bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of resting left ventricular function on the left ventricular response to exercise in patients with coronary artery disease.
Authors: Port S , McEwan P , Cobb F R , Jones R H
Published: June 2011

First-pass radionuclide angiocardiography was used to access the left ventricular response to submaximal exercise in 150 patients with coronary artery disease (CAD). To test the hypothesis that resting systolic left ventricular function as determined by left ventricular ejection fraction (LVEF) was a predictor of the hemodynamic response to exercise, the study group included patients with a wide range of resting LVEF (0.12-0.82). The influences of resting LVEF, resting end-diastolic volume, the number of diseased vessels, exercise end point and exercise double product on the change in LVEF (delta LVEF) during exercise were tested using multiple linear regression analyses. Resting LVEF was a highly significant predictor of the delta LVEF (p = 0.0001). Exercise duration was not related to either the resting LVEF or the delta LVEF. For the 112 patients in whom coronary anatomy was known, resting LVEF retained its significance as a predictor of delta LVEF (p = 0.002) even after adjustment for the significance of the extent of CAD (p = 0.0007) and the exercise end point (p = 0.06). Patients with normal resting LVEF showed the most profound decreases in LVEF, the highest frequency of new regional dysfunction and the largest relative increase in end-diastolic volume during exercise. As rest LVEF decreased, the magnitude of the delta LVEF and the frequency of new regional dysfunction decreased. Therefore, left ventricular function at rest is an important determinant of the direction and magnitude of change in left ventricular function during exercise.
Application of information theory to clinical diagnostic testing. The electrocardiographic stress test.
Authors: Diamond G A , Hirsch M , Forrester J S , Staniloff H M , Vas R , Halpern S W , Swan H J
Published: June 2011

The inherent imperfection of clinical diagnostic tests introduces uncertainty into their interpretation. The magnitude of diagnostic uncertainty after any test may be quantified by information theory. THe information content of the electrocardiographic ST-segment response to exercise, relative to the diagnosis of angiographic coronary artery disease, was determined using literature-based pooled estimates of the true- and false-positive rates for various magnitudes of ST depression from less than 0.5 mm to greater than or equal to 2.5 mm. This analysis allows three conclusions of clinical relevance. First, the diagnostic information content of exercise-induced ST-segment depression, interpreted by the standard 1.0-mm criterion, averages only 15% of that of coronary angiography. Second, there is a 41% increase in information content when the specific magnitude of ST-segment depression is analyzed, as opposed to the single, categorical 1-mm criterion. Third, the information obtained from ECG stress testing is markedly influenced by the prevalence of disease in the population tested, being low in the asymptomatic and typical angina groups and substantially greater in groups with nonanginal chest pain and atypical angina. The quantitation of information has broad relevance to selection and use of diagnostic tests, because one can analyze objectively the value of different interpretation criteria, compare one test with another and evaluate the cost-effectiveness of both a single test and potential testing combination.
Radionuclide assessment of peripheral intravascular capacity: a technique to measure intravascular volume changes in the capacitance circulation in man.
Authors: Rutlen D L , Wackers F J , Zaret B L
Published: June 2011

Changes in the capacitance vasculature influence venous return and cardiac performance, so an understanding of the effects of pathophysiologic states on the human capacitance vasculature is necessary to understand integrated cardiovascular function in man. Techniques available to assess the capacitance vasculature in man, however, have limitations. We performed radionuclide imaging of the calf or forearm in 51 patients whose erythrocytes had been labeled in vivo with technetium-99m, basing our approach on the principle that counts from the radiolabeled intravascular space are proportional to blood volume. Two-minute or 15 second count acquisitions were obtained from the calf in 42 patients. Counts obtained at rest demonstrated little variation. With veno-occlusion at 15 and 30 mm Hg, counts increased 8 +/- 1% (+/- SEM) (p less than 0.001) and 28 +/- 2% (p less than 0.001), respectively. After 0.4 mg of sublingual nitroglycerin, counts increased 9 +/- 1% (p less than 0.001). With leg elevation, counts decreased 34 +/- 4% (p less than 0.001). Response patterns were similar with 2-minute and 15-second acquisitions. In nine patients who underwent forearm imaging (2-minute acquisitions), counts increased 14 +/- 2% (p less than 0.001) and 26 +/- 4% (p less than 0.001) at 15- and 30-mm Hg veno-occlusion and 15 +/- 3% (p less than 0.001) after nitroglycerin. Volume displacements, recorded simultaneously with a fluid-filled plethysmograph about the contralateral forearm, correlated linearly in all nine patients. Thus, gamma camera imaging of the radiolabeled peripheral intravascular space provides a quantitative and reliable assessment of peripheral vascular capacity in man. The technique could be used in conjunction with gated cardiac imaging in order to assess the interactions of peripheral vascular capacity and ventricular performance.
Comparison of resection versus patch aortoplasty for repair of coarctation in infants and children.
Authors: Hesslein P S , McNamara D G , Morriss M J , Hallman G L , Cooley D A
Published: June 2011

