bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship of Surface Electrogram Recordings to Activity in the Underlying Specialized Conducting Tissue
Authors: MYERBURG ROBERT J. , NILSSON KRISTINA , ZOBLE ROBERT G.
Published: June 2012

Surface electrodes are widely used to study the electrophysiology of the A-V conducting system. The recording of activity from the human in-situ His bundle represents a practical, clinically useful adaptation of surface recording technics. The interpretation of data accumulated by this means must be considered in relation to the extent to which the surface recordings from the specialized conducting system accurately reflect activity in the underlying tissue. A combination of microelectrode technics to record transmembrane action potentials and surface recording technics on isolated preparations of canine conducting tissue were used to approach this question. Under many conditions the surface electrogram was found to be an accurate indicator of the presence and timing of impulses in the conducting system. However, during early premature activity, marked decreases or complete absence of surface electrogram voltage could occur at coupling intervals at which premature impulses were still able to propagate through tissue under the electrodes. In addition, early premature activity could be associated with reversal of polarity of the surface electrogram without reversal of the direction of propagation. Inaccurate relationships between the time of inscription of the surface recording and the time of passage of the propagating wavefront beneath the surface electrodes also occurred with early premature impulses. Finally, there is some evidence that surface electrograms primarily reflect that activity in the most superficial levels of tissue.
Long-Term Prognosis of Rheumatic Fever Patients Receiving Regular Intramuscular Benzathine Penicillin
Authors: TOMPKINS DOROTHY G. , BOXERBAUM BERNARD , LIEBMAN JEROME
Published: June 2012

The prognosis for 115 rheumatic fever patients subsequently receiving regular intramuscular penicillin prophylaxis for at least 5 years was studied. Average follow-up was 9.3 years, and 57 patients were followed for 10 years or longer. Of the 79 patients with acute mitral regurgitation, 70% lost their murmur from 4 days to 8.5 years after it was first heard. This is in contrast to those with acute aortic regurgitation which persisted in 73%. No patient developed mitral or aortic stenosis: this suggests that regular prophylaxis may prevent the development of stenosis. Congestive failure, cardiomegaly, and arrhythmia correlated closely with persistence of murmurs, but increased P-R interval, acute QRS or T-voltage variation or both, and ST-T abnormalities did not.
On the Mechanism of the Austin Flint Murmur
Authors: FORTUIN NICHOLAS J. , CRAIGE ERNEST
Published: June 2012

We studied mitral valve motion in 15 patients with aortic regurgitation and an Austin Flint murmur by recording simultaneously the phonocardiogram, apexcardiogram, and mitral valve echocardiogram. In 14 patients the murmur was presystolic, and in 13 of these a middiastolic component was present as well. The middiastolic component occurred after the period of rapid ventricular filling as the mitral valve was closing. The presystolic component occurred either as the mitral valve was rapidly closing following normal atrial opening movement or during the entire period of atrial systole. In this latter situation the valve did not open completely with atrial systole. All of these patients demonstrated a prominent A wave on the apexcardiogram. In patients with a two-component Flint murmur, isometric handgrip exercise greatly accentuated the murmur, altered the pattern of valve motion so that atrial systole was no longer effective in opening the valve, and reduced the size of the apex A wave.

One patient had only a middiastolic Flint murmur. The mitral valve was open for only a brief period in middiastole and did not reopen with atrial systole. Cardiac catheterization documented elevation of ventricular diastolic pressures above left atrial pressures during most of diastole. Amyl nitrite reduced diastolic ventricular pressure and permitted the mitral valve to open with atrial systole. The apex A wave, which was small at rest, increased in size after amyl nitrite.

Our findings suggest that the Flint murmur is due to antegrade flow across the mitral valve. The rumble occurs during rapid closure of the valve as flow velocity is increasing although actual volume of flow may be decreasing.
Combined Therapy with Vasodilator Drugs and Beta-Adrenergic Blockade in Hypertension
Authors: GOTTLIEB THOMAS B. , KATZ FRED H. , CHIDSEY CHARLES A.
Published: June 2012

The hypotensive efficacies of two vasodilators, hydralazine and minoxidil, were assessed as these drugs were used individually in combination with beta-adrenergic blockade and diuretics in 11 hypertensive patients in whom elevated blood pressure had not been adequately controlled previously by other antihypertensive therapy.

