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Biomedical subjects

L M Zir

Publications and source records attributed to L M Zir.

At least 19 recordsLinked to original sources
PubMed1979

Effects of coronary bypass grafting on resting left ventricular contraction in patients studied 1 to 2 years after operation.

Left ventricular contraction was evaluated with angiography in 51 patients 1 to 2 years after coronary arterial bypass surgery. The left ventricle was classified into five segments, and segmental ventricular wall motion was analyzed with subjective and objective methods. With subjective analysis, 25 percent of asynergic segments showed improvement, 72 percent no change and 3 percent deterioration in contraction. There was a 5 percent incidence rate of new wall motion abnormalities in segments that were judged normal from the preoperative ventriculogram. Objective analysis revealed significant improvement in contraction of asynergic segments in each of the five left ventricular segments analyzed. Thus, 1 to 2 years after coronary bypass surgery, there was a significant reduction in left ventricular segmental wall motion abnormalities, and the incidence of deterioration in contraction was small.

Coronary Artery Bypass↗
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↗
PubMed1978

The risk of advanced heart block in surgical patients with right bundle branch block and left axis deviation.

The risk of advanced atrioventricular block during anesthesia was studied prosepctively in 44 patients with right bundle branch block and left axis deviation who underwent a total of 52 operations over a 14 month period. All patients had continuous electrocardiographic monitoring throughout anesthesia induction, operation, and surgical recovery. Of the 52 operative procedures, 24 were done under general anesthesia, 11 under spinal, and 17 under local. The preoperative cardiac rhythms were atrial fibrillation in two patients, atrial tachycardia with block in one patient, atrial flutter in one patient, and sinus rhythm in the remaining patients. Temporary pacemakers were inserted preoperatively in six patients, usually because of PR interval prolongation on the preoperative electrocardiogram. There was only one episode of transient complete heart block in 51 of the 52 operative procedures. In two of the six patients with temporary pacemakers, significant pacer-related ventricular irritability occurred. This study indicates that temporary pacemaker insertion is rarely required in patients with chronic right bundle branch block and left axis deviation who require noncardiac surgery.

Adult↗
PubMed1977

Relation between phasic mitral flow and the echocardiogram of the mitral valve in man.

Ten patients without valvular disease were studied by ventriculography, and the rate and pattern of phasic blood flow into the left ventricle were determined by ventricular volume determinations at intervals of 33 ms during a single diastolic filling period. The derived left ventricular inflow patterns were then compared with the echocardiographic mitral EF slope obtained no more than 25 minutes before left ventriculography. The steepness of the EF slope was found to be inversely correlated with the time required to reach peak inflow velocity (r = 0.80, P less than 0.01) and directly correlated with the peak left ventricular inflow velocity divided by the time required to reach peak velocity (r = 0.72, P less than 0.05). No correlation was found between mean flow velocity into the left ventricle and the EF slope (r = 0.40, P = NS). A significant inverse correlation was found between the EF slope and the fraction of the diastolic filling period elapsed when 50 per cent of the filling volume had entered the left ventricle (r = 0.85, P less than 0.01). These findings suggest that the time required to reach left ventricular peak inflow velocity is one of the determinants of the mitral EF slope.

Angiocardiography↗
PubMed1977

Total anomalous pulmonary venous connection and severe pulmonic stenosis in a 52-year-old man.

Total anomalous pulmonary venous connection (TAPVC) is a rare cardiac congenital abnormality which usually results in death in infancy or early childhood. We describe a 52-year-old man with TAPVC and severe calcific pulmonic stenosis. Both diagnoses were suspected clinically and from the chest X-ray. Cardiac catheterization was confirmatory, and the patient underwent surgery. His initial postoperative course has been unremarkable. The hemodynamic factors relevant to long survival and relative freedom from symptoms in TAPVC are considered based on findings in this patient.

Heart Defects, Congenital↗
PubMed1977

Differentiation of transiently ischemic from infarcted myocardium by serial imaging after a single dose of thallium-201.

Myocardial 201Tl uptake and regional blood flow by the microsphere technique were determined in anesthetized dogs undergoing either 20 min of coronary occlusion and 100 min of reperfusion (N = 10) or 120 min of occlusion (N = 4). In both groups, 201Tl was injected intravenously after 10 min of occlusion. In transiently occluded dogs, regional flow at the time of 201Tl administration was reduced to 8 +/- 3% of normal flow in endocardial layers of the central ischemic zone. After 100 min of reperfusion, flow values were not significantly different from normal. 201Tl activity after reperfusion rose to 56 +/- 5% of normal, demonstrating that redistribution of the radionuclide occurred during the reflow period. In animals with persistent occlusion, there was a significant relationship between 201Tl uptake and flow (r = 0.95) and no evidence of redistribution of 201Tl during the two hour occlusion period. In another five dogs receiving 201Tl, serial gamma camera images obtained during reperfusion showed increasing uptake of the tracer in apical defects which returned to normal by 4 hours of reflow. Thirteen patients with stable angina received 2 mCi of 201Tl intravenously at peak exercise, and multiple gamma camera images obtained serially. All demonstrated zones of diminished 201Tl uptake 10 min after exercise. Defects which partially or completely disappeared within 1-6 hours postexercise corresponded to areas supplied by coronary arteries with significant stenoses. Persistent defects were present in regions of old myocardial infarction. Six additional patients with acute myocardial infarction demonstrated 201Tl myocardial defects which showed no significant change over 6 hours. Thus, redistribution of 201Tl into ischemic myocardium was demonstrated during transient coronary occlusion in dogs and after exercise stress in man. Sequential imaging after a single dose of 201Tl at the time of exercise may provide a means for distinguishing between transient perfusion abnormalities or ischemia and myocardial infarction of scar.

