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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The possible advantages of pulsatile over continuous blood flow have intrigued cardiac surgeons for years. This issue may have clinical significance for moderate to long cardiopulmonary bypass procedures. In spite of aggressive investigation, this problem remains controversial. A system permitting perfusion of an isolated canine hind limb with constant flow, Pao2, Paco2, oxygen delivery, temperature, and pHa but variable stroke volume was established. Under stable conditions, oxygen uptake by the limb was constant over a wide range of stroke volumes. Regression equations relating oxygen uptake to stroke volume were calculated and found to have a near zero slope. When the hydrogen ion concentration of the blood perfusing tissue is held constant, the oxygen consumption of that tissue is independent of the pulsatile nature of the perfusing blood.
J Thorac Cardiovasc Surg 1975 Aug
PMID:The influence of pulsatile perfusion on oxygen uptake by the isolated canine hind limb. 23 95

The hemodynamic effects of vasodilator treatment (afterload reduction) with nitroprusside at a constant heart rate were studied in 24 patients early after aorta-coronary bypass grafting. In 12 patients, dose-response relationships were determined. Graded incremental infusions of nitroprusside produced progressive decreases in mean arterial pressure (MAP), right and left atrial pressures, and stroke work index. Stroke volume index and cardiac index rose significantly until MAP was reduced below the range of 80 to 90 mm. Hg, and then they fell to base-line levels owing to insufficient preload. In an additional 12 patients, MAP was reduced with nitroprusside to the range of 80 to 90 mm. Hg, and left atrial pressure was then restored to base-line levels during continued vasodilator administration. This sequence resulted in further augmentation of stroke volume index to a level higher than that produced by nitroprusside alone. We conclude from this investigation that nitroprusside is a clinically useful agent for primary or adjunctive therapy of mild-to-moderate low cardiac output states immediate postoperatively and that simultaneous regulation of left ventricular preload and after load during its administration is necessary in order to achieve maximal hemodynamic benefit.
J Thorac Cardiovasc Surg 1977 Apr
PMID:Control of myocardial performance early after open-heart operations by vasodilator treatment. 30 Jan 33

The study includes 50 patients with severe, stable angina who have undergone the saphenous vein bypass operation. Patients were evaluated preoperatively and postoperatively with regard to exercise tolerance, incidence of stress-induced agina, ST-segment changes of ischemia, and ventricular function as indicated by stroke work index (LVSWI) and ejection fraction. Comparisons were made between patients with complete revascularization (CR) and patients with postoperative residual ischemia (RI). Results revealed that exercise duration improved significantly in both the CR and RI groups. In the CR group, angina and ischemic ST changes were completely eliminated. In the RI group, there was a 25 percent incidence of stress angina and a 50 percent incidence of ischemic ST-segment changes. In neither group was the ejection fraction significantly different from preoperative values. LVSWI decreased significantly in both groups postoperatively.
J Thorac Cardiovasc Surg 1977 Jul
PMID:Evaluation of saphenous vein bypass surgery with multistage treadmill test and ventricular function studies. 30 89

Three patients with angina pectoris were studied before and after aortocoronary bypass surgery. Angiographic studies were performed with and without atrial pacing. Preoperative atrial pacing in all three patients resulted in angina and/or ST segment changes accompanied by regional left ventricular contractile abnormalities, decreased ejection fraction, as well as decreased left ventricular end-diastolic and stroke volumes. After surgery with all grafts patent, atrial pacing at similar heart rates did not produce an ischemic response. Left ventricular contractile pattern remained normal, and there was no change in ejection fraction though end-diastolic and stroke volumes decreased. These studies demonstrate that aortocoronary bypass surgery can abolish both the ischemic response and left ventricular dysfunction that accompany atrial pacing.
Cathet Cardiovasc Diagn 1979
PMID:Atrial pacing induced left ventricular dysfunction: reversibility after aortocoronary bypass surgery. 31 53

We have compared indices of ventricular function during rapid transfusion of citrated (1.5 ml/kg/min) or heparinized (1.5 ml/kg/min) autologous blood in six patients following discontinuation of cardiopulmonary bypass. Infusion of citrated blood was associated with a lowering of plasma ionized calcium concentration ([Ca++], from 0.90 +/- 0.04 to 0.71 +/- 0.4 mM, p less than 0.001) and an increase in pulmonary artery balloon-occluded pressure (PA0, from 9.4 +/- 2.6 to 15.5 +/- 1.7 mm Hg, p less than 0.u1), without a change in left ventricular stroke work index, stroke index, or cardiac index. Transfusion of heparinized blood caused no change in plasma [Ca++]. A rise in PA0, which was similar in magnitude to that observed during citrated blood transfusion, was associated with increased left ventricular stroke work index, stroke index, cardiac index, and mean arterial pressure. Although data obtained during citrated blood transfusion suggest the presence of transient left ventricular dysfunction, its magnitude is not readily expressed in terms of ventricular function curves when accompanied by a simultaneous change in [Cized closed-chest dog by volume loading during hypocalcemia, when mean arterial pressure, heart rate, and [Ca++] were in a steady state, both prior to and following beta blockade with propranolol. Function curves obtained during severe hypocalcemia ([Ca++] = 0.43 +/- 0.02 mM) were shifted significantly to the right and downward, when compared to those obtained during normocalcemia ([Ca++] = 1.06 +/- 0.03 mM). Hypocalcemia combined with beta blockade resulted in severe left ventricular failure, as demonstrated by a flat ventricular function curve.
J Thorac Cardiovasc Surg 1979 Aug
PMID:Ventricular pump performance during hypocalcemia: clinical and experimental studies. 31 87

