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R C Hendel

Publications and source records attributed to R C Hendel.

At least 37 records · Page 2Linked to original sources
PubMed1995

Sex differences in perioperative and long-term cardiac event-free survival in vascular surgery patients. An analysis of clinical and scintigraphic variables.

BACKGROUND: Little information is available regarding the occurrence of perioperative and late cardiac events in women with vascular disease. The current study was performed to examine whether sex-specific differences exist in these outcomes in a large population of vascular surgery patients and to determine the value of clinical and dipyridamole thallium variables in predicting myocardial infarction and cardiac death. METHODS AND RESULTS: Preoperative dipyridamole thallium imaging was performed in 567 vascular surgery patients, including 380 men and 187 women. The incidence of nonfatal myocardial infarction and cardiac death was noted during the perioperative period and during a follow-up period of 50 +/- 5 months. Fixed and reversible thallium perfusion abnormalities were more common in men than in women (P < .001 and P = .004, respectively). Perioperative cardiac event rates were similar in men and women, 8.4% and 7.5%, respectively (P = .07). A transient thallium defect was associated with an increased risk of cardiac events by 3.9-fold in men (CI, 1.5 to 10.2) and 5.5-fold in women (CI, 1.4 to 22). Various clinical factors also were predictive of events but demonstrated substantial sex differences. For example, dipyridamole-induced ST-segment depression was strongly associated with perioperative events in men but not in women. There were 22 nonfatal myocardial infarctions and 29 cardiac deaths in men during the follow-up period, with comparable event rates noted for women. Cardiac event-free survival rates also were similar for men and women (P = .40). Multivariate analysis demonstrated that a history of heart failure was an important prognostic variable for both sexes, as was a fixed thallium defect. Significant sex differences in the predictive value of other clinical factors for late cardiac events was apparent. CONCLUSIONS: The present study demonstrates that (1) thallium perfusion defects are more common in men; (2) transient thallium defects are associated with perioperative myocardial infarction and cardiac death in both sexes; (3) long-term survival rates after vascular surgery are similar between men and women; (4) a fixed perfusion defect is predictive of late cardiac events in women, with a trend noted in men; and (5) sex-specific differences were noted with regard to the prognostic value of various clinical risk factors. Therefore, dipyridamole thallium plays a significant role in the assessment of perioperative and long-term prognosis for both male and female vascular surgery patients. On the basis of these observations, modifications in risk stratification based on sex may be appropriate for men and women with vascular disease.

Aged↗
PubMed1995

Myocardial perfusion imaging with 99mTc tetrofosmin. Comparison to 201Tl imaging and coronary angiography in a phase III multicenter trial. Tetrofosmin International Trial Study Group.

BACKGROUND: Our objective was to compare the sensitivity and specificity of tetrofosmin, a new 99mTc-labeled myocardial perfusion imaging agent for the detection of myocardial perfusion abnormalities, with those of 201Tl and coronary angiography. Our hypothesis was that same-day stress/rest tetrofosmin imaging could provide data comparable to those of 201Tl imaging. Myocardial perfusion imaging plays an important role for the evaluation of coronary artery disease. Newer 99mTc-labeled agents offer several advantages over 201Tl, the conventional myocardial perfusion imaging agent. Tetrofosmin is a new 99mTc-labeled agent with promising results in preliminary studies. METHODS AND RESULTS: Two hundred fifty-two patients with suspected coronary artery disease were enrolled in 10 centers in the United States and Europe. All patients underwent exercise and rest myocardial perfusion imaging with 99mTc-tetrofosmin using two separate injections of the radiotracer 4 hours apart on the same day. Planar images were obtained in three standard views 15 to 60 minutes after radiotracer injection. Patients also underwent standard exercise and redistribution planar 201Tl imaging within 2 weeks of tetrofosmin imaging. In addition, 58 healthy subjects with low likelihood of coronary artery disease underwent exercise and rest tetrofosmin imaging. Coronary angiograms were available in 181 patients with suspected coronary artery disease. All radionuclide images were processed in the central core laboratory and interpreted blindly by a panel of four experienced readers. 201Tl images and tetrofosmin images were read separately. Discrepancies were resolved by consensus. The workload, peak heart rate, and double products were comparable during exercise for both imaging agents. Technically acceptable paired 201Tl and tetrofosmin images were available in 224 of 252 patients. Tetrofosmin images were generally of good quality, with low extracardiac activity, and easy to interpret. Patients were categorized as showing normal, ischemia, infarction, or mixture with each imaging modality. Precise concordance for each of these categories was 59.4% (kappa = 0.44; 95% CI, 0.35 to 0.53). When patients were categorized as normal or abnormal, the concordance was 80.4% (kappa = 0.55; 95% CI, 0.43 to 0.67). When each of five anatomic territories (septal, anterior, inferior, lateral, and apical) was categorized as normal versus abnormal, the concordance varied from 81% to 90%. When similar comparison was made for the specific category of abnormality, the concordance was 64% to 84%. When coronary angiography was used as the criterion, the sensitivity and positive and negative predictive accuracy of tetrofosmin and 201Tl were comparable. The normalcy rate of tetrofosmin images in the healthy subjects with low likelihood of coronary artery disease was 97%. CONCLUSIONS: 99mTc tetrofosmin is a new myocardial imaging agent with favorable imaging characteristics with results comparable to those of 201Tl.