Acute Disease↗
PubMed1976

Effects of intravenous glucose during pacing-induced angina pectoris in patients with coronary artery disease.

The effects of hypertonic glucose infusion on the anginal threshold determined by atrial pacing was studied in 14 patients with significant coronary artery disease. After glucose, angina occurred at a significantly lower heart rate and double product (systolic arterial pressure x heart rate), suggesting a decreased tolerance to ischemic stress. No stoichiometric relationship was noted between glucose uptake and lactate production, and there was no evidence that hypertonic glucose infusion resulted in enhanced anaerobic glycolysis in the ischemic myocardium. Acute elevation of plasma glucose levels may not be beneficial to patients with coronary artery disease.

Anaerobiosis↗
PubMed1976

Interobserver variability in coronary angiography.

Four experienced coronary angiographers (two radiologists and two cardiologists) independently assessed the location and degree of coronary artery stenosis, and the location and degree of left ventricular wall motion abnormalities in 20 coronary angiograms. Marked interobserver variability was noted in quantifying percent coronary artery stenosis and degree of left ventricular wall motion abnormalities. For example, in only 13/20 (65%) of the coronary angiograms did all observers agree about the significance of a stenosis (defined as greater than 50% in diameter luminal narrowing) in the proximal or mid left anterior descending coronary artery. In 3/20 (15%) angiograms there was disagreement by at least one observer about the significance of lesions noted in the main left coronary artery. The ventricle was divided into five segments and the degree of wall motion abnormality graded into six categories of increasing severity from normal to dyskinesis. There was a 42% mean disagreement among all four observers where a disagreement between observers was defined as any difference in grading wall motion abnormalities. Interobserver variability reveals a significant limitation of coronary angiography.

Angiography↗
PubMed1975

Experience with preformed catheters for coronary angiography by the brachial approach.

Experience with a simplified technique for selective coronary angiography by the brachial cutdown approach using preformed coronary catheters in over 500 cases is described. This technique has facilitated selective catheterization of the coronary arteries in patients where use of the Sones catheter has proven difficult or impossible. Particularly, coronary arteries in patients with a dilated aortic root, high-rising left coronary artery or tortuous subclavian artery are easily catheterized with the preformed catheters described in this report. Shortened procedure time, an acceptable morbidity (1.4%) and mortality (0.2%), and improved coronary opacification by virtue of the ease in selectively entering the coronary ostia make these preformed catheters a useful modification to coronary angiography by the transbrachial approach.

Angiography↗
PubMed1975

Left ventricular wall motion response to intravenous propranolol.

The effects of intravenous propranolol on left ventricular wall motion and hemodynamics were studied in 16 patients, 12 with significant coronary artery disease and four with chest pain but no coronary disease. Eight patients received 0.10 mg/kg and eight received 0.15 mg/kg of propranolol intravenously. All underwent atrial pacing at a constant rate. Left ventricular angiograms were performed before and 20 minutes after propranolol. At both doses, propranolol caused no significant change in left ventricular systolic or diastolic pressures, either before or immediately following ventriculography. Cardiac index fell significantly (3.4 plus or minus 0.2 [SEM] to 2.6 plus or minus 0.1 L/min/m-2) with the higher dose only. Of the ten patients with coronary artery disease and adequate ventriculograms, one patient had a normal left ventricle, two had regional hypokinesis, only three had areas of hypokinesis and akinesis, two had dyskinetic and akinetic areas, and two had areas of hypokinesis, akinesis and dyskinesis. No changes in regional contractility occurred with propranolol except for a minimal increase in hypokinesis in one patient at each dosage and equivocal development of a new area of slight hypokinesis in one patient and minimal apex of dyskinesis in another at the higher dosage. Of the four patients without coronary artery disease, two were affected by propranolol, one with initial regional akinesis and dyskinesis had slight worsening with propranolol and one with regional hypokinesis developed a definite new area of hypokinesis. Therefore, propranolol, even in large intravenous doses, resulted in no significant change in left ventricular wall motion in patients with coronary artery disease.

1-Propanol↗
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↗
PubMed1975

Diagnostic uses of electrical pacing.

Diagnostic pacing has proven useful for the study of a great variety of clinical problems. Rapid atrial pacing is an excellent means of stressing the heart, particularly in patients with ischemic heart disease. Pacing-induced tachycardia has been used to provoke typical coronary pain and to produce hemodynamic, metabolic, and left ventricular contractile changes in patients with coronary artery disease. Because this heart stress is reproducible, it has also been valuable in assessing response to medical and surgic al therapy in patients with angina. Electrophysiologically, pacing has been used to clarify mechanisms of normal and abnormal function of the sinus node and A-V conduction. The pre-excitation states have been more precisely defined, and the introduction of programmed electrical stimuli into the cardiac cycle has helped elucidate the nature of re-entry supraventricular tachycardias.

Arrhythmia, Sinus↗