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PubMed2001

Pulse pressure and risk of cardiovascular events in the systolic hypertension in the elderly program.

Pulse pressure has been related to higher risk of cardiovascular events in older persons. Isolated systolic hypertension is common among the elderly and is accompanied by elevated pulse pressure. Treatment of isolated systolic hypertension may further increase pulse pressure if diastolic pressure is lowered to a greater extent than systolic pressure. Little is known regarding pulse pressure as a predictor of cardiovascular outcomes in elderly persons with isolated systolic hypertension, and the influence of treatment on the pulse pressure effect. We assessed the relation between pulse pressure, measured throughout the follow-up period, and the incidence of coronary heart disease (CHD), heart failure (HF), and stroke in 4,632 participants in the Systolic Hypertension in the Elderly Program, a 5-year randomized, placebo-controlled clinical trial of treatment of isolated systolic hypertension in older adults. In the treatment group, a 10-mm Hg increase in pulse pressure was associated with a statistically significant 32% increase in risk of HF and a 24% increase in risk of stroke after controlling for systolic blood pressure and other known risk factors, as well as with a 23% increase in risk of HF and a 19% increase in risk of stroke after controlling for diastolic blood pressure and other risk factors. Pulse pressure was not significantly associated with HF or stroke in the placebo group, nor with incidence of CHD in either the placebo or treatment group. These results suggest that pulse pressure is a useful marker of risk for HF and stroke among older adults being treated for isolated systolic hypertension.

Aged↗
PubMed2002

Correlates of pulse pressure reduction during antihypertensive treatment (losartan or atenolol) in hypertensive patients with electrocardiographic left ventricular hypertrophy (the LIFE study).

In hypertensive patients, pulse pressure has been related to hypertension-induced target organ damage and risk of cardiovascular events. However, correlates of pulse pressure reduction during antihypertensive treatment have been less extensively investigated. We related pulse pressure changes to clinical and echocardiographic findings before and after 2 years of antihypertensive treatment in 767 patients aged 55 to 80 years (mean 66) in the Losartan Intervention For End point reduction in hypertension study. Over 2 years, blood pressure and pulse pressure were reduced from 173/98 to 147/84 mm Hg and from 75 to 63 mm Hg, respectively, both p <0.001. In linear multivariate analysis controlling for initial pulse pressure, 2-year reduction in pulse pressure correlated negatively with age and concomitant diabetes mellitus, and positively with body height and 2-year reduction in mean blood pressure (multiple R(2) = 0.42, p <0.01). When dividing the study population into 2 groups using a prognostically validated partition for pulse pressure, patients with pulse pressure > or =63 mm Hg after 2 years of antihypertensive treatment (n = 349) were older and shorter, included more women and patients with isolated systolic hypertension, diabetes mellitus, albuminuria, and echocardiographic left ventricular hypertrophy at baseline, and also had a smaller decrease in mean blood pressure and the urinary albumin/creatinine ratio over 2 years (all p <0.05). Thus, in hypertensive patients with electrocardiographic left ventricular hypertrophy, older age, less reduction in mean blood pressure, concomitant diabetes mellitus, and shorter stature are associated with attenuated pulse pressure reduction during antihypertensive treatment.

Aged↗
PubMed2002

Usefulness of pulse deficit to predict in-hospital complications and mortality in patients with acute type A aortic dissection.

