Longitudinal displacement and intramural shear strain of the porcine carotid artery undergo profound changes in response to catecholamines.

The effects of catecholamines on longitudinal displacements and intramural shear strain of the arterial wall are unexplored. Therefore, the common carotid artery of five anaesthetized pigs was investigated using an in-house developed noninvasive ultrasonic technique. The study protocol included intravenous infusion of low-dose epinephrine (ß-adrenoceptor activation), as well as intravenous boluses of norepinephrine (α-adrenoceptor activation). Further, the effects of ß-blockade (metoprolol) were studied. There were significant positive correlations between pulse pressure and longitudinal displacement of the intima-media complex (r = 0.72; P < 0.001), as well as between pulse pressure and intramural shear strain (r = 0.48; P < 0.001). Following administration of norepinephrine, the longitudinal displacement of the intima-media complex and intramural shear strain profoundly increased (median 190%, range 102-296%, and median 141%, range 101-182%, respectively, compared with baseline), also when given during ß-blockade (median 228%, range 133-266%, and median 158%, range 152-235%, respectively). During infusion of low-dose epinephrine, the longitudinal displacement of the intima-media complex and intramural shear strain decreased (median 88%, range 69-122%, and median 69%, range 47-117%, respectively, compared with baseline). In conclusion, the present study shows, for the first time, that the longitudinal displacement and intramural shear strain of the porcine carotid artery undergo profound changes in response to catecholamines. Increase in longitudinal displacements seems to be strongly related to α-adrenoceptor activation. Thus metoprolol is insufficient to counteract a profound increase in longitudinal displacement and intramural shear strain following a surge of norepinephrine.

Swedish clinical guidelines--prevention and management of metabolic risk in patients with severe psychiatric disorders.

Individuals with severe psychiatric disorders are more likely than the population at large to develop metabolic derangements such as overweight and diabetes. Cardiovascular disease is also more frequently seen in this group. Contributing factors may include inappropriate diet or lack of physical activity, but antipsychotic medication may also play a role. Seven Swedish specialist medical societies have collaborated in formulating a set of concise clinically applicable guidelines-reproduced here in modified form-for the prevention and management of metabolic risk in this patient group. The importance of implementation is emphasized.

Effects of a global health and risk assessment tool for prevention of ischemic heart disease in an individual health dialogue compared with a community health strategy only results from the Live for Life health promotion programme.

OBJECTIVE: To evaluate the effect of an individual health dialogue on health and risk factors for ischemic heart disease in addition to that of a community based strategy. METHOD: Inhabitants in four communities in the area of Skaraborg, Sweden were invited to a health examination including a health dialogue both at the age of 30 and 35 (target communities). In another four communities inhabitants were invited only at the age of 35 (reference communities). Health and risk factors in 35-year old inhabitants in the target communities who participated in the health dialogue in 1989-1991 and 1994-1996 were analysed and compared with 35-year olds in the reference communities participating during the same periods of time. RESULTS: Inhabitants in communities where there had been a previous individualised health intervention programme had, on the community level, a more favourable development concerning dietary habits, mental stress, body mass index, waist circumference, cholesterol, blood pressure and metabolic risk profile compared to inhabitants in communities with only a community based health intervention programme. CONCLUSIONS: An individual lifestyle oriented health dialogue supported by a global health and risk assessment pedagogic tool seems to be more effective than a community health strategy only.

Primary care patients' attitudes to priority setting in Sweden.

OBJECTIVE: To analyse attitudes to priority setting among patients in Swedish primary healthcare. DESIGN: A questionnaire was given to patients comprising statements on attitudes towards prioritizing, on the role of politicians and healthcare staff in prioritizing, and on patient satisfaction with the outcome of their contact with primary healthcare (PHC). SETTINGS: Four healthcare centres in Sweden, chosen through purposive sampling. PARTICIPANTS: All the patients in contact with the health centres during a two-week period in 2004 (2517 questionnaires, 72% returned). MAIN OUTCOMES: Patient attitudes to priority setting and satisfaction with the outcome of their contact. RESULTS: More than 75% of the patients agreed with statements like "Public health services should always provide the best possible care, irrespective of cost". Almost three-quarters of the patients wanted healthcare staff rather than politicians to make decisions on priority setting. Younger patients and males were more positive towards priority setting and they also had a more positive view of the role of politicians. Less than 10% of the patients experienced some kind of economic rationing but the majority of these patients were satisfied with their contact with primary care. CONCLUSIONS: Primary care patient opinions concerning priority setting are a challenge for both politicians and GPs. The fact that males and younger patients are less negative to prioritizing may pave the way for a future dialogue between politicians and the general public.

