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Biomedical subjects

H O Hirzel

Publications and source records attributed to H O Hirzel.

At least 55 records · Page 3Linked to original sources
PubMed1981

[The left ventricular function in bicycle ergometric stress before and after aortocoronary bypass surgery].

Biplane left ventricular cineangiograms and pressure measurements were performed in 44 patients with coronary heart disease at rest and during submaximal or symptom-limited supine bicycle exercise before and 7 +/- 3 months after bypass surgery. Revascularization was complete in 12 (group 1) and incomplete in 32 patients (group II). Preoperative left ventricular ejection fraction (EF) was within normal limits at rest and declined during exercise in both groups (group I from 59 to 51%, p less than 0.01; group II from 61 to 48%, p less than 0.001). Postoperative EF at rest was nearly identical to preoperative EF in both groups and remained unchanged during exercise (group I from 65 to 63%; group II from 58 to 56%). Peak systolic pressure to end-systolic volume index ratio (LVSP/ESVI in mm Hg/ml . m-2) also decreased during exercise in both groups peroperatively (group I from 3.7 to 3.2 [n.s.]; group Ii from 3.4 to 2.6, p less than 0.005). Postoperative LVSP/ESVI at rest was again unchanged as compared to preoperative LVSP/ESVI. During exercise, however, it increased in both groups, reaching higher values in group I than in group II (5.1 vs. 3.7, p less than 0.05). Whereas both parameters indicate improvement of global left ventricular function following surgery, LVSP/ESVI also suggests more marked recovery of function in patients with complete revascularization than in those where revascularization is incomplete.

Adult↗
PubMed1981

Left ventricular function during exercise before and after bypass surgery.

Biplane left ventricular cineangiograms and pressure measurements were performed in 44 patients with coronary heart disease at rest and during submaximal or symptom-limited supine bicycle exercise before and 7 +/- 3 months after bypass surgery. Revascularization was complete in 12 (group I) and incomplete in 32 patients (group II). Preoperative left ventricular ejection fraction (EF) was within normal limits at rest and declined similarly during exercise in both groups (group I from 59 to 51%, p less than 0.01; group II from 61 to 48%, p less than 0.001). Postoperative EF at rest was nearly identical to preoperative EF in both groups (group I, 65%; group II, 58%) and remained unchanged during exercise (group I, 63%; group II, 56%). Peak systolic pressure to end-systolic volume index ratio (LVSP/ESVI in mm Hg/ml . m-2) also decreased during exercise in both groups preoperatively (group I from 3.7 to 3.2, NS; group II from 3.4 to 2.6, p less than 0.005). Postoperative LVSP/ESVI at rest was again unchanged as compared to preoperative LVSP/ESVI. During exercise, however, it increased in both groups reaching higher values in patients of group I than of group II (5.1 versus 3.7, p less than 0.05). Whereas both parameters indicate an improvement in global left ventricular function following surgery, LVSP/ESVI even suggests a more sizable recovery of function in patients with complete as compared to those with incomplete revascularization.

Adult↗
PubMed1980

[Myocardial scintigraphy with thallium 201 in assessing revascularization procedures by aortocoronary bypass or coronary dilatation].

40 patients underwent aortocoronary bypass surgery for coronary artery disease involving a single vessel in 2 cases, 2 vessels in 10 cases, and all 3 vessels in 28 cases. Preoperative exercise Thallium 201 scanning showed one or several zones of hypofixation (80 p. 100 of maximum myocardial fixation) which were not present at rest. After surgery, exercise scanning was normal in 22 out of 24 patients with normalised or improved vascularisation on control angiography, but remained pathological in 2 cases. However, comparable areas of hypoperfusion were observed in 16 patients with no improvement or worsening of vascularisation after operation. The exercise EG remained pathological in 6 out of 24 patients with normalised or improved vascularisation and in 11 out of 16 patients with identical or worsened vascularisation. In addition, 10 of the 24 patients with improved or normalised vascularisation, and 12 of 16 patients with identical or worsened vascularisation, continued to have chest pain after operation. A zone of hypoactivity was observed in the preoperative exercise scan in 18 out of 20 patients with isolated stenosis treated by catheter dilatation. Normalised exercise scans were recorded in all patients in the month following dilatation, but the exercise ECG remained pathological in 3 patients. In conclusion, 201 Thallium scanning gives a good assessment of myocardial vascularisation after revascularisation procedures. It helps identify patients with non-anginal post-operative chest pain, and detects residual ischaemia in patients without ischaemic signs on electrocardiography.

Adult↗
PubMed1979

[Determinants of left ventricular function in aortic stenosis. Analysis based on pre and postoperative hemodynamic studies].

