Vincent J.B. Robinson

Characteristics of patients with cervical spinal injury requiring permanent pacemaker implantation.

Acute cervical spinal cord injury frequently results in bradydysrhythmia, which may lead to hypotension and asystole. Such symptoms are more common in the first 2 weeks after the injury. Treatment modalities include atropine, epinephrine, aminophylline, and pacemaker insertion. The criteria for pacemaker use in this population are not well defined. We describe characteristics of 3 patients who required permanent, transvenous pacemaker implantation for recurrent symptoms. In 2 of the 3 patients, transcutaneous pacing failed to provide adequate protection. Transcutaneous pacemakers are not reliable, as was the case of these patients, and early consideration for transvenous pacemaker insertion may be indicated, especially in hemodynamically unstable patients. In this report, all 3 patients required permanent pacemaker implantation.

Pharmacologic stress myocardial perfusion imaging.

Abstract: Pharmacologic stress agents (dipyridamole, adenosine and dobutamine) allow virtually all patients to be safely assessed for ischemic heart disease. These agents have mild but significant side effects, mandating a thorough knowledge of indications, contraindications, side effects and management before their use. Adjunctive exercise improves image quality in vasodilator pharmacologic myocardial perfusion imaging. Diabetics, especially women, have a much higher cardiac event rate than nondiabetics for an equal amount of ischemia. They also have a higher incidence of asymptomatic ischemia. There is growing support for screening with myocardial perfusion imaging (MPI) for asymptomatic ischemia in diabetics. The ability of MPI to identify hypocontractile but viable myocardium, thus predicting improvement in myocardial function after revascularization, is one of the most powerful uses of the modality. Vasodilator MPI should be used as the initial test in patients with left bundle branch block or paced ventricular rhythm, even if they are able to exercise.

Diastolic Filling Parameters Derived from Myocardial Perfusion Imaging Can Predict Left Ventricular End-Diastolic Pressure at Subsequent Cardiac Catheterization

Morbidity and mortality increase when diastolic dysfunction accompanies coronary artery disease (CAD). An elevated stress 201Tl lung-to-heart ratio (LHR) is a traditional marker of elevated left ventricular end-diastolic pressure (LVEDP), which adds prognostic value in CAD. Since the introduction of 99mTc-labeled agents, this valuable marker has been lost. Hence, there is only a limited ability to assess diastolic dysfunction by myocardial perfusion imaging (MPI). Methods: Fifty-two consecutive patients with an ejection fraction of ≥45% underwent MPI and cardiac catheterization within 15 d. Peak filling rate (PFR), time to PFR (TPFR), and filling rate during the first third of diastole (1/3FR) were obtained from MPI with SPECT software. Resting 201Tl LHR was calculated manually, and LVEDP was obtained at catheterization. Results: PFR, TPFR, and 1/3FR correlated significantly with LVEDP (r = −0.53, 0.45, and −0.45, respectively; P = 0.00005, 0.0009, and 0.0009, respectively), whereas resting 201Tl LHR did not (r = 0.10, P = 0.49). Receiver-operating-characteristic curve analysis of PFR, TPFR, and 1/3FR for detecting LVEDPs of ≥18 mm Hg showed areas under the curve of 0.83, 0.75, and 0.80, respectively. The combination of PFR and 1/3FR showed a negative predictive value of 84%, a positive predictive value of 86%, and a specificity of 94%. Conclusion: Diastolic filling variables obtained with the SPECT software showed a significant correlation with LVEDP. PFR, TPFR, and 1/3FR were superior to resting 201Tl LHR and showed good sensitivity, specificity, and predictive power for detecting LVEDPs of ≥18 mm Hg. Hence, combining data on the presence of perfusion defects with data on diastolic impairments can be achieved by adding these variables to MPI results.

Angina, an Unusual and Late Complication of the Cabrol Procedure: A Case Report and Review of the Literature

Several techniques exist for surgical reimplantation of the coronary arteries to a composite aortic graft for repair of the ascending aorta. The Cabrol graft is an attachment of a Dacron tube between the coronary arteries and the composite aortic graft in aortic root replacement. Very late presentation of myocardial ischemia related to the Cabrol conduit graft is exceedingly rare. We report a rare and late development of angina due to a dysfunctional Cabrol conduit, which was successfully cured with coronary bypass grafting. Knowledge of this technique is vital for the accurate interpretation of coronary angiograms and CT scan findings and crucial for the treatment planning in patients who have had previous implantation of the Cabrol graft.

