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Papers by Thomas Crawford

Circulation, 2007

Background— Radiofrequency catheter ablation of atrial fibrillation (AF) guided by complex fracti... more Background— Radiofrequency catheter ablation of atrial fibrillation (AF) guided by complex fractionated atrial electrograms has been reported to eliminate AF in a large proportion of patients. However, only a small number of patients with chronic AF have been included in previous studies. Methods and Results— In 100 patients (mean age, 57±11 years) with chronic AF, radiofrequency ablation was performed to target complex fractionated atrial electrograms at the pulmonary vein ostial and antral areas, various regions of the left atrium, and the coronary sinus until AF terminated or all identified complex fractionated atrial electrograms were eliminated. Ablation sites consisted of ≥1 pulmonary vein in 46% of patients; the left atrial septum, roof, or anterior wall in all; and the coronary sinus in 55%. During 14±7 months of follow-up after a single ablation procedure, 33% of patients were in sinus rhythm without antiarrhythmic drugs, 38% had AF, 17% had both AF and atrial flutter, 9% h...

Circulation. Arrhythmia and electrophysiology, 2013

Ventricular arrhythmias have been described to originate from intramural locations. Intramural sc... more Ventricular arrhythmias have been described to originate from intramural locations. Intramural scar can be assessed by delayed-enhanced MRI, but MRIs cannot be performed on every patient. The objective of this study was to assess the value of voltage mapping to detect MRI-defined intramural scar and to correlate the scar with ventricular arrhythmias. In 15 consecutive patients (3 women; age 55±16 years; ejection fraction, 49±13%) with structural heart disease, intramural scar was detected by delayed-enhanced MRI. All patients underwent endocardial unipolar and bipolar voltage mapping guided by the registered intramural scar. Scar volume by MRI was 11.7±8 cm3 with a scar thickness of 4.6±0.7 mm and a preserved endocardial/epicardial rim of 3.3±1.6 and 4.8±2.6 mm, respectively. Endocardial bipolar voltage was 1.6±1.73 mV at the scar, 2.12±2.15 mV in a 1 cm perimeter around the scar, and 2.83±3.39 mV in remote myocardium without scar. The corresponding unipolar voltage was 4.94±3.25, 6...

American Journal of Tropical Medicine and Hygiene, 2014

Approximately 8 million people have Trypanosoma cruzi infection, and nearly 30% will manifest Cha... more Approximately 8 million people have Trypanosoma cruzi infection, and nearly 30% will manifest Chagas cardiomyopathy (CC). Identification of reliable early indicators of CC risk would enable prioritization of treatment to those with the highest probability of future disease. Serum markers and electrocardiogram (EKG) changes were measured in 68 T. cruzi-infected individuals in various stages of cardiac disease and 17 individuals without T. cruzi infection or cardiac disease. T. cruzi-infected individuals were assigned to stage A (normal EKG/chest x-ray [CXR]), B (abnormal EKG/ normal CXR), or C (abnormal EKG/cardiac structural changes). Ten serum markers were measured using enzyme-linked immunosorbent assay (ELISA)/Luminex, and QRS scores were calculated. Higher concentrations of transforming growth factor-β1 (TGFβ1), and TGFβ2 were associated with stage B compared with stage A. Matrix Metalloproteinase 2 (MMP2), Tissue Inhibitors of MMP 1, QRS score, and Brain Natriuretic Protein rose progressively with increasing CC severity. Elevated levels of several markers of cardiac damage and inflammation are seen in early CC and warrant additional evaluation in longitudinal studies.

C ardiac sarcoidosis can present with ventricular arrhythmias and sudden death, even in asymptoma... more C ardiac sarcoidosis can present with ventricular arrhythmias and sudden death, even in asymptomatic patients with normal cardiac function. 1-3 In addition, the progression of cardiac sarcoidosis (CS) can be unpredictable, and there are no validated sudden death risk stratification methods for these patients. For these reasons, implantable cardioverter defibrillator (ICD) implantation has been advocated for all patients with CS, regardless of the extent of myocardial involvement. 4 Clinical Perspective on p 1115 The purpose of this study was to assess whether delayed enhancement (DE) on cardiac MRI is associated with ventricular tachycardia in patients with CS and preserved or mildly reduced left ventricular function. Methods Multicenter Registry for Cardiac Sarcoidosis A multicenter registry for the purpose of research collaboration of this rare disease was established, with the University of Michigan serving as the coordinating center for this study. This registry was

Sarcoidosis is a disease in which parts of the body develop granulomas, clumps of immune system c... more Sarcoidosis is a disease in which parts of the body develop granulomas, clumps of immune system cells responding to a perceived threat (Figure). These most commonly form in the lungs, in lymph nodes, and on the skin, but can appear in virtually any organ. Granulomas can interfere with normal organ function, causing symptoms that may be similar to those of other diseases. Cardiac sarcoidosis refers to the development of sarcoid granulomas in the heart muscle. This can affect the heart’s ability to pump blood to the rest of the body, with potentially life-threatening consequences.

