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Yochai Birnbaum

Publications and source records attributed to Yochai Birnbaum.

At least 37 records · Page 2Linked to original sources
PubMed2005

High-frequency QRS electrocardiogram predicts perfusion defects during myocardial perfusion imaging.

BACKGROUND: Changes in high-frequency (HF) QRS components of the electrocardiogram (ECG) (150-250 Hz) are more sensitive than changes in conventional ST segments for detecting myocardial ischemia. We investigated the accuracy of 12-lead HF QRS ECG in detecting perfusion defects during adenosine tetrofosmin myocardial perfusion imaging (MPI). METHODS AND RESULTS: 12-lead HF QRS ECG recordings were obtained from 45 patients before and during adenosine technetium Tc 99m tetrofosmin MPI tests. Before the adenosine infusions, recordings of HF QRS were analyzed according to a morphologic score that incorporated the number, type, and location of reduced amplitude zones (RAZs) present in the 12 leads. During the adenosine infusions, recordings of HF QRS were analyzed according to the maximum percentage changes (in both the positive and negative directions) that occurred in root mean square voltage amplitudes within the 12 leads. The best set of prospective HF QRS criteria had a sensitivity of 94% and a specificity of 83% for correctly identifying the MPI result. The sensitivity of simultaneous ST-segment changes (18%) was significantly lower than that of any individual HF QRS criterion (P < .001). CONCLUSIONS: Analysis of 12-lead HF QRS ECG is highly sensitive and reasonably specific for detecting perfusion defects during adenosine MPI stress tests and significantly more sensitive than analysis of conventional ST segments.

Adenosine↗
PubMed2005

Grade 3 ischemia on admission and absence of prior beta-blockade predict failure of ST resolution following thrombolysis for anterior myocardial infarction.

BACKGROUND: ST segment resolution (STR) is a strong predictor of outcome following thrombolysis. If failure of STR could be predicted on admission, better selection of treatment may be possible. Among patients given reperfusion, those with terminal QRS distortion (grade 3 ischemia) have larger infarcts, but the mechanism underlying this association is unclear. Whether grade 3 ischemia on admission can predict STR is unknown. METHODS: We studied 180 consecutive patients given thrombolysis for a first anterior acute myocardial infarction (AMI). Multiple variables available on admission were analyzed as predictors of STR at 1, 2, and 24 h and as predictors of the need for rescue percutaneous coronary intervention (PCI). RESULTS: Multivariate predictors of failure of STR were: for 1 h: extent of ST elevation (OR: 1.09 [1.01-1.18]); for 2 h: no previous use of beta-blockers (OR: 4.71 [1.56-13.98]) and grade 3 ischemia (OR: 6.77 [3.27-13.95]); for 24 h: previous use of aspirin (OR: 6.70 [1.31-34.01]) and grade 3 ischemia (OR: 29.44 [7.30-118.1]). Grade 3 ischemia had a strong positive predictive value for failure of STR at 1 and 2 h and was the strongest predictor of the need for rescue PCI. CONCLUSIONS: Grade 3 ischemia on admission is the strongest independent predictor of failure to achieve myocardial reperfusion after thrombolysis. This association may underlie the larger infarcts associated with grade 3 ischemia. Other predictors of reperfusion failure are the extent of ST segment elevation, prior use of aspirin and no prior use of beta-blockers.

Adrenergic beta-Antagonists↗
PubMed2005

Benefits, unresolved questions, and technical issues of cardiac resynchronization therapy for heart failure.

This review aims to provide a synthesis of the published evidence regarding the rationale and clinical benefits of cardiac resynchronization therapy (CRT) with implantable atrial-synchronized biventricular pacing (BVP) devices in patients with moderate to advanced heart failure and intra- and interventricular conduction delays. In addition, it addresses clinical and technical issues that have yet to be resolved, such as the selection of the most suitable candidates for CRT; the usefulness of combining BVP with automatic defibrillation backup; the value of CRT in patients with atrial fibrillation; the importance of alternative sites of pacing, such as the atrial septum and the right ventricular (RV) outflow tract; the harmful effects of the long-standing practice of producing an iatrogenic left bundle branch block by conventional RV pacing in patients receiving standard permanent pacemakers; the question of precisely where on the left ventricle optimal pacing is achieved; and the potential applications of CRT in patients with pediatric or congenital heart disease. Considering how major advances have been achieved since the first clinical application of CRT in 1994, one can be optimistic about the future of the electrotherapeutic management of heart failure.