Control supine blood pressure fell from 191/128 mm Hg on propranolol and hydrochlorothiazide to 169/108 mm Hg on hydralazine, with a significantly greater reduction to 142/92 mm Hg on minoxidil. Although sodium retention and tachycardia were controlled by the use of concomitant diuretics and beta-blockade, an increment in each of these drugs was occasionally required to prevent these complications. Renal function was changed little with the decrease in blood pressure. Plasma renin increased from a standing control of 14.5 mµg/ml/hr to 35.9 and 31.1 mµg/ml/hr, respectively, on hydralazine and minoxidil. These data suggest the role of vasodilators used in combination with beta-blockers and diuretics and indicate the greater therapeutic efficacy of minoxidil.
Measurement of Left Ventricular Wall Thickness and Mass by Echocardiography
Authors: TROY BART L. , POMBO JOAQUIN , RACKLEY CHARLES E.
Published: June 2012

Echocardiographic measurements of minor axis and wall thickness and calculations from these two measurements of left ventricular end-diastolic volume and mass were performed in 24 patients and compared with angiocardiographic measurements of the same variables in corresponding patients. The echo-measured left ventricular end-diastolic chamber dimension (D
d
) correlated closely with the angiographic minor axis in the AP plane (correlation coefficient 0.87 and
se
± 0.45 cm) and with the minor axis from the lateral film (r = 0.91,
se
±0.39 cm). Similar correlations were found between measurements by these methods of wall thickness (r = 0.89,
se
±1.3 mm), of end-diastolic volume (r = 0.94,
se
±30.6 cc), and of left ventricular mass (r = 0.88,
se
±49.19 g). The reproducibility of this method was established by independent recordings and measurements of echo Polaroid films by two observers. The percent systolic wall thickening, as determined by echocardiography, identified subjects with ejection fractions greater or less than 0.50. Echocardiography offers a reliable and reproducible method for measuring left ventricular wall thickness and mass. Finally, ultrasound may provide an accurate method for measuring systolic wall thickening in man.
Acquired Right Bundle-Branch Block and Left Anterior Hemiblock in Ostium Primum Atrial Septal Defect
Authors: ECKBERG DWAIN L. , ROSS JOHN , MORGAN JACOB R.
Published: June 2012

Over a 3-year period of observation, the electrocardiogram in an adult patient with an ostium primum atrial septal defect changed from first-degree atrioventricular block alone to right bundle-branch block and left-axis deviation (left anterior hemiblock) with variable atrioventricular block. Coronary atherosclerosis was excluded by selective coronary arteriography. Although right bundle-branch block and left anterior hemiblock are commonly present at birth in patients with endocardial cushion defect, this is believed to represent the first reported instance in which these electrocardiographic abnormalities have developed under observation in later life. It is postulated that chronic hemodynamic stress contributed to the progression of disease in the conduction system.
Evaluation of Bretylium Tosylate for the Treatment of Premature Ventricular Contractions
Authors: ROMHILT DONALD W. , BLOOMFIELD SAUL S. , LIPICKY RAYMOND J. , WELCH RICHARD M. , FOWLER NOBLE O.
Published: June 2012

In a controlled setting bretylium tosylate was evaluated for efficacy, toxicity, onset, and duration of action in eight patients with frequent premature ventricular contractions (PVC). Four patients received a single im dose of bretylium, 4 mg/kg, with before and after control days; the other four patients received bretylium, 2 and 4 mg/kg, on different days with before and between control days. PVC were quantified from stored continuous ECG tape recordings by an automated arrhythmia-detection system. Five patients had 50% or more reduction of PVC frequency with bretylium 4 mg/kg, and one with 2 mg/kg. Bretylium 4 mg/kg but not 2 mg/kg reduced mean PVC frequency by half beginning at the sixth hour and continuing for 12 hours. Hypotension began within 1 hour. Maximum fall in mean supine blood pressure was 17/6 mm Hg with 2 mg/kg, and 25/12 mm Hg with 4 mg/kg. Plasma bretylium concentration was maximum at about 1 hour with a mean elimination half-life of 10 hours. A controlled quantitative method for evaluation of antiarrhythmic drugs in man demonstrated that bretylium can be effective in suppressing PVC frequency. The dissociation between hypotensive and antiarrhythmic effects of bretylium suggested that its antiarrhythmic effect was independent of adrenergic neuronal blockade.
Further Applications of Scintillation Scanning Technics to the Diagnosis and Management of Infants and Children with Congenital Heart Disease
Authors: HAGAN ARTHUR D. , FRIEDMAN WILLIAM F. , ASHBURN WILLIAM L. , ALAZRAKI NAOMI
Published: June 2012

