Temporal evolution of changes in left ventricular function induced by cold pressor stimulation. An assessment with radionuclide angiography and gold 195m

Transcutaneous electrical acupoint stimulation potentiates analgesic effect of morphine

Pain is the major complaint of patients who choose acupuncture treatment. Transcutaneous electrical acupoint stimulation (TEAS) provides a safe, standardized technique without needle insertion. TEAS can be tested with the cold-pressor test, a simple, reliable, and widely used model in humansfor the induction of tonic pain. In this controlled study, the effects of TEAS on cold-pressor-induced pain were evaluated in 20 healthy human subjects. Electrical stimulation electrodes were applied to He-Gu (LI 4) and Nui-Guan (P 6) acupoints. The effects of saline plus no TEAS, 15-minute TEAS alone, 0.05 mg/kg morphine alone, and 15-minute TEAS plus morphine were assessed. Pain score ratings were evaluated at four time points from 30 to 170 seconds during the cold-pressor test. The authors observed analgesic effects in both TEAS-alone and morphine-alone sessions, and pain score rating reductions were statistically significant compared to unstimulated control (both p < 0.01). The degree of TEAS analgesia combined with 0.05 mg/kg morphine was significantly higher than TEAS alone (p < 0.01). The results support the efficacy of TEAS analgesia and suggest that combination of TEAS with low-dose morphine can achieve better pain control in a variety of clinical settings.

Dose-related effects of oral acetaminophen on cold-induced pain: a double-blind, randomized, placebo-controlled trial

The cold-pressor test is a widely used pain-induction model in humans. This method has been shown to be a sensitive measure for detecting opioid analgesia. However, nonsteroidal anti-inflammatory drugs have not produced consistent analgesic effects with use of this model. The analgesic effect of acetaminophen (INN, paracetamol) on cold pressor-induced pain has not been reported by other investigators. In this study, a double-blind, randomized, placebo-controlled design was used to evaluate the dose-related effects of oral acetaminophen on cold pressor-induced pain in 18 normal healthy human subjects. We observed dose-related analgesic activity of oral acetaminophen using the cold pressor-induced pain model in these subjects. There were statistically significant main effects of both dose and time (pain and bothersomeness ratings decreased with increasing drug dose and increased over time). In pairwise comparisons only the contrast between the highest dose of acetaminophen (1000 mg) and placebo reached statistical significance. Results from our study suggest that the cold-pressor method may have clinical value in evaluating nonopioid analgesic agents.

Analysis of cardiac arrhythmias during dobutamine pharmacologic stress testing in nuclear cardiology as related to the presence or absence of baseline arrhythmias

BACKGROUND

Intravenous dobutamine is an acceptable pharmacologic stress agent for evaluation of myocardial ischemia, but it has the undesirable side effect of precipitating cardiac arrhythmias. All patients are susceptible to the arrhythmogenic potential of dobutamine. However, the presence of a baseline arrhythmia creates additional concern about proceeding with a pharmacologic dobutamine stress test. The purpose of this study was to evaluate cardiac arrhythmias during dobutamine stress as they relate to the presence or absence of baseline arrhythmias in patients undergoing radionuclide myocardial perfusion imaging.

METHODS AND RESULTS

Data from 486 consecutive dobutamine stress tests in nuclear cardiology were reviewed retrospectively. Baseline and stress electrocardiographic monitoring and 12-lead electrocardiograms were used for classification of arrhythmias. For patients without baseline arrhythmias, the estimated probability of having nonsustained ventricular tachycardia with dobutamine stress was 4.0% (16 of 403), as compared with 15.7% (13 of 83) for patients with baseline arrhythmias (p < 0.001). Three of the 403 patients (0.7%) and 2 of the 83 patients (2.4%) had their study terminated because of ventricular tachycardia (p > 0.05).

CONCLUSIONS

The probability of having nonsustained ventricular tachycardia with dobutamine stress testing was significantly greater in patients who had baseline arrhythmias than in those who had no arrhythmias at baseline. Although termination of the study because of ventricular tachycardia was not statistically significant between these two groups, patients with baseline cardiac arrhythmias should be considered at higher risk for the development of nonsustained ventricular tachycardia during dobutamine stress testing than patients who have no baseline arrhythmia.

