bluuebunny/crossref_metadata_2025 huggingface dataset:
Labile hypertension: a faulty concept? The Framingham study.
Authors: Kannel W B , Sorlie P , Gordon T
Published: June 2012

Labile blood pressure elevation is believed to have less clinical significance than "fixed hypertension." This assertion was examined in the Framingham cohort of 5209 men and women followed for 20 years for the development of cardiovascular events in relation to three routinely measured blood pressures at each of 10 biennial examinations. Variability of pressure judged from the standard deviation about the mean of three pressures was not a consistent characteristic of subjects from one examination to the next (r = 0.07). Higher pressures were more labile than low ones, so that "fixed hypertensives" actually had more labile pressures than did so-called labile hypertensives. Lability, also increased with age. Labile hypertension, determined during a 1-hour period of observation, adds nothing to the ability of the mean blood pressure to predict cardiovascular disease. The mean, minimum and maximum of three pressures measured during an examination were equally efficient predictors of cardiovascular disease. In multivariate analysis, for any given average pressure, risk of cardiovascular events was unaffected by the degree of variability of the pressure. It is recommended that the average of a series of pressures be used to determine risk, preferably over more than one examination.
Metabolic studies in mitral valve prolapse syndrome. A neuroendocrine--cardiovascular process.
Authors: Boudoulas H , Reynolds J C , Mazzaferri E , Wooley C F
Published: June 2012

Symptomatic patients with mitral valve prolapse (MVP) frequently mimic thyrotoxicosis, hyperadrenergic states or hypoglycemia. Twenty symptomatic patients with auscultatory and echocardiographic MVP were studied in the clinical research unit. T3, T4 and plasma cortisol were normal. Patients with MVP had normal responses to oral glucose administration but higher glucose levels than the controls (p less than 0.05). Twenty-four-hour urinary epinephrine (E) and norepinephrine (NE) were greater than normal (E + NE excretion, 44 +/- 2 vs 29.5 microgram/g creatinine, p less than 0.001). The short electromechanical systole corrected for heart rate (529 +/- 3.9 vs normal 548 +/- 2 msec, p less than 0.01) also reflected high adrenergic tone. Frequent premature ventricular complexes (PVCs) with couplets and triplets were found in 14 patients. Catecholamine excretion and frequency of PVCs were parallel and both decreased significantly at night (p less than 0.001). Plasma catecholamine increase with exercise was greater in patients in whom the number of PVCs increased more than 10 per minute compared with patients in whom the number of PVCs remained relatively unchanged (620 +/- 80 vs 98 +/- 20 msec, p less than 0.01). We conclude that symptomatic patients with MVP have high adrenergic tone that may be responsible for or contribute to the multiple symptoms.
Contractile performance of the hypertrophied ventricle in patients with systemic hypertension.
Authors: Takahashi M , Sasayama S , Kawai C , Kotoura H
Published: June 2012

To assess the contractile state of the hypertrophied ventricle induced by long-standing systemic hypertension in 22 patients, we used echocardiography for the measurement of the ventricular diameter and posterior wall thickness, together with simultaneous recording of brachial arterial pressure. Meridional wall stress (WSt) was used for the expression of the force per unit cross-sectional area. The WSt-diameter relation obtained during dynamic responses to acute pressure reduction by nitroprusside infusion was compared with the same relation obtained in 10 normal subjects (posterior wall thickness averaged 0.7 cm [range 0.6-0.9 cm]) over a range of matched systolic pressure induced by methoxamine administration. In 15 patients in whom end-diastolic wall thickness increased to 1.1 cm (range 1.0-1.2 cm), the linear WSt-diameter relation at end-systole did not differ from the control group, indicating a normal level of inotropic state. In the seven patients with an end-diastolic wall thickness of 1.3 cm or more, the end-systolic WSt-diameter relation was clearly shifted to the right and had a less steep slope. These findings indicate that in advanced left ventricular hypertrophy induced by pressure overload, myocardial contractility may be depressed.
Effects of antiarrhythmic drugs on atrioventricular conduction in patients with acute myocardial infarction.
Authors: Scheinman M M , Remedios P , Cheitlin M D , Peters R W , Holford N , Desai J , Abbott J A
Published: June 2012

Three hundred fifty-eight of 429 (83%) consecutive patients with acute myocardial infarction (MI) and a normal PR interval received various antiarrhythmic drugs (AD), including lidocaine and/or procainamide, quinidine, digoxin, propranolol or disopyramide. There was no significant difference in the incidence of progression to any degree of atrioventricular (AV) block or to higher degrees of AV block (Mobitz II or third-degree AV block) between those treated and not treated with AD: 38 of 358 (11%) and six of 358 (1.7%) with AD vs 11 of 71 (15%) and two of 71 (2.8%) in the untreated group, respectively. Similarly, there was no significant difference in progression between treated and untreated patients with anterior MI, 14 of 144 (10%) vs five of 32 (16%); inferior MI, 21 of 111 (19%) vs five of 26 (19%), or subendocardial MI, three of 103 (3%) vs one of 12 (8%). Bundle branch block (BBB) (without AV block) was initially present in 89 of 249 (21%). The incidence of AV block (seven of 24, 30%) was higher in treated patients with newly acquired BBB (27 patients) than in the untreated patients (none of three, p less than 0.05). The commonly used ADs did not adversely affect AV conduction in patients with acute MI with narrow QRS and either normal, first-degree, or Mobitz I AV block. Moreover, no subset of patients grouped by infarct location, specific AD used, or BBB (except perhaps for those with newly acquired BBB) appeared to be at risk of development of AV block during AD therapy.
Beneficial effects of hydralazine on rest and exercise hemodynamics in patients with chronic severe aortic insufficiency.
Authors: Greenberg B H , DeMots H , Murphy E , Rahimtoola S
Published: June 2012

