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Biomedical subjects

J R Holmes

Publications and source records attributed to J R Holmes.

At least 37 records · Page 2Linked to original sources
PubMed1985

Milrinone in congestive heart failure: observations on ambulatory ventricular arrhythmias.

Milrinone is a potent non-catecholamine, non-glycoside inotropic agent that can improve hemodynamic performance and functional capacity in patients with severe congestive heart failure. However, the potential effect of chronic inotropic stimulation on ventricular arrhythmias in patients with heart failure requires evaluation. We compared 24-hour ambulatory ECGs before and 2 to 4 weeks after initiation of chronic milrinone therapy in 20 patients with severe congestive heart failure (mean cardiac index 1.79 +/- 0.43 L/min/m2). A greater than tenfold increase in simple ventricular premature complex (VPC) density, a greater than tenfold increase in complex VPC form density, or an increase from 0 to greater than 5 episodes per 24 hours of any complex VPC form occurred in 35% (7 of 20) of patients. A greater than tenfold reduction in simple VPC density was noted in 5% (1 of 20), while 60% (12 of 20) of the study group had no significant change in ventricular arrhythmia profile on milrinone. The hemodynamic and functional response to milrinone, as well as entry hemodynamic profiles, were unrelated to the change in frequency or complexity of ventricular arrhythmias during therapy. Thus, milrinone therapy in congestive heart failure may be associated with the development of VPC complexity and with a significantly increased density of complex VPC forms.

Administration, Oral↗
PubMed1985

The dowelklip: a device for dowel pin placement.

While no system of dowel pin placement satisfies all the desired requirements in every situation, the dowelklip is an original design that meets most of the requirements for many routine treatment procedures. For dentists who do not do a large enough volume of fixed restorative procedures to justify the expense of complex die positioning systems but are dissatisfied with sticky wax and match sticks, the dowelklip offers an alternative approach.

Denture Design↗
PubMed1985

Observations on seven cases of mitral insufficiency in the horse.

Observations on seven cases of mitral insufficiency are described. Three of the horses had recent histories of cardiac failure and formed a separate group in which there were marked haemodynamic changes which varied in relation to heart rate but were associated with pulmonary hypertension, elevated right ventricular pressure and low peak left ventricular pressure. In the other four horses the heart appeared to be compensating at rest but to be unable to cope with severe exertion. On auscultation, a widespread pansystolic murmur and a prominent third heart sound were characteristic of the left ventricular volume overload. Microscopic changes were found in one left papillary muscle. The possibility that changes in the position of the papillary muscles consequent upon left ventricular dilatation may lead to or exaggerate mitral valve eversion is discussed.

Animals↗
PubMed1984

Occurrence of hepatitis A, B, and non-A/non-B in the United States. CDC sentinel county hepatitis study I.

To determine the relative occurrence of hepatitis A, B, and non-A/non-B in the United States, serum samples and epidemiologic data were collected from patients with hepatitis in five selected counties. Overall, 41, 33, and 26 percent of the patients had hepatitis A, hepatitis B, and hepatitis non-A/non-B, respectively. The incidence, especially of hepatitis A, varied considerably. All three types of hepatitis occurred more frequently in those 15 to 44 years of age. Hepatitis A predominated in those less than 15 years of age and non-A/non-B predominated in those older than 44 years. There was a male predominance (65 to 62 percent) for hepatitis A and hepatitis B, but non-A/non-B occurred equally in both sexes. There was no seasonal pattern for any type. Risk factors for hepatitis A were previous contact with a patient with hepatitis (26 percent), homosexual (male) preference (15 percent), and day-care center contact (11 percent). For hepatitis B, risk factors included drug use (26 percent), previous contact with an infected person (22 percent), homosexual preference (12 percent), and a health-care occupation (12 percent). For hepatitis non-A/non-B, risk factors included drug use (16 percent), transfusion (12 percent), and previous contact with an infected person (12 percent). Previous hospitalization appeared to be a risk factor for both hepatitis B and hepatitis non-A/non-B.

Adolescent↗
PubMed1984

Isokinetic strength characteristics of the quadriceps femoris and hamstring muscles in high school students.

The purpose of this study was to determine the isokinetic strength of the quadriceps femoris and hamstring muscles in high school-aged students. Forty-seven 15- to 18-year-old high school volunteers served as subjects. Data were gathered on each subject by a questionnaire, lower extremity musculoskeletal assessment, and isokinetic testing of the two muscle groups at 60 degrees/sec and 180 degrees/sec. This study found no age effect on peak torque and no significant differences in peak torque between dominant and nondominant limbs. Significant differences (p less than .001) occurred between the isokinetic strength of male and female subjects. The average hamstring muscle to quadriceps femoris muscle torque ratio was 57 percent at 60 degrees/sec and 70 percent at 180 degrees/sec. A value of foot pounds of torque per kilogram of body weight was provided as a guideline for clinicians. This investigation supports several findings already reported for other age groups.