Adult↗
PubMed1995

Comparative early and late cardiac morbidity among patients requiring different vascular surgery procedures.

PURPOSE: The evaluation of coronary artery disease (CAD) in patients undergoing vascular surgery can provide information with respect to perioperative and long-term risk for CAD-related events. However, the extent to which the required surgical procedure itself imparts additional risk beyond that dictated by the presence of CAD determinants remains in question. The purpose of this study was to quantify the relative contributions of specific vascular procedures and CAD markers on perioperative and long-term cardiac risk. METHODS: The study cohort comprised 547 patients undergoing vascular surgery from two medical centers who underwent clinical evaluation, dipyridamole thallium testing, and either aortic (n = 321), infrainguinal (n = 177), or carotid (n = 49) vascular surgery between 1984 and 1991. Perioperative and late cardiac risk of fatal or nonfatal myocardial infarction (MI) was compared for the three procedures before and after adjustment for the influence of comorbid factors. These adjusted estimates may be regarded as the component of risk because of type of surgery. RESULTS: Perioperative MI occurred in 6% of patients undergoing aortic and carotid artery surgery, and in 13% of patients undergoing infrainguinal procedures (p = 0.019). Significant (p < 0.05) predictors of MI were history of angina, fixed and reversible dipyridamole thallium defects, and ischemic ST depression during testing. Although patients undergoing infrainguinal procedures exhibited more than twice the risk for perioperative MI compared with patients undergoing aortic surgery (relative risk: 2.4[1.2 to 4.5, p = 0.008]), this value was reduced to insignificant levels (1.6[0.8 to 3.2, p = 0.189]) after adjustment for comorbid factors. There was little change in comparative risk between carotid artery and aortic procedures before (1.0[0.3 to 3.6, p = 0.95]) or after (0.6[0.2 to 2.3, p = 0.4]) covariate adjustment. The 4-year cumulative event-free survival rate was 90% +/- 2% for aortic, 74% +/- 5% for infrainguinal, and 78% +/- 7% for carotid artery procedures (p = 0.0001). Predictors of late MI included history of angina, congestive heart failure, diabetes, fixed dipyridamole thallium defects, and perioperative MI. Patients undergoing infrainguinal procedures exhibited a threefold greater risk for late events compared with patients undergoing aortic procedures (relative risk: 3.0[1.8 to 5.1, p = 0.005]), but this value was reduced to 1.3(0.8 to 2.3, p = 0.32) after adjustment. Long-term risk among patients undergoing carotid artery surgery was less dramatically altered by risk factor adjustment. CONCLUSION: In current practice, among patients referred for dipyridamole testing before operation, observed differences in cardiac risk of vascular surgery procedures may be primarily attributable to readily identifiable CAD risk factors rather than to the specific type of vascular surgery. Thus the cardiac and diabetic status of patients should be given careful consideration whenever possible, regardless of surgical procedure to be performed.

Aged↗
PubMed1995

Myocardial infarction in women.

