Search PubMed⌕ Search

Biomedical subjects

P C Block

Publications and source records attributed to P C Block.

At least 145 records · Page 8Linked to original sources
PubMed1980

Percutaneous transluminal coronary angioplasty.

Percutaneous transluminal coronary angioplasty, first performed in man in 1977, has been used increasingly in selected patients with angina pectoris due to coronary atherosclerosis. Patients with single-vessel coronary artery disease in whom the stenosis is relatively proximal, noncalcified, discrete, and tapered rather than eccentric are the best candidates for the procedure. Objective evidence of coronary insufficiency documented by scintigraphy or exercise testing allows objective follow-up. Patients must be candidates for coronary artery bypass graft surgery since a complication might require immediate operation. Clinical experience indicates that 60%-85% of patients chosen for coronary angioplasty can have their coronary stenoses successfully dilated. Symptomatic improvement occurs in almost 90% of successful dilatations. Follow-up studies have shown persistent vessel patency for more than 1 year. From 3% to 8% of patients have needed urgent coronary artery bypass graft surgery because of coronary insufficiency developing at the time of angioplasty. Mortality has been less than 1%. The initial favorable experience with coronary angioplasty indicates that it should continue to be evaluated. The limits of patient selection for the procedure and long-term results require further compilation of data.

Adult↗
PubMed1980

The bifocal diverging collimator: a means of simultaneous biplane imaging of the heart during equilibrium radionuclide ventriculography.

We have constructed a bifocal diverging collimator (BDC), capable of simultaneously recording two views of the heart 50 degrees apart on each half of a standard imaging field. In this study, simultaneous two-view blood-pool scans using the BDC were compared with the same two separate views obtained using an all-purpose parallel-hole collimator (PHC), assessing left-ventricular ejection fraction and regional wall motion in 20 patients undergoing contrast left ventriculography (CV). Ejection fraction by BDC correlated closely with PHC (r = 0.94) and with CV (r = 0.88). Regional wall motion was scored qualitatively on a five-point scale from 3 (normal) to--1 (dyskinesis) with an 88% agreement between BDC and PHC and PHC for segment scores. The percentages for agreement between BDC and CV, and between PHC and CV, were identical, 79%. A single blood-pool scan acquisition using a new BDC provides information about global and regional left-ventricular function in two planes, comparable with that of a PHC.

Coronary Disease↗
PubMed1979

Radionuclide-determined change in pulmonary blood volume with exercise. Improved sensitivity of multigated blood-pool scanning in detecting coronary-artery disease.

To assess the clinical usefulness of radionuclide-determined changes in pulmonary blood volume in patients with or without substantial coronary-artery disease, we determined the ratio of pulmonary blood volume at rest as compared with that during exercise. We used multigated blood-pool images obtained at rest and during supine exercise to determine the blood-volume ratio in patients subsequently undergoing coronary arteriography for evaluation of chest pain. Exercise tests were performed by use of a submaximal-workload protocol, although all tests were limited according to each patient's symptoms. The mean exercise/rest pulmonary-blood-volume ratios were lower for persons without coronary-artery disease (0.94 +/- 0.06 [S.D.], 10 patients) and for those with disease confined to the right coronary artery (0.99 +/- 0.12, five patients), as compared with all others with coronary-artery disease (1.14 +/- 0.15, 37 patients) (P less than 0.01). A pulmonary-blood-volume ratio equal to or greater than 1.06 had a sensitivity of 79 per cent. Patients with coronary-artery disease not confined to the right coronary artery usually show an increase in pulmonary blood volume during supine exercise. No such change occurs in persons without coronary-artery disease.

Adult↗
PubMed1979

Predicting results of coronary angiography.

This study compares the ability of various risk factor combinations to predict the extent of coronary artery disease found on coronary angiography. Risk factors were measured in 99 patients prior to coronary angiography. Clinical, epidemiological, psychosomatic, and combined orientations were compared as to their ability to predict angiography results. The clinical orientation was the most successful in predicting vessel disease (p less than .0001), followed by the epidemiological model, which was also successful (p less than .03). In contrast, psychosomatic factors were not accurate predictors of vessel disease. By combining all of the orientations, the accuracy of prediction is improved.

