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Biomedical subjects

R L Feldman

Publications and source records attributed to R L Feldman.

At least 127 records · Page 7Linked to original sources
PubMed1982

Action of intracoronary nitroglycerin in refractory coronary artery spasm.

Coronary artery spasm usually responds to sublingual nitroglycerin. This report describes four patients with variant angina and one patient with rest angina who had coronary spasm that was refractory to sublingual or i.v. nitroglycerin. In four patients, spasm occurred spontaneous and in one patient after 0.05 mg of ergonovine. In each case, 25-100 micrograms of intracoronary nitroglycerin promptly (30-45 seconds) resulted in reopacification of the vessel involved in spasm and resolution of evidence for ischemia. Thus, intracoronary nitroglycerin can reverse coronary artery spasm that does not respond to systemic nitroglycerin administration.

Adult↗
PubMed1982

Analysis of coronary responses to various doses of intracoronary nitroglycerin.

We studied the degree of coronary artery dilation resulting from increasing doses of intracoronary nitroglycerin (NTG). Heart rate, aortic pressure and coronary artery angiograms were recorded before and after 5-, 50-, 150- and 250-microgram doses of NTG infused into the left main coronary artery. Coronary artery diameters were measured by a magnification angiographic technique. After intracoronary NTG, heart rate was unchanged 2 minutes after each dose. Mean aortic pressure was unchanged after 5 microgram (NS), but declined 5 mm Hg (mean) after 50 microgram, 9 mm Hg after 150 microgram and 18 mm Hg after 250 microgram (all p less than 0.05) compared with before NTG. The maximal increase in diameter occurred after 150 microgram, and no additional increase was seen after 250 microgram. After 5- and 50-microgram doses, 67% and 75% maximal dilation responses, respectively, were observed. Compared with coronary artery diameter before NTG, the 150-microgram dose increased the diameter of left main coronary artery by 5%, proximal coronary artery segments by 9%, middle segments by 19%, distal segments by 34%, collateral-filled coronary arteries by 38%, coronary artery stenoses by 5%, and small coronary arteries (0.4-1.0 mm) by 54%. These data indicate that relatively small doses of intracoronary NTG produce potentially important coronary artery dilation without important changes in heart rate and aortic pressure. These observations should prove helpful in choosing dosage schedules for intracoronary NTG.

Aged↗
PubMed1982

Severe intracoronary thromboxane release preceding acute coronary artery occlusion.

Abnormalities of thromboxane (TXA2)-prostacyclin (PGI2) balance have been described in patients with coronary artery disease. Whether these abnormalities precede or follow an acute coronary event is debated. We report a patient in whom spontaneous acute right coronary artery occlusion was observed during coronary angiography. Measurements of arachidonic acid metabolites demonstrated imbalance in TXA2-PGI2 equilibrium preceding coronary occlusion. Marked increase in TXA2 in coronary sinus but not in the aortic blood suggested intracoronary release. Absence of PGI2 in the coronary venous blood at baseline and during tachycardia stress was evidence for failure of atherosclerotic coronary vessels to generate PGI2.

6-Ketoprostaglandin F1 alpha↗
PubMed1981

Echocardiographic analysis of systolic and diastolic left ventricular wall motion during transient myocardial ischemia.

Left ventricular (LV) wall motion (anterior and posterior) and simultaneous LV pressure were recorded during 30-second left anterior descending (LAD) or circumflex (CX) coronary artery occlusions in open-chest dogs to provide an echocardiographic model of the evolution of wall motion changes during myocardial ischemia. Prominent diastolic echocardiographic motion changes of progressive decrease in LV wall rapid-filling velocities (RFS), slow-filling velocities (SFS), and increased end-diastolic diameter were accompanied by a marked increase in initial and end-diastolic pressures (150% and 70%, respectively; all p less than 0.05). Early (within ten seconds) and progressive decrease in rat (SES), amplitude (E), and duration (TTR) of systolic motion were noted with an increased systolic diameter (p less than 0.05). Ischemic regions developed a characteristic pattern with early relaxation followed by a diastolic inward motion (DIM). These observations confirm and extend other investigators' findings on the motion of the ischemic myocardium and may be applicable to responses to transient myocardial ischemia noted in humans.

Animals↗
PubMed1981

Regional coronary angiographic observations during cold stimulation in patient with exertional chest pain: comparison of diameter responses in normal and fixed stenotic vessels.

In 12 patients with exertional chest pain, coronary angiography was performed and quantitative measurements coronary artery (CA) diameters were made before and during cold stimulation (four normal CA patients and eight fixed CA stenosis patients). The left main CA; proximal, middle and distal anterior descending and circumflex segments; and small intramyocardial CAs (0.4 to 1.0 mm) usually showed only minimal and similar degree of vasoconstriction (average diameter reduction 6%) during cold stimulation in both normals and CA disease (CAD) patients. Magnitude of vasoconstriction differed among some CA segments measured; the left main CA segment (0 +/- 2%, mean +/- SD) usually did not change while distal segments (-10 +/- 10%) usually demonstrated greatest percentage vasoconstriction. Coronary stenoses and CAs filled by collaterals did not demonstrate increased magnitude of vasoconstriction compared to other CAs. Results of other CA segments were also similar comparing patients with and without CAD. The minimal degree of vasoconstriction observed in these CA segments does not appear to account for the large increase in coronary resistance reported during cold stimulation in CAD patients.