Vascular compromise seen with pulse deficits is common in patients with type A dissection. However, patient characteristics and in-hospital outcomes associated with pulse deficits have not been evaluated. Accordingly, we studied 513 patients (mean age 62 +/- 14 years, 65% men) with acute type A aortic dissection enrolled in the International Registry of Acute Aortic Dissection. Pulse deficits, defined as decreased or absent carotid or peripheral pulses as noted by clinicians and later confirmed by diagnostic imaging, at surgery or at autopsy were noted in 154 patients (30%). Age <70 years, male gender, neurologic deficit(s), altered mental status, and hypotension, shock, or tamponade on admission were all significantly higher in patients with than without pulse deficits. The etiology of aortic dissection, clinical symptoms, and imaging findings were similar in the 2 groups. In-hospital complications (hypotension, coma, renal failure, and limb ischemia) and mortality (41% vs 25%, p = 0.0002) were significantly higher in patients with pulse deficit. Cox proportional-hazards regression analysis identified pulse deficit as an independent predictor of 5-day in-hospital mortality (risk ratio 2.73, 95% confidence interval 1.7 to 4.4; p <0.0001). Further, overall mortality rates increased with an increasing number of pulse deficits (p for trend <0.0001). Pulse deficits are common findings in patients with type A aortic dissection and identify those at high risk of in-hospital adverse events. This simple clinical sign should direct physicians to consider a diagnosis of aortic dissection in patients with acute chest pain, and should help identify a subgroup of patients who would benefit from more aggressive strategies.

Aged↗
PubMed1998

Competence of health professionals to check the carotid pulse.

Our objective was to establish the proportion of Emergency Room and Intensive Care doctors and nurses able to locate the carotid pulse in less than 5 s, and identify the variables that influence this ability. The method followed was locating the carotid pulse in a healthy male adult volunteer with normal blood pressure in two situations (stretcher or floor) and with the neck in either a neutral or in an extended position. We recorded the gender, age, and previous training in cardiopulmonary resuscitation (CPR) of each participant and the time spent in detecting the pulse in each of the four possible positions. A model of logistic regression was constructed to determine if the patient's position had any influence on the proportion of health workers capable of finding the pulse within 5 s. The average age of the 72 subjects studied was 33.4 years (SD = 6.6); 80% of the participants had CPR training. Thirty-one participants (43.1%; CI 95%, 31.4-55.3%) required more than 5 s to detect the pulse, although only three (4.2%; CI 95%, 0.9-11.7%) required more than 10 s. The variable 'no CPR training' was associated with the inability to detect the pulse within 5 s. The detection of the pulse was easier with an extended neck. A significant proportion of nurses and doctors were slow to locate the carotid pulse on a healthy, young volunteer with normal blood pressure. No relation was found between gender or age of the participants. More attention should be given to carotid pulse detection in CPR training.

Adult↗
PubMed1999

Positive association between resting pulse and cancer incidence in current and former smokers.

PURPOSE: To evaluate the association between resting pulse and cancer incidence in older persons. METHODS: A cohort of 2819 persons, aged 65 to 102 years at baseline, was followed for the development of cancer from 1982 through 1993 by linkage to a statewide cancer registry; 494 incident cases were identified. Resting radial pulse (beats per minute) was measured during an in-person interview at baseline, and sex-specific quintile cutpoints were used in the analysis. RESULTS: After adjustment for age, body mass, smoking, and physical activity, there was a positive association between pulse and cancer incidence in men: compared to men with a pulse of < 63, men with a pulse of 63-68 (relative risk (RR); 95% confidence interval (CI): RR = 1.68; CI = 1.06-2.66), 69-74 (RR = 1.54; CI = 0.95-2.49), 75-82 (RR = 1.62; CI = 1.03-2.55), and > 82 (RR = 1.63; CI = 1.03-2.65) were at elevated risk for any cancer. This association remained unchanged after further adjustment for cardiovascular comorbidity, diabetes, alcohol use, high level of depressive symptoms, and low self-perceived health status. Exclusion of cases diagnosed in the first two years of follow-up did not alter the association. There was no overall association between pulse and cancer incidence in women. Analyses stratified by smoking status showed that the pulse and cancer association was strongest in ever smokers for both men and women. In subsite analysis for men, pulse was mainly associated with smoking-related tumors as a group and colorectal and prostate cancer. CONCLUSIONS: These data suggest that resting pulse is associated with cancer incidence, mainly among ever smokers.

Aged↗
PubMed1986

Physiology of the peaked finger pulse in normal and cold-sensitive subjects.