To evaluate two surgical techniques of treatment for coarctation of the aorta in infants and children, we retrospectively compared our long-term experience with resection and end-to-end anastomosis ("resection") vs Dacron patch aortoplasty in patients operated upon when younger than 16 years of age. Since 1967, 184 patients underwent either resection (n = 96) or patch aortoplasty (n = 88). These groups were comparable in terms of preoperative systolic blood pressure, systolic pressure gradient across the coarctation, the year of operation, age and weight at operation, prevalence of associated cardiovascular defects, and duration of postoperative clinical follow-up (1-12.3 years, median 4.3 years). There was no statistically significant difference in operative mortality between surgical groups. Among 104 patients with follow-up longer than 1 year, there was no statistically significant difference between the two operations in the appearance of a residual gradient greater than 10 mm Hg, but for both groups this degree of residual gradient was more frequent in infants (22 of 43, 51%) than in older children (18 of 61, 31%; p less than 0.025). Late postoperative systolic hypertension was noted in 20 of 104 patients (19%), divided equally between the two operative groups. Most late hypertensive patients (13 of 20, 65%) also had residual coarctation; otherwise, the occurrence of postoperative hypertension was not influenced by the type of repair or age at repair. We conclude that resection and patch aortoplasty are equivalent operations for coarctation of the aorta in infants and children, and that long-term relief of gradient is related to age at operation rather than to technique of repair.
Effects of oral disopyramide phosphate on induction of paroxysmal supraventricular tachycardia.
Authors: Swiryn S , Bauernfeind R A , Wyndham C R , Dhingra R C , Palileo E , Strasberg B , Rosen K M
Published: June 2011

The effects of oral disopyramide phosphate on laboratory induction of paroxysmal supraventricular tachycardia (PSVT) were studied in 16 patients with clinical PSVT. After control electrophysiologic study to determine the inducibility and mechanism of PSVT, patients were given 200-300 mg (275 +/- 45 mg, mean +/- SD) of disopyramide for three to five doses over 24 hours and were then restudied. All patients had inducible, sustained PSVT during the control study. After disopyramide, PSVT was noninducible in eight patients (50%), including six of nine with atrioventricular nodal reentrance and two of seven with atrioventricular reentrance; inducible but nonsustained in two (12.5%) (both with atrioventricular reentrance); and inducible and sustained in six (37.5%). The benefit of disopyramide seemed predominantly to reflect depression of conduction in the retrograde limb of the circus movements, although effects upon the antegrade limb were also observed. In the eight patients with inducible PSVT before and after disopyramide, tachycardia cycle length increased from 348 +/- 33 to 404 +/- 29 msec (mean +/- SEM) (p less than 0.001). These results suggest that disopyramide would be effective in preventing recurrence of clinical PSVT in selected patients.
Clinical pharmacology and antiarrhythmic efficacy of encainide in patients with chronic ventricular arrhythmias.
Authors: Winkle R A , Peters F , Kates R E , Tucker C , Harrison D C
Published: June 2011

We determined the pharmacokinetics, efficacy and therapeutic plasma concentration of encainide, a new antiarrhythmic drug that affects His-Purkinje conduction but not ventricular refractoriness. Nine patients with frequent and complex premature ventricular complexes were studied in a 3-day double-blind protocol. Each day, each patient received 75 mg of i.v. or oral encainide or placebo. Frequent blood samples for encainide plasma concentration determination and continuous ambulatory ECGs were obtained. There was a marked intersubject variation in bioavailability (mean 42 +/- 24%, range 7.4-82%), clearance (13.2 +/- 5.6 ml/min/kg, range 3.75-22.1 ml/min/kg) and half-life (3.4 +/- 1.7 hours i.v., 2.5 +/- 0.8 hours oral). Eight of nine patients had more than 90% suppression of premature ventricular complexes for 3-36 hours. Minimal antiarrhythmic plasma concentration was higher (39 +/- 54 ng/ml, range 3.5-170 ng/ml) after i.v. dosing than after oral dosing (14 +/- 16 ng/ml, range 1.5-48 ng/ml), suggesting an active metabolite after oral dosing in many patients. Minimal side effects were seen despite high peak plasma concentrations (range 794-1556 ng/ml i.v., 36-495 ng/ml oral). The minimal ratio of toxic to therapeutic plasma concentration ranged from 4.3-326 (median 23) after oral dosing. Antiarrhythmic action was associated with an 11-44% widening of the QRS complex that was not associated with other adverse effects. We conclude that encainide effectively suppresses ventricular arrhythmias. Despite a variable bioavailability, high clearance and short half-life, its wide ratio of toxic to therapeutic concentration and probable active metabolite permit a long duration of action, which should allow a reasonable dose schedule in most patients during chronic oral dosing.
Obesity and cardiac function.
Authors: de Divitiis O , Fazio S , Petitto M , Maddalena G , Contaldo F , Mancini M
Published: June 2011

