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Biomedical subjects

S Sire

Publications and source records attributed to S Sire.

32 records · Page 2Linked to original sources
PubMed1993

Effect of nifedipine on splanchnic and pulmonary vascular capacitance.

This study examines the hypothesis that nifedipine may increase splanchnic vascular capacitance and thus change the distribution of blood between the splanchnic and pulmonary circulation in heart failure patients. Relative regional blood volumes were determined by equilibrium blood pool scintigraphy during a 10 min baseline period and for 30 min after nifedipine 20 mg sublingually, with simultaneous recordings of systemic and pulmonary arterial pressures, hepatic venous wedge pressure, and cardiac output. Eight patients with ischaemic heart failure received nifedipine. Four patients served as controls. Nifedipine reduced mean arterial pressure and systemic vascular resistance in every patient. There were no significant changes in the relative blood volumes of the intestinal, hepatic, or splenic regions or in hepatic venous wedge pressure (reflecting portal venous pressure), suggesting unchanged splanchnic vascular pressure-volume relationship. Nifedipine caused a 6.3 +/- 1.0% increase in relative pulmonary blood volume and a slight increase in pulmonary vascular distending pressure from 16.1 +/- 2.9 mmHg to 17.5 +/- 2.8 mmHg (P < 0.05), suggesting that the increase in pulmonary blood volume was passively mediated. In conclusion, nifedipine did not change splanchnic vascular capacitance, but caused a small increase in pulmonary blood volume, which probably was a passive response to increased distending pressure.

Adult↗
PubMed1992

Nitroprusside and regional vascular capacitance in patients with severe congestive heart failure.

BACKGROUND: This study investigates the effects of sodium nitroprusside on regional vascular capacitance in eight patients with severe congestive heart failure (New York Heart Association class IV) and pulmonary hypertension. METHODS AND RESULTS: Regional relative blood volumes in the splanchnic and pulmonary region were determined by equilibrium blood pool scintigraphy. Hepatic venous wedge pressure and the mean of pulmonary artery and pulmonary capillary wedge pressure were used to represent the distending pressures of the splanchnic and pulmonary capacitance vessels, respectively. The dose of sodium nitroprusside was increased stepwise until systolic pulmonary artery pressure decreased below 50 mm Hg. This caused reductions in mean aortic pressure from 89 +/- 5 to 66 +/- 3 mm Hg (p less than 0.005), in pulmonary capillary wedge pressure from 31 +/- 1 to 16 +/- 2 mm Hg (p less than 0.001), and in hepatic venous wedge pressure from 10.0 +/- 1.0 to 5.9 +/- 0.6 mm Hg (p less than 0.005). Intestinal blood volume increased by 26 +/- 7% (p less than 0.005), whereas hepatic blood volume decreased by 9 +/- 3% (p less than 0.02). Pulmonary blood volume was unchanged. Analysis of intestinal and pulmonary vascular pressure-volume relations showed larger or equal blood volumes contained at lower distending pressures, indicating that sodium nitroprusside reduced smooth muscle tone of the capacitance vessels in these regions. The reduction of hepatic blood volume was compatible with passive expulsion of blood subsequent to reduced venous pressure. There was no change in the count rate from the spleen. CONCLUSIONS: Nitroprusside reduced venous pressure in patients with congestive heart failure by active relaxation of intestinal and pulmonary capacitance vessels. Hepatic vascular volume was probably reduced by a passive mechanism.

Gated Blood-Pool Imaging↗
PubMed1991

[Shunt quantification in adults with atrial septal defects using the radionuclide technique].

Quantification of left to right shunt was carried out in 15 adult patients, mean age 49 years, with a suspected ostium secundum atrial septal defect (ASD II). Radionuclide shunt quantitation correlated well with the results of right heart catheterization (r = 0.85). The radionuclide technique failed in two patients for technical reasons, but revealed no false negative or false positive results when technically satisfactory. The diagnosis was confirmed at operation. It is concluded that the radionuclide technique is a useful and reliable method which can also be used at follow-up after surgery in patients with atrial septal defects of secundum type.

Adult↗
PubMed1987

Physical training and occupational rehabilitation after aortic valve replacement.

Forty-four patients were tested 2, 6 and 12 months after an isolated aortic valve implantation in order to evaluate the influence of training and vocational assistance on physical work capacity and the rate of reemployment. They were randomly allocated to a training group (A) or a control group (B). Training was carried out from the eighth to the twelfth week after operation and the socio-occupational status was evaluated. Training increased physical work capacity, expressed as cumulated work (CW), by 58 per cent (P less than 0.001), decreased the rate-pressure product (RPP) by 13 per cent (P less than 0.001) and the rate of perceived exertion (RPE) by 13 per cent (P less than 0.001) at the highest comparable work load. The CW was 38 per cent higher in the training than the control group after 6 (P less than 0.02) and 37 per cent after 12 months (P less than 0.025). After one year 81 per cent in group A and 65 per cent in group B were working (NS). Reemployment correlated significantly with the CW and inversely with the duration of sick leave prior to operation. Thus, physical training shortly after aortic valve operation rapidly and persistently improves physical work capacity while return to work is less influenced by training and socio vocational assistance.

