PubMed Health⌕ Search

Biomedical subjects

A D Michaels

Publications and source records attributed to A D Michaels.

17 recordsLinked to original sources
PubMed2001

Use of a percutaneous arterial suture device (Perclose) in patients undergoing percutaneous balloon aortic valvuloplasty.

Percutaneous balloon aortic valvuloplasty has been used as a therapeutic option for patients with severe aortic stenosis who are not candidates for aortic valve replacement. This procedure has been limited by both the high rate of aortic valve restenosis and high procedural morbidity related chiefly to the large femoral arteriotomies required. The purpose of this study was to assess the feasibility and vascular complication rate using the "Preclose" technique in patients undergoing balloon aortic valvuloplasty. We evaluated the immediate and 30-day results in 18 consecutive patients undergoing this procedure. Angiographically significant peripheral vascular disease was present in 39% of cases. Aortic balloon dilation produced significant decreases in the mean aortic valve pressure gradient from 55 +/- 20 mmHg to 30 +/- 22 mmHg (P < 0.001). Closure of the arteriotomy with an 8F (10F in 1 case) Perclose device led to immediate hemostasis in all patients. Perclose of the contralateral femoral arterial site with a 6F device was attempted in 50%, all of which were successful. The mean length of bed rest was 4.5 +/- 0.9 hr. No procedural was observed. No patient had a local vascular complication, and no patient required blood product transfusion after the procedure. The use of the "Preclose" technique for closure of femoral arteriotomies after balloon aortic valvuloplasty is feasible and associated with a low rate of periprocedural and short-term vascular complications.

Adult↗
PubMed2001

Does higher diastolic augmentation predict clinical benefit from enhanced external counterpulsation?: Data from the International EECP Patient Registry (IEPR).

BACKGROUND: Enhanced external counterpulsation (EECP) has been demonstrated to be an effective treatment for stable angina in patients with coronary disease. The hemodynamic effects of EECP are maximized when the ratio of diastolic to systolic pressure area is in the range of 1.5 to 2.0. HYPOTHESIS: It is hypothesized that patients undergoing EECP who are able to achieve higher diastolic augmentation (DA) ratios may derive greater clinical benefit. This study examines the relationship between the DA ratio and clinical outcomes in patients undergoing EECP. METHODS: We analyzed demographic, noninvasive hemodynamic, and clinical outcome data on 1,004 patients enrolled in the International EECP Patient Registry (IEPR) for treatment of chronic angina between January 1998 and August 1999. Blood pressure waveforms were recorded from finger plethysmography. Six-month clinical outcomes were obtained by telephone interview. RESULTS: At the end of EECP treatment, 370 (37%) patients had a higher DA ratio (defined as > or = 1.5) and 634 (63%) had a lower DA ratio (defined as < 1.5). Factors associated with a lower DA ratio included age > or =65 years (p <0.001), female gender (p < 0.001), left ventricular ejection fraction < 35% (p < 0.05), hypertension (p < 0.01), prior coronary bypass surgery (p < 0.01), noncardiac vascular disease (p < 0.001), multivessel disease (p < 0.01), congestive heart failure (p < 0.01), current smoking (p < 0.01), unsuitability for further revascularization (p < 0.001), and higher baseline angina class (p < 0.001). There were no significant differences regarding diabetes mellitus, prior coronary angioplasty, prior myocardial infarction, or antianginal medication use between patients with higher or lower DA ratios. Based on a multiple logistic regression model, independent predictors of a DA ratio < 1.5 at the end of EECP included current smoking (odds ratio 3.3; 95% confidence intervals 2.0-5.4); multivessel disease (1.7; 1.3-2.3); female gender (2.2; 1.7-3.0); no prior EECP (1.9; 1.1-3.3); noncardiac vascular disease (2.3; 1.7-2.9); age > or = 65 years (1.7; 1.4-2.2), and patients not suitable for revascularization (1.6; 1.2-2.0). By the end of therapy, there were no significant differences in myocardial infarction, revascularization rates, or nitroglycerin use with respect to higher DA ratios. At 6-month follow-up, patients with higher DA had a trend toward a greater reduction in angina class compared with those with lower DA (p = 0.069). There was a significantly higher rate of unstable angina and congestive heart failure in the group not achieving higher augmentation (p < 0.05). CONCLUSIONS: Patients who are younger, male, nonsmoking, and without multivessel coronary or noncardiac vascular disease are most likely to have higher DA with EECP. Patients with higher DA tended to have a greater reduction in angina class at 6-month follow-up compared with those with lower DA ratios. There is evidence that higher DA ratios are associated with improved short- or long-term clinical outcomes, suggesting that clinical benefit from EECP is associated with the magnitude of DA.

