Risk of bleeding in patients undergoing pulmonary procedures on antiplatelet or anticoagulants: A systematic review.

As many as 25% of all patients undergoing invasive pulmonary procedures are receiving at least one antiplatelet or anticoagulant agent. For those undergoing elective procedures, the decision-making process is uncomplicated and the procedure may be postponed until the antiplatelet or anticoagulant agent may be safely held. However, many invasive pulmonary procedures are semi-elective or emergent in nature in which case a risk-benefit calculation and discussion occur between the provider and patient or surrogate decision-maker. Therefore, it is critical for providers to have an awareness of the risk of bleeding complications with different pulmonary procedures on various antiplatelet and anticoagulant agents. This systematic review summarizes the bleeding complications associated with different pulmonary procedures in patients on various antiplatelet or anticoagulant agents in the literature and reveals a paucity of high-quality evidence across a wide spectrum of pulmonary procedures and antiplatelet or anticoagulant agents. The results of this review can help inform providers of the bleeding risk in these patients to aid in the shared decision-making process and risk vs benefit discussion.

Optimal imaging protocol for measuring dynamic expiratory collapse of the central airways.

AIM: To compare measurements of expiratory collapse obtained using multidetector computed tomography (MDCT) of the central airways on routine axial and multiplanar reformatted (MPR) images. MATERIALS AND METHODS: Fifty volunteers with normal pulmonary function and no smoking history were imaged using a 64 MDCT system (40 mAs, 120 kVp, 0.625 mm collimation) with spirometric monitoring at end-inspiration and during forced expiration. Measurements of the trachea, right main (RMB) and left main bronchus (LMB) were obtained on axial and MPR images. Inspiratory and dynamic-expiratory cross-sectional area (CSA) measurements were used to calculate the mean percentage expiratory collapse (%Collapse). A paired t-test was used to assess within-subject differences and a Bland-Altman plot was used to assess agreement between the methods. RESULTS: Among 24 men and 26 women (mean age±standard deviation 50±15 years), CSA values were significantly greater on axial than MPR images (all p<0.001); however, the mean difference in %Collapse values for axial versus MPR were small: trachea ≈1% (55 ±19 versus 56±18, p=0.338); LMB identical (60±20 versus 60±17 p=0.856); and, RMB 4% (62 ±19 versus 66±19 p<0.001). On average, creation of MPR required 12 minutes of additional time per case (range=10-15 min). CONCLUSION: Differences in mean %Collapse for axial versus MPR images were small and unlikely to influence clinical management. This finding suggests that MPR may not be indicated for routine assessment of central airway collapse.

A shared regulatory perspective on deferral from blood donation of men who have sex with men (MSM).

National Regulatory Authorities (NRAs) establish deferral criteria for donors with risk factors for transfusion transmissible infections (TTI). In most jurisdictions, epidemiological data show that men who have sex with men (MSM) have a significantly higher rate of TTI than the general population. Nevertheless, changes from an indefinite donor deferral for MSM have been considered in many countries in response to concerns over a perceived discrimination and questioning of the scientific need. Changes to MSM donor deferral criteria should be based on sound scientific evidence. Safety of transfusion recipients should be the first priority, and stakeholder input should be sought.

Sterilization by gamma radiation of antibiotic impregnated polymethylmethacrylate and plaster of Paris beads. A pilot study.