We studied 10 obese volunteers, mean age 36.5 +/- 10.3 years, who weighed 123.56 +/- 28.7 g and were 69.96 +/- 22.5 kg overweight. The subjects did not have diabetes, arterial hypertension or signs of cardiac and respiratory failure or disease and all underwent right- and left-heart catheterization. cardiac output and stroke volume were high, according to increased oxygen consumption and to the degree of obesity. Ventricular end-diastolic and atrial pressures ranged from normal to high and correlated with body weight, signs of volume overloading and reduced left ventricular (LV) compliance. The mean pulmonary artery pressure was elevated and correlated well with weight, pulmonary resistance being normal; mean aortic pressure did not correlate with weight, and systemic arterial resistance tended to have a negative correlation. The LV function curve showed impaired ventricular function, particularly for the heaviest subjects, in whom Vmax and the ratio of the stroke work index to LV end-diastolic pressure were reduced. These indexes correlated well with each other and both correlated negatively with the degree of obesity. In contrast, maximal dP/dt was normal and did not correlate with excess weight. These observations show that depressed LV function is already present in relatively young obese people, even if they are free from signs of cardiopathy and other associate diseases. The degree of impairment of heart function seems to parallel the degree of obesity.
Reat-time inferior vena caval ultrasonography: normal and abnormal findings and its use in assessing right-heart function.
Authors: Mintz G S , Kotler M N , Parry W R , Iskandrian A S , Kane S A
Published: June 2011

We studied the inferior vena cava (IVC) as an index of right-heart function in 111 patients. A two-dimensional echocardiographic sector was used to visualize the IVC, and its M-mode cursor was used to generate a time-motion record of the IVC size and pulsation. Normal subjects had a small presystolic A wave (less than 125% of the end-diastolic IVC dimension), a small systolic V wave (less than 140% of the end-diastolic IVC dimension), and a 50% inspiratory decrease in IVC dimension. The A wave was absent in patients with atrial fibrillation. When normalized for body surface area, mean end-diastolic IVC dimension correlated with mean right atrial pressure (r = 0.72, p less than 0.001). An A wave greater than or equal to 125% of end-diastolic IVC dimension was recorded in 71% of patients with sinus rhythm and an elevated right ventricular end-diastolic pressure of 10 mm Hg or greater, but in no patient with right ventricular end-diastolic pressure of less than 10 mm Hg (p less than 0.001). A V wave greater than or equal to 140% of end-diastolic IVC dimension was recorded in 75% of patients with severe tricuspid insufficiency, but in no patient with mild or no tricuspid insufficiency (p less than 0.001). The inspiratory decrease in IVC dimension correlated with radionuclide right ventricular ejection fraction (r = 0.75, p less than 0.001); no respiratory variation in end-diastolic IVC dimension occurred in patients with significant right ventricular dysfunction (right ventricular ejection less than 25%) or in patients with constrictive pericarditis.
Pulmonary vascular disease with congenital heart lesions: pathologic features and causes.
Authors: Hoffman J I , Rudolph A M , Heymann M A
Published: June 2011

Pulmonary vascular disease, a serious complication of many congenital heart lesions, has three major components: increased muscularity of small pulmonary arteries; intimal hyperplasia, scarring and thrombosis; and reduced numbers of intraacinar arteries. The muscularity is due to increased stress on the vessel wall, and is reversible. The intimal changes may be due to endothelial damage, causing an imbalance between prostacyclin and thromboxane A2 production and leading to local platelet aggregation. This, in turn, may stimulate migration and division of myointimal cells, which thicken the intima and lead to scarring and thrombosis. Extensive intimal changes are probably irreversible, but the possibility of preventing them by use of agents that inhibit platelet aggregation needs to be considered. The mechanism of a decrease in numbers of intraacinar arteries is unexplained. The potential for growth of new vessels after corrective surgery of the cardiac defect is an important factor in restoring pulmonary vascular resistance to normal. Available evidence suggests that this growth potential is reduced after 2 years of age and argues for early surgical relief of pulmonary vascular stresses.
Etiology, warning signs and therapy of torsade de pointes. A study of 10 patients.
Authors: Keren A , Tzivoni D , Gavish D , Levi J , Gottlieb S , Benhorin J , Stern S
Published: June 2011

Torsade de pointes, also called atypical ventricular tachycardia (AVT), was diagnosed in 10 patients, nine on antiarrhythmic therapy and one with acute central nervous system damage. Four patients received quinidine and five disopyramide, either alone or in combination with amiodarone. AVT was dose-dependent in some, but in others, it started shortly after initiation of drug therapy (idiosyncrasy). All patients had QT prolongation longer than 0.60 second immediately before the onset of AVT. This measurement appeared to be a more sensitive predictor of the development of AVT than QTc prolongation or QRS widening. All patients also showed bradycardia before AVT onset. After therapy, the QT immediately decreased, while QTc and QRS remained prolonged for longer periods. Isoproterenol was effective in five of seven patients, but was contraindicated in two others. Ventricular pacing was used in four patients, including the two who did not respond to isoproterenol, and this abolished AVT promptly. Isoproterenol or pacing appear to be the therapy of choice for AVT, while the conventional drugs used to treat the usual form of ventricular tachycardia are not only ineffective, but even contraindicated.
Comparative reproducibility and validity of systems for assessing cardiovascular functional class: advantages of a new specific activity scale.
Authors: Goldman L , Hashimoto B , Cook E F , Loscalzo A
Published: June 2011

