Forearm blood flow response to acute exercise in obese and non-obese males.

Chronic exercise is thought to improve endothelium-dependent vasodilation; however, few studies have evaluated the effects of acute exercise on microvascular vasodilatory capacity (MVC). Moreover, no studies have compared MVC responses in obese and non-obese individuals following acute exercise. To evaluate MVC, utilizing forearm blood flow (FBF) and excess blood flow (EBF) before and up to 48 h after a single exercise bout to elicit peak oxygen consumption (VO2 peak) in obese and non-obese males. Twelve obese (37.0 ± 1.1 kg/m(2)) and 12 non-obese (21.9 ± 0.3 kg/m(2)) males volunteered to participate. FBF measures, before and during reactive hyperemia (RH), were obtained prior to (PRE-E), immediately after (POST-E), and at 1 (POST-1), 2 (POST-2), 24 (POST-24), and 48 (POST-48) hours after exercise. EBF, was calculated as the difference between FBF, before and during RH. Blood samples were obtained to evaluate the response of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α), which are potential modifiers of MVC. FBF before and during RH were significantly (P < 0.05) increased in both groups POST-E. The EBF magnitude of change from PRE-E was significantly (P < 0.05) elevated in non-obese when compared with obese males. Although not related to MVC, concentrations of IL-6 significantly decreased between POST-2 and POST-24 in both groups. An acute bout of exercise designed to elicit VO2 peak significantly increased forearm MVC in non-obese and obese males, although the magnitude of change in EBF from PRE-E to POST-E was greater in non-obese males.

The influence of sex on the relationship between heart rate recovery and other cardiovascular risk factors in apparently healthy subjects.

Heart rate recovery (HRR) is an important indicator of cardiovascular health. The purpose of the present investigation is to examine the influence of sex on the relationship between HRR and other markers of cardiovascular health. Two hundred and seventy-five apparently healthy subjects participated in this study. Subjects underwent cardiopulmonary exercise testing (outcome measures: VO(2max) and HRR 1 and 2 min into recovery), lipid analysis, measurement of resting systolic and diastolic blood pressure and measurement of aortic wave velocity (AWV in m/s) via magnetic resonance. HRR both at 1 min (HRR(1)) and at 2 min (HRR(2)) were higher in males. In general, the correlation between HRR(1) and other measures of interest was weaker than that found with HRR(2) in both male and female subjects. With respect to HRR(2), the relationship with other measures of interest was stronger in the female subgroup. Specific to arterial stiffness, the correlation between HRR(2) and AWV was -0.33 and -0.46 (P<0.001 for both) in male and female subgroups, respectively. The results of the present study indicate that both gender and the timing of HRR measurement influence its relationship with other important cardiovascular risk factors.

Comparison between 2-dimensional echocardiography and myocardial perfusion imaging in the emergency department in patients with possible myocardial ischemia.

BACKGROUND: Accurate identification of patients at high risk for acute coronary syndromes among those seen in the emergency department (ED) with possible myocardial ischemia and nonischemic electrocardiograms is problematic. Both 2-dimensional echocardiography and myocardial perfusion imaging with technetium-99m sestamibi can identify patients at low and high risk; however, comparative studies are lacking. METHODS AND RESULTS: Patients initially considered at low or moderate risk for myocardial ischemia on the basis of the presenting history, physical examination, and electrocardiogram underwent both echocardiography and myocardial perfusion imaging within 4 hours of ED presentation. Positive echocardiography was defined as the presence of segmental wall motion abnormalities or moderate to severe global systolic dysfunction; positive perfusion imaging was defined as a perfusion defect in association with abnormal wall motion, thickening, or both. End points included MI, percutaneous transluminal coronary angioplasty, and positive stress perfusion imaging. Both imaging procedures were performed in the ED on 185 patients. Six patients had MI, and an additional 4 patients underwent percutaneous transluminal coronary angioplasty. Echocardiography and perfusion imaging were positive in all 10. Overall agreement between the 2 techniques was high (concordance 89%, kappa coefficient 0.74) in the 27 patients who had MI or underwent coronary angiography. For all patients, concordance was 89%, with a kappa coefficient of 0.66. CONCLUSIONS: Agreement between echocardiography and perfusion imaging with technetium-99m sestamibi is high when used in patients in the ED with possible myocardial ischemia. Both techniques identified patients at high risk who required admission and those who could be safely discharged directly from the ED.

Early echocardiography can predict cardiac events in emergency department patients with chest pain.

