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Biomedical subjects

C V Leier

Publications and source records attributed to C V Leier.

At least 163 records · Page 9Linked to original sources
PubMed1982

Vasodilators and prostaglandin inhibitors in primary pulmonary hypertension.

Ten women with primary pulmonary hypertension had resting hemodynamic measurements taken before and after the nonparenteral administration of various vasodilators and prostaglandin inhibitors. Only sublingual isoproterenol, alone or combined with sublingual isosorbide dinitrate, effected a substantial (greater than 20%) drop in pulmonary vascular resistance; this decrease was accompanied by little change in pulmonary artery pressure. Isosorbide dinitrate was the only drug that elicited any reduction in pulmonary artery pressure; pulmonary vascular resistance decreased modestly. The oral administration of diazoxide, hydralazine, phentolamine, and tolazoline elicited little change in pulmonary artery pressure or resistance. Except for tolazoline, all these agents significantly decreased systemic blood pressure and resistance. Prostaglandin inhibition by indomethacin (acute and chronic dosing) increased pulmonary and systemic vascular resistances and reduced cardiac output. Aspirin combined with dipyridamole elicited no changes. The vasodilators and prostaglandin inhibitors studied evoked little improvement in resting pulmonary hemodynamic abnormalities in primary pulmonary hypertension.

Adolescent↗
PubMed1982

Effect of afterload on left ventricular performance in experimental animals. Comparison of the pre-ejection period and other indices of left ventricular contractility.

Afterload reduction has become a routine treatment of patients with severe heart failure. In order to investigate the effect of afterload changes on indices of left ventricular performance, seven anesthetized dogs were studied. Serial alterations of afterload were produced with sodium nitroprusside and methoxamine infusions while the heart rate was maintained constant with right atrial pacing (120/min). High fidelity left ventricular (LV) pressure, aortic pressure (AoP) and systolic time intervals (STI) were measured simultaneously as a control and each time with the AoP changes. LV max dp/dt was measured by an RC differentiation and DP/DT was calculated from the pressure pulses and systolic time intervals. Each change in AoP resulted in a significant change in isovolumic pressure (IP) and the changes were parallel. Changes in pre-ejection period (PEP) and LV max (dp/dt)/(IP) were parallel changes in IP. A significant direct relationship was found between changes in IP and PEP, and an inverse relationship existed between changes in PEP and LV max (dp/dt)/(IP). Changes in LV max dp/dt and calculated DP/DT were parallel and approached unity. Thus, afterload changes with resultant changes in IP directly alter PEP and inversely affect max (dp/dt)/(IP). These effects of pure afterload changes must be considered in clinical pharmacologic studies when LV contractility is evaluated. Furthermore, calculated DP/DT can be used to measure changes in max dp/dt because of the close relationship between these two parameters.

Animals↗
PubMed1981

Biochemical measurements of endomyocardial biopsies.

The purpose of this study is to investigate the validity of performing biochemical analyses on human endomyocardial biopsies. One problem of such analyses is the decay of metabolites between the time of biopsy and the analyses. This was addressed by varying the time delay from biopsy to submersion in liquid nitrogen (-200 degree C). Neither cyclic AMP or cyclic GMP changed significantly up to 90 seconds after biopsy. The reproducibility of the assays in human heart biopsies was determined by submitting paired samples from each procedure. The ATP content was determined by a fluorescent technique and was related to the protein and creatine content. The average ATP of 25 paired samples was 12.3 nm per mg protein; the average difference between the paired samples was -0.6, and the 95% confidence interval was 5.6 nm/mg protein. The average ATP-to-creatine ratio was 0.25; the 95% confidence interval was 0.12. The cyclic AMP and cyclic GMP were found to average 3.3 and 0.25 femtomoles/mcg protein, respectively. The 95% confidence intervals were 1.8 and 0.12 fmoles/mcg protein. The problems of sampling error and blood and connective tissue contamination decrease the reliability of the biochemical analyses. Reproducibility is adequate, however, to acquire meaningful biochemical information on the human heart.

Adenosine Triphosphate↗
PubMed1981

Biochemical and histologic correlates of ventricular end-diastolic pressure.

