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Biomedical subjects

R L Feldman

Publications and source records attributed to R L Feldman.

At least 73 records · Page 4Linked to original sources
PubMed1985

Emergency coronary artery bypass graft surgery for threatened acute myocardial infarction related to coronary artery catheterization.

In 20 patients undergoing cardiac catheterization, usually involving balloon-catheter dilation or streptokinase infusion, catheter-induced coronary artery intimal damage resulted in severe chest pain, electrocardiographic evidence of obstruction or dissection of a major coronary artery. These patients were surgically revascularized within 8 hours after the onset of the acute chest pain syndrome. Our experience with pharmacological and catheter-related manipulations to improve coronary blood flow after the ischemic episode but before operation suggested that the additional time spent in the catheterization laboratory was worthwhile. The injured coronary artery was the left anterior descending in 10 patients, the right in 8, the left main in 1 patient, and an obtuse marginal branch of the circumflex in 1. The average number of grafts per patient was 2.5; only 6 patients had single bypass grafts. In 5 patients, intraaortic balloon pumping was used either preoperatively or postoperatively. Inotropic support was used postoperatively in 5 patients, and 7 patients received lidocaine for ventricular irritability. Abnormal elevation of the serum isoenzyme of creatine kinase (CK-MB) was seen in 8 patients, and new Q waves were noted in 4 patients; 3 of these 4 patients with new Q waves also had abnormal serum CK-MB levels. Global ejection fraction obtained by the equilibrium-gated blood pool scan postoperatively was 60 +/- 3%, which was similar to the 62 +/- 3% obtained from the contrast-determined ventriculogram done preoperatively prior to the catheter-related injury. There were no early or late deaths, but morbidity was much higher in the group who had emergency coronary artery bypass grafting (CABG) compared with those who had elective CABG.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1985

Effect of nifedipine on coronary hemodynamics in patients with left anterior descending coronary occlusion.

The mechanisms responsible for the beneficial effects of calcium channel antagonists in patients with effort angina were investigated by studying the coronary hemodynamic responses of the anterior left ventricular region before and after administration of nifedipine in 13 patients whose left anterior descending coronary artery was filled by flow from collateral vessels. Nifedipine was given bucally in a dose (10 or 20 mg) that decreased aortic pressure 5 mm Hg or more. Nifedipine increased collateral flow (regional thermodilution) in only three patients (p = NS), but consistently decreased coronary resistance in the left ventricular anterior region (p less than 0.05). Anterior region myocardial oxygen consumption did not change after nifedipine administration. Lactate metabolism was evaluated in eight patients: values were abnormal in four patients before nifedipine; after nifedipine, values remained abnormal in three of these patients and became abnormal in one other. During atrial pacing stress, angina occurred in all patients before nifedipine and at the same or lower heart rate in nine patients after nifedipine. After nifedipine administered at the same rate that induced angina during the control period, collateral flow and myocardial oxygen consumption were usually lower (both p less than 0.05), but anterior region coronary resistance was unchanged compared with control values. Lactate metabolism was not usually improved. Thus, although nifedipine maintained collateral flow while aortic pressure decreased, no consistent beneficial effect on pacing-induced angina was seen.

Adult↗
PubMed1985

Regional coronary hemodynamic responses during the cold pressor test: lack of effect of nitroglycerin.

The effects of large coronary vessel dilation on responses to immersion of a hand and forearm in ice water for 1 minute (that is, the cold pressor test) were calculated for 17 patients. Regional coronary blood flow and aortic and left ventricular pressures were continuously measured before and during two cold pressor tests, each performed before and after administration of sublingual (0.4 mg) or low dose intracoronary (0.01 mg) nitroglycerin. During the initial cold pressor test, heart rate and coronary pressures increased in all patients; total and regional coronary resistance usually increased in patients with severe coronary artery disease and usually decreased in patients with a normal coronary angiogram. Sublingual nitroglycerin induced important systemic effects, but intracoronary nitroglycerin did not; both induced dilation of coronary arteries viewed angiographically. Regardless of the route of nitroglycerin administration, coronary hemodynamic responses were directionally similar during the repeat cold pressor test compared with the initial one. These data support the concept that changes in tone of the large coronary arteries are not important in producing the cardiac responses observed during the cold pressor test.

Adult↗
PubMed1985

Calcium antagonists.