STUDY OBJECTIVE: Accurate diagnosis in emergency department patients with possible myocardial ischemia is problematic. Two-dimensional echocardiography has a high sensitivity for identifying patients with myocardial infarction (MI); however, few studies have investigated its diagnostic ability when used acutely in ED patients with possible myocardial ischemia. Therefore we investigated the ability of ED echocardiography for predicting cardiac events in patients with possible myocardial ischemia. METHODS: Echocardiography was performed within 4 hours of ED presentation in 260 patients with possible myocardial ischemia, and was considered positive if there were segmental wall motion abnormalities or the ejection fraction was less than 40%. ECGs were considered abnormal if there was an ST-segment elevation or depression of greater than or equal to 1 mm, or ischemic T-wave inversion. Cardiac events included MI and revascularization. RESULTS: Of the 260 patients studied, 45 had cardiac events (23 MI, 19 percutaneous transluminal angioplasty, 3 coronary bypass surgery). The sensitivity of echocardiography for predicting cardiac events was 91% (95% confidence interval 79% to 97%]), which was significantly higher than the ECG (40% [95% CI 27% to 55%]: P < .0001), although specificity was lower (75% [95% CI 69% to 81%] versus 94% [95% CI 90% to 97%]; P < .001). Addition of the echocardiography results to baseline clinical variables and the ECG added significant incremental diagnostic value (P < .001). With use of multivariate analysis, only male gender (P < .03, odds ratio [OR] 2.4 [1.1 to 5.3]), and a positive echocardiographic finding (P < .0001, OR 24 [9 to 65]) predicted cardiac events. Excluding patients with abnormal ECGs (N = 30) did not affect sensitivity (85%) or specificity (74%) of echocardiography. CONCLUSION: Echocardiography performed in ED patients with possible myocardial ischemia identifies those who will have cardiac events, is more sensitive than the ECG, and has significant incremental value when added to baseline clinical variables and the ECG.

Absence of parasympathetic control of heart rate after human orthotopic cardiac transplantation.

BACKGROUND: Partial reinnervation of cardiac sympathetic nerves has been observed after heart transplantation; we hypothesized that parasympathetic control to the heart after transplantation may return as well. To test this hypothesis, we examined heart rate responses produced by two cardiovascular reflexes whose efferent limbs are subserved by vagal fibers to the heart: (1) trigeminal reflex (simulated diving reflex) and (2) arterial baroreflex with phenylephrine injection. METHODS AND RESULTS: An "early" group (n=31, <24 months after transplantation) and a "late group" (n=27, >45 months after transplantation) were studied and compared with a control group with intact cardiac innervation (n=32) and a renal transplant group with similar transplant immunosuppressive regimen (n=11). For trigeminal reflex testing, responses of the donor sinus node (DSN) (sinus node controlling heart rate) and recipient sinus node (RSN) in the innervated remnant right atrium in cardiac transplant patients were compared with heart rate responses in the control groups. For arterial baroreflex testing, baroreflex gains for the DSN and RSN in the cardiac transplant groups were compared with those of the control group. With engagement of the trigeminal reflex, the DSN rate of both transplant groups changed minimally (early, 1.2+/-1.2 bpm; late, 1.8+/-2.5 bpm) compared with the expected decrease in control subjects (-19.8+/-3.0 bpm) and renal transplant patients (-23.9+/-4.9 bpm) (P<.001 versus cardiac transplants). Changes in the RSN rate of both cardiac transplant groups (early, -13.0+/-4.0 bpm; late, -10.0+/-3.7 bpm) were similar to the control groups. Arterial baroreflex gains for the DSN were also depressed (early, 0.1+/-0.2 ms/mm Hg; late, 0.2+/-0.2 ms/mm Hg) compared with control (14.9+/-1.8 ms/mm Hg) and RSN (early, 9.9+/-1.3 ms/mm Hg; late, 10.9+/-1.3 ms/mm Hg; P<.001 versus DSN transplant). CONCLUSIONS: These data suggest that parasympathetic influences on donor heart rate are absent in the majority of patients up to 96 months after cardiac transplantation.

Decreased dominance in a limited access test but normal maternal behavior in micrencephalic rats.