Adult↗
PubMed1986

The immediate haemodynamic and electrophysiological response to prenalterol during fixed rate pacing in patients with chronic ischaemic heart disease.

The immediate haemodynamic and electrophysiologic effects of intravenous prenalterol 2.5-75 micrograms/kg in patients with coronary heart disease without clinical heart failure were investigated during fixed rate atrial pacing. Right ventricular peak dP/dt increased pronounced and serum concentration dependent after prenalterol concomitant with an increase in stroke volume and a moderate decrease in peripheral vascular resistance. The effects on haemodynamics after prenalterol were thus serum concentration dependent but with marked interindividual variation. AV nodal conduction velocity increased significantly. It is concluded that prenalterol possess pronounced inotropic properties. The haemodynamic response to prenalterol intravenously is to a lesser degree dependent on the chronotropic effects of the drug and it is often unpredictable.

Aged↗
PubMed1984

Effect of intravenous digitoxin on inotropy, haemodynamics and P-Q interval in ischaemic heart disease.

The haemodynamic and electrophysiologic responses to rapid intravenous injection of digitoxin (0.6 mg over 5 min) were measured in 6 patients with chronic coronary heart disease without clinical heart failure. Two minutes after end of injection peripheral resistance increased and stroke volume fell, while peak dP/dt in the right ventricle showed minimal increase. AV nodal conduction velocity decreased markedly. Thereafter, the peripheral resistance remained unchanged, stroke volume and peak dP/dt in the right ventricle increased slightly, while AV conduction remained stable. In 2 control patients stable values were found during 60 min. We conclude that digitoxin given intravenously as a single bolus injection induces an abrupt slight increase in peripheral resistance. Thereafter, a gradual increase in inotropy is found. The effect on the AV node appears rapidly and remains stable.

Aged↗
PubMed1983

Hemodynamic response and valve performance during graded physical exercise in patients with Medtronic-Hall aortic valve prosthesis.

The Medtronic-Hall aortic valve prosthesis has been studied in order to evaluate its efficacy to respond to moderate (50 Watts) and heavy (100 Watts) physical exercise. A marked increase in cardiac index from 2.86 +/- 0.45 l/min/m2 BSA at rest to 6.80 +/- 0.51 l/min/m2 BSA at the heaviest work load was well-tolerated. Peak pressure gradient rose from 7.9 +/- 8.7 mmHg at rest to 23.0 +/- 16.3 mmHg during the heaviest physical exercise. Utilization of the available valve orifice area was acceptably good. The discharge coefficient, which is the ratio between the effective orifice area and the internal stent orifice area, was 0.69 +/- 0.17 at rest. The performance index, which is the ratio between the effective orifice area and the annulus area, was 0.44 +/- 0.11 at rest. Both indices tended to increase during maximal exercise, possibly due to a more favorable position of the valve in relation to flow pattern.

Adult↗
PubMed1982

Haemodynamic effects of nifedipine and propranolol in patients with hypertrophic obstructive cardiomyopathy.

The haemodynamic effects of nifedipine, propranolol, and the combined administration of the two drugs were studied in 12 patients with hypertrophic obstructive cardiomyopathy. The combined administration of nifedipine and propranolol appeared to be superior to that of nifedipine alone. The spontaneous heart rate was reduced in most cases after nifedipine plus propranolol, and at atrial pacing the following results were obtained: left ventricular peak systolic pressure was reduced from 200 +/- 39 to 157 +/- 30 mmHg; a positive correlation was found between the pre-drug left ventricular end-diastolic pressure and the magnitude of reduction in left ventricular end-diastolic pressure; systolic blood pressure was reduced from 125 +/- 31 to 111 +/- 27 mmHg, and total peripheral resistance was reduced from 1403 +/- 307 to 1160 +/- 209 dyne s-1 cm-5. The combined administration reduced the resting left ventricular outflow gradient from 76 +/- 19 to 45 +/- 26 mmHg, while cardiac index was left unchanged. The effects on mean pulmonary arteriolar resistance and mean pulmonary arteriolar resistance and mean pulmonary capillary venous pressure were in most cases slight and insignificant. The results indicate an improved haemodynamic condition in patients with hypertrophic obstructive cardiomyopathy after the combined administration of nifedipine and propranolol: a treatment that might provide a new and useful alternative to already existing medication.

Adult↗