Contractility and energetics effects of ethanol and isoproterenol using an improved biologically stable isolated ejecting rat heart system.
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Adenosine Triphosphate↗
Biomedical subjects
D T Mason
Publications and source records attributed to D T Mason.
Afterload reduction therapy with nitroprusside in severe aortic regurgitation: improved cardiac performance and reduced regurgitant volume.
To assess the hemodynamic effects of afterload reduction in severe aortic regurgitation, nitroprusside was infused at cardiac catheterization in 12 patients with aortic regurgitation. Cardiac hemodynamics, angiographic variables and regurgitant volumes were quantified during control periods, and nitroprusside was infused to reduce systemic systolic pressure to 110 to 125 mm Hg. The following were reduced by the drug: systolic arterial pressure (from 154 +/- 6.4 to 115 +/- 2.3 mm Hg, P less than 0.001); left ventricular end-diastolic pressure (from 23 +/- 2.2 to 11 +/- 1.0 mm Hg, P less than 0.001); systemic vascular resistance (from 1,782 +/- 133 to 1,148 +/- 94 dynes sec cm-5, P less than 0.001); left ventricular end-diastolic volume (from 242 +/- 25 to 196 +/- 19 ml, P less than 0.001); aortic regurgitant fraction (from 0.53 +/- 0.05 to 0.44 +/- 0.06, P less than 0.01); and aortic regurgitant minute volume (from 5.5 +/- 0.10 to 4.3 +/- 0.09 liters/min, P less than 0.01). Effective cardiac index increased (from 2.49 +/- 0.19 to 3.10 +/- 0.24 liters/min per m2, P less than 0.01), and left ventricular ejection fraction rose (from 0.55 +/- 0.03 to 0.61 +/- 0.03, P less than 0.005). These data indicate that afterload reduction with nitroprusside in severe aortic regurgitation improves cardiac performance, greatly decreases left ventricular preload and reduces aortic regurgitant volume. Thus, nitroprusside therapy has special value in severe aortic regurgitation that is of particular benefit in critical clinical conditions.
Aged↗
Pump dysfunction after myocardial infarction: importance of location, extent and pattern of abnormal left ventricular segmental contraction.
To delineate the relative effects on left ventricular function of the site, extent and nature of the abnormal left ventricular segmental contraction (dyssynergy) and thereby determine the mechanism by which anterior myocardial infarction results in greater depression of left ventricular performance than does inferior infarction, 43 patients with remote myocardial infarction of similar extent (average 38 percent of left ventricular systolic perimeter) and associated hypokinesia or dyskinesia confined to either the anterior or inferior wall were compared; 10 additional patients were evaluated who exhibited generalized dyssynergy (72 percent of left ventricular perimeter). When the pattern of dyssynergy and extent of infarction were similar, the location alone of dyssynergy did not influence variables of left ventricular function. However paradoxical outward systolic movement (dyskinesia) of the anterior or inferior wall resulted in greater depression (P less than 0.05) of measures of left ventricular performance than did diminished inward systolic motion (hypokinesia) associated with infarction of similar extent and location. All measures of left ventricular performance were considerably more depressed (P less than 0.05) in the 10 patients with generalized dyssynergy than in the 43 patients with localized dyssynergy. Thus, the location of infarction is not a unique determinant of left ventricular performance. Instead, the size of infarction is the principal characteristic of dyssynergy that impairs left ventricular function; the severity of the pattern of dyssynergy is significant but of lesser importance. It is therefore concluded that the greater reduction of left ventricular function in anterior than in inferior myocardial is largely the result of the more extensive area of necrosis rather than of the location of the infarction.
Adult↗
Functional significance of coronary collateral vessels in patients with acute myocardial infarction: relation to pump performance, cardiogenic shock and survival.