Radionuclide angiography provides a reliable and extremely rapid technic for assessing the physiologic and pathologic features of cardiovascular malformations. Eighty-six infants and children and seven adults have been studied after intravenous infusion of
99m
technetium with a scintillation camera coupled to a computer-tape storage system. Pulmonary vascular isotope-dilution curves detected the presence or absence of left-to-right intra- or extracardiac shunts with great sensitivity. Therefore, the method has especially widespread applicability in the distinction between organic and innocent heart murmurs, in the evaluation of postoperative patients, and in the assessment of the natural course of selected, specific malformations. Moreover, also without resorting to cardiac catheterization, scintillation scanning is capable of defining great artery orientation and position, cardiac chamber position, approximate chamber volumes, and the distribution of pulmonary arterial blood flow. The method described is technically simple, without known risk, is easily applicable to large numbers of patients, and provides clinically important information concerning many forms of congenital heart disease.
Present Status of Digitalis Treatment of Acute Myocardial Infarction
Authors: KARLINER JOEL S. , BRAUNWALD EUGENE
Published: June 2012

The available experimental and clinical data still leave many unanswered questions concerning the role of digitalis therapy after acute myocardial infarction. It seems clear that little is to be gained by glycoside administration to patients with uncomplicated infarctions who do not have cardiomegaly. The precise role of digitalis therapy in the treatment of cardiogenic shock remains undefined on the basis of the available data. However, until evidence to the contrary appears, its use should be continued on the basis of experience with experimental cardiogenic shock and the presumption that this state, when observed clinically, is a form of extreme left ventricular failure.

Digitalis appears to be indicated in the treatment of atrial fibrillation with rapid ventricular rate complicating acute myocardial infarction. Other supraventricular arrhythmias, such as atrial flutter and ectopic atrial tachycardia, frequently require larger doses of the glycoside, and other means of therapy, such as antiarrhythmic agents or electrical conversion, may be preferable in such instances.

Digitalis is commonly utilized early in the treatment of congestive heart failure and cardiomegaly complicating acute myocardial infarction, despite the paucity of experimental and clinical evidence in support of such therapy. Whether the digitalis glycosides should continue to be used routinely in such patients is an important subject for clinical investigation.
Day-to-Day Variation of the Normal Orthogonal Electrocardiogram and Vectorcardiogram
Authors: WILLEMS JOS L. , POBLETE PIO F. , PIPBERGER HUBERT V.
Published: June 2012

Day-to-day variation of the corrected orthogonal electrocardiogram was investigated in 20 normal subjects. Ten recordings were made in each individual with chest electrode positions left unmarked first, after which 10 subjects underwent another series of 10 consecutive daily recordings with marked electrode locations. Mean and maximal day-to-day variations of durations and amplitudes of different deflections of scalar leads as well as variations of directions and magnitudes of several QRS and T spatial vectors have been studied using computer technics for measurement and analysis.

Repeat variability in the unmarked recordings was relatively large. For example, the maximum (96%) variability in QRS spatial maximum and in R-wave amplitudes in leads X and Z were, respectively, 0.50, 0.61, and 0.35 mv. Marking of the chest did reduce variability of amplitude and angular measurements by approximately 25%, but even then a substantial variation from day-to-day remained. Relative changes in T-wave amplitude and direction were greater than those of the QRS complex.

The results presented can be used as standards to assess ECG changes observed in serial electrocardiography.
Quantitative Angiocardiography in Ischemic Heart Disease
Authors: HAMILTON GLEN W. , MURRAY JOHN A. , KENNEDY J. WARD
Published: June 2012

Appropriate surgical and medical management of the patient with ischemic heart disease depends upon a thorough assessment of the clinical and pathophysiologic derangements in left ventricular function. This study examined the spectrum of abnormalities in ventricular function found in 66 patients with documented coronary artery lesions.

