-hospital management of patients admitted with decompensated congestive heart failure. In some cases, BNP level observations may obviate the need for invasive hemodynamic monitoring and, when such monitoring is used, may help tailor treatment of the decompensated patient. Finally, the role of BNP in the outpatient cardiac or primary care clinic may be one of critical importance in titration of therapies as well as in assessing the state of neurohormonal compensation of the patient.

Atrial Natriuretic Factor↗
PubMed2001

B-type natriuretic peptide levels: diagnostic and therapeutic potential.

A blood test that would aid in the diagnosis and management of patients with congestive heart failure would have a favorable impact on the staggering costs of the disease. B-type naturetic peptide (BNP) is synthesized in the cardiac ventricles and its release is directly proportional to ventricular volume expansion and pressure overload. Levels of BNP correlate with left ventricular pressure, amount of dyspnea, and the state of neurohumoral modulation. BNP also correlates closely with New York Heart Association classification. A cut point of 100 pg/mL appears to discriminate patients with congestive heart failure from those without congestive heart failure. Measurement of BNP may also be an excellent screening tool for LV dysfunction. Key Words: Natriuretic peptides; neurohormonal; left-ventricular pressure;

Atrial Natriuretic Factor↗
PubMed1999

A comparison of troponin T and troponin I as predictors of cardiac events in patients undergoing chronic dialysis at a Veteran's Hospital: a pilot study.

OBJECTIVE: The purpose of this study was to prospectively evaluate the usefulness of the cardiac troponins as predictors of subsequent cardiac events in patients with chronic renal failure undergoing dialysis. BACKGROUND: Cardiac troponin T (cTnT) and I (cTnI) are cardiac markers that are specific for cardiac muscle. They are also excellent prognostic indicators for patients presenting with chest pain. Although cardiac disease is the leading cause of death in dialysis patients, standard methods to diagnose acute coronary syndromes in patients with renal failure are often misleading. METHODS: A six-month prospective study was done in a university-affiliated Veterans Hospital's dialysis clinic. Forty-nine patients undergoing chronic dialysis with no complaints of chest pain were followed for cardiac events occurring in the six months after cardiac troponin measurements. These included unstable angina, acute myocardial infarction and cardiac death. An additional 83 patients with renal failure but who were not undergoing dialysis were also examined. RESULTS: Within six months all three dialysis patients with elevated cTnI at entry into the study suffered an adverse complication (specificity and positive predictive value = 100%). Twenty-five patients had cTnT elevated at >0.10 ng/ml (53%). Patients with diabetes were more likely to have elevated troponin T levels (64% vs. 25%, p = 0.01). All six patients developing cardiac events within three months had elevations of cTnT >0.1 ng/ml (sensitivity = 100%). Whereas the specificity of cTnT was only 56% for a near-term cardiac event, the negative predictive value of cTnT using a cutoff of < or = 0.1 ng/ml was 100%. On restratifying patients using a cutoff value of cTnT of >0.2 ng/ml, only nine of 49 dialysis patients (18%) had elevated levels. In patients with renal failure not undergoing dialysis, only three of 83 (4%) had elevated troponin I or T. None of these patients suffered a cardiac event in the next six months. CONCLUSIONS: This prospective pilot study clearly delineates the troponins as important prognosticators in asymptomatic otherwise "stable" patients on chronic dialysis, especially those with concomitant diabetes mellitus. It also appears that troponins are more likely to be elevated in dialysis patients than other patients with renal failure not on dialysis. The above suggests that the combination of cTnI and cTnT might be very effective in elucidating cardiac risks of patients with renal failure undergoing chronic dialysis.

Angina, Unstable↗
PubMed1998

Experimental autoimmune myocarditis produced by adoptive transfer of splenocytes after myocardial infarction.