Reproducibility and validity are prerequisites for a useful clinical scale. We therefore prospectively tested the reproducibility and validity of the New York Heart Association criteria and the Canadian Cardiovascular Society criteria for the assessment of cardiac functional class and compared these criteria with a new Specific Activity Scale based on the metabolic costs of specific activities. The New York Heart Association estimates made by two physicians had a reproducibility of only 56%, and only 51% of the estimates agreed with treadmill exercise performance. Functional estimates based on the Canadian Cardiovascular Society criteria were significantly more reproducible (73%), but not significantly more valid. The Specific Activity Scale was as reproducible as the Canadian Cardiovascular Society criteria, and its 68% validity was significantly higher than the validities of the other systems. The easily administered Specific Activity Scale was equally reproducible and valid when used by a nonphysician. It was especially better than the other systems for the evaluation of true class II patients and was significantly less likely to underestimate treadmill performance. Although no set of questions can perfectly predict exercise tolerance, the Specific Activity Scale deserves wider prospective testing.
Hypertrophic cardiomyopathy in infants: clinical features and natural history.
Authors: Maron B J , Tajik A J , Ruttenberg H D , Graham T P , Atwood G F , Victorica B E , Lie J T , Roberts W C
Published: June 2011

The clinical and morphologic features of hypertrophic cardiomyopathy in 20 patients recognized as having cardiac disease in the first year of life are described. Fourteen of these 20 infants were initially suspected of having heart disease solely because a heart murmur was identified. However, the infants showed a variety of clinical findings, including signs of marked congestive heart failure (in the presence of non-dilated ventricular cavities and normal or increased left ventricular contractility) and substantial cardiac enlargement on chest radiograph. Other findings were markedly different from those usually present in older children and adults with hypertrophic cardiomyopathy (e.g., right ventricular hypertrophy on the ECG and cyanosis). Consequently, in 14 infants, the initial clinical diagnosis was congenital cardiac malformation other than hypertrophic cardiomyopathy. Twelve of the 14 infants who underwent left-heart catheterization showed substantial obstruction to left ventricular outflow (peak systolic pressure gradient greater than or equal to 35 mm Hg). However, unlike older patients with hypertrophic cardiomyopathy, infants with this condition commonly had marked obstruction to right ventricular outflow (35-106 mm Hg) (nine patients); in six patients, the magnitude of obstruction to right ventricular outflow was at least as great as that to left ventricular outflow. Asymmetric hypertrophy of the ventricular septum relative to the left ventricular free wall was present in the 16 patients who had echocardiographic or necropsy examination. Ventricular septal thickening was substantial in patients studied both before and after 6 months of age (mean 16 mm), indicating that in patients with hypertrophic cardiomyopathy, marked left ventricular hypertrophy may be present early in life and is probably congenital. The clinical course was variable in these patients, but the onset of marked congestive heart failure in the first year of life appeared to be an unfavorable prognostic sign; nine of the 11 infants with congestive heart failure died within the first year of life. In infants with hypertrophic cardiomyopathy, unlike older children and adults with this condition, sudden death was less common (two patients) than death due to progressive congestive heart failure.
Morphologic evidence for coronary artery spasm in eclampsia.
Authors: Bauer T W , Moore G W , Hutchins G M
Published: June 2011

Vascular spasm has been considered to be an important component of the eclamptic state. If this abnormal vascular reactivity affects the coronary arteries in eclampsia, one might expect to find areas of myocardial contraction band necrosis, a lesion secondary to coronary reflow after periods of no flow. We reviewed the cardiac findings in the 34 patients with fatal eclampsia (hypertension, edema, proteinuria, and convulsions without evident cause) autopsied at The Johns Hopkins Hospital since 1899, and compared each with the next pregnant or puerperal nontoxemic autopsied patient. The eclamptic patients were 15-45 years old (average 27 years). Convulsions began antepartum in 21 patients, intrapartum in eight, and postpartum in five. The hearts weighed 200-407 g (average 312 g). One heart had rheumatic valvular disease and one had myocarditis. Histologic study of heart sections showed the presence of contraction band necrosis in 12 cases (35%). The control cases included two patients with rheumatic valvular disease, two with endocarditis, two with myocarditis, two with pericarditis, and one with leukemic infiltration. Only one control patient (3%) had contraction band necrosis (p less than 0.001). The frequent occurrence of myocardial contraction band necrosis suggests that coronary artery spasm may be common in patients who die with eclampsia.
Acceleration of the ventricular response during atrial fibrillation in the Wolff-Parkinson-White syndrome after verapamil.
Authors: Gulamhusein S , Ko P , Carruthers S G , Klein G J
Published: June 2011

We examined the electrophysiologic effects of verapamil in eight patients with the Wolff-Parkinson-White syndrome. Verapamil shortened the antegrade effective refractory period of the accessory pathway in three patients and abbreviated the shortest cycle length with 1:1 conduction over the accessory pathway in two patients. More significantly, verapamil decreased the shortest RR interval between preexcited ventricular complexes during atrial fibrillation (279 +/- 20 msec vs 236 +/- 18 msec, mean +/- SEM; p less than 0.01). After verapamil, two patients required cardioversion for hemodynamic deterioration after acceleration of the ventricular response during atrial fibrillation. In the four patients with predominantly preexcited ventricular complexes during atrial fibrillation the ventricular rate accelerated after verapamil, whereas in patients with predominantly normal ventricular complexes, the average ventricular rate decreased or did not change after verapamil. Verapamil may result in significant acceleration of ventricular response during atrial fibrillation in the Wolff-Parkinson-White syndrome. The safety of verapamil in individual patients with the Wolff-Parkinson-White syndrome should be established by electrophysiologic testing before its use.
Changes in plasma lipid and lipoprotein levels in men and women after a program of moderate exercise.
Authors: Brownell K D , Bachorik P S , Ayerle R S
Published: June 2011