In 20 patients with acute myocardial infarction requiring emergency left heart catheterization and coronary arteriography, ventricular function and clinical course were related to collateral vessels supplying the infarcted area. The major coronary artery to the infarcted region was severely obstructed in all patients. Patients with adequate collateral vessels (Group I, no. = 6) and those with no or inadequate collateral channels (Group II, no. = 14) had similar findings with respect to age, site of infarction, prevalence of prior infarction and presence of multivessel disease. However, there were significant differences between Groups I and II in left ventricular end-diastolic pressure (13 versus 30 mm Hg), cardiac index (3.05 versus 2.04 liters/min per m2), stroke work index (45 versus 13 g-m/m2), ejection fraction (42 versus 20 percent) and area of dyssynergy (14 versus 47 percent). Moreover, in Group I all patients survived and none had cardiogenic shock, whereas in Group II 10 of 14 patients had shock and 8 of 14 died. The rapidity of vessel obstruction appeared to influence collateralization since infarction was preceded by angina pectoris more frequently in Group I than in Group II. These results indicate that well functioning anastomotic channels to the distal trunk of the blocked coronary artery may afford some protection of pump function and improve the prognosis in acute myocardial infarction.
Acute Disease↗
Probucol: a new cholesterol-lowering drug effective in patients with type II hyperlipoproteinemia.
Type II hyperlipoproteinemia or hyperbetalipoproteinemia (B-HLP), a condition with considerable atherogenic potential, is one of the most difficult lipid disorders requiring treatment. Since this abnormality responds minimally to dietary therapy alone, supplemental drug therapy is usually essential. Although the available bile-sequestering resins are effective in B-HLP, these substances are unpalatable and constipating. Since lifelong drug therapy is necessary as an adjunct to diet in the treatment of B-HLP, the ideal drug should be both effective and well tolerated. Probucol, a new cholesterol-lowering drug in tablet form without serious adverse effects, was evaluated in a 12-wk double-blind crossover trial in 11 patients with B-HLP whose serum cholesterol levels were in excess of 275 mg/dl. Probucol, in a dosage of 500 mg twice daily, produced a 10% or greater reduction in serum cholesterol levels in all 11 patients. Serum cholesterol was lowered (p less than 0.01) from 353 to 291 mg/dl in the entire group receiving probucol. There was no significant change (p greater than 0.1) in serum cholesterol (352 mg/dl) during placebo administration. These were no untoward drug effects during the study, and all patients maintained excellent complicance to the schedule of medication. These results indicate that probucol possesses considerable cholesterol-lowering activity and may be a promising new nontoxic therapeutic agent in type II hyperlipoproteinemia.
Cholesterol↗
Efficacy of cardioselective beta adrenergic blockade with intravenously administered tolamolol in the treatment of cardiac arrhythmias.
The efficacy of tolamolol, a cardioselective beta adrenergic blocking agent, was evaluated in the treatment of cardiac arrhythmias in 27 patients. Nineteen patients had supraventricular arrhythmias and eight had ventricular arrhythmias. Evaluation was by doulbe-blind randomized trial in 23 patients. Tolamolol was effective in reducing ventricular rate in 17 (85 percent) of 19 patients with supraventricular arrhythmias and resulted in conversion to sinus rhythm in 2 of the 17. The mean ventricular rate in 17 patients decreased from 135 to 102/min 10 minutes after initiation of administration of tolamolol and gradually decreased further to 93/min after 60 minutes. Reduction in ventricular rate was sustained for 2 hours of monitoring undergone by all patients and for 4 and 6 hours monitoring in two subgroups. Among the eight patients with ventricular ectopic beats, tolamolol reduced their frequency in four patients and had no effect in four. Six patients had chronic obstructive pulmonary disease and experienced no adverse clinical effects on respiratory function in association with administration to tolamolol. Untoward effects occurred in 10 patients, including hypotension in 3, 1 of whom required vasopressor therapy. Other side effects were sedation, nausea, dyspnea and warmth in the chest, all of which were mild and transient, requiring no treatment. Cardioselective beta adrenergic blockade with tolamolol was highly effective in controlling ventricular rate in supraventricular arrhythmias and reduced the frequency of ventricular ectopic beats in half of the small group of patients with this arrhythmia. It is particularly applicable in patients with obstructive pulmonary disease in whom cardiac beta adrenergic blockade is indicated. Hypotension is an important potential side effect.