Adult↗
PubMed1979

Patterns of haemodynamic alteration during left ventricular ischaemia in man. Relation to angiographic extent of coronary artery disease.

Haemodynamic changes produced by rapid atrial pacing (60 patients, 52 of whom developed angina) or in association with spontaneous angina (32 patients) were measured in 92 patients with angiographic coronary artery disease. The extent of coronary artery disease was scored by the jeopardy score system (range 0 to 12). The haemodynamic changes induced by ischaemia occurred in 3 patterns: pattern I, no change in filling pressure or in mean systemic arterial pressure; pattern II, a rise in filling pressure and a rise in mean systemic arterial pressure; pattern III, a rise in filling pressure, but no significant change or a fall in mean systemic arterial pressure. In patients who had a pattern II or a pattern III response to ischaemia, the change in mean systemic arterial pressure was linearly related to the corresponding change in cardiac output. The likelihood of a patient showing a given pattern of ischaemia-induced haemodynamic change was related to the extent of coronary artery disease; of 22 patients with jeopardy scores of 2 or 4, 91% exhibited pattern I, 9% pattern II, and none pattern III; of 39 patients with jeopardy scores of 6 or 8, 40% exhibited pattern I, 22% pattern II, and 38% pattern III; of 31 patients with jeopardy scores of 10 or 12, 12% exhibited pattern I, 10% pattern II, and 78% pattern III (P less than 0.01). Among the 54 patients in whom serial cardiac output determinations were available, a decline of the left ventricular function curve during ischaemia was demonstrable in 8% of those with a pattern I response, in 54% of those with a pattern II response, and in 90% of those with a pattern III response (P less than 0.01). The pattern of response was unrelated to resting angiographic left ventricular ejection fraction, whether ST segments became elevated or depressed, or whether ischaemia was pacing-induced or spontaneous. These results suggest that the haemodynamic response to ischaemia is determined by the fraction of the left ventricle that becomes dysfunctional during ischaemia.

Blood Pressure↗
PubMed1979

Preoperative evaluation of subvalular fibrosis in mitral stenosis. A predictor factor in conservative vs replacement surgical therapy.

To assess the degree of mitral subvalvular fibrosis (SVF) in patients with mitral stenosis, left ventriculograms were reviewed, and a mitral subvalvular distance ratio (DR) was determined by dividing the distance from the papillary muscle tips to the closed mitral leaflets in systole by the distance from the aortic valve to the left ventricular apex in diastole. In 15 patients with normal ventricles, the mean DR was 0.244 +/- 0.017. In nine patients with minimal SVF, the mean DR was 0.181 +/- 0.025. In 10 patients with moderate SVF, the mean DR was 0.148 +/- 0.033. In 5 patients with severe SVF, the mean DR was 0.087 +/- 0.009. All mean DRs were mutually distinguishable at p less than 0.01. The clinical results and preoperative DR of 28 patients who had mitral commissurotomy were reviewed. A DR of less than 0.140 precluded a good longterm result from mitral commissurotomy alone. The DR reliably predicts the degree of SVF preoperatively and identifies patients with mitral stenosis who require valve replacement or a direct surgical attack on the subvalvular mechanism.

Angiocardiography↗
PubMed1979

Evaluation of left ventricular free wall asynergy due to coronary artery disease: use of an interlaced ECG-gated radiography system.

A new radiographic technique produces a high quality image of the chest at end systole and end diastole in a single radiograph. A preliminary study of this method for evaluating various degrees of segmental asynergy of the left ventricular free wall in 25 patients with coronary artery disease showed excellent correlation with left ventriculography (r = 0.88). The method showed a high sensitivity (94%) and specificity (96%). It seems potentially useful to increase the information gained from the chest radiograph in patients with cardiac disease.

Coronary Disease↗
PubMed1978

Type A personality and extent of coronary atherosclerosis.

