Adrenaline dosage and buffers in cardiac arrest.
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Aged↗
Biomedical subjects
A A Adgey
Publications and source records attributed to A A Adgey.
An overview of the results of clinical trials with glycoprotein IIb/IIIa inhibitors.
The era of platelet glycoprotein (GP) IIb/IIIa receptor inhibition in cardiology was inaugurated in 1994 with the publication of the Evaluation of 7E3 for the Prevention of Ischemic Complications (EPIC) trial results. EPIC demonstrated that the GP IIb/IIIa blocker abciximab, administered as a bolus and 12-hour infusion, afforded protection against ischemic complications in high-risk patients undergoing angioplasty and atherectomy, including those with unstable angina or evolving myocardial infarction (MI). A significant reduction in the incidence of death, acute MI, or revascularization was apparent at 30 days and also sustained at 6-month and 3-year follow-up. The subsequent Evaluation in PTCA to Improve Long-Term Outcome with Abciximab GP IIb/IIIa Blockade (EPILOG) study extended these findings to the full spectrum of coronary intervention patients, confirming that abciximab provided similar benefits in low-risk patients as well. The EPILOG trial also proved that any excess bleeding risk associated with potent antiplatelet therapy could be brought down to placebo levels through the use of a low-dose, weight-adjusted heparin regimen, early vascular sheath removal, and elimination of routine postprocedural heparinization. The potential for an advantage of GP IIb/IIIa blockade in patients with refractory unstable angina/non-Q-wave MI was demonstrated in the c7E3 Fab Antiplatelet Therapy in Unstable Refractory Angina (CAPTURE) trial, which showed that a 24-hour preprocedural abciximab infusion effectively stabilized these patients, thereby enhancing the safety of intervention and reducing the 30-day incidence of ischemic events. A similar pattern of benefit has emerged from clinical trials of such other GP IIb/IIIa inhibitors as eptifibatide, lamifiban, and tirofiban. Trials are currently underway to clarify the benefits of GP IIb/IIIa blockers in patients undergoing stenting and as an adjunct to thrombolytic therapy or primary angioplasty in patients with acute MI (ST-segment elevation).
Abciximab↗
Safe use of platelet GP IIb/IIIa inhibitors.
The platelet membrane glycoprotein IIb/IIIa receptor inhibitor abciximab is used for the treatment of patients undergoing high-risk percutaneous coronary interventions and is used in approximately one third of coronary interventions in the United States and a growing number of procedures in Europe. Recent clinical trials have shown that this potent antiplatelet agent significantly reduces the incidence of death and nonfatal myocardial infarction and the need for revascularization. With expanding experience since the commercial release of abciximab in February 1995, several strategies to enhance the safety of abciximab have emerged. In particular, new data confirm that the risk of bleeding--identified as a concern in the original EPIC trial--can be substantially reduced through the use of low-dose adjunctive heparin, early sheath removal, and fastidious postprocedure vascular access site care. Other recommendations for enhancing the safety of potent antiplatelet agents in a variety of clinical situations are provided. The following article reflects insights regarding the safety of glycoprotein IIb/IIIa inhibitors expressed by a group of international experts convened in Davos, Switzerland, February 16, 1997. This report attempts to review clinical progress to date, formulate recommendations, and map out potentially fruitful lines of inquiry for future investigation.
Abciximab↗
Randomized, double-blind comparison of hirulog versus heparin in patients receiving streptokinase and aspirin for acute myocardial infarction (HERO). Hirulog Early Reperfusion/Occlusion (HERO) Trial Investigators.