A unique peaked digital pulse contour (DPC) is frequently observed in patients with cold sensitivity, but the pathophysiology of this pulse remains obscure. To investigate the responses of the DPC to cold exposure, finger blood pressure (FBP), finger blood flow (FBF), and finger skin temperature (FST) were measured in fingers of both hands of 13 normal subjects and in 16 patients with cold sensitivity. The ratio, FBP/FBF, was used to estimate small vessel resistance (SVR). One hand was immersed sequentially in water at 40 degrees, 30 degrees, 20 degrees, and 10 degrees C, while the other hand remained in room air. DPCs were classified as normal (N), intermediate (I), intermediate-peaked (IP), peaked (P), obstructive (O), and spastic obstructive (SO). At room temperature, fingers with I, IP, O, and SO pulses had increased SVRs and decreased FSTs, and those with O and SO had decreased FBP. On cold exposure IP pulses appeared in both hands of both normal and cold-sensitive subjects, but P pulses developed only on the cooled side. IP and P pulses were associated with an increase in SVR. We concluded that IP pulses are related to reflex sympathetic arteriolar vasoconstriction, that P pulses imply vasoconstriction produced directly by cold exposure, and that O, SO, or absent pulses are indicative of digital arterial vasospasm.

Adolescent↗
PubMed2000

Fetal haemodynamic changes in fetuses during fetal development evaluated by arterial pressure pulse and blood flow velocity waveforms.

OBJECTIVE: To study the relation between diameter pulse (pressure pulse) and flow velocity waveforms in the fetal descending aorta in fetuses with intrauterine growth retardation and acceleration. DESIGN: Blood flow through a tubular system can be expressed by the ratio of blood pressure to vascular resistance. Doppler ultrasound and a phase locked loop echo tracking system coupled to a B-mode ultrasonic imager (central frequency 3.5 MHz) were used to assess downstream resistance and change in blood pressure, respectively. SETTING: Tertiary referral unit in a teaching hospital PARTICIPANTS: Serial study between 21 and 40 weeks of 22 women with normally grown fetuses at intervals of four weeks; 25 women with small for gestational age fetuses with uteroplacental insufficiency (high umbilical artery pulsatility index); and six women with large for gestational age fetuses. MAIN OUTCOME MEASURES: We measured the maximum systolic and minimum diastolic diameter of the fetal descending aorta (the pulse amplitude) and then calculated the pulsatile waveform time integral above the least diastolic diameter (pulsatile area) and total waveform time integral (perfusion area). RESULTS: Normal fetal growth was associated with an increase in systolic and diastolic diameters in the fetal descending aorta with advancing gestational age. Pulse amplitude, pulsatile and perfusion areas increased with gestational age. The increased pulse amplitude and increased pulsatile area in association with a decrease of the pulsatility index in the descending aorta during the second trimester suggested that pulse pressure and stroke volume were increased. In the group with intrauterine growth retardation, systolic and diastolic diameters of the descending aorta and perfusion area were within the normal range. Moreover, there was an increase in the diastolic diameter per unit fetal weight and a decrease in the pulsatile area. In the large for gestational age fetuses, there was an increase in the pulse amplitude and pulsatile area. CONCLUSION: These findings suggest that in growth restricted fetuses there is an increase in diastolic pressure and a reduction in stroke volume, while in large for gestational age fetuses there is an increase in the pulse pressure and stroke volume. It is possible that measurement of pressure pulse waveform in relation to Doppler velocity waveform may be used to infer changes of blood flow.

Blood Flow Velocity↗
PubMed1999

Contribution of stroke volume to the change in pulse pressure pattern with age.