Cardiac Pacing, Artificial↗
PubMed2005

Circulating endothelial progenitor cells and coronary collaterals in patients with non-ST segment elevation myocardial infarction.

BACKGROUND: Endothelial progenitor cells (EPCs) are bone marrow-derived cells that are augmented in response to ischemia and incorporated into neovascularization sites. We sought to determine whether circulating EPCs are related to collateral formation following non-ST segment elevation myocardial infarction (NSTEMI). METHODS: Twenty patients who underwent percutaneous coronary intervention (PCI) within a week of NSTEMI were divided into two groups: patients without collaterals (coll-, n=10) and patients with Rentrop grade 3--4 collaterals (coll+, n=10). Blood samples were drawn before PCI and 24+/- 2 h after PCI. EPC colonies were grown from peripheral blood mononuclear cells, characterized, and counted. Using flow cytometry the percentage of cells co expressing vascular endothelial growth factor receptor-2 and CD 133 was determined. RESULTS: The coll+ group had higher degree of culprit vessel stenosis and lower initial thrombolysis in myocardial infarction flow grade. The relative number of EPCs before PCI was significantly higher in the coll+ group than in the coll- group (1.49 +/- 0.9% vs. 0.77+/- 0.4%, p= 0.045). There were no significant intergroup differences in the number of EPC colony-forming cells. The number of EPC colonies increased in the coll- group after PCI (9.5 +/- 4.8 to 14.0 +/- 5.9/10(6) cells, p=0.01). CONCLUSIONS: This study supports an association between circulating EPC levels and collateral formation in patients with an NSTEMI.

AC133 Antigen↗
PubMed2005

The anteroposterior pericardial sac diameter measured by echocardiography correlates with the volume of pericardial effusion and with effort dyspnea.

AIMS: To examine the value of the anteroposterior pericardial sac diameter (APD) for prediction of the volume of pericardial effusion. METHODS AND RESULTS: We measured the APD by echocardiography before 52 pericardiocentesis procedures and correlated it with the aspirate volume, etiology, symptoms, and clinical outcome. The volume of the aspirate ranged from 60 to 2300 ml (median 650 ml). The APD (range 8.0 cm-15.9 cm, median 12 cm) correlated well with the cubic root of the volume of the effusion [volume=(0.8APD-0.6)3, r2=0.533, p<0.01]. An APD>or=12 cm had a positive predictive value of 88% and a negative predictive value of 83% for effusion volume above the sample median (>or=650 ml) and a positive predictive value of 100% for effusion in the middle or upper aspirate volume tertiles. Effort dyspnea was more common among patients with APD>or=12.0 cm (n=13) than in those with APD<12.0 cm (n=11) (p=0.007). One-year survival after pericardiocentesis was closely related to the severity of the underlying etiology and was not influenced by the volume of the effusion before aspiration. CONCLUSIONS: The APD is a simple, valuable method for non-invasive prediction of pericardial fluid volume. A greater APD is associated with, and may explain, effort dyspnea.

Adult↗
PubMed2005

Prostaglandins mediate the cardioprotective effects of atorvastatin against ischemia-reperfusion injury.