Cardiac involvement in scleroderma

In summary, cardiac involvement in systemic sclerosis can be manifested as myocardial disease, pericardial disease, conduction system disease, or arrhythmias. Clinical cardiac involvement is a poor prognostic factor. Asymptomatic cardiac abnormalities are frequent, and all cardiac abnormalities are seen more often in diffuse scleroderma. Unlike other organs, the role of vascular involvement is unclear. At present, treatment of cardiac scleroderma is essentially symptomatic and empiric. The role of vasodilation and immunosuppression needs further exploration.

Reproducibility of the cold pressor test: studies in normal subjects

The reproducibility of the cold pressor test was studied in healthy subjects. A non-invasive method was utilized for estimating beat-to-beat arterial blood pressure (BP) and heart rate (HR). The study population of 17 healthy volunteers consisted of two groups. In the first group (Group 1, n = 11), a 1-min test was performed three times during the same day. In the second group (Group 2, n = 6), a 2-min test was repeated at the same time of the day on three consecutive days. In both groups, the test response was defined as the 46- to 60-s mean, minus the prestimulus 15 s baseline mean. In Group 1, a fair test-retest reliability was observed for the systolic BP response (intraclass correlation coefficient R = 0.57). Large intraindividual HR and diastolic BP variabilities were found. The intraindividual testretest difference in Group 1 ranged from -8 to 11 beats/min (SD = 4.3, R = 0.49) for the HR, from -16 to 13 mmHg (SD = 6.3) for systolic BP, and form -21 to 20 mmHg (SD = 9.7, R = 0.23) for diastolic BP. Even larger variability was observed when the test was repeated on different days (Group 2). Thus, the maxim that the response pattern to the cold pressor test is fairly constant for each individual may not be true. It does not seem to be advisable to use the results from one solitary cold pressor test. The use of replicated measurements and large sample sizes in comparative studies to compensate for the low to moderate reliability of the cold pressor test is recommended.

Exercise-related changes in aortic flow measured with spiral echo-planar MR velocity mapping

Spiral echo-planar magnetic resonance (MR) velocity mapping was used to measure exercise-related changes in flow in the descending thoracic aorta in 10 healthy volunteers. Flow was measured at rest and immediately after dynamic exercise, with a 0.5-T imager with a surface receiving coil and electrocardiographic triggering. Supine exercise was performed with a home-built pedaling apparatus. Spiral velocity mapping was performed in a transverse plane through the descending thoracic aorta with the subject at rest. The subject was then asked to perform maximum exercise, stop, and hold his breath during a four-heartbeat acquisition time. Eight cine frames with a temporal resolution of 50 msec were acquired through systole. Each image was acquired in 40 msec during spiral acquisition of k-space data, starting at the center, 6 msec after the excitation pulse. Reproducibility of the technique was established by repeating the flow measurement in four consecutive heartbeats. At rest, the heart rate (mean +/- standard deviation), mean aortic flow, peak aortic flow, and time to peak flow were 68 beats per minute +/- 6, 41 milliliters per beat +/- 8, 107 mL/sec +/- 20, and 175 msec +/- 25, respectively. After exercise, the heart rate and mean and peak aortic flow were significantly increased (P < .001), measuring 101 beats per minute +/- 12, 57 milliliters per beat +/- 11, and 158 mL/sec +/- 29, respectively, while the time to peak flow (115 msec +/- 32) was significantly reduced (P < .001). The four sets of values obtained for the first four consecutive heartbeats measured at rest were similar, as were those obtained for the first four heartbeats after exercise.

Dobutamine thallium myocardial perfusion tomography

Dobutamine has favorable properties for the pharmacologic manipulation of myocardial oxygen demand in the provocation of ischemia during the investigation of coronary artery disease. The value of dobutamine infusion for thallium myocardial perfusion tomography was assessed in 50 patients with exertional chest pain undergoing coronary arteriography. Dobutamine was infused in 5-min stages at incremental rates from 5 to 20 micrograms/kg per min or until limited by symptoms. The myocardium was divided into nine segments for analysis of perfusion. Thirty-nine of 40 patients with coronary artery disease had a reversible perfusion defect demonstrated by dobutamine thallium tomography (sensitivity 97%) and 8 of 10 patients with normal coronary arteries had normal myocardial perfusion (specificity 80%). These values were significantly better than the sensitivity and specificity of exercise electrocardiography (78% and 44%, respectively; p less than 0.01). There was a significant relation between the mean number of segments with abnormal perfusion and the number of diseased coronary vessels (0.6, 2.6, 4.4 and 6 segments in zero-, one-, two- and three-vessel disease, respectively; p less than 0.001). There was also a significant relation between the maximal tolerated dose of dobutamine and the treadmill exercise time (r = 0.56, p less than 0.001), but a wide range of exercise times was achieved in the 15- and 20-micrograms/kg per min groups, principally because of exercise limitation by noncardiac symptoms. Dobutamine infusion was well tolerated in all patients, including six with asthma. There were no significant arrhythmias or limiting symptoms other than chest pain.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of respiratory variations on right ventricular function