We studied the effects of afterload reduction in chronic severe aortic insufficiency by measuring the hemodynamic response to oral hydralazine in 10 consecutive patients. Hemodynamics were also measured during maximal exercise in eight of these patients. At rest, hydralazine reduced pulmonary artery wedge pressure from 14 to 9 mm Hg (p less than 0.01), and increased cardiac index by 70% and stroke volume index by 35% (both p less than 0.001). Before hydralazine, pulmonary artery wedge pressure exceeded 20 mm Hg in five patients during maximal exercise; with hydralazine, at identical levels of exercise, pulmonary artery wedge pressure remained below 20 mm Hg in all patients. For the group, hydralazine reduced pulmonary artery wedge pressure from 21 to 12 mm Hg (p less than 0.05) and increased cardiac index by 31% (p less than 0.05) during exercise; changes in stroke volume index were more variable and there was no significant increase for the group, although several patients increased stroke volume substantially and the overall increase was 34%. These data show that afterload reduction has beneficial effects on cardiac performance in chronic severe aortic insufficiency both at rest and during exercise. Hydralazine may be of use in such patients either in preparation for valve replacement or as interim therapy.
Cardiorespiratory responses of cardiac transplant patients to graded, symptom-limited exercise.
Authors: Savin W M , Haskell W L , Schroeder J S , Stinson E B
Published: June 2012

The electrocardiographic and ventilatory responses of 15 denervated heart patients who had undergone cardiac transplantation and 14 age-matched, normally innervated men were compared to assess the pattern of response to graded treadmill exercise. A 5-minute postexercise venous lactate sample was also obtained. Respiratory exchange ratio and ventilation (Ve) were higher in denervated patients than in normals during submaximal exercise. Peak values (normals vs denervated) for heart rate (172 vs 159 beats/min), blood pressure (189 vs 167 mm Hg), oxygen uptake (37 vs 25 ml/kg/min), oxygen pulse (0.22 vs 0.16 ml/kg/beat) and work time (26.2 vs 18.0 minutes) were higher in normals than in cardiac transplant recipients. Peak ventilatory equivalent (2.14 vs 3.13 l/ml/kg) and lactate values were higher for transplants than for normal subjects, but there were no significant intergroup differences in peak Ve or in the respiratory exchange ratio. In cardiac transplant recipients, work time correlated inversely with a measure of rejection history (r = -0.59, p less than 0.01). The response of cardiac transplant recipients to treadmill work differs from that of normal men and reflects a diminished ability to meet the oxygen demands of the exercising periphery.
The mural left anterior descending coronary artery, strenuous exercise and sudden death.
Authors: Morales A R , Romanelli R , Boucek R J
Published: June 2012

Postmortem studies of three ostensibly healthy persons whose unheralded death occurred incidental to strenuous exercise revealed an obstructed but mural left anterior descending (LAD) artery, diminished vascularity to the posterior left ventricle and ventricular septum, and morphologic evidence of patchy, ischemic necrosis of the ventricular septum in different stages of healing. Although mural coronary arteries are considered a normal anatomic variant, our observations, coupled with reported clinical studies, strongly suggest that systolic constriction of the LAD artery may precipitate death in selected subjects.
Dystrophic degeneration of papillary muscle and ventricular myocardium. A basis for mitral valve prolapse in Duchenne's muscular dystrophy.
Authors: Sanyal S K , Johnson W W , Dische M R , Pitner S E , Beard C
Published: June 2012

The hearts of three children who died with Duchenne's progressive muscular dystrophy and features of mitral valve prolapse were examined to find if the valve disorder arose from cardiomyopathy due to the primary disease or from dystrophic changes in th mitral valve itself. Gross, histologic and ultrastructural features of mitral valve annulus, anterior and posterior leaflets, chordae tendineae, right and left ventricles, and anterior and posterior papillary muscles were compared with those of similar tissues from normal children of matched age and sex. Fibrosis and myofibrillar lysis--most extensive in posterior papillary muscle and in the posterobasal segment of the left ventricle--were the main histopathologic findings. Myofibrillar lysis was characterized by a total loss of actin and myosin myofilaments. By contrast, the mitral valve annulus, its leaflets and the origin, distribution pattern, length and thickness of chordae tendineae were entirely normal. These observations establish that mitral valve prolapse syndrome in Duchenne's dystrophy is an expression of cardiomyopathy involving papillary muscle and ventricular myocardium rather than a result of dystrophic changes in the mitral valve leaflets, annulus or chordae tendineae.
Detection of dysrhythmia in pediatric patients with mitral valve prolapse.
Authors: Kavey R E , Sondheimer H M , Blackman M S
Published: June 2012