This study investigated the effect of age on pulse pressure and its underlying mechanisms in unmedicated hypertensive men with the same level of mean arterial pressure. We included 77 men 17 to 76 years old with daytime mean arterial pressure between 95 and 114 mm Hg. In the supine position, pulse pressure showed a significant widening in young (<30 years) and older (>/=60 years) patients. Pulse pressure decreased in parallel with stroke index from age >30 to 40 to 49 years. Upright posture, however, eliminated this difference through a larger orthostatic fall in stroke index and pulse pressure in the youngest patients. After age 50 years, pulse pressure exhibited a progressive widening despite the further age-related decrease in stroke index. Supine, upright, and 24-hour pulse pressure fitted a curvilinear correlation with age (r=0.55, 0.56, and 0.68, respectively, P<0.001), with a transition at age 50 years. Before age 50 years, 24-hour pulse pressure correlated positively with stroke volume (r=0.5, P<0.001) and negatively with arterial compliance (SV/PP ratio, r=-0.37, P<0.01). In contrast, in men >/=50 years old, 24-hour pulse pressure correlated negatively with the SV/PP ratio (r=-0.5; P<0.01), without significant influence of stroke volume. Thus, in hypertensive men, the age-related change in stroke volume significantly accounted for the change in clinic and ambulatory pulse pressure during young adulthood, but its contribution decreased after the fifth decade.

Adult↗
PubMed2002

Association between pulse pressure and C-reactive protein among apparently healthy US adults.

Elevated pulse pressure has been associated with an increased risk of cardiovascular disease, which is increasingly being seen as an inflammatory disease. Thus, the mechanism underlying the link between elevated pulse pressure and cardiovascular disease risk may be inflammation. However, investigators have not examined the relationship between pulse pressure and C-reactive protein, an inflammation marker that has been closely linked to cardiovascular risk. We examined the cross-sectional relationship between pulse pressure and C-reactive protein among 9867 healthy persons 17 years of age or older who participated in the Third National Health and Nutrition Examination Survey. The association between pulse pressure and the odds of having an elevated C-reactive protein level (> or = 0.66 mg/dL) was assessed by logistic regression. In a model that adjusted for systolic blood pressure, demographic factors, cholesterol, measures of obesity, smoking, alcohol consumption, physical activity, and antihypertensive medication use, a 10 mm Hg increase in pulse pressure was associated with a 15% increase in the odds of having an elevated C-reactive protein level (odds ratio, 1.15; 95% confidence interval, 1.01 to 1.31; P=0.04). When the same model was re-run adjusting for diastolic blood pressure instead of systolic blood pressure, a 10 mm Hg rise in pulse pressure was associated with a significant 12% increase in the odds of having an elevated C-reactive protein level. Systolic and diastolic blood pressure were unrelated to C-reactive protein once pulse pressure had been accounted for. Our results suggest that increases in pulse pressure are associated with elevated C-reactive protein levels among apparently healthy US adults, independent of systolic and diastolic blood pressure.

Adult↗
PubMed1993

Spectral analysis of radial pulse in patients with acute, uncomplicated myocardial infarction.

The aim of this study was to examine the frequency spectrum of arterial pulses in 17 patients with acute, uncomplicated myocardial infarction. Recordings of right radial pulses were taken from these patients immediately after their arrival at the emergency room. This information was considered as baseline data and was monitored at the same time each day for up to 7 days. These serial recordings of radial pulses were then analyzed together with recordings from 3 control groups of patients not suffering from myocardial infarction. These included subjects who underwent coronary arteriography (n = 24), coronary angioplasty (n = 18), and mitral valvuloplasty (n = 13). The method of analysis involved a discrete Fourier transformation of radial pulses recorded from an external pulsation transducer to obtain "power spectra" for pulse waves. There was no significant change in the power spectrum for each of the 3 control groups although significant clinical and hemodynamic improvement was observed in the coronary angioplasty and mitral valvuloplasty patients. In sharp contrast, the intensity of the frequency moduli C2 and C3 in the target group fell on arrival at the emergency room and then gradually increased while the average pulse energy (frequency modulus C0) decreased simultaneously with stable recovery from the acute myocardial infarction. In order to investigate the changes in C2 and C3 in the target group, the effective renal plasma flow (ERPF) was first determined for 10 of the 17 patients using intravenous I-131 labelled iodo-ortho-hippurate. A second reading was taken a week later. Eight of the 10 patients were found to have a relatively "higher" ERPF at the onset of acute myocardial infarction with an average reading of 450.1 +/- 168.9 ml/min, compared with the data obtained a week later (374.1 +/- 130.4 ml/min, p < 0.02). An inverse correlation existed between the percentage of "initial drop" in frequency moduli C2 and C3 in the power spectra of the radial pulses and the percentage of "initially higher" ERPF (r = -0.66 and -0.70, respectively, p < 0.05). It is concluded that there was a specific change in the power spectrum of the radial pulses which were recorded and analyzed noninvasively in patients with acute, uncomplicated myocardial infarction. Changes in the ERPF may exert an influence on the frequency moduli C2 and C3 of the power spectra of the radial pulses after heart attack, suggesting that the aorta and the closely organs may cause coupled oscillation. Theoretically this structure is equivalent to a resonance circuit.

