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Background: Myotonic dystrophy type 1 (DM1) is a neurological disorder with known cardiac involvement, including conduction disturbances, arrhythmias, and ventricular dysfunction. We studied which clinical and electrocardiographic features are associated with structural cardiac abnormalities., Methods: History, physical examination, electrocardiography, and genetic testing were performed on 382 patients with DM1, and cardiac imaging was performed on 100 of these patients., Results: Clinical congestive heart failure was found in 7 of the 382 patients (1.8%). Structural cardiac abnormalities determined with cardiac imaging included left ventricular hypertrophy (19.8%), left ventricular dilatation (18.6%), left ventricular systolic dysfunction (14.0%), mitral valve prolapse (13.7%), regional wall motion abnormality (11.2%), and left atrial dilatation (6.3%). Left ventricular systolic dysfunction was associated with increasing age (relative risk [RR], 1.9 per decade; 95% CI, 1.1-3.2; P =.02), cytosine-thymine-guanine (CTG) repeat length (RR, 2.8 per 500 repeats; 95% CI, 1.3-6.3; P =.01), P-R >200 ms (RR, 14.7; 95% CI, 3.0-73.1; P =.001), and QRS >120 ms (RR, 5.7; 95% CI, 1.5-21.8; P =.01). P-R >200 ms was predictive of regional wall motion abnormalities. QRS >120 ms correlated with regional wall motion abnormalities and left atrial dilatation., Conclusions: Several clinical and electrocardiographic findings in patients with DM1 are significantly associated with structural heart abnormalities. These results suggest an underlying genetic and pathophysiologic correlate that may lead to cardiac disease in these patients.

Objectives: The purpose of this study was to determine whether gender differences exist in the characteristics and outcomes for out-of-hospital cardiac arrest (OHCA) occurring in a rural setting.Background: In urban settings, women have a lower incidence of OHCA than men but otherwise a comparable survival for ventricular fibrillation (VF) OHCA. Whether OHCA gender differences exist in rural settings is not clear.Methods: The study consisted of a prospective collection and analysis of nontraumatic, adult OHCA prompting a 911 call in six rural Indiana counties.Results: Over an average period of 2.2 years, 138 women and 250 men experienced OHCA (annual incidence rate: 56.4 per 100,000 men and 29.3 per 100,000 women). Women were older, less likely to experience OHCA in a public setting, more likely to be in an extended care facility, and less likely to have a witnessed arrest than were men. Women were less likely to present with an initial rhythm of VF than men (33.3% vs 53.6%, P < .001). Women in VF had a longer time interval from 911 call to first shock compared with men. Women had poorer survival to hospital discharge for all OHCA (2.2% vs 7.2%, P = .04) and VF OHCA (2.2% vs 13.4%, P = .05) compared with men. After age adjustment, female gender remained associated with a poorer OHCA survival outcome. With adjustment for all significant arrest characteristics, female gender was no longer associated with survival.Conclusions: In a rural population, women suffering OHCA have a dismal survival rate likely because of multiple unfavorable arrest characteristics. [ABSTRACT FROM AUTHOR]

Objectives: We used optical mapping to characterize the reentrant circuit of ventricular tachycardia (VT) during acute myocardial infarction (MI) in isolated canine left ventricular preparations.Background: The nature of the reentrant circuit that underlies VT during acute MI is not well understood.Methods: Using optical mapping in isolated canine left ventricular preparations, we characterized the reentrant circuit of monomorphic VT (mean cycle length 245.3 +/- 15.6 ms, n = 7) induced by programmed stimulation during acute MI.Results: Optical mapping during VT revealed a functional reentrant circuit consisting of four components: (1) a protected isthmus located between the infarction area and the functional line of block; (2) an entrance site located at one end of the isthmus; (3) an exit site located at the other end of the isthmus; and (4) an outer loop consisting of nonischemic normal tissue, connecting the exit and entrance sites. Rate-dependent slow conduction within the border zone was associated with significant changes (n = 6) in action potential amplitude (99.1 +/- 0.4 vs 71.4 +/- 0.6 mV, P < .01), maximal diastolic potential (-80.6 +/- 0.2 vs -65.4 +/- 0.6 mV, P < .05), action potential duration at 90% repolarization (APD(90); 188.4 +/- 1.0 vs 164.3 +/- 3.1 ms, P < .05), and dV/dt (302.4 +/- 7.9 vs 168.5 +/- 3.6 V/s, P < .05). Compared to preparations with no inducible VT (n = 7), formation of a functional line of block was the key mechanism for initiation of functional reentry in preparations with VT. When comparing preparations with sustained and nonsustained VT, preservation of slow conduction over the isthmus was the key component for maintenance of sustained VT.Conclusions: The reentrant circuit of monomorphic VT in the setting of acute MI involved both the infarction border zone and nonischemic normal tissue. The underlying mechanism is related to the presence of rate-dependent slow conduction and the development of a functional line of block in the border zone. [ABSTRACT FROM AUTHOR]

