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Background: Planar gated blood pool scans are an established method for the evaluation of left ventricular ejection fraction (LVEF) but the camera technology used for these studies has not significantly changed in decades. The purpose of this study was to determine the diagnostic accuracy of new high-efficiency SPECT gated blood pool scans compared to traditional scans and determine if they can be performed with lower radiation doses or faster acquisition times., Methods: Patients undergoing a planar gated blood pool scan on a Na-I SPECT camera who consented to participate were subsequently imaged for 5 minutes in "List Mode" using a high-efficiency SPECT camera. LVEF was calculated for both the planar study and at 1, 2, 3, 4, and 5 minutes of acquisition on the high-efficiency camera. Counts acquired in the field of view, counts in the cardiac blood pool and LVEF were compared., Results: A total of 46 patients were analyzed (48% male, mean age 55 years, and BMI 27.6 kg/m(2)) who received an average Tc-99m dose of 20.3 mCi (5.3 mSv), 17 (37%) with abnormal LVEF's. The Na-I camera averaged 24,514 counts/min/mCi in the field of view and 8662 counts/min/mCi in the cardiac blood pool while the high-efficiency camera averaged 65,219 counts/min/mCi and 41,427 counts/min/mCi, respectively. Compared to the planar calculation of LVEF, 1-minute SPECT LVEF was on average 8.6 ± 10.7 higher, 2 minutes 3.5 ± 7.6 higher, 3 minutes 2.9 ± 8.5 higher, 4 minutes 2.5 ± 7.0 higher, and 5 minutes 1.1 ± 6.2 higher. Good correlation was seen between the SPECT LVEF's and the planar LVEF's across all acquisition times with correlation coefficients of 0.74-0.93., Conclusions: High-efficiency SPECT technology can reduce radiation exposure to patients during gated blood pool imaging or decrease acquisition time while maintaining diagnostic accuracy. Based on the improved count sensitivity with high-efficiency SPECT, a 50% reduction in injected activity may be achievable while maintaining short imaging times of 5 minutes, with further reduction possible at longer imaging times.

Background: Recent literature suggests that the frequency of abnormal SPECT myocardial perfusion imaging (MPI) has decreased over the past two decades despite an increase in the prevalence of many cardiac risk factors. This study examined the trends in the prevalence of obstructive coronary artery disease (CAD) by abnormal and ischemic MPI and invasive angiography., Methods: We analyzed all patients who underwent stress MPI or invasive angiography at two academic centers between January 1996 and December 2012, for their demographic data and study results., Results: A total of 108,654 MPI studies were performed. Over time, the percentage of patients with hypertension, hyperlipidemia, diabetes, and a history of smoking increased. There was a decline in the prevalence of abnormal MPI studies in all patients as well as in those with and without known CAD (from 47.2%, 71.8%, and 31.4% in 1996 to 33.9%, 64.8%, and 18.8% in 2012, respectively, all P < .0001). Similarly, there was a decline in the prevalence of ischemic MPI studies in all patients as well as in those with and without known CAD. A total of 142,924 invasive angiograms were performed. There was a decline in the prevalence of one-vessel and multi-vessel coronary disease (from 29.1% and 53.6% in 1996 to 22.4% and 35.9% in 2012, respectively, all P < .0001)., Conclusions: There has been a temporal decline in the prevalence of abnormal and ischemic MPI studies as well as the frequency and extent of obstructive CAD on angiography. However, this decline was not to the same extent as previously reported, and the overall 34% abnormal MPI rate, with 19% in patients with no known CAD and 65% in patients with known CAD, remains a clinically relevant percentage of patients tested.