Respiratory effort during inspiration, expiration, and the Valsalva manoeuvre changes right ventricular preload and afterload. On inspiration these changes should improve systolic emptying of a larger end diastolic volume and so increase the ejection fraction, whereas on expiration the reverse should be true. The resting right ventricular ejection fraction was measured by first pass radionuclide angiography with gold-195m (half life 30.5 s) in 17 individuals at maximal inspiration and expiration and in eight at rest and during the strain phase (phase 2) of the Valsalva manoeuvre. The right ventricular ejection fraction was significantly lower during expiration than during inspiration. There were, however, no significant differences in bolus duration or right ventricular transit time. The Valsalva manoeuvre, in contrast, significantly increased the ejection fraction and also significantly prolonged both the bolus duration and right ventricular transit time. The conformation of the bolus curves during the Valsalva manoeuvre suggested the development of tricuspid regurgitation. These data suggest that relative influences of venous return, pulmonary arterial pressure, pulmonary vascular resistance, and possible functional tricuspid regurgitation vary during inspiration, expiration, and the Valsalva manoeuvre and can affect the right ventricular ejection fraction. Changes in right ventricular function on exercise assessed by first pass radionuclide angiography must be interpreted with caution because maximal respiratory effort may alter the right ventricular ejection fraction independently of ischaemia or other non-ischaemic factors.

Evaluation of coronary artery disease in the patient unable to exercise: alternatives to exercise stress testing

Exercise stress testing is a well-established method for the diagnostic, prognostic, and functional assessment of patients with known or suspected CAD. A variety of alternative tests have been described in patients unable to perform leg exercise. Atrial pacing and dipyridamole imaging have been evaluated most extensively, and results compare favorably with those of exercise testing for diagnosing the presence of CAD. Both tests may be used to assess prognosis after myocardial infarction, and dipyridamole imaging may be useful in patients undergoing preoperative evaluation. The use of the cold pressor test and isometric handgrip exercise have also been described. However, the value of both tests is limited by a relatively low sensitivity for detecting the presence of CAD. Other testing modalities--arm ergometry, intravenous infusion of beta-adrenergic agonists, and transthoracic pacing--show promise but require further assessment to confirm their value.

Nonischemic changes in right ventricular function on exercise. Do normal volunteers differ from patients with normal coronary arteries?

Factors other than ischemia may alter right ventricular function both at rest and on exercise. Normal volunteers differ from cardiac patients with normal coronary arteries with regard to their left ventricular response to exercise. This study examined changes in right ventricular function on exercise in 21 normal volunteers and 13 patients with normal coronary arteries, using first-pass radionuclide angiography. There were large ranges of right ventricular ejection fraction in the two groups, both at rest and on exercise. Resting right ventricular ejection fraction was 40.2 +/- 10.6% (mean +/- SD) in the volunteers and 38.6 +/- 9.7% in the patients, p = not significant, and on exercise rose significantly in both groups to 46.1 +/- 9.9% and 45.8 +/- 9.7%, respectively. The difference between the groups was not significant. In both groups some subjects with high resting values showed large decreases in ejection fraction on exercise, and there were significant negative correlations between resting ejection fraction and the change on exercise, r = -0.59 (p less than 0.01) in volunteers, and r = -0.66 (p less than 0.05) in patients. Older volunteers tended to have lower rest and exercise ejection fractions, but there was no difference between normotensive and hypertensive patients in their rest or exercise values. In conclusion, changes in right ventricular function on exercise are similar in normal volunteers and in patients with normal coronary arteries. Some subjects show decreases in right ventricular ejection fraction on exercise which do not appear to be related to ischemia.

How useful are the cold pressor test and sustained isometric handgrip exercise with radionuclide ventriculography in the evaluation of patients with coronary artery disease?