The D-dimer assay: A possible tool in the evaluation of atrial thrombosis

Atrial fibrillation (AF) is a common arrhythmia seen in clinical practice, and affects more than 4% of the population older than 60 years of age. Peripheral thromboembolism contributes significantly to the observed morbidity and mortality. Symptomatic AF, before cardioversion to normal sinus rhythm, requires either exclusion of atrial thrombi using transesophageal echocardiography (TEE) or the conventional use of three weeks of adequate anticoagulation. The exclusion of atrial thrombi by TEE, a nontomographic technique but comparable with conventional treatment of AF in outcomes, has inherent limitations due to the complex three-dimensional multilobed anatomy of the left atrial appendage, where the majority of atrial thrombi arise. Also, the conventional treatment of three weeks of therapeutic anticoagulation before cardioversion reportedly does not always eliminate atrial thrombi. Plasma D-dimer constitutes an antigen-antibody reaction to the dimeric final degradation product of a mature clot. An elevated fibrin D-dimer has a high sensitivity for intravascular thrombosis and, hence, may improve the evaluation of a patient with AF before cardioversion in addition to a TEE. A case is presented in which a positive D-dimer resulted in performing TEE to document atrial thrombosis and the complications of previous bacterial endocarditis. In the present case, this involved aortic root abscess formation and acute aortic regurgitation because of flailing of the noncoronary cusp that resulted in recurrent pulmonary edema.

Endotoxemia alters splanchnic capacitance

The splanchnic circulation constitutes a major portion of the total capacitance vasculature and may affect venous return and subsequently cardiac output during low output states. This study assessed the effects of rapid (10 microg/kg over 5 min) and slow (10 microg/kg over 60 min) induction of endotoxin (Escherichia coli) shock on splanchnic blood volume in 8 farm swine. Blood volume was measured by using Tc99m-labeled erythrocytes and radionuclide imaging. Baseline arterial pressure (MAP), central venous pressure (CVP), and liver, splenic, mesenteric and total splanchnic volumes were stable during the 30-min baseline. Approximately 30 min after the rapid endotoxin infusion, splenic volume decreased by 45%, whereas liver volume increased by 40% and MAP decreased by 60% (P < 0.01). The reduction in splenic volume occurred within 10 min of the endotoxin infusion, whereas liver volume changes occurred after MAP reduction. The slow endotoxin infusion also reduced splenic volume by approximately 50% (P = 0.05), whereas MAP declined by 30% (P < 0.05). However, the slow endotoxin infusion lowered liver volume (P < 0.05). Mesenteric volume was unaffected by the fast or slow endotoxin infusion. Total splanchnic volume was unaffected by the fast infusion but decreased by 37% in the slow infusion group (P < 0.05). In summary, E. coli endotoxin reduces splenic blood volume and increases liver blood volume after acute hypotension ensues. Endotoxin does not increase total splanchnic blood volume and may actually decrease total splanchnic volume in the absence of circulatory collapse. This endotoxin shock model is not associated with blood volume pooling in the splanchnic capacitance circulation.

Osteogenic sarcoma associated with the Rothmund-Thomson syndrome

The Rothmund-Thomson syndrome (RTS), also called poikiloderma congenitale, is a rare autosomal recessive disorder characterized by photosensitivity, poikiloderma of the face and extremities, juvenile cataracts, skeletal abnormalities, and a higher incidence of malignancy. Presented is the case of a 6-year-old boy with RTS who developed an osteogenic sarcoma of the tibia. A bone scan showed bilateral radius agenesis and a hot bone lesion in the proximal tibia metaphysis. An incisional bone biopsy led to a diagnosis of osteogenic sarcoma. There is an association between RTS and osteosarcoma, and there should be a high index of suspicion when patients with RTS develop bony pain.