An echolocation visualization and interface system for dolphin research.

The present study describes the development and testing of a tool for dolphin research. This tool was able to visualize the dolphin echolocation signals as well as function as an acoustically operated "touch screen." The system consisted of a matrix of hydrophones attached to a semitransparent screen, which was lowered in front of an underwater acrylic panel in a dolphin pool. When a dolphin aimed its sonar beam at the screen, the hydrophones measured the received sound pressure levels. These hydrophone signals were then transferred to a computer where they were translated into a video image that corresponds to the dynamic sound pressure variations in the sonar beam and the location of the beam axis. There was a continuous projection of the image back onto the hydrophone matrix screen, giving the dolphin an immediate visual feedback to its sonar output. The system offers a whole new experimental methodology in dolphin research and since it is software-based, many different kinds of scientific questions can be addressed. The results were promising and motivate further development of the system and studies of sonar and cognitive abilities of dolphins.

Evaluation of an ultrasonic echo-tracking method for measurements of arterial wall movements in two dimensions.

The longitudinal movement of blood vessel walls has so far gained little or no attention, as it has been presumed that these movements are of a negligible magnitude. However, modern high-resolution ultrasound scanners can demonstrate that the inner layers of the arterial wall exhibit considerable movements in the longitudinal direction. This paper evaluates a new, noninvasive, echo-tracking technique, which simultaneously can track both the radial and the longitudinal movements of the arterial wall with high resolution in vivo. Initially, the method is evaluated in vitro using a specially designed ultrasound phantom, which is attached to and moved by an X-Y system, the movement of which was compared with two high-resolution triangulation lasers. The results show an inaccuracy of 2.5% full scale deflection (fsd), reproducibility of 12 microm and a resolution of 5 microm, which should be more than sufficient for in vivo studies. The ability of the method is also demonstrated in a limited in vivo study in which a preselected part of the inner vessel wall of the right common carotid artery of a healthy volunteer is tracked in two dimensions over many cardiac cycles. The results show well reproducible x-y movement loops in which the recorded radial and longitudinal movements both are of the magnitude millimetre.

Profound increase in longitudinal displacements of the porcine carotid artery wall can take place independently of wall shear stress: a continuation report.

The mechanisms underlying longitudinal displacements of the arterial wall, that is, displacements of the wall layers along the artery, and the resulting intramural shear strain remain largely unknown. We have already found that these displacements undergo profound changes in response to catecholamines. Wall shear stress, closely related to wall shear rate, represents the viscous drag exerted on the vessel wall by flowing blood. The aim of the work described here was to study possible relations between the wall shear rate and the longitudinal displacements. We investigated the carotid arteries of five anesthetized pigs in different hemodynamic situations using in-house developed non-invasive ultrasound techniques. The study protocol included administration of epinephrine, norepinephrine and ß-blockade (metoprolol). No significant correlation between longitudinal displacement of the intima-media complex and wall shear rate was found. This result suggests that one or multiple pulsatile forces other than wall shear stress are also working along arteries, strongly influencing arterial wall behavior.

The history of echocardiography.

Following a brief review of the development of medical ultrasonics from the mid-1930s to the mid-1950s, the collaboration between Edler and Hertz that began in Lund in 1953 is described. Using an industrial ultrasonic flaw detector, they obtained time-varying echoes transcutaneously from within the heart. The first clinical applications of M-mode echocardiography were concerned with the assessment of the mitral valve from the shapes of the corresponding waveforms. Subsequently, the various M-mode recordings were related to their anatomical origins. The method then became established as a diagnostic tool and was taken up by investigators outside Lund, initially in China, Germany, Japan and the USA and, subsequently, world-wide. The diffusion of echocardiography into clinical practice depended on the timely commercial availability of suitable equipment. The discovery of contrast echocardiography in the late 1960s further validated the technique and extended the range of applications. Two-dimensional echocardiography was first demonstrated in the late 1950s, with real-time mechanical systems and, in the early 1960s, with intracardiac probes. Transesophageal echocardiography followed, in the late 1960s. Stop-action two-dimensional echocardiography enjoyed a brief vogue in the early 1970s. It was, however, the demonstration by Bom in Rotterdam of real-time two-dimensional echocardiography using a linear transducer array that revolutionized and popularized the subject. Then, the phased array sector scanner, which had been demonstrated in the late 1960s by Somer in Utrecht, was applied to cardiac studies from the mid-1970s onwards. Satomura had demonstrated the use of the ultrasonic Doppler effect to detect tissue motion in Osaka in the mid-1950s and the technique was soon afterwards applied in the heart, often in combination with M-mode recording. The development of the pulsed Doppler method in the late 1960s opened up new opportunities for clinical innovation. The review ends with a mention of color Doppler echocardiography. (E-mail:

Movement artefact suppression in blood perfusion measurements using a multifrequency technique.