INTRODUCTION: Ethylene oxide is currently recommended for sterilization of antibiotic impregnated beads; however this method carries health risks to personnel and is becoming less available. OBJECTIVE: To perform a pilot study of the effect of radiation for sterilization of polymethylmethacrylate (PMMA) and plaster of Paris (POP) beads impregnated with amikacin, enrofloxacin, and ceftiofur. HYPOTHESIS: Radiation would effectively sterilize the beads without affecting the efficacy of the antibiotic. MATERIALS AND METHODS: Beads of PMMA and POP were prepared in a clean but non-sterile manner with one of the three antibiotics (amikacin, enrofloxacin, ceftiofur) or no antibiotic. Beads were then exposed to radiation for a total dose of 0 kiloGray (kGy), 10 kGy and 25 kGy. Beads were incubated on Mueller-Hinton agar plates seeded with Escherichia coli, Staphylococcus aureus or Pseudomonas aeruginosa for 24 hours or cultured in brain-heart infusion broth for 48 hours. Zones of inhibition were measured on the agar plates and statistics were performed on the diameters of the zones of inhibition using an analysis of variance. RESULTS: There were no differences in the diameters of inhibition for all levels of radiation for all PMMA beads. The same was true with POP beads with the exception of enrofloxacin which had a significantly decreased zone of inhibition with increased levels of radiation, though the clinical significance of this finding was not assessed. Only beads without antibiotics and not exposed to radiation had bacterial growth. CLINICAL SIGNIFICANCE: Radiation may be an effective method of sterilization for antibiotic impregnated beads.

Optimal transseptal puncture location for robot-assisted left atrial catheter ablation.

BACKGROUND: The preferred method of treatment for atrial fibrillation (AF) is by catheter ablation, in which a catheter is guided into the left atrium through a transseptal puncture. However, the transseptal puncture constrains the catheter, thereby limiting its manoeuvrability and increasing the difficulty in reaching various locations in the left atrium. In this paper, we address the problem of choosing the optimal transseptal puncture location for performing cardiac ablation to obtain maximum manoeuvrability of the catheter. METHODS: We have employed an optimization algorithm to maximize the global isotropy index (GII) to evaluate the optimal transseptal puncture location. As part of this algorithm, a novel kinematic model for the catheter has been developed, based on a continuum robot model. Pre-operative MR/CT images of the heart are segmented using the open source image-guided therapy software, 3D Slicer, to obtain models of the left atrium and septal wall. These models are input to the optimization algorithm to evaluate the optimal transseptal puncture location. RESULTS: The continuum robot model accurately describes the kinematics of the catheter. Simulation and experimental results for the optimal transseptal puncture location are presented in this paper. The optimization algorithm generates discrete points on the septal wall for which the dexterity of the catheter in the left atrium is maximum, corresponding to a GII of 0.4362. CONCLUSION: We have developed an optimization algorithm based on the GII to evaluate the optimal position of the transseptal puncture for left atrial cardiac ablation.

Predicting atelectasis by assessment of collateral ventilation prior to endobronchial lung volume reduction: a feasibility study.

BACKGROUND: The advent of endoscopic lung volume reduction (ELVR), especially relying on valve technology to achieve atelectasis, has aroused new interest in the assessment of collateral ventilation, which has been implicated in ELVR failures. We are reporting on the use of a catheter-based device that measures airway pressures and flows, and calculates airway resistance in vivo. OBJECTIVES: To assess the safety of this catheter-based system and the feasibility of obtaining measurements predictive of atelectasis after ELVR. METHODS: Patients undergoing ELVR were prospectively included in this double-blind cohort study. Each lobe targeted for ELVR was blocked with a catheter system (Chartis® System; Pulmonx, Inc., Redwood, Calif., USA); pressures and flows were assessed continuously. The primary endpoints were to evaluate the safety and feasibility; the secondary endpoint was to assess whether there was a relationship between the measurements and the incidence of atelectasis following ELVR. RESULTS: From June 2008 to November 2008, 25 patients were included in the study. All procedures could be performed without any complications. Due to pneumothorax in 1 case and inability to assess the catheter-based measurements in 4 cases, the final analysis included 20 patients. Atelectasis occurred in 8 out of 20 cases following implantation. In 18 patients (90%), the resistance measurements correlated with the postimplantation atelectasis visualized on a chest X-ray; in 2 patients (10%), a mismatch was detected. CONCLUSIONS: Resistance measurements were safely and successfully achieved. In 90% of the analyzable cases, the resistance measurements correlated with the occurrence of atelectasis after ELVR. The clinical impact of these findings will need to be evaluated in subsequent trials.

