bluuebunny/crossref_metadata_2025 huggingface dataset:
Immediate functional recovery and avoidance of reperfusion injury with surgical revascularization of short-term coronary occlusion.
Authors: Vinten-Johansen J , Edgerton T A , Howe H R , Gayheart P A , Mills S A , Howard G , Cordell A R
Published: June 2011

Functional recovery with surgical revascularization of acutely ischemic myocardium has not been compared with its nonsurgical counterpart in experimental preparations of coronary occlusion. This study compares the functional and metabolic recovery of ischemic (1 hr coronary occlusion) segments revascularized either by restoration of coronary patency (simulating nonsurgical recanalization, e.g., angioplasty) or by surgical revascularization with multidose hypothermic potassium blood cardioplegic solution. Twenty-two anesthetized open-chest dogs were instrumented with Millar micromanometer-tip catheters to measure left ventricular and aortic pressures. Piezoelectric ultrasonic dimension gauges were implanted in the subendocardium supplied by the left anterior descending coronary artery to measure segmental contractile function. In five dogs, only biopsy samples were obtained for control measurements of ATP, creatine phosphate, and tissue water content. In the remaining 17 dogs, the left anterior descending artery and collaterals were ligated for 1 hr. The ligatures were removed in eight dogs and coronary perfusion continued for 2 hr, simulating nonsurgical reperfusion. The remaining nine dogs were placed on cardiopulmonary bypass and the hearts were arrested for 1 hr with multidose (every 20 min) blood cardioplegic solution enhanced with glutamate and aspartate, simulating surgical revascularization (coronary artery bypass grafting). The coronary ligatures were not released until the second cardioplegic infusion, simulating graft placement. One hour of coronary occlusion placed 39.4 +/- 2.5% of the left ventricle at risk, and converted active systolic shortening to persistent paradoxical bulging (25.2 +/- 2.2% to -5.8 +/- 1.2% systolic shortening).(ABSTRACT TRUNCATED AT 250 WORDS)
Diminished stroke volume during inspiration: a reverse thoracic pump.
Authors: Olsen C O , Tyson G S , Maier G W , Davis J W , Rankin J S
Published: June 2011

In 12 conscious dogs, a three-dimensional array of pulse-transit ultrasonic transducers was used to measure left ventricular anterior-posterior minor, septal-free wall minor, and basal-apical major diameters. Matched micromanometers measured left ventricular, right ventricular, and intrapleural pressures. Electromagnetic ascending aortic blood flow and right ventricular transverse diameter were measured in five of the dogs. A major cause of the inspiratory decline in stroke volume in this preparation appeared to be reflex tachycardia and autonomic changes associated with inspiration. However, when heart rate was controlled by atrial pacing or pharmacologic autonomic attenuation (propranolol and atropine), stroke volume still decreased around 10%, with an inspiratory decrease in pleural pressure of 10 mm Hg. Based on the measurements of ventricular dimension, venous return to the right ventricle appeared to be augmented significantly during inspiration and the transient increase in right ventricular volume was associated with leftward interventricular septal shifting and altered diastolic left ventricular geometry. However, left ventricular end-diastolic volume was changed minimally, implying that alterations in preload were not important. Moreover, transmural left ventricular ejection pressure, calculated as intracavitary minus pleural pressure, was not significantly changed, and it seemed that neither pressure nor geometric components of afterload were altered significantly by inspiration. The inspiratory fall in left ventricular stroke volume correlated best with the decline in intracavitary left ventricular ejection pressure referenced to atmospheric pressure. It is hypothesized that during ejection, left ventricular pressure referenced to atmospheric pressure is the hydraulic force effecting stroke volume and that the decline in this effective left ventricular ejection pressure is responsible for the inspiratory fall in stroke volume through a reverse thoracic pump mechanism.
Production of platelet-activating factor by human vascular endothelial cells: evidence for a requirement for specific agonists and modulation by prostacyclin.
Authors: Zimmerman G A , McIntyre T M , Prescott S M
Published: June 2011

Primary cultures of confluent endothelial cells derived from human umbilical veins produce platelet-activating factor (PAF) (1-alkyl-2-acetyl-sn-glycero-3-phosphocholine) when stimulated with appropriate agonists. Highly purified human thrombin and calcium ionophore A23187 stimulate the incorporation of [3H] acetate into a lipid product that has been identified as PAF by its behavior in thin-layer chromatographic and high-performance liquid chromatographic systems, the presence of characteristic biologic activity, and appropriate response to phospholipases. A number of other humoral mediators, examined because they directly influence the activity of vascular cells or because they may mediate endothelial injury, do not stimulate PAF production by endothelial cells. This indicates that the synthesis of PAF by cultured human endothelial cells is a response to specific agonists and is not an unregulated event that occurs as a result of nonspecific cellular perturbation. The PAF produced by thrombin-treated endothelial cells is a potent stimulus for platelet activation, as assayed by the aggregation of human platelets in autologous plasma. The production of PAF by endothelial monolayers is attenuated by prostacyclin, another product of stimulated endothelial cells. Conversely, PAF production is enhanced by treatment of the endothelial cells with indomethacin, an inhibitor of prostacyclin synthesis from arachidonic acid, indicating that endogenously generated prostacyclin may modulate PAF synthesis. The potential to synthesize PAF, a unique lipid autocoid that stimulates the activation of both platelets and polymorphonuclear leukocytes, suggests that endothelial cells can directly influence the activity of these circulating effector cells. This biologic potential may be important in the interaction of the endothelium with circulating blood cells in physiologic conditions and in syndromes of vascular injury.
Detection of local abnormalities in ventricular activation sequence by body surface isochrone mapping in patients with previous myocardial infarction.
Authors: Ikeda K , Kubota I , Igarashi A , Yamaki M , Tsuiki K , Yasui S
Published: June 2011

