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Biomedical subjects

K Chatterjee

Publications and source records attributed to K Chatterjee.

At least 271 records · Page 15Linked to original sources
PubMed1976

Acute changes in the diastolic pressure-volume relationship of the left ventricle.

Acute changes in the diastolic pressure-volume relationship of the left ventricle. Europ. J. Cardiol., 4/Suppl., 105-120. The present study was designed to investigate acute changes in the passive length-tension relations of isolated heart muscle and acute alterations of the left ventricular diastolic pressure-volume relationship of patients. In isolated heart muscle a constant lengthening and shortening technique with computer curve fitting was used to characterize the entire passive length-tension relation. There was no change in passive elastivity following an increase in stimulation frequency or an increase in muscle stretching rate. During the transition from stimulated to nonstimulated contractions, there was a shift to the left in the passive length-tension relation, with a shorter muscle length at the same resting force. In 10 patients undergoing revascularization for preinfarction angina, 7 patients showed a significantly reduced left ventricular enddiastolic pressure at the same enddiastolic volume, together with an improvement in postoperative ejection fraction. In 6 patients who experienced a perioperative myocardial infarction, variable changes in the pressure volume relationship occurred. These presumably reflected the opposite effects of stiffening of infarcted muscle and cardiac dilatation secondary to heart failure. 26 patients with chronic coronary artery disease had ventriculograms before and after 0.4 mg sublingual nitroglycerin. 9 patients showed a significant shift downwards in their pressure-volume relation, with a decreased enddiastolic pressure at the same volume. 2 showed a shift upwards, while the remaining patients showed no measurable change. It is proposed that this latter shift in pressure-volume relationships is due to hemodynamic factors rather than to intrinsic changes in muscle stiffness. Theoretical calculations utilizing A SIMPLIFIED SPHERICAL MODEL of the ventricle suggest that the magnitude of the changes observed cannot be explained by stiffening of the muscle alone and is therefore probably due to hemodynamic factors.

Cardiac Output↗
PubMed1975

Hemodynamic and metabolic effects of isosorbide dinitrate in chronic congestive heart failure.

To assess the potential beneficial effects of a nonparenteral vasodilator, sublingual isosorbide dinitrate (5 to 15 mg.) was administered in 12 patients with chronic congestive heart failure refractory to conventional therapy. Hemodynamic measurements were performed before and at 15 minute intervals after drug administration for 90 minutes. Venous capacitance was measured at 5 minute intervals. Myocardial metabolism was also studied in five patients before and after drug administration. Hemodynamic effects were characterized by a modest decrease in mean arterial pressure (85 +/- 3 to 78 +/- 2 [S.E.M.] mm. Hg) and substantial decrease in right atrial (10 +/- 1 to 6 +/- 1), pulmonary arterial (39 +/- 4 to 30 +/- 4) and pulmonary capillary wedge pressures (28 +/- 2 to 21 +h- 2). These changes were accompanied by an increase in venous capacitance (2.46 +/- 0.16 to 3.99 +/- 0.24 c.c./100 c.c. of tissue). Along with a decrease in left ventricular filling pressure, cardiac index increased (1.99 +/- 0.13 to 2.37 +/- 0.15 L./min/M.2). No significant effect on heart rate was seen. Delta P/delta t, an index related to left ventricular dp/dt, increased in all but one patient (253 +/- 31 to 298 +/- 39 mm. Hg/sec.) (p less than 0.02 for all changes) in the face of decreased preload and afterload and unchanged heart rate, suggesting improved contractile state. A decrease in coronary blood flow (165 +/- 13 to 131 +/- 15 c.c./min.) and myocardial oxygen consumption (18.1 +/- 1.6 to 14.5 +/- 1.6 c.c./min.) was noted (p less than 0.02). No change in arterial-coronary sinus oxygen difference or lactate extraction was observed. These data demonstrate that the objectives of therapy in congestive heart failure, namely improved forward output and decreased ventricular filling pressures, can be achieved without metabolic deterioration by using sublingual isosorbide. The mechanisms responsible are related to diminished impedence to ventricular ejection and peripheral pooling of blood. Since the duration of action does not usually exceed 90 minutes, frequent drug administration may be a source of patient inconvience.

Administration, Oral↗
PubMed1975

Use of a balloon-tipped flotation electrode catheter for cardiac mounting.

A new balloon-tipped flotation catheter equipped with two pairs of electrodes has been developed for simultaneous monitoring of cardiac rhythm and hemodynamics as well as for temporary emergency atrial, ventricular and atrioventricular sequential pacing. Experience in 43 patients demonstrates the following: (1) The catheter can be passed and positioned with the tip in the pulmonary artery or its branches at the bedside with the use of fluoroscopy as easily as the standard (Swan-Ganz) catheters. (2) With the catheter in the proper position ans with the use of appropriate filters (proximal, 50 to 300 hertz; distal, 15 to 300 hertz), the intracavity electrograms recorded from the proximal and distal pair of electrodes provide characteristic high right atrial and right ventricular signals, virtually free of noise artifact, baseline drift and respiratory variation, that are particularly suitable for automated on-line monitoring of cardiac rhythm. (3) When indicated, atrial, ventricular or atrioventricular sequential pacing can be initiated without delay. (4) Large artifact-free right ventricular intracavitary signals can be used for reliable and consistent operation of any device requiring QRS triggering mechanisms. (5) Monitoring of pulmonary arterial or pulmonary capillary wedge pressure and withdrawal of blood samples from the central circulation is possible. This device can be particularly useful in patients with hemodynamic difficulties as well as arrhythmias.

Arrhythmias, Cardiac↗
PubMed1975

Abnormal regional metabolism and mechanical function in patients with ischemic heart diseases: improvement after successful regional revascularization by aortocoronary bypass.