Use of tunnelled catheters for malignant pleural effusions in patients fit for pleurodesis.

The aim of the present study was to examine the effectiveness of tunnelled pleural catheters (TPC) in patients with malignant pleural effusions who would otherwise be candidates for pleurodesis. Patients were selected from a previously reported database of 250 TPC insertions. The study group was selected based on lung re-expansion and survival as a surrogate maker of eligibility for pleurodesis procedure, as defined by survival of > or =90 days and lung re-expansion > or =80% post-drainage on a standard chest radiograph 2 weeks post TPC placement. There were 109 procedures in 97 patients that met the entry criteria. Spontaneous pleurodesis (SP) was achieved following 70% of procedures and correlated with symptom control. The mean time to SP was 90 days. There was no need for a repeat procedure in 87% of cases overall and in 92% of patients experiencing SP. There were few complications and no procedure-related deaths. Tunnelled pleural catheters are an effective way of controlling malignant pleural effusions when used as first-line treatment in patients who appear to be candidates for pleurodesis procedures.

Hot biopsy forceps in the diagnosis of endobronchial lesions.

Electrocoagulation bronchoscopy biopsy forceps may prevent bleeding, but could also impair the quality of the specimens obtained. Patients with endobronchial lesions during bronchoscopy underwent six endobronchial biopsies each with a hot biopsy forceps, alternating between with electrocoagulation ("hot") and without ("cold"). Bleeding was quantified on a scale of 1-4, with 1 being no bleeding. The generator was set on "soft coagulation" mode, with power settings of 40, 60, 80 and 100 W for each group of 10 patients in a sequential fashion. Clinical pathology results were recorded before samples were reviewed by a second, blinded, pulmonary pathologist. A total of 39 patients with 40 endobronchial lesions had six biopsies performed (one patient had only four samples taken), giving a total of 238 biopsy samples. Concordance between hot and cold samples was 92.5% for the clinical pathologist and 87% for the blinded pathologist. Paired analysis suggested lower average bleeding score with the use of hot forceps. Overall bleeding rates for cold and hot biopsies, respectively, were as follows: grade 1: 30.3 and 41.2%; grade 2: 62.2 and 49.6%; grade 3: 7.6 and 9.2%; and grade 4: 0 and 0%. In conclusion, the use of hot biopsy forceps for endobronchial biopsy does not appear to have a negative impact on the pathological samples. Hot biopsy forceps showed a statistically significant reduction in bleeding score, which is unlikely to be of clinical significance.

Relationship between serum potassium concentration and risk of recurrent ventricular tachycardia or ventricular fibrillation.

INTRODUCTION: Electrolyte abnormalities are considered a correctable cause of a life-threatening ventricular arrhythmia according to American Heart Association/American College of Cardiology Practice Guidelines, and ventricular tachycardia or ventricular fibrillation in the setting of an electrolyte abnormality is considered a class III indication for defibrillator implantation. However, there are little data to support this recommendation. The purpose of this study was to determine the risk of a recurrent sustained ventricular arrhythmia in patients with a low serum potassium concentration at the time of an initial episode of a sustained ventricular arrhythmia. METHODS AND RESULTS: One hundred sixty-nine consecutive patients who presented with a sustained ventricular arrhythmia and a serum potassium concentration determined on the day of the arrhythmia underwent defibrillator implantation. All patients had structural heart disease and left ventricular ejection fraction of 0.32+/-0.15. On the day of the index arrhythmia, 30% of the patients had a serum potassium concentration <3.5 or >5.0 mEq/L, including 7% who had a serum potassium concentration <3.0 or >6.0 mEq/L. For the entire cohort of patients, freedom from a recurrent sustained ventricular arrhythmia was 18% at 5 years and was not significantly different among patients with a serum potassium concentration <3.5 mEq/L (23%), between 3.5 and 5.0 mEq/L (16%), and >5.0 mEq/L (5%; P = 0.1). CONCLUSION: The results of the present study suggest that patients with structural heart disease and an abnormal serum potassium concentration at the time of an initial episode of sustained ventricular tachycardia or ventricular fibrillation are at high risk for a recurrent ventricular arrhythmia; therefore, implantable defibrillator therapy may be reasonable.