Aged↗
PubMed2005

Intraortic pulse pressure is correlated with coronary artery stenosis.

There is increasing evidence that peripheral pulse pressure measured at the brachial artery is a good predictor of coronary heart disease. However, the relation between pulse pressure and angiographically demonstrated coronary artery stenosis has not been fully elucidated. We designed the present study to investigate the association of the various components of blood pressure, such as systolic pressure, diastolic pressure, and pulse pressure of both peripheral and central arteries with angiographically determined coronary artery stenosis. Levels of aortic systolic pressure, aortic diastolic pressure, aortic pulse pressure, peripheral systolic pressure, peripheral diastolic pressure, and peripheral pulse pressure were determined in 323 patients who underwent diagnostic coronary angiography. Of these 323 patients, 215 patients had significant organic coronary artery stenosis. Aortic pulse pressure was significantly higher in patients with coronary artery stenosis (P = 0.0050). Aortic diastolic pressure was lower in patients with coronary artery stenosis (marginally significant, P = 0.0462). However, no statistically significant difference was observed between other blood pressure components and coronary artery stenosis. Multivariate analyses showed that aortic pulse pressure was associated with coronary artery stenosis independently of aortic diastolic pressure. Moreover, aortic pulse pressure was positively correlated with the number of vessels involved (P = 0.0024). The results of the present study indicate that aortic pulse pressure is significantly and independently correlated with angiographically determined coronary artery stenosis.

Aorta↗
PubMed1981

The ocular pulse.

A recording applanation tonometer was used to examine the ocular pulse in normal subjects and patients with ocular hypertension, open angle glaucoma and low tension glaucoma. The mean pulse amplitude of right eyes of normal subjects was 2.84 mm Hg +/- 1.16 and 2.83 mm Hg +/- 1.18 for left eyes. Only 2% of subjects showed an interocular difference in pulse amplitude of more than 0.5 mm Hg. There were significant differences in pulse amplitude with refractive errors. Hypermetropic eyes had the largest pulse amplitude and myopic eyes the smallest. There was no significant correlation between pulse amplitude and intraocular pressure or age in normal subjects. The mean pulse amplitude of eyes with open angle glaucoma was significantly higher than that of normals. The mean pulse amplitude of a small number of eyes with ocular hypertension was significantly higher and eyes with low tension glaucoma had significantly lower pulse amplitudes than normal subjects.

Female↗
PubMed2006

An absent pulse is not sensitive for the early detection of peripheral arterial disease.