One possible mechanism for neurohumoral activation after myocardial infarction may be the generation of an immune response against cardiac self-antigens. We hypothesize that if there is a T cell-mediated reaction to self-antigens, the transfer of splenic lymphocytes from postinfarct rats into syngeneic rats with normal hearts should result in a T cell-mediated autoimmune myocarditis in the healthy syngeneic rats. Rats were killed 6 weeks after coronary ligation. Splenocytes from animals with large and small infarcts were purified from spleens, activated with concanavalin A, and injected in varying doses into normal syngeneic rats. These recipient rats were killed 6 weeks later, and histopathological studies were performed. Our results demonstrate in vivo evidence of lymphocyte-mediated myocardial injury by adoptive transfer of sensitized lymphocytes from rats who developed congestive heart failure after acute myocardial infarction. The amount of infiltrate and necrosis in the recipient rats appeared directly related to the size of the infarct from the donor rats. This suggests that larger infarcts lead to a greater inflammatory response as well as a greater propensity for alteration of cardiac surface antigens or the emergence of previously sequestered antigens. None of the other organs (kidney, liver, lung, or brain) had evidence of infiltrates. Two-dimensional echocardiography did not reveal systolic dysfunction. This study provides direct evidence of autoimmune myocardial injury produced by adoptive transfer of concanavalin A-activated splenocytes after myocardial infarction. We propose that neurohumoral activation early in the postinfarction period triggers a series of specific inflammatory and immunological events that lead to formation of specific clones of T cells. When these are activated and transferred into normal rats, cardiac-specific cellular infiltration occurs, occasionally accompanied by myocardial necrosis. This model should help to further explore the link between neurohumoral activation after myocardial infarction and the subsequent immune alterations that might be associated with the development and/or progression of congestive heart failure. Additionally, this might be a useful model in which to study other immune-mediated cardiomyopathies.

Adoptive Transfer↗
PubMed1998

Comparison between mixed venous oxygen saturation and thermodilution cardiac output in monitoring patients with severe heart failure treated with milrinone and dobutamine.

PURPOSE: Although thermodilution cardiac output (COtd) is the accepted method for monitoring patients with heart failure in the intensive care unit, it is particularly inaccurate in low-flow states and in the presence of tricuspid regurgitation; in addition, it does not adequately reflect the interaction between oxygen delivery and tissue oxygen extraction. We were concerned about the underuse of mixed venous oxygen saturation (SvO2) in this setting and hypothesized that it might be a more useful parameter than COtd for evaluating hemodynamic status and monitoring therapy in patients with severe congestive heart failure. PATIENTS AND METHODS: We determined the correlation coefficients between increasing dose of inotrope and each of the parameters COtd and SvO2 in 18 patients with congestive heart failure who received a 3-day trial of either milrinone or dobutamine during admission to the Veterans Affairs Medical Center in San Diego. In addition, we analyzed reproducibility of repeated COtd and SvO2 measurements taken at a single dose of inotrope. RESULTS: In patients receiving milrinone the increase in dose correlated much better with SvO2 (average correlation coefficient 0.79) than with COtd; this stronger correlation with SvO2 was seen in 82% of the trials reviewed (p < 0.05). In addition, we found that repeated SvO2 measurements taken at a single dose of milrinone were more reproducible than COtd as indicated by smaller relative 95% confidence intervals. In patients receiving dobutamine no significant trend in correlation coefficients or reproducibility was observed. CONCLUSION: The knowledge that there is a significant relation between SvO2 and increasing dose of milrinone therapy in patients with severe heart failure and tricuspid regurgitation has practical value for physicians monitoring these patients in the intensive care unit. We believe this study demonstrates the worth of SvO2 in detecting hemodynamic change during trials of milrinone therapy and that this parameter may in fact be more reproducible than traditional thermodilution methods.

Aged↗
PubMed1998

Beneficial effects of intermittent home administration of the inotrope/vasodilator milrinone in patients with end-stage congestive heart failure: a preliminary study.

