Usefulness of Oximetry Paradoxus to Diagnose Cardiac Tamponade.

Although echocardiography is usually diagnostic of cardiac tamponade, it may not be readily available at the point-of-care. We sought to develop and validate a measurement of respirophasic variation in the amplitude of pulse oximetry plethysmographic waveforms as a diagnostic tool for cardiac tamponade. Pulse oximetry plethysmographic waveforms were recorded, and the ratio of maximum-to-minimum measured amplitude of these waveforms from one respiratory cycle was calculated by blinded observers. Ratios from 3 consecutive respiratory cycles were then averaged to derive an "oximetry paradoxus" ratio. Cardiac tamponade was independently confirmed or excluded according to a "blinded" objective interpretation of echocardiography or right heart catheterization. Seventy four subjects were enrolled (51% men; mean age 54 ± 15 years); 19 of whom had cardiac tamponade. Oximetry paradoxus area under the curve for diagnosis of cardiac tamponade was 0.90 (95% confidence interval, 0.84 to 0.97); its diagnostic performance was superior to sphygmomanometer-measured pulsus paradoxus (area under the curve difference = 0.16, p = 0.022). In a derivation cohort (n = 37; tamponade, 9 cases), 3 diagnostic oximetry paradoxus thresholds were identified and validated in an independent validation cohort (n = 37; tamponade, 10 cases): 1.2 (100% sensitivity, 44% specificity), 1.5 (80% sensitivity, 81% specificity), and 1.7 (80% sensitivity, 89% specificity). Furthermore, oximetry paradoxus was significantly reduced after draining pericardial fluid. In conclusion, we defined and validated oximetry paradoxus as a simple and ubiquitous point-of-care test to diagnose cardiac tamponade using respirophasic changes in pulse plethysmography waveforms. This test can aid in identifying patients with cardiac tamponade, thus expediting confirmatory testing and life-saving treatment.

Can emergency physicians diagnose and correctly classify diastolic dysfunction using bedside echocardiography?

OBJECTIVES: The goal of this study was to determine if emergency physicians (EPs) can correctly perform a bedside diastology examination (DE) and correctly grade the level of diastolic function with minimal additional training in echocardiography beyond what is learned in residency. We hypothesize that EPs will be accurate at detecting and grading diastolic dysfunction (DD) when compared to a criterion standard interpretation by a cardiologist. METHODS: We conducted a prospective, observational study on a convenience sample of adult patients who presented to an urban emergency department with a chief concern of dyspnea. All patients had a bedside echocardiogram, including a DE, performed by an EP-sonographer who had 3 hours of didactic and hands-on echocardiography training with a cardiologist. The DE was interpreted as normal, grade 1 to 3 if DD was present, or indeterminate, all based on predefined criteria. This interpretation was compared to that of a cardiologist who was blinded to the EPs' interpretations. RESULTS: We enrolled 62 patients; 52% had DD. Using the cardiology interpretation as the criterion standard, the sensitivity and specificity of the EP-performed DE to identify clinically significant diastolic function were 92% (95% confidence interval [CI], 60-100) and 69% (95% CI, 50-83), respectively. Agreement between EPs and cardiology on grade of DD was assessed using κ and weighted κ: κ = 0.44 (95% CI, 0.29-0.59) and weighted κ = 0.52 (95% CI, 0.38-0.67). Overall, EPs rated 27% of DEs as indeterminate, compared with only 15% by cardiology. For DEs where both EPs and cardiology attempted an interpretation (indeterminates excluded) κ = 0.45 (95% CI, 0.26 to 0.65) and weighted κ = 0.54 (95% CI, 0.36-0.72). CONCLUSION: After limited diastology-specific training, EPs are able to accurately identify clinically significant DD. However, correct grading of DD, when compared to a cardiologist, was only moderate, at best. Our results suggest that further training is necessary for EPs to achieve expertise in grading DD.

Inferior vena cava diameter change after intravenous furosemide in patients diagnosed with acute decompensated heart failure.