The standard way of suppressing movement artefacts in Doppler measurements is by means of a high-pass filter. This is because artefacts usually are of high amplitude, but have low frequencies. The immediate drawback is, then, that low-velocity blood flow is also filtered out. In this paper, a method to reduce movement artefacts in blood perfusion measurements is proposed, using simultaneous transmission and reception of multiple frequencies in a continuous-wave Doppler system. It is shown that Doppler signals originating from blood may be considered uncorrelated for a large enough frequency separation between channels, and tissue movements are more correlated. By subtracting perfusion estimates obtained by time-domain processing, correlated signals can be suppressed. The subtraction algorithm is shown to produce a linear perfusion estimate, but with twice the standard deviation compared to an estimate obtained by simply averaging channels. Movement artefacts in both in vitro and in vivo models are shown to be reduced by the algorithm. Imbalance between channels does, however, cause the artefacts to be only partly reduced. The problem can be alleviated by filtering the signals prior to subtraction, but this results in a nonlinear estimate, especially for large time constants in the filter. Some amount of filtering can still be desirable to suppress partly correlated artefacts, even if identical time-domain processing units are implemented, as could be done digitally.

A new non-invasive ultrasonic method for simultaneous measurements of longitudinal and radial arterial wall movements: first in vivo trial.

During recent years, the radial movement of the arterial wall has been extensively studied, and measurements of the radial movement are now an important tool in cardiovascular research for characterizing the mechanical properties of the arterial wall. In contrast, the longitudinal movement of vessels has gained little or no attention as it has been presumed that this movement is negligible. With modern high-resolution ultrasound, it can, however, be seen that the intima-media complex of the arterial wall moves not only in the radial direction, but also in the longitudinal direction during pulse-wave propagation. This paper describes a new non-invasive ultrasonic method that is able to measure simultaneously two dimensionally arterial vessel wall movements. The method is demonstrated in a limited in vivo trial. Results from the in vivo trial show that, apart from the well-known radial movement, there is a distinct longitudinal movement in the human common carotid artery with, in this case, the intima-media complex moving substantially as compared with the region of the tunica adventitia. Two-dimensional evaluation of the vessel-wall movements, taking not only the radial movement, but also the longitudinal movement into account, may provide novel information of importance in the evaluation of vessel-wall function.

Frequency dependence of speckle in continuous-wave ultrasound with implications for blood perfusion measurements.

Speckle in continuous wave (CW) Doppler has previously been found to cause large variations in detected Doppler power in blood perfusion measurements, where a large number of blood vessels are present in the sample volume. This artifact can be suppressed by using a number of simultaneously transmitted frequencies and averaging the detected signals. To optimize the strategy, statistical properties of speckle in CW ultrasound need to be known. This paper presents analysis of the frequency separation necessary to obtain independent values of the received power for CW ultrasound using a simplified mathematical model for insonation of a static, lossless, statistically homogeneous, weakly scattering medium. Specifically, the autocovariance function for received power is derived, which functionally is the square of the (deterministic) autocorrelation function of the effective sample volumes produced by the transducer pair for varying frequencies, at least if a delta correlated medium is assumed. A marginal broadening of the modeled autocovariance functions is expected for insonation of blood. The theory is applicable to any transducer aperture, but has been experimentally verified here with 5-MHz, 6.35-mm circular transducers using an agar phantom containing small, randomly dispersed glass particles. A similar experimental verification of a transducer used in multiple-frequency blood perfusion measurements shows that the model proposed in this paper is plausible for explaining the decorrelation between different channels in such a measurement.

The options of the management of self-monitoring of blood glucose in primary health care centres by the diabetes nurses and patients.

The aims of the present study were to investigate the diabetes nurse specialists (DNS) practice according to the local diabetic guideline, to study the DNSs' opinion of self-monitoring of blood glucose (SMBG) and prescription of test-strips, to investigate the patients' opinions and habits when using SMBG. Users of SMBG (n=533 patients') and all DNSs (n=25) were telephone interviewed. Only a few DNSs used local guidelines, the majority had their own prescribing strategy of SMBG. In conclusion, DNSs were aware of the guidelines but did not use them to support their decision regarding the reasons for prescribing SMBG or not. For diabetes patients, reassurance was the most important issue in having access to SMBG, despite the fact that one-third retested but did not change their behaviour and nearly 15% contacted their DNS for advice.