BACKGROUND: End-stage congestive heart failure (CHF) is associated with a high mortality rate and is often refractory to standard medical treatment. Although parenteral inotropes have been beneficial in hospitalized patients, their use in outpatients has been limited by toxicity and tachyphylaxis. METHODS AND RESULTS: To determine whether patients with end-stage CHF could safely tolerate intermittent outpatient inotropic therapy and demonstrate both symptomatic and functional improvement with these agents, we studied the effects of low-dose, intermittent home infusions of the inotrope/vasodilator milrinone in 10 patients with end-stage CHF. After showing hemodynamic improvement with milrinone while hospitalized, central lines were placed and patients were given the drug at home with small portable infusion pumps, starting at 3 days a week for 6 hours at a time over a 3-month period. Patients tolerated the drug well, with no deaths and a fourfold decrease in hospitalizations during the study. Arrhythmias were minimal and angina decreased in two patients. Mean total, physical, and emotional scores on the Minnesota Living with Heart Failure Questionnaire reflected a general trend of symptomatic improvement throughout the infusion period. The mean number of reported hours of improvement after infusion progressively increased throughout the study, producing a mean of 25 hours of postinfusion improvement during the final week (p < 0.01). Repeat hemodynamic study at the end of the 3-month period showed trends toward improvement in cardiac function. CONCLUSIONS: This is the first study to demonstrate safety, efficacy, hemodynamic, and functional improvement in patients receiving low-dose, intermittent outpatient milrinone therapy. We believe this improvement partly relates to a "training" effect on the heart or peripheral muscles and circulation. These promising results suggest that given appropriately, inotropes have an important therapeutic role in the outpatient treatment of end-stage CHF.

Adult↗
PubMed1991

Trends in use of coronary angiography in subacute phase of myocardial infarction.

BACKGROUND: Most patients do not undergo acute reperfusion after myocardial infarction, and which of these patients should undergo coronary angiography is still debated. METHODS AND RESULTS: We analyzed the 1-year clinical outcomes and rates of coronary angiography performed as late as 60 days after myocardial infarction in 3,804 patients admitted between 1979 and 1988 and followed in six different centers. Patients less than 75 years old were classified into low-, medium-, and high-risk groups using a multivariate analysis of historical and clinical variables gathered during the first 8 hospital days. Patients who underwent early reperfusion (17%, all after 1984) were analyzed separately. To analyze time trends, patients were compared before and after mid-1984. Mortalities from day 9 through 1 year were similar for the two time periods in the low- (3.3% versus 2.5%) and medium-risk (7.4% versus 5.6%) groups, but mortality was lower for the high-risk group after 1984 (31.6% versus 20.0%). The proportion of patients undergoing coronary angiography increased dramatically in each group after 1984 (low risk, 18% versus 48%; medium risk, 23% versus 49%; high risk, 10% versus 32%, before and after 1984, respectively). Furthermore, a large percentage of patients (more than 40%) in the low-risk group did not have at least one of the indications for coronary angiography recently recommended by a joint task force. Among patients undergoing coronary angiography, the proportion of patients with three-vessel coronary artery disease decreased after 1984, whereas the proportion undergoing mechanical revascularization in the year after infarction increased in all risk groups. CONCLUSIONS: Despite the recent development of noninvasive techniques with high sensitivity for detecting high-risk patients after myocardial infarction, coronary angiography is being performed increasingly in all patients, including those determined to be at low risk for complications based on clinical data. The economic consequences of such a trend could be considerable, and its impact requires careful analysis.

Age Factors↗
PubMed1990

Decreased adrenergic sensitivity in patients with hypothyroidism.

Cardiovascular sensitivity to catecholamines was assessed in 15 patients with hypothyroidism (mean [+/- SEM] thyroxine [T4] index 2.7 +/- 0.5 micrograms/100 ml, thyroid stimulating hormone [TSH] 136.9 +/- 48.3 microU/ml), aged 45 +/- 4 years and in 8 healthy control subjects. The study was repeated in 10 patients with hypothyroidism 4.0 +/- 0.5 months after thyroid replacement therapy (T4 index 9.9 +/- 2.1 micrograms/100 ml, TSH 3.5 +/- 1.3 microU/ml). In addition, basal, average and maximal heart rates were measured using 24 h ambulatory electrocardiographic (ECG) monitoring, and plasma levels of epinephrine and norepinephrine were determined before and after thyroid replacement. Heart rate increased less after bolus injection of 0.8, 1.6 and 3.2 micrograms of isoproterenol in the hypothyroid (10 +/- 2, 15 +/- 2 and 21 +/- 4 beats/min, respectively) than in the euthyroid (16 +/- 3, 22 +/- 3 and 30 +/- 4 beats/min, respectively) state (p less than 0.05). Control subjects reacted similarly to patients receiving thyroid replacement. Basal heart rate (64 +/- 3 versus 68 +/- 3 beats/min, p less than 0.05) and maximal heart rate (116 +/- 5 versus 133 +/- 5 beats/min, p less than 0.05) were lower on 24 h ambulatory ECG monitoring in the hypothyroid than euthyroid state despite higher basal plasma norepinephrine levels (394 +/- 45 versus 315 +/- 45 pg/ml, p less than 0.05). Thus, patients with hypothyroidism display a decreased cardiac chronotropic response to beta-adrenergic stimulation. This may contribute in part to the decreased basal and maximal daily heart rates seen in patients with hypothyroidism, which occurs despite elevated plasma norepinephrine levels.