Micrencephalic offspring produced by gestational treatment with the antimitotic compound/methylazoxymethanol acetate (MAM) are remarkable for substantial preservation of function concurrent with severe neural stunting. Altered behaviors in these micrencephalics, including light shyness and response perseveration, are similar to those produced by frontal cortex lesions. Consistent with this, the frontal cortex is one of several regions severely stunted by gestational MAM treatment. Because the frontal cortex has been implicated in rodent social behavior, maternal behavior in females and dominance in both sexes were assessed. Dominance was measured via water competition in 24-h water-deprived dyads (1 control and 1 MAM) matched for sex and body weight. Micrencephalic rats exhibited shorter drinking time than controls (males: 101 vs. 219 s, p < 0.001; females: 114 vs. 176 s, p < 0.03), indicating that micrencephalics were more submissive. For maternal behavior tests, micrencephalic and control females were bred to control males and pup retrieval was measured on postnatal days 3-13. Micrencephalic dams were unimpaired in any aspect of pup retrieval. Of 8 standard behavior measures used here and previously, access time in water competition tests produced the clearest differentiation between control and micrencephalic rats. These studies indicate that at least one aspect of social dominance in both sexes is severely reduced by MAM treatment while maternal behavior remains intact.

Evidence against reinnervation of cardiac vagal afferents after human orthotopic cardiac transplantation.

BACKGROUND: Orthotopic cardiac transplantation results in total cardiac denervation. Recent studies in humans suggest that reinnervation of cardiac sympathetic nerves (cardiac efferents) may occur after cardiac transplantation. We hypothesized that reinnervation of cardiac afferents may occur as well. To test this hypothesis, we investigated reflex responses produced by stimulation of ventricular chemosensory endings subserved by vagal afferents (cardiac depressor reflex). METHODS AND RESULTS: Two cardiac transplant groups were studied: an "early" group (n = 18, < 24 months after transplant) and a "late" group (n = 18, > 43 months after transplant); these groups were compared with a control group with intact innervation (n = 18). The reflex response of the recipient sinus node (RSN) in the remnant right atrium, which remains innervated after transplantation, was observed during selective right coronary artery (RCA) and left coronary artery (LCA) injection of the radiographic contrast agent meglumine diatrizoate, which is known to stimulate ventricular chemosensory endings. A decrease in the rate of the RSN was expected if reinnervation of chemosensory endings had occurred and the afferent limb of the cardiac depressor reflex was intact. With injection, the RSN rate of both transplant groups did not decrease but increased (early: LCA, 7.2 +/- 1.4 beats per minute; RCA, 6.3 +/- 1.3 beats per minute; late: LCA, 5.9 +/- 1.0 beats per minute; RCA, 6.0 +/- 0.9 beats per minute) compared with the expected decrease in control patients (LCA, -20.8 +/- 2.5 beats per minute; RCA, -18.0 +/- 4.0 beats per minute; P < .001 versus transplants). Decreases in mean arterial pressure in the transplant groups (early: LCA, -11.3 +/- 1.4 mm Hg; RCA, -10.0 +/- 1.6 mm Hg; late: LCA, -13.0 +/- 1.6 mm Hg; RCA, -9.1 +/- 1.5 mm Hg) were less than those observed in the control group (LCA, -19.8 +/- 2.2 mm Hg; RCA, -18.7 +/- 4.0 mm Hg; P < .05 versus transplants). CONCLUSIONS: The results suggest that reinnervation of ventricular chemosensory endings subserved by vagal afferents in cardiac transplant patients does not occur up to 74 months after transplantation.

Primary left ventricular mural endocarditis diagnosed by transesophageal echocardiography.

Primary left ventricular mural abscess was detected by transesophageal echocardiography and was confirmed at necropsy in a 44-year-old woman with Staphylococcus aureus bacteremia and cerebrovascular embolism. In two occasions, transthoracic echocardiography failed to show the mural abscess in this patient. Because of the aggressive nature of primary mural endocarditis, early use of transesophageal echocardiography is recommended in patients with Staphylococcal bacteremia and suspected endocarditis even in the absence of valvular abnormalities detectable by the transthoracic approach.

Odontogenic keratocysts: a study of 50 patients.

The odontogenic keratocyst (OKC) is a locally aggressive neoplasm with rates of recurrence reported as high as 60%. Correlation between histopathology and the likelihood of recurrence remains a subject of controversy. In this review of the authors' experience in treating 50 patients with OKC between 1977 and 1993, 58 specimens were studied to correlate the likelihood of recurrence with the presence of the following histologic features--parakeratosis, orthokeratosis, satellite cysts, epithelial rests, or epithelial proliferation. Orthokeratinized cysts were associated with a higher recurrence rate than in previously reported studies. Disruption of the epithelial lining in the resected specimen was found to be a primary determinant of recurrence.

Esophageal foreign body after smoking crack cocaine.