Differentiation of atypical atrioventricular node re-entrant tachycardia from orthodromic reciprocating tachycardia using a septal accessory pathway by the response to ventricular pacing.

OBJECTIVES: The purpose of this study was to determine whether the response to ventricular pacing during tachycardia is useful for differentiating atypical atrioventricular node re-entrant tachycardia (AVNRT) from orthodromic reciprocating tachycardia (ORT) using a septal accessory pathway. BACKGROUND: Although it is usually possible to differentiate atypical AVNRT from ORT using a septal accessory pathway, a definitive diagnosis is occasionally elusive. METHODS: In 30 patients with atypical AVNRT and 44 patients with ORT using a septal accessory pathway, the right ventricle was paced at a cycle length 10 to 40 ms shorter than the tachycardia cycle length (TCL). The ventriculo-atrial (VA) interval and TCL were measured just before pacing. The interval between the last pacing stimulus and the last entrained atrial depolarization (stimulus-atrial [S-A] interval) and the post-pacing interval (PPI) at the right ventricular apex were measured on cessation of ventricular pacing. RESULTS: All 30 patients with atypical AVNRT and none of the 44 patients with ORT using a septal accessory pathway had an S-A-VA interval >85 ms and PPI-TCL >115 ms. CONCLUSIONS: The S-A-VA interval and PPI-TCL are useful in distinguishing atypical AVNRT from ORT using a septal accessory pathway.

Should an abnormal serum potassium concentration be considered a correctable cause of cardiac arrest?

According to American Heart Association/American College of Cardiology Practice Guidelines, electrolyte abnormalities, including abnormal serum potassium concentrations, are considered a correctable cause of a life-threatening ventricular arrhythmia. Ventricular defibrillator therapy in this situation is a class III indication, and thought to be ineffective and perhaps harmful, although there are minimal data to support this recommendation. The steady-state serum potassium concentration frequently changes during a cardiac arrest. Additionally, the vast majority of cardiac arrest patients have structural heart disease and are commonly treated with a variety of medications that can alter the serum potassium concentration. In the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial, patients with a correctable cause of an electrolyte imbalance were excluded from study participation but were followed in the AVID registry. Similar outcomes were observed among patients in the AVID registry and the main trial. Spironolactone therapy in patients with congestive heart failure decreases all-cause mortality and sudden and nonsudden cardiac death. In a preliminary study of 169 patients with an episode of a sustained ventricular arrhythmia treated with an implantable defibrillator, freedom from appropriate defibrillator therapy was 18% after five years. The probability of appropriate defibrillator therapy was independent of the initial serum potassium concentration. For these reasons, our current clinical practice is to use an implantable defibrillator to treat an initial episode of sustained ventricular tachycardia or ventricular fibrillation that occurs in a patient with structural heart disease and an abnormal serum potassium concentration.

Noninvasive diagnosis of a wide QRS complex tachycardia mechanism by programmed atrial and ventricular stimulation using a dual chamber defibrillator.

Stored atrial and ventricular electrograms retrieved from dual chamber implantable defibrillators facilitate the diagnosis of arrhythmias. This case also illustrates the usefulness of programmed atrial and ventricular stimulation for noninvasive rhythm diagnosis in patients with a wide QRS tachycardia and an implantable defibrillator.

Electrogram polarity and cavotricuspid isthmus block during ablation of typical atrial flutter.