The relation between type A personality and the extent of coronary artery disease was studied in 109 patients who underwent selective coronary angiography. Type A personality as measured with the Jenkins Activity Survey was not correlated with the extent of coronary artery disease as assessed from the number of vessels with 50 percent or greater narrowing of diameter.

Adult↗
PubMed1978

Unexplained in-hospital fever following cardiac surgery. Natural history, relationship to postpericardiotomy syndrome, and a prospective study of therapy with indomethacin versus placebo.

In Part I of this study, the in-hospital course of 219 patients who had undergone a cardiac operation is analyzed. Fever (greater than or equal to 37.8 degrees C, rectal) was present after postoperative day 6 in 159 patients (73%) and was of unexplained cause in 118. Fever decay in the population of unexplained fever patients was exponential. All patients with unexplained postoperative fever were afebrile by postoperative day 19. In-hospital pericardial rub and pleuritic chest pain, widening of the mediastinum on chest film, and pleural effusion were not specifically associated with unexplained postoperative fever. In Part II, 67 patients with unexplained postoperative fever were given indomethacin (100 mg per day) or placebo for 7 days by a randomized, double-blind protocol. Indomethacin resulted in a shorter duration of fever (2.4 vs 3.5 days, P is less than 0.01) and in a shorter duration of chest pain, malaise, and myalgias compared to placebo. Sixty-seven percent of the patients in Part I and all of the patients in Part II were contacted 2-8 months following hospital discharge. Five percent had experienced an illness that we considered to be acute pericarditis, but its occurrence was unrelated to whether the patient had had in-hospital unexplained postoperative fever, in-hospital rub or chest pain, or in-hospital administration of indomethacin.

Cardiac Surgical Procedures↗
PubMed1977

Detection of left atrial myxoma by gated radionuclide cardiac imaging.

Gated radionuclide cardiac blood pool scans (GCS) of end-systole and end-diastole or eight images subtending the entire cardiac cycle were performed on seven patients with left atrial myxomas documented by pulmonary cineangiography with left atrial follow-through. The ethocardiogram was either suggestive or diagnostic in all patients. In addition to demonstration of the tumor (6 patients), the GCS detected three patterns of tumor motion: 1) a defect which moved from the left atrium in end systole to the left ventricle in end diastole (2 patients); 2) a defect which remained within the region of the left atrium but decreased in size between end diastole and end systole (3); and 3) a defect which was observed within the region of the left ventricle in end diastole but disappeared in end systole (1). Thus, the GCS is a noninvasive method for detection and evaluation of motion of left atrial myxomas.

Adult↗
PubMed1977

Hypertrophic cardiomyopathy. Evaluation by gated cardiac blood pool scanning.

The gated radionuclide cardiac blood pool scan (GCS) can be used to visualize the entire profile of the interventricular septum and left ventricular contraction. Twenty-two patients with hypertrophic cardiomyopathy, nine with valvular aortic stenosis and six normals, underwent echocardiography and GCS. All patients with hypertrophic cardiomyopathy had asymmetric septal hypertrophy and 14 of 22 had resting systolic anterior motion of the anterior leaflet of the mitral valve on echocardiogram. In eight patients with aortic stenosis with adequate echocardiograms, two had asymmetric septal hypertrophy and none had systolic anterior motion. The GCS demonstrated disproportionate upper septal thickening in 11; septal flattening in 16; cavity obliteration in 17; and a filling defect in the region of the left ventricular outflow tract in 16 of the 22 patients with hypertrophic cardiomyopathy. In the nine patients with valvular aortic stenosis, two demonstrated septal flattening, two cavity obliteration, two an outflow tract defect, and none disproportionate upper septal thickening. Both patients with cavity obliteration demonstrated asymmetric septal hypertrophy on echocardiogram. One normal control patient had septal flattening. Thus the gated cardiac blood pool scan provides an atraumatic technique for the evaluation of patients with hypertrophic cardiomyopathy which complements the echocardiogram.

Aortic Valve Stenosis↗
PubMed1977

Inhalation imaging with oxygen-15 labeled carbon dioxide for detection and quantitation of left-to-right shunts.