Adolescent↗
PubMed1984

Three cases of ruptured mitral valve chordae in the horse.

The paper describes clinical observations in three horses with ruptured mitral valve chordae. Horses with ruptured mitral valve chordae may have a history of sudden onset of acute distress with predominantly respiratory symptoms. On auscultation there will be a widespread pansystolic murmur with an extension of the area of cardiac auscultation. The third heart sound may be very pronounced and unduly prolonged, associated with high volume flow during early ventricular filling in diastole. However, these sounds are not specific for chordal rupture--they are typical of severe mitral regurgitation. The electrocardiogram may show predominantly backward spatial vectors during ventricular depolarisation. The condition gives rise to left ventricular volume overload and pulmonary hypertension would be expected in horses showing signs of cardiovascular disturbance or those recently affected. Care is necessary during post mortem examination to avoid cutting through the mitral valve before a proper assessment has been made of the chordal insertions.

Animals↗
PubMed1984

Computer processing of transaortic valve blood pressures in the horse using the first derivative of the left ventricular pressure trace.

A method is described of processing transaortic valve pressures in the horse using the first derivative of the left ventricular pressure to define the beginning and end of each systolic complex. To determine the beginning of each systole three definitions of left ventricular end diastolic pressure (LVEDP), based on a 100, 150 or 200 mmHg/sec rate of left ventricular diastolic pressure rise, were evaluated. These definitions were also evaluated for their ability to determine isovolumic contraction time (ICT) and pulse interval. The best of these, LVEDP 150, was defined as the last point in diastole before a rate of rise of left ventricular pressure (LVdP/dt) equal to or exceeding 150 mmHg/sec sustained over 44 msecs. The end of left ventricular ejection was estimated from the left ventricular pressure trace as the point at which--LVdP/dtmax occurred. There was good agreement between the values of left ventricular ejection time (LVET) measured to the incisura of the aortic pressure trace and LVET calculated to the time of--LVdP/dtmax (r = 0.991). The importance of visually examining the waveforms before committing them to automatic processing is emphasised.

Animals↗
PubMed1984

Observations on structure and function of the equine mitral valve.

The anatomy of the equine mitral valve and certain variations observed in 60 adult horses are described. The functional role of this valve, sited between the left atrium and the high pressure-generating left ventricle, is discussed in relation to its anatomical structure. A method of examining the left side of the heart post mortem is described.

Animals↗
PubMed1984

Interrelationship of some electrocardiogram amplitudes, time intervals and respiration in the horse.

The relationship of the scalar and vector magnitudes of the QRS waveform to RR, PR and respiration was examined in 10 horses in regular rhythm using an orthogonal lead system. There were no significant changes in the durations of RR and PR with respiration. The amplitudes of the scalar variables XR and YR were directly related and that of XQ (or XS) and ZR were inversely related to PR in this group of horses. The peak spatial vector magnitude and its H-plane angle were directly related to PR and inversely related to RR. The effect of inspiration on the QRS was a decrease in YR and ZR, an increase in YS and peak spatial vector magnitude and a reduction in its angle of elevation. Examined over the 10 horses these changes were only small (1.8 to 3.8 per cent) and considered to be not significant clinically. The possible mechanisms of the relationship to PR and RR and the effect of respiration on the QRS waveform are discussed. The results suggest the possibility of a vagal effect on intraventricular conduction. The effect of respiration was shown to be independent of this effect and it might be due to changes in lung electrical conductivity during respiration.

Animals↗
PubMed1984

Relationships of left side systolic time intervals to beat-by-beat heart rate and blood pressure variables in some cardiac arrhythmias of the horse.

Systolic time intervals (STIs), isovolumic contraction time (ICT) and left ventricular ejection time (LVET) were recorded from seven horses with supraventricular arrhythmia. The STIs were measured over a number of beats (33 to 100) directly from the left ventricular (LV) and aortic (Ao) pressure contours which were recorded simultaneously using two catheter-mounted transducers. ICT was significantly (P less than 0.01) and directly related to beat-by-beat heart rate (HR = 60/pulse interval) and LVET was significantly (P less than 0.01) and inversely related to heart rate in each of five horses. In two horses with atrial fibrillation, LVET declined much more rapidly at heart rates greater than 70 to 80 beats minute-1 which suggested the possibility of impaired ventricular filling above this heart rate range in this arrhythmia. ICT, LVET, LVET/ICT and mechanical systole (MS = ICT + LVET) were regressed against a number of pressure parameter and also against heart rate. ICT was directly related to aortic end diastolic pressure (AoEDP) and inversely related to left ventricular end diastolic pressure (LVEDP) and LV dP/dtmax. LVET was directly related to aortic systolic pulse pressure (SPP = Peak AoP-AoEDP) and inversely related to AoEDP. It was related to heart rate in only two out of the seven horses. LVET/ICT was most strongly and inversely related to AoEDP. It was directly related to LVEDP, SPP and to LV dP/dtmax but was not consistently related to heart rate. The relationship of these variables to LVET/ICT reflected largely their separate relationships to ICT and LVET.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Beat-to-beat variability in QRS potentials recorded with an orthogonal lead system in horses with second degree partial A-V block.