INTRODUCTION: The atrial activation sequence around the tricuspid annulus has been used to assess whether complete block has been achieved across the cavotricuspid isthmus during radiofrequency ablation of typical atrial flutter. However, sometimes the atrial activation sequence does not clearly establish the presence or absence of complete block. The purpose of this study was to determine whether a change in the polarity of atrial electrograms recorded near the ablation line is an accurate indicator of complete isthmus block. METHODS AND RESULTS: Radiofrequency ablation was performed in 34 men and 10 women (age 60 +/- 13 years [mean +/- SD]) with isthmus-dependent, counterclockwise atrial flutter. Electrograms were recorded around the tricuspid annulus using a duodecapolar halo catheter. Electrograms recorded from two distal electrode pairs (E1 and E2) positioned just anterior to the ablation line were analyzed during atrial flutter and during coronary sinus pacing, before and after ablation. Complete isthmus block was verified by the presence of widely split double electrograms along the entire ablation line. Complete bidirectional isthmus block was achieved in 39 (89%) of 44 patients. Before ablation, the initial polarity of E1 and E2 was predominantly negative during atrial flutter and predominantly positive during coronary sinus pacing. During incomplete isthmus block, the electrogram polarity became reversed either only at E2, or at neither E1 nor E2. In every patient, the polarity of E1 and E2 became negative during coronary sinus pacing only after complete isthmus block was achieved. In 4 patients (10%), the atrial activation sequence recorded with the halo catheter was consistent with complete isthmus block, but the presence of incomplete block was accurately detected by inspection of the polarity of E1 and E2. CONCLUSION: Reversal of polarity in bipolar electrograms recorded just anterior to the line of isthmus block during coronary sinus pacing after ablation of atrial flutter is a simple, quick, and accurate indicator of complete isthmus block.

Physician interpretation of electrocardiographic artifact that mimics ventricular tachycardia.

BACKGROUND: Patients who are misdiagnosed with ventricular tachycardia because of electrocardiographic artifact may be subjected to unnecessary procedures. The purpose of this study was to determine how often electrocardiographic artifact is misdiagnosed as ventricular tachycardia. METHODS: Physicians (n = 766) were surveyed with a case simulation that included a two-lead electrocardiographic monitor tracing of artifact simulating a wide-complex tachycardia. RESULTS: The rhythm strip was not recognized as artifact by 52 of the 55 internists (94%), 128 of the 221 cardiologists (58%), and 186 of the 490 electrophysiologists (38%). One hundred fifty-six of the 181 electrophysiologists (88%), 67 of the 126 cardiologists (53%), and 14 of the 15 internists (31%) who misdiagnosed the rhythm as ventricular tachycardia recommended an invasive procedure for further evaluation or therapy. CONCLUSIONS: This physician survey suggests that electrocardiographic artifact that mimics ventricular tachycardia may frequently result in patients being subjected to unnecessary invasive cardiac procedures. Physicians should include artifact in their differential diagnosis of wide complex tachycardias to minimize unneeded procedures.

Prevalence of central venous occlusion in patients with chronic defibrillator leads.

BACKGROUND: Many patients with previously implanted ventricular defibrillators are candidates for an upgrade to a device capable of atrial-ventricular sequential or multisite pacing. The prevalence of venous occlusion after placement of transvenous defibrillator leads is unknown. The purpose of this study was to determine the prevalence of central venous occlusion in asymptomatic patients with chronic transvenous defibrillator leads. METHODS: Thirty consecutive patients with a transvenous defibrillator lead underwent bilateral contrast venography of the cephalic, axillary, subclavian, and brachiocephalic veins as well as the superior vena cava before an elective defibrillator battery replacement. The mean time between transvenous defibrillator lead implantation and venography was 45 +/- 21 months. Sixteen patients had more than 1 lead in the same subclavian vein. No patient had clinical signs of venous occlusion. RESULTS: One (3%) patient had a complete occlusion of the subclavian vein, 1 (3%) patient had a 90% subclavian vein stenosis, 2 (7%) patients had a 75% to 89% subclavian stenosis, 11 (37%) patients had a 50% to 74% subclavian stenosis, and 15 (50%) patients had no subclavian stenosis. CONCLUSIONS: The low prevalence of subclavian vein occlusion or severe stenosis among defibrillator recipients found in this study suggests that the placement of additional transvenous leads in a patient who already has a ventricular defibrillator is feasible in a high percentage of patients (93%).