Aged↗
PubMed2000

Microvascular dysfunction in acute myocardial infarction: focus on the roles of platelet and inflammatory mediators in the no-reflow phenomenon.

Recent interest has shifted from infarct artery patency to microvascular perfusion in the evaluation of patients with acute myocardial infarction (AMI). Microvascular dysfunction occurs in a substantial proportion of patients, despite aggressive therapy with thrombolytic agents and/or percutaneous mechanical revascularization techniques. Patients with impaired microvascular perfusion after immediate reperfusion therapy have an adverse clinical prognosis. Recent studies have extended our understanding of the pathophysiology of this so-called no-reflow phenomenon, focusing on the critical roles of platelet and inflammatory mediators leading to microvascular obstruction and reperfusion injury. Moving beyond the Thrombolysis in Myocardial Infarction (TIMI) flow grade system, new techniques have been developed to assess microvascular perfusion, including TIMI frame counting, angiographic myocardial perfusion grading, myocardial contrast echocardiography, Doppler flow wire studies, nuclear scintigraphy, and magnetic resonance imaging. Armed with a greater understanding of the primary mediators of microvascular dysfunction, these tools may identify improved therapy directed at optimizing myocardial perfusion in patients with AMI.

Capillary Permeability↗
PubMed2000

Effects of the repeated administration of adenosine and heparin on myocardial perfusion in patients with chronic stable angina pectoris.

The mechanism by which ischemia stimulates angiogenesis is unknown. Adenosine is released during myocardial ischemia and may be a mediator of this process. Experimental data suggest that heparin may enhance this effect. The purpose of this open-labeled, placebo-controlled trial was to determine whether repeated intravenous administration of adenosine and heparin could mimic physiologic angiogenesis and reduce the amount of exercise-induced myocardial ischemia in patients with coronary artery disease. Subjects with chronic stable angina refractory to conventional medical therapy and not suitable for revascularization received either adenosine (140 microg/kg/min for 6 minutes) and heparin (10,000 U bolus), (n = 14), or placebo, (n = 7) daily for 10 days. All patients underwent baseline and follow-up exercise testing with thallium-201 single-photon emission computed tomography myocardial perfusion imaging. A semiquantitative assessment of the extent and severity of the perfusion abnormalities was calculated by 2 blinded investigators. There was no significant change in exercise duration or in the peak heart rate systolic blood pressure product associated with adenosine and heparin compared with placebo treatment. There was, however, a 9% reduction in the extent (60.6 +/- 4.0 vs 54.9 +/- 4.1, p = 0.03) and a 14% improvement in severity (41.5 +/- 3.2 vs 35.7 +/- 2.9, p = 0.01) of the myocardial perfusion abnormalities seen in patients who received adenosine and heparin compared with placebo. Thus, in this pilot study, repeated administration of adenosine and heparin reduced the amount of exercise-induced ischemia in patients with chronic stable angina refractory to conventional treatment.

Adenosine↗
PubMed2000

Intracoronary measurement of pulsus alternans.

Pulsus alternans is typically found in patients with left ventricular systolic dysfunction. We describe a woman with biventricular systolic dysfunction and pulsus alternans in the right ventricle, pulmonary artery, and aorta. Coronary angiography revealed an intermediate stenosis in the proximal left anterior descending (LAD) coronary artery. Pulsus alternans was demonstrated in the mid LAD using a 0.014" guidewire-mounted pressure sensor. An abnormal fractional flow reserve was measured in the LAD. Cathet. Cardiovasc. Intervent. 51:335-338, 2000.

Aged↗
PubMed1999

Early use of ACE inhibitors in the treatment of acute myocardial infarction in the United States: experience from the National Registry of Myocardial Infarction 2. National Registry of Myocardial Infarction 2 participants.

This study was undertaken to examine recent trends in the use of angiotensin-converting enzyme (ACE) inhibitors within 24 hours of admission in patients hospitalized for acute myocardial infarction (AMI) and to identify clinical factors associated with ACE inhibitor-prescribing patterns. Demographic, procedural, and acute medication use from 202,438 patients with AMI were collected at 1,470 US hospitals participating in the National Registry of Myocardial Infarction 2 from June 1994 through June 1996. Acute ACE inhibitor use increased from 14.0% in 1994 to 17.3% in 1996. After controlling for all important clinical variables, we found that there was a significant increase in the odds of acute ACE inhibitor treatment over time (odds ratio [OR]1.07 for each 180-day period; 95% confidence intervals [CI] 1.06 to 1.08; p<0.0001). Univariate data suggested that patients treated acutely with ACE inhibitors tended to be older (70.9 vs. 67.2 years) and had lower rates of in-hospital mortality (8.8% vs. 11.0%). Independent predictors of receiving an ACE inhibitor acutely included anterior wall infarction (OR 1.36; 95% CI 1.32 to 1.40), Killip class 2 or 3 (OR 1.77; 95% CI 1.72 to 1.83), prior myocardial infarction (OR 1.33; 95% CI 1.30 to 1.37), prior history of congestive heart failure (OR 1.88; 95% CI 1.82 to 1.95), and diabetes mellitus (OR 1.34; 95% CI 1.30 to 1.38). Physicians are prescribing ACE inhibitors acutely in patients with AMI with increasing frequency. Patients with evidence of congestive heart failure and those with anterior myocardial infarction have the greatest expected benefit from such therapy, and these persons receive such treatment most often. However, most patients hospitalized with AMI do not receive this potentially life-saving therapy.