The feasibility of using the cold pressor test and the sustained isometric handgrip test as alternatives to dynamic exercise for stressing the heart was investigated. Serial changes in heart rate, blood pressure, and left ventricular performance induced by these tests were studied by radionuclide ventriculography in patients with coronary artery disease and in normal volunteers. Both tests significantly increased heart rate and blood pressure. The reproducibility of serial evaluation of ejection fraction response to cold pressor and isometric handgrip stresses was satisfactory but the sensitivity for detecting coronary artery disease was not. Both stress tests are valuable interventions for the serial evaluation of left ventricular function by radionuclide ventriculography, but they should not be used to detect coronary artery disease.

A new method of imaging the right ventricle using peripheral vein infusion of xenon 127

We report the development of a new method for obtaining right ventriculograms using the peripheral intravenous infusion of a new tracer, 127Xe dissolved in saline. This tracer has a half life of 36 days, emits 172 keV and 203 keV photons, and is completely cleared by the lungs during pulmonary transit. The right ventricle can therefore be imaged free from interfering activity in the systemic circulation. The technique was used in 11 normal subjects and the results compared with those obtained using first pass and gated equilibrium blood pool angiography with 99mTc. Excellent images of the right ventricle were obtained and the tricuspid and pulmonary valve planes could be easily identified. This imaging technique has significant advantages over existing methods for the noninvasive assessment of right ventricular function.

Comparison of ultrashort-lived iridium-191m with technetium-99m for first pass radionuclide angiocardiographic evaluation of right and left ventricular function in adults

Ultrashort-lived iridium-191m (Ir-191m, physical half-life = 5.0 seconds) has been used in angiocardiography, primarily in pediatric patients. A theoretical obstacle to more widespread use of Ir-191m is the belief that its physical half-life is too short to permit evaluation of left ventricular function in adult patients. To evaluate its usefulness in adults, first pass ejection fractions of the left and right ventricles determined with use of Ir-191m and technetium-99m (Tc-99m) were compared in 33 adult patients. An osmium-191m----iridium-191m (Os-191----Ir-191m) generator was employed to deliver doses of 150 to 250 mCi (5.5 to 9.2 GBq) of Ir-191m for intravenous injection. The whole body radiation absorbed dose with Ir-191m was 15 to 25 mrad. High quality angiocardiograms were obtained with both Tc-99m and Ir-191m. Total counts per image for the right ventricle were 51,000 +/- 8,000 (mean +/- SD) for Ir-191m and 30,000 +/- 8,000 for Tc-99m. The left ventricular counts were comparable for both radiotracers (25,000 +/- 7,000 for Ir-191m and 25,000 +/- 8,000 for Tc-99m). Right ventricular ejection fractions were similar: 44 +/- 8% for Ir-191m and 47 +/- 9% for Tc-99m. The correlation coefficient was 0.93 with a standard deviation of the regression of 3.1% ejection fraction units. The left ventricular ejection fractions were also similar: 45 +/- 14% for Ir-191m and 46 +/- 13% for Tc-99m. The left ventricular ejection fraction correlation coefficient was 0.96 with a standard deviation of the regression of 3.7%.(ABSTRACT TRUNCATED AT 250 WORDS)

Left ventricular function during isometric hand grip and cold stress in normal subjects

Both isometric exercise and cold stress have been suggested as alternatives to dynamic exercise for the detection of obstructive coronary artery disease. A non-imaging nuclear probe was used to measure left ventricular ejection fraction and relative left ventricular volumes continuously during both of these stress tests in 24 normal subjects. There was a significant fall in left ventricular ejection fraction within 15 seconds of subjects starting a two minute isometric hand grip test at 50% maximal voluntary contraction, with a mean (SE) maximal fall of 10% (1.8) after 90 seconds. During two minutes immersion of the hand and wrist in iced water left ventricular ejection fraction fell significantly within 30 seconds with a mean maximal fall of 7% (1.7) after one minute. Nine subjects underwent repeat tests under identical conditions approximately two weeks later. The standard error of the change in ejection fraction on two occasions was 5.4% at rest, 7.0% at the peak of isometric exercise, and 4.8% at peak cold stress. These results indicate that the reproducibility of both of these stress tests is acceptable when they are performed under carefully controlled conditions. The resulting changes in ejection fraction are transient, however, and moreover depend upon the choice of stress protocol. The discrepancies between published reports of such studies in coronary artery disease may be mainly due to methodological differences, and neither test is likely to be of sufficient discriminative ability to distinguish between individuals with obstructive coronary artery disease and normal subjects.

