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Biomedical subjects

A Halkin

Publications and source records attributed to A Halkin.

16 recordsLinked to original sources
PubMed2004

Late incomplete lesion coverage following Cypher stent deployment for diffuse right coronary artery stenosis.

The availability of the only drug eluting stent currently approved in the USA has been limited, so that operators often resort to the deployment of multiple undersized stents and post-stenting high pressure inflations with larger balloons to achieve optimal lesion coverage and stent expansion. A case of stent fracture following percutaneous coronary intervention in which this strategy was used is reported.

Angioplasty, Balloon, Coronary↗
PubMed2001

Pause-dependent torsade de pointes following acute myocardial infarction: a variant of the acquired long QT syndrome.

OBJECTIVES: We report on a previously unrecognized form of the long QT syndrome (QT interval prolongation and pause-dependent polymorphic ventricular tachycardia [VT]) entirely related to myocardial infarction (MI). BACKGROUND: Polymorphic VT in the setting of acute MI generally occurs during the hyperacute phase, is related to ischemia, and is not associated with QT prolongation. Although QT prolongation after MI is well described, typical pause-dependent polymorphic VT (torsade de pointes) secondary to uncomplicated MI was previously unknown. METHODS: Of 434 consecutive admissions for acute MI, 8 patients had progressive QT prolongation that led to typical torsade de pointes. None of these patients had active ischemia or other known causes of QT prolongation. These patients were compared with 100 consecutive patients with uncomplicated MI who served as controls. RESULTS: The incidence of torsade de pointes following MI was 1.8% (95% confidence interval 0.8% to 3.6%). The QTc intervals of patients and controls were similar on admission. The QTc lengthened by day 2 in both groups, but more so in patients with torsade de pointes (from 470 +/- 46 to 492 +/- 57 ms [p < 0.05] and from 445 +/- 58 to 558 +/- 84 ms, respectively [p < 0.01]). Maximal QT prolongation and torsade de pointes occurred 3 to 11 days after infarction. Therapy included defibrillation, magnesium, lidocaine and beta-blockers. Three patients required rapid cardiac pacing. The long-term course was uneventful. CONCLUSIONS: Infarct-related torsade de pointes is uncommon but potentially lethal. An acquired long QT syndrome should be considered in patients recovering from MI who experience polymorphic VT as specific therapeutic measures are mandatory.

Aged↗
PubMed2001

Sulfonylureas are not associated with increased mortality in diabetics treated with thrombolysis for acute myocardial infarction.

BACKGROUND: Sulfonylurea compounds may impair ischemic preconditioning and endogenous fibrinolysis. Increased mortality has been reported in diabetics receiving these drugs prior to admission for acute myocardial infarction when treated by direct angioplasty. Although thrombolytics are currently employed far more frequently than direct angioplasty the effect of sulfonylureas on mortality in the setting of thrombolysis has not been previously addressed. METHODS: Two hundred forty five diabetics treated with either accelerated t-PA or streptokinase in a national, multi-center, randomized comparison of argatroban vs. heparin (n=1200) were grouped by anti-diabetic treatment prior to hospitalization, and their outcomes were compared by retrospective analysis. RESULTS: Baseline characteristics were similar in all groups (sulfonylureas: n=121, oral medications other than sulfonylureas: n=17, insulin: n=28, diet alone: n=79). Sulfonylurea use was not associated with increased mortality or adverse event rates. By logistic regression analysis with diet treatment as reference, only prior insulin use was associated with higher risk for mortality at 30 days and 1 year (odds ratios 4.5 and 5.22, respectively, p<0.05). CONCLUSIONS: Sulfonylureas use prior to admission is not associated with adverse outcomes in diabetics treated with thrombolytics for myocardial infarction. Since direct angioplasty may increase mortality in patients taking these drugs, a randomized trial is needed to specifically compare different strategies of acute reperfusion in diabetics.Abbreviated abstract. Increased mortality has been reported in diabetics using sulfonylureas when treated for myocardial infarction by direct angioplasty. No study has specifically addressed the effect of these drugs on outcomes in the setting of thrombolysis. In a retrospective analysis of 245 diabetics treated with thrombolysis in a randomized comparison of argatroban vs. heparin, outcomes were compared in relation to anti-diabetic therapy prior to admission. Sulfonylurea use did not adversely affect prognosis, which was worst among diabetics previously treated with insulin. In conclusion, sulfonylureas do not worsen outcomes of diabetics treated with current thrombolytic regimens in comparison with other anti-diabetic treatments.

Aged↗
PubMed2001

Catheter-delivered ultrasound therapy for native coronary arterial thrombosis and occluded saphenous vein grafts.

Acute coronary thrombosis, overlying ruptured atherosclerotic plaque, is the hallmark of myocardial infarction and unstable angina. Despite use of modern therapeutic modalities, including glycoprotein IIb/IIIa antagonists and stenting, intracoronary thrombus heralds an increased risk of serious complications following percutaneous coronary interventions (PCI). Abundant in vitro and in vivo experimental data have proven that ultrasound energy is capable of lysing intravascular thrombus without injuring the vessel wall. Expanding experience and technological advancements now allow us to use this tool in clinical practice. In this article we review the emergence of percutaneous ultrasonic thrombolysis as a safe and effective tool for treatment of patients in various clinical settings associated with coronary thrombosis.

Animals↗
PubMed2000

Pancreatic and duodenal homeobox gene 1 induces expression of insulin genes in liver and ameliorates streptozotocin-induced hyperglycemia.