OBJECTIVES: Statins attenuate myocardial ischemic injury by activating nitric oxide synthase (NOS). It is unknown whether cyclooxygenase-2 (COX2), which mediates late ischemic preconditioning, also mediates statins-induced cardioprotection. We investigated the involvement of the prostaglandins and NOS in the cardioprotective effect of atorvastatin (ATV) in the rat. METHODS: Sprague-Dawley rats were randomized to a 3-day oral treatment with ATV 10 mg/kg, valdecoxib, a selective COX2 inhibitor (VAL) 3 mg/kg, ATV+VAL or water alone. Rats underwent 30-min myocardial ischemia followed by 4-h reperfusion. RESULTS: Infarct size was smaller in the ATV group (31.3+/-1.9%) than controls (44.5+/-3.1%; p=0.011) and VAL (44.5+/-3.1%; p=0.008). VAL attenuated the protective effect of ATV when administered together (40.2+/-2.5%). ATV pretreatment increased myocardial content of 6-keto-PGF(1alpha) (69.5+/-1.5 pg/mg) and PGE2 (57.9+/-0.6 pg/mg) compared with controls (16.2+/-0.2 and 42.1+/-2.0 pg/mg, respectively) and ATV+VAL (15.8+/-0.3 and 39.9+/-1.9 pg/mg, respectively). ATV increased myocardial content of cytosolic phospholipase A2 (cPLA2) (174.8+/-0.5%), COX2 (446.2+/-0.9%), PGI2 synthase (201.8+/-1.1%) and PGE2 synthase (122+/-0.7%), whereas ATV+VAL did not (123.0+/-7.9%, 93.8+/-8.5%, 103.0+/-1.6% and 99.0+/-0%, respectively). ATV did not change the myocardial content of eNOS and nNOS, but increased the concentration of phosphorylated eNOS (231.8+/-2.4%) and iNOS (154.5+/-1.2%). This effect was not blocked by coadministration of VAL (231.5+/-3.0% and 154.5+/-1.8%, respectively). CONCLUSIONS: Our results suggest that the prostaglandins are essential for mediating the myocardial protective effects of ATV and their production is downstream to eNOS phosphorylation and iNOS.

Animals↗
PubMed2005

Electrocardiographic infarct size assessment after thrombolysis: insights from the Acute Myocardial Infarction STudy ADenosine (AMISTAD) trial.

BACKGROUND: Noninvasive methods are needed to evaluate reperfusion success in patients with acute myocardial infarction (MI). The AMISTAD trial was analyzed to compare MI size and myocardial salvage determined by electrocardiogram (ECG) with technetium Tc 99m sestamibi single-photon emission computerized tomography (SPECT) imaging. METHODS: Of 236 patients enrolled in AMISTAD, 166 (70 %) with no ECG confounding factors and no prior MI were included in this analysis. Of these, group 1 (126 patients, 53%) had final infarct size (FIS) available by both ECG and SPECT. Group 2 (56 patients, 24%) had myocardium at risk, FIS, and salvage index (SI) assessed by both SPECT and ECG techniques. Aldrich/Clemmensen scores for myocardium at risk and the Selvester QRS score for final MI size were used. Salvage index was calculated as follows: SI = (myocardium at risk-FIS)/(myocardium at risk). RESULTS: In group 1, FIS was 15% (6, 24) as measured by ECG and 11% (2, 27) as measured by SPECT. In the adenosine group, FIS was 12% (6, 21) and 11% (2, 22). In the placebo group, FIS was 16.5% (7.5, 24) and 11.5% (3.0, 38.5) by ECG and SPECT, respectively. The overall correlation between SPECT and ECG for FIS was 0.58 (P = .0001): 0.60 in the placebo group (P = .0001) and 0.54 (P = .0001) in the adenosine group. In group 2, myocardium at risk was 23% (17, 30) and 26% (10, 50) with ECG and SPECT, respectively (P = .0066). Final infarct size was 17% (6, 21) and 12% (1, 24) (P < .0001). The SI was 29% (-7, 57) and 46% (15, 79) with ECG and SPECT, respectively (P = .0510). CONCLUSIONS: The ECG measurement of infarct size has a moderate relationship with SPECT infarct size measurements in the population with available assessments. This ECG algorithm must further be validated on clinical outcomes.

Adenosine↗
PubMed2005

Electrocardiogram of acute ST-elevation myocardial infarction: the significance of the various "scores".

The Electrocardiogram has extensively been used for evaluation and triage of patients with acute chest pain. The clinician admitting a patient with ST elevation acute myocardial infarction should be able to estimate the size and location of the ischemic area at risk, how much of the ischemic myocardium has already undergone irreversible necrosis by the time of presentation, and the "severity of ischemia" (or what is the rate of progression of necrosis as long as ischemia continues). The electrocardiographic variables that are used to make these estimates are the initial portion of the QRS (Q and R waves), the terminal portion of the QRS (the S waves and the J-point), the ST segment, and the configuration of the T waves. This editorial discuss the ability to predict each of the "physiological" parameters using the above mentioned electrocardiographic variables.

Electrocardiography↗
PubMed2005

Grade 3 ischemia on the admission electrocardiogram predicts rapid progression of necrosis over time and less myocardial salvage by primary angioplasty.

