Flecainide associated torsade de pointes: A potential case of reverse use dependence.

Flecainide has been known to cause torsades de pointes (TdP) in patients with structural heart disease and its mechanism has been attributed to use-dependency. We present a patient with flecainide-induced TdP in the absence of any other precipitating factors. This case highlights potential reverse use dependence associated with flecainide resulting in TdP.

Successful microbubble sonothrombolysis without tissue-type plasminogen activator in a rabbit model of acute ischemic stroke.

BACKGROUND AND PURPOSE: Microbubbles (MB) combined with ultrasound (US) have been shown to lyse clots without tissue-type plasminogen activator (tPA) both in vitro and in vivo. We evaluated sonothrombolysis with 3 types of MB using a rabbit embolic stroke model. METHODS: New Zealand White rabbits (n=74) received internal carotid angiographic embolization of single 3-day-old cylindrical clots (0.6 × 4.0 mm). Groups included: (1) control (n=11) embolized without treatment; (2) tPA (n=20); (3) tPA+US (n=10); (4) perflutren lipid MB+US (n=16); (5) albumin 3 µm MB+US (n=8); and (6) tagged albumin 3 µm MB+US (n=9). Treatment began 1 hour postembolization. Ultrasound was pulsed-wave (1 MHz; 0.8 W/cm²) for 1 hour; rabbits with tPA received intravenous tPA (0.9 mg/kg) over 1 hour. Lipid MB dose was intravenous (0.16 mg/kg) over 30 minutes. Dosage of 3 µm MB was 5 × 109 MB intravenously alone or tagged with eptifibatide and fibrin antibody over 30 minutes. Rabbits were euthanized at 24 hours. Infarct volume was determined using vital stains on brain sections. Hemorrhage was evaluated on hematoxylin and eosin sections. RESULTS: Infarct volume percent was lower for rabbits treated with lipid MB+US (1.0%± 0.6%; P=0.013), 3 µm MB+US (0.7% ± 0.9%; P=0.018), and tagged 3 µm MB+US (0.8% ± 0.8%; P=0.019) compared with controls (3.5%± 0.8%). The 3 MB types collectively had lower infarct volumes (P=0.0043) than controls. Infarct volume averaged 2.2% ± 0.6% and 1.7%± 0.8% for rabbits treated with tPA alone and tPA+US, respectively (P=nonsignificant). CONCLUSIONS: Sonothrombolysis without tPA using these MB is effective in decreasing infarct volumes. Study of human application and further MB technique development are justified.

The pocket echocardiograph: a pilot study of its validation and feasibility in intubated patients.

BACKGROUND: The clinical use of miniaturized echocardiograph devices is expanding due to the potential to rapidly assess cardiac function in the critically ill patient. Novice echocardiographers have used the pocket echocardiograph (PE) to estimate ejection fraction in ambulatory patients, but have not evaluated intubated patients. We hypothesize that a novice echocardiographer can use PE to acquire interpretable cardiac images, and provide an accurate tool for estimating ejection fraction. METHODS: Subjects scheduled for cardiac surgery underwent blinded transesophageal echocardiography (TEE) and PE during a hemodynamically stable period after endotracheal intubation prior to incision. A single cardiology fellow acquired all PE images. The fellow and an experienced echocardiographer interpreted PE studies offline in a blinded fashion, visually estimating ejection fraction and assigning an image quality grade. Comparisons were made to the TEE study. RESULTS: Subjects (n = 22) were 81% male; age 69 ± 9 years, and had a mean ejection fraction of 51% ± 10.0%. Parasternal images were adequate in the vast majority of patients (77%), limited in 14%, and unacceptable in 9%, while apical (41%, 45%, and 14%) and subcostal (36%, 32%, and 32%) image quality was inferior. Ejection fraction showed fair correlation, bias, and limits of agreement for the fellow's interpretation (r = 0.50, 4.9%, ± 20.7%), with stronger association for the experienced echocardiographer (r = 0.76, 3.3%, ± 16.6%). CONCLUSION: A novice echocardiographer using PE can acquire interpretable images in the majority of intubated patients. Novice and expert echocardiographers can reasonably estimate ejection fraction using PE. PE may allow novice echocardiographers to rapidly assess cardiac function in intubated patients.

Effect of renal function on survival after implantable cardioverter defibrillator placement.