Body surface isochrone mapping was performed in 36 normal subjects and in 85 patients with previous myocardial infarction. Eighty-seven unipolar electrocardiograms distributed over the anterior chest and the back were recorded simultaneously. For each lead, activation time was measured as the time from the onset of QRS to the peak of the R wave. The lead points where R waves were not observed were designated the "no R wave area" (NR area). Isochrone maps of normal subjects had a consistent pattern, with isochrone lines extending from the right upper anterior chest to the left anterior chest and then to the back. NR area was small and was located only on the right upper chest or the upper back. On the isochrone maps of patients with myocardial infarction, abnormal findings were observed; NR area was found in 26 of 28 patients with anterior infarction on the upper to middle anterior chest, in 13 of 22 patients with inferior infarction on the lower chest, and in 24 of 25 patients with anterior and inferior infarction on the upper to lower anterior chest. Activation time was delayed near the NR area (peri-NR area delay) in 37 patients. In patients with apical infarction, an islandlike zone of delayed activation was typically found on the left precordium. These abnormal patterns are considered to indicate local abnormalities in the activation of infarcted myocardium; the NR area indicates dead unexcitable scar, and the peri-NR area delay and islandlike zone of delayed activation indicate partially infarcted myocardium of slow activation. Patients with NR area had greater degree of left ventricular asynergy and lower ejection fraction than those without.(ABSTRACT TRUNCATED AT 250 WORDS)
Senning repair for transposition of the great arteries in the first week of life.
Authors: Matherne G P , Razook J D , Thompson W M , Lane M M , Murray C K , Elkins R C
Published: June 2011

Infants with D-loop transposition of the great arteries (D-TGA) may have unacceptable results after the balloon septostomy while awaiting surgery. It has been our policy to repair defects in infants with D-TGA and intact ventricular septum or small ventricular septal defect at the time of diagnosis. We report our experience with the Senning operation in 18 newborns less than 1 week of age. The mean age at operation was 3 days (range 12 hr to 7 days) and the mean weight was 3.5 kg (range 2.8 to 4.8). There were two early postoperative deaths (11%) and one late death (5%). Early mortality was associated with preoperative acidosis and congestive heart failure. Late mortality was associated with severe left ventricular outflow tract obstruction (LVOTO). The 15 long-term survivors have been followed for an average of 27 months and 11 of the 16 perioperative survivors have undergone postoperative catheterizations. There was no evidence of systemic or pulmonary venous obstruction. One patient developed LVOTO that led to his death. Two patients had residual atrial shunts. Electrocardiograms revealed no major arrhythmias. All patients are clinically asymptomatic. Good hemodynamic, electrocardiographic, and clinical results can be obtained with correction of D-TGA in the first week of life.
Effects of sublingual nifedipine on hemodynamics and systolic and diastolic function in patients with hypertrophic cardiomyopathy.
Authors: Betocchi S , Cannon R O , Watson R M , Bonow R O , Ostrow H G , Epstein S E , Rosing D R
Published: June 2011

The hemodynamic effects of sublingual nifedipine were examined in 36 patients with hypertrophic cardiomyopathy. Twenty-one patients were initially given 20 mg and 15 patients were given 10 mg of the drug; 30 min after this first dose 26 patients received 10 mg and one patient 20 mg as a second dose. Hemodynamic findings in patients who received different doses of the drug were similar. Peak effects included an increase in heart rate from 79 +/- 12 to 91 +/- 14 (mean +/- 1 SD) beats/min (p less than .01), and a decrease in mean blood pressure from 89 +/- 12 to 77 +/- 10 mm Hg (p less than .01). Cardiac index increased after nifedipine (2.8 +/- 0.6 to 3.3 +/- 0.8 liters/min/m2; p less than .01); stroke volume index, however, did not change (36 +/- 7 to 36 +/- 8 ml/beat/m2; NS). Peripheral vascular resistance index fell significantly from 822 +/- 261 to 610 +/- 197 dynes X sec X cm-5 (p less than .01). Overall, left ventricular outflow tract gradient (LVOTG) did not change in patients with significant (greater than or equal to 30 mm Hg) basal LVOTG (75 +/- 22 to 83 +/- 22 mm Hg; NS), but it increased significantly in those six patients in whom peripheral vascular resistance fell by 25% or more (73 +/- 28 to 99 +/- 22 mm Hg; p less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)
Global and regional right ventricular function in normal infants and infants with transposition of the great arteries after Senning operation.
Authors: Trowitzsch E , Colan S D , Sanders S P
Published: June 2011