The leading cause of death in the United States is cardiovascular disease, regardless of gender. Women will more often have angina preceding their first myocardial infarct, but have more unrecognized infarctions than men. Women will be older, have more concomitant disease and present later in the course of their acute myocardial infarction. Although myocardial infarction may have similar clinical presentations in men and women, there are some important differences such as an increased incidence of non Q-wave myocardial infarctions in women, and the higher rate of complication and immortality from a myocardial infarct. Women develop less collateral cardiac vessels, which may explain the increased rate of hemodynamic complications after a myocardial infarct. Both early and late survival rates are also affected by the advanced mean age of women when they do present with a myocardial infarct. There is less data regarding treatment modalities based upon gender differences but in general, it appears that women benefit from established treatment modalities in the acute setting and subsequent to the event. It has been determined that there are epidemiologic differences, but pathophysiologic and clinical factors specific to women in this setting have yet to be determined.

Female↗
PubMed1994

Single-photon perfusion imaging for the assessment of myocardial viability.

The identification of viable myocardium is an important consideration for patient selection prior to interventional procedures, especially in patients with severe left ventricular dysfunction. Myocardial perfusion imaging may reflect viability, because tracer uptake requires adequate perfusion, cellular integrity and metabolic function. The underestimation of myocardial viability noted with traditional stress and redistribution thallium imaging has lead to the development of alternative protocols to detect viable myocardium, such as late (24-hr) imaging and the thallium reinjection method. Rest-redistribution thallium imaging may be a useful procedure for predicting recovery of ventricular function following revascularization. Quantitative analysis of thallium activity provides important information, because mild or moderate defects are usually metabolically active as determined by PET. Administration of adjunct medications, such as ribose or nitroglycerin, can increase the detection of reversible perfusion abnormalities. Technetium-99m perfusion agents offer great promise for perfusion imaging, but their role in the detection of myocardial viability is not well defined. Underestimation of myocardial viability has been described with 99mTc-sestamibi scintigraphy; however, use of quantitative perfusion image analysis or the addition of functional data provided by gated tomography or first-pass imaging may enhance the assessment of viability. Although the optimal method for the detection of myocardial viability with single-photon agents is not apparent, current methods have substantially improved discrimination between nonviable and viable myocardium. In certain instances, however, metabolic imaging with single-photon fatty acid analogs or positron-emitting radionuclides may be necessary.

Coronary Disease↗
PubMed1993

Rapid redistribution of teboroxime.

Teboroxime, a new technetium-99m-labeled myocardial perfusion tracer, possesses rapid myocardial kinetics. Whereas this agent is routinely imaged after separate stress and rest injections, experimental data suggest that teboroxime may rapidly redistribute in the myocardium. Accordingly, we assessed 68 exercise teboroxime scintigrams in which immediate poststress, early delay (5 minutes) and rest images were acquired. Studies were categorized visually as ischemia, infarct or normal based on conventional stress-rest comparison. They were then evaluated for rapid teboroxime redistribution by comparing the stress and early delay images. Quantitative analysis was then performed on 537 myocardial segments. Segments were grouped as ischemia, infarct or normal based on stress-rest comparison, and the degree of normalization of stress-induced defects in the early delay images was determined for each group. Rapid teboroxime redistribution was observed in 20 of 46 scintigrams (48%) considered ischemic, and in 2 of 7 and 2 of 15 scintigrams deemed infarct and normal, respectively. The mean segmental intensity ratio (defined relative to the opposite segment) improved from 0.79 at stress to 0.88 at early delay (p < 0.005) in the group with ischemia and from 0.83 to 0.87 in the group with infarction. The most likely explanation for rapid redistribution of teboroxime is differential washout from the myocardium between areas of disparate flow. It is concluded that rapid redistribution of teboroxime occurs within 5 minutes of a stress injection, giving rise to potentially useful clinical information. Thus, teboroxime imaging should be completed expeditiously to detect areas of relative hypoperfusion.

Exercise Test↗
PubMed1993

Comparison of teboroxime and thallium for the reversibility of exercise-induced myocardial perfusion defects.