Implantable cardioverter defibrillators (ICDs) are effective at reducing arrhythmic death in patients with left ventricular dysfunction, but few studies have investigated the outcomes after ICD implantation in patients with chronic kidney disease (CKD). We conducted a 2-center retrospective study of 958 patients who had undergone ICD placement for primary prevention from the 2000 to 2006. The patients were stratified into 5 groups according to the CKD stage (stage 1, glomerular filtration [GFR] 90 to 120 ml/min; stage 2, GFR 60 to 89 ml/min; stage 3, GFR 30 to 59 ml/min; stage 4, GFR 15 to 29 ml/min; and stage 5, GFR 0 to 14 ml/min). The primary end point was death at 1 year. Of the 958 patients included in our analysis, 73 (7.6%) had died at 1 year. The mortality rate at 1 year increased with worsening CKD (1.8%, 5.3%, 9.0%, 22%, and 38% for stage 1 to 5, respectively, p <0.0001 for group). CKD was an independent predictor of mortality; hazard ratio 1.0, 1.075 (95% confidence interval 0.578 to 2.0), 1.372 (95% confidence interval 0.736 to 2.556), 3.092 (95% confidence interval 1.52 to 6.29), and 10.15 (95% confidence interval 4.25 to 24.23) for stage 1 to 5, respectively (p <0.0001 for group). Patients with CKD and left ventricular dysfunction have a poor prognosis despite ICD placement. The 1-year mortality increased as the renal function decreased. In conclusion, physicians should be cognizant of the prognosis when considering whether an ICD should be implanted in patients with CKD.

Comparison of the endotracheal cardiac output monitor to thermodilution in cardiac surgery patients.

OBJECTIVES: To compare cardiac output (CO) measurements from a novel endotracheal bioimpedance cardiac output monitor device (ECOM; ConMed, Irvine, CA) to simultaneous pulmonary artery thermodilution (TD) CO. DESIGN: Prospective study. SETTING: One academic hospital. PARTICIPANTS: Forty volunteer patients undergoing cardiac surgery. INTERVENTIONS: Intraoperative CO measurements. MEASUREMENTS AND MAIN RESULTS: Simultaneous comparative data points were collected from ECOM and TD at 4 periods: post-induction, post-sternotomy, post-cardiopulmonary bypass, and post-chest closure. The mean CO(TD) was compared with CO(ECOM) for each operative period then assessed for agreement by linear regression, Bland-Altman analysis, and percent error methods. There were 35 men (87.5%) with a mean age of 66 ± 10.7 years in the present study population. R values (p value) for the 4 time periods were 0.50 (0.002), 0.33 (0.035), 0.42 (0.007), and 0.48 (0.002). Bias and 95% limits of agreement in L/min were -0.11 (-2.40 to 2.18), 0.04 (-2.57 to 2.65), -0.06 (-2.86 to 2.74), and 0.02 (-2.42 to 2.45). Percent errors of the 4 time periods were 51%, 53%, 50%, and 48%. CONCLUSIONS: ECOM did not adequately agree with TD in patients undergoing cardiac surgery.

The pocket echocardiograph: validation and feasibility.

BACKGROUND: A new, miniaturized ultrasound device, the pocket echocardiograph (PE), is highly portable and can be carried inside a lab-coat pocket. Studies of this device are limited and have not examined the use by novice echocardiographers. We hypothesize that a novice echocardiographer can use PE to produce interpretable cardiac images, and that both novice and expert echocardiographers can use PE to accurately quantify ejection fraction. METHODS: Unselected subjects (n = 40) in an echocardiography laboratory underwent blinded formal transthoracic echocardiography (TTE) and PE (Acuson P10, Siemens, Mountain View, CA, USA). A cardiology fellow with 2 months of echocardiography training acquired PE images. The fellow and an experienced echocardiographer interpreted the PE studies offline in a blinded fashion. To assess adequacy, studies were graded as technically adequate, limited, or inadequate. A visual estimation of ejection fraction was made. Comparisons were made to the formal reported TTE. RESULTS: Subjects were heterogeneous, 43% male; age 64 ± 17 years, and ejection fraction 52.4%± 12.3%. All PE studies were interpretable, and the vast majority of PE and TTE images were considered technically adequate (77.5% and 85% respectively; P = 0.32). Ejection fraction showed a good correlation, bias, and limits of agreement for the fellow's interpretation (r = 0.78, -5.9%, ±16.6%) with stronger association for the experienced echocardiographer (r = 0.88, -0.8%, ±11.4%). CONCLUSION: Novice echocardiographers using the PE can produce adequate quality images. Both expert and novice echocardiographers can use PE to quantify ejection fraction over a broad range of patients. The device's low cost and portability may greatly expand the availability of bedside echocardiography for routine or urgent cardiovascular assessment.

Selective intracranial magnification angiography of the rabbit: basic techniques and anatomy.

Development of new therapies for stroke requires animal models with well-defined intracranial vasculature. The rabbit as a small animal model has many desirable traits; however, a modern atlas of rabbit angiographic anatomy is not readily available. Improved digital subtraction magnification angiography and superselective small-catheter techniques now allow excellent anatomical definition. Angiographic techniques include selection of the internal carotid artery and subselection with microcatheters that can progress to branches of the circle of Willis and provide high-resolution cerebral angiography. The authors present an overview of current techniques and illustrations of the angiography of cerebral vessels.