Immediately after mitral commissurotomy, we measured pulmonary blood volume by dye-dilution method and investigated the relationships between pulmonary blood volume and other hemodynamic parameters. Pulmonary blood volume correlated directly to pulmonary mean transit time, cardiac index, stroke volume index, and mean left atrial pressure. Pulmonary blood volume increased with mean pulmonary arterial pressures up to 35 mm. Hg but decreased with elevation above this level. The same patterns were observed in the correlations between pulmonary blood volume and both pulmonary distending pressure and pulmonary vascular resistance. These observations suggest that the changes of the pulmonary vessels begin with the elevation of mean pulmonary arterial pressure above 35 mm. Hg, pulmonary distending pressure above 25 mm. Hg or pulmonary vascular resistance above 5 units. Therefore, it is desirable to maintain mean pulmonary arterial pressure below 35 mm. Hg in patients immediately after mitral commissurotomy.
J Thorac Cardiovasc Surg 1977 Apr
PMID:Pulmonary blood volume and its significance in pulmonary hemodynamics immediately after mitral commissurotomy. 32 Apr 1

Using radioactive microspheres, we studied the quantitative and sequential distribution of myocardial blood flow during acute rejection of cardiac orthotopic allografts in 15 nonimmunosuppressed dogs. During rejection mean cardiac output per kilogram decreased 49 percent from control, stroke volume per kilogram decreased 40 percent, total left ventricular flow decreased 43 percent, and the subendocardial/subepicardial flow ratio (I/O) of the left ventricular free wall decreased 21 percent. Relative subendocardial hypoperfusion occurred despite an increase in the ratio of left ventricle subendocardial supply (diastolic pressure-time index) to demand (tension-time index). The data indicate that total left ventricular flow decreases severely and selective left ventricular subendocardial ischemia develops very early during acute cardiac rejection.
J Thorac Cardiovasc Surg 1978 Apr
PMID:Alterations in total and regional myocardial blood flow during acute rejection of orthotopic canine cardiac allografts. 34 80

Experiments to assess left ventricular function in dogs during and after 2 hours of hypothermic cardioplegia are reported. During the experiment myocardial temperature was maintained between 15 degrees C and 18 degrees C by controlling the rate of flow of a cool cardioplegic solution into the coronary vessels. Before and after the period of hypothermia the left atrial pressure was gradually changed and the aortic flows and pressures that changed in response were recorded. The left ventricular stroke work (gm) was then calculated using the relationship: LVSM = (formula: see text) where: SV = stroke volume (ml), AP = arterial pressure (mmHg), LAP = left atrial pressure (mmHg). Comparison of the calculated values indicated that this method of maintaining cardiac hypothermia reduced cardiac function only slightly.
J Cardiovasc Surg (Torino)
PMID:Coronary perfusion under general and selective cardiac hypothermia. 42 58

To compare the hemodynamic effect of vasodilator therapy on different regurgitant lesions, we infused sodium nitroprusside intraooperatively in 12 patients with mitral regurgitation and 15 with aortic regurgitation. During the critical period preceding establishment of cardiopulmonary bypass, both groups had developed intense vasoconstriction and cardiac decompensation. All demonstrated improved cardiac function with vasodilator therapy; however, the degree of improvement with nitroprusside differed in the two groups. Stroke volume increased 10 ml. per beat per meter squared in those patients with aortic regurgitation and only 6 ml. per beat per meter squared in those with mitral regurgitation (p less than 0.05). The percent increase in stoke volume induced by nitroprusside was inversely correlated to the preoperative left ventricular ejection fraction (r = 0.44, p less than 0.02). Patients with aortic regurgitation had lower preoperative left ventricular ejection fractions than those with mitral regurgitation (0.53 versus 0.63, p less than 0.02). Therefore, we conclude that patients with aortic regurgitation derived greater intraoperative hemodynamic benefit from unloading with nitroprusside, because they came to surgery with greater impairment of left ventricular contractility. Although nitroprusside improved cardiac function in both groups, only the patients with aortic regurgitation achieved normal pulmonary artery pressure (17 torr) and pulmonary vascular resistance (2.1 units) as a result of unloading. Those with mitral regurgitation continued to have pulmonary hypertension (28 torr) and increased pulmonary vascular resistance (3.9 units) despite vasodilator therapy. Thus the data suggest that patients with mitral regurgitation derived less hemodynamic benefit from intraoperative nitroprusside therapy because they were also limited by right ventricular dysfunction and a less responsive pulmonary vasculature.
J Thorac Cardiovasc Surg 1979 Jul
PMID:Comparison of intraoperative nitroprusside unloading in mitral and aortic regurgitation. 44 73

The future of cerebral vascular disease management depends upon a sound biochemical and physiological understanding of the processes leading to stroke. As these become defined, new forms of therapy will arise with greater promise for treatment of the constellation of factors and symptoms known as stroke.
Cardiovasc Res Cent Bull
PMID:Stroke--1978. 45 38


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