To determine the optimal technique for the scintigraphic detection of exercise-induced myocardial perfusion defects, we compared teboroxime scanning to both stress/redistribution thallium imaging and the thallium reinjection method following exercise in 35 patients. The overall concordance for the presence of a perfusion defect between teboroxime and thallium scanning was 91% (p < 0.01) and 89% when teboroxime was compared with stress/reinjection thallium imaging (p < 0.01). More segments per scan with fixed defects were observed with redistribution imaging than with teboroxime or thallium reinjection (2.9 vs 2.0 vs 1.9; p < 0.02). Additionally, more transient defects were present with teboroxime than thallium, but less than with reinjection imaging. One half of the 52 fixed perfusion abnormalities on stress/redistribution thallium imaging demonstrated reversibility with both teboroxime imaging and thallium reinjection scanning, but less than 50% of these segments were concordant. Teboroxime allows for improved detection of reversible perfusion defects compared with stress/redistribution thallium scanning, but more ischemia is noted with thallium reinjection. The variation in the detection of segmental ischemic defects between teboroxime scintigraphy and thallium reinjection scanning probably reflects different physiologic properties and imaging protocols of these perfusion agents.

Aged↗
PubMed1993

Comparison of 3- versus 6-minute infusions of adenosine in thallium-201 myocardial perfusion imaging.

Adenosine thallium stress testing has a demonstrated utility in the detection of coronary artery disease. The optimal dose for diagnostic efficacy with minimal side effects has not been critically evaluated. A randomized 3- and 6-minute infusion of adenosine (140 micrograms/kg/min) was performed in 11 subjects. Subjects reported more side effects during the 6-minute infusion protocol (p < 0.05). Hemodynamic changes were not different during either infusion duration. All dysrhythmias began within 2 minutes and therefore the duration of the infusion did not influence their occurrence. Segmental comparison of the stress images demonstrated an 89% agreement. Delayed scans demonstrated a 79% agreement. There was a higher incidence of redistribution following the 6-minute infusion (p = 0.014). We conclude that when side effects necessitate the discontinuation of a 6-minute adenosine infusion, a diagnostic test can still be achieved if 2 to 3 minutes of adenosine have been administered before the thallium injection; however, the amount of viable myocardium may be underestimated.

Adenosine↗
PubMed1992

Prediction of late cardiac events by dipyridamole thallium imaging in patients undergoing elective vascular surgery.

Dipyridamole thallium scintigraphy has previously been shown to have prognostic value in the preoperative assessment of patients scheduled to undergo vascular surgery, but its effect on the long-term outcome is less well-defined. In the largest series to date, dipyridamole thallium scanning was performed in 360 patients before elective vascular surgery and survivors were followed for a mean of 31 months. In the 327 patients who underwent vascular surgery, operative death and nonfatal myocardial infarction occurred in 4.9 and 6.7%, respectively. A cardiac event (nonfatal myocardial infarction or cardiac death) occurred in 14.4% of patients with a transient thallium defect, as opposed to 1% with a normal scan (p < 0.001). Logistic regression analysis revealed that the best predictor of a perioperative event was the presence of a reversible thallium defect, elevating the risk by 4.3-fold. Late cardiac events occurred in 53 (15.2%) surgical survivors or nonsurgically treated patients. Patients with a fixed perfusion abnormality had a 24% late event rate, compared with 4.9% in those with a normal dipyridamole thallium study (p < 0.01). Cox analysis demonstrated that a fixed thallium defect was the strongest factor for predicting a late event and increased the relative risk by almost fivefold. A history of congestive heart failure was the only significant variable that contributed additional value to that of a fixed defect alone. Life-table analysis confirmed the strong relation of a fixed defect to cardiac event free survival (p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Focal myocardial injury following blunt chest trauma: a comparison of indium-111 antimyosin scintigraphy with other noninvasive methods.