Adrenergic beta-Antagonists↗
Mitral valve early diastolic closing velocity in the echocardiogram: relation to sequential diastolic flow and ventricular compliance.
Uncertainty exists regarding the determinants of mitral valve early diastolic closing velocity (E-F slope) in the echocardiogram. Accordingly, the mitral E-F slope, sequential atrioventricular flow in each third of diastole in the cineangiogram and an index of ventricular compliance (delta volume/delta pressure normalized by end-diastolic volume) were obtained in 10 normal subjects, 10 patients with coronary artery disease and marked dyssynergy and 9 patients with hypertrophic cardiomyopathy. The E-F slope of 103 +/- 20 mm/sec (mean +/- standard deviation) in normal subjects was greatly reduced in patients with coronary artery disease and hypertrophic cardiomyopathy (54 +/- 22 and 27 +/- 16 mm/sec, respectively, P less than 0.001). Transmitral flow of 52 +/- 25 cc during the initial third of diastole in normal subjects represented 48 +/- 10 percent of total flow and was diminished in patients with coronary artery disease and hypertrophic cardiomyopathy: 23 +/- 16 cc (25 +/- 24 percent) and 24 +/- 20 cc (20 +/- 11 percent), respectively (both P less than 0.001). The ventricular compliance index in normal subjects of 0.064 +/- 0.02 was also decreased identically in patients with coronary artery disease and hypertrophic cardiomyopathy: 0.029 (both P less than 0.001). The E-F slope was correlated with transmitral flow during the first third of diastole (r = 0.87) but was decreased to a slightly greater extent for any given reduction in flow in patients with hypertrophic cardiomyopathy than in patients with coronary artery disease. Although the E-F slope could not be related to compliance in individual patients, patients with an E-F slope of less than 75 mm/sec nearly always had diminished compliance. Thus, mitral E-F slope is primarily related to transmitral flow in the initial third of diastole. Reduced ventricular diastolic compliance usually results in diminished flow, and thus a decreased E-F slope, in patients with coronary artery disease or hypertrophic cardiomyopathy. The greater reduction in E-F slope for any decrement of flow in hypertrophic cardiomyopathy than in coronary disease may be due either to interference with vortex streaming or to alterations in the relation of the papillary muscles to the mitral valve induced by altered ventricular geometry; the finding indicates that factors in addition to flow may influence the E-F slope.
Adult↗
Reduction of S-T segment elevation with infusion of nitroprusside in patients with acute myocardial infarction.
The effect of infusion of sodium nitroprusside on S-T segment elevation was evaluated in 12 patients with acute anterior myocardial infarction. Precordial 35 lead S-T segment maps were obtained in each patient immediately before and 10 minutes after infusion of 53 mug/min (range 20 to 100 mug/min) of nitroprusside. The following measurements were made from each S-T map: sigmaST (total S-T elevation in all leads), NST (number of leads with S-T elevation greater than 1 mm) and ST (average (S-T elevation in leads with more than 1 mm elevation). After administration of mitroprusside, evidence of myocardial ischemic injury as assessed by S-T mapping decreased in association with reduction of the myocardial oxygen consumption index of pressure-time per minute. Group mean values diminished significantly for sigmaST (41.7 to 28.6 mm, P less than 0.001), NST (20.3 to 14.6, P less than 0.001) and ST (1.6 to 1.2 mm, P less than 0.005). Pressure-time per minute decreased from 2,690 to 2,372 mm Hg-sec/min (P less than 0.001). Because there was no significant relation (P less than 0.05) between reductions in S-T elevation and lower indexes of myocardial oxygen consumption, it is suggested that nitroprusside may possess a separate action of augmenting regional blood flow to ischemic myocardium. Evaluation with the precordial S-T mapping technique suggested that intravenous administration of nitroprusside was associated with evidence of reduced ventricular ischemic injury in patients with acute myocardial infarction. This effect appears to be related to reduction of myocardial oxygen demand by the peripheral cardiac unloading mechanisms of nitroprusside as well as to a possible direct action of the drug in improving regional blood flow to ischemic heart muscle.