Echocardiographic assessment of right ventricular size, global function, and regional wall motion was performed in 29 normal infants and 19 infants with transposition of the great arteries 1 to 41 months after they underwent the Senning procedure. Sixteen of the patients with transposition of the great arteries were in clinically good condition and three had congestive heart failure. The right ventricular endocardial surface was digitized frame by frame for a complete cardiac cycle in both subxiphoid long-axis (coronal plane) and short-axis (parasagittal plane) views, and the cross-sectional area and the area change fraction (AF) were calculated. In each plane the right ventricular wall was subdivided into four anatomic regions (infundibular, free wall, diaphragmatic, and septal). With the use of a floating point center of mass model the direction and average extent of motion of the endocardium was determined for each region. In normal infants the infundibular and free wall portions of the right ventricle exhibited the greatest inward motion and the septal segments the least inward motion. Although the maximal area in both long-axis (r = .85) and short-axis (r = .85) views was highly correlated with body surface area (BSA), neither global nor regional function was significantly correlated with age or BSA. In clinically well patients after Senning procedure regional right ventricular function followed an entirely different pattern than that seen in normal infants. The endocardium of the septal segments showed the greatest inward motion in systole. In contrast to those in normal infants, maximal and minimal cross-sectional areas did not correlate significantly with BSA.(ABSTRACT TRUNCATED AT 250 WORDS)
The effects of the rate of intravenous infusion of streptokinase and the duration of symptoms on the time interval to reperfusion in patients with acute myocardial infarction.
Authors: Lew A S , Laramee P , Cercek B , Rodriguez L , Shah P K , Ganz W
Published: June 2011

We studied the influence of the following variables on the time interval from initiation of an intravenous infusion of 750,000 U of streptokinase until reperfusion (reperfusion time) in 140 consecutive patients with an evolving acute myocardial infarction: (1) the rate of infusion of streptokinase, (2) the duration of chest pain before initiation of treatment, (3) patient age, (4) patient sex, (5) location of infarction, (6) history of previous myocardial infarction, and (7) pretreatment pathologic Q waves. The time of reperfusion was recognized by clinical criteria that were completely concordant with the anatomic findings in all 119 patients in whom patency or occlusion of the artery of infarction was established at delayed angiography (n = 116) or at postmortem examination (n = 3). The mean reperfusion time for the 129 patients for whom data were available was 49 +/- 36 min. The reperfusion time was inversely related to the rate of infusion of streptokinase (r = .41, p less than .001), but this effect of infusion rate appeared to plateau at rates of greater than 500 U/kg/min. In the 64 patients receiving infusions at rates of 500 U/kg/min or less, the mean reperfusion time was 60 +/- 40 min, whereas in the 58 patients receiving the drug at rates greater than 500 U/kg/min it was 35 +/- 22 min (p less than .001). The duration of chest pain before treatment was the only other studied variable found to influence the reperfusion time, but only at infusion rates of less than 250 U/kg/min (r = .6, p less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)
Effects of intravascular volume state on the value of pulsus paradoxus and right ventricular diastolic collapse in predicting cardiac tamponade.
Authors: Cogswell T L , Bernath G A , Wann L S , Hoffman R G , Brooks H L , Klopfenstein H S
Published: June 2011

Both pulsus paradoxus and right ventricular diastolic collapse detected by two-dimensional echocardiography are noninvasive markers of impaired cardiac function in cardiac tamponade, yet the reliability of each may vary with the patient's state of hydration. To examine the relative value of these noninvasive markers at various states of hydration, we studied five chronically prepared, conscious mongrel dogs during 37 episodes of cardiac tamponade at three different intravascular volumes. We continuously measured cardiac output (electromagnetic flowmeter), aortic blood pressure, right atrial blood pressure, intrapericardial pressure, and respirations. Intravascular volume was varied by adjusting the mean right atrial blood pressure to hypovolemic (-2 to -6 mm Hg), euvolemic (0 to 4 mm Hg), or hypervolemic (6 to 10 mm Hg) levels. The sensitivity and specificity of right ventricular diastolic collapse in predicting increases in intrapericardial pressure remained high at all levels of hydration. Pulsus paradoxus showed good sensitivity and specificity at low intravascular volumes, but both sensitivity and specificity declined at higher intravascular volumes. Thus right ventricular diastolic collapse was more sensitive and more specific than pulsus paradoxus in detecting increases in intrapericardial pressure during euvolemia and hypervolemia whereas the two tests were equally valuable in hypovolemic states.
Increased lung vasoreactivity in children from Leadville, Colorado, after recovery from high-altitude pulmonary edema.
Authors: Fasules J W , Wiggins J W , Wolfe R R
Published: June 2011

Cardiac catheterization was performed on seven children after recovery from high-altitude pulmonary edema. All were life-long residents at elevations above 10,000 feet. Three of the seven had developed pulmonary edema without antecedent travel to low altitude but had an upper respiratory infection. Response of pulmonary arterial pressure to 16% inspired oxygen in all seven was compared with that in six well children who resided at a similar altitude and had no history of high-altitude pulmonary edema. With hypoxia the susceptible patients had a greater mean pulmonary arterial pressure (56.3 +/- 23.8) than the nonsusceptible children (18.8 +/- 3.9, p less than .05). Comparison with historical hemodynamic responses in children at high altitudes showed a similar greater mean pulmonary arterial pressure in the susceptible children. Thus, in children from high altitudes, increased pulmonary vasoreactivity to hypoxia may play a role in the pathogenesis of high-altitude pulmonary edema. The development of pulmonary edema in high-altitude residents with upper respiratory infections and no antecedent low-altitude journey is consistent with the presence of other factors such as inflammation, which may play a role in the pathogenesis of the edema. The finding of right ventricular hypertrophy on an electrocardiogram in children from high altitudes may be predictive of their susceptibility to high-altitude pulmonary edema.
Intermittent failure of local conduction during ventricular tachycardia.
Authors: Miller J M , Vassallo J A , Hargrove W C , Josephson M E
Published: June 2011

