A pilot study evaluating the use of ABCD2 score in pre-hospital assessment of patients with suspected transient ischaemic attack: experience and lessons learned.

Background: Suspected transient ischaemic attack (TIA) is a common presentation to emergency medical services (EMS) in the United Kingdom (UK). Several EMS systems have adopted the ABCD2 score to aid pre-hospital risk stratification and decision-making on patient disposition, such as direct referral to an Emergency Department or specialist TIA clinic. However, the ABCD2 score, developed for hospital use, has not been validated for use in the pre-hospital context of EMS care.

Ventricular aneurysm: pressure-volume relationships of a physical model.

Static pressure-volume characteristics were determined in elastic sacs with aneurysms of varying radius and wall thickness. Increasing the radius of an aneurysm lowered the maximal pressure (Pmax) which could be generated by contraction and deformed the pressure-volume curves compared with an intact sac of the same thickness. Progressive decrease in the wall thickness of an aneurysm of a given size resulted in progressive loss of pressure generated by any degree of filling.

Effect of posture on arterial pressures, timing of the arterial sounds and pulse wave velocities in the extremities.

We have recorded systolic and diastolic blood pressure, and the intervals between the QRS complex of the electrocardiogram and the Korotkoff arterial sound at systolic and diastolic pressure (QKs and QKd, respectively), at the brachial and posterior malleolar arteries, for normal subjects in the supine, standing, or head-down positions on a tilt table. These data make it possible to calculate an apparent mean pulse wave velocity. Results indicate: (1) when the subject is supine (0 degrees), brachial and posterior malleolar artery blood pressures are virtually identical; (2) upon standing (+90 degrees), both systolic and diastolic pressures in the foot are elevated by a mean of approximately 70 mm Hg, whereas brachial artery systolic pressure is unaffected and brachial diastolic pressure is raised 7 mm of mercury; (3) conversely, in the head-down (feet-up) position (-30 degrees) the blood pressure in the foot was decreased approximately 20 mm of mercury, whereas the brachial arterial pressure is again unaffected; (4) as one changes from the head-down to the supine to the standing positions, the mean QKs interval at the brachial artery was increased by 5 and 15 msec, respectively; (5) conversely, the arrival of the pulse wave in the leg was hastened, with QKd decreasing by 7 and then 18 msec.

Vasomotor escape from adrenaline, noradrenaline or acetylcholine in the dog hind limb.

The noradrenaline, adrenaline and acetylcholine-induced vasoregulatory escape was demonstrated in the vascular bed of intact of skinned and denervated dog's hind limb. Escape effect disappeared or decreased markedly under elevation tissue pressure in the examined hind limb. These data indicate that tissue pressure factor may take part in the mechanism of the escape phenomenon.

Ventilatory effects on pulmonary vascular inflow and outflow patterns.

Ventilation of an isolated lung lobe modifies the rate of inflow into its pulmonary artery (Murao and Rodbard, 1971). The present studies show that ventilation also influences the rate of outflow from the pulmonary vein in a manner which differs significantly from the effects on the rate of inflow into the pulmonary artery. Since this difference between instantaneous inflow and outflow rates affects the calculation of vascular conductance (resistance) and its interpretation we have compared and analysed the effects of ventilation on simultaneous flow patterns in the pulmonary artery and vein.

Effects of treadmill exercise on the timing of the heart and arterial sounds, and the slope of the brachial arterial pulse wave.

An indirect, noninvasive method of sphygmorecording was used to study the effect of exercise on a number of cardiac parameters, including heart rate, blood pressure, the timing of the heart and Korotkoff arterial sounds, and the slope (dP/DT) of the brachial arterial pressure wave. The QKd interval is a sensitive and reliable indicator of the cardiovascular response to exercise stress, and can be used to follow the rate of return to basal levels. Changes in the QKd can occur even in the presence of fixed heart rate.

Delayed timing of heart and arterial sounds in patients with implanted pacemakers.

We have recorded the timing of the heart sounds and the arterial sounds with reference to the onset of each cardiac cycle in 16 patients before and after implantation of a pacemaker prosthesis, and in an additional 18 patients after pacemaker implantation only. The interval between the QRS complex and the Korotkoff sound at diastolic pressure (QKd) is markedly prolonged, from 206 to 294 msec., a change corresponding to 10 standard errors of the mean difference.