At present nitrates remain the initial treatment for relief or prevention of angina in patients with coronary artery disease. In cases where nitrates and beta blockers have been used and are ineffective for managing effort angina, calcium antagonists may be substituted or added to the beta-blocking treatment. When the predominant symptom is rest angina, and there is evidence suggesting coronary artery spasm, nitrates and a calcium antagonist can be effective therapy. In patients with heart block, bradyarrhythmias, heart failure, or hypertension nifedipine may be the drug of choice. In contrast verapamil merits choice when supraventricular tachycardia is present. Diltiazem appears intermediate between nifedipine and verapamil and may be particularly useful when hypotension or other side effects must be avoided.

Adrenergic beta-Antagonists↗
PubMed1985

Laser recanalization of occluded atherosclerotic arteries in vivo and in vitro.

Controlled laser irradiation was used to recanalize atherosclerotic stenoses in vivo and in vitro. In 15 rabbits with atherosclerotic arteries a catheter was positioned in the distal aorta for angiographic examination and as a guide for a small silica optical fiber. Both Nd-YAG and argon lasers were used for recanalization with varying power and duration. As determined by angiographic studies the severity of iliofemoral stenoses in eight 15 arteries decreased from 78 +/- 18% to 32 +/- 11% (mean +/- SD). In one additional artery the stenosis improved from 45% to 25%, but this was associated with perforation. The other six arteries were perforated (two after fiber manipulation, four after laser discharge) without obvious improvement in severity of stenosis. No angiographic loss of distal circulation was noted. To better define tissue- laser interactions in the live-rabbits, lasing of 15 totally occluded atherosclerotic rabbit arterial segments in vitro was done while the optical fiber was advanced or fixed. When the fiber was fixed, serial sections showed that the new lumen was flame shaped. The width and depth of the lumen increased with increasing laser energy. When the fiber was advanced, histologic examination showed a smooth cylindrical vascular channel with limited lateral tissue damage. This study demonstrated that lasers can recanalize atherosclerotic stenoses in a live animal preparation; however, arterial perforation remains a problem.

Animals↗
PubMed1984

Effect of nitroglycerin on coronary collateral flow and pressure during acute coronary occlusion.

Coronary collateral function was evaluated in 21 conscious, unsedated patients by measuring aortic and distal coronary pressures and great cardiac vein flow during transient (1 minute) balloon occlusion of the anterior descending artery in the course of coronary angioplasty. Measurements were made before and during administration of intravenous nitroglycerin (NTG). Clinical, electrocardiographic and hemodynamic events of transient myocardial ischemia occurred in 10 patients before and 6 patients during NTG administration (p = 0.11). The NTG infusion consistently decreased pressure determinants of myocardial oxygen demand without increasing heart rate. NTG also decreased a calculated coronary collateral resistance index in 13 patients. Responsiveness to NTG did not appear to depend on the presence or absence of collateral vessels detected by angiography or on any other angiographic variable assessed. Measurement of coronary collateral function during coronary angioplasty is a new technique with the potential to assess the ability of interventions to prevent transient myocardial ischemia and improve myocardial perfusion during acute coronary occlusion in humans.

Adult↗
PubMed1984

Effects of acute coronary occlusion on hemodynamics in an adjacent coronary artery in dogs.

The effects of acute occlusion of 1 coronary artery on flow responses in another were studied in 24 open-chest dogs. Left circumflex (LC) flow was measured with and without LC stenoses before and during reactive hyperemia. In 19 dogs the left anterior descending artery (LAD) was occluded and measurements were repeated after 1 hour (group 1). Four dogs had measurements before and after 1 hour without LAD occlusion (group 2). In group 2 no systemic, left ventricular (LV) or coronary hemodynamic changes were observed after 1 hour. In group 1, an hour after LAD occlusion, heart rate and aortic pressure had not changed but stroke volume decreased slightly (-8 +/- 7%, mean +/- SD, p = not significant) and LV end-diastolic pressure had increased (2 +/- 3 mm Hg, p less than 0.05). Basal LC flow was not changed by less than 90% LC stenosis. Ninety percent LC stenosis decreased LC flow both before and after LAD occlusion. During reactive hyperemia without LC stenosis, LC flow decreased after LAD occlusion in 15 of 19 dogs (from 154 +/- 80 to 141 +/- 75 ml/min, p less than 0.05). With 60 and 80% LC stenoses, LC flow during reactive hyperemia decreased before LAD occlusion (110 +/- 62 and 74 +/- 40 ml/min, respectively), but decreased further (both p less than 0.05) after LAD occlusion (98 +/- 54 and 63 +/- 43 ml/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Left ventricular changes resulting from chronic aortic regurgitation in dogs.