Purpose: Previous literature suggests that myocardial perfusion imaging (MPI) adds little to the prognosis of patients who exercise >10 metabolic equivalents (METs) during stress testing. With this in mind, we prospectively tested a provisional injection protocol in emergency department (ED) patients presenting for the evaluation of chest pain in which a patient would not receive an injection of radioisotope if adequate exercise was achieved without symptoms and a negative ECG response., Methods: All patients who presented to the ED over a 5-year period who were referred for stress testing as part of their ED evaluation were included. Patients considered for a provisional protocol were: exercise stress, age <65 years, no known coronary artery disease, and an interpretable rest ECG. Criteria for not injecting included a maximal predicted heart rate ≥85%, ≥10 METs of exercise, no anginal symptoms during stress, and no ECG changes. Groups were compared based on stress test results, all-cause and cardiac mortality, follow-up cardiac testing, subsequent revascularization, and cost., Results: A total of 965 patients were eligible with 192 undergoing exercise-only and 773 having perfusion imaging. After 41.6 ± 19.6 months of follow-up, all-cause mortality was similar in the exercise-only versus the exercise plus imaging group (2.6% vs. 2.1%, p = 0.59). There were no cardiac deaths in the exercise-only group. At 1 year there was no difference in the number of repeat functional stress tests (1.6% vs. 2.1%, p = 0.43), fewer angiograms (0% vs. 4.0%, p = 0.002), and a significantly lower cost ($65 ± $332 vs $506 ± $1,991, p = 0.002; values are in US dollars) in the exercise-only group. The radiation exposure in the exercise plus imaging group was 8.4 ± 2.1 mSv., Conclusions: A provisional injection protocol has a very low mortality, few follow-up diagnostic tests, and lower cost compared to standard imaging protocols. If adopted it would decrease radiation exposure, save time and decrease health-care costs without jeopardizing prognosis.

Background: Recent studies have compared CTA to stress testing and MPI using older Na-I SPECT cameras and traditional rest-stress protocols, but are limited by often using optimized CTA protocols but suboptimal MPI methodology. We compared CTA to stress testing with modern SPECT MPI using high-efficiency CZT cameras and stress-first protocols in an ED population., Methods: In a retrospective, non-randomized study, all patients who underwent CTA or stress testing (ETT or Tc-99m sestamibi SPECT MPI) as part of their ED assessment in 2010-2011 driven by ED attending preference and equipment availability were evaluated for their disposition from the ED (admission vs discharge, length of time to disposition), subsequent visits to the ED and diagnostic testing (within 3 months), and radiation exposure. CTA was performed using a 64-slice scanner (GE Lightspeed VCT) and MPI was performed using a CZT SPECT camera (GE Discovery 530c). Data were obtained from prospectively acquired electronic medical records and effective doses were calculated from published conversion factors. A propensity-matched analysis was also used to compare outcomes in the two groups., Results: A total of 1,458 patients underwent testing in the ED with 192 CTAs and 1,266 stress tests (327 ETTs and 939 MPIs). The CTA patients were a lower-risk cohort based on age, risk factors, and known heart disease. A statistically similar proportion of patients was discharged directly from the ED in the stress testing group (82% vs 73%, P = .27), but their time to disposition was longer (11.0 ± 5 vs 20.5 ± 7 hours, P < .0001). There was no significant difference in cardiac return visits to the ED (5.7% CTA vs 4.3% stress testing, P = .50), but more patients had follow-up studies in the CTA cohort compared to stress testing (14% vs 7%, P = .001). The mean effective dose of 12.6 ± 8.6 mSv for the CTA group was higher (P < .0001) than 5.0 ± 4.1 mSv for the stress testing group (ETT and MPI). A propensity score-matched cohort showed similar results to the entire cohort., Conclusions: Stress testing with ETT, high-efficiency SPECT MPI, and stress-only protocols had a significantly lower patient radiation dose and less follow-up diagnostic testing than CTA with similar cardiac return visits. CTA had a shorter time to disposition, but there was a trend toward more revascularization than with stress testing.

The Q(weak) experiment has measured the parity-violating asymmetry in ep elastic scattering at Q(2)=0.025(GeV/c)(2), employing 145 μA of 89% longitudinally polarized electrons on a 34.4 cm long liquid hydrogen target at Jefferson Lab. The results of the experiment's commissioning run, constituting approximately 4% of the data collected in the experiment, are reported here. From these initial results, the measured asymmetry is A(ep)=-279±35 (stat) ± 31 (syst) ppb, which is the smallest and most precise asymmetry ever measured in ep scattering. The small Q(2) of this experiment has made possible the first determination of the weak charge of the proton Q(W)(p) by incorporating earlier parity-violating electron scattering (PVES) data at higher Q(2) to constrain hadronic corrections. The value of Q(W)(p) obtained in this way is Q(W)(p)(PVES)=0.064±0.012, which is in good agreement with the standard model prediction of Q(W)(p)(SM)=0.0710±0.0007. When this result is further combined with the Cs atomic parity violation (APV) measurement, significant constraints on the weak charges of the up and down quarks can also be extracted. That PVES+APV analysis reveals the neutron's weak charge to be Q(W)(n)(PVES+APV)=-0.975±0.010.