Acute Disease↗
Comparative effects of morphine, meperidine and pentazocine on cardiocirculatory dynamics in patients with acute myocardial infarction.
The cardiocirculatory effects of the commonly used parenteral analgesics, morphine sulfate 15 mg, meperidine hydrochloride 100 mg and pentazocine 60 mg, each administered intravenously, were compared in 12 patients with acute myocardial infarction during cardiac catheterization and by echocardiogram. No untoward hemodynamic effects occurred following the administration of morphine or meperidine. In contrast, pentazocine produced significant (p less than 0.01 to less than 0.05) increases in systemic and pulmonary arterial pressures, left ventricular filling pressure, systemic vascular resistance, and systolic and diastolic dimensions; and decreases in left ventricular ejection fraction and mean velocity of circumferential fiber shortening. These deleterious actions of pentazocine appeared due to peripheral vasoconstriction and negative inotropic properties. Further, pentazocine-induced increases in left ventricular preload and afterload increased myocardial oxygen demands. Since this study demonstrates that pentazocine is hazardous in myocardial infarction, morphine and meperidine are the preferred analgesics in this condition.
Adult↗
Effects of severe hemodynamic pressure overload on the properties of canine left ventricular myosin: mechanism by which myosin ATPase activity is lowered during chronic increased hemodynamic stress.
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Adenosine Triphosphatases↗
Purification of canine plasma renin by affinity chromatography.
An affinity column for the purfication of canine plasma renin was prepared using goat anti-renin (dog kidney) gammaG gloublins. The antiserum was prepared against a purified kidney renin preparation. The anti-renin globulins were coupled to cyanogen bromide activated Sepharose. Using the anti-renin globulin-coupled Sepharose as an immuno-adsorbant, a method was devised allowing purification of plasma renin to a 1,000-fold purity.
Animals↗
Prolonged His-Q interval in chronic bifascicular block. Relation to impending complete heart block.
Although prolonged infra-His conduction time in bifascicular block is suspected of denoting trifascicular disease, adquate documentation is lacking concerning the correlation between lengthened His-Q interval (H-Q) and the risk of development of complete heart block (CHB). H-Q in conducted sinus beats in patients with bifascicular block associated with Mobitz II or intermittent CHB represents the approximation of maximal H-Q prolongation prior to onset of trifascicular block. To assess this relationship between prolongation of H-Q and trifascicular block, His bundle electrocardiography (HBE) was performed in 50 patients with chronic bifascicular block exhibiting Mobitz II block or transient CHB. Mobitz II or episodic CHB was shown in all patients: within two days prior to HBE in 45/50 patients; in 39/50 patients during HBE; and following HBE in five patients. In 49/50 patients H-Q was prolonged (greater than 55 msec) and in 47 this interval was substantially lengthened (65 msec or greater). Since marked H-Q prolongation in conducted sinus beats was documented in nearly all patients with bifascicular block associated with intermittent complete trifascicular block, we conclude that a considerably lengthened H-Q interval in bifascicular block is not only a usual prerequisite but strong evidence, for impending complete heart block.
Adult↗
Alterations in ventricular contraction pattern in the Wolff-Parkinson-White syndrome. Detection by echocardiography.