Arterial stenosis, pressure, and flow.

The interaction between the effects of an arterial stenosis and postocclusion hyperemia was studied in a model of the capillaron system. A capillaron is a module consisting of soft-walled permeable vessels (capillaries) in a compliant capsule. Stenosis reduced flow in accord with arterial cross-sectional area.

Pulmonary artery dissection and rupture in Eisenmenger's syndrome.

A patient with ventricular septal defect and pulmonary arterial hypertension (Eisenmenger's syndrome) associated with aortic coarctation with follow-up for 19 years, and with rupture of an aneurysmatic pulmonary artery is described. An incident of extreme fright with a possible transient systemic hypertension may have precipitated the dissection of the pulmonary arterial intima and the rupture.

Mathematical formulation of post-occlusion hyperaemia and autoregulation of blood flow in the capillaron model.

A mathematical formulation of the blood flow behaviour through a capillaron model is described. The formulation is applied to the analysis of post-occlusion (reactive) hyperaemia and autoregulation.

Factors affecting the transvalvar pressure difference in a hydraulic model of aortic stenosis.

Mechanical factors that can modify the peak transvalvar pressure differences (delta P) in aortic stenosis were evaluated in a model. A latex rubber sac simulated the ventricle. Expansion of the walls of the sac by means of a negative pressure applied to its outer wall introduced a measure volume into the sac and placed the wall materials under tension.

Venous pressure and exercise tolerance.

Compared to the number of contractions obtained when a blood pressure cuff on the upper arm was at zero pressure, inflation of the cuff to pressures ranging between 5 and 40 mm Hg resulted in an augmentation of the number of hand contractions that could be performed prior to the development of ipsilateral severe fatigue or intolerable pain. Cuff pressures of 60 mm Hg reduced the number of contractions below the control level. These results are consistent with the concept that exercise during venous congestion facilitates the washout of the toxic catabolite presumed to be produced during muscular contraction.

Clinical utility of the simultaneous recording of heart and Korotkoff sounds.

Heart and arterial sounds and murmurs for a sequence of as many as 100 successive beats are recorded on a single print. The apparatus consists of a cathode ray oscilloscope, a Q-wave trigger to release the beam, a vertical axis which is connected to the blood pressure cuff, and an intensity modulation circuit which determines the intensity of the beam at each instant. This arrangement eliminates the baseline and thereby permits the display of low intensity acoustic signals.

Valve dynamics.

Flow between two contiguous elastic sheets (valve leaflets) generates one of two types of behavior. At low pressure differences, e.g.

Orientation of the fascicles of the ventricular myocardium.

A new technique was developed to examine the arrangement of the fascicles of the myocardium. Liquid plastic was injected intramurally into the free walls and the septum of more than 300 hearts of mammals and birds. After the plastic hardened, the tissues were digested in alkali, thereby releasing a plastic cast which had been formed in the myocardium.

Compartments and suborgans of the ventricular myocardium.

Color-coded liquid plastic was injected intraparenchymally (not into the blood vessels) into more than 300 hearts of homeotherms--including dog, cat, sheep, beef, horse, mammalian dolphins, chickens, turkeys, etc. The organization of the hearts of all these species appears to be similar. After injection of a heart segment such as the right ventricular free wall, corrosion (digestion) of the heart in strong alkali releases the case of only this free wall, and of the lymphatic vessels which drain this segment.

Selective staining of fibrous connective tissue capsules and lymphatics: an evaluation of "interstitial" fluids.

Ringer's solution containing ferrocyanide ion was infused into the arterial system of lumbs. Some of these ions filtered across the blood capillary wall into the adjacent extracapillary fluids, from which diffusion caused these ions to enter the wall of the enclosing epimysial capsule. Ringer's solution containing ferric ion was then injected into the parenchyma (not intravascularly).

Functional anatomy of the lymphatic fluids and pathways.

The present sets of studies indicate that the fibrous capsule which encloses each tissue module divides the interstitial fluids into an intracapsular pool, and an extracapsular pool. Fluid that filters out of the capsules into the extracapsular clefts is the source of the lymph. Because of the limited permeability of the capsular barrier the composition of lymph differs from that of the capillary ultrafiltrate.