The diagnosis of myocardial contusion is often difficult, as traditional methods such as serial electrocardiograms, cardiac enzyme (creatine kinase [CK-MB]) analysis, and echocardiography lack sensitivity and specificity. Recent reports have shown that 111In labelled antimyosin scanning has high sensitivity for detecting cardiac injury. However, no prior studies have been reported for antimyosin imaging with patients suspected of sustaining a cardiac contusion. Accordingly, 17 patients with severe multisystem trauma (intrathoracic vascular injury in eight patients, pneumothorax and pulmonary contusion in 13) underwent antimyosin scintigraphy, echocardiography, 12-lead electrocardiograms, and CK-MB determinations. Arrhythmias were noted in seven patients, four of whom died. All patients has elevated CK levels but CK-MB isoenzyme was greater than 4% in only three. Abnormal ST segments were noted in nine subjects, only one of whom had CK-MB elevation. Echocardiography revealed pericardial effusions in four patients but was technically suboptimal in 53% of the studies. Blinded interpretation of the antimyosin scans revealed only one with focal myocardial uptake; this same patient had the only discrete wall motion abnormality on the echocardiogram and also had ST depression with ectopy but normal CK-MB. Thus in patients with suspected myocardial contusion, echocardiography is frequently limited technically and the electrocardiogram and CK analysis appear to lack diagnostic accuracy. In contrast, monoclonal antimyosin imaging may be performed in patients with trauma without limitation and yields results that are concordant with echocardiograms. In patients with suspected myocardial contusion, focal antimyosin uptake is uncommon despite severe thoracic injury, which suggests that extensive myocardial necrosis is not the primary method of injury.

Adult↗
PubMed1992

Planar myocardial perfusion imaging with technetium-99m-teboroxime: comparison by vascular territory with thallium-201 and coronary angiography.

Myocardial perfusion agents labeled with 99mTc offer improved physical imaging properties compared to 201TI. Teboroxime is a new 99mTc-labeled compound for myocardial perfusion imaging that shows a high myocardial extraction and rapid clearance. Sixty-seven patients underwent planar teboroxime imaging with a rapid acquisition protocol. Agreement of teboroxime and 201TI for the presence or absence of disease occurred in 56/65 patients (86%). There was agreement (normal or abnormal) between the two agents in 156/195 vessels (80%) and 457/585 segments (78%). When abnormal segments (ischemia or infarction) were compared, teboroxime showed significantly more ischemic segments (89/135, 66%) than did 201TI (73/135, 54%, p < 0.05). Teboroxime offers accuracy comparable to 201TI for the diagnosis of coronary artery disease and may improve the detection of ischemic or viable myocardium. In addition, its rapid myocardial clearance permits stress/rest imaging in 60-90 min.

Coronary Angiography↗
PubMed1992

Dipyridamole-thallium scintigraphy predicts perioperative and long-term survival after major vascular surgery.

The purpose of this study was to evaluate the ability of dipyridamole-thallium scintigraphy to predict perioperative and late cardiac events after peripheral vascular operations. A total of 262 patients had dipyridamole-thallium scintigraphy before 87 infrainguinal reconstructions, 108 abdominal aortic aneurysm operations, and 67 aortobifemoral bypass grafts that were placed for occlusive disease. Follow-up extended to 5 years (mean, 31.1 months). Logistic regression analysis selected dipyridamole-thallium scintigraphy redistribution as the best predictor of perioperative events. Fixed defects were not predictive. A Cox proportional hazards model for a variety of clinical risk factors and scan parameters identified fixed defects and a history of congestive heart failure as the strongest predictors of late cardiac events. The presence of greater than 1 or 2 fixed segments were the best predictors in patients with an abnormal scan; redistribution did not predict late events. The risk of combined perioperative or late cardiac events was 29% for infrainguinal, 19% for abdominal aortic aneurysm, and 7.5% for aortobifemoral operations. Life-table analysis showed that after a cluster of perioperative events that occurred primarily in patients with dipyridamole-thallium scintigraphy redistribution, most of the late cardiac morbidity and deaths occurred in patients with fixed defects.

Aged↗
PubMed1991

Prognosis following interventional therapy for acute myocardial infarction: utility of dipyridamole thallium scintigraphy.

A variety of methods for risk stratification after acute myocardial infarction have been successfully employed, however, little attention has been focused on patients who have received reperfusion therapy. The present report examines the utility of dipyridamole thallium scintigraphy in the prediction of late cardiac death or recurrent myocardial infarction in patients who have received thrombolytic therapy. Prospectively, 71 patients who presented with myocardial infarction and were treated with recombinant tissue plasminogen activator (and frequently percutaneous transluminal coronary angioplasty) were enrolled in the study. The primary end points during the follow-up period of nearly 2 years were recurrent infarction or death, which occurred in 10 patients. Although cardiac events were significantly related to either the performance of late myocardial revascularization or the presence of a residual coronary artery stenosis at discharge, no scintigraphic variable was found to be predictive of myocardial infarction or death. Thus, this report is the first to suggest limitation of scintigraphic techniques with regard to prognostic value in myocardial infarction survivors treated with reperfusion techniques. This selected population may have physiologic differences as compared with post-infarction studies performed before the advent of thrombolytic agents. Caution is therefore advised in extrapolating results of earlier reports to the ever increasing percentage of patients receiving recannalization therapy.