Aged↗
PubMed1998

Multivessel coronary thrombosis treated with abciximab (ReoPro) in a patient with essential thrombocythemia.

A 50-year-old man was admitted with acute inferior and anterior myocardial infarction. The patient was diagnosed with essential thrombocythemia (ET) based on the findings of marked thrombocytosis of 1,113 x 10(3)/mm3, splenomegaly, and numerous clumping megakaryocytes on bone marrow biopsy. Emergent coronary angiography revealed extensive multivessel thrombosis involving the left main coronary artery and completely occluding the proximal right coronary artery. In addition to standard therapy with aspirin, heparin, and primary angioplasty of the right coronary artery, the patient received additional antiplatelet therapy with ticlopidine, hydroxyurea, and the platelet glycoprotein IIb/IIIa receptor-inhibiting monoclonal antibody drug abciximab (ReoPro). Serial coronary angiograms 1 and 5 days following the infarction showed progressive thrombus resolution. The pathophysiologic mechanisms and therapeutic challenges of ET-associated coronary thrombosis are discussed in this report.

Abciximab↗
PubMed1998

Use of angiotensin-converting enzyme inhibitors at discharge in patients with acute myocardial infarction in the United States: data from the National Registry of Myocardial Infarction 2.

OBJECTIVES: This study was undertaken to examine recent trends in the use of angiotensin-converting enzyme (ACE) inhibitor therapy in patients discharged after acute myocardial infarction (AMI) and to identify clinical factors associated with ACE inhibitor prescribing patterns. BACKGROUND: Clinical trials have demonstrated a significant mortality benefit in patients treated with ACE inhibitors after AMI. Numerous studies have demonstrated underuse of other beneficial treatments for patients with AMI, such as beta-adrenergic blocking agents, aspirin and immediate reperfusion therapy. METHODS: Demographic, procedural and discharge medication data from 190,015 patients with AMI were collected at 1,470 U.S. hospitals participating in the National Registry of Myocardial Infarction 2. RESULTS: Prescriptions for ACE inhibitor therapy at hospital discharge increased from 25.0% in 1994 to 30.7% in 1996. Patients with a left ventricular ejection fraction < or =40% or evidence of congestive heart failure while in the hospital were discharged with ACE inhibitor treatment 42.6% of the time. Of patients experiencing an anterior wall myocardial infarction and no evidence of heart failure, 26.1% of patients were discharged with this treatment. Of the remaining patients, 15.6% received ACE inhibitors at discharge. ACE inhibitors were prescribed more often to elderly and diabetic patients as well as those requiring intraaortic balloon pump placement. This therapy was given less often to patients who underwent revascularization with coronary angioplasty or coronary artery bypass graft surgery or were treated with calcium channel blocking agents. CONCLUSIONS: Physicians are prescribing ACE inhibitors in patients with myocardial infarction with increasing frequency. Those patients with the greatest expected benefit receive ACE inhibitor treatment most often. However, the majority of even these high risk patients were not discharged with this life-saving therapy.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Risk stratification after acute myocardial infarction in the reperfusion era.

Historically, risk stratification for survivors of acute myocardial infarction (AMI) has centered on 3 principles: assessment of left ventricular function, detection of residual myocardial ischemia, and estimation of the risk for sudden cardiac death. Although these factors still have important prognostic implications for these patients, our ability to predict adverse cardiac events has significantly improved over the last several years. Recent studies have identified powerful predictors of adverse cardiac events available from the patient history, physical examination, initial electrocardiogram, and blood testing early in the evaluation of patients with AMI. Numerous studies performed in patients receiving early reperfusion therapy with either thrombolysis or primary angioplasty have emphasized the importance of a patent infarct related artery for long-term survival. The predictive value of a variety of noninvasive and invasive tests to predict myocardial electrical instability have been under active investigation in patients receiving early reperfusion therapy. The current understanding of the clinically important predictors of clinical outcomes in survivors of AMI is reviewed in this article.

Death, Sudden, Cardiac↗