Levels of high-density lipoprotein (HDL) cholesterol and other lipids and lipoproteins of 24 men and 37 women were measured before and after a 10-week exercise program. The program involved three sessions of aerobic exercise each week, with 15-20 minutes of activity at 70% of maximal heart rate. Men and women had significantly different lipid patterns in response to exercise, despite equivalent increases in maximal oxygen uptake. Men showed a 5.1% increase in HDL cholesterol, a 6% decrease in low-density lipoprotein (LDL) cholesterol, and a 12.4% increase in the HDL/LDL ratio. In contrast, women showed a 1% decrease in HDL cholesterol, a 4.3% decrease in LDL cholesterol, and no significant change in HDL/LDL ratio. The number of sessions attended correlated positively with HDL/LDL changes in men and correlated negatively with HDL/LDL changes in women. These findings suggest that moderate exercise may have different effects on men and women.
A comparison of the acute and long-term hemodynamic effects of ventricular inhibited and atrial synchronous ventricular inhibited pacing.
Authors: Kruse I , Arnman K , Conradson T B , Rydén L
Published: June 2011

Sixteen patients treated with a noninvasively programmable pacemaker were examined after a prolonged period of ventricular inhibited (VVI) and atrial synchronous ventricular inhibited (VDD) pacing. Maximal working capacity was determined by bicycle ergometry. Atrial and ventricular rates, brachial artery cuff pressure and breathing rate were determined at rest and during exercise. There was a mean increase in working capacity of 24% with VDD compared with VVI pacing (p less than 0.001). Thirteen of the patients were catheterized. During VDD pacing, cardiac output was significantly higher, particularly during exercise (+/- 32%) due to the capability of heart rate increase and despite a substantial compensatory stroke volume increase during VVI pacing. Arteriovenous oxygen difference was much higher during VVI pacing, reaching 164 +/- 14 ml/l during the highest work load, while the corresponding level during VDD pacing was 140 +/- 14 ml/l (p less than 0.001). During exercise, arterial blood lactate was significantly higher during VVI than during VDD pacing. Heart size was significantly smaller, 568 +/- 98 vs 530 +/- 96 ml/m2 BSA (p less than 0.05), during VDD pacing a questionnaire was completed by the patients to evaluate subjective symptoms and pacemaker preference. This part of the study favored the VDD mode of pacing. The conclusion of this study is that VDD pacing is superior to VVI pacing.
Different reactivity and structure of the prestenotic and poststenotic aorta in human coarctation. Implications for baroreceptor function.
Authors: Sehested J , Baandrup U , Mikkelsen E
Published: June 2011

In eight humans with coarctation, fresh aortic tissue was examined pharmacodynamically. In four of these patients, and in 12 additional patients, the aorta above and below the coarctation was studied morphologically and compared with eight control aortas. By in vitro stimulation with potassium (127 mM), noradrenaline (18 microM), and prostaglandin F2 alpha (28 microM), postcoarctational aortic ring preparations showed a significantly greater contractility than precoarctational rings (p less than 0.05). Volumetric analysis showed significantly more collagen (P less than 0.01) and les smooth muscle mass (p less than 0.01) in the aorta above than below the coarctation. No significant differences were found between sections from the arch and distal to the ligamentum arteriosum in the normal aortas. We conclude that the precoarctational aortic wall is more rigid than the postcoarctational wall. This may influence baroreceptors in the upper vascular bed in such a way as to tolerate a higher pressure. This would explain the preoperative proximal hypertension, the paradoxic hypertension and the frequent lack of normalization of blood pressure postoperatively.
Comparison of intravenous nitroglycerin and sodium nitroprusside for treatment of acute hypertension developing after coronary artery bypass surgery.
Authors: Flaherty J T , Magee P A , Gardner T L , Potter A , MacAllister N P
Published: June 2011

The present study was designed to test the hypothesis that i.v. nitroglycerin is as effective as sodium nitroprusside for managing acute hypertension early after coronary artery bypass surgery. Seventeen patients received both nitroglycerin and nitroprusside in a randomized crossover protocol. Infusion rates were increased stepwise to lower mean arterial pressures comparably with each drug. In 14 of 17 patients, similar infusion rates of the two vasodilators resulted in equal lowering of both blood pressure and systemic vascular resistance. In the remaining three patients, very high infusion rates of nitroglycerin were required and achieved only 20-50% of nitroprusside's response in two of three. Hemodynamic responses to the two vasodilators were similar, except that nitroglycerin increased cardiac output more than nitroprusside did. In contrast, pulmonary gas exchange responses differed in that nitroglycerin improved intrapulmonary shunting, while nitroprusside worsened it. Similarly, nitroglycerin resulted in a significantly smaller increase in the alveolar arterial oxygen gradient than did nitroprusside. These results suggest that in the majority of patients, i.v. nitroglycerin was as effective as nitroprusside in controlling acute hypertension after coronary artery bypass surgery. In addition, nitroglycerin appeared to have more favorable effects on pulmonary gas exchange. Because nitroglycerin has more beneficial effects on intercoronary collateral blood flow in the setting of regional ischemia, it may be preferable to nitroprusside in patients with ischemic heart disease.
Acute hemodynamic effects of nifedipine in patients with ischemic heart disease.
Authors: Majid P A , De Jong J
Published: June 2011