Forty-three patients with sustained ventricular tachycardia (VT) caused by prior myocardial infarction underwent intraoperative endocardial activation mapping during a total of 122 episodes of VT. Electrograms obtained during mapping were analyzed to determine the prevalence of local conduction failure during VT (defined as a portion of the local electrogram that did not repeat with every tachycardia cycle). Local conduction failure during VT was observed in 37 (86%) patients and 73 (65%) tachycardias. VT in which local conduction failure was observed were faster than VTs without local conduction failure (cycle length 315 vs 345 msec; p less than .05). Local conduction failure occurred most frequently at or near sites having the earliest recorded electrical activity during VT ("site of origin"). Twenty-three patients also had sinus rhythm endocardial mapping at the time of surgery. Areas with abnormal or fractionated electrograms in sinus rhythm were more likely to demonstrate local conduction failure in VT than areas with normal electrograms in sinus rhythm (16% vs 8%; p less than .01). Although the mechanism responsible for local conduction failure in VT is unclear, it is a common occurrence and is significant in that it can occasionally mimic "early" sites of endocardial activation, unless enough VT cycles are observed at a given site.
Abnormal signal-averaged electrocardiograms in patients with nonischemic congestive cardiomyopathy: relationship to sustained ventricular tachyarrhythmias.
Authors: Poll D S , Marchlinski F E , Falcone R A , Josephson M E , Simson M B
Published: June 2011

We assessed whether signal-averaged electrocardiography could identify patients with sustained ventricular arrhythmias in 41 patients with non-ischemic cardiomyopathy. Twelve of these patients presented with sustained ventricular arrhythmia and 29 patients had no history of sustained ventricular arrhythmias. The mean ejection fractions in the groups were 30 +/- 9% and 24 +/- 9%, respectively. Results were compared with signal-averaged electrocardiograms in 55 normal individuals. The filtered QRS duration was longest in patients with sustained ventricular arrhythmias (130.2 +/- 19.5 vs 105.0 +/- 13.1 msec in the group without sustained ventricular arrhythmia, p less than .001 and 95.9 +/- 9.1 in the normal group, p less than .001). The voltage in the last 40 msec of the filtered QRS was lower in the sustained ventricular arrhythmia group (11.3 +/- 9.3 microV) than the group without sustained ventricular arrhythmia (53.5 +/- 28.3 microV; p less than .001) or the normal group (53.7 +/- 25.2 microV; p less than .001). Eighty-three percent of patients in the sustained ventricular arrhythmia group had an abnormal signal-averaged electrocardiogram characterized by both a long filtered QRS duration and a late potential of low voltage level; only 2% of normal subjects and 14% of patients without sustained ventricular arrhythmias had an abnormal signal-averaged electrocardiogram. The signal-averaged electrocardiogram can identify patients with nonischemic congestive cardiomyopathy and sustained ventricular arrhythmias.
Coronary angioplasty of multiple vessels: short-term outcome and long-term results.
Authors: Cowley M J , Vetrovec G W , DiSciascio G , Lewis S A , Hirsh P D , Wolfgang T C
Published: June 2011

Experience with percutaneous transluminal coronary angioplasty (PTCA) of multiple vessels was reviewed to assess short-term outcome and long-term results. PTCA of multiple vessels was performed in 100 of the initial 500 patients (20%) who underwent PTCA at the Medical College of Virginia between July 1979 and August 1984. Eighty-nine percent had class 3 or 4 angina, and 66% had unstable angina. Two-thirds had severe stenosis of two vessels or major branches and one-third had three-vessel disease. One or more significant lesions were dilated in two vessels in 84 patients, in three vessels in 14 patients, and in four vessels in two patients. PTCA of 273 lesions (2.7/patient) was attempted (range two to eight per patient) with angiographic success in 250 lesions (91.6%). Primary success (angiographic and clinical improvement) was achieved in 95 of 100 patients (95%); 84% had success in multiple vessels, and 79% had success in all attempted lesions. Complications occurred in 11 patients (11%); four patients (4%) underwent urgent bypass surgery and four additional patients (4%) had myocardial infarction. Long-term results were assessed in 44 patients with primary success who had follow-up of more than 1 year (mean 26 months) after multiple-vessel PTCA. Twenty-eight patients (64%) remain event-free and improved and 48% are event-free and asymptomatic. Clinical recurrence developed in 15 patients (34%); four had sustained improvement with repeat PTCA, three remain improved with medical therapy, and eight (18%) have undergone bypass surgery during follow-up. One patient (2.3%) developed late myocardial infarction, and deaths have occurred in the follow-up cohort.(ABSTRACT TRUNCATED AT 250 WORDS)
Comparative effects of volume loading, dobutamine, and nitroprusside in patients with predominant right ventricular infarction.
Authors: Dell'Italia L J , Starling M R , Blumhardt R , Lasher J C , O'Rourke R A
Published: June 2011