Nature Reviews Cardiology

Pacemaker therapy is inaccessible to most patients with bradycardia in Africa. Use of recondition... more Pacemaker therapy is inaccessible to most patients with bradycardia in Africa. Use of reconditioned pacemakers has been proposed as a safe, efficacious, and ethical means of delivering this therapy.

Journal of interventional cardiac electrophysiology : an international journal of arrhythmias and pacing, Jan 11, 2018

The endpoint for radiofrequency catheter ablation (RFA) of cavo-tricuspid isthmus (CTI)-dependent... more The endpoint for radiofrequency catheter ablation (RFA) of cavo-tricuspid isthmus (CTI)-dependent atrial flutter (AFL) is complete conduction block along the CTI. The purpose of this study is to evaluate the utility of the temporal relationship between the P wave and the local atrial electrograms in determining complete CTI block. RFA of CTI was performed in 125 patients (age 63 ± 11 years). During pacing from the coronary sinus (CS), the intervals from the peak of the P wave (P) in lead V to the second component of the local atrial electrogram (A) along the ablation line (P-A) and from the end of the P wave (P) to A (P-A) were investigated before and after complete block in the first 100 patients (training set). In the next 25 patients (validation set), P-A and P-A intervals were prospectively assessed to determine CTI block. The mean P-A and P-A immediately before complete block were - 15±24 and - 39±23 ms compared to 49 ± 17 and 21 ± 16 ms after CTI block (P < 0.0001). P-A ≥ 2...

Journal of cardiovascular electrophysiology, Jan 26, 2017

Although noninferiority of cryoballoon ablation (CBA) and radiofrequency catheter ablation for an... more Although noninferiority of cryoballoon ablation (CBA) and radiofrequency catheter ablation for antral pulmonary vein isolation (APVI) has been reported in patients with paroxysmal atrial fibrillation (PAF), it is not clear whether contact force sensing (CF-RFA) and CBA with the 2(nd) generation catheter have similar procedural costs and long-term outcomes. The objective of this study is to compare the long-term efficacy and cost implications of CBA and CF-RFA in patients with PAF. A 1(st) APVI was performed in 146 consecutive patients (age: 63 ± 10 years, men: 95 [65%], left atrial diameter: 42 ± 6 mm) with PAF using CBA (71) or CF-RFA (75). Clinical outcomes and procedural costs were compared. The mean procedure time was significantly shorter with CBA than with CF-RFA (98 ± 39 vs 158 ± 47 min, P < 0.0001). Despite a higher equipment cost in the CBA than the CF-RFA group, the total procedure cost was similar between the 2 groups (P = 0.26), primarily driven by a shorter procedure...

JACC: Clinical Electrophysiology

OBJECTIVES This study sought to develop a validated, reproducible sterilization protocol, which c... more OBJECTIVES This study sought to develop a validated, reproducible sterilization protocol, which could be used in the reprocessing of cardiac implantable electronic devices (CIEDs). BACKGROUND Access to cardiac CIED therapy in high-income and in low-and middle-income countries varies greatly. CIED reuse may reduce this disparity. METHODS A cleaning and sterilization protocol was developed that includes washing CIEDs in an enzymatic detergent, screw cap and set screw replacement, brushing, inspection, and sterilization in ethylene oxide. Validation testing was performed to assure compliance with accepted standards. RESULTS With cleaning, the total mean bioburden for each of 3 batches of 10 randomly chosen devices was reduced from 754 to 10.1 colony-forming units. After sterilization with ethylene oxide, with 3 half-cycle and 3 full-cycle processes, none of the 90 biological indicator testers exhibited growth after 7 days. Through cleaning and sterilization, protein and hemoglobin concentrations were reduced from 99.2 to 1.42 mg/cm 2 and from 21.4 to 1.03 mg/cm 2 , respectively. Mean total organic carbon residual was 1.44 parts per million (range 0.36 to 2.9 parts per million). Endotoxin concentration was not detectable at the threshold of <0.03 endotoxin units/ml or <3.0 endotoxin units/device. Cytotoxicity and intracutaneous reactivity tests met the standards set by the Association for Advancement of Medical Instrumentation and the International Organization for Standardization. CONCLUSIONS CIEDs can be cleaned and sterilized according to a standardized protocol achieving a 12-log reduction of inoculated product, resulting in sterility assurance level of 10-6 .