Background: Recently introduced high-efficiency (HE) SPECT cameras with solid-state CZT detectors have been shown to decrease imaging time and reduce radiation exposure to patients. An automated, computer-derived quantification of HE MPI has been shown to correlate well with coronary angiography on one HE SPECT camera system (D-SPECT), but has not been compared to visual interpretation on any of the HE SPECT platforms., Methods: Patients undergoing a clinically indicated Tc-99m sestamibi HE SPECT (GE Discovery 530c with supine and prone imaging) study over a 1-year period followed by a coronary angiogram within 2 months were included. Only patients with a history of CABG surgery were excluded. Both MPI studies and coronary angiograms were reinterpreted by blinded readers. One hundred and twenty two very low (risk of CAD < 5%) or low (risk of CAD < 10%) likelihood subjects with normal myocardial perfusion were used to create normal reference limits. Computer-derived quantification of the total perfusion deficit at stress and rest was obtained with QPS software. The visual and automated MPI quantification were compared to coronary angiography (≥70% luminal stenosis) by receiver operating curve (ROC) analysis., Results: Of the 3,111 patients who underwent HE SPECT over a 1-year period, 160 patients qualified for the correlation study (66% male, 52% with a history of CAD). The ROC area under the curve (AUC) was similar for both the automated and the visual interpretations using both supine only and combined supine and prone images (0.69-0.74). Using thresholds determined from sensitivity and specificity curves, the automated reads showed higher specificity (59%-67% vs 27%-60%) and lower sensitivity (71%-72% vs 79%-93%) than the visual reads. By including prone images sensitivity decreased slightly but specificity increased for both. By excluding patients with known CAD and cardiomyopathies, AUC and specificity increased for both techniques (0.72-0.82). The use of a difference score to evaluate ischemic burden resulted in lower sensitivities but higher specificities for both automated and visual quantification. There was good agreement between the visual interpretation and automated quantification in the entire cohort of 160 unselected consecutive patients (r = 0.70-0.81, P < .0001)., Conclusions: Automated and visual quantification of high-efficiency SPECT MPI with the GE Discovery camera provides similar overall diagnostic accuracy when compared to coronary angiography. There was good correlation between the two methods of assessment. Combined supine and prone stress imaging provided the best diagnostic accuracy.

Background: Previous literature suggests that the results of myocardial perfusion imaging (MPI) add little to the prognosis of patients who exercise >10 metabolic equivalents (METS) during stress testing. With this in mind, we attempted to determine if a provisional injection protocol could be developed in which a patient would not receive an injection of radioisotope if adequate exercise was achieved without symptoms and a negative ECG response. This protocol would save a substantial amount of time, radiation exposure, and cost., Methods: All patients who underwent a stress SPECT MPI over a 6.5-year period from 2004 to 2010 were included. Patients who would have been considered for a standby injection protocol were: exercise stress, age < 65, no known coronary artery disease (CAD), and an interpretable ECG. Patients were retrospectively divided into two groups based on whether they would have received radioisotope or not. Criteria for not injecting included a maximal predicted heart rate ≥ 85%, ≥10 METS of exercise, no symptoms of chest pain or shortness of breath, and no ECG changes (ST depression or arrhythmia). The two groups were then compared based on MPI results and all-cause mortality derived from the Social Security Death Index., Results: A total of 24,689 patients underwent SPECT MPI during this period, and 5,352 would have been eligible for a provisional injection protocol. There were 3,791 (70.8%), who would have been injected and 1,561 (29.2%), who would not have been. Perfusion results were abnormal in 5.9% of non-injected group compared to 14.4% in those who would have been injected. After a mean follow-up of 60.6 ± 21.4 months, 1.1% had died in the non-injected cohort compared to 2.2% in the injected group., Conclusion: A provisional injection protocol defined as age < 65, normal rest ECG, no history of CAD, and high level exercise with a negative ECG response and no symptoms has a very low 5-year all-cause mortality and low yield of MPI. If adopted it would decrease radiation exposure and save time and health care costs without jeopardizing prognosis.

