Thomas C. Hilton

Intravenous adenosine : continuous infusion and low dose bolus administration for determination of coronary vasodilator reserve in patients with and without coronary artery disease

To assess the use of adenosine as an alternative agent for determination of coronary vasodilator reserve, hemodynamics and coronary blood flow velocity were measured at rest and during peak hyperemic responses to continuous intravenous adenosine infusion (50, 100 and 150 micrograms/kg per min for 3 min) and intracoronary papaverine (10 mg) in 34 patients (17 without [group 1] and 17 with [group 2] significant left coronary artery disease), and in 17 patients (11 without and 6 with left coronary artery disease) after low dose (2.5 mg) intravenous bolus injection of adenosine. The maximal adenosine dose did not change mean arterial pressure (-10 +/- 14% and -6 +/- 12% for groups 1 and 2, respectively) but increased the heart rate (15 +/- 18% and 13 +/- 16, respectively). For continuous adenosine infusions, mean coronary flow velocity increased 64 +/- 104%, 122 +/- 94% and 198 +/- 59% and 15 +/- 51%, 110 +/- 95% and 109 +/- 86% in groups 1 and 2, respectively for each of the three doses. Mean coronary flow velocity increased significantly after 100 and 150 micrograms/kg of adenosine and 10 mg of intracoronary papaverine (48 +/- 25, 52 +/- 19 and 54 +/- 21 cm/s, respectively; all p less than 0.05 vs. baseline) and was significantly higher than in group 2 (37 +/- 24, 32 +/- 16, 41 +/- 23 cm/s; all p less than 0.05 vs. group 1). The coronary vasodilator reserve ratio (calculated as the ratio of hyperemic to basal mean flow velocity) for adenosine and papaverine was 2.94 +/- 1.50 and 2.94 +/- 1.00, respectively, in group 1 and was significantly and similarly reduced in group 2 (2.16 +/- 0.81 and 2.38 +/- 0.78, respectively; both p less than 0.05 vs. group 1). Low dose bolus injection of adenosine increased mean velocity equivalently to that after continuous infusion of 100 micrograms/kg, but less than after papaverine. There was a strong correlation between adenosine infusion and papaverine for both mean coronary flow velocity and coronary vasodilator reserve ratio (r2 = 0.871 and 0.325; SEE = 0.068 and 0.189, respectively; both p less than 0.0005). No patient had significant arrhythmias or prolongation of the corrected QT (QTc) interval with adenosine, but papaverine increased the QT (QTc) interval from 445 +/- 44 to 501 +/- 43 ms (p less than 0.001 vs. both maximal adenosine and baseline) and produced nonsustained ventricular tachycardia in one patient.(ABSTRACT TRUNCATED AT 400 WORDS)

Potential Cost Effectiveness of Initial Myocardial Perfusion Imaging for Assessment of Emergency Department Patients With Chest Pain

Previous investigations have confirmed the diagnostic and predictive usefulness of initial single-photon emission computed tomography (SPECT) myocardial perfusion imaging using technetium-99m sestamibi in the evaluation of emergency department patients with chest pain. Patients with a normal SPECT perfusion scan performed during chest pain have an excellent short-term prognosis, and may be candidates for expeditious cardiac evaluation or outpatient management. However, there are limited data regarding the cost effectiveness of this technique. This analysis models the potential cost effectiveness of this procedure. In the current investigation we compared 2 model strategies for management of emergency department patients with typical chest pain and a normal or nondiagnostic electrocardiogram (ECG). In 1 model strategy, (the technetium-99m sestamibi SPECT myocardial perfusion imaging [SCAN] strategy), the decision whether to admit or discharge a patient from the emergency department is based on results of initial technetium-99m sestamibi SPECT myocardial imaging. Patients with normal scans are discharged; others are admitted. In the second model strategy, (the NO SCAN strategy), the decision whether or not to admit a patient is based on a combination of clinical and electrocardiographic variables. Patients with > or = 3 cardiac risk factors or an abnormal ECG are admitted; others are discharged. Adverse cardiac events were prospectively defined as cardiac death, nonfatal myocardial infarction, or the need for acute coronary intervention. Costs were assigned using data derived from 102 patients who underwent SPECT myocardial perfusion imaging and an additional 107 emergency department patients with ongoing chest pain who either underwent or were eligible for initial SPECT myocardial perfusion imaging. Mean (+/- SE) costs were highest among hospital admitted patients who experienced an adverse cardiac event (

Prognostic value of dipyridamole thallium-201 imaging in elderly patients☆

21,375 +/-

Prognostic significance of exercise thallium-201 testing in patients aged ≥70 years with known or suspected coronary artery☆