In 11 preoperative patients with aortic stenosis the isovolumic contractile indices Vpm and Vmax were normal (group N). In 8 patients with aortic stenosis these indices were depressed (group D). Peak systolic circumferential wall stress (afterload) did not differ in the two groups and showed a similar decrease after successful valve replacement. Left ventricular ejection fraction increased significantly in group D from 48 to 71% and remained unchanged in group N (70 and 75%). It is concluded that the significant improvement in ejection performance in group D at similar afterload conditions as in group N is indicative for an impaired preoperative myocardial contractile state.

Aortic Valve Stenosis↗
PubMed1979

[Radionuclide determination of the left ventricular ejection fraction under stress: comparison with angiocardiography].

Left ventricular ejection fraction (LVEF) determined by first pass radionuclide (Nucl.) and biplane contrast angiocardiography (Angio.) was compared in 62 patients with suspected coronary artery disease under resting conditions and in 32/62 patients during bicycle ergometry at identical work load. At rest both methods correlated with r = 0.81 with similar heart rates in both determinations. The mean value of LVEF (Nucl.) was lower than the mean value of LVEF (Angio.), at 50 +/- 2 (SE) % and 58 +/- 2% respectively (p less than 0.001). During exercise a significant correlation between the two methods was again found (r = 0.76). This time no difference was detected between the mean values for LVEF (50 +/- 3% [Nucl.] vs 48 +/- 2% [Angio.], n.s.), which may be explained by the higher heart rates during the invasive study (123 +/- 5/min [Angio.] vs. 108 +/- 4/min [Nucl.], p less than 0.001), resulting in a higher degree of ischemia and hence a lower LVEF. The interobserver variability did not differ between the two methods.

Adult↗
PubMed1979

[Thallium 201 myocardial scintigraphy. Clinical use and value].

Thallium-201 exercise myocardial perfusion scintigraphy, a new, non-invasive screening method, serves to visualize stress-induced ischemic regions and scarred tissue. As compared to the exercise electrocardiogram, the method shows higher sensitivity and specificity in detecting coronary artery disease. Moreover, it makes it possible to localize the predominant defects. Even though myocardial scintigraphy cannot replace coronary arteriography in establishing the precise morphologic situation of the coronary arteries, it is of help in deciding whether an arteriogram should be carried out or not. Thus, important indications for myocardial stress scintigraphy are atypical chest pain and an abnormal electrocardiogram without pain. Furthermore, the method is useful for evaluating patients with uninterpretable electrocardiograms during exercise, and in assessing the outcome of coronary artery bypass surgery.

Coronary Artery Bypass↗
PubMed1978

[Nuclear medical determination of the ejection fraction and the regional wall movements of the left ventricle].

Left ventricular ejection fraction was determined in 114 patients by radionuclide and contrast angiocardiography. The correlation coefficient (r) amounted to 0.66. Exclusion of patients with arrhythmias and with a difference in heart rate exceeding 15 beats per minute between the two determinations of the ejection fraction increased r to 0.80 (61 patients). In patients with coronary artery disease and cardiomyopathies (n = 35), r was higher (0.88) than in patients (n = 26) with acquired valve disease or congenital heart disease (0.60). Comparison of first pass radionuclide angiocardiography and gated blood pool scanning with contrast angiocardiography in 19 patients elicited an r-value of 0.82 for the first pass method and of 0.31 for gated blood pool scanning. Visual assessment of local wall motion by gated blood pool scanning in 15 patients showed agreement with cineangiographically quantitated segmental motion (normo-, hypo- or a-kinesis) in 50 of 60 (= 83%) evaluated segments.

Angiocardiography↗
PubMed1977

The effect of mannitol following permanent coronary occlusion.

Quantitative comparisons of infarcts 24 hours after ligation of the left anterior descending coronary artery (LAD) via thoracotomy were made in 13 control and 13 dogs treated with i.v. 25% mannitol, 2 ml/min for 4 hours following occlusion. Mannitol increased serum osmolarity by 44+/-4 mOsm/L (mean +/- 1 SE) with hemodynamic effects limited to a small increase in left ventricular dP/dt. Nonperfusible tissue measured by planimetry at 24 hours was similar in both groups (46+/-4% of area defined with dye injected into the distal LAD for control versus 48+/-5% for mannitol treated dogs, P = NS). Creatine phosphokinase activity in infarcted tissues was also similar in both groups. Myocardial blood flows measured with radioactive microspheres were also similar in both groups. Collateral conductance calcultaed from retrograde flow and aortic pressure increased with the 24 hour period by 146+/-23% in the control dogs; in the mannitol treated dogs, collateral increased only 38+/-14% (P less than 0.001). Thus mannitol had no effect on ultimate infarct size. Moreover, mannitol appeared to hinder the development of collateral vessels.