The associations of elevated left ventricular (LV) and right ventricular (RV) end-diastolic pressure (EDP) were evaluated in 28 patients with non-ischemic congestive cardiomyopathy. Right-sided endomyocardial biopsies from each patient were evaluated for ATP content, percent fibrosis and myocardial fiber diameter. The resting RVEDP and LVEDP and the post-angiographic LVEDP were correlated with the results from the biopsies. There was a correlation of the LVEDP with the RVEDP (r = 0.67, P less than 0.001) by a linear plot. There was no correlation of any EDP measurement with the percent fibrosis. There was, however, a rough correlation of the myocardial fiber diameter with RVEDP (r = 0.40, P less than 0.05). Myocardial ATP content correlated with the RVEDP (r = -0.53, P less than 0.005), the LVEDP (r = -0.65, P less than 0.001) and the post-angiographic LVEDP (r = -0.72, P less than 0.001). These data demonstrate that an elevated ventricular EDP correlates most closely with depressed levels of myocardial ATP. The myocardial cell diameter correlated less well and there was no correlation of EDP with fibrosis. Metabolic factors may be more important than histologic parameters in the elevated ventricular EDP of non-ischemic congestive cardiomyopathy.

Adenosine Triphosphate↗
PubMed1981

Effect of increased adrenergic activity on the relationship between electrical and mechanical systole.

The effect of catecholamines and atrial pacing on the relationship between electrical systole (QT) and mechanical systole (QS2) was studied in 12 normal subjects and in 32 patients. The studied subjects were divided into three groups. Group 1 included 12 normal subjects in whom serial isoproterenol infusions were performed before and after oral propranolol administration, 160 mg daily for 2 days. During the 24-hour control period, the QT was always shorter than the QS2 (from 14 +/- 3 to 19 +/- 4 msec, p less than 0.01), while during isoproterenol infusion the QT was always greater than the QS2 (from 28 +/- 5 to 34 +/- 5 msec, p less than 0.01). Group 2 included 26 patients in whom 24-hour urinary epinephrine (E) and norepinephrine (NE) were measured the same day as systolic time interval measurements. The E + NE was higher in patients in whom the QT was longer than the QS2 compared with patients in whom the QT was the same or shorter than QS2 (107 +/- 9 vs 61 +/- 7 microgram/24 hours, p less than 0.05). Group 3 included six patients in whom the heart rate was increased with atrial pacing, from 80 to 130 beats/min. The QT was always shorter than the QS2 (from 13 +/- 3 to 24 +/- 5 msec, p less than 0.01). Adrenergic stimulation results in a relative prolongation of the QT with the QS2 shortening and the QT remaining unaffected. The QT is normally shorter than the QS2, so the duration of QT should always be considered in relationship to the duration of QS2. Finally, a reversal of the normal QT-Qs2 relationship may provide a simple index of increased adrenergic activity.

Adolescent↗
PubMed1981

Prazosin and hydralazine in congestive heart failure. Regional hemodynamic effects in relation to dose.

Central hemodynamic variables and regional blood flow and vascular resistances were ascertained in patients with severe congestive heart failure before and after the oral administration of prazosin hydrochloride or hydralazine. Prazosin was administered in doses of 2, 5, and 10 mg and hydralazine, 75 and 100 mg. Although both agents significantly increased cardiac output and decreased vascular resistances, their effects on regional blood flow and vascular resistances were considerably different. Prazosin increased hepatic blood flow and reduced hepatic vascular resistance at lower doses; these changes decreased as prazosin was increased. Hydralazine did not significantly alter mean hepatic blood flow or vascular resistance. Prazosin did not affect renal blood flow or renal vascular resistance. In contrast, hydralazine significantly increased renal blood flow and reduced vascular resistance; the changes were dose related. Both drugs augmented limb blood flow and diminished limb vascular resistance; the magnitude of change was dose dependent.

Cardiac Output↗
PubMed1980

Positive inotropic effects of hydralazine in human subjects: comparison with prazosin in the setting of congestive heart failure.

Hydralazine possesses positive inotropic properties in animal model preparations. To determine whether this vasodilator elicits a positive inotropic response in the failing human ventricle, hydralazine, 75 or 100 mg, was administered orally to 14 patients with left ventricular dysfunction and congestive heart failure; the results were compared with those of first-dose prazosin at 5 and 10 mg. The duration of the preejection period and the isovolumic developed pressure/duration of isovolumic contraction (delta P/delta t) were used as indexes of inotropy. Prazosin did not effect a significant response in the duration of the preejection period or in the delta P/delta t. Hydralazine significantly shortened the preejection period and increased the delta P/delta t over 8 hours after administration; these data suggest that hydralazine elicits a positive inotropic response in the failing human ventricle.