Injuries from cocaine abuse are often seen and have been reported more often with the introduction of crack cocaine. Burns of the upper aerodigestive tract have been reported but no reports of esophageal obstruction have been located. We report ingestion of a foreign body from smoking crack cocaine and our management. A review of other possible aspiration and ingestion injuries is included.

Modulation of the QT interval: effects of graded exercise and reflex cardiovascular stimulation.

During exercise, as heart rate (HR) increases, the QT interval of the electrocardiogram shortens. The mechanism(s) involved in this QT shortening has not been clearly defined. To distinguish the influence of increased circulating catecholamines from myocardial efferent stimulation, the relationship between HR and QT interval was investigated during exercise and cardiovascular reflex stimulation in cardiac transplant patients and normal control subjects. Because of cardiac denervation, increases in HR in these patients are solely due to circulating catecholamines and thus allow isolation of their effect on the QT interval. Twenty-one cardiac transplant patients were studied and compared with 16 normal control subjects. The QT-HR relationship was determined according to an exponential model during treadmill exercise in both groups [QT = 0.12 + 0.492e(-0.008.HR) and QT = 0.12 + 0.459e(-0.007.HR) in normal subjects and transplant patients, respectively] and was statistically similar between groups, suggesting similar QT interval shortening in both groups. During cold pressor and Valsalva maneuvers, HR increased significantly in normal subjects only, whereas QT interval changed minimally in both groups. These results suggest that during exercise the QT interval is influenced predominantly by increases in circulating catecholamines rather than by neurally mediated reflex autonomic changes.

Significance of MRI changes after surgery of the skull base.

Magnetic resonance (MR) imaging is commonly used in the followup of patients who have undergone surgical removal of tumors from the cranial base to assess the possibility of tumor recurrence, persistence, or surgical complications. Interpretations of this study must be cautious because postoperative enhanced signals are encountered frequently. Although technological improvements continue to enhance the usefulness of MR images for followup, problems remain in differentiating between fibrotic, reconstructive changes, and tumor recurrence. In this study, the hospital records and MR findings of 215 patients who had undergone skull base surgery were reviewed. The study was prompted by negative operative exploration in three patients in whom postoperative MR images strongly suggested tumor recurrence. One-year follow-up images were available in 174 patients. Of these, 94% showed signal enhancement on the 1-year follow-up study. Progressive changes were observed in 14% of patients. The correlation of preoperative MR findings and surgery, with regard to dural involvement, vascular involvement, cranial nerve infiltration, and extent of intracranial infiltration, was analyzed in 28 patients. Methods to facilitate the detection of tumor recurrence using MR images are reviewed.

Assessment of thallium scintigraphy and echocardiography during dobutamine infusion for the detection of coronary artery disease.

Dobutamine infusion was performed in 16 patients following cardiac catheterization, and non-invasive assessment was performed with thallium SPECT and echocardiography. Dobutamine thallium scintigraphy was abnormal in 93% of patients with significant coronary artery disease. In addition, individual epicardial vessel involvement was identified by a corresponding perfusion defect with 88% sensitivity and 93% specificity. Dobutamine echocardiography revealed segmental wall motion abnormalities in 62% of patients with significant coronary disease. However, in six patients baseline segmental wall motion abnormalities on echocardiography improved during dobutamine infusion. Dobutamine thallium SPECT is a safe and useful test for the detection and localization of coronary artery disease. Dobutamine echocardiography is less useful in screening for coronary disease, but may detect areas of abnormally functioning myocardium having retained viability.

Cardiopulmonary reflexes do not modulate exercise pressor reflexes during isometric exercise in humans.

Previous studies that measured reflex vasoconstrictor responses during isometric exercise have suggested that these responses were modulated by arterial and cardiopulmonary baroreflexes. The purpose of these experiments was to determine forearm vasoconstrictor responses to isometric handgrip alone and during two levels of cardiopulmonary baroreceptor unloading with lower body negative pressure (-5 and -10 mmHg LBNP). Handgrip combined with -5 mmHg LBNP produced vasoconstrictor responses that were significantly greater than the algebraic sum of the separate responses to handgrip and LBNP alone, thus confirming earlier studies. However, with -10 mmHg LBNP, the vasoconstrictor responses to LBNP plus handgrip were not different from the algebraic sum of the separate response to LBNP and handgrip alone. These results indicate that when the influence of cardiac baroreceptors was reduced to a greater degree (-10 mmHg LBNP) than in previous studies, no interaction was observed, whereas with less reduction (-5 mmHg LBNP) an apparent interaction was noted. These data, together with recent studies in which sympathetic nerve activity to the lower leg was measured during similar protocols, suggest nonlinearities in the relationship between sympathetic nerve activity and vasoconstrictor responses.