BACKGROUND: Among patients with ST-elevation acute myocardial infarction, those with terminal QRS distortion (grade 3 ischemia) have higher mortality and larger infarct size (IS) than patients without QRS distortion (grade 2 ischemia). METHODS: We assessed the relation of baseline electrocardiographic ischemia grades to area at risk (AR) and myocardial salvage [100 (AR-IS)/AR] in 79 patients who underwent primary angioplasty for first ST-elevation acute myocardial infarction and had technetium Tc 99m sestamibi single-photon emission computed tomography before angioplasty (AR) and at predischarge (IS). Patients were classified as having grade 2 ischemia (ST elevation without terminal QRS distortion in any of the leads, n = 48), grade 2.5 ischemia (ST elevation with terminal QRS distortion in 1 lead, n = 16), or grade 3 ischemia (ST elevation with terminal QRS distortion in >2 adjacent leads, n = 15). RESULTS: Time to treatment was comparable among groups. AR was comparable among groups (38% +/- 20%, 33% +/- 23%, and 34% +/- 23%, respectively; P = .70). There were no differences among groups in residual myocardial perfusion (severity index 0.28 +/- 0.12, 0.29 +/- 0.16, and 0.30 +/- 0.15 in grades 2, 2.5, and 3 ischemia, respectively; P = .97). In contrast, there was a trend toward lower myocardial salvage (45% +/- 32%) in the grade 3 group than in the grade 2 (65% +/- 33%) and grade 2.5 (65% +/- 40%) groups ( P = .16). Salvage was dependent on time only in the grade 3 group. Spearman rank correlation coefficients between time to treatment and percentage salvage were 0.003 ( P = .99), -0.24 ( P = .38), and -0.63 ( P = .022) for grades 2, 2.5, and 3, respectively. CONCLUSIONS: Patients with grade 3 ischemia have rapid progression of necrosis over time and less myocardial salvage. This admission pattern is a predictor of myocardial salvage by primary angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed2005

An unusual electrocardiogram artifact: what is its source?

A diabetic female presented with nausea and vomiting. Her electrocardiogram showed sinus rhythm with two artifactual spikes, not synchronized with the cardiac rhythm. The patient had an implanted gastric electrical stimulation system for treating her diabetic gastroparesis. Recent DC shock for ventricular fibrillation during coronary angiography caused malfunction of the gastric pacemaker.

Artifacts↗
PubMed2005

Ischemia-induced ST-segment elevation: classification, prognosis, and therapy.

The standard 12-lead electrocardiogram (ECG) remains the most useful tool for the diagnosis, early risk stratification, triage, and guidance of therapy in patients with acute coronary syndromes. However, the initial and the terminal part of the QRS complex, the ST segments, and the T waves are influenced by anatomical and metabolic factors such as the "myocardium at risk" and "severity" and "duration" of ischemia. Moreover, there are complex interactions between all these factors. The ECG can identify potential candidates for reperfusion therapy as well as the completeness and success of reperfusion, whereas it can also identify those patients who will have no benefit from reperfusion because of either late arrival or nonischemic etiologies of ECG changes. These patients may have a "pseudo" ST-elevation acute myocardial infarction (STEAMI) or "pseudo-pseudo" STEAMI. The presence of Q waves and additional ST-segment depression and T-wave inversion on the admission ECG in patients with STEAMI may provide us information regarding the potential myocardial reserves, and various ECG scoring systems are in current use for that purpose. The pattern and timing of changes in Q waves, ST segment, and T waves may all be markers of the patency status of the infarct-related artery. We review and discuss each of the dynamic ECG variables during ischemia and reperfusion: the initial QRS (Q and R waves), the terminal QRS (Sclarovsky-Birnbaum score), the ST segment, and the T waves.

Electrocardiography↗
PubMed2005

Reperfusion-related polymorphic ventricular tachycardia as a possible mechanism of sudden death in patients with anomalous coronary arteries.

We describe a patient with anomalous origin of the left coronary artery in whom polymorphic ventricular tachycardia developed immediately after an episode of chest pain with ST segment elevation. This is the first report providing direct evidence that reperfusion arrhythmias may be the cause of sudden death in individuals with anomalous coronary arteries.