Cardiac Catheterization↗
PubMed1981

Effect of diltiazem in patients with variant angina: a randomized double-blind trial.

Effects of diltiazem of frequency of angina and nitroglycerin (NTG) consumption were studied in 12 patients with variant angina (rest pain with ST elevation). Either diltiazem in two dosage schedules (120 mg/day and 240 mg/day), or placebo was administered in a randomized double-blind program over 10 weeks. Significant decreases in angina frequency and TNG consumption were observed when diltiazem treatment periods were compared to placebo periods. Furthermore, when placebo periods following diltiazem were compared to placebo periods following placebo, significant "carry-over" effect with respect to reduced angina frequency was observed. No patient had an increase in angina frequency or TNG consumption on diltiazem compared to placebo. No "rebound effects" or changes in blood pressure or heart rate were observed. One patient complained of dry mouth on diltiazem. These findings, although in a limited number of patients, suggest that diltiazem is effective in decreasing angina frequency and TNG consumption in patients with variant angina. These encouraging results warrant evaluation of diltiazem in a larger patient population over a longer time period.

Adult↗
PubMed1981

Magnitude of dilatation of large and small coronary arteries of nitroglycerin.

Vasodilatory responses of segments of large epicardial left coronary artery (CA), small intramyocardial CAs (0.3-1.0 mm), coronary stenoses and CAs filled by collaterals were determined in 34 patients. Measurements were made before and after nitroglycerin (0.4 mg, sublingual) by means of quantitative magnification coronary angiography using photospot film and a calibrated 6-power viewing device. The left main CA, proximal, middle and distal anterior descending and circumflex segments, and small CAs showed dilatation that varied in magnitude. When magnitude of dilatation was compared with control diameter of the vessel and its location, control diameter proved to be the significant independent variable. CAs with the smallest control diameter showed the greatest magnitude of vasodilatation. CA branches filled by collaterals had vasodilatation similar in magnitude to that of CAs of comparable control diameter. Although coronary stenoses dilated, the magnitude of dilatation was less than that observed in nonstenosed arterial segments of similar control diameter. When areas of stenosis were excluded, however, results were similar regardless of whether the patient had CA disease. These data indicate that a principal determinant of the CA vasodilatory response to nitroglycerin is the size of the artery before nitroglycerin.

Adult↗
PubMed1981

Acute effect of intravenous dipyridamole on regional coronary hemodynamics and metabolism.

The acute coronary hemodynamic and metabolic effects of intravenous dipyridamole were studied in 13 patients. Total left ventricular (LV), anterior (supplied by the left anterior descending coronary artery) and inferior (supplied by circumflex and right coronary arteries) regional flows and metabolic responses were assessed from the coronary sinus and great cardiac vein. Perfusion to LV regions was classified as potentially "normal" or "abnormal," based on coronary angiographic findings. Before dipyridamole, coronary flow, LV oxygen delivery and lactate extraction in both the normal and abnormal regions were similar. Within 1 minute after injection of 20 mg of dipyridamole by i.v. bolus, total coronary flow increased 51% (p less than 0.05). Fifteen minutes after injection the flow increase persisted. Flow decreased to approximately control level by 20 minutes. The major component of this increased total coronary flow resulted from increased flow in normal regions (75% at 1 minute, p less than 0.05). Mean regional LV oxygen delivery and lactate extraction were not changed significantly in either normal or abnormal regions. However, lactate production occurred more often after dipyridamole in abnormal regions. These results suggest that during dipyridamole-induced hyperemia, regional coronary flow and metabolic responses depend upon the status of the arteries supplying the LV region. Regional differences in flow and metabolism occur independent of major changes in heart rate and aortic and LV pressures.

Adult↗
PubMed1981

Quantitation of aortic insufficiency using a catheter-tip velocity transducer.