To assess the value of volume loading and to determine the relative efficacy of dobutamine compared with nitroprusside therapy in acute right ventricular infarction (RVMI), 13 patients with clinical, hemodynamic, and radionuclide angiographic evidence of RVMI were evaluated. In 10 patients who had an initial pulmonary arterial wedge pressure less than 18 mm Hg, volume loading did not improve cardiac index (1.9 +/- 0.5 [SD] to 2.1 +/- 0.4 liters/min/m2), despite significant increases in mean right atrial pressure (11 +/- 2 to 15 +/- 2 mm Hg, p less than .001) and pulmonary arterial wedge pressure (10 +/- 4 to 15 +/- 2 mm Hg, p less than .001). Nine patients received dobutamine or nitroprusside in random order, while hemodynamic measurements and radionuclide angiograms were obtained simultaneously. Compared with nitroprusside, dobutamine produced a statistically significant increase in cardiac index (2.0 +/- 0.4 to 2.7 +/- 0.5 vs 2.1 +/- 0.4 to 2.3 +/- 0.5 liters/min/m2, p less than .001), stroke volume index (29 +/- 6 to 36 +/- 8 vs 29 +/- 6 to 30 +/- 6 ml/m2, p = .02), and right ventricular ejection fraction (30 +/- 8% to 42 +/- 7% vs 34 +/- 8% to 37 +/- 4%, p less than .01) by two-way analysis of variance. We conclude that volume loading does not improve cardiac index in patients with acute RVMI despite a rise in cardiac filling pressures and that infusion of dobutamine, after appropriate volume loading, produces a significant improvement in cardiac index and right ventricular ejection fraction over those after infusion of nitroprusside.
Systemic and transcardiac platelet activity in acute myocardial infarction in man: resistance to prostacyclin.
Authors: Mueller H S , Rao P S , Greenberg M A , Buttrick P M , Sussman I I , Levite H A , Grose R M , Perez-Davila V , Strain J E , Spaet T H
Published: June 2011

There is increasing evidence that platelets play an important role in the pathogenesis of acute ischemic heart disease. Therefore an understanding of factors that influence platelet performance is important. This study was undertaken (1) to characterize during evolving myocardial infarction platelet activity in the peripheral circulation and across the ischemic/infarcting myocardial compartment, the locus of presumed platelet hyperactivity, and (2) to evaluate the effects of prostacyclin (PGI2), a most potent antiplatelet agent and vasodilator. A total of 59 patients with evolving myocardial infarction were studied. Twenty-two patients were instrumented with arterial and coronary sinus catheters and received intravenous infusion of PGI2, 13 +/- 4.5 ng/kg/min (mean +/- SD), for 90 min. In 15 patients with anterior myocardial infarction, transcardiac platelet function and response to PGI2 were studied. Plasma levels of beta-thromboglobulin (beta-TG) and of thromboxane B2 (TxB2), in vivo measures of platelet activity, were elevated three- and 10-fold. 6-Keto-prostaglandin F 1 alpha, the stable end product of PGI2, was less than 10 pg/ml, reflecting a leftward shift of the TxB2/PGI2 ratio. Platelets circulating during evolving myocardial infarction ("ischemic platelets") were hyperaggregable in response to ADP and relatively resistant to PGI2, both in vivo and in vitro. Concentrations of platelet cyclic AMP and the cyclic AMP response to PGI2 were diminished. The platelet hyperreactivity, expressed by plasma beta-TG, platelet aggregation, and PGI2-induced inhibition of aggregation, was most intense early during infarct evolution and decreased with time. The increased platelet performance resulted in "platelet fatigue," indicated by decreased contents of beta-TG of the ischemic platelet and decreased TxA2 production in response to collagen. However, the ischemic platelet produced twice normal TxA2 in response to arachidonic acid (stimulus and substrate), demonstrating a heightened metabolic capacity. TxA2 was produced across the ischemic/infarcting compartment in 10 of 15 patients with anterior myocardial infarction. The antiplatelet effect of PGI2 was greatly diminished. In summary, the data define an abnormal pattern of platelet behavior during evolving myocardial infarction, characterized by a proaggregatory environment, heightened platelet reactivity in both the peripheral and coronary circulation, and relative resistance to PGI2. The clinical consequences of the data are that the patient in the acute phase of myocardial infarction may benefit from suppression of platelet function and requires significantly greater doses of PGI2 than normal subjects.(ABSTRACT TRUNCATED AT 400 WORDS)
Determination of left ventricular mass in dogs with rapid-acquisition cardiac computed tomographic scanning.
Authors: Feiring A J , Rumberger J A , Reiter S J , Skorton D J , Collins S M , Lipton M J , Higgins C B , Ell S , Marcus M L
Published: June 2011