Dose-Response Relationship, Drug↗
PubMed1980

Reproducibility of echocardiography in chronic congestive heart failure.

The purpose of this study was to define the reproducibility of serial echocardiographic measurements of left ventricular size and function. Fourteen patients in stable condition after heart failure (Group I) had five weekly outpatient echocardiograms performed by a single technician with blinded interpretation. The average end-diastolic diameter (EDD) of all patients was 68 mm, with a mean standard deviation of 4 mm and a 95% confidence interval of 8 mm. The average end-systolic diameter (ESD) was 58 mm; the 95% confidence interval was 5.6%. A group of four patients with heart failure (Group II) had daily echocardiograms while undergoing continuous hemodynamic monitoring. Pulmonary capillary blood pressure and thermodilution cardiac outputs were stable throughout the 4-day study period. Daily morning echographic measurements were constant, with 95% confidence interval of the EDD being only 4 mm. The ESD and % delta D had 95% confidence intervals of 2 mm and 3.2%, respectively. The narrow range of measurements (narrow confidence intervals) demonstrates the excellent reproducibility of these echocardiographic parameters.

Echocardiography↗
PubMed1980

Long-term benefit of dobutamine in patients with congestive cardiomyopathy.

Dobutamine was given intravenously for three days to 38 patients with congestive cardiomyopathy. The patients were followed by serial determinations of functional class and by non-invasive measurements of left ventricular function-systolic time intervals (PEP/LVET) and echocardiogram (% delta D). The average PEP/LVET declined significantly (p < 0.001) at three days, four and nine weeks, and at 10 months after the discontinuation of dobutamine infusion. Also, 67% (20 of 30) of patients had improvement of the PEP/LVET by greater than -0.04 at seven days. Even two and six months after dobutamine, 58% (15 of 26) and 39% (seven of 18) were improved. Similarly, the % delta D was improved by at least 2% in 60% (18 of 30) at seven days and 55% (16 of 29) at four weeks. At two and six months, 50% (14 of 28) and 42% (10 of 24) were improved. Those patients who did not improve their FC were more likely (five of nine) to have left ventricular free wall thickness (by echocardiogram) less than 0.5 cm./M2. Those who responded usually (22 of 29) had a ventricular wall thickness greater than 0.5 cm./M2. Although the mechanism of the prolonged improvement after a three day infusion of dobutamine is not understood, this study suggests that dobutamine has a role in the therapy of chronic congestive heart failure.

Adolescent↗
PubMed1980

Biatrial electrograms during coarse atrial fibrillation and flutter-fibrillation.

Right and left atrial electrograms were recorded in 57 patients who demonstrated coarse atrial fibrillation or flutter-fibrillation on the scalar electrocardiogram. Atrial electrograms in coarse atrial fibrillation most often showed biatrial fibrillation with periodic slowing and regularity, while dissimilar interatrial or right intra-atrial rhythms were noted less frequently. Flutter-fibrillation on the scalar ECG required the presence of rapid regular tachysystole (flutter) somewhere in the atria and was usually associated with dissimilar interatrial or right intra-atrial rhythms, dissimilar atrial flutter rates, or fast or fragmented flutter. Coarse atrial fibrillation and flutter-fibrillation may be secondary to a variety of atrial electrical events.

Adult↗
PubMed1980

Use of chest wall stimulation to localize and treat pacemaker sensing failure.

A case of pacemaker malfunction in a permanently implanted demand transvenous pacemaker is presented. Complete "failure to sense," resulting in considerable hemodynamic embarrassment, was treated by chest wall stimulation using an external pacemaker and two superficial chest leads applied over the permanent pacemaker generator-lead junction. The technique of this procedure and its usefulness in the localization and temporary therapy of pacemaker sensing failure are discussed.

Cardiac Pacing, Artificial↗
PubMed1980

Triple AV nodal pathways in man?

A 41 year old woman underwent electrophysiological studies for the evaluation of paroxysmal supraventricular tachycardia. AV nodal conduction time and refractory period plots (atrial extra-stimulus technique) suggested the presence of triple AV nodal pathways.

Adult↗