BACKGROUND: This study's objective was to determine the test characteristics of pedal pulse palpation in the diagnosis of peripheral arterial disease (PAD) when compared to the more widely recommended screening tool, the ankle-brachial index (ABI). METHODS: We screened patients > 50 years of age for PAD within primary care clinics in Houston. PAD was diagnosed by an ABI of <0.9. At each visit, pedal pulse palpation was performed for each leg. Of the patients who screened positive for PAD by ABI, we determined the sensitivity, specificity, and positive predictive value of pulse palpation. RESULTS: We enrolled 403 patients with a mean age of 63.8 +/- .36 years. The prevalence of PAD was 16.6% (67 patients total). Of the 45 patients with disease involving their left leg, 37 (82.2%) had a palpable pulse. Of the 37 patients with disease involving their right leg, 25 (67.6%) had a palpable pulse. The sensitivity of a non-detectable pulse for the diagnosis of PAD was 17.8% and 32.4% for the left leg and the right leg, respectively. The specificity of pulse palpation for the detection of PAD was 98.7% and 97.8% for the left leg and the right leg, respectively. CONCLUSIONS: Pulse palpation is not sensitive for the detection of PAD compared to ABI. More than two thirds of the patients within our cohort with PAD of either the left or right leg had a detectable pulse.

Age Distribution↗
PubMed2006

Is pulse palpation helpful in detecting atrial fibrillation? A systematic review.

BACKGROUND: Atrial fibrillation in the elderly is common and potentially life threatening. The classical sign of atrial fibrillation is an irregularly irregular pulse. OBJECTIVE: The objective of this research was to determine the accuracy of pulse palpation to detect atrial fibrillation. METHODS: We searched Medline, EMBASE, and the reference lists of review articles for studies that compared pulse palpation with the electrocardiogram (ECG) diagnosis of atrial fibrillation. Two reviewers independently assessed the search results to determine the eligibility of studies, extracted data, and assessed the quality of the studies. RESULTS: We identified 3 studies (2385 patients) that compared pulse palpation with ECG. The estimated sensitivity of pulse palpation ranged from 91% to 100%, while specificity ranged from 70% to 77%. Pooled sensitivity was 94% (95% confidence interval [CI], 84%-97%) and pooled specificity was 72% (95% CI, 69%-75%). The pooled positive likelihood ratio was 3.39, while the pooled negative likelihood ratio was 0.10. CONCLUSIONS: Pulse palpation has a high sensitivity but relatively low specificity for atrial fibrillation. It is therefore useful for ruling out atrial fibrillation. It may also be a useful screen to apply opportunistically for previously undetected atrial fibrillation. Assuming a prevalence of 3% for undetected atrial fibrillation in patients older than 65 years, and given the test's sensitivity and specificity, opportunistic pulse palpation in this age group would detect an irregular pulse in 30% of screened patients, requiring further testing with ECG. Among screened patients, 0.2% would have atrial fibrillation undetected with pulse palpation.

Atrial Fibrillation↗
PubMed1990

[The clinical relevance and reproducibility of pedal pulse palpation].

The object of the present investigation was to investigate the diagnostic information which can be obtained by pedal pulse palpation. This is done by relating the findings on pulse palpation to the measured distal systolic blood pressure and comparison of these results with those of previous examinations where the connection between the distal systolic blood pressure and the prognosis is illustrated. In addition, the reliability of pulse palpation was assessed by an inter-observer investigation. Fifty four patients (average age 66 years) suspected of occlusive arterial disease participated in the investigation. Three observers undertook pulse palpation on the foot in a randomized sequence. The pulse in a foot was defined as the pulse in the dorsalis pedis artery and/or the pulse in the posterior tibialis artery. After this, the distal systolic blood pressure was measured in the patients with the strain gauge technique. Considerable inter-observer agreement was found (kappa-values between 0.66 and 0.76). Provided an observer found the pulse present, severe occlusive arterial disease could be excluded (ankle index less than 50%, toe pressure less than or equal to 30 mmHg). Absence of pulse in a foot provides a high probability for an ankle index less than or equal to 90% and thus a high probability for presence of occlusive arterial disease, but the extent of this cannot, however, be described.

Adult↗
PubMed1982

[Intracranial pressure pulse waveform: considerations about its origin and methods of estimating intracranial pressure dynamics].