Adrenergic beta-Agonists↗
PubMed1989

Role of guanine nucleotide regulatory proteins in insulin stimulation of glucose transport in rat adipocytes. Influence of bacterial toxins.

The potential role of guanine nucleotide regulatory proteins (G-proteins) in acute insulin regulation of glucose transport was investigated by using bacterial toxins which are known to modify these proteins. Cholera-toxin treatment of isolated rat adipocytes had no effect on either 2-deoxyglucose transport or insulin binding. Pertussis-toxin treatment resulted in an inhibition of both insulin binding and glucose transport. Insulin binding was decreased in pertussis-toxin-treated cells by up to 40%, owing to a lowering of the affinity of the receptor for hormone, with no change in hormone internalization. The dose-response curve for insulin stimulation of glucose transport was strongly shifted to the right by pertussis-toxin treatment [EC50 (half-maximally effective insulin concn.) = 0.31 +/- 0.04 ng/ml in control cells; 2.29 +/- 1.0 in treated cells), whereas cholera toxin had only a small effect (EC50 = 0.47 +/- 0.02 ng/ml). Correcting for the change in hormone binding, pertussis toxin was found to decrease the coupling efficiency of occupied receptors (50% of maximal insulin effect with 928 molecules bound/cell in control and 3418 in treated cells). Pertussis-toxin inhibition of insulin sensitivity was slow in onset, requiring 2-3 h for completion. Under conditions where pertussis-toxin inhibition of insulin sensitivity was maximal, a 41,000 Da protein similar to the alpha subunit of Gi (the inhibitory G-protein) was found to be fully ribosylated. These results are consistent with the concept that pertussis-toxin-sensitive G-protein(s) can modify the insulin-receptor/glucose-transport coupling system.

Adenosine Deaminase↗
PubMed1989

Central nervous system side effects of beta-adrenergic blocking agents with high and low lipid solubility.

beta-adrenergic blocking agents have undesirable effects believed to be mediated through the central nervous system (CNS). If these effects are due to direct CNS action, less lipid soluble agents ought to have fewer effects. Accordingly, several formal psychological tests of items such as mood, motivation, and anxiety were used in a double-blinded crossover study in 17 hypertensive subjects taking equipotent beta blocking agents with high (propranolol) and low (atenolol) lipid solubility. Patients had less negative effects (p less than 0.05) on 12 of 21 items evaluated with atenolol compared to propranolol while peripheral beta blockade [beta 1, exercise heart rate (HR), and blood pressure (BP)] was equivalent. These results suggest that the mental changes which accompany beta blockade therapy are mediated directly in the CNS and that less soluble drugs can be expected to have fewer CNS effects.

Adult↗
PubMed1983

Continuous electrocardiographic monitoring in patients with sickle-cell anemia during pain crisis.

Electrocardiographic studies in patients with sickle-cell anemia have been performed during the normal resting state with routine twelve-lead ECGs. We studied 30 patients with sickle-cell disease in acute crisis with 24-hour continuous electrocardiographic monitoring. The standard ECG demonstrated a high incidence of abnormalities, but only three patients had arrhythmias. These findings contrasted sharply with the results of continuous monitoring, during which arrhythmias were detected in 24 of 30 patients. They were fairly evenly split between atrial (60%) and ventricular (67%). Nine of the patients had "complex arrhythmias" including two with episodes of ventricular tachycardia. Seventeen patients subsequently underwent equilibrium gated-blood pool scans. Eight patients had abnormal contractility and tended to have more arrhythmias on monitoring than those with normal contractility. Thus, continuous electrocardiographic monitoring of sickle-cell patients during crisis revealed a higher incidence of arrhythmias than previously thought.

Adolescent↗