PURPOSE: Measurement of the inferior vena cava (IVC) diameters may improve decision-making for patients hospitalized with acute decompensated heart failure. Nevertheless, little is known about how the IVC is affected by loop diuretics. We sought to determine if bolus infusions of intravenous furosemide affect IVC diameters measured by hand-carried ultrasonography. METHODS: We conducted a prospective cohort study at a public teaching hospital from September 2009 through June 2010. Physician investigators performed IVC ultrasonography on a convenience sample of 70 hospitalized adults who were prescribed intravenous furosemide for the diagnosis of acute decompensated heart failure. RESULTS: Participants' median baseline IVC diameter was 2.38 cm (interquartile range, 1.91-2.55 cm). At 1-2 hours after furosemide, IVC diameters decreased an average of 0.21 cm (95% CI, 0.13-0.29 cm) and remained significantly below baseline at 2-3 hours after furosemide by an average of 0.15 cm (95% CI, 0.07-0.22 cm). CONCLUSIONS: IVC diameters of adults diagnosed with acute decompensated heart failure become measurably smaller after single doses of intravenous furosemide. Whether this represents a true change in volume status has not been studied.

Diagnostic accuracy retrospectively of electrocardiographic findings and cancer history for tamponade in patients determined to have pericardial effusion by transthoracic echocardiogram.

Unexpected pericardial effusions are often found by frontline providers who perform computed tomography. To study the hypothesis that electrocardiographic findings and whether cancer is known or suspected importantly change the likelihood of tamponade for such providers, all unique patients with moderate or large pericardial effusions determined by transthoracic echocardiography during a 6-year period were retrospectively identified. Electrocardiograms were evaluated by blinded investigators for electrical alternans (total and QRS), low voltage (limb leads only, precordial leads only, and both), and tachycardia (>100 QRS complexes/min). Medical records were reviewed to determine whether cancer was known or suspected and whether tamponade was diagnosed. Tamponade was present in 66 patients (27% of 241) with moderate or large pericardial effusions. No tachycardia lowered the odds of tamponade the most (likelihood ratio 0.4, 95% confidence interval 0.3 to 0.6) but by a degree less than any single diagnostic element increased it when present. The combined presence of all 3 electrocardiographic findings and cancer increased the odds of tamponade 63-fold (likelihood ratio 63, 95% confidence interval 33 to 150), whereas their combined absence decreased the odds only fivefold (likelihood ratio 0.2, 95% confidence interval 0.2 to 0.3). In conclusion, electrocardiography findings and cancer rule in tamponade better than they rule it out. Combining these diagnostic elements improves their discriminatory power but not sufficiently enough to rule out tamponade in patients with moderate or large pericardial effusions.

Attenuation of the side effect profile of regadenoson: a randomized double-blind placebo-controlled study with aminophylline in patients undergoing myocardial perfusion imaging and have severe chronic kidney disease--the ASSUAGE-CKD trial.

A subgroup analysis of the ASSUAGE trial suggested that the standardized intravenous aminophylline administration following regadenoson-stress leads to substantial attenuation of regadenoson adverse-effects in patients with severe chronic kidney disease (CKD). In a randomized, double-blinded, placebo-controlled clinical trial of patients with stage 4 and 5 CKD, we compared the frequency and severity of regadenoson adverse-effects in those who received 75 mg of intravenous aminophylline versus a matching placebo administered 90 s post-radioisotope injection. Consecutive 300 patients with severe CKD (36% women; 86% end-stage renal disease; age 55 (±13) years) were randomized to receive aminophylline (n = 150) or placebo (n = 150). In the aminophylline arm, there was 65% reduction in the incidence of the primary endpoint of diarrhea (9 (6.0%) vs. 26 (17.3%), P = 0.002), 51% reduction in the secondary endpoint of any regadenoson adverse-effect (47 (31.3%) vs. 96 (64%), P < 0.001) and 70% reduction in headache (16 (10.7%) vs. 54 (36%), P < 0.001). The stress protocol was better tolerated in the aminophylline group (P = 0.008). The quantitative summed difference score, as a measure of stress-induced ischemic burden, was similar between the study groups (P = 0.51). In conclusion, the routine standardized administration of intravenous aminophylline in patients with severe CKD substantially reduces the frequency and severity of the adverse-effects associated with regadenoson-stress without changing the ischemic burden. [NCT01336140].

Hand-carried echocardiography by hospitalists: a randomized trial.