The development of left ventricular hypertrophy in patients with heart disease often has far-reaching clinical implications with respect to overall morbidity and mortality. Approaches used to assess left ventricular mass include electrocardiography, echocardiography, contrast ventriculography, single photon-emission tomography, and conventional computed tomography. However, all of these modalities suffer from some major draw back that precludes widespread application to all patients. In this study we assessed the accuracy of determinations of left ventricular mass in 22 dogs by rapid-acquisition (50 msec) computed axial tomography (RACAT), an ultrafast computed tomographic (CT) instrument. Electrocardiographically triggered, end-diastolic, short-axis cardiac scans were obtained from apex to base during administration of intravenous iodinated contrast. Myocardial edges were determined for each tomographic scan by two methods: the regional half-contour method (the CT density half way between that of the left ventricular myocardium and adjacent ventricular cavities or lung) and "interactive plateau thresholding" of the cardiac borders. Left ventricular mass by RACAT was calculated as the sum of the mass of each individual scan from apex to base (modified Simpson's rule). Postmortem left ventricular mass ranged from 58 to 160 g. The correlation between true left ventricular mass and tomographically determined mass was excellent (r = .99), with the slope and y intercept not statistically different from 1 and 0, respectively. The standard error of the estimate was 4.1 g. Interobserver and intraobserver variability for determining left ventricular mass demonstrated excellent agreement (r = .99 and r = .99, respectively). We conclude that quantitative assessment of left ventricular mass can be accurately and reproducibly performed in dogs by rapid acquisition CT scanning. It is likely that this technique will be readily transferable to the clinical settings and prove to be an important method for quantifying left ventricular mass in patients.
Treatment of canine permeability pulmonary edema: short-term effects of dobutamine, furosemide, and hydralazine.
Authors: Molloy W D , Lee K Y , Girling L , Prewitt R M
Published: June 2011

The effects of treatment of oleic acid pulmonary edema with dobutamine, furosemide, and hydralazine on cardiopulmonary function in 24 dogs were investigated. Pulmonary capillary wedge pressure (PCWP) was adjusted to approximately 7 mm Hg; 45 min after oleic acid (0.08 ml/kg), dogs were randomly divided into a control group, in which PCWP was maintained at approximately 7 mm Hg, and into treatment groups as described above. Mean time-averaged PCWP was 2.3 mm Hg in dogs treated with dobutamine, 4.1 mm Hg with furosemide, and 4.4 mm Hg with hydralazine. Four hours of treatment with dobutamine and furosemide significantly (p less than .01) reduced accumulation of lung water compared with the control and hydralazine groups. Qs/Qt was lower (p less than .05) with dobutamine and furosemide compared with the other groups. In dogs given hydralazine, cardiac output (CO) and systemic vascular resistance (SVR) remained constant over the 4 hr treatment interval. In contrast, in all other groups, SVR increased and CO decreased (both p less than .05). The short-term pulmonary effects of the above drugs are probably explained by differences in PCWP and/or by regional pulmonary vascular effects.
Cardiac Doppler flow velocities in human fetuses.
Authors: Reed K L , Meijboom E J , Sahn D J , Scagnelli S A , Valdes-Cruz L M , Shenker L
Published: June 2011

Cardiac Doppler flow velocity studies were performed in normal human fetuses between 18 and 40 weeks of gestation. Two-dimensional linear array and sector scanning techniques were used for the initial evaluation of the fetuses, which included a standard ultrasound examination to determine normal anatomy and estimated gestational age and weight. Fetal cardiac ultrasound examination was then performed, with four-chamber, short-axis/great vessel, long-axis/left ventricular outflow tract, and aortic arch views obtained. Pulsed echo Doppler instrumentation was used to obtain flow velocity measurements through the tricuspid, pulmonary outflow, mitral, and aortic outflow regions. Calculation of transvalve volume flow for mitral and tricuspid valves was performed by combining the valve anulus sizes and calculated mean temporal velocities for the valves. Maximal flow velocities were greater through the tricuspid (mean maximal velocity 51 +/- 1.2 [SE] cm/sec) than through the mitral (47 +/- 1.1 cm/sec; p less than .05) valve regions, with a wide range of scatter for results between fetuses but less than 6% average variation in the individual fetuses during gestation. For 18 fetuses, right heart dimensions and volume flows (mean 307 + 30 ml/kg/min) were greater than left heart dimensions and volume flows (232 +/- 25 ml/kg/min). Doppler echocardiography may prove to be useful as an adjunct to imaging echocardiography for evaluation of fetal cardiac anatomy and function.
Cardiovascular involvement in osteogenesis imperfecta.
Authors: Hortop J , Tsipouras P , Hanley J A , Maron B J , Shapiro J R
Published: June 2011

While aortic root dilatation and valvular dysfunction have been well-documented in osteogenesis imperfecta (OI), the nature and extent of cardiovascular involvement in OI have not been clearly delineated. A clinical and echocardiographic survey involving 109 individuals with various nonlethal OI syndromes from 66 separate families was undertaken. Clinically discernible valvular dysfunction was encountered in only four of the 109 individuals (aortic regurgitation in two, aortic stenosis in one, and mitral valve prolapse in one), none of whom were related. Aortic root dilatation was recognized echocardiographically in eight (12.1%) of 66 individuals comprising a subset of the sample in which each family was represented by a single individual. The extent of the aortic root dilatation was mild (the largest dimension measuring 4.3 cm) and was unrelated to the age of the individual. Dilatation was seen in each of the different OI syndromes but was strikingly segregated within certain families (p less than .001). In the same subset of 66 individuals, mitral valve prolapse was encountered in two or 6.9% of the 29 individuals aged 15 years or greater in whom adequate studies were obtained. This observed frequency was not different from that seen in a normal adult population. Aortic root dilatation appears to represent a distinct phenotypic trait in patients with OI that is nonprogressive and occurs in about 12% of affected individuals. Whether mitral valve prolapse should be considered as a part of the cardiovascular phenotype in OI, or alternately segregates as an independent autosomal dominant trait has yet to be determined.
Cardiovascular response to dynamic exercise in patients with chronic symptomatic mild-to-moderate and severe aortic regurgitation.
Authors: Kawanishi D T , McKay C R , Chandraratna P A , Nanna M , Reid C L , Elkayam U , Siegel M , Rahimtoola S H
Published: June 2011