BACKGROUND: Thrombolytic therapy improves survival after myocardial infarction through reperfusion of the infarct-related artery. Thrombin generated during thrombolytic administration may reduce the efficacy of thrombolysis. A direct thrombin inhibitor may improve early patency rates. METHODS AND RESULTS: Four hundred twelve patients presenting within 12 hours with ST-segment elevation were given aspirin and streptokinase and randomized in a double-blind manner to receive up to 60 hours of either heparin (5000 U bolus followed by 1000 to 1200 U/h), low-dose hirulog (0.125 mg/kg bolus followed by 0.25 mg x kg(-1) x h(-1) for 12 hours then 0.125 mg x kg(-1) x h(-1)), or high-dose hirulog (0.25 mg/kg bolus followed by 0.5 mg x kg(-1) x h(-1) for 12 hours then 0.25 mg x kg(-1) x h(-1)). The primary outcome was Thrombolysis In Myocardial Infarction trial (TIMI) grade 3 flow of the infarct-related artery at 90 to 120 minutes. TIMI 3 flow was 35% (95% CI, 28% to 44%) with heparin, 46% (95% CI, 38% to 55%) with low-dose hirulog, and 48% (95% CI, 40% to 57%) with high-dose hirulog (heparin versus hirulog, P=.023; heparin versus high-dose hirulog, P=.03). At 48 hours, reocclusion had occurred in 7% of heparin, 5% of low-dose hirulog, and 1% of high-dose hirulog patients (P=NS). By 35 days, death, cardiogenic shock, or reinfarction had occurred in 25 heparin (17.9%), 19 low-dose hirulog (14%), and 17 high-dose hirulog patients (12.5%) (P=NS). Two strokes occurred with heparin, none with low-dose hirulog, and two with high-dose hirulog. Major bleeding (40% from the groin site) occurred in 28% of heparin, 14% of low-dose hirulog, and 19% of high-dose hirulog patients (heparin versus low-dose hirulog, P<.01). CONCLUSIONS: Hirulog was more effective than heparin in producing early patency in patients treated with aspirin and streptokinase without increasing the risk of major bleeding. Direct thrombin inhibition may improve clinical outcome.
Analysis of Variance↗
Ventricular pacing with a novel gastroesophageal electrode: a comparison with external pacing.
Temporary endocardial pacing is a technically demanding invasive procedure requiring sterile precautions and access to fluoroscopy. External (transcutaneous) pacing requires high current for capture and is poorly tolerated in the conscious patient. An esothoracic pacing system has been developed capable of reliable ventricular capture. The flexible gastroesophageal electrode is passed into the stomach. The distal 6 cm is angled to 90 degrees with an internal pulley system, positioning the tip of the gastroesophageal electrode in the fundus of the stomach. Ventricular pacing is performed with a spherical electrode (cathode) mounted on the gastroesophageal electrode tip in conjunction with a chest pad (anode) positioned medial to the cardiac apex. Of 91 subjects in which esothoracic pacing was attempted, 86 (94.5%) demonstrated successful ventricular capture at the maximum pulse duration used (40 msec). Threshold current for ventricular capture ranged from 22.5 +/- 8.1 mA at a pulse duration of 40 msec to 29.9 +/- 8.6 mA at a pulse duration of 10 msec. Esothoracic pacing was compared with external pacing in a subgroup (n = 30) of patients. Ventricular capture with the gastroesophageal electrode was more common when compared with the external approach (27 [90%] of 30 vs 13 [43.3%] of 30, p < 0.001). In those subjects in whom ventricular capture was obtained with both methods, threshold current for capture was significantly lower with the esothoracic approach. This gastroesophageal electrode may be useful in the emergency management of acute bradyarrhythmias.
Adult↗
A gastroesophageal electrode for atrial and ventricular pacing.
Temporary transvenous cardiac pacing requires technical expertise and access to fluoroscopy. We have developed a gastroesophageal electrode capable of atrial and ventricular pacing. The flexible polythene gastroesophageal electrode is passed into the stomach under light sedation. Five ring electrodes, now positioned in the lower esophagus, are used for atrial pacing. A point source (cathode) on the distal tip of the electrode, now positioned in the gastric fundus, is used for ventricular pacing. Two configurations of atrial and ventricular pacing were compared: unipolar and bipolar. During unipolar ventricular pacing the indifferent electrode (anode) was a high impedance chest pad. For bipolar ventricular pacing the indifferent electrode was a ring electrodes placed 2 cm proximal to the tip. Unipolar atrial pacing was performed with 1 of 5 proximal ring electrodes acting as cathode ("cathodic") or as anode ("anodic") in conjunction with a chest pad. Bipolar atrial pacing was performed using combinations of 2 of 5 ring electrodes. Atrial capture was obtained in all 55 subjects attempted. When all electrode combinations were compared, atrial capture was significantly more frequent using the bipolar approach (153/210 bipolar, 65/210 unipolar; t = 7.37, P < 0.001). For unipolar atrial pacing, cathodic stimulation (from esophagus) was more successful than anodic stimulation (cathodic 62/105, anodic 20/105; t = 5.81, P < 0.001). In 43 subjects attempted unipolar ventricular pacing resulted in a higher frequency of capture than the bipolar approach (unipolar 41/43 (95.3%), bipolar 19/43 (44.2%); P < 0.001). In conclusion, atrial pacing was optimal using pairs of ring electrodes ("bipolar") while ventricular pacing was optimal using the distal electrode tip (cathode) in conjunction with a chest pad electrode ("unipolar"). This gastroesophageal electrode may be useful in the emergency management of acute bradyarrhythmias and for elective electrophysiological studies.
