Search PubMed⌕ Search

Biomedical subjects

J N Cohn

Publications and source records attributed to J N Cohn.

At least 361 records · Page 20Linked to original sources
PubMed1977

Aortic regurgitation associated with ventricular septal defect. Echocardiographic and hemodynamic observations.

Ventricular septal defect is sometimes associated with aortic regurgitation. In this report, an echocardiogram demonstrating dramatic prolapse of the noncoronary cusp into the left ventricular outflow tract and ventricular septal defect in a patient with Down's syndrome and ventricular septal defect, confirmed by angiographic studies, is presented. The echocardiogram supports the concept of anatomic lack of support of the aortic ring due to a deficient septum and hemodynamically significant flow of blood to the right ventricle through the ventricular septal defect, resulting in trauma to aortic cusps and prolapse.

Adult↗
PubMed1977

Hemodynamic improvement after oral hydralazine in left ventricular failure: a comparison with nitroprusside infusion in 16 patients.

Hydralazine was administered in a single oral dose of 50 to 100 mg in 16 patients with left ventricular failure due to cardiomyopathy. It produced sustained effects for at least 4 h characterized by a significant increase in cardiac output, a reduction in arterial and pulmonary arterial pressure, and a slight rise in heart rate. When compared to nitroprusside infusion in these same patients, hydralazine produced a similar reduction in systemic vascular resistance but a slightly greater increase in cardiac index (0.74 versus 0.95 litres/min-m2), with a lesser fall in mean arterial pressure (7.8 versus 13.6 mm Hg, P less than 0.01), mean pulmonary arterial pressure (4.2 versus 11.3 mm Hg, P less than 0.001), and pulmonary wedge pressure (5.5 versus 9.9 mm Hg, P less than 0.001). Forearm venous tone decreased and venous compliance increased during nitroprusside infusion, but they were unchanged after hydralazine therapy. These data suggest that hydralazine may be a useful agent in the treatment of chronic left ventricular failure.

Administration, Oral↗
PubMed1977

Defective calcium transport by cardiac sarcoplasmic reticulum in spontaneously hypertensive rats.

Ca2+ uptake and binding and Ca2+-ATPase activity of cardiac sarcoplasmic reticulum (SR) from spontaneously hypertensive rats (SHR) were compared to that obtained from normotensive Wistar-Kyoto (WKY) rats. Ca2+ uptake (172 +/- 3.7 nmol/mg of protein per min in WKY vs. 112 +/- 2.6 in the SHR, P less than 0.001) and binding (154 +/- 3.0 nmol/mg per min in WKY vs. 101 +/- 1.8 in the SHR, P less than 0.01) were decreased in the SHR. Ca2+-ATPase activity, however, was significantly higher in the SHR (118 +/- 3.1 nmol of P per mg of protein per min vs. 86 +/- 1.1 in the WKY, P less than 0.001), suggesting "uncoupling" of the ATPase to calcium transport. Cyclic AMP-dependent phosphorylation of SR was significantly decreased in SHR (0.71 +/- 0.05 vs 0.32 +/- 0.07 nmol of P/mg of protein per 10 min, P less than 0.001) and there was an excellent correlation between cyclic AMP-induced phosphorylation of SR and Ca2+ uptake (r = 0.81). Differences in both cyclic AMP-dependent phosphorylation and Ca2+ uptake between the two groups were evident at 10 weeks and increased progressively to 22 weeks of age. Differences in endogenous cyclic AMP-dependent protein kinase activity may partly explain the decreased Ca2+ transport in SHR.

Adenosine Triphosphatases↗
PubMed1976

Ventricular dimensions measured noninvasively by echocardiography in the awake dog.

A surface echocardiographic technique was employed in 37 mongrel dogs for measurement of left ventricular dimensions. Intracardiac bolus injections of dextran were used as an echo contrast material to visualize cardiac chambers, and the identification of intracardiac structures was further confirmed by postmortem examination. The left ventricle could be satisfactorily visualized from both the right and left chest, providing two transverse left ventricular diameters nearly perpendicular to each other. End-diastolic and end-systolic diameter measurements in the two separate transverse planes differed by an average of only 0.07 and 0.1 cm, respectively, and dimensional measurements were reproducible from day to day. Diastolic diameter ranged from 3.0 to 4.7 cm (mean 3.7 cm) and systolic diameter 1.9 to 3.3 cm (mean 2.6 cm). Diameter was directly related to animal weight. Stroke volume calculated from the dimension measurements correlated with stroke volume calculated from indicator-dilution curves in 16 dogs. Ejection fraction averaged 0.67 and 0.54, depending on the formula used to calculate volumes. These results indicate that surface echocardiography can be employed to evaluate left ventricular dimensions in the awake dog.

Animals↗
PubMed1976

Bradycardia with mitral valve prolapse: a potential mechanism of sudden death.

Eleven members of a family with a high prevalence of mitral valve prolapse were investigated. Seven had documented sinus bradycardia, and five had mitral valve prolapse. Three patients with both mitral valve prolapse and bradycardia had recurrent syncope reproduced by simple head-up tilting, and in one patient this resulted in asystole. The hemodynamic response to isoproterenol and phenylephrine administration were normal. Supine plasma norepinephrine levels were normal in all three and increased appropriately in two of three patients after tilting. Atrial pacing studies documented marked prolongation of atrial-His intervals and inability to maintain 1:1 atrioventricular conduction when paced at a rate of 120/min. These findings were reversed by atropine. This family shows a close correlation between mitral valve prolapse and potentially lethal bradycardia. Excessive vagal tone is believed to be responsible for both bradycardia and sinus arrest, which in two patients was prevented by permanent demand pacing.