Complete atrioventricular block after valvular heart surgery and the timing of pacemaker implantation.

The natural history of patients who developed complete atrioventricular block after valvular heart surgery was investigated to determine the optimal timing for pacemaker implantation. Patients who developed complete atrioventricular block within 24 hours after operation, which then persisted for > 48 hours, were unlikely to recover; such patients could potentially undergo earlier pacemaker implantation if otherwise ready for discharge.

Current approaches to evaluation and management of patients with ventricular arrhythmias.

The clinical manifestations of ventricular arrhythmias encompass a broad spectrum, from complete absence of symptoms to sudden death. Although our understanding of the pathophysiology and natural history of these arrhythmias has advanced significantly over the past decade, large gaps in our knowledge remain, especially in patients with heart failure not due to coronary artery disease. We have learned much about the appropriate roles of antiarrhythmic drugs and implantable defibrillators in the prevention of sudden death. Studies performed over the past decade have made clear that the primary treatment for patients at high risk for life-threatening ventricular arrhythmias should be the implantable defibrillator. However, specific syndromes causing ventricular tachyarrhythmias are being recognized, and care must be individualized. Although hospital mortality from acute myocardial infarction has decreased as a result of newer therapies, sudden death after hospital discharge remains an important problem, causing at least 30% of post-infarction deaths, even in patients who have received thrombolytic therapy. Two independent studies have confirmed that patients with asymptomatic non-sustained ventricular tachycardia in the presence of left ventricular ejection fraction < .40 after myocardial infarction who have sustained ventricular tachycardia inducible by electrophysiologic study are at significant risk for sudden death. This risk is significantly reduced by ICD, but not pharmacologic, antiarrhythmic therapy. Our major challenge at this time is not how best to treat high risk patients, but how best to identify them prior to events. Finally, physicians should be aware that many symptomatic ventricular tachycardias are now curable at low risk, using catheters to deliver radiofrequency energy.

Effects of digoxin on acute, atrial fibrillation-induced changes in atrial refractoriness.

BACKGROUND: Atrial fibrillation (AF) shortens the atrial effective refractory period (ERP) and predisposes to further episodes of AF. The acute changes in atrial refractoriness may be related to tachycardia-induced intracellular calcium overload. The purpose of this study was to determine whether digoxin, which increases intracellular calcium, potentiates the acute effects of AF on atrial refractoriness in humans. METHODS AND RESULTS: In 38 healthy adults, atrial ERP was measured at basic drive cycle lengths (BDCLs) of 350 and 500 ms after autonomic blockade. Nineteen patients had been treated with digoxin for 2 weeks. After a several-minute episode of AF, atrial ERP was measured serially at alternating BDCLs. Compared with pre-AF ERPs, the first post-AF ERPs were significantly shorter in both the digoxin and the control groups (P:<0.001). The post-AF ERP at a BDCL of 350 ms shortened to a greater degree in the digoxin group (37+/-16 ms) than in the control group (20+/-13 ms, P:<0.001); similar changes occurred at a BDCL of 500 ms. During post-AF determinations of the atrial ERP, secondary AF episodes occurred significantly more often in the digoxin group (32% versus 16%; P:<0. 04). CONCLUSIONS: After a brief episode of AF, digoxin augments the shortening that occurs in atrial refractoriness and predisposes to the reinduction of AF. These effects occur in the setting of autonomic blockade and therefore are more likely to be due to the effects of digoxin on intracellular calcium than to its vagotonic effects.