Introduction: Cardiac myopathy manifesting with conduction disturbances and arrhythmias is common in the neurologic disease myotonic dystrophy. We studied whether the severity of cardiac involvement in myotonic dystrophy correlates with the severity of the genetic abnormality cytosine-thymine-guanine (CTG) repeat expansion. Methods and Results: History, physical examination, ECG evaluation, and genetic testing were performed in patients with a clinical diagnosis of myotonic dystrophy. In 342 of 385 patients, the diagnosis was confirmed by CTG repeat expansion. In these patients, the muscular disability severity correlated with age and CTG repeat length (r = 0.44, P < 0.001). An arrhythmia diagnosis was present in 19 (5.6%) patients with a likelihood of diagnosis correlating with age (relative risk [RR] 2.2 per decade, 95% confidence intervals [CI] 1.4 to 3.4, P = 0.001) and CTG repeat length (RR 2.9 per 500 repeats, 95% CI 1.5 to 5.4, P = 0.001). ECGs were abnormal in 222 (64.9%) of the patients. Age, CTG repeat length, and male gender were factors found to correlate with ECG conduction abnormalities quantitated by the PR interval (r = 0.43, P < 0.001) and QRS duration (r = 0.32, P < 0.001). A 24-hour ambulatory ECG was abnormal in 95 (29.6%) of 321 recordings. The presence of an abnormality correlated with age (RR 1.5 per decade, 95% CI 1.2 to 1.9, P < 0.001) and CTG repeat length (RR 1.6 per 500 repeats, 95% confidence intervals 1.1 to 2.2, P = 0.01). Conclusion: The severity of skeletal and cardiac myopathy in myotonic dystrophy correlates with age and CTG repeat length, suggesting a similar mechanism causing a time-dependent degenerative process. [ABSTRACT FROM AUTHOR]

Summary: The adverse event (AE) profile of lay volunteer CPR and public access defibrillation (PAD) programs is unknown. We undertook to investigate the frequency, severity, and type of AE''s occurring in widespread PAD implementation. Design: A randomized-controlled clinical trial. Setting: One thousand two hundred and sixty public and residential facilities in the US and Canada. Participants: On-site, volunteer, lay personnel trained in CPR only compared to CPR plus automated external defibrillators (AEDs). Intervention: Persons experiencing possible cardiac arrest receiving lay volunteer first response with CPR+AED compared with CPR alone. Main outcome measure: An AE is defined as an event of significance that caused, or had the potential to cause, harm to a patient or volunteer, or a criminal act. AE data were collected prospectively. Results: Twenty thousand three hundred and ninety six lay volunteers were trained in either CPR or CPR+AED. One thousand seven hundred and sixteen AEDs were placed in units randomized to the AED arm. There were 26,389 exposure months. Only 36 AE''s were reported. There were two patient-related AEs: both patients experienced rib fractures. There were seven volunteer-related AE''s: one had a muscle pull, four experienced significant emotional distress and two reported pressure by their employee to participate. There were 27 AED-related AEs: 17 episodes of theft involving 20 devices, three involved AEDs that were placed in locations inaccessible to the volunteer, four AEDs had mechanical problems not affecting patient safety, and three devices were improperly maintained by the facility. There were no inappropriate shocks and no failures to shock when indicated (95% upper bound for probability of inappropriate shock or failure to shock=0.0012). Conclusions: AED use following widespread training of lay-persons in CPR and AED is generally safe for the volunteer and the patient. Lay volunteers may report significant, usually transient, emotional stress following response to a potential cardiac arrest. Within the context of this prospective, randomized multi-center study, AEDs have an exceptionally high safety profile when used by trained lay responders. [Copyright &y& Elsevier]

Abstract: [11C]Hemicholinium-15 ([11C]HC-15) and [18F]hemicholinium-15 ([18F]HC-15) have been synthesized as new potential PET tracers for the heart high-affinity choline uptake (HACU) system. [11C]HC-15 was prepared by N-[11C]methylation of the appropriate precursor, 4-methyl-2-phenyl-morpholin-2-ol, using [11C]CH3OTf in 55–70% radiochemical yield decay corrected to end of bombardment (EOB) and 2–3Ci/μmol specific activity at end of synthesis (EOS). [18F]HC-15 was prepared by N-[18F]fluoromethylation of the precursor using [18F]FCH2OTf in 20–30% radiochemical yield decay corrected to EOB and >1.0Ci/μmol specific activity at EOS. The biodistribution of both compounds was determined in rats at 20min post-intravenous injection, and the results show the heart region uptakes 1.32±0.75%ID/g in R-ventricle for [11C]HC-15 and 1.28±0.81%ID/g in L-ventricle for [18F]HC-15, respectively. The dynamic PET imaging studies of [11C]HC-15 in rats were acquired 60min post-intravenous injection of the tracer using the IndyPET-II scanner. For the blocking experiments, the rats were intravenously pretreated with 3.0mg/kg of unlabeled HC-15 prior to [11C]HC-15 injection. [11C]HC-15 rat heart PET studies show rapid heart uptake to give clear heart images. The rat heart PET blocking studies found no significant blocking effect. The dynamic PET studies in normal and ablated dogs were performed using Siemens PET scanner with [13N]NH3, [11C]HC-15, and [18F]HC-15. PET studies in dogs of both [11C]HC-15 and [18F]HC-15 also show significant heart uptake and give images of the heart. However, there is no significant change in [11C]HC-15 L-ventricle uptake following radiofrequency ablation in the dog. These results suggest that the localization of HC-15 tracers in the heart is mediated by non-specific processes, and the visualization of HC-15 tracers on the heart is related to non-specific binding of HACU. [Copyright &y& Elsevier]

Despite substantial progress in the diagnosis and treatment of acute ST-segment elevation myocardial infarction (STEMI), implementation of this knowledge into routine clinical practice has been variable. It has become increasing clear that primary percutaneous coronary intervention (PCI) is the preferred method of reperfusion if it can be performed in a timely manner. Recent European data suggest that transfer for direct PCI may also be preferable to fibrinolytic therapy. We believe it is time to establish a national policy for treatment of patients with STEMI to develop a coordinated system of care similar to that of the level 1 trauma system. [Copyright &y& Elsevier]