Background: Stress-only Tc-99m MPI saves time, radiation exposure, and a normal study has a benign prognosis. However, a stress-first protocol is relatively labor intensive requiring pre-test screening for suitability and early post-stress image review to determine the need for rest imaging. The purpose of this study was to develop a simple clinical score used prior to a patient's myocardial perfusion imaging (MPI) study to determine if they should undergo a stress-first protocol., Methods: We reviewed all patients who underwent Tc-99m SPECT MPI over a 27-month period and divided them into derivation and validation cohorts. Patients were categorized as having a successful stress-first protocol based on a summed stress score ≤1, with or without attenuation correction. We generated a multivariable model from the derivation cohort to identify demographic and clinical correlates of successful stress-first imaging. Two validation cohorts using a CZT and a conventional SPECT camera were then used to test the performance of the model., Results: The derivation cohort included 1,996 patients and the validation cohort consisted of 1,005 CZT SPECT patients and 2,430 conventional SPECT patients. The following variables were associated with unsuccessful (i.e., abnormal) stress-first imaging: age >65 years (1 point), diabetes (2 points), typical chest pain (2 points), congestive heart failure (3 points), abnormal ECG (4 points), male gender (4 points), and documented CAD (5 points). Emergency Department location (-2 points) was negatively associated with an unsuccessful protocol. An increasing score showed a strong association with an unsuccessful stress-first protocol in both the derivation and the validation cohorts (P < .0001) and dividing the cohorts into low (<5), intermediate (≥5 and <10), and high (≥10) risk scores accurately stratified patients based on their frequencies of unsuccessful stress-first imaging. ROC curve analysis showed excellent prediction in both the derivation and the validation cohorts with an area under the curve of 0.82 and 0.75-0.83, respectively., Conclusions: This pre-test scoring tool accurately identifies patients who can successfully undergo a stress-first imaging protocol without the need for rest imaging and may allow for wider adoption of stress-first imaging protocols.

Background: Stress-only Tc-99m SPECT myocardial perfusion imaging (MPI) decreases test time and patient radiation exposure with a proven benign prognosis of a normal study. The imaging sequence of Tl-201 MPI always starts with the stress portion; therefore, no pre-test decisions are needed regarding the imaging sequence. The recent intermittent Tc-99m shortage afforded the unique opportunity to study an unselected group of patients undergoing Tl-201 imaging., Methods: We retrospectively reviewed all the patients who had SPECT MPI with Tc-99m or Tl-201 over a 1-year period. When Tc-99m was not available, patients received Tl-201. All stress Tl-201 images were routinely processed, and if normal, rest imaging was not done. When Tc-99m was used, patients with lower pre-test probability were selected for a stress-first protocol. We compared the all-cause mortality of patients with normal Tl-201 studies to those with normal stress-only and rest-stress Tc-99m studies using the Social Security Death Index. Unadjusted and risk-adjusted survival analysis was performed. Specific causes of death (cardiac or non-cardiac) were determined by medical record review and contact with treating physicians., Results: A total of 3,658 patients underwent stress MPI during this time period. Of the 1,215 patients who had Tl-201 MPI, 716 (67%) had a normal stress-only study. Out of 2,443 patients who underwent Tc-99m MPI, 70% had normal perfusion with 1,098 normal stress-only studies and 493 normal rest-stress studies. The average follow-up was 23.3 ± 5.3 months. Unadjusted all-cause mortality at the end of follow-up was 7.1% in the Tl-201 stress-only group, 6.3% for Tc-99m stress-only patients, and 4.3% in the Tc-99m rest-stress cohort. After controlling for confounding variables, survival was similar in the three groups (HR 1.07, 95% CI 0.62-1.82, P = .82 for normal Tl-201 stress-only compared to normal Tc-99m rest-stress). The risk-adjusted 1-year survival was between 98.5 and 98.8% in the three groups., Conclusions: Normal stress-only Tl-201 SPECT MPI study has a similarly benign prognosis when compared to Tc-99m rest-stress and Tc-99m stress-only normal SPECT MPI studies. The stress-first design allowed for early triage of over 60% of patients and marked improvement in laboratory efficiency due to shortened test time.