We studied the acute hemodynamic effects of nifedipine in 20 patients with angiographically proved coronary artery disease. Eight patients were studied during exercise-induced pain. There was an expected abnormal increase in pulmonary wedge pressure (28 +/- 8 mm Hg, mean +/- SD) accompanying chest pain (onset 179 seconds, duration 334 seconds) and ST-segment depression (2.2 +/- 0.9 mm) on the ECG. Pacing stress was used in six patients and increased left ventricular (LV) end-diastolic pressure (from 16 +/- 6 to 26 +/- 6 mm Hg), volumes (end-diastolic 63 +/- 20 to 81 +/- 22 ml/m2, end-systolic 26 +/- 15 to 47 +/- 16 ml/m2) and impaired ejection fraction (0.60 +/- 0.15 to 0.44 +/- 0.11) compared with control values. In both groups, nifedipine, 20 mg sublingually, significantly shortened duration of pain, reduced ST depression on the ECG (p less than 0.001) and reversed all hemodynamic abnormalities. In another group of six patients with recent (less than 4 months) acute myocardial infarction and moderately severe LV dysfunction at rest, nifedipine reduced LV end-diastolic pressure from 21 +/- 6 to 12 +/- 5 mm Hg and volumes (end-diastolic from 109 +/- 35 to 95 +/- 32 ml/m2, end-systolic from 41 +/- 15 to 31 +/- 7 ml/m2), while the ejection fraction improved significantly, from 0.43 +/- 0.08 to 0.58 +/- 0.11. Thus, the antianginal effect of nifedipine is associated with improved systolic emptying and reduced diastolic filling of the heart. Nifedipine appears to have no discernible adverse effects in patients with depressed LV function.
Myocardial free-wall rupture after acute infarction: survival aided by percutaneous intraaortic balloon counterpulsation.
Authors: Hochreiter C , Goldstein J , Borer J S , Tyberg T , Goldberg H L , Subramanian V , Rosenfeld I
Published: June 2011

After his first acute myocardial infarction, a 69-year-old male suffered the usually lethal complication of ventricular free-wall rupture. Early suspicion of possible rupture and immediate percutaneous insertion of an intraaortic balloon pump assist device afforded sufficient hemodynamic stability to proceed with cardiac catheterization. The diagnosis of ventricular free-wall rupture was confirmed and the extent of coronary artery disease defined. The patient underwent repair of the free-wall rupture and coronary artery bypass grafting and has returned to full activity.
Employment status after coronary artery bypass surgery.
Authors: Oberman A , Wayne J B , Kouchoukos N T , Charles E D , Russell R O , Rogers W J
Published: June 2011

With a few exceptions, prevailing data on return to work after coronary artery bypass surgery indicate no net gain in employment status for at least several years after the operation. Despite the improved surgical experience and advances in the medical management of postoperative patients, only limited employment benefits occur after surgery, and no gains in work rehabilitation over the past decade have been noted. Several characteristics--preoperative work status, nonwork income, occupation, relief of symptoms, age, perception of health, education and severity of disease--appear to be important for estimating the likelihood of employment after surgery. Other influences, such as attitudes of the family, employers and physicians, undoubtedly alter the probability of return to the work force, but are less well documented. Unless constructive approaches toward work rehabilitation are made, the possibility of return to gainful employment should not be considered an indication for or a necessary consequence of coronary artery bypass surgery.
Hemodynamics, biochemical and reflexive changes produced by atenolol in hypertension.
Authors: Dreslinski G R , Messerli F H , Dunn F G , Suarez D H , Reisin E , Frohlich E D
Published: June 2011

Hemodynamic (systemic and regional), metabolic and cardiovascular reflexive variables were measured before and after 4 weeks of beta blockade with atenolol in 10 patients with mild essential hypertension. Atenolol reduced mean arterial pressure, heart rate, cardiac index (all p less than 0.005) and renal vascular resistance (p less than 0.01) and increased total peripheral resistance (p less than 0.005). Glomerular filtration rate and renal blood flow were unchanged; plasma renin activity fell 43%. Reflexive cardioacceleration during the Valsalva maneuver and upright passive tilt was blunted. No changes were observed in circulating fluid volumes. In six patients followed for 1 year, blood pressure and heart rate were maintained at levels similar to those during the first 4 weeks. Atenolol was shown to be an effective oral antihypertensive that has no apparent deleterious hemodynamic effects on the renal and splanchnic circulations.
Detection of left ventricular thrombus by two-dimensional echocardiography: sensitivity, specificity, and causes of uncertainty.
Authors: Stratton J R , Lighty G W , Pearlman A S , Ritchie J L
Published: June 2011