Catheterization and biplane angiocardiography were used to measure end-diastolic and end-systolic volume (EDV, ESV), systolic ejection fraction (SEF), ventricular mass (LVM), end-diastolic pressure (LVEDP), peak systolic and end-diastolic stress (PSS, EDS), and stroke work (SW). The pattern of ventricular contraction was assessed for hypokinesis, akinesis, and dyskinesis and graded according to severity.

The SEF, SW, and contractile pattern were sensitive and interrelated indicators of left ventricular contractile dysfunction or fiber shortening. Measurements of ventricular filling or fiber lengthening (EDV, LVEDP, EDS) were related but less sensitive parameters of dysfunction. However, when contractile function was reduced to about one half of normal, there was an associated marked increase in EDV, EDS, and LVEDP.

A wide spectrum of derangements was found ranging from virtually normal function in 18 patients with angina alone to severe dysfunction in 18 patients with myocardial infarction, mitral regurgitation, or heart failure.

Abnormalities in ventricular function were uniformly associated with myocardial infarction. Angina alone was associated with minimal or no ventricular dysfunction. Most patients with mitral regurgitation and all patients with heart failure had severe ventricular dysfunction manifested by an increase in EDV, LVM, and PSS, a marked decrease in SEF and SW, and a severe abnormality in contractile pattern.
Left Ventricular Dilatation and Diastolic Compliance Changes during Chronic Volume Overloading
Authors: MCCULLAGH WILLIAM H. , COVELL JAMES W. , ROSS JOHN
Published: June 2012

The magnitude and time course of alterations in left ventricular size, end-diastolic pressure (LVEDP), and stiffness consequent to chronic volume overloading were examined in conscious dogs. A large infrarenal aortocaval shunt was produced surgically, left ventricular dimensions were measured by cineradiography using radiopaque beads implanted subendocardially, and LVEDP was measured via an indwelling catheter. In nine experimental and seven control animals, LVEDP was related to the left ventricular end-diastolic diameter (LVEDD) over a range of LVEDP produced by transfusion and bleeding. In control studies LVEDP averaged 6.7 ± 1.42 (
sem
) mm Hg, LVEDD determined at 15 mm Hg LVEDP averaged 4.8 ± 1.13 cm, and the mean slope of linear stiffness curves was 45.9 ± 2.3 mm Hg/cm. Time-dependent changes in all of these parameters were observed following creation of the shunt: A progressive increase of LVEDP reached a maximum by 2 to 3 weeks, and when early postshunt studies (mean 5.2 days) were compared with late postshunt studies (mean 6.8 weeks) LVEDP had increased from 9.7 ± 1.2 to 18.9 ± 1.1 mm Hg (
P
< 0.01). There was a progressive, more gradual, increase in left ventricular size, LVEDD being 4.81 ± 2.4 cm in early postshunt and 5.34 ± 2.8 cm in late postshunt studies (
P
< 0.01). Left ventricular diastolic stiffness showed an increase from 50.2 ± 5.6 to 96.6 ± 10.7 mm Hg/cm between early and late postshunt studies, respectively (
P
< 0.01), and functional compliance was reduced. In six animals the shunts were closed; at approximately 1 week there was a substantial drop in LVEDP (9.5 ± 1.9 mm Hg), and although LVEDD were unchanged stiffness decreased to 58.6 ± 12.2 mm Hg/cm (
P
< 0.01). Observations up to 4 months after shunt closure suggested further progressive return toward normal of these parameters. It is concluded that chronic volume overloading in the normal dog causes a time-dependent shift to the right of the diastolic left ventricular pressure-dimension relation accompanied by a progressive reduction of diastolic compliance, and that these changes are at least in part reversible following correction of the shunt.
Wolff-Parkinson-White Syndrome
Authors: COUMEL PHILIPPE , WAYNBERGER MARC , FABIATO ALEXANDRE , SLAMA ROBERT , AIGUEPERSE JACQUES , BOUVRAIN YVES
Published