The effects of abnormal ventricular activation upon the contractile pattern of the ventricles in patients with the Wolff-Parkinson-White syndrome (WPW) remain uncertain. Therefore we compared the motion of the anterior right ventricular wall (RV), the interventricular septum (IVS), and left ventricular posterior wall (LVPW) on echogram in nine patients with WPW and one patient with a coronary sinus pacemaker (CSP) to 20 normal subjects. Normal subjects manifested posterior RV motion which began and reached maximal excursion at 175 and 366 msec (group mean), respectively, after the onset of the QRS complex; posterior movement of the IVS which started and peaked at 90 and 30 msec, respectively; and anterior contraction of the LVPW which began and peaked at 159 and 406 msec, respectively. Five of seven patients with Type A WPW demonstrated a localized area of premature contraction of the LVPW occuring during the initial 100 msec interval following the onset of the QRS complex which was accompanied by paradoxic anterior motion of the IVS. Thereby in Type A patients initial and maximal posterior motion of the IVS occurred later, 230 (P less than 0.001) and 400 (P less than 0.05) msec, and anterior motion of the LVPW occurred earlier, 75 (P less than 0.001) and 367 (P less than 0.05) msec as compared to normal. The amplitude and duration of early contraction could be related to the prominence of the delta wave during atrial pacing. Similar premature contraction was also observed in the patient with CSP during paced beats. One Type B WPW patient exhibited abnormal IVS motion while the additional patient manifested premature LVPW contraction similat to that seen in Type A patients. The contractile pattern of the right ventricular anterior wall was recorded in five of seven Type A Wolff-Parkinson-White patients and manifested prolongation of the interval from the onset of the QRS complex to the initial posterior movement (group mean 234 msec, P less than 0.05) as compared to normal. Thus echocardiography can be used to confirm the diagnosis and to improve understanding of the pathophysiology of the Wolff-Parkinson-White syndrome.
Adolescent↗
Reflex vasodilation induced by coronary angiography in human subjects.
In order to evaluate the reflex peripheral vascular effects of coronary arteriography, forearm blood flow was measured plethysmographically and forearm vascular resistance calculated before and during coronary angiography with Hypaque-M, 75%, and Renografin-76. The injection of Hypaque into the left coronary artery resulted in a forearm vasodilation which could not be duplicated by an injection of a comparable amount of contrast into the ascending aorta, three centimeters above the coronary ostia. Forearm blood flow rose from 2.95 to 5.41 ml/min/100 ml (83.4%) and forearm vascular resistance fell from 35.8 to 19.9 mm Hg/ml/min/100 ml (44.4%). Renografin injected into the left coronary artery resulted in less forearm vasodilation (21% increase in forearm blood flow and 32% decrease in forearm vascular resistance). When coronary arteriography was repeated following injection of atropine into the brachial artery, no forearm vasodilation occurred. It is suggested that in human subjects myocardial or coronary artery receptors can be activated by the intracoronary injection of iodinated contrast media which results in a forearm vasodilation.
Angiocardiography↗
Radionuclide assessment of nitroglycerin influence on abnormal left ventricular segmental contraction in patients with coronary heart disease.
Noninvasive gated cardiac blood pool imaging with technetium-99m autologous erythrocytes was employed to differentiate reversible verus irreversible abnormal ventricular segmental contraction by regional wall and pump responses to sublingual nitroglycerin in 25 patients with chronic coronary heart disease. In 12 patients without ECG infarctions compared to 13 with infarctions, radioisotopic images demonstrated significantly greater percent decreases in end-systolic volumes (33.8 +/- 6.7 SEM vs 187 +/- 4.4; P less than 0.05) without differences in percent reductions in end-diastolicvolumes (13.7 +/- 3.9 vs 11.6 +/- 6.1; NS) and thereby significantly greater percent increases in ejection fractions (9.3 +/- 1.6 vs 4.1 +/- 2.0; P less than 0.05). In the 22 patients with regional dyssynergy, improvement in disordered pattern and extent of localized dyssynergy following antianginal action of nitroglycerin was related to ECG absence of prior infarction. These obsevations demonstrate the clinical accuracy of atraumatic scintigraphy in the detection of reversible localized dyssynergy due to myocardial ischemia in coronary heart disease.