The cold pressor test during radionuclide ventriculography: a feasibility study in cancer patients

To monitor the use of cardiotoxic drugs, adequate assessment of myocardial function is required. Although serial radionuclide left ventricular ejection fraction (EF) studies allow a simple and rapid assessment of the myocardial function without risk or discomfort to the patient, they appear not to be sensitive enough. Determination of the EF during cold application may be more sensitive. In this study we tested the feasibility of the cold pressor test (CPT) in relation to EF determination in 23 cancer patients. Only minor side effects were recorded. The response of heart rate to cold was similar to the response reported in healthy volunteers and patients with coronary artery disease. In selected cases EF determination during CPT appeared to be more sensitive than EF at rest. EFCPT may be an attractive alternative for EFexercise in cancer patients who cannot perform enough exercise to stress cardiac function adequately, but for a more definite conclusion a prospective comparative study is required.

Effects of projection and background correction method upon calculation of right ventricular ejection fraction using first-pass radionuclide angiography

There is no consensus as to the best projection or correction method for first-pass radionuclide studies of the right ventricle. We assessed the effects of two commonly used projections, 30 degrees right anterior oblique and anterior-posterior, on the calculation of right ventricular ejection fraction. In addition two background correction methods, planar background correction to account for scatter, and right atrial correction to account for right atrio-ventricular overlap were assessed. Two first-pass radionuclide angiograms were performed in 19 subjects, one in each projection, using gold-195m (half-life 30.5 seconds), and each study was analysed using the two methods of correction. Right ventricular ejection fraction was highest using the right anterior oblique projection with right atrial correction 35.6 +/- 12.5% (mean +/- SD), and lowest when using the anterior posterior projection with planar background correction 26.2 +/- 11% (p less than 0.001). The study design allowed assessment of the effects of correction method and projection independently. Correction method appeared to have relatively little effect on right ventricular ejection fraction. Using right atrial correction correlation coefficient (r) between projections was 0.92, and for planar background correction r = 0.76, both p less than 0.001. However, right ventricular ejection fraction was far more dependent upon projection. When the anterior-posterior projection was used calculated right ventricular ejection fraction was much more dependent on correction method (r = 0.65, p = not significant), than using the right anterior oblique projection (r = 0.85, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of an opiate on cold-induced pain and the CNS in healthy volunteers

The analgesic activity of an opiate was studied in 12 healthy volunteers using a cold-induced pain (CP) model. Effects on the central nervous system (CNS) were also measured. According to a double-blind, randomised, balanced, cross-over design with an interval of 7 days between occasions, subjects received single oral doses of 2, 4 and 8 mg dipipanone (D2, D4, D8) and a placebo. The CP test and a battery of measurements of CNS function were performed 3 times on each study day, once before and again 1.5 h and 3.0 h after treatment. Mean pain cores on a computerised visual analogue scale were significantly higher after placebo than those after 4 mg (P less than 0.05) and 8 mg (P less than 0.01) dipipanone and a dose-response relationship was evident. The opiate did not affect baseline blood pressure before the CP test but the hypertensive response to the painful cold stimulus was diminished 3 h after D8. Scores on scales for subjective assessment of alertness were significantly reduced 3 h after the 8 mg dose and pupil diameters were significantly smaller after all 3 doses of dipipanone. Body sway and visual near points were not significantly altered by the opiate. It is concluded that the CP test is a sensitive model for measurement of opiate-induced analgesia in healthy volunteers. Pupillometry and visual analogue scales are useful for the assessment of central effects of opiates.

Regional coronary hemodynamic responses during the cold pressor test: lack of effect of nitroglycerin

The effects of large coronary vessel dilation on responses to immersion of a hand and forearm in ice water for 1 minute (that is, the cold pressor test) were calculated for 17 patients. Regional coronary blood flow and aortic and left ventricular pressures were continuously measured before and during two cold pressor tests, each performed before and after administration of sublingual (0.4 mg) or low dose intracoronary (0.01 mg) nitroglycerin. During the initial cold pressor test, heart rate and coronary pressures increased in all patients; total and regional coronary resistance usually increased in patients with severe coronary artery disease and usually decreased in patients with a normal coronary angiogram. Sublingual nitroglycerin induced important systemic effects, but intracoronary nitroglycerin did not; both induced dilation of coronary arteries viewed angiographically. Regardless of the route of nitroglycerin administration, coronary hemodynamic responses were directionally similar during the repeat cold pressor test compared with the initial one. These data support the concept that changes in tone of the large coronary arteries are not important in producing the cardiac responses observed during the cold pressor test.