Insulin gene expression is restricted to islet beta cells of the mammalian pancreas through specific control mechanisms mediated in part by specific transcription factors. The protein encoded by the pancreatic and duodenal homeobox gene 1 (PDX-1) is central in regulating pancreatic development and islet cell function. PDX-1 regulates insulin gene expression and is involved in islet cell-specific expression of various genes. Involvement of PDX-1 in islet-cell differentiation and function has been demonstrated mainly by 'loss-of-function' studies. We used a 'gain-of-function' approach to test whether PDX-1 could endow a non-islet tissue with pancreatic beta-cell characteristics in vivo. Recombinant-adenovirus-mediated gene transfer of PDX-1 to the livers of BALB/C and C57BL/6 mice activated expression of the endogenous, otherwise silent, genes for mouse insulin 1 and 2 and prohormone convertase 1/3 (PC 1/3). Expression of PDX-1 resulted in a substantial increase in hepatic immunoreactive insulin content and an increase of 300% in plasma immunoreactive insulin levels, compared with that in mice treated with control adenovirus. Hepatic immunoreactive insulin induced by PDX-1 was processed to mature mouse insulin 1 and 2 and was biologically active; it ameliorated hyperglycemia in diabetic mice treated with streptozotocin. These data indicate the capacity of PDX-1 to reprogram extrapancreatic tissue towards a beta-cell phenotype, may provide a valuable approach for generating 'self' surrogate beta cells, suitable for replacing impaired islet-cell function in diabetics.

Adenoviridae↗
PubMed1999

[Severe heat stroke in an intensive care unit: course of the disease in the intensive care unit, and early and subsequent treatment results].

During the August 1998 heat wave in Tel Aviv we admitted many patients for acute heat-related illness; 6 had severe heat stroke and were admitted in critical condition. We describe their clinical courses during the first 5 days of hospitalization, including response to treatment and implications for future management of this disorder. The mean APACHE II score of the 6 was 30 +/- 3.5 and mean Glasgow Coma Scale rating 3.5 +/- 0.5; they were in hypovolemic shock and respiratory failure, necessitating mechanical ventilation. Despite early effective therapy (core temperature in all was reduced to less than 39 degrees C in less than 1 hour), there was 1 death (mortality 15%) and 4 required further intensive care for life-threatening multiple organ failure. During severe heat waves a significant number of referrals for acute heat-related illness must be anticipated, possibly overwhelming admission capacity of regional intensive-care units. Severe heat stroke complicated by multi-organ failure is not necessarily related to prior physical activity. Although important in determining prognosis, early treatment does not prevent severe complications. Mechanisms regulating body heat may remain disturbed for days following early treatment and apparent stabilization, mandating continued hospitalization.

APACHE↗
PubMed1998

Routine Coronary Arteriography Following Thrombolytic Therapy for Acute Myocardial Infarction: An Unsettled Controversy.

Although coronary artery disease remains the leading cause of death in industrialized countries, the management of patients recovering from acute myocardial infarction varies significantly. The issue of routine arteriography and revascularization following thrombolytic therapy remains controversial despite substantial evidence associating infarct-related artery patency with improved cardiac function and survival. Randomized trials of routine intervention after myocardial infarction have generally failed to demonstrate advantages of this invasive approach but methodological problems limit their application to current practice. High-risk patients should be referred for arteriography. While awaiting definitive trials addressing the influence of routine arteriography on patient survival and its cost effectiveness, the management of other patient groups must be individualized.

Journal Article↗
PubMed1998

Likelihood ratios: getting diagnostic testing into perspective.

In modern medicine, sophisticated laboratory tests and imaging studies are often emphasized at the expense of history and physical examination, rather than complementing clinical assessment. Ancillary testing often fails to advance the diagnostic process, and increases patient risk and the expense of medical care. The relative value of clinical evaluation and technological methods is rarely considered, and the power of the clinical evaluation is therefore underestimated. The likelihood ratio (LR) is a semiquantitative measure of the performance of diagnostic tests which indicates how much a diagnostic procedure modifies the probability of disease, and is calculated from the sensitivity and specificity of the test (or directly from the change in probability associated with the test result). We review the performance of frequently-used tests by their LRs, and compare them to the power of clinical assessment, with clinical cases to illustrate the application of LRs in the diagnostic process. The discriminative power of clinical assessment and ancillary tests is often similar, and the combination of the two greatly increases accuracy in the diagnostic process. Clinical assessment is indeed frequently more informative than current technical modalities. LRs assist in putting the value of testing in proper perspective. Practice in evaluating pre-test probabilities of disease and in the application of LRs should be enhanced in medical training.

Diagnostic Techniques and Procedures↗
PubMed1991

Vascular responsiveness and cation exchange in insulin-dependent diabetes.

1. We measured forearm blood flow during brachial artery infusions of vasoconstrictors (angiotensin II and noradrenaline) and vasodilators (sodium nitroprusside and carbachol) in 16 healthy control subjects and in 18 patients with uncomplicated insulin-dependent diabetes mellitus. Erythrocyte Na+/Li+ countertransport and platelet Na+/H+ antiport activities were also measured. 2. The mean basal forearm vascular resistance was 22% lower in diabetic patients than in control subjects. The effects of each infusion on forearm vascular resistance were similar in diabetic patients and control subjects. 3. Erythrocyte Na+/Li+ countertransport activities were similar in diabetic patients and control subjects. Platelet Na+/H+ exchange (Vmax) was approximately 40% greater in diabetic patients than in control subjects, whereas the Km for Na+ was similar. 4. In diabetic patients, but not in control subjects, the responses to sodium nitroprusside and carbachol correlated inversely with Na+/Li+ countertransport in erythrocytes (rs = -0.76, P less than 0.001, and rs = -0.66, P less than 0.005, respectively), but not with Na+/H+ exchange in platelets.

Adult↗