The association of dysrhythmias with mitral valve prolapse in pediatric patients was investigated by graded treadmill exercise testing and 24-hour ambulatory ECG monitoring. Twenty-six unselected patients with a clinical diagnosis of mitral valve prolapse confirmed by echocardiography or angiocardiography or both were studied. On 24-hour ambulatory ECG monitoring, six patients (23%) had potentially serious ventricular dysrhythmias. Five of these patients also manifested ventricular dysrhythmias on treadmill exercise testing. Neither standard ECG abnormalities nor clinical symptoms correlated with detected dysrhythmias. This study shows that potentially serious ventricular arrhythmias are common in pediatric patients with mitral valve prolapse and that ambulatory ECG monitoring and treadmill exercise testing are useful for detecting dysrhythmias.
Reciprocating tachycardia using bilateral anomalous pathways: electrophysiologic and clinical implications.
Authors: Cinca J , Valle V , Gutierrez L , Figueras J , Rius J
Published: June 2012

A patient who had disabling supraventricular tachycardia showed electrophysiologic evidence of coexistent right and left Kent bundles. The supraventricular tachycardia was accelerated by sequential antegrade and retrograde conduction over the right and left Kent bundles, respectively. Spontaneous blocking of the conduction through the right Kent bundle was associated with a slowing of the tachycardia and with the appearance of right bundle branch block (RBBB). Antegrade conduction was through the left bundle branch and was followed by an early retrograde atrial activation through the left Kent bundle, with consequent shortening of the ventriculoatrial (VA) interval. Thus, the coexistence of bilateral Kent bundles can be suspected whenever shortening of the VA interval in external electrocardiographic recordings occurs in the presence of a tachycardia with a RBBB pattern in a patient with right-sided preexcitation. Our data also showed that bilateral accessory pathways may have different electrophysiologic properties and that unequal response to antiarrhythmic drugs may be expected.
Ordering patterns and clinical impact of cardiovascular nuclear medicine procedures.
Authors: Goldman L , Feinstein A R , Batsford W P , Cohen L S , Gottschalk A , Zaret B L
Published: June 2012

We analyzed the ordering and impact of the first 171 fee-for-service cardiovascular nuclear medicine procedures at one hospital. The ordering physicians said 72% of the study results were useful and 28% contributed to changes in patient management. Experienced cardiology reviewers, however, felt that only 65% of studies were appropriately ordered, that 97% of appropriately ordered studies provided potentially useful information, and that 12% of all studies made important contributions to appropriate changes in patient management. The revieweres were most likely to rate exercise thallium procedures and procedures ordered by physicians from distant hospitals as being appropriately ordered and having important clinical impact. We conclude that (1) ordering physicians and revieweres may disagree substantially in their estimates of the impact of a diagnostic test; and (2) although a test may yield important information in appropriate patients, its total clinical impact will depend on how often it is suitably ordered and used.
Carotid sinus reflex in patients undergoing coronary angiography: relationship of degree and location of coronary artery disease to response to carotid sinus massage.
Authors: Brown K A , Maloney J D , Smith C H , Haritzler G O , Ilstrup D M
Published: June 2012

Heart rate and blood pressure responses during and after carotid sinus massage were examined in 66 patients just before coronary angiography. A significant relationship was found between heart rate and blood pressure responses and (1) angina pectoris class, (2) total coronary artery disease score and (3) presence of high-grade (> 90%) stenosis of any of the three major coronary arteries. Only patients with contraction abnormalities of the anterolateral left ventricular region had greater cardionhibitory responses than patients with normal left ventricular angiograms. Among patients with normal left ventricular angiograms, those with more than 50% stenosis of one or more vessels had significantly (p < 0.01) greater responses than those with no or minimal coronary artery disease. All 21 hypersensitive (asystole longer than 3 seconds) patients had significant multivessel coronary artery stenoses or single-vessel high-grade stenosis (greater than or equal to 90%) proximal to the atrioventricular nodal artery. None of the 11 patients with normal coronary arteries had an exaggerated response to carotid sinus massage. These data support the association of an exaggerated response to carotid sinus massage in the presence of symptomatic coronary artery disease and suggest that the magnitude of response is influenced by the severity of the disease.
Clinical course of patients with normal or slightly or moderately abnormal coronary arteriograms: 10-year follow-up of 521 patients.
Authors: Proudfit W L , Bruschke V G , Sones F M
Published: June 2012

The clinical course was followed for 10 years in 521 patients whose coronary arteriograms did not show any severe obstruction. Coronary disease had been suspected in all patients before arteriography. Two of 357 patients thought to have normal arteriograms died from coronary disease and two of 101 patients died who had less than 30% estimated narrowing of at least one coronary artery. Ten deaths ascribed to coronary disease occurred in 63 patinets who had 30-50% narrowing of at least one major coronary artery. The difference in death rates between the normal or mildly diseased groups and the group that had moderate narrowing was significant (p < 0.01). Coronary events (death from coronary disease, subsequent myocardial infarction, or arteriographic evidence of progression of coronary obstruction) occurred in 2.1% of those who had normal arteriograms, 13.8% of the group with mild lesions, and 33% of those with moderate degree of coronary arterial narrowing.
Outcome in medically treated coronary artery disease. Ischemic events: nonfatal infarction and death.
Authors: Harris P J , Lee K L , Harrell F E , Behar V S , Rosati R A
Published: June 2012