Fifteen patients with symptomatic mild-to-moderate and severe chronic aortic regurgitation (AR) performed supine bicycle exercise while measurements of rest and exercise hemodynamics and left ventricular function were obtained. A continuous Doppler method was used to determine the change in distribution of total left ventricular stroke volume between forward stroke volume and regurgitant volume (RgV) with exercise. The pulmonary arterial wedge pressure (PAWP) was lower in the mild-to-moderate AR group than in the severe AR group at rest (8 +/- 1.2 vs 19 +/- 3.6 mm Hg, p = 0.01) and during exercise (15 +/- 3.9 vs 30 +/- 4.3 mm Hg, p = .02). In all patients there were increases in heart rate (78 +/- 4 to 96 +/- 5 beats/min, p less than .001), forward stroke volume (41 +/- 2 to 46 +/- 2 ml/m2), and the cardiac index (3.1 +/- 0.2 to 4.4 +/- 0.3 liters/min-m2, p less than .001), despite a fall in total left ventricular stroke volume index from 84 +/- 5 to 76 +/- 5 ml/m2 (p = .03). The systemic vascular resistance (SVR) decreased with exercise from 1277 +/- 72 to 1031 +/- 64 dynes-sec/cm5 (p less than .001), and the RgV and regurgitant fraction (RgF) both decreased with exercise from 43 +/- 5 ml/m2 to 30 +/- 4 ml/m2 (p = .002) and 0.50 +/- 0.03 to 0.37 +/- 0.03 (p less than .001), respectively. Left ventricular ejection fraction increased on exercise from 0.51 +/- 0.03 to 0.55 +/- 0.03 (p = .02) for the group, but it either decreased or failed to increase by at least 0.05 in seven of 13 patients. The change in ejection fraction on exercise was directly related to the change in SVR (r = .80, p less than .001). We conclude that: in patients with mild-to-moderate AR, the PAWP is generally normal at rest and exercise, in most of those with severe AR, the PAWP is elevated at rest and increases significantly with exercise, which is the likely mechanism for dyspnea on exertion in these patients, the cardiac index in both groups is normal at rest and increases on exercise, the increase in cardiac output results from both an increased heart rate and forward stroke volume, the increase in forward stroke volume results from reductions of RgV and RgF, the RgV and RgF are decreased due to a decreased SVR, and the ejection fraction response to exercise is variable and correlates best with changes in SVR with exercise.
The detection of atrial and ventricular septal defects with electrocardiographically synchronized magnetic resonance imaging.
Authors: Lowell D G , Turner D A , Smith S M , Bucheleres G H , Santucci B A , Gresick R J , Monson D O
Published: June 2011

To evaluate the detectability of cardiac septal defects by electrocardiographically synchronized (ECG-gated) magnetic resonance imaging (MRI), 48 subjects were imaged, including 18 normal and 30 abnormal subjects in whom 22 ventricular septal defects (VSDs) and nine atrial septal defects (ASDs) had been diagnosed angiographically. Two radiologists with ECG-gated cardiac MRI experience read the scans in a blinded fashion, and the results were evaluated by receiver operator characteristic curve analysis. The detectability of VSDs appeared greater than that of ASDs, although statistical significance at the .05 level was not achieved. The reported sensitivity and specificity of echocardiography in the detection of VSDs is comparable to MRI, whereas echocardiography probably is superior to MRI for detection of ASDs. Although MRI is potentially valuable in the diagnosis of various complex congenital cardiac defects, echocardiography is probably superior in the detection of VSDs and ASDs.
Respiratory system impedance in patients with acute left ventricular failure: pathophysiology and clinical interest.
Authors: Depeursinge F B , Depeursinge C D , Boutaleb A K , Feihl F , Perret C H
Published: June 2011

To investigate the relationship between alterations in lung mechanics and acute pulmonary vascular congestion, repeated measurements of the respiratory system impedance (Zrs) were performed in 11 patients with and in seven without acute left ventricular failure. Indexes of Zrs were obtained by calculating the average and slope of the resistance and reactance in low (10 to 20 Hz) and high (20 to 50 Hz) frequency intervals. Zrs indexes in patients with ventricular failure differ significantly from those in patients without failure. Pulmonary vascular congestion is regularly associated with an abnormal frequency dependence of resistance at low frequencies and with an increased resonant frequency. Discriminant analysis of Zrs indexes allows 92% correct classification of pulmonary capillary wedge pressures lower than and those equal to or higher than 18 mm Hg. Zrs differences between patients with and without left ventricular failure are consistent with the presence of a small airways obstruction even in patients with mild left ventricular failure. Furthermore, use of Zrs indexes permits moderate and severe pulmonary vascular congestion to be distinguished from one another and this is probably due to a significant narrowing of the large airways during severe left ventricular failure.
Regional myocardial and organ blood flow after myocardial infarction: application of the microsphere principle in man.
Authors: Selwyn A P , Shea M J , Foale R , Deanfield J E , Wilson R , de Landsheere C M , Turton D L , Brady F , Pike V W , Brookes D I
Published: June 2011