Doppler echocardiographic assessment of an impedance-based dual-chamber rate-responsive pacemaker.

Rate-responsive pacing allows patients with chronotropic incompetence to achieve more physiologic heart rate responses to exercise. One sensor currently being investigated uses impedance-derived measurements of changes in right ventricular stroke volume to alter the pacing rate. Correlation of pacemaker-derived measurements of stroke volume with an accepted method of stroke volume measurement has not been performed. The relative changes in impedance-derived stroke volume were compared in 10 patients with an impedance-based dual-chamber rate-responsive pacemaker (Precept DR, Cardiac Pacemakers, Inc.) with simultaneous Doppler echocardiographic measurements of right and left ventricular stroke volume. These comparisons were made during pacing at 2 heart rates (70 and 100 beats/min) and 3 AV intervals (150, 200 and 250 ms) while in a supine resting state, during lower body negative pressure to -30 mm Hg, and while performing 25% maximal handgrip. Pacemaker-derived stroke volume decreased by 7 to 11% and Doppler time-velocity integral measurements decreased by 14 to 19% in response to an increase in pacing rate (p = NS). There was also no significant difference by either technique in the mean stroke volume change when the atrioventricular interval was varied. Both techniques detected a decrease in stroke volume during lower body negative pressure, ranging from -7 to -20% by pacemaker, and -17 to -38% by Doppler. Overall, the pacemaker stroke volume measurements responded in an appropriate direction to each intervention, signaling the pacemaker's ability to detect directional change in stroke volume. The Precept DR may aid in the programming of parameters such as atrioventricular interval and heart rate by allowing for optimization of stroke volume in individual patients.

Echocardiographic profile of the transplanted human heart in clinically well recipients.

Thirty-four clinically well heart transplant recipients, aged 21 to 60 years, were selected for echocardiographic study at 12 +/- 2 months after transplantation. All had normal findings at stress thallium scintigraphy and at radionuclide left ventriculography, and no endomyocardial biopsy evidence of rejection was found within 36 hours of study. Multiple echocardiographic measurements were compared with those from two control groups. The first control group consisted of 15 normal subjects of similar ages as the donors, and the second group consisted of 15 normal subjects of similar ages as the recipients. Left ventricular mass (193 +/- 55 gm) was significantly increased in the transplant recipients compared with both control groups (p less than 0.001). Left ventricular volumes and ejection fractions of the transplanted heart, however, were normal. Right ventricular diastolic wall thickness (0.6 +/- 0.1 cm) and chamber area in both diastole (23.3 +/- 3 cm2) and systole (15.7 +/- 4 cm2) were significantly increased in the transplant patients (p less than 0.001), but fractional area change was similar to that of the normal group. Both left atrial area (26.9 +/- 4 cm2) and right atrial area (20.7 +/- 4 cm2) were significantly increased in the transplant recipients (p less than 0.001). One year after transplantation, clinically well recipients are characterized by increased left ventricular mass, but normal volumes and ejection fraction, increased right ventricular wall thickness and cavity size, but normal right ventricular systolic function, and markedly dilated atria.

Effects of exercise on left ventricular diastolic performance in trained athletes.

Dynamically trained athletes develop increased left ventricular (LV) wall mass. To determine whether this increased wall mass impaired characteristics of LV diastolic filling, serial Doppler echocardiograms were obtained from 10 trained athletes (mean age 21 years) at rest, during supine graded bicycle exercise and during recovery at heart rates of 80, 120 and 140 beats/min, respectively. Similar studies were obtained in 10 age-matched control subjects. Studies at rest showed significant increases in athletes in LV end-diastolic dimension and indexed LV wall mass. Differences in peak filling rates and in normalized peak lengthening rates between athletes and control subjects were seen at heart rates of 140 beats/min during exercise and recovery. Differences in Doppler-derived variables between athletes and control subjects were seen in total time-velocity integral, early peak filling velocity and E/A ratio. In athletes, time-velocity integral was increased during recovery at heart rates of 120 beats/min and 80 beats/min, early peak filling velocity was increased during exercise at 120 beats/min and during recovery at 120 beats/min and 80 beats/min, and E/A ratio was higher at all heart rates during both exercise and recovery. Although no significant differences were found in LV diastolic filling indexes at rest, a significant enhancement was found in these parameters in dynamically trained athletes during exercise, particularly at higher levels of dynamic exercise.