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Biomedical subjects

W H Barry

Publications and source records attributed to W H Barry.

At least 127 records · Page 7Linked to original sources
PubMed1981

Myocardial salvage after intracoronary thrombolysis with streptokinase in acute myocardial infarction.

Nine patients with acute myocardial infarction had cardiac catheterization and intracoronary infusions of streptokinase 2.3 to 4.3 hours (mean, 3.5) after the onset of symptoms. Occluded coronary arteries were opened within approximately 20 minutes in all patients, but reocclusion occurred in one patient. The immediate effect of thrombolysis on myocardial salvage was assessed with the intracoronary injection of thallium-201. Improved regional perfusion, indicating myocardial salvage after recanalization, was observed in seven of the nine patients. One patient, who had also sustained a nontransmural infarction one week before, had no change after thrombolysis. In the ninth patient, recanalization of a coronary artery was followed by reocclusion and worsening of the myocardial-perfusion defect. Intracoronary thallium-201 studies two weeks and three months after streptokinase infusion in two patients were unchanged in comparison with scintiscans performed 1.5 hours after thrombolysis. These short-term observations suggest that recanalization of obstructed coronary arteries after intracoronary thrombolysis can salvage jeopardized myocardium, However, evaluation of the long-term effects of this procedure on survival and myocardial function will require controlled clinical trials.

Aged↗
PubMed1981

Prognostic importance of anginal symptoms in angiographically defined coronary artery disease.

To evaluate the prognostic importance of anginal symptoms, 44 patients with angiographically defined coronary artery disease and no anginal symptoms at time of cardiac catheterization were selected from the Duke Harvard Collaborative Data Bank. They were "matched" with 127 symptomatic patients in the Data Bank who had similar coronary anatomy and ventricular function. Follow-up data indicated that the patients without anginal symptoms had a significantly better prognosis over a 7 year period than did those with symptoms: Annual mortality in the asymptomatic group was 2.7 percent compared with 5.4 percent in the group with angina (P 0.05). Although the patient population was a highly selective one and the matching categories were relatively broad, these results suggest that the presence of anginal symptoms may be an important independent correlate of prognosis in patients with coronary artery disease. The absence of angina did not preclude the presence of multivessel disease and did not necessarily imply a benign prognosis, because the yearly mortality rate was nearly 5 percent in the subgroup of asymptomatic patients with three vessel disease.

Angina Pectoris↗
PubMed1981

Changes in cellular Na+, K+, and Ca2+ contents, monovalent cation transport rate, and contractile state during washout of cardiac glycosides from cultured chick heart cells.

To delineate more clearly the importance of altered monovalent cation transport rate in the mediation of the positive inotropic effects of cardiac glycosides, we studied changes in the contractile state and rate of uptake of K+ and Rb+ by monolayer cultures of chick embryo ventricular cells during exposure to and washout of ouabain and dihydro-ouabain. These cardiac glycosides produced a positive inotropic effect in this system, accompanied by a significant reduction in monovalent cation transport rate, by increases in cellular contents of Na+ and Ca2+, and by a decrease in cellular content of K+ as judged by radioisotopic tracer studies. Following removal of glycosides from media bathing the cultures, monovalent cation transport rate returned to normal within 1 minute, followed by a loss of inotropy which was complete by 7 minutes, a time at which cellular [Ca2+] had returned to normal. The bulk cellular concentration of Na+ remained increased, however, and that of K+ depressed for longer periods. Veratrine (1 microgram/ml) induced a positive inotropic effect, but caused a less marked increase in cellular [Na+] than did equipotent concentrations of ouabain and dihydroouabain. These results indicate that there is not a simple relationship between bulk cellular [Na+] and magnitude of inotropic effect in these cells, and are consistent with the proposal that there is a subsarcolemmal space in which [Na+] regulates Ca2+ fluxes and contractility, and in which [Na+] is regulated primarily by the balance between transsarcolemmal influx and Na+ pump rate and, to a lesser degree, by bulk [Na+].

Animals↗
PubMed1981

Differing sensitivities of Purkinje fibers and myocardium to inhibition of monovalent cation transport by digitalis.