Beat-to-beat variation in the amplitude of the QRS waveform from 13 horses with second degree partial atrioventricular block was examined using an orthogonal lead (X,Y,Z) system. The peak positive deflections (XR, YR and ZR) and peak negative deflections (XQS, YS and ZQ) were regressed against PR and RR intervals. XQS was used to indicate that the peak negative deflection in X could have been a Q or S wave. XR and YR were directly related to PR (P less than 0.001) and XQS and YS were inversely related to PR (P less than 0.001). YR was also directly related to RR (P less than 0.001) but not so strongly as to PR. YS was inversely related to RR (P less than 0.001). Neither ZQ nor ZR were related to PR or RR. The findings in this study suggest that vagal tone can affect intraventricular conduction in the horse.

Animals↗
PubMed1983

Effect of cardiac arrhythmia on left ventricular and aortic blood pressure parameters in the horse.

Transaortic blood pressures were recorded in seven horses using catheter mounted transducers during various types of supraventricular arrhythmia. Changes in left ventricular (LV) and aortic (Ao) pulse contours were associated with variation in pulse interval (PI). When PI lengthened there was a rise in LV end diastolic pressure (LVEDP) associated with a prolonged filling time. In contrast, a long PI resulted in a reduced end diastolic Ao pressure (AoEDP) due to a prolonged arterial 'run off'. LVdP/dt max representing the peak rate of rise of pressure during the isovolumic contraction period was not consistently affected by changes in PI. Stepwise linear regression was used to examine the simultaneous relationships of a number of variables derived from the LV and Ao contours. Peak LV pressure (LVPp) was directly related to AoEDP (seven of seven horses) and LVEDP (four of seven). Ao systolic pulse pressure (SPP) was directly related to LVEDP (four of seven) and inversely related to AoEDP (three of seven). Neither LVPp nor SPP were consistently related to LVdP/dt max. The peak positive gradient between LV and Ao pressures was inversely related to AoEDP (six of seven) and directly related to LVEDP and LVdP/dt max (three of seven). The peak rate of rise of the Ao pressure contour during ejection (AodP/dt max) was inversely related to AoEDP (seven of seven) and directly related to LVEDP (four of seven). It was also directly related to LVdP/dt max in four horses but was inversely related in one. The peak rate of fall of the LV pressure contour during relaxation (-LVdP/dt max) was directly related to LVPp (five of seven).

Animals↗
PubMed1982

Sir Frederick Smith Memorial Lecture. A superb transport system--the circulation.

This paper discusses certain aspects of circulatory physiology, including foetal circulation and the role of the thorax, and gives parameters for total blood volume, cardiac output, stroke volume and the distribution of blood between the pulmonary and peripheral circulation within the horse. The reader is taken on a journey around the circulatory system, beginning in the left atrium, into which richly oxygenated blood runs from the pulmonary veins. From here the blood is squeezed via the mitral valve into the left ventricular pump, where it is forced under high pressure through the peripheral circulation, the arterioles and capillaries, to collect, deoxygenated and under much lower pressure, into the venules and veins. The pumping action of the muscles and the negative intrathoracic pressure help to draw the blood back up to the right atrium, itself exerting a suction effect on the great veins. The blood is then expelled from the right ventricle into the low resistance, high capacitance pulmonary circuit, where it picks up oxygen, releases carbon dioxide and returns to the left atrium.

Animals↗
PubMed1981

Emetic food poisoning caused by Bacillus cereus.

Symptoms of acute food poisoning developed in eight members of a group who ate lunch at a cafeteria. After brief incubation periods, all affected individuals complained of nausea and abdominal cramps. Four persons promptly experienced vomiting. None of those affected was found to have fever and all recovered with 48 hours. Epidemiologic investigation incriminated macaroni and cheese as a cause of the illness and samples of this food contained large numbers of Bacillus cereus. Previous outbreaks of B cereus emetic food poisoning have been associated with consumption of contaminated fried rice and may occur after ingestion of other foods.

Adult↗
PubMed1979

Phonocardiography in the horse: 1. The intracardiac phonocardiogram.

Using microtransducers, the intracardiac phonocardiogram was recorded in 8 horses from the right heart and in 6 of them also on the left side. All 4 heart sounds were recorded but not in all sites. Their timing was related to pressure events. Systolic ejection murmurs were recorded in both the pulmonary artery and the aorta. Diastolic murmurs were recorded in 2 horses with aortic regurgitation, with maximum amplitude in the left ventricle. The findings were similar to those reported in man and agree with some of the recent concepts on heart sound production.

Animals↗