2,733) and lowest in patients discharged from the emergency department (

Effects of left ventricular hypertrophy on the signal-averaged electrocardiogram

715 +/- 71). Mean costs per patient of the SCAN strategy and NO SCAN strategy were

Acute mitral regurgitation with cardiogenic shock in a patient with hypertrophic cardiomyopathy: A critical management dilemma

5,019 versus

Determination of perioperative cardiac risk by adenosine thallium-201 myocardial imaging

6,051, respectively. These results were stable in a sensitivity analysis across a range of costs and predictive values. Thus, the SCAN model strategy for initial management of emergency department patients with typical ongoing angina and a normal or nondiagnostic ECG using initial myocardial perfusion imaging with technetium-99m sestamibi appears to be safe, accurate, and potentially cost effective. Validation of these preliminary retrospective observations will require further prospective investigation.

The prognosis in stable and unstable angina.

The prognostic value of intravenous dipyridamole myocardial perfusion imaging has not been studied in a large series of elderly patients. Patients greater than or equal to 70 years of age with known or suspected coronary artery disease were evaluated to determine the predictive value of intravenous dipyridamole thallium-201 imaging for subsequent cardiac death or nonfatal myocardial infarction. Of the 348 patients, 207 were symptomatic and 141 were asymptomatic; 52% of the asymptomatic group had documented coronary artery disease. During 23 +/- 15 months of follow-up, there were 52 cardiac deaths, 24 nonfatal myocardial infarctions and 42 revascularization procedures (percutaneous transluminal coronary angioplasty in 20; coronary artery bypass surgery in 22). Clinical univariate predictors of a cardiac event included previous myocardial infarction, congestive heart failure symptoms, hypercholesterolemia and diabetes (all p less than 0.05). The presence of a fixed, reversible or combined thallium-201 defect was significantly associated with the occurrence of cardiac death or myocardial infarction during follow-up (p less than 0.05). Cardiac death or nonfatal myocardial infarction occurred in only 7 (5%) of 150 patients with a normal dipyridamole thallium-201 study (p less than 0.001). Stepwise logistic regression analysis of clinical and radionuclide variables revealed that an abnormal (reversible or fixed) dipyridamole thallium-201 study was the single best predictor of cardiac events (relative risk 7.2, p less than 0.001). As has been demonstrated in younger patients, previous myocardial infarction (relative risk 1.8, p less than 0.001) and symptoms of congestive heart failure at presentation (relative risk 1.6, p = 0.02) were also significant independent clinical predictors of cardiac death or myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Intralobar pulmonary sequestration with nutrient systemic arterial flow from multiple coronary arteries

Abstract The prognostic value of exercise thallium-201 myocardial perfusion imaging has not been studied in an elderly (aged ≥70 years) population. Retrospective analysis of 120 consecutive elderly patients undergoing Bruce protocol exercise stress with quantitative planar thallium-201 scintigraphy, followed clinically for a mean of 36 ± 12 months after testing, revealed a 10% cardiac event rate (6 cardiac deaths from arrhythmia or congestive heart failure, and 5 fatal and 1 nonfatal myocardial infarction). There were no exercise stress-related complications. Survival without cardiac events was associated with greater exercise duration (5.6 ± 2.4 vs 3.1 ± 2.4 minutes; p 15%, respectively.

Delayed rupture of tricuspid papillary muscle following blunt chest trauma

Abstract Signal-averaged electrocardiography (SAECG) has made possible the identification of late potentials in patients at risk of developing malignant ventricular arrhythmias. 1–9 Late potentials have been shown to predict sudden cardiac death, 3,4 clinical ventricular tachycardia, 1,3–6 and ventricular tachycardia that is inducible with programmed electrical stimulation. 8–10 Sudden cardiac death 11,12 and ventricular arrhythmias 13–19 are more prevalent in patients with echocardiographic left ventricular (LV) hypertrophy. Late potentials might be useful in identifying a subgroup of patients with LV hypertrophy who are at high risk to experience clinical ventricular tachycardia or sudden cardiac death. However, patients with LV hypertrophy may have intraventricular conduction disturbances and repolarization abnormalities that may interfere with the ability of SAECG to accurately detect late potentials. To evaluate the use of SAECG in patients with LV hypertrophy, we examined 58 patients with SAECG, echocardiography and programmed electrical stimulation. In this study, we compare the clinical characteristics, SAECG findings and electrophysiology results of a group of patients with echocardiographic LV hypertrophy to a group of patients without echocardiographic LV hypertrophy.