The extent of inhibition of monovalent cation active transport in Purkinje fibers and myocardium in response to toxic and inotropic doses of digitalis were studied in the dog to elucidate the factors underlying the different relative sensitivities of these tissues to the toxic arrhythmogenic effects of digitalis. Monovalent cation transport inhibition was assessed by measuring uptake of the K(+) analog Rb(+) in samples of myocardium and Purkinje fibers after in vitro ouabain exposure and after acute or chronic administration of digoxin in vivo. The active uptake of Rb+ was determined as the difference between total uptake and uptake in the presence of 1.0 mM ouabain. Mean active uptake of Rb(+) by Purkinje fibers from control hearts was 1.62+/-0.11 (SEM) nmol/mg wet wt per 15 min, significantly greater than the value of 0.49+/-0.05 for myocardium (P < 0.001). Concentration-effect curves for inhibition of monovalent cation active transport by in vitro exposure to graded concentrations of ouabain showed that the concentration for half-maximal inhibition of monovalent cation transport, IC(50), for Purkinje fiber transport was 0.4 muM, significantly less than the value of 1.4 muM for myocardial samples. Dogs were given toxic doses of digoxin (0.3 mg/kg i.v.). At onset of sustained ventricular tachycardia, they were killed and monovalent cation transport measured in myocardial and Purkinje fiber samples. Active Rb(+) uptake was inhibited by 44% in myocardial samples, whereas a significantly greater inhibition of 76% was noted in Purkinje fibers (P < 0.01). Similar data were obtained for both transmural myocardial biopsy samples and subendocardial trabecular samples obtained from regions adjacent to Purkinje fibers. Another group of dogs received a nontoxic dose of 0.02 mg/kg i.v. daily for 6 d. Myocardium showed a 17% reduction in Rb(+) active uptake compared to control animals receiving no drug, whereas Purkinje fiber transport was reduced in these dogs to a significantly greater extent averaging 44% (P < 0.001). Thus, both toxic and inotropic (non-toxic) doses of digoxin inhibited monovalent cation transport in Purkinje fibers to a greater extent than in myocardium. This difference in apparent sensitivity of monovalent cation transport to digoxin may contribute to the previously reported tendency of digitalis toxic arrhythmias to arise in Purkinje fibers.

Animals↗
PubMed1981

Impact of a cardiology data bank on physicians' prognostic estimates. Evidence that cardiology fellows change their estimates to become as accurate as the faculty.

To determine whether physicians would be influenced by the prognostic information in a large coronary artery disease data bank, cardiology faculty and fellows made initial estimates of the prognoses of their patients and then made revised final estimates after seeing the outcome of matched patients (OMP) from the data bank. The faculty cardiologists' original estimates proved to be as accurate as those of the data bank's OMP, and the faculty revised their estimates minimally in response to the data bank's OMP. Conversely, the cardiology fellows' original estimates were less accurate than the data bank's OMP, and under all observed circumstances the fellows responded more to the data bank's OMP than did the faculty. As a result, the accuracy of the fellows' final estimates was similar to the accuracies of both the faculty cardiologists and the data bank's OMP. Computerized data banks seem more likely to have impact when their information is provided to physicians who are relatively inexperienced with the disease in question.

Cardiology↗
PubMed1980

Effects of graded hypoxia on contraction of cultured chick embryo ventricular cells.

The quantitative relationship between a given decrease in O2 tension (Po2) and the degree of depression of contractile function is difficult to define in intact myocardial tissues because of uncertainty in estimation of diffusion limitations. We therefore have studied the effects of hypoxia on contractility in a system with minimal series diffusion barriers, consisting of single cells within spontaneously contracting monolayers cultured from 10-day-old chick embryo ventricles. Reversible decreases in amplitude and velocity of cell wall motion occurred over a 3- to 4-min period when perfusate Po2 was less than 12 mmHg, and a maximum depression to about 30% of control levels occurred at Po2 values less than 4 mmHg. On reoxygenation, recovery of amplitude and velocity of contraction occurred in less than 15 s. Inhibition of glycolysis with 0.1 mM iodoacetate resulted in a more marked decrease in contraction amplitude and a significant slowing of beating rate during hypoxia. In addition, the critical Po2 at which contractile function became impaired was increased to about 16 mmHg. Thus, high-energy phosphates derived from anaerobic glycolysis appear to be able to support a reduced level of contractility during brief periods of hypoxia in these cultured heart cells.

Animals↗
PubMed1980

Diastolic pressure-volume relations in the diseased heart.

Alterations in ventricular diastolic properties are commonly seen in the diseased heart, and have been extensively studied in coronary artery disease, congestive cardiomyopathy, and left ventricular hypertrophy due to pressure or volume overload. Acute increases in left ventricular (LV) diastolic pressure relative to volume occur regularly during the transient ischemia of angina pectoris and may contribute to the dyspnea and pulmonary congestion that commonly accompany this condition. Although the mechanism of this altered disastolic distensibility is debated, a substantial body of evidence favors a role for residual diastolic interaction between contractile elements in the ischemic heart. Congestive cardiomyopathy also appears to be associated with increased LV diastolic stiffness. While this may in part be related to fibrosis of the LV wall, shifts of the abnormal diastolic pressure-volume relation toward normal have been reported with sodium nitroprusside infusion or the beta-adrenergic agonist salbutamol, suggesting important contribution of physiologic factors to the increased resting LV stiffness in this condition. LV hypertrophy (LVH) is associated with increased effective diastolic chamber stiffness, but normalized LV diastolic stiffness is increased only in LVH due to chronic pressure overload. Possible explanations for these findings are discussed.

Adenosine Triphosphate↗
PubMed1979

Left heart catheterization and angiography via the percutaneous femoral approach using an arterial sheath.