Emergency room evaluations of patients presenting with chest pain continue to rise, and these evaluations which often include cardiac imaging, are an increasing area of resource utilization in the current health system. Myocardial perfusion imaging from the emergency department remains a vital component of the diagnosis or exclusion of coronary artery disease as the etiology of chest pain. Recent advances in camera technology, and changes to the imaging protocols have allowed MPI to become a more efficient way of providing this diagnostic information. Compared with conventional SPECT, new high-efficiency CZT cameras provide a 3-5 fold increase in photon sensitivity, 1.65-fold improvement in energy resolution and a 1.7-2.5-fold increase in spatial resolution. With stress-only imaging, rest images are eliminated if stress images are normal, as they provide no additional prognostic or diagnostic value and cancelling the rest images would shorten the length of the test which is of particular importance to the ED population. The rapid but accurate triage of patients in an ED CPU is essential to their care, and stress-only imaging and new CZT cameras allow for shorter test time, lower radiation doses and lower costs while demonstrating good clinical outcomes. These changes to nuclear stress testing can allow for faster throughput of patients through the emergency department while providing a safe and efficient evaluation of chest pain.

We report a case of iatrogenic claudication as a result of a misplaced percutaneous arterial closure device (PACD) used to obtain hemostasis after cardiac catheterization. The patient presented one week after his procedure with complaints suggestive of right lower extremity claudication. Computed tomographic angiography demonstrated a near total occlusion of the right common femoral artery from a PACD implemented during the cardiac catheterization. The use of PACD's to obtain rapid hemostasis is estimated to occur in half of all cardiac catheterizations. Ischemic complications as a result of these devices must be considered when evaluating post procedural patients with extremity complaints.

Since the first patient underwent the Maze procedure on September 25, 1987, 346 patients have undergone this operation for the treatment of atrial fibrillation. The procedure was designed as an open-heart operation performed through a median sternotomy. It underwent 2 major modifications relatively early in the series, evolving into the so-called Maze-III procedure, which has been used exclusively since April 16, 1992. Since that time, the Maze-III procedure has been adapted to allow it to be done by minimally invasive techniques. In addition, we recently performed the entire procedure in 2 patients without the use of cardiopulmonary bypass. The operative mortality rate has remained at 2% to 3%. This includes patients undergoing concomitant high-risk cardiac surgical procedures and all re-do cases. The overall success rate in curing atrial fibrillation has been 99%. The procedure itself has been shown to cause no permanent damage to the sinus node. The left atrium has been documented to function long-term postoperatively in 93% of patients and the right atrium functions in 99% of patients. The Maze-III procedure remains the surgical procedure of choice for the treatment of medically refractory atrial fibrillation.

In addition to the usual measures that constitute optimal perioperative care after cardiac surgery, the Maze procedure demands several other measures because of certain complications that are unique to this particular operation. These complications include preoperative conditions such as amiodarone therapy, thromboembolism, diastolic dysfunction of the left ventricle, and associated valvular heart disease, as well as intraoperative differences that include multiple atriotomies and excision of both atrial appendages. The most common postoperative complications are atrial arrhythmias, excessive fluid retention, and pulmonary complications. In this article, we outline our own approach to the perioperative care of patients undergoing the Maze procedure.

Previous studies have suggested that the Maze procedure is not as effective in controlling atrial fibrillation when the arrhythmia is associated with significant valvular heart disease. In this study, we evaluate our own results in 83 patients who underwent 96 valve procedures in combination with the Maze-III procedure. Our results indicate that the Maze-III procedure is just as safe and effective in controlling atrial fibrillation associated with valvular heart disease as it is in controlling atrial fibrillation not associated with valvular heart disease.

In this study, we have demonstrated that topoisomerase I DNA relaxing activity is protected against a severe heat shock in T cells made thermotolerant by a prior modest heat treatment. However, following a severe heat-shock challenge and incubation at 37 degrees C, topoisomerase activity in the control population eventually returned to levels similar to those detected in thermotolerant cells. This recovery of topoisomerase activity appears to result from the renaturation of heat-inactivated enzyme rather than from synthesis of new protein because the rate of recovery of catalytic activity was not inhibited by the presence of the protein synthesis inhibitor, cycloheximide.