BACKGROUND: Hospitalists can use hand-carried echocardiography for accurate point-of-care information, but patient outcome data for its application are sparse. METHODS: We performed an unblinded, parallel-group randomized trial between July 2008 and March 2009 at one teaching hospital in Chicago, Illinois. We randomly assigned adult general medicine inpatients referred for standard echocardiography with indications investigatable by hand-carried echocardiography to care guided by hand-carried echocardiography or usual care. The main outcome measure was length of stay on the referring hospitalist's service. Secondary outcomes included a before-after analysis of reported changes in management due to hand-carried echocardiography and the diagnostic accuracy of hand-carried echocardiography. RESULTS: The difference in length of stay between 226 participants randomized to care guided by hand-carried echocardiography (geometric mean 46.1 hours, interquartile range 29.0-70.9 hours) and 227 participants randomized to usual care (46.9 hours, interquartile range 34.1-68.3 hours) corresponded to a 1.7% reduction in length of stay that was not statistically significant (95% confidence interval, -12.1 to 9.8%). In post hoc subgroup analyses, care guided by hand-carried echocardiography reduced length of stay in participants who were referred for heart failure (P=.0008). Among participants who underwent both hand-carried and standard echocardiography, hospitalists changed management due to hand-carried echocardiography in 37%. Despite the favorable diagnostic accuracy of hand-carried echocardiography, most changes to the timing of hospital discharge occurred after standard echocardiography. CONCLUSION: Hospitalist care guided by hand-carried echocardiography for unselected general medicine patients does not meaningfully affect length of stay. Whether or not it affects care quality remains unstudied.

Predictors of diastolic dysfunction among minority patients with newly diagnosed type 2 diabetes.

AIM: To determine mutable risk factors for asymptomatic diastolic dysfunction in ethnic minority patients newly diagnosed with type 2 diabetes. METHODS: We recruited consecutive adults with newly diagnosed diabetes who had no signs or symptoms or history of heart disease. All patients received standardized evaluation including interview, physical examination, laboratory tests and echocardiogram with tissue Doppler studies. We used logistic regression models to identify mutable risk factors for diastolic dysfunction. RESULTS: Among 126 study subjects (52% women, age 45+/-10 years, BMI 33+/-7, 42% with hypertension, 100% ejection fraction > or =50%), evidence of diastolic dysfunction was present in 64 (51%). After controlling for age, heart rate and blood pressure, independent predictors of diastolic dysfunction included physical inactivity (OR: 2.3; 95% CI: 0.9-6.1; P=0.08) and glucose (OR: 4.9; 95% CI: 1.4-17.8; P=0.02). Physical inactivity was associated with early diastolic dysfunction (impaired relaxation), whereas epicardial fat thickness and glucose levels were associated with late diastolic dysfunction (impaired compliance). The hs-CRP and BNP levels were not associated with diastolic dysfunction. CONCLUSIONS: Asymptomatic diastolic dysfunction was prevalent among urban minority patients newly diagnosed with diabetes. Important differences exist among factors that affect early and late diastolic function that may have prognostic and therapeutic implications.

Diagnostic accuracy of hospitalist-performed hand-carried ultrasound echocardiography after a brief training program.

BACKGROUND: The duration of training needed for hospitalists to accurately perform hand-carried ultrasound echocardiography (HCUE) is uncertain. OBJECTIVE: To determine the diagnostic accuracy of HCUE performed by hospitalists after a 27-hour training program. DESIGN: Prospective cohort study. SETTING: Large public teaching hospital. PATIENTS: A total of 322 inpatients referred for standard echocardiography (SE) between March and May 2007. INTERVENTION: Blinded to SE results, attending hospitalist physicians performed HCUE within hours of SE. MEASUREMENTS: Diagnostic characteristics of HCUE as a test for 6 cardiac abnormalities assessed by SE: left ventricular (LV) systolic dysfunction; severe mitral regurgitation (MR); moderate or severe left atrium (LA) enlargement; moderate or severe LV hypertrophy; medium or large pericardial effusion; and dilatation of the inferior vena cava (IVC). RESULTS: A total of 314 patients underwent both SE and HCUE within a median time of 2.8 hours (25th to 75th percentiles, 1.4 to 5.1 hours). Positive and negative likelihood ratios for HCUE increased and decreased, respectively, the prior odds by 5-fold or more for LV systolic dysfunction, severe MR regurgitation, and moderate or large pericardial effusion. Likelihood ratios changed the prior odds by 2-fold or more for moderate or severe LA enlargement, moderate or severe LV hypertrophy, and IVC dilatation. Indeterminate HCUE results occurred in 2% to 6% of assessments. CONCLUSIONS: The diagnostic accuracy of HCUE performed by hospitalists after a brief training program was moderate to excellent for 6 important cardiac abnormalities.

Taser X26 discharges in swine: ventricular rhythm capture is dependent on discharge vector.