Coronary Vessel Anomalies↗
PubMed2005

Color M-mode flow propagation velocity and conventional doppler indices in the assessment of diastolic left ventricular function during isometric exercise.

BACKGROUND AND OBJECTIVE: Color M-mode flow propagation velocity (Vp) was shown to be a preload-independent measure of diastolic function. To study the effects of an increase in afterload induced by isometric handgrip exercise on diastolic function assessment in patients with cardiomyopathy, we measured Vp and conventional Doppler indices at baseline and at 30% of predetermined maximum handgrip strength. METHODS: Twenty-four patients with systolic dysfunction were divided into two groups: Group I comprising 12 patients with E/A < 1 (early filling velocity/atrial contraction velocity) and Group II comprising 12 patients with E/A > 1. All the patients underwent measurement of Vp, E velocity, its deceleration time (DT), A velocity, isovolumic relaxation time (IVRT), and pulmonary atrial flow reversal velocity (PFR) at baseline and at 30% of predetermined maximum handgrip strength. Twelve healthy controls underwent these same measurements. RESULTS: When comparing baseline to peak echocardiographic data, no significant changes were noted in Vp in any of the groups while a shift of pulsed Doppler indices of Group I toward a pattern closer to that of Group II was noted and a decrease in E velocity and E/A ratio with an increase in IVRT occurred in healthy controls. CONCLUSIONS: Color M-mode flow propagation velocity seems to be an afterload-independent measure of diastolic function in patients with moderate to severe cardiomyopathy while pulsed Doppler indices are more sensitive to loading conditions induced by isometric exercise.

Blood Flow Velocity↗
PubMed2004

The renal patient with coronary artery disease: current concepts and dilemmas.

The patient with chronic kidney disease and coronary artery disease (CAD) presents special challenges. This report reviews the scope of the challenge, the hostile internal milieu predisposing to CAD and cardiac events, management issues, unresolved dilemmas, and the need for randomized trials to allow for evidence-based treatment.

Angioplasty, Balloon, Coronary↗
PubMed2004

Comparison of frequency of left ventricular wall motion abnormalities in patients with a first acute myocardial infarction with versus without left ventricular hypertrophy.

One hundred fifty patients with their first acute myocardial infarctions (AMIs) were studied. AMIs were confirmed by troponin levels, ST-segment elevation, or angiographic coronary occlusion. In 36% of patients (16 of 45) with left ventricular (LV) hypertrophy, the wall motion score index was normal, whereas in patients with no LV hypertrophy, only 18% (19 of 105) had no segmental wall motion abnormalities (p = 0.03). When adjusting for troponin level, the odds ratio for normal wall motion of patients with LV hypertrophy was 2.86 (95% confidence interval 1.26 to 6.50) compared with those with normal wall thickness. Consequently, normal LV wall motion by echocardiography in the setting of LV hypertrophy does not exclude AMI.

Aged↗
PubMed2004

Rapid screening of cardiac patients with a miniaturized hand-held ultrasound imager--comparisons with physical examination and conventional two-dimensional echocardiography.

BACKGROUND: Rapid screening of cardiac patients with a hand-held ultrasound imager (SonoHeart [SH]) could provide valuable clinical information. HYPOTHESIS: Whether the use of this device yields additional information to a carefully conducted physical examination and comparable findings to those of conventional two-dimensional echocardiography (2-D) during inpatient rounds is not well established and is the subject of this study. METHODS: In all, 100 consecutive telemetry patients underwent rapid screening with 2-D and color Doppler SH during inpatient rounds. SonoHeart findings were compared with results from conventional 2-D and physical examination conducted by an attending cardiologist. RESULTS: All patients had interpretable images. Mean scanning time with SH was 5.0 +/- 1.2 min; 2-D and SH findings were comparable. The parameters studied included chamber sizes, left ventricular (LV) systolic function, presence of LV hypertrophy (LVH), wall motion abnormalities (WMA), pericardial effusion (PE), and valvular regurgitations. Mild to moderate valvular regurgitation and LV systolic dysfunction were reliably diagnosed by SH in a number of patients whose symptoms were unrelated to the abnormalities detected. CONCLUSIONS: Rapid screening with SH provides accurate and valuable information that would otherwise be undetected during physical examination. Its introduction into clinical practice may redefine the initial approach to patients with cardiovascular disease.

Cardiovascular Diseases↗