Adult↗
Rounded biphasic waveform reduces energy requirements for transvenous catheter cardioversion of atrial fibrillation and flutter.
We postulated that reducing peak leading edge shock voltage and its rate of rise (waveform rounding) would reduce energy requirements for cardioversion of AF and AFl, and may therefore reduce patient discomfort. Transvenous defibrillating catheters (In-Control Inc.) were placed in the RAA (active fixation) and the CS of six anesthetized sheep. AF or AFl was induced by electrical stimulation (100 Hz, 2 V; Grass stimulator). A standard trapezoidal biphasic (S) waveform (3-ms duration each phase) was compared with a similar waveform that had the first phase rounded (R). Cardioversion was attempted after 30 seconds of arrhythmia, using a Ventritex HVS-O2 defibrillator modified to allow waveform rounding. Each waveform was randomly tested several times at 100-, 150-, and 200-V leading edges, and percentage cardioversion success calculated. Shock energy was calculated from delivered current and voltage using Flukeview (Fluke, Inc.) software. At 100-V leading edge R (64% success) and S (59%), shocks were similarly efficacious (P = 0.37). However, R delivered less current, voltage, and energy than the comparable S shock (means 1.30 A, 65.0 V, 0.33 J R vs 1.92 A, 94.2 V, 0.47 J S; P = 0.0001). Both waveforms were equally successful at 150 V (88% vs 100%; P = NS) and 200 V (100% vs 100%), but again R delivered less current, voltage, and energy (2.05 A, 102.5 V, 0.82 J R vs 2.78 A, 142.3 V, 1.11 J S at 150 V; 2.76 A, 141.2 V, 1.58 J R vs 3.77 A, 189.4 V, 2.03 J S at 200 V; both P = 0.0001). No arrhythmic or other complications occurred in the 174 shocks delivered. Waveform rounding reduces delivered peak voltage, current, and energy without reducing defibrillation efficacy. To determine if these changes are associated with a reduction in discomfort, patients with AF are currently being cardioverted with these waveforms during electrophysiological studies.
Animals↗
Dangers of European resuscitation guidelines.
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Amiodarone↗
Pneumococcal pericarditis--out of sight, out of mind?
Pneumococcal pericarditis has been an uncommon condition in recent years. This report describes the case of a 57-year-old woman with sarcoidosis who presented with cardiac tamponade due to pneumococcal pericarditis. She responded to pericardiocentesis and intravenous antibiotic therapy. At 4-month review, she remains well.
Anti-Bacterial Agents↗
Out-of-hospital resuscitation: room for improvement.
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Cardiopulmonary Resuscitation↗
Effects of blockade of fast and slow inward current channels on ventricular fibrillation in the pig heart.