An arterial sheath with a proximal hemostasis valve and a side-arm extension tube was used in 562 consecutive patients undergoing cardiac catheterization and angiography via the femoral approach. Serious complications were rare. There was one death, one peripheral embolism, and one episode of delayed groin hemorrhage. The incidence of minor complications, including hematoma formation, in this series compares favorably with our own and the reported experience of others using the conventional percutaneous femoral approach. The sheath technique facilitated catheter exchanges and reduced patient discomfort. In addition, femoral artery pressure could be monitored via the side arm of the sheath during the catheterization. This proved helpful during retrograde catheterization of patients with aortic stenosis, as well as in detection of damping of coronary artery catheter tip pressure during coronary arteriography and hypotension following left ventriculography. Based upon this experience, use of an arterial sheath has become our standard practice when left heart catheterization is performed via the femoral approach, and the use of several different catheters is anticipated.

Aged↗
PubMed1979

Traumatic pulmonary artery--left atrial fistula: an unusual case of cyanosis in an adult.

Eighteen months after sustaining a stab wound to the left upper chest, a 59-year-old man presented with cyanosis and extertional dyspnea. Arterial desaturation due to a central 22 per cent right-to-left shunt was present. A selective pulmonary arteriogram demonstrated a fistula between the main pulmonary artery and the left atrium. At operation the fistula was closed. A laceration of the pulmonic valve and healed pericarditis were present. Marked symptomatic improvement followed the operation, but a murmur of pulmonic valvular regurgitation persisted. The fistula and laceration of the pulmonic valve were probably traumatic in origin.

Cyanosis↗
PubMed1979

Myocardial contractile function in aortic stenosis as determined from the rate of stress development during isovolumic systole.

To assess myocardial contractile function in the chronically hypertrophied human left ventricle, the rate of stress development (dsigma/dt) as a function of developed stress (sigmaD) during isovolumic systole was examined. Results for eight patients with aortic stenosis were compared with those for seven subjects with normal left ventricular function and with those for five patients with idiopathic congestive cardiomyopathy. The rate of stress development (dsigma/dt) was nearly identical in patients with aortic stenosis and in normal subjects over a wide range of values of sigmaD but was significantly lower in patients with cardiomyopathy (P less than 0.01 versus control subjects and patients with aortic stenosis). Normal values for dsigma/dt held not only for patients with compensated pressure overload, but also for those patients with aortic stenosis with depressed left ventricular ejection fraction and overt congestive failure. Similar findings were obtained when the first derivative of left ventricular pressure (dP/dt) was examined as a function of developed left ventricular pressure in normal subjects and patients with aortic stenosis or cardiomyopathy. These results indicate that contractile function as characterized by the isovolumic rate of stress development is not necessarily impaired in chronic pressure overload hypertrophy.

Adult↗
PubMed1979

Inotropic effects and changes in sodium and calcium contents associated with inhibition of monovalent cation active transport by ouabain in cultured myocardial cells.

Cultured monolayers of spontaneously contracting chick embryo ventricular cells were perfused with culture medium containing ouabain. Contractile state was monitored by an optical-video system recording amplitude and velocity of cell wall motion. Positive inotropic effects of 2.5 x 10(-7) to 10(-6) M ouabain were manifest within 1.5-2 min, and reached a stable plateau within 5-6 min. The inotropic effect was fully reversed within 5 min after washout of ouabain. Inhibition of uptake of 42K+ (or the K+ analog 86Rb+) and efflux of 24Na+ occurred 1.5-2 min after exposure to ouabain. The degree of inhibition of transport was closely related to the magnitude of the positive inotropic effect throughout the ouabain concentration range 10(-7) to 10(-6) M. After washout of ouabain from monolayers, the monovalent cation active transport rate returned to normal within 1 min. Thus, both the onset and offset of inotropic action of ouabain were closely related temporally to inhibition of the sodium pump. Exposure to ouabain caused significant increases in exchangeable Na and Ca contents that appeared to be developed within 5 min. These data support the hypothesis that inhibition of monovalent cation active transport by ouabain is causally related to the development of positive inotropy and are consistent with modulation of Ca content by intracellular Na+ via the Na+-Ca2+ exchange carrier mechanism.

Animals↗
PubMed1979

Isolated single coronary artery: diagnosis, angiographic classification, and clinical significance.

Isolated single coronary artery is a rare congenital anomaly occuring in approximately 0.024% of the population. This entity can be diagnosed during life only by coronary angiography. Ten patients with isolated single coronary artery are reported. Based on angiographic analysis, a new classification is proposed, according to the site of origin and anatomical distribution of the branches. Typical angina did not occur with single coronary artery in the absence of coexisting coronary artery disease or aortic stenosis. No correlation was apparent between the type of anomalous patterns and the symptoms of angina.

Adult↗
PubMed1977

Measurement of the human magnetic heart vector.

A unipositional lead system has been developed to record the human magnetic heart vector and to permit comparison with the electric heart vector recorded with a conventional Frank lead system. Recordings made in five normal subjects showed a remarkably consistent relation between the electric and magnetic heart vectors. However, the angle between electric heart vector R and T waves was markedly different from the magnetic heart vector R-T angle. In addition, recordings made in two patients with bundle branch block showed a different relation between the electric and magnetic heart vectors compared to normal subjects. These data support the hypothesis that magnetic measurements have a different sensitivity to some components of cardiac activation compared with body surface potential measurements.

Electrocardiography↗