Left ventricular anterior wall metabolism was investigated concurrently with global myocardail metabolism by simultaneous preoperation sampling of anterior interventricular venous (AIV) and coronary sinus (CS) as well as arterial bloods in seven patients with severe obstructive lesions of the major coronary arteries, including left anterior descending. Postoperative study was performed two weeks to six months following successful aortocoronary artery bypass surgery. All grafts including the aorto-left anterior descending artery grafts were patent. Preoperatively in three of the seven patients, anterior wall lactate extraction (R%L) was negative at rest. The average R%L at rest (7 +/- 14%) was abnormal and was negative (-49 +/- 26%) at a maximum supraventricular pacing rate (MPR) of 137 +/- 4.6 beats/min. Postoperatively, not only was resting R%L (39 +/- 4;4%) normal but also it remained normal during atrial pacing (32 +/- 8.5%) even though the postoperative MPR (164 +/- 4.4 beats/min) was much higher than the preoperative MPR; Postoperatively AIV pO2 both at rest (21 +/- 1.1 mm Hg) and at MPR (22 +/- 1.3 mm Hg) and directly determined O2 saturations (resting: 34 +/- 3.0%; MPR:35 +/- 2.1%) tended to be higher than the preoperative values (AIV pO2, resting: 18 +/- 1.7; MPR: 19 +/- 1.7 mm Hg; AIV O2 saturation resting: 30 +/- 2.7; MPR: 33 +/- 3.3%), although only differences in pO2 were statistically significant. In five of the seven patients in whom the pre and postoperative left ventricular angiograms could be compared, systolic wall motion of the left ventricular anterior wall improved markedly postoperatively. Average global myocardial lactate extraction (G%L) preoperatively was normal (19 +/- 4.8%) at rest but was negative (-22 +/- 12%) at MPR. Postoperatively however, G%L both at rest (44 +/- 5.5%) and at MPR (34 +/- 7.9%) were normal. Coronary sinus pO2 and O2 saturation were also higher postoperatively compared to the preoperative values. Over-all left ventricular performance indicated by increase in ejection fraction also improved postoperatively. This improvement was not caused by increased coronary blood flow. Postoperative coronary sinus blood flow both at rest (114 +/- 19 ml/min) and at MPR (199 +/- 27 ml/min) however were less than the preoperative values (resting 136 +/- 24, MPR 261 +/- 40 ml/min), There was also no increase in global O2 delivery and O2 consumption despite higher heart rate and rate-pressure product achieved during postoperative pacing stress and the patients did not develop angina. These findings suggest that improved regional and global metabolism and mechanical functions observed postoperatively in these patients may be due to redistribution of blood flow to the ischemic and nonischemic myocardium following successful aortocoronary artery bypass surgery.

Adult↗
PubMed1975

The rationale for surgery in preinfarction angina.

Of 123 patients with identical clinical criteria for preinfarction angina, 35 were treated medically and 88 surgically in a nonrandomized manner. There was no statistical difference between these two therapeutic groups in regard to age range, average age, sex distribution, number and distribution of prior myocardial infarction, and duration of chronic and acute anginal symptoms. With medical therapy, 32 sustained a myocardial infarction, and 14 (40 per cent) of these died within 1 month of hospital admission. Thirteen of 21 survivors or 37 per cent of the original group are asmptomatic on continuing medical therapy an average of 15 months after discharge. The surgical patients were studied by catherization and anigiography and underwent an early operation. Eight (9.4 per cent) demonstrated evidence of postoperative infarction, and 3 (3.4 per cent) died after the operation. Seventy-one (84 per cent) are completely asymptomatic and 6 are less symptomatic an average of 17 months after the operation. Actuarial analysis of the follow-up data reveals that the initial significant difference in survival between the two groups is maintained through the first 36 months. On the basis of this experience, we suggest that surgical intervention is the therapy of choice in patients with preinfarction angina.

Adult↗
PubMed1975

Improved angina threshold and coronary reserve following direct myocardial revascularization.

Angina threshold, coronary reserve, and global myocardial lactate metabolism were studied by atrial pacing in 18 patients with obstructive coronary artery disease before and after aortocoronary artery bypass (ACB) surgery. In 3 of these 18 patients, regional (anterior wall) metabolism was also studied. Following ACB, 16 of the 18 patients did not develop angina at the maximum pacing rate (MPR). One patient developed angina postoperatively at a similar rate as before surgery. In the other patient, postoperative angina threshold was much higher. In the group as a whole, postoperative MPR (159 +/- 3.5 beats/min) was much higher than the preoperative angina rate (124.9 +/- 4.9 beats/min; P less than 0.001). Rate-pressure product (RP) at MPR postoperatively (21.5 +/- 0.89 mm Hg/min X 10(-3)) was also higher than RP at angina rate preoperatively (18.8 +/- 0.92 mm Hg/min X 10(-3); P less than 0.01). Although coronary sinus blood flow (CSBF) both at rest (152 +/- 16.2 ml/min) and at MRP (266 +/- 27.5 ml/min) postoperatively was higher than preoperative CSBF at rest (111 +/- 10.7 ml/min; P less than 0.05) and at angina rate (202 +/- 19.9 ml/min; P less than 0.05), arterial-coronary sinus O2 content (Art.-CSO2) difference was significantly lower postoperatively both at rest (8.9 +/- 0.37 ml/min) and at MPR (9.1 +/- 0.44 ml/min) compared with the preoperative Art.-CSO2 at the rest (12.7 +/- 0.40 ml/min; P less than 0.01) and at angina rate (12.4 +/- 3.8 ml/min; P less than 0.01)...

Adult↗