Heart rhythm, Jan 29, 2017

The role of the ligament of Marshall (LOM) in patients with atrial fibrillation (AF) has not been... more The role of the ligament of Marshall (LOM) in patients with atrial fibrillation (AF) has not been well defined. The purpose of this study was to describe the role of the LOM in patients with AF and related arrhythmias. Fifty-six patients (mean age 63 ± 11 years; persistent AF in 48 [86%]; ejection fraction 0.49 ± 0.13; left atrial diameter 4.7 ± 0.6 cm) with LOM-mediated arrhythmias were included. A LOM-pulmonary vein (PV) connection was present in 18 patients (32%) and was eliminated with radiofrequency (RF) ablation at the left lateral ridge or crux (n = 12), at the mitral annulus (n = 3), or with alcohol/ethanol (EtOH) ablation of the vein of Marshall (VOM; n = 3). A LOM-mediated atrial tachycardia (AT) was present in 13 patients (23%). Thirty-one patients with refractory mitral isthmus conduction were referred for potential EtOH ablation. In the 6 patients in whom VOM was injected during perimitral reentry, EtOH resulted in slowing in 3 patients and termination in 1 patient. In ...

Heart rhythm, Nov 5, 2017

Frequent premature ventricular complexes (PVC) have been associated with increased mortality. How... more Frequent premature ventricular complexes (PVC) have been associated with increased mortality. However, the optimal approach to the risk stratification in these patients is unclear. The purpose of this study was to prospectively assess the use of cardiac magnetic resonance imaging (MRI) and programmed ventricular stimulation to identify patients with PVCs undergoing radiofrequency ablation at risk for adverse long-term outcomes. A total of 321 consecutive patients (52±15 years; males: 157 [49%], left ventricular ejection fraction: 51±12%) underwent PVC ablation between 2004 and 2015 preceded by a cardiac MRI to assess for structural heart disease (SHD). Programmed stimulation was performed at the time of the ablation procedure. If ventricular tachycardia (VT) was induced in the presence of SHD, a cardioverter-defibrillator (ICD) was implanted. SHD was identified by MRI in 64 patients (20%) and sustained monomorphic VT was inducible in 15 patients (5%). Fourteen patients had both SHD ...

Pacing and clinical electrophysiology : PACE, Jan 17, 2017

Medical devices increasingly depend on software. While this expands the ability of devices to per... more Medical devices increasingly depend on software. While this expands the ability of devices to perform key therapeutic and diagnostic functions, reliance on software inevitably causes exposure to hazards of security vulnerabilities. This article uses a recent high-profile case example to outline a proactive approach to security awareness that incorporates a scientific, risk-based analysis of security concerns that supports ongoing discussions with patients about their medical devices. This article is protected by copyright. All rights reserved.

Journal of Cardiovascular Electrophysiology, Jul 19, 2012

Circulation, Oct 31, 2006

JACC: Basic to Translational Science, 2016

Intracardiac serum galectin (Gal)-3 levels are shown to be greater in patients with persistent th... more Intracardiac serum galectin (Gal)-3 levels are shown to be greater in patients with persistent than paroxysmal atrial fibrillation (AF), and the Gal-3 level was an independent predictor of AF recurrences after a single ablation procedure. In a sheep model, the Gal-3 inhibitor GM-CT-01 (GMCT) reduced atrial fibroblast proliferation in vitro. GMCT mitigated atrial dilation, myocyte hypertrophy, fibrosis, and the expected increase in DF during transition to persistent AF. GMCT-treated sheep hearts had longer action potential durations, and fewer rotors and wavebreaks during AF than control. GMCT increased the number of spontaneous AF terminations and reduced overall AF burden.

Circulation, Nov 22, 2011

Introduction Patients with cardiac sarcoidosis (CS) are at increased risk for sudden death from v... more Introduction Patients with cardiac sarcoidosis (CS) are at increased risk for sudden death from ventricular arrhythmias. There is little evidence regarding the efficacy and safety of implantable ca...

Circulation, Nov 23, 2010

Transactions of the American Clinical and Climatological Association, 2015

It is estimated that nearly 1 million patients in low-income countries die every year from bradya... more It is estimated that nearly 1 million patients in low-income countries die every year from bradyarrhythmias coupled with no access to a pacemaker. At the same time, it is estimated that tens of thousands of used devices could be harvested from hospitals, funeral homes, and crematories in wealthy nations if such a practice was legal and proven to be safe and efficacious. Project My Heart Your Heart is a collaborative, multinational effort with a goal of making pacemaker recycling a reality. Since its inception 4 years ago, the project has studied beliefs and attitudes of this idea among patients, pacemaker recipients, funeral home directors, and arrhythmia specialists. The project has explored the safety and efficacy of this practice in several small pilot studies. Nearly 15,000 used devices have been received and evaluated. Efforts to fully define optimal methods for sterilization and device processing have progressed positively. Safe, effective pacemaker recycling is possible and i...