A physiologic means of measuring the distribution of cardiac output and regional myocardial blood flow has been developed that uses human albumin microspheres labeled with carbon-11 (11C) and external detection with positron emission tomography. Ten patients with previous myocardial infarction were studied to investigate the level of blood flow in normal and infarcted segments of the heart. After diagnostic catheterization, 4 to 6 mCi of 11C on 2 to 3 million sterile microspheres (15 to 20 micron) were mixed and injected into the apex of the left ventricle during timed withdrawal of arterial blood to obtain reference flow values. Regional activity in brain, heart, lungs, liver, spleen, and kidneys was measured tomographically. Blood flow was calculated based on the relationship between total activity in a reference flow and tissue activity in tomograms of each organ (ml/min/100 g). No adverse effects were noted after injection of the microspheres. Successive myocardial tomograms showed no loss of activity. There were no significant differences in flow values in matched regions of paired organs. Mean cerebral flow was 52.4 +/- 10.0 ml/min/100 g in the frontal lobes, 54.4 +/- 8.8 in the temporal lobes, 67.6 +/- 8.2 in the occipital lobes, and 53.0 +/- 9.4 in the basal ganglia. Flow was 16.0 +/- 8.4 ml/min/100 g (range 0 to 40.0) in the center of infarcted myocardium and 82.0 +/- 32.0 in the remote segments. This method meets most of the demands for use of microspheres to measure tissue blood flow. The wide range of flow values in infarcted myocardium may be a function of infarct size, spatial resolution, or pathologic evidence of islands of viable tissue. Patients with angina had high flow values in the infarcted segment, whereas those with heart failure had significantly lower values. Surviving myocardium in the region of the infarct may need to be considered if patients complain of angina, particularly when treatment is aimed at preserving ventricular function.
Noninvasive evaluation of aortic regurgitation by continuous-wave Doppler echocardiography.
Authors: Masuyama T , Kodama K , Kitabatake A , Nanto S , Sato H , Uematsu M , Inoue M , Kamada T
Published: June 2011

Continuous-wave Doppler echocardiography was used to examine the aortic regurgitant flow velocity pattern in 32 patients with aortic regurgitation (AR) and 10 patients without AR. The aortic regurgitant flow velocity patterns, characterized by a rapid rise in flow velocity immediately after closure of the aortic valve, high peak flow velocity, and a gradual deceleration until the next aortic valve opening, were successfully obtained in 30 of the 32 patients with AR (sensitivity 94%, specificity 100%). The velocity decline was greater in patients with severe AR; thus, the slope of the velocity decline (deceleration) and the time to decline to half the peak velocity (half-time index) were measured from the flow velocity pattern. The deceleration became greater and the half-time index shortened in accordance with angiographic grading of AR (p less than .01). The deceleration and the half-time index also correlated well with the aortic regurgitant fraction (r = .79, p less than .01; r = -.89, p less than .01). Because the half-time index could be measured easily and independently of Doppler incident angle, it seemed a simple and accurate index of assessing the severity of AR. Thus continuous-wave Doppler echocardiography permitted the noninvasive evaluation of AR.
Premortem assessment of myocardial area at risk with the use of intracoronary technetium macroaggregated albumin and gated nuclear imaging.
Authors: Feiring A J , Bruch P , Husayni T S , Kirchner P T , Marcus M L
Published: June 2011

The purpose of this study was to develop a clinically applicable system for quantifying premortem myocardial area at risk. Coronary artery occlusion was performed in 18 closed-chest dogs (11 left anterior descending and seven circumflex). 99mTc (15 mCi)-labeled macroaggregated albumin was then injected through an angiographic catheter into the left main coronary artery. Gated nuclear images were obtained in the left anterior oblique view in dogs with left anterior descending occlusions and in right anterior oblique views in dogs with circumflex artery occlusions. The corresponding end-diastolic images were analyzed. The percent area at risk was determined as the planimetric ratio between the hypoperfused area and that of the total left ventricular myocardium. At the completion of the study the heart was excised and the autoradiographic area at risk for the left ventricle was determined. The theoretic advantage of the use of gated acquisition for determination of area at risk over the use of nongated acquisition was assessed. For each study a time-integrated nongated image was produced by summating all frames of the gated study. The area at risk on this composite image was analyzed in the same manner as for the gated study and compared with the postmortem area at risk. Studies in five control dogs in which concomitant left atrial and intracoronary injection of different radioactive-labeled macroaggregates were used revealed no false-positive defects and similar and relatively homogenous radionuclide distribution. Postmortem autoradiographic area at risk ranged from 3.8% to 36.3% of the left ventricular mass. End-diastolic areas at risk in vivo correlated well with those determined by the postmortem autoradiographic method (r = .95, y = 0.86x + 2.7). The regression equations relating interobserver and intraobserver variance for analysis of the end-diastolic image areas at risk were small (r = .98, y = 1.06x - 0.66 and r = .96, y = 1.06x - 0.50, respectively). The interobserver and intraobserver differences for determinations of autoradiographic area at risk were represented by r = .99, y = 1.04x - 0.54 and r = .95, y = 0.88x + 2.79. Finally, comparison of the area at risk in vivo for the nongated image with the postmortem area at risk yielded a correlation of r = .79, y = 0.80x - 2.2. Nongated imaging was less sensitive and accurate than gated imaging and resulted in three false-negative studies, as well as a poorer correlation with results of postmortem autoradiography.(ABSTRACT TRUNCATED AT 400 WORDS)