In this study we extended the characterization of outcome in 1214 medically treated patients with coronary disease by considering nonfatal infarction and death together as ischemic events. At 7 years, the cumulative event rate was 47% (18% for nonfatal infarction as the initial event and 29% for death as the initial event). In multivariable analysis of 81 baseline descriptors, 11 (six clinical and five catheterization) were independent predictors of events. Progressive chest pain, number of diseased vessels, left main stenosis and left ventricular (LV) function were the most important predictors. Progrressive pain was a more important predictor of total events than of survival alone. In patients with one-, two- or three-vessel disease and normal LV function, nonfatal infarcation accounted for at least 50% of initial events. In patients with left main disease or severe LV dysfunction, death was the predominant event. These results have important implications for interpreting the natural history of coronary artery disease.
Impaired early left ventricular relaxation in coronary artery disease: effects of intracornary nifedipine.
Authors: Rousseau M F , Veriter C , Detry J M , Brasseur L , Pouleur H
Published: June 2012

It has been shown that the maximal rate of left ventricular (LV) relaxation is impaired in patients with coronary artery disease (CAD) under basal conditions. To test the hypothesis that this impaired LV relaxation could be related to viable but metabolically abnormal myocardium, we studied the time course of isovolumic LV pressure fall in 21 patients with CAD and in 13 control subjects under basal conditions. This study was repeated after intracoronary injection of the calcium antagonist nifedipine (N) in 11 patients with CAD and in eight controls. Our data showed that isovolumic pressure fall was biexponential in 20 of 21 CAD patients and in six of 13 controls. Moreover, the time constant of isovolumic pressure fall during the first 40 msec after peak (negative) dP/dt (T1) was significantly greater in CAD patients than in controls (62 +/- 3 vs 44 +/- 1 msec, p < 0.002); the time constant of pressure fall during the 40-80 msec after peak (negative) dP/dt (T2) was similar in both groups ( 42 +/- 2 vs 39 +/- 2 msec, NS). Thirty seconds after injection of nifedipine, T1 and T2, were significantly prolonged in patients with CAD (14 msec and 16 msec, respectively, p < 0.005) and in controls 12 msec and 14 msec, respectively, p < 0.05), and a negative inotropic effect was observed in both groups (peak (positive) dP/dt - 16% in controls and -23% in CAD patients, p < 0.01). At rest, impairment of isovolumic relaxation in CAD patients is mainly limited to the first 40 msec after peak (negative) dP/dt, suggesting a dyssynchronous wall motion. This impairment of LV relaxation is better identified by T1 than by peak (negative) dP/dt in individual patients, and cannot be improved by administration of a calcium antagonist.
Body surface distributions of repolarization forces during acute myocardial infarction. I. Isopotential and isoarea mapping.
Authors: Mirvis D M
Published: June 2012

Although ST-segment abnormalities during acute myocardial infarction are clinically important, the total thoracic distribution of these repolarization potentials has not been reported. To provide this information, 24 patients with acute myocardial infarction were studied. Isopotential body surface maps were constructed from potentials sensed by 150 anterior and posterior electrodes. Patterns from 12 patients with anterior lesions demonstrated the appearance of repolarization potentials 21.3 +/- 4.6 msec before the end of the QRS complex. During the ST segment, potential distributions were characterized by a single anterior maximum that remained fixed in location but increased in intensity as repolarization progressed. Distributions in the remaining subjects with inferior lesions were analogously characterized by (1) the onset of repolarization 34.6 +/- 12.4 msec before termination of the QRS complex and (2) a single anterior minimum located on the left anterior superior thorax, with positive potentials distributed around the lower thoracic margins. These data suggest that electrocardiographic changes after acute myocardial infarction include (1) marked overlap between activation and recovery patterns and (2) isopotential surface patterns with relatively simple topographic configurations, such as expected of a single-dipole equivalent cardiac generator.
Noninvasive and invasive demonstration of spontaneous regression of coronary artery disease.
Authors: Roth D , Kostuk W J
Published: June 2012

Spontaneous regression of a left anterior descending coronary artery lesion was diagnosed by noninvasive testing (stress electrocardiography and thallium-201 myocardial imaging) and confirmed on selective coronary angiography in a 46-year-old man. The patient's clinical improvement, normalization of stress ECG and thallium-201 imaging, together with the loss of collateral filling, confirm that the regression is genuine. This case provides evidence that regression of coronary atherosclerosis can occur in man.
Prognosis in primary ventricular tachycardia in the pediatric patient.
Authors: Bergdahl D M , Stevenson J G , Kawabori I , Guntheroth W G
Published: June 2012

Five male pediatric patients with primary ventricular tachycardia are described. Although three were initially in congestive heart failure due to the tachycardia and were extremely difficult to manage, all have completely recovered, are not taking medication, and are free of arrhythmia. Three of the patients required long-term management with quinidine, with a therapeutic goal of controlling the heart rather than abolishing the arrhythmia. No growth disturbances were found in those three patients. A review of reported cases revealed 71 infants and children with ventricular tachycardia not associated with heart disease or systemic disorders; only four deaths were reported (5.6%). In the primary form of ventricular tachycardia in children, complete pharmacologic suppression may not be achieved without seriously endangering the normal electrophysiologic functions. Controlling the rate to an asymptomatic level with pharmacologic means is safer for a problem that may be self-limited.
Is postextrasystolic potentiation dependent on Starling's law? Biplane angiographic studies in normal subjects.
Authors: Sung C S , Mathur V S , Garcia E , de Castro C M , Hall R J
Published: June 2012