Adult↗
PubMed1990

Prognostic value of dipyridamole thallium scintigraphy for evaluation of ischemic heart disease.

Exercise testing alone or in combination with thallium scintigraphy has significant prognostic value. In contrast, dipyridamole thallium imaging is not dependent on patients achieving adequate levels of exercise, but no long-term prognostic studies have been reported. Accordingly, imaging results of 516 consecutive patients referred for dipyridamole thallium studies were correlated with subsequent cardiac events, death (n = 23) and myocardial infarction (n = 43) over a mean follow-up period of 21 months. Patients with a history of congestive heart failure, prior myocardial infarction, diabetes mellitus or abnormal scans were significantly more likely to have a cardiac event (p less than 0.03). With use of logistic regression analysis, an abnormal scan was an independent and significant predictor of subsequent myocardial infarction or cardiac death and increased the relative risk of any event more than threefold. The presence of redistribution on thallium scanning further increased the risk of a cardiac event. Survival analysis demonstrated a significant difference between patients with an abnormal or normal thallium scan over a 30 month period. In conclusion, dipyridamole thallium scintigraphy demonstrates prognostic value in a large unselected population and may be an adequate clinical alternative to physiologic exercise testing in the evaluation of coronary heart disease.

Aged↗
PubMed1990

Diagnostic value of a new myocardial perfusion agent, teboroxime (SO 30,217), utilizing a rapid planar imaging protocol: preliminary results.

Technetium-99m-labeled agents have advantages over thallium-201 in terms of photon statistics, cost and clinical availability. They have been suggested as an alternative to thallium for myocardial perfusion imaging. Teboroxime is a new boronic acid adduct of technetium dioxime (BATO) compound that demonstrates favorable characteristics in preliminary studies. With use of a novel (seated) patient positioning technique and a rapid dynamic acquisition protocol, 30 patients underwent planar imaging with teboroxoime while at rest and after maximal treadmill exercise. Postexercise scans were completed in an average time (mean +/- SD) of 4.4 +/- 1.6 min, with 4.8 +/- 1.5 min for the views at rest. These results were compared with coronary arteriography or thallium scintigraphy after treadmill exercise, or both. Diagnostic agreement (abnormal versus normal) was present in 28 of the 30 patients (p less than 0.001). Regarding physiologic assessment as compared with thallium scintigraphy, the finding of infarction and ischemia was concordant in 89% and 86% of patients, respectively. This report describes the initial use of teboroxime with a rapid dynamic planar imaging technique, resulting in a high correlation with exercise thallium scintigraphy. Delayed postexercise images obtained 5 to 10 min after exercise demonstrated rapid disappearance of exercise-induced defects noted on the initial (0 to 5 min) postexercise views. The rapid differential washout with teboroxime has not been previously described and the possible clinical significance is discussed.

Adult↗
PubMed1990

Myocardial infarction in women.

Cardiovascular disease is the leading cause of mortality in the United States regardless of gender. Women infrequently present with myocardial infarction as the initial presentation of coronary heart disease and have unrecognized infarctions more frequently than men. Myocardial infarction in women has a similar clinical presentation as in men, with the exception of an increased incidence of non-Q wave myocardial infarctions. Complications of acute infarction in women are probably similar although the majority of data has been drawn from studies involving predominantly men. Women do however experience more strokes and have less postinfarction pericarditis than their male counterparts. Left ventricular function remains the key prognostic determinant in both sexes. Recurrent infarction is increased in women with resultant elevated mortality rates. However, complex ventricular ectopy following myocardial infarction is not predictive of cardiovascular mortality in women. Early and late survival is decreased in women, an effect probably related to the increase in mean age of women as compared with men. Overall, gender distinctions are not usually made in the majority of studies involving myocardial infarction. As epidemiologic, pathophysiologic and clinical factors may be different regarding heart disease in women, further research in this important area is warranted.

Female↗