Adult↗
Reduction of ischemic injury by sublingual nitroglycerin in patients with acute myocardial infarction.
The effect of sublingual nitroglycerin (NTG) on myocardial ischemic injury was evaluated in eleven patients with acute anterior myocardial infarction. Precordial 35-lead ST-segment maps were obtained in each patient immediately before and 3-10 minutes after 0.4 mg sublingual NTG. The following measurements were made from each ST map: N-ST (number of leads showing ST elevation greater than 1mm), sigmaST (total ST elevation in all leads), ST (average ST-segment elevation in those leads with less than 1mm elevation). Following 0.4 mg sublingual NTG evidence of myocardial ischemic injury as assessed by ST-segment mapping decreased in association with reduction of heart rate X systolic blood pressure product (10.80 X 10(3) to 9.49 X 10(3), P less than 0.001). Group mean values diminished significantly for N-ST (18.1 to 14.4, P less than 0.001), sigma ST (37.9 to 30.1 P less than 0.005) and ST (1.7 to 1.4, P less than 0.001). Evaluation performed by the technique of precordial ST-segment mapping suggests that sublingual nitroglycerin in a commonly employed clinical dose is associated with evidence of reduced ischemic cardiac injury in patients with acute myocardial infarction. This effect appears to be related to reduction of myocardial oxygen demand by the nitrate.
Acute Disease↗
Pharmacological mechanisms for left ventricular unloading in clinical congestive heart failure. Differential effects of nitroprusside, phentolamine, and nitroglycerin on cardiac function and peripheral circulation.
We compared cardiocirculatory actions of the commonly employed systemic vasodilators, intravenous (iv) nitroprusside (NP), iv phentolamine (PH), and sublingual nitroglycerin (NTG), causing left ventricular (LV) unloading in 29 chronic coronary subjects with congestive failure to determine whether they produce disparate responses in LV function by different relaxing actions on systemic resistance and capacitance beds. Each drug equally lowered systemic arterial pressures to a small extent, whereas heart rate rose slightly with NTG. Cardiac catheterization showed a decline in end-diastolic pressure with NTG (19 to 8 mm Hg) which was greater (P less than 0.05) than with NP and PH (21 to 11). Cardiac index increased (P less than 0.05) during NP (2.68 to 2.93 liters/min per m2) and PH (2.60 to 3.02) but was unchanged (2.83) by NTG. Stroke work increased with PH, ejection fraction rose with NP and PH, and mean ejection rate increased with each, whereas pressure-time per minute fell and end-diastolic volume decreased with each agent. Total systemic vascular resistance declined (P less than 0.001) during NP and PH (1,475 to 1,200 dynes sec cm-5) but was unchanged (1,487) by NTG. Plethysmographically, forearm vascular resistance (FVR) decreased (P less than 0.01) with NP and PH (61.6 to 39.1 mm Hg/ml per 100 g/min) but not (52.4) by NTG. The decreases in venous tone (VT) with NTG (18.2 to 9.3 mm Hg/ml) and NP (18.5 to 9.8) were greater (P less than 0.05) than with PH (18.8 to 13.1) FVR/VT percent changes of 0.96, 1.62, and 0.53 with NP, PH, and NTG indicated balanced systemic arteriolovenous relaxation by iv NP, greater arteriolar dilation with iv PH, and predominant venous dilation by sublingual NTG. Thus, vasodilators produce disparate modifications of LV function by their differing alterations of preload and impedance, which are dependent upon relative extents of relaxation of systemic resistance and capacitance vessels characteristic of each agent as used clinically.
Adult↗
Intraventricular free wall dissection causing acute interventricular communication with intact septum in myocardial infarction.
This report delineates a previously unrecognized complication of acute myocardial infarction, an intraventricular wall dissection producing interventricular communication without septal perforation. The clinical, hemodynamic, and pathologic features of this unique condition are documented, as well as the factors important in the mechanism of its production.
Aged↗