Quantitation of left-to-right shunts was determined noninvasively from the pulmonary clearance pattern of inhaled 15oxygen-labeled carbon dioxide (C15O2). After a single breath inhalation of C15O2, counts over the lungs were obtained from sequential 0.5 sec positron camera images. In 21 patients without left-to-right shunts, counts declined exponentially due to the washout of C15O2 by the pulmonary blood flow. In 22 patients with left-to-right shunts, this monoexponential pulmonary clearance pattern was interrupted by an abnormal upward deviation, indicating tracer recirculation through the shunt to the lungs. Following surgical shung closure in 10 patients, pulmonary C15O2 clearance patterns became normal in nine and showed a small residual left-to-right shunt in one. Shunt size was derived from the ratio of the height of the recirculation curve to the height of the initial inhalation peak. These values significantly correlated with shunt size as determined by oximetry (r = 0.83).

Adolescent↗
PubMed1976

Snaring of a Swan-Ganz catheter.

Insertion of a Swan-Ganz catheter for measurement of pulmonary artery and pulmonary capillary wedge pressures is common for operative management of patients with borderline left ventricular function, particularly patients undergoing cardiac surgery. The transatrial course of the catheter may allow it to lie against the lateral and anterior walls of the right atrium, where it can be caught in a suture used to control bleeding. This report documents such a complication of cardiac surgery: A Swan-Ganz line was caught by a right atrial suture. The tip of the Swan-Ganz catheter was in the distal right pulmonary artery, so that the usual means of removal with a loop-snare catheter was impossible. Instead, a Teflon sleeve, inserted percutaneously was used to stabilize the right atrium while gentle traction was used to break the catheter at its point of entrapment. In this manner, the proximal portion of the catheter was removed. The distal segment of the catheter then was removed with a biopsy forceps inserted percutaneously through the femoral vein.

Cardiac Catheterization↗
PubMed1975

Variant angina pectoris: Clinical and anatomic spectrum and results of coronary bypass surgery.

Twenty patients are described with the variant angina syndrome (recurrent angina at rest with S-T segment elevations occurring only during pain and no evolution of infarction). In contrast to patients previously reported on, all but one had progressive unstable angina before hospitalization. Angina was frequently associated with arrhythmias, including ventricular fibrillation (2 instances), ventricular tachycardia (4), frequent ventricular premature beats (5), atrioventricular block (4), sinus bradycardia (2), sinoatrial exit block (1) and supraventricular tachycardia (1). Seventeen patients had significant proximal stenosis of one or more coronary arteries with good distal vessels. Bypass surgery in 15 of these patients resulted in one noncardiac postoperative death, one perioperative infarction and relief of pain in all 14 survivors. After a 17 month mean follow-up period (range 4 to 38 months), all survivors are pain-free. Three patients had no significant coronary disease; one of these became asymptomatic with medical therapy, one continues to have angina and one died suddenly. Patients with normal coronary arteries could not be distinguished clinically or by electrocardiogram from those with severe obstructive lesions. This experience suggests that all patients with the variant angina syndrome should be studied by coronary angiography, and that most patients with significant fixed coronary lesions will do well after coronary bypass surgery.

Adult↗
PubMed1975

Coronary occlusion during coronary angiography.

Between January 1, 1970, and December 31, 1974, 2981 patients underwent coronary arteriography. Twelve acute coronary dissections or embolizations occurred, an incidence of 0.4%. The incidences of acute occlusions for the Sones and Judkins techniques were 0.19% (4/2077 studies) and 0.88% (8/940), respectively. No instance of acute occlusion has occurred during the past 490 studies performed by the Judkins technique. Eight patients with right coronary artery dissections or circumflex emboli were treated medically. All survived, but in seven a myocardial infarction evolved. Four patients underwent emergency saphenous venous bypass grafting because of refractory ventricular fibrillation (two patients) or because large amounts of myocardium were thought jeopardized (two patients). All patients in this group had interruption of flow supplying the left anterior descending coronary artery. Despite surgical intervention in less than three hours in all patients, survivors all sustained transmural myocardial infarctions. Three patients survived surgery and were discharged home.

Acute Disease↗