OBJECTIVE: To determine the contribution of fast and slow inward channels to the electrocardiogram (ECG) of ventricular fibrillation. METHODS: Ventricular fibrillation was induced by endocardial electrical stimulation in pigs anaesthetised with pentobarbitone sodium (30 mg/kg intravenously). ECGs simultaneously recorded from the body surface (lead II) and from the endocardium were studied by power spectrum analysis (0-40 Hz). RESULTS: The mean (SEM) dominant frequency of fibrillation (9.0 (1.1) Hz in lead II at 0-40 s) did not change significantly with time in pigs given intravenous saline. However, the dominant frequency was significantly reduced by intravenous pretreatment with the class I antiarrhythmic drugs, lignocaine (3 mg/kg, 6.5 (0.5) Hz; 10 mg/kg, 4.2 (0.6) Hz), mexiletine (3 mg/kg, 6.2 (0.4) Hz; 10 mg/kg, 5.5 (0.4) Hz), and disopyramide (2.5 mg/kg, 5.4 (0.6) Hz). After flecainide (3 mg/kg, 6.9 (0.5) Hz) the reduction in frequency was not significant. Similar data were obtained with endocardial recordings. In contrast pre-treatment with verapamil (0.2 mg/kg, 11.7 (0.8) Hz; and 1.0 mg/kg, 12.9 (1.6) Hz) produced a significantly higher dominant frequency of fibrillation than saline and widened the bandwidth of frequencies around the dominant frequency. CONCLUSIONS: These results indicate that voltage-dependent sodium channel currents contribute to the rapid frequencies of ventricular fibrillation. Blockade of L-type inward calcium channel activity increases the fibrillation frequency and fractionates the frequencies of the fibrillation wavefronts.
Animals↗
Sudden cardiac death and substance abuse.
There has been a steady increase in the number of deaths occurring from volatile substance abuse per year. The majority of deaths are in males, the peak age group being 15-19 years. Fuel gases i.e. cigarette lighter refills (butane), propane and gasoline and other solvents such as typewriter correction fluid, dry-cleaning fluids (trichloroethane) and fire extinguishers (bromochlorodifluoromethane) are responsible for approximately 60% of these deaths. Volatile substances sensitise the heart to circulating catecholamines, such that sudden alarm or exercise may precipitate sudden death. The main mechanism of cardiac arrest is a cardiac arrhythmia, but anoxia, respiratory depression and vagal stimulation along with aspiration of vomit or trauma may be contributing factors to the sudden death. In addition, particularly butane gas inhalation may be associated with severe laryngeal oedema and laryngospasm. Resuscitation from sudden death associated with volatile substance abuse is rare, since the majority of deaths are unwitnessed. It is suggested that cardiac arrhythmias should be treated conventionally. Sympathomimetic drugs should be avoided. Early during the resuscitation process, beta-adrenergic blocking agents should be administered to protect the catecholamine-sensitised heart. Early intubation in the management of the cardiac arrest should be avoided, if the inhalational agent is known to be associated with laryngospasm.(ABSTRACT TRUNCATED AT 250 WORDS)
Acidosis↗
Body surface ECG potential maps in acute myocardial infarction.
An algorithm for the early detection of acute myocardial infarction (MI) using body surface electrocardiographic potential mapping has been developed. The mapping system consists of a 64-hydrogel electrode harness applied rapidly to the anterior chest, from which electrocardiographic signals are stored on a memory card and processed by computer. At each of the 64 points, QRS and ST-T isointegrals and 10 other features of the QRST segment are measured. Using these measurements, new variables are derived that express the shape of the three-dimensional geometric surface of the map. The isointegrals, features, and shape variables are used in a variety of techniques to discriminate between MI and control subjects. Maps were recorded from 69 patients at initial presentation of chest pain suggestive of acute MI and from 80 healthy control subjects. Using a multiple logistic regression technique, 14 variables were identified that correctly classified 79 of the 80 control subjects (specificity, 98.8%) and 65 of the 69 MI patients (sensitivity, 94.2%). The algorithm based on these 14 variables was applied prospectively to maps recorded on a further 48 control subjects and 59 patients with acute MI. Of the MI patients, 31 had inferior, 13 inferoposterior, 10 anterior, 2 posterior, 1 lateral, 1 inferior with right bundle branch block, and 1 anterior non Q wave MI. The algorithm correctly classified all 48 control subjects (specificity, 100%) and 57 of the 59 MI patients (sensitivity, 96.6%). Marked differences in the three-dimensional geometric map surfaces between the control subjects and MI patients were demonstrated. Variables derived from these surfaces form the basis of an algorithm with a high sensitivity and specificity for the automated detection of acute MI. The design of adaptive algorithms and their application to patients with chest pain and atypical electrocardiographic changes, particularly ST depression, may lead to the earlier detection of MI and greater numbers of patients receiving thrombolytic therapy.
Adolescent↗
An esophageal and gastric approach to ventricular pacing.