Chronic aortic regurgitation (AR) was induced by aortic valve perforation using catheterization techniques in 7 closed-chest puppies. Approximately 2 years after the creation of AR in these puppies, their growth was similar to that in littermate controls. A gradually progressive degree of left ventricular (LV) dilation and hypertrophy occurred as LV end-diastolic volume (average 116%) and mass (average 114%) increased in animals with AR compared with that in the littermate controls. The technique described to induce AR did not interfere with the normal growth and development of the animals, and permitted study of the functional characteristics of the resulting LV dilation and hypertrophy without added effects of thoracotomy and pericardiotomy.

Animals↗
PubMed1984

A new model for investigation of transluminal recanalization: human atherosclerotic coronary artery xenografts.

A model for testing transluminal recanalization techniques was developed. Human atherosclerotic arteries were transplanted in dogs and evaluated by angiographic and histologic study within a 12-week period. An inflammatory response was most intense within the first 2 weeks. By 12 weeks, no inflammation was noted. The model has several advantages: (1) The pathologic characteristics are those of a human coronary artery. (2) Thrombus formation is frequent, with progression to a well organized dense fibrocellular vascular occlusion within 4 to 12 weeks. (3) The arterial occlusion resembles human vascular disease. (4) The vascular occlusions are readily accessible with standard catheterization technique. (5) The model is easy to produce within a short period. This model has been used to evaluate laser recanalization of vascular obstructions.

Angiography↗
PubMed1984

Hemodynamic effects of nitroglycerin combined with diltiazem in patients with coronary artery disease.

Resting coronary and left ventricular hemodynamic effects of diltiazem and nitroglycerin, given intravenously in combination, were studied in 12 patients with coronary heart disease. Results observed with this combination were compared with those in seven patients given diltiazem initially (group I) and five patients given nitroglycerin initially (group II). The diltiazem-nitroglycerin combination reduced systolic blood pressure 27 percent (p less than or equal to 0.05) with no significant change in heart rate to affect a 22 percent (p less than or equal to 0.05) decrease in the rate-pressure product. Left ventricular end-diastolic pressure (-36 percent) and dp/dt (-6.4 percent) both declined (p less than or equal to 0.05). Coronary flow and cardiac output were both maintained. Diltiazem alone and nitroglycerin alone also reduced systolic pressure and the rate-pressure product but to a lesser degree than the combination. Diltiazem did not significantly affect left ventricular end-diastolic pressure and dp/dt. Nitroglycerin reduced left ventricular end-diastolic pressure to an extent similar to the reduction produced by the combination but increased heart rate whereas this determinant of myocardial oxygen demand did not increase significantly with the combination. These findings suggest that the combination of diltiazem and nitroglycerin produces a greater reduction in myocardial oxygen demand than either drug alone. In addition, the combination maintains coronary blood flow without increases in determinants of myocardial oxygen demand. This potentially beneficial drug combination warrants further trial in patients with myocardial ischemia.

Benzazepines↗
PubMed1984

Evaluation of coronary collateral circulation in conscious humans.

The physiologic importance of coronary collateral vessels was investigated in 19 men undergoing transient proximal occlusion of the left anterior descending (LAD) branch without sedative medication. No vasodilators were given before LAD balloon occlusion. Six men had angiographic filling of the LAD via coronary collateral vessels (Group 1) and 13 did not (Group 2). Aortic, distal coronary and left ventricular (LV) filling pressures and great cardiac vein blood flow (thermodilution) were recorded continuously during occlusion. During LAD occlusion, clinical and electrocardiographic evidence for transient myocardial ischemia occurred more often in patients in Group 2 than in Group 1, but the difference was not statistically significant. Heart rate and aortic and distal coronary pressures were similar in Groups 1 and 2. LV filling pressure was 3 mm Hg higher in Group 2 patients (p less than 0.05). The aortic to distal coronary pressure difference and the distal coronary to LV filling pressure difference were also similar in Groups 1 and 2. However, residual great cardiac vein flow was 55% higher (p less than 0.05) and the calculated coronary collateral resistance index was 45% lower in patients in Group 2 compared with those in Group 1 (p less than 0.01). Coupling of regional coronary venous blood flow estimates to pressure measurements routinely made during angioplasty is a new technique that allows evaluation of determinants of coronary collateral function in conscious humans.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Percutaneous brachial catheterization using a modified sheath and new catheter system.