Bidirectional instantaneous aortic root blood flow was measured in 18 patients with aortic insufficiency (AI) using a catheter-tip velocity transducer. The magnitude of AI was quantitated by determining total forward systolic flow from the area of the flow velocity curve above the zero baseline and regurgitant diastolic flow from the curve area below the baseline. Effective forward flow (stroke volume) was calculated as the difference between total forward systolic flow and regurgitant diastolic flow. Regurgitant fraction was determined as the ratio of regurgitant flow to total forward flow. These data were compared with conventional angiographic estimates (1+ to 4+) of the degree of insufficiency. Velocity transducer determination of regurgitant fraction was 26% in the patient with 1+ AI, 37% (31-48%) in 2+ AI, 49% (35-61%) in 3+ AI and 72% in 4+ AI (regurgitant fraction vs angiographic grade, r = 0.84). Regurgitant flow per diastole was 9 ml in the patient with 1+ AI, 39 ml (20-49 ml) in 2+ AI, 57 ml (31-102 ml) in 3+ AI and 183 ml (143 and 223 ml) in 4+ AI (regurgitant diastolic flow vs angiographic grade, r = 0.73). Good correlation (r = 0.90) was found between values of regurgitant flow obtained from the left ventriculogram and those obtained using the velocity transducer. Although the overall association was good, wide, variability in regurgitant fraction and regurgitant flow was found in the 15 patients with 2+ to 3+ AI. These results suggest that the electromagnetic velocity catheter offers a simple technique for quantitating AI.

Adolescent↗
PubMed1981

Pathogenesis and pathophysiology of ischemic heart disease.

Animal experiments illustrating the effects of coronary artery disease are described. These experiments show marked blunting of reactive hyperremia with 80% of narrowing, and markedly decreased resting blood flow with 90% narrowing of the coronary artery. With 60% stenosis, blunting of hyperemic response occurs with a 5 mm long stenosis and decreased resting blood flow with a 10 mm long stenosis. Further reduction of resting blood flow is demonstrated with serial narrowing. In 6 patients with variant angina, resting myocardial blood flow decreased during episodes of spontaneous angina. Similar results were found in 13 patients with variant angina after ergonovine administration.

Animals↗
PubMed1980

Effects of transient regional ischemia on left ventricular diastolic function.

Simultaneous left ventricular echograms and high-gain pressure recordings were made during 30 s of regional myocardial ischemia induced by snare occlusions of the proximal left anterior descending (LAD) or left circumflex (LCx) coronary arteries in open-chest dogs. Left ventricular diastolic diameter (d) and pressure (p) were measured during slow filling. A normalized (for diameter D) distensibility estimate (DE = delta d/delta p/D) was calculated, as were slow filling slopes (SFSs) of the septum and posterior wall. After occlusion, significant (p less than 0.05) decreases of DE and anterior and posterior left-ventricular-wall mid-diastolic normalized slow-filling slopes (ASFS/D and PSFS/D) were observed. Correlations were noted between percentage decreases of DE and ASFS/D (r = 0.69, p less than 0.0001) and PSFS/D (r = 0.62, p less than 0.0001). No significant differences between decreases of DE and SFS were noted between ischemic and non-ischemic regions. Transient regional myocardial ischemia was associated with a generalized alteration in left ventricular filling patterns in mid-diastole.

Animals↗
PubMed1980

Acute haemodynamic effects of oral prazosin in severe mitral regurgitation.

Acute haemodynamic effects of single dose oral prazosin were studied in eight patients with mitral regurgitation. Heart rate, mean systemic arterial pressure, pulmonary arterial pressure, left ventricular filling pressure, and forward cardiac output were measured in all patients. At peak effect, prazosin reduced mean systemic arterial pressure (95 +/- 4 to 86 +/- 4 mmHg), pulmonary arterial pressure (45 +/- 6 to 23 +/- 4 mmHg), and left ventricular filling pressure (30 +/- 4 to 21 +/- 3 mmHg). Pulmonary and systemic vascular resistance also fell (316 +/- 49 to 208 +/- 43 dynes s cm-5 and 2132 +/- 148 to 1491 +/- 94 dynes s cm-5, respectively). Forward cardiac index increased from 1.89 +/- 0.12 to 2.43 +/- 0.13 l/min per m2 and stroke volume from 43 +/- 5 to 57 +/- 6 ml/beat after prazosin. The onset of these changes occurred between 15 and 30 minutes, peaked between 45 and 60 minutes, and persisted for six hours. These data indicate that in patients with mitral regurgitation oral prazosin promptly improves cardiac performance (judged by increased forward cardiac output and reduced left ventricular filling pressure) as systemic and pulmonary vascular resistance are reduced.

Adult↗
PubMed1980

Effect of graded narrowing of left main coronary artery on left ventricular function.

The relationship between left ventricular function and coronary blood flow was studied in 16 chloralose-anesthetized dogs with an intact coronary circulation and left ventricle. Left ventricular dimensions, hemodynamic function indices, and coronary blood flow were measured simultaneously as the origin of the left coronary artery was narrowed by a calibrated snare. With a left coronary blood flow reduction of 17% (average), left ventricular minor axis diameter increased and maximum aortic blood flow acceleration and maximum rate of rise of left ventricular pressure decreased. Other measured indices of ventricular function did not change significantly. Larger coronary flow decrements caused a decrease in aortic systolic and diastolic pressures, stroke volume and cardiac output and an increase in heart rate and left ventricular end-diastolic pressure. These results confirm a close relationship between left ventricular function and blood supply.

Animals↗