To define the sensitivity, specificity and predictive accuracy of two-dimensional echocardiographic detection of left ventricular thrombus, the echocardiograms of 78 patients who had independent proof of the presence or absence of a left ventricular thrombus were interpreted without knowledge of any clinical data. The presence of thrombus was established by autopsy in four patients, by aneurysmectomy in three, and by indium-111 platelet imaging in 15; the absence of thrombus was proved by autopsy in 55 patients and by aneurysmectomy in one patient. The characteristics of true-positive and false-positive echocardiograms, interobserver variability, and clinical features associated with proved thrombus were also defined. The echocardiogram was positive for thrombus in 22 patients, equivocal in seven and negative in 49. For detection of thrombus, a positive or equivocal echocardiogram had a sensitivity of 95% (21 of 22), a specificity of 86% (48 of 56), and a predictive value of 72% (21 of 29); the predictive value of a negative study was 98% (48 of 49). Considering positive and equivocal studies separately, the predictive value of a positive study was 86% (19 of 22), while that of an equivocal study was only 29% (two of seven). Compared with patients who had no thrombus, patients with proved thrombus had a higher prevalence of electrocardiographic transmural anterior infarction (86% vs 13%), left ventricular aneurysm (73% vs 5%), and clinical systemic emboli (36% vs 7%) (all p less than 0.05). These clinical features help to identify a subset of patients most likely to have left ventricular thrombi who may benefit from echocardiography. Two-dimensional echocardiography is highly sensitive in detecting left ventricular thrombus, but false-positive studies are relatively common. Several echocardiographic criteria derived from analysis of the true and false positives in this study may help minimize diagnostic errors.
Platelet release and thromboxane synthesis in symptomatic coronary artery disease.
Authors: de Boer A C , Turpie A G , Butt R W , Johnston R V , Genton E
Published: June 2011

The incidence and significance of platelet activation in myocardial ischemia was evaluated by serial measurement of plasma thromboxane B2 (TXB2) and beta thromboglobulin (beta TG) in plasma and urine in 98 patients admitted to a coronary care unit with chest pain. All measurements were normal in the 26 patients with noncardiac chest pain. Mean plasma TXB2 and beta TG concentration, but not urine beta TG, were elevated in the 25 patients with myocardial infarction and the 47 patients with angina. The beta TG levels remained normal in 61% of the patients with angina or infarction. The TXB2 levels were significantly higher in patients with recurrent episodes of angina at rest than in those without ischemic episodes after admission. There was a weak correlation between plasma TXB2 and plasma beta TG (r = 0.20, p less than 0.01) and between plasma and urine beta TG (r = 0.31, p less than 0.01). Results indicate that platelets are frequently activated with myocardial ischemia or infarction. However, the measurement of beta TG and TXB2 is of limited value in detecting or differentiating myocardial ischemia from infarction and therefore lacks clinical value in the management of patients with ischemic heart disease.
The QT interval throughout the first 6 months of life: a prospective study.
Authors: Schwartz P J , Montemerlo M , Facchini M , Salice P , Rosti D , Poggio G , Giorgetti R
Published: June 2011

A prospective electrocardiographic study was designed to establish baseline values for electrocardiographic measurements, with specific reference to the QT interval during infancy, and to test the "QT hypothesis" for the sudden infant death syndrome (SIDS). In this ongoing study, ECGs are recorded on the fourth day of life and in the second, fourth and sixth months. The state of health at 1 year is ascertained by a phone call. So far, 4205 newborns have been enrolled. The mean QTc (QT interval corrected for heart rate) was 397 +/- 18 msec (+/- SD) at the fourth day, 409 +/- 15 msec (p less than 0.0001) at the second month, and 406 +/- 15 msec at the fourth month; by the sixth month, it returned to 400 +/- 14 msec. In 88 newborns, the QTc increased by over 40 msec at the second month. Among the 2000 infants checked at 1 year, there have been three sudden and unexpected deaths. The QTc of one of the victims at the fourth day was 563 msec, which exceeded the mean by more than 9 standard deviations, while the QTc of the other SIDS victims exceeded the mean by more than 2 and 3 standard deviations. These results are consistent with the "QT hypothesis," but more data are necessary before any conclusion on the potential relationship between QT interval prolongation and SIDS can be drawn. This study provides definitive waking normal values for QT interval in infancy and indicates that the QT interval lengthens physiologically and temporarily during the first months of life. In some infants, this lengthening may transiently impair cardiac electrical stability.
Indium-111-labeled platelets: effects of heparin on uptake by venous thrombi and relationship to the activated partial thromboplastin time.
Authors: Fedullo P F , Moser K M , Moser K S , Konopka R , Hartman M T
Published: June 2011