Adolescent↗
PubMed1976

Splanchnic hemodynamics in cirrhotic patients with esophageal varices and gastrointestinal bleeding.

Twenty cirrhotic patients with esophageal varices and an episode of gastrointestinal bleeding within the previous week underwent hemodynamic studies which used an indicator dilution technique based on selective catheterization of the splanchnic arteries and hepatic vein. Portasystemic shunting of splenic arterial flow averaged 95% (range 80 to 100%) in 17 patients with proved variceal bleeding, but only 8% in 3 who bled from another site. Superior mesenteric shunting averaged 70% (range 27 to 100%) in those who bled from varices, and no shunting was detectable in the nonvariceal bleeders. In at least 4 patients shunting was essentially complete from both beds. In 11 others, however, more than one-third of mesenteric flow still perfused the liver. The pressure gradient from the wedge to free position in the hepatic vein and the hepatic blood flow bore no relationship to the degree of shunting. These data indicated the variability of the splanchnic hemodynamic pattern that may exist in alcoholic patients with esophageal varices. If hemodynamic factors are important in determining the response to surgery, indicator dilution studies to quantitate portasystemic shunting may be a vital part of preoperative evaluation.

Abdomen↗
PubMed1975

Hemodynamic effect of dobutamine in patients with severe heart failure.

Dobutamine, a derivative of dopamine, was infused at a rate of 10 mug/kg per min in 15 patients with severe congestive heart failure. Cardiac output increased from an average of 3.1 to 5.6 liters/min (P less than 0.001) with no change in mean arterial pressure (93.3 to 98.2 mm Hg) and only a slight increase in heart rate (98.5 to 105.2 beats/min) (P less than 0.02). Pulmonary wedge pressure was decreased from an average of 27.4 to 21.1 mm Hg (P less than 0.001). In seven patients a dose of 5 mug/kg per min also produced a significant increase in cardiac output but the effect was less than with the 10 mug/kg per min dose. No side effects were observed during the infusion. Dobutamine therefore is a potent inotropic drug with limited chronotropic and peripheral vascular effects and deserves therapeutic trial in the short-term management of low output heart failure.

Adult↗
PubMed1975

Sequential changes in intrarenal hemodynamics during saline infusion in the dog.

Intrarenal blood flow and volume (indicator-dilution technique), kidney volume (mercury-in-rubber resistance gage), intr-renal venous pressure, filtration fraction, and sodium excretion were determined dequentially before and during a l-h infusion of isotonicsaline 80 ml/kg in anesthetized dogs. The cortical fraction of renal blood flow roseduring the first 20 min of infusion from an average of 70 to 77%, butreturned nearly to control levels during the last 20 min of infusion because ofa low rise in noncortical flow. During the first 20 min a 23% increase in cortical blood volume accounted for one-third of the 8.5% increase in kidney volume, whereasin the last 20 min cortical blood volume had fallen nearly to control values and kidneyvolume was increased by 17.2%. Intrarenal resistances calculated from intrarenalpressure and flow indicated persistent cortical prevenous dilatation, progressive cortical venous constriction, and only a slight late reduction in noncortical resistance. These data indicate that hemodynamics are shanging continuously during saline infusion and the natriuresis probably is multifactorial.

Animals↗
PubMed1975

Comparative hemodynamic effects of chewable isosorbide dinitrate and nitroglycerin in patients with congestive heart failure.

Vasodilators are known to be effective in improving the hemodynamics of congestive heart failure by increasing cardiac output and reducing left ventricular filling pressure (LVFP). Long acting agents are needed to augment the practicality and availability of chronic vasodilator therapy. In the present study the vascular effects of chewable isosorbide dinitrate (CHIS), sublingual nitroglycerin (NTG) and placebo (P) were compared in eight patients with high LVFP due to heart failure. Patients with LVFP (pulmonary wedge pressure) over 14 mm Hg were given CHIS, 10 mg, NTG, 0.6 mg, and P, two chewable tablets, in random fashion. Heart rate (HR), blood pressure (BP) and LVFP were monitored for three hours after each drug. HR was not significantly affected by any drug, although it rose slightly after NTG and fell after CHIS. Significant reduction of BP occurred only after NTG, with peak effect at five minutes, but lasting only 15 minutes. NTG reduced LVFP 5.1 mm Hg (19.5%, P, less than 0.05), at peak effect, but LVFP was no longer significantly lower by 20 minutes after NTG. After CHIS, LVFP fell significantly within five minutes, reached a peak reduction of 8.6 mm Hg (32;7%, P less than 0.01) at 15 minutes, and remained significantly lower through three hours. Thus CHIS provides a nitrate action of rapid onset and sustained effect that may be useful for chronic vasodilator therapy of heart failure.

Administration, Oral↗
PubMed1974

Hypertension--1974.

Explore the source record for details and available documents.

Antihypertensive Agents↗