Using a unipolar esothoracic pacing system (where current passes from a point source positioned in the distal esophagus to a chest wall pad) and pulse duration of 50 msec, satisfactory 1:1 ventricular capture was obtained in 57 (86%) of 66 patients, with a mean threshold current of 27.7 mA at an optimal depth of 40.3 cm from the lower lip. When the unipolar esothoracic and bipolar transesophageal ventricular pacing systems were compared, the bipolar system was associated with a lower success rate and higher threshold current. When unipolar esothoracic pacing and gastrothoracic pacing (where current passes from a point source positioned in the stomach to a chest wall pad) were compared in 23 patients with bradyarrhythmia, ventricular capture was achieved using gastrothoracic pacing in 22 patients (96%) and esothoracic pacing in 21 (91%): gastrothoracic pacing required less current (16.0 mA +/- SD 7.2 vs 25.8 mA +/- SD 8.6). Optimal ventricular capture occurred using a unipolar gastrothoracic pacing electrode inserted to an average depth of 44.3 cm together with a high impedance chest pad (250 omega) placed in the fourth interspace at the left sternal edge, with 50-msec current pulses and a mean threshold of 16.0 mA. Thus, using a gastroesophageal electrode system, ventricular pacing can be achieved successfully, and the availability of such a system could play a major role in resuscitation of patients from severe bradyarrhythmias.
Bradycardia↗
Esophageal countershock: anthropometric determinants of impedance.
OBJECTIVE: To examine the use of a novel esophageal electrode system for countershock of atrial and ventricular tachyarrhythmias, with particular regard to the measurement of transesophageal and transthoracic impedances and their association with anthropometric variables. METHODS: Transesophageal cardioversion was attempted during 131 episodes of arrhythmia in 105 patients (including 109 episodes of atrial fibrillation). The esophageal system also used in 29 patients undergoing electrophysiologic studies for investigation of ventricular tachyarrhythmias. Transesophageal and transthoracic impedances were estimated during passage of a high-frequency, low-amplitude current between the respective electrodes. Impedance estimates were associated with anthropometric measurements using linear regression (least-squares method). RESULTS: In the group of patients undergoing attempted transesophageal cardioversion, the mean estimated transesophageal impedance of 52.6 +/- 11.7 omega was significantly lower than the mean estimated transthoracic impedance of 63.1 +/- 16.4 omega (n = 104, p < 0.01). For all the patients, transesophageal impedance was associated with weight, body mass index, and chest circumference (all r > or = 0.65, p < 0.01). Transthoracic impedance was associated with the same factors (all r > or = 0.55, p < 0.01). CONCLUSION: This esophageal electrode system results in lower impedance values for countershock between the esophagus and the cutaneous cardiac apex in comparison with standard transthoracic cutaneous electrode placement. Both techniques are dependent on anthropometric factors.
Adult↗
Systemic lupus erythematosus presenting as effuso-constrictive pericarditis.
We describe a 62-year-old woman in whom systemic lupus erythematosus presented as life-threatening effuso-constrictive pericarditis. Surgical drainage of the pericardium was required and the patient made a satisfactory recovery. At six-months follow-up, while taking hydroxychloroquine and a non-steroidal anti-inflammatory agent, she remains well.
Anti-Inflammatory Agents, Non-Steroidal↗
Asystolic arrest as a presentation of sarcoidosis.
A 41-year-old man who presented with a history of sudden loss of consciousness suffered two further episodes during which asystole was documented. Subsequent investigations included exercise stress testing, thallium scintigraphy, electrophysiological studies, CT-scan of chest, Kveim test and a gallium-67 scan, which led to a presumptive diagnosis of averted sudden death as a first presentation of sarcoidosis with primary cardiac involvement.
Adult↗
Use of the gastro-oesophageal route for the rapid establishment of ventricular pacing.
A novel approach to emergency ventricular pacing has been developed using a gastro-esophageal electrode. The polythene electrode was passed into the stomach, after which the electrode tip was positioned in the gastric fundus. Ventricular pacing was performed using a cathode mounted on the electrode tip; the indifferent electrode (anode) was either a chest pad or a proximal ring electrode. Ventricular capture was easily achieved in three emergency cases of severe bradyarrhythmia.
Adult↗