BACKGROUND: Data from our previous studies indicate that Taser X26 stun devices can acutely alter cardiac function in swine. We hypothesized that most transcardiac discharge vectors would capture ventricular rhythm, but that other vectors, not traversing the heart, would fail to capture the ventricular rhythm. METHODS: Using an Institutional Animal Care and Use Committee (IACUC) approved protocol, four Yorkshire pigs (25-36 kg) were anesthetized, paralyzed with succinylcholine (2 mg/kg), and then exposed to 10 second discharges from a police-issue Taser X26. For most discharges, the barbed darts were pushed manually into the skin to their full depth (12 mm) and were arranged in either transcardiac (such that a straight line connecting the darts would cross the region of the heart) or non-transcardiac vectors. A total of 11 different vectors and 22 discharge conditions were studied. For each vector, by simply rotating the cartridge 180-degrees in the gun, the primary current-emitting dart was changed and the direction of current flow during the discharge was reversed without physically moving the darts. Echocardiography and electrocardiograms (ECGs) were performed before, during, and after all discharges. p values < 0.05 were considered significant. RESULTS: ECGs were unreadable during the discharges because of electrical interference, but echocardiography images clearly demonstrated that ventricular rhythm was captured immediately in 52.5% (31 of 59) of the discharges on the ventral surface of the animal. In each of these cases, capture of the ventricular rhythm with rapid ventricular contractions consistent with ventricular tachycardia (VT) or flutter was seen throughout the discharge. A total of 27 discharges were administered with transcardiac vectors and ventricular capture occurred in 23 of these discharges (85.2% capture rate). A total of 32 non-transcardiac discharges were administered ventrally and capture was seen in only eight of these (25% capture rate). Ventricular fibrillation (VF) was seen with two vectors, both of which were transcardiac. In the remaining animals, VT occurred postdischarge until sinus rhythm was regained spontaneously. CONCLUSIONS: For most transcardiac vectors, Taser X26 caused immediate ventricular rhythm capture. This usually reverted spontaneously to sinus rhythm but potentially fatal VF was seen with two vectors. For some non-transcardiac vectors, capture was also seen but with a significantly (p < 0.0001) decreased incidence.

TASER X26 discharges in swine produce potentially fatal ventricular arrhythmias.

OBJECTIVES: Data from the authors and others suggest that TASER X26 stun devices can acutely alter cardiac function in swine. The authors hypothesized that TASER discharges degrade cardiac performance through a mechanism not involving concurrent acidosis. METHODS: Using an Institutional Animal Care and Use Committee (IACUC)-approved protocol, Yorkshire pigs (25-71 kg) were anesthetized, paralyzed with succinylcholine (SCh; 2 mg/kg), and then exposed to two 40-second discharges from a TASER X26 with a transcardiac vector. Vital signs, blood chemistry, and electrolyte levels were obtained before exposure and periodically for 48 hours postdischarge. Electrocardiograms and echocardiography (echo) were performed before, during, and after the discharges. p-Values < 0.05 were considered significant. RESULTS: Electrocardiograms were unreadable during the discharges due to electrical interference, but echo images showed unmistakably that cardiac rhythm was captured immediately at a rate of 301 +/- 18 beats/min (n = 8) in all animals tested. Capture continued for the duration of the discharge and in one animal degenerated into fatal ventricular fibrillation (VF). In the remaining animals, ventricular tachycardia (VT) occurred postdischarge for 1-17 seconds, whereupon sinus rhythm was regained spontaneously. Blood chemistry values and vital signs were minimally altered postdischarge and no significant acidosis was seen. CONCLUSIONS: Extreme acid-base disturbances usually seen after lengthy TASER discharges were absent with SCh, but TASER X26 discharges immediately and invariably produced myocardial capture. This usually reverted spontaneously to sinus rhythm postdischarge, but fatal VF was seen in one animal. Thus, in the absence of systemic acidosis, lengthy transcardiac TASER X26 discharges (2 x 40 seconds) captured myocardial rhythm, potentially resulting in VT or VF in swine.

Baseline left bundle branch block with right bundle branch escape complexes in a patient with coronary artery disease, presents like an alternating bundle branch block: a case report.

Alternating bundle branch block (ABBB) is a less commonly encountered phenomenon with the advent of re-perfusion therapy for acute myocardial infarction. ECGs simulating the appearance of an ABBB need to be carefully analysed. We present an ECG showing a baseline Left Bundle Branch Block(LBBB) progressing to a high grade AV block with escape complexes having a Right Bundle Branch Block (RBBB) morphology. Such an ECG can be mistaken for an ABBB if not analysed carefully.