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Biomedical subjects

C J Carlson

Publications and source records attributed to C J Carlson.

28 records · Page 2Linked to original sources
PubMed1980

A new method for quantification of aortic regurgitation during cardiac catheterization.

Clinical methods of estimating aortic insufficiency are unsatisfactory. We developed a radioisotope method of quantitating aortic regurgitant volume. The method is easily performed, convenient, and can be carried out repetitively. The mathematical derivation of the method is presented and a mechanical model is used to verify assumptions. The potential utility and possible difficulties of applying the method clinically are discussed.

Aortic Valve Insufficiency↗
PubMed1980

Renal effects of nitroprusside and hydralazine in patients with congestive heart failure.

The acute effects of nitroprusside infusion and intravenous hydralazine on renal hemodynamics and function were evaluated in nine male patients with severe, low cardiac output, congestive heart failure (CHF). Both drugs resulted in marked systemic hemodynamic improvement. Nitroprusside had a more profound effect on pulmonary artery pressure, while hydralazine produced a greater elevation in cardiac output. Significant decreases in both systemic and pulmonary vascular resistance and pulmonary capillary wedge pressure with increases in stroke volume and stroke work index were noted with both drugs. Total renal resistance decreased and renal blood flow (RBF) significantly increased with both drugs, while the distribution of cardiac output to the kidney remained depressed. Glomerular filtration rate (GFR) did not change significantly with either drug, although increases in GFR were seen in selected patients in whom RBF increased by more than 10% from control. The fraction of plasma filtered decreased toward normal with both drugs and excretion of total cations was significantly increased. These changes all represent improvements in systemic and renal hemodynamic abnormalities occurring in patients with CHF; their maintenance during long-term therapy would facilitate patient management.

Adult↗
PubMed1980

Continuous positive-pressure ventilation decreases right and left ventricular end-diastolic volumes in the dog.

We investigated the mechanism(s) responsible for the decreased cardiac output during continuous positive-pressure ventilation (CPPV). Seven dogs were anesthetized with chloralose-urethane, intubated, and ventilated using a volume ventilator. We measured heart rate, stroke volume, and the determinants of stroke volume: left and right ventricular end-diastolic volumes, isovolumic and ejection phase indices of myocardial contractility, and pulmonary and systemic arterial pressures. Myocardial blood flow was estimated using radioactive microspheres. Variables were measured during a control period of intermittent positive-pressure ventilation (IPPV), 8-20 minutes after the initiation of CPPV using 12 cm H2O positive end-expiratory pressure (PEEP), and 8-20 minutes after the removal of PEEP. CPPV decreased cardiac output but did not affect total or regional myocardial blood flow or the ratio of subendocardial to subepicardial blood flow. Isovolumic and ejection phase indices of myocardial cointractility, heart rate, and systemic arterial pressure did not change during CPPV. Right and left ventricular end-diastolic and end-systolic volumes decreased markedly during CPPV. We conclude that CPPV decreases cardiac output in accordance with Starling's law by decreasing preload.

Animals↗
PubMed1979

Rate of progression of severity of valvular aortic stenosis in the adult.

In a retrospective study, 29 patients at least 20 years of age with known aortic stenosis are reported who had the peak systolic gradient (PSG) measured on at least two occasions without an intervening surgical procedure or episode of endocarditis. In these 29 patients, there were 31 intervals available for evaluation with a mean follow-up time of 43.5 months (1 week to 120 months). In 16 of the 31 intervals, the PSG increased by 50% or more and in 15, it did not. In the group where the PSG increased, the average rate of increase was 1.3 mm. Hg/month with the most rapid gradient increase at 3.8 mm. Hg/month. Progression to high gradient was correlated with the development of angina pectoris or left ventricular hypertrophy by voltage and ST-T wave changes. In this study, other symptoms were not helpful in predicting an increase in severity. It is still recommended, however, that any patient with aortic stenosis and the development of symptoms of congestive heart failure or exertional syncope should be suspected of having progressed to severe aortic stenosis and should be restudied.

Adult↗
PubMed1978

Creatine phosphokinase MB isoenzyme in hypothermia: case reports and experimental studies.

Six patients with severe medical disorders and profound hypothermia are presented who had elevated total serum creatine phosphokinase (CPK) and CPK-MB isoenzyme activity without clinical or postmortem evidence of acute myocardial infarction. Experiments in dogs indicate that hypothermia reduces total CPK activity in both striated and myocardial muscle resulting in increased serum enzyme activity. These data suggest that profound hypothermia may result in diffuse striated and cardiac muscle cellular injury without evidence of discrete infarction with consequent release of CPK-MB isoenzyme into serum.

Adult↗
PubMed1977

Improved signal processor for the ultrasonic dimension gauge.

Inexpensive modifications and additions to improve the performance of a widely used ultrasonic dimension gauge are presented in detail. These include a pulse width demodulator, averaging peak detector, and improved signal processing circuits. Benefits of the modifications are improved frequency response (to 1 kHz), lowered drift, increased sensitivity (to 128 mV/mm), rational gain calibration, calibrated zero suppression, and improved recovery from signal dropout. The modifications result in the ability to take the derivatives of ventricular wall motion with greater reliability.

Echocardiography↗
PubMed1977

Mitral regurgitation due to intermittent prosthetic valvular dysfunction.

A second case of malfunction of a Harken disk valve due to undue disk wear is reported. Two and one-half years after aortic and mitral valvular replacement, the patient had paraprosthetic aortic insufficiency and physical findings suggesting intermittent dysfunction of his prosthetic mitral valve. Catheterization showed intermittent hemodynamic abnormalities; fluoroscopic and cineangiographic findings indicated intermittent mitral regurgitation secondary to undue mitral disk wear. At operation, the excised valve showed normal struts and sewing ring but severe disk wear. There was loss of disk substance and rim notching.

Cardiac Catheterization↗
PubMed1976

Mitral valve area in combined mitral stenosis and regurgitation.

Eight patients with mixed mitral stenosis and regurgitation underwent hemodynamic and angiographic study prior to mitral valve replacement. The stenotic orifice of the mitral valve was calculated employing the total left ventricular stroke volume by cineangiography as the numerator of the Gorlin Formula. Excellent agreement with the measured orifice of the mitral valve was obtained using a value of 37.9 (0.85 X 44.5) for the constant in the Gorlin formula as recommended by Cohen and Gorlin. Recalculation of this constant independently by our data yielded a value that was almost identical. Regurgitant flows and orifice sizes were calculated for each patient using the same constant as for calculation of the stenotic orifices.

Angiocardiography↗