The goal of heparin therapy in deep vein thrombosis is to prevent thrombus extension. The relationship between thrombus extension and the results of coagulation tests used to monitor heparin therapy is unclear. To explore this relationship, we studied the effect of several heparin regimens on the accretion of indium-111-labeled platelets on fresh venous thrombi, as detected by gamma imaging, and monitored the activated partial thromboplastin time (APTT). Six dogs were treated with a 300-U/kg bolus of heparin followed by a 90-U/kg/hour heparin infusion, a dose of heparin sufficient to increase the APTT to levels greater than eight times baseline (APTT ratio); platelet accretion (thrombus imaging) occurred only after the heparin effect was reversed with protamine sulfate. Nineteen dogs were treated with a 150-U/kg bolus of heparin followed by a 4-hour, 45-U/kg/hour heparin infusion; a thrombus was demonstrated only after protamine injection in 12 (mean APTT ratio 1.3 +/- 0.19) and before protamine injection in seven. In thirteen of these 19 dogs, 30 minutes separated the platelet injection from heparin therapy, while in six this duration was less than 30 minutes. In four of these six dogs, thrombi were demonstrated before protamine therapy and at APTT ratios greater than 3.0. Finally, 10 dogs were treated with a 100-U/kg bolus followed by a 3-hour, 50-U/kg/hour heparin infusion, after which the APTT was allowed to return to baseline values spontaneously. In all 10 dogs, a thrombus was demonstrated only after cessation of the heparin infusion, and at a mean APTT ratio of 1.4 +/- 0.15 times baseline. These results suggest that, except with very early platelet injection, platelet accretion by thrombi is consistently inhibited by heparin at APTT ratios greater than 2.5. Platelet accretion by venous thrombi occurs within narrow limits of heparin effect as reflected by the APTT.
Intrauterine and postnatal atrial fibrillation in the Wolff-Parkinson-White syndrome.
Authors: Belhassen B , Pauzner D , Blieden L , Sherez J , Zinger A , David M , Muhlbauer B , Laniado S
Published: June 2011

A fetal tachyarrhythmia was discovered at the thirty-second week of gestation of a 22-year old woman. Fetal echocardiography revealed atrial fibrillation with rapid ventricular rate, without any other demonstrable cardiac abnormality. In spite of therapeutic maternal blood levels of digoxin, the fetal ventricular rate and cardiac size increased, which prompted us to perform cesarean section at the thirty-fourth week of gestation. A baby with a Wolff-Parkinson-White syndrome but no other cardiac anomaly was delivered. Recurrent episodes of nonsustained atrial fibrillation with conduction over the accessory pathway occurred in the first hours of life. The Wolff-Parkinson-White pattern was not present on subsequent ECG recordings. The use of echocardiography in the diagnosis and management of this rare fetal tachyarrhythmia is emphasized.
Electrocardiographic localization of coronary artery narrowings: studies during myocardial ischemia and infarction in patients with one-vessel disease.
Authors: Fuchs R M , Achuff S C , Grunwald L , Yin F C , Griffith L S
Published: June 2011

To investigate the accuracy of the 12-lead ECG in localizing the site of coronary artery narrowings, we reviewed abnormal ECGs obtained during myocardial infarction, spontaneous angina or exercise stress testing in 134 patients with angiographically documented one-vessel disease. The presence of Q waves, ST-segment elevation and T-wave inversion in leads I, aVL and V1--V4 were all highly correlated with the presence of left anterior descending coronary artery disease (p less than 0.001), and the same ECG findings in leads II, III and aVF were associated with right (RCA) or circumflex coronary artery (LCx) narrowings (p less than 0.001). In contrast, ST depression alone was not useful in predicting the site of coronary artery narrowing. Q waves correctly identified the location of the coronary disease in 98% of cases, ST elevation in 91%, T-wave inversion in 84%, and ST depression in 60%. No electrocardiographic criteria distinguished RCA from LCx disease, even in patients with a right-dominant circulation. These findings should lead to a better understanding of the value and limitations of the 12-lead ECG in localizing coronary artery disease.
Increased exercise tolerance after nitroglycerin oral spray: a new and effective therapeutic modality in angina pectoris.
Authors: Kimchi A , Lee G , Amsterdam E , Fujii K , Krieg P , Mason D T
Published: June 2011

The prophylactic antianginal efficacy of nitroglycerin (NTG) oral spray was assessed in 20 patients with angiographically documented coronary disease and stable angina pectoris. The evaluation was by a randomized crossover trial involving treadmill exercise testing. On study day 1, a control treadmill exercise test was performed, followed 30 minutes later by a second exercise test 2 minutes after administration of either placebo (group A, 10 patients) or NTG spray 0.8 mg (group B, 10 patients). One week later, on study day 2, the patients again underwent control treadmill exercise testing followed by a second exercise test after either NTG spray (group A) or placebo (group B). NTG spray delayed the onset of anginal pain during exercise by a mean of 100 +/- 64 seconds (p less than 0.001) in 13 patients and prevented pain entirely in seven. Placebo did not significantly delay the appearance of angina and prevented chest pain in only one patient. NTG spray increased treadmill exercise duration by 31% before the onset of angina (p less than 0.001); placebo did not significantly alter the duration of exercise. NTG spray abolished in six patients and delayed in 14 patients the onset of exercise-induced ST-segment depression of 1 mm (p less than 0.001). Patients achieved a higher heart rate at peak exercise with NTG spray, and yet the maximal exercise-induced ST-segment depression of 2.1 +/- 1.0 mm during the control study declined to 1.3 +/- 0.9 mm on NTG spray (p less than 0.001). Placebo had no effect on exercise ST-segment depression. These data indicate that the oral NTG spray is an effective prophylactic for exercise-induced angina.