Epidural pulse waveform is important as an indicator of intracranial pressure (ICP) dynamics. In this study, the origin of epidural pulse and the clinical implication of its waveform were investigated, using anesthetized artificially ventilated dogs. For this purpose, a cortical artery and a vein were cannulated, and the pressures were recorded simultaneously with epidural pressure (EDP), epidural pulse waveform (EDP-WF), systemic arterial pressure measured in a carotid artery (SAP), central venous pressure (CVP) and electrocardiogram. EDP-WF is composed of several initial peaks and a small delayed peak on the descending limb. The former peaks were slightly delayed from the SAP pulse and were synchronous with the cortical arterial pulse. The latter peak was synchronous with the atrial "a" wave on CVP, but not with the cortical venous pulse. Moreover, the cortical venous pulse was quite similar to EDP-WF. These findings indicate that the pulsation of the brain may be generated by the pulsatile arterial blood flow into the brain, which also affected the pulsation of the cortical vein. The latter peak which was considered to be of venous origin may reflect the dynamics of venules in the brain, not of the cortical vein. Increase of ICP by constant inflation of the epidural balloon or inhalation of CO2 cause EDP-WF monotonous. It is possible that the transmission of arterial pulse into the brain was augmented because of the tightness of the brain or decrease of cerebral vascular tone, although the cortical arterial pressure was not significantly changed or was even slightly decreased. Using a bolus injection technique, the change of EDP-WF in cats was compared with volume-pressure response (VPR) and pulse pressure (PP) which are reported to be good indicators for ICP dynamics. At about 30mmHg, EDP-WF became monotonous while VPR or PP showed only linear relationships with EDP up to 50 to 60 mmHg. Therefore EDP-WF may provide useful information about ICP dynamics in a relatively lower pressure range which could not be detected by VPR or PP study.

Animals↗
PubMed1995

Applied recording force and noninvasive arterial pulses.

Arterial pressure pulses are often measured noninvasively, but the influence of external recording forces has not been well documented. Accordingly, the main goal was to delineate pulse contour and amplitude distortion with progressively compressive forces applied to an external transducer. Ten young normal male subjects were studied while supine. Pulses were recorded at the end of a normal expiration over a range of forces (0.45-4.29, 0.42N increments) applied in a randomized order over first the brachial and then the radial artery. Pulse contours were Fourier analyzed and harmonic powers were normalized to the peak power at the fundamental frequency. Brachial artery pulse amplitudes progressively decreased (p = 0.013), whereas, those at the radial artery peaked at a recording force of 1.79 +/- 0.01N (p < 0.001) and subsequently decreased parallel to the brachial data with larger forces. No significant pulse contour distortions occurred at either the brachial or radial artery with applied forces of up to 2.18 +/- 0.02 and 2.59 +/- 0.02N, respectively, as indicated by the similarity of the relative power for harmonics 2-7. Radial artery pulses were distorted at and beyond a force of 2.99 +/- 0.01N as indicated by the increased relative power of harmonics 3-7 (p < 0.05). Therefore, despite significant alterations in pulse amplitude, the relative shape of pulses remains similar over a large range of lower recording forces.

Adult↗
PubMed2000

Optimum setting of binomial pulses for magnetization transfer contrast.

Investigation of the cause of image artifacts generated by a magnetization transfer (MT) sequence using binomial-pulse trains led to findings of imperfections in the pulses. These imperfections caused anomalous direct saturation of the free water, which was localized due to the static magnetic field inhomogeneity. In the case of single binomial pulses a loss of overall MT response across the field of view results. Two methods of correcting the imperfections and removing the artifact have been established using interactive adjustment of sub-pulse lobes and phase swapping of pulse trains. These imperfections may be present in many systems and may have led to erroneous judgements of the value of binomial pulses for MT imaging. A technique for interrogating the frequency spectrum of the binomial-pulse train has been utilized, allowing its optimization. The use of accurate and optimized binomial pulses may yet prove to be preferable to pulsed off-resonance methods for quantitative, clinical MT imaging.

Artifacts↗