The cineangiograms of 26 normal subjects were analyzed to study the effect of Starling's mechanism on postextrasystolic potentiation. The end-diastolic volumes (single plane and biplane) of the left ventricle were similar in the regular sinus beat before an extrasystole and sequential sinus beats after an extrasystole. However, the ejection fraction, mean normalized systolic ejection rate, mean velocity of fiber shortening and long-axis shortening were consistently larger in the first sinus beat after an extrasystole. We conclude that postextrasystolic potentiation is independent of left ventricular end-diastolic volume in normal human hearts and the compensatory pause after an extrasystole does not result in increased end-diastolic volume.
The complementary roles of M-mode echocardiography and scintigraphy in the evaluation of adults with suspected left-to-right shunts. Additional observations on the role of two-dimensional echocardiography.
Authors: Botvinick E H , Schiller N B
Published: June 2012

We sought to determine the relative clinical abilities and roles of echocardiography and scintigraphy in left-to-right shunt diagnosis. M-mode echocardiographic and scintigraphic studies were analyzed in 37 adults presenting diagnostic difficulties with suspected left-to-right shunts. The historic, physical, radiographic and electrocardiographic data were frequently ambiguous. An enlarged right ventricle on M-mode echocardiography was a sensitive (100%) but not specific (55%) indicator of atrial septal defect (ASD). M-mode lacked sensitivity for ventricular septal defect (VSD) and patent ductus arteriosus (PDA). In a few studies, two-dimensional echocardiography provided additional specific and clinically important anatomic information. Scintigraphic analysis demonstrated complete diagnostic accuracy and excellent localizing and quantitative abilities in all patients studied. Because it is extremely sensitive to ASD, free of any exposure to radioactivity, entirely noninvasive and may be simply and visually analyzed, echocardiography is the study of choice in the preliminary evaluation of patients presenting diagnostic difficulty with suspected ASD. Scintigraphy is the study of choice in the preliminary evaluation of patients presenting diagnostic difficulty with suspected VSD and PDA and is the logical response to the finding of echocardiographic right ventricular enlargement when the diagnosis remains in doubt.
Enhancement of tactile perception in palpation.
Authors: Smith D , Craige E
Published: June 2012

We studied tactile perception in palpation of the precordium to determine the frequency response of the hand and to improve, if possible, the sensitivity of the hand as a transducer for precordial movement. The threshold of tactile sensation was determined for 10 subjects by manipulating the amplitude of movement of an impulse generator at each of a series of frequency settings in the subaudible range (1-40 Hz.) Relatively gross movements were necessary to achieve threshold in the lowest frequencies. A more than four-fold increase in sensitivity was obtained by restraining the fingers with the application of a light but unyielding disc to their dorsal surface. Clinical application of this device permitted the easy perception of a systolic thrust as well as a rapid filling wave in normal adult subjects over the right ventricle at the left sternal edge, an area generally considered to be motionless by conventional palpation.
Elevated plasma free drug concentrations of propranolol and diazepam during cardiac catheterization.
Authors: Wood A J , Robertson D , Robertson R M , Wilkinson G R , Wood M
Published: June 2012

Patients who undergo cardiac catheterization are frequently taking propranolol and are often premedicated with diazepam. Because the intensity of a drug's action is determined by free, or non-protein-bound, levels in plasma, changes in the degree of protein binding may profoundly alter the pharmacologic effect. We examined the effects of heparin on the free levels of propranolol and diazepam in six patients who underwent cardiac catheterization. After heparinization, the free fraction of diazepam increased more than fourfold, from 1.8 +/- 0.1% to 7.9 +/- 1.2% (p < 0.002) and the free levels increased from 2.0 +/- 0.5 to 8.4 +/- 2.2 ng/ml (p < 0.025); the free fraction of propranolol increased from 7.4 +/- 0.9% to 12.5 +/- 1.4% (p < 0.001). The increase in free drug concentration was associated with elevated free fatty acid levels, which rose from 181 +/- 7 micrograms/ml to 596 +/- 119 micrograms/ml (p < 0.02). Increases in the free levels of propranolol and diazepam produced by heparinization during cardiac catheterization may result in increased pharmacolaogic effect, such as excessive sedation or respiratory depression.
Recanalization of an acutely occluded aortocoronary bypass by intragraft fibrinolysis.
Authors: Rentrop P , Blanke H , Karsch K R , Kostering H , Oster H , Leitz H
Published: June 2012

Acute thrombotic occlusion of an aortocoronary bypass graft to the left anterior descending coronary artery (LAD) was successfully dissolved by selective infusion of streptokinase into the graft at 2000 U/min for 1 hour via catheter. There was partial recanalization of the graft and complete filling of the LAD within 15 minutes. After 1 hour of lysis, the graft was completely patent, although high-degree narrowing at the site of the proximal anastomosis was still present. Follow-up angiography 16 days later revealed persistent patency of the graft and disappearance of narrowing at the site of proximal anastomosis. The relatively low total dose of streptokinase (140,000 U) did not result in a systemic hyperlytic state. There were no complications. The technique may prove useful in acute graft occlusion but needs further evaluation.
The law on cardiovascular devices: the role of the Food and Drug Administration and physicians in its implementation.
Authors: Rahimtoola S H , Rahmoeller G A
Published: June 2012

The Medical Device Amendments of 1976 gave the Food and Drug Administration (FDA) new authority to regulate all medical devices. This regulation requires that manufacturers provide data supporting the safety and effectiveness of new and modified devices before marketing them, and eventually provide similar data even for devices now on the market. Those working in the cardiovascular field use a device every day of their professional lives; therefore, the Medical Device Amendments will have a significant effect on everyone in the field. We must understand the law so that we can provide scientific guidance to the FDA and to the medical device industry; in this article we aim to provide the necessary information.
The effect of mild-to-moderate mental stress on coronary hemodynamics in patients with coronary artery disease.
Authors: Bassan M M , Marcus H S , Ganz W
Published: June 2012