An alternative method for left heart catheterization via the brachial artery, without cutdown, is described. Percutaneous brachial catheterization was done with a modified 7F side-arm sheath with check valve. A modified 7F high flow catheter was developed employing characteristics of both multipurpose and Sones catheters. The technique was used in 100 patients for left heart catheterization, in patients with and without aortic valve disease, for left ventricular angiography and selective coronary angiography. There were no failures or serious complications. All puncture sites were managed with 15-20 minutes of compression using only a blood pressure cuff or finger pressure. Bleeding was controlled with restoration of the radial pulse in all but one patient, who had severe peripheral brachial atherosclerosis. Cutdown and thrombectomy performed before he left the laboratory using standard catheterization techniques promptly restored blood flow. It is our impression that this technique facilitated outpatient catheterizations, repeat catheterizations at sites of previous cutdowns, and reduced patient discomfort.

Adult↗
PubMed1984

Percutaneous transluminal coronary angioplasty in acute myocardial infarction.

Percutaneous transluminal coronary angioplasty (PTCA) has, in general, been restricted to therapy for patients with angina pectoris. Thrombolytic therapy and guide wire recanalization have been used to recanalize coronary arteries in patients with evolving myocardial infarction. Recently we and others have examined the use of PTCA to recanalize the acutely occluded artery associated with the early evolving phase of myocardial infarction. PTCA was performed as definitive therapy in eight patients with acute myocardial infarction. Seven of these had totally occluded arteries to the region of infarct. The infarct-related artery was open within 20 minutes in each of these cases. PTCA recanalization resulted in evidence for reperfusion in each case. Residual stenoses either were not present or were minimal. The procedure was well tolerated. These preliminary results suggest that PTCA may be a reasonable alternative to intracoronary thrombolytic therapy in certain patients with acute evolving myocardial infarction.

Adult↗
PubMed1984

Intracoronary streptokinase in evolving acute myocardial infarction.

Intracoronary application of thrombolytic agents, particularly streptokinase, can recanalize arteries that had been totally occluded in patients with evolving acute myocardial infarction (AMI). Numerous uncontrolled trials have testified to the effectiveness of thrombolytic therapy in most patients in reestablishing flow to the infarct-related coronary artery. Follow-up of patients in whom reperfusion has been established has often demonstrated small but significant increases in the left ventricular ejection fraction. In contrast, in other patients in whom thrombolytic therapy failed to reopen the occluded vessel, the left ventricular ejection fraction usually does not change during follow-up. In most reported uncontrolled trials, few complications are described and the mortality rate in patients treated by this therapy may be lower than expected. These data have been used as the basis for widespread application of this technique in many catheterization laboratories around the world. Our initial experience at the University of Florida in 23 patients has not been as successful as other uncontrolled trials previously reported. Reperfusion was accomplished in only 12 patients. Of 17 who survived their AMI, only five demonstrated an improved left ventricular ejection fraction of at least 10%. Serious complications, including bleeding from catheterization sites or allergic reactions to streptokinase, occurred. Controlled trials to critically evaluate this new therapy are needed and are in progress.

Clinical Trials as Topic↗
PubMed1984

Intraoperative balloon-catheter dilatation: University of Florida experience.

Thirty-four patients with stable angina underwent coronary artery bypass surgery with supplemental intraoperative coronary artery balloon-catheter dilatation. Coronary dilatation was performed on 35 vessels at 50 sites. The balloon catheter could not be passed through one stenotic site. Intimal dissection occurred at two sites, as noted on early postoperative angiographic studies, with resolution on follow-up studies. There was one perioperative myocardial infarction, 100% early relief of angina, and one operative death. Of 25 distal arterial narrowings studied early by angiography (mean, 10 days), 15 (60%) were unchanged, two (8%) were worse, and eight (32%) were improved. Discrete narrowings improved more than diffuse narrowings; in 46% of the former there was an increase in luminal diameter, in comparison to only 17% of the latter. During a maximal 34-month follow-up period, two patients developed recurrent angina and one died of congestive heart failure. Of 13 distal coronary narrowings studied late (mean, 1 year), six (46%) were unchanged, three (23%) were worse, and four (31%) were improved. Postoperative serial catheterization (early and late) of 10 distal narrowings revealed that nine were unchanged and one was worse. Adjunctive intraoperative coronary balloon-catheter dilatation can be performed safely with acceptable clinical results. The procedure may also allow more complete revascularization of the myocardium.

Angina Pectoris↗