Race/ethnicity determines the relationships between oxidative stress markers and blood pressure in individuals with high cardiovascular disease risk

Oxidative stress (OS) and cardiovascular (CV) reactivity are related to CV morbidity and mortality. However, little is known about the relationships between these CV risk factors and their confounders. We hypothesize that higher OS is linked to higher blood pressure (BP) reactivity to acute laboratory stressors and in the natural setting. We studied 137 subjects with a family history of hypertension and early myocardial infarction. There were 63 European Americans (EAs) (38 males) and 74 African Americans (AAs) (35 males), aged 19–36 (27.6±3.1). The protocol included a competitive video game, cold stressor and ambulatory BP recording. Blood samples were drawn six times for OS markers (8-hydroxydeoxyguanosine (8-OHdG) and 8-Isoprostane) assay. Repeated measures analyses of covariance were used to test for mean differences and Pearson correlations were used to test OS and BP associations. There were no significant race/ethnicity differences in BP reactivity to either stressor (both P’s>0.48). 8-OHdG levels were significantly lower across all time points for AAs than for EAs (P<0.05), while levels of 8-isoprostane did not differ significantly (P>0.10). Averaged 8-OHdG levels significantly correlated with systolic blood pressure (SBP) reactivity (r=0.45, <0.01) and 24-h, daytime and nighttime SBP (r range=0.37–0.42, all P’s<0.02) for EAs but not for AAs, whereas 8-isoprostane levels were significantly correlated with reactive SBP and nighttime diastolic blood pressure (DBP) (both r’s=0.38, P<0.01) for AAs but not for EAs. These findings suggest a link between OS and BP changes in subjects at high risk for CV disease (CVD). Further, race/ethnicity determines which OS marker will impact BP variation implying race/ethnicity differences in OS-related mechanisms of CVD.

Brain Natriuretic Hormone Predicts Stress-Induced Alterations in Diastolic Function

Background:Mental stress (MS) reduces diastolic function (DF) and may lead to congestive heart failure with preserved systolic function. Whether brain natriuretic hormone (brain natriuretic peptide [BNP]) mediates the relationship of MS with DF is unknown. Methods:One hundred sixty individuals aged 30 to 50 years underwent 2-hour protocol of 40-minute rest, videogame stressor and recovery. Hemodynamics, pro-BNP samples and DF indices were obtained throughout the protocol. Separate regression analyses were conducted using rest and stress E/A, E′ and E/E′ as dependent variables. Predictor variables were entered into the stepwise regression models in a hierarchical fashion. At the first level, age, sex, race, height, body mass index, pro-BNP and left ventricular mass (LVM) were permitted to enter the models. The second level consisted of systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR). The final level contained cross-product terms of race by SBP, DBP and HR. Results:E/A ratio was lower during stress compared to rest and recovery (P < 0.01). Resting E/A ratio was predicted by a regression model of age (−0.31), pro-BNP (0.16), HR (−0.40) and DBP (−0.23) with an R2 = 0.33. Stress E/A ratio was predicted by age (−0.24), pro-BNP (0.08), HR (−0.38) and SBP (−0.21) with total R2 = 0.22. Resting E′ model consisted of age (−0.22), pro-BNP (0.26), DBP (−0.27) and LVM (−0.15) with an R2 = 0.29. Stress E′ was predicted by age (−0.18), pro-BNP (0.35) and LVM (−0.18) with an R2 = 0.18. Resting E/E′ was predicted by race (0.17, B > W) and DBP (0.24) with an R2 = 0.10. Stress E/E′ consisted of pro-BNP (−0.36), height (−0.26) and HR (−0.21) with an R2 = 0.15. Conclusions:pro-BNP predicts both resting and stress DF, suggesting that lower BNP during MS may be a marker of diastolic dysfunction in apparently healthy individuals.

UTILITY AND COST ANALYSIS OF THE D-DIMER ASSAY IN DIAGNOSIS OF PULMONARY EMBOLISM USING COMPUTERIZED TOMOGRAPHIC ANGIOGRAPHY IN THE EMERGENCY DEPARTMENT

Methods: We conducted a retrospective analysis of patients who underwent CTAV in the Emergency Department at the Medical College of Georgia from 08/04 to 07/05. We included 359 consecutive patients who had CTAV for suspected VTE based on positive DD (Group1) or clinical suspicion (Group 2). We reviewed available history, physical examination and investigations for VTE. The modified Well’s score was used to subdivide the groups into high Well’s (score >4) and low Well’s (score ≤4). Actual billed costs were used for cost analysis. The primary objective was to compare the cost per positive diagnosis. Subgroup analysis was performed for both cost and yield.