Animals↗
PubMed1977

Absence of a lateral border zone of intermediate creatine phosphokinase depletion surrounding a central infarct 24 hours after acute coronary occlusion in the dog.

Myocardial creatine phosphokinase (CPK) activity was measured as an indicator of cell viability 24 hours after ligation of the left anterior sescending coronary artery (LAD) in normal myocardium, the entire region supplied by the LAD, and individual samples from the border and center of the infarct. Tissue supplied by the LAD and delineated by dye was carefully dissected from normal tissue along the stained border, CPK activity in the ischemic myocardium was calculated by assuming normal CPK activity in the ischemic myocardium was calculated by assuming normal CPK activity in normal myocardium interdigitating with ischemic tissue at the border. Normal tissue was marked prior to occlusion with microspheres injected into the left atrium, whereas the distal portion of the LAD was perfused separately with unlabeled blood from a reservoir. With this correction, the CPK activity in the ischemic tissue from the lateral border of the infarct was essentially the same as in samples from the center, whereas that in the normal tissue immediately adjacent to the stained border was equal to values in remote normal myocardium. Thus, CPK depletion throughout the entire ischemic myocardium was nearly equal to CPK depletion in the center of the infarct. The uncorrected intermediate CPK levels in the individual samples from the border of the stained region correlated with the amount of normal tissue contaminating these samples. However, differences in CPK depletion across the heart wall resulted in the most depletion in the subendocardium and the least in the epicardium. Further more, coronary collateral blood flow measured 10 minutes after occlusion correlated well with the subsequent extent of CPK depletion.

Animals↗
PubMed1976

Pulmonary angiotensin-converting enzyme. Interspecies homology and inhibition by heterologous antibody in vivo.

Goat antibody against pure rabbit pulmonary angiotensin-converting enzyme was used to probe homology of converting enzymes from other species. Immunologically cross-reactive material was found in detergent-solubilized extracts of lung particles from rat, guinea pig, and dog by double immunodiffusion, radioimmunoassay, and inhibition of enzyme activity. No homology was demonstrable with bovine, frog, or chicken lung extracts. Antibodies from different individual goats yielded comparable estimates of homology by immunodiffusion and radioimmunoassay. In contrast, they varied greatly in extent and specificity of their inhibitory action on heterologous enzyme activity. The vasopressor effect of angiotensin I and the vasodepressor effect of bradykinin were diminished and potentiated, respectively, in rats treated with anti-rabbit enzyme antibody. A smaller but significant immune-dependent inhibition of the vasopressor response to angiotensin II was also observed.

Angiotensin II↗
PubMed1976

Redistribution of collateral blood flow from necrotic to surviving myocardium following coronary occlusion in the dog.

Early changes in collateral blood flow after acute coronary occlusion may be critical for survival of ischemic myocardium. We used 15-mum radioactive microspheres to study myocardial blood flow in thoracotomized dogs 10 minutes and 24 hours after occlusion of the left anterior descending coronary artery (LAD). The ischemic area was delineated by dye injected into the distal artery, and indentification of potentially ischemic samples was confirmed by a newly developed technique in which microspheres were excluded from the normally perfused LAD. Layers were separated into necrotic or normal as defined by gross inspection and confirmed by histological examination and creatine phosphokinase assay. Infarction always involved endocardial layers and extended toward the epicardium. Average myocardial blood flow in 48 necrotic samples from 16 dogs either remained low (less than 0.05 ml/min g-1) or declined, falling from 0.11 +/-0.02(SE) at 10 minutes to 0.05 +/-0.01 ml/min g-1 at 24 hours (P less than 0.001). In contrast, in the 32 normal-appearing samples which were ischemic at 10 minutes, flow increased from 0.24 +/-0.03 to 0.39 +/-0.04 ml/min g-1 (P less than 0.001). Flow in control myocardium was 1.43 +/-0.12 and 1.04 +/-0.07 ml/min g-1, respectively. Peripheral mean coronary arterial pressure increased from 26 +/- 3 to 35 +/- 3 mm Hg, largely because of enlargement of collateral vessels; collateral conductance calculated from retrograde flow in 14 dogs increased from 0.023 +/- 0.005 after occlusion to 0.051 +/- 0.009 ml/min mm Hg-1 24 hours later (P less than 0.001). Thus, coronary collateral blood flow is redistributed from necrotic endocardial layers to surviving epicardial ones. In combination with a developing collateral supply this process may be essential for sparing myocardium after coronary occlusion.

Animals↗