Eleven men with coronary artery disease were studied to determine whether they would manifest inappropriate coronary vasoconstriction in response to mental stress. Mental stress was induced by having the patient perform difficult mental arithmetic in time with a clicking metronome. Aortic blood pressure and thermodilution coronary sinus blood flow were recorded continuously before and during the mental arithmetic. For the group, heart rate rose from 70 to 82 beats/min, systolic blood pressure rose from 161 to 181 mm Hg and diastolic blood pressure rose from 71 to 78 mm Hg. Coronary resistance decreased by 16%. The index of myocardial oxygen consumption rose by 40%, and there was an equivalent rise in coronary sinus blood flow of 41%, with no changes in coronary arteriovenous oxygen difference. Because the increase in myocardial oxygen consumption was accompanied by a proportional increase in coronary sinus blood flow, a decrease in coronary resistance and no change in myocardial oxygen extraction, we conclude that the response of patients with coronary artery disease to at least moderately severe mental stress is not characterized by abnormal coronary vasoconstriction.
Effects of methylprednisolone on P50, 2,3 diphosphoglycerate and arteriovenous oxygen difference in acute myocardial infarction.
Authors: Kalter E S , Henning R J , Thijs L , Vincent J L , Becker H , Carlson R W , Weil M H
Published: June 2012

In a double-blind randomized study, 30 mg/kg of methylprednisolone sodium succinate (MPN) or 15 mg/kg of mannitol placebo (PL) were infused in 28 patients after acute myocardial infarction. Measurements were obtained immediately before and after for 24 hours after the initial infusion. The partial pressure of oxygen at 50% saturation of hemoglobin (P50) did not change significantly in vitro or in vivo after MPN, whereas 2,3 diphosphoglycerate (2,3 DPG) increased from 13.2 to 14.2 mumol/g Hb (p < 0.05) in the group receiving PL. The arteriovenous oxygen difference (Ca-VO2) remained constant after MPN or PL. The cardiac index (CI) increased after MPN (p < 0.02) associated with an increase in the oxygen consumption index (CI X A-V O2) from 146 to 170 ml/min/m2 (p < 0.05). These data show that MPN increases CI after acute myocardial infarction, but has no specific effects on P50, 2,3 DPG or Ca-VO2.
Viral illness and the postpericardiotomy syndrome. A prospective study in children.
Authors: Engle M A , Zabriskie J B , Senterfit L B , Gay W A , O'Loughlin J E , Ehlers K H
Published: June 2012

Postoperative fever and pericardial-pleural reaction, designated postpericardiotomy syndrome (PPS), is a common complication of cardiac surgery involving entry into the pericardium. To determine whether the etiology of PPS is viral or immunologic, we undertook a prospective, triple-blind study of consecutive long-term survivors of intrapericardial surgery in the pediatric age group. We evaluated clinical evidence of syndrome and concurrent appearance of antiheart antibody (AHA) by indirect immunofluorescence and antiviral antibody (AVA) by complement fixation in sera preoperatively and serially postoperatively. Incidence of PPS was 27% overall in 400 subjects, but only 3.5% in infants younger than 2 years of age. AHA in high titer appeared in all patients with PPS. A fourfold or greater rise in titer to AVA was found in 70% of these but in only 5% of those with negative AHA and no PPS. AVA rise, tested in 280 consecutive patients, was to no single one of the eight viruses studied (adenovirus, cytomegalovirus, and coxsackievirus B 1-6). Instead, the rise and fall, consistent with antiviral response to a recent infection, was exhibited usually to one but occasionally to two or more viruses, and the viral prevalence changed from year to year, as did that in the community. The study suggests that concurrent fresh or reactivated viral illness plays a role in triggering the immunologic response that characterizes the PPS.
Quantitative difference in "critical" stenosis between right and left coronary artery in man.
Authors: Rafflenbeul W , Urthaler F , Lichtlen P , James T N
Published: June 2012

Coronary artery stenoses that limit blood flow below demand are considered critical. In this comparative study we investigated whether the same degree of stenosis in either the proximal third of the right coronary artery (RCA) or the proximal third of the left anterior descending artery (LAD) causes critical flow reduction. Lesions were quantified from 35-mm cinefilms in multiple projections using a vernier caliper. These morphometric measurements were correlated with various manifestations of critical flow reduction, such as angina pectoris, development of collateral vessels and segmental wall motion abnormalities. In 13 patients with anginal pain and isolated RCA stenosis, the mean degree of obstruction was 63% area stenosis, which was significantly lower (p < 0.05) than that measured in 17 symptomatic patients who had isolated obstructions of the LAD (77% area stenosis). In patients with an identical degree of obstruction (78%) in either the LAD or RCA, collateral vessels were angiographically demonstrable in 53% of the RCA stenoses but in only 29% of the LAD stenoses. Furthermore, when the stenoses were less than 63% in the RCA and LAD, regional wall motion abnormalities were more frequently (p < 0.05) associated with RCA than with LAD stenoses. These observations indicate that a significantly smaller percent area of stenosis is critical in the RCA than in the LAD.
The effects of intravenous nitroglycerin on hemodynamics, coronary blood flow and morphologically and enzymatically estimated infarct size in conscious dogs.
Authors: Fukuyama T , Schechtman K B , Roberts R
Published: June 2012

Nitroglycerin (TNG) decreases ST-segment elevation accompanying myocardial ischemia, but its effect on morphometrically and enzymatically estimated infarct size (IS) has not been defined. Accordingly, coronary occlusion was produced in 92 conscious dogs; 65 survived for 24 hours. Thirty-three received TNG (200-300 microgram/min i.v. for 8 hours) and the results were compared with those in 32 untreated dogs. Coronary blood flow (CBF) was measured with tracer microspheres (141Ce, 85Sr and 95Nb) 5 minutes after occlusion before TNG, 20 minutes after TNG and again at 8 hours. Mean blood pressure decreased from 103 to 84 mm Hg with TNG, vs 99 to 94 mm Hg in controls (p > 0.02). Nitroglycerin increased CBF in the subendocardium of ischemic areas by 45% (0.09 to 0.13 ml/min/g). The dogs were sacrificed after 24 hours and IS was estimated morphometrically (25 +/- 1% vs 27 +/- 1% of left ventricular weight) and from myocardial CK depletion (23 +/- 1% vs 24 +/- 1%) were similar for the two groups. Thus, despite increased subendocardial CBF, prolonged i.v. TNG did not decrease infarct size, although a 15% difference would have been detected with this sample size. TNG may relieve coronary spasm but does not appear to be beneficial with sustained coronary occlusion.
Estimation of myocardial involvement in patients with acute myocardial infarction by two-dimensional echocardiography.
Authors: Nixon J V , Narahara K A , Smitherman T C
Published: June 2012

To determine whether real-time two-dimensional echocardiography (2-D echo) can estimate the extent of myocardial involvement in patients with acute myocardial infarction (MI), regional wall motion on serial short-axis 2-D echo recordings was analyzed and the summed scores were compared with estimates of infarct involvement by thallium-201 reperfusion (Tl) and technetium-99m stannous pyrophosphate (99mTc-PYP) scintigraphy. Thirty-two consecutive male patients admitted with their first MI were studied; 10 patients had anterior, 16 had inferior and six had subendocardial MIs. Two patients were technically unsuitable for 2-D echo studies. Twenty patients had Tl scintigrams and 29 had 99MTc-PYP scintigrams. Summed 2-D echo scores correlated closely with estimates of infarct involvement by Tl (r = 0.87) and with estimates of infarct size by 99mTc-PYP (r = 0.74). The location of MI by 2-D echo agreed with the electrocardiographic location in 26 of 29 patients; discrepancies occurred in one inferior and two subendocardial MIs. Predischarge 2-D echo failed to identify extension of transmural infarction. However, two patients whose subendocardial MIs progressed to transmural MIs were identified. This study shows that 2-D echo is a valid method for the early estimation of the extent of myocardial involvement in patients with acute MI, especially transmural MIs. In particular, 2-D echo correlates closely with Tl reperfusion scintigraphy because both detect areas of ischemia and infarction.
Left stellectomy in the prevention of ventricular fibrillation caused by acute myocardial ischemia in conscious dogs with anterior myocardial infarction.
Authors: Schwartz P J , Stone H L
Published: June 2012

The potential of left stellectomy in reducing the incidence of ventricular fibrillation associated with acute myocardial ischemia was investigated in a new animal model for sudden death. Thirty-two dogs had an anterior myocardial infarction produced by ligation of the left descending coronary artery. One week later they were randomly allocated to a control or to an experimental group that underwent left stellectomy. One month after ligation while the dogs were conscious, a balloon occluder previously positioned around the circumflex coronary artery was inflated and the ensuing coronary occlusion was maintained for 10 minutes. Ventricular fibrillation occurred in 11 of 17 (65%) control dogs, compared with five of 15 (33%) (p < 0.05) in the experimental group. Among the survivors the incidence of arrhythmias was less in the experimental group compared with the control group. Infarct size (21 +/- 2% vs 20 +/- 2%), resting heart rate (143 beats/min vs 127 beats/min) and QTc (347 +/- 11 msec vs 349 +/- 13 msec) were similar between control and experimental groups. The dogs that died had a greater increase in heart rate at 1 minute postocclusion than survivors and also had significantly longer QT intervals. Our study indicates that left stellectomy exerts a major protective effect in reducing the incidence of ventricular fibrillation when conscious dogs with a previous anterior myocardial infarction undergo acute myocardial ischemia. This simple and safe surgical procedure may be considered for a clinical trial in subgroups of patients with ischemic heart disease at very high risk for sudden death.
Serial electrophysiologic testing of multiple drugs in patients with atrioventricular nodal reentrant paroxysmal tachycardia.
Authors: Bauernfeind R A , Wyndham C R , Dhingra R C , Swiryn S P , Palileo E , Strasberg B , Rosen K M
Published: June 2012

Serial electrophysiologic testing of multiple drugs was performed in 21 patients with recurrent atrioventricular (AV) nodal reentrant paroxysmal supraventricular tachycardia (PSVT). All patients had reproducible sustained PSVT induced before drug administration. Serial daily PSVT induction was attempted after administration of i.v. ouabain (0.01 mg/kg) (16 patients), i.v. propranolol (0.1 mg/kg (17 patients), i.v. ouabain + propranolol (same dosages) (12 patients), i.v. procainamide (600-1000 mg) (17 patients) and oral quinidine (1600-2400 mg/day) (nine patients). In two of 21 patients (10%), no tested drug prevented induction of sustained PSVT. In 19 of 21 patients (90%), one or more drugs prevented induction of sustained PSVT: ouabain--seven patients, propranolol--seven patients, ouabain + propranolol--seven patients, procainamide--11 patients, quinidine--seven patients. The site of action of ouabain and/or propranolol was either the antegrade limb or the retrograde limb (RL) of the circus movement. The site of action of procainamide or quinidine was always the RL. These 19 patients were treated with oral drugs, based on results of serial testing. Eighteen patients were successfully followed for 6-50 months. In 13 of these 18 patients PSVT did not recur. Two patients (11%) had > 95% reduction in frequency of PSVT recurrences, and three (17%) did not respond to chosen oral drugs. Serial electrophysiologic testing of multiple drugs is feasible in patients with AV nodal reentrant paroxysmal tachycardia. Drug responses are variable. In most but not all patients, serial electrophysiologic testing defines effective prophylactic drug therapy. This method of defining prophylactic drug therapy appears most suitable for patients with poorly tolerated tachycardias that occur only sporadically.
Effects of isoproterenol on abnormal intraventricular conduction.
Authors: Halpern M S , Chiale P A , Nau G J , Przybylski J , Lázzari J O , Elizari M V , Rosenbaum M B
Published: June 2012

An isoproterenol infusion (1.0-4.0 microgram/min) was administered to 15 patients with intermittent bundle branch block (BBB) and two patients with apparently fixed BBB. Three main effects were documented: (1) In all patients with phase 3, or tachycardia-dependent, BBB, isoproterenol caused a pronounced shortening of refractoriness in the affected fascicle. (2) In patients showing phase 4, or bradycardia-dependent, BBB, isoproterenol prolonged the phase 4 block range, probably because of enhanced diastolic depolarization. In one patient (four studies) in whom phase 4 block was not present, isoproterenol caused the appearance of a phase 4 block range. (3) In the two patients with fixed BBB, isoproterenol restored conduction, probably as a result of a hyperpolarizing effect. This study shows that isoproterenol tends to restore or improve conduction related to tachycardia-dependent block, but may impair conduction related to bradycardia-dependent block.
Successful surgical excision of focal paroxysmal atrial tachycardia. Observations in vivo and in vitro.
Authors: Wyndham C R , Arnsdorf M F , Levitsky S , Smith T C , Dhingra R C , Denes P , Rosen K M
Published: June 2012

A 41-year-old man had chronic, recurrent, drug-resistant paroxysmal right atrial tachycardia. Electrophysiologic studies revealed features suggesting atrial reentrance, including induction and termination of tachycardia with rapid atrial pacing and atrial extrastimuli. Endocardial catheter mapping localized the origin of tachycardia to the right atrial appendage. Intraoperative epicardial mapping refined the localization to the posterolateral rim of the appendage. The appendage was excised and the tachycardia was permanently cured. Microelectrode studies on the excised tissue revealed an inducible rhythm localized to a small area of the atrial endocardium, characterized by rapid pacing induction, rhythmicity generated from a suprathreshold afterdepolarization, low maximum diastolic potential, low overshoot potential and a smooth transition from phase 4 to phase 0, suggesting triggered automaticity. This is the first observation in man of probable triggerable atrial automaticity, which may be a direct counterpart of the clinical arrhythmia. The successful surgical outcome indicates that a focal atrial tachycardia can be excised in selected patients.
Right Auricular and Ventricular Pressure Patterns in Constrictive Pericarditis
Authors: YU PAUL N. G. , LOVEJOY FRANK W. , JOOS HOWARD A. , NYE ROBERT E. , MAHONEY EARL B.
Published: June 2012

The characteristic intracardiac pressure patterns of four patients with constrictive pericarditis are described. The significance of a high ratio between right ventricular end-diastolic and systolic pressure is demonstrated. Postoperative changes are described in one patient and the mechanism of the production of the pressure patterns is discussed.
The Selection and Medical Management of Patients with Mitral Stenosis Treated by Mitral Commissurotomy
Authors: GRIFFITH GEORGE C. , MILLER HAROLD , COSBY RICHARD S. , LEVINSON DAVID C. , DIMITROFF SIM P. , ZINN WILLARD J. , OBLATH ROBERT W. , HERMAN LAWRENCE M. , JOHNS VARNER J. , MEYER B. W. , JONES JOHN C.
Published: June 2012

The selection of patients for mitral commissurotomy must be made after considering all manifestations of the rheumatic state. A conservative approach is urged and no patients should be operated upon without evidences of increasing pulmonary hypertension and right heart strain. The preparation of the patient, the management of the arrhythmias during surgery and the postoperative care are the full responsibilities of the physician. A team composed of physiologists, cardiologists and surgeons must work together.
Reaffirmation of the Auriculoventricular Conduction System in Man
Authors: READ JOHN L. , HEGRE ERLING S. , RUSSI SIMON
Published: June 2012

Gross and microscopic studies of the auriculoventricular conduction system were performed in 60 human hearts. A unique technic is introduced which will produce a photographic record of undistorted serial sections through a block containing the auriculoventricular node, auriculoventricular bundle and branches. By projecting the completed film as a motion picture, the course and changing relationships of component structures can be followed from level to level in uninterrupted sequence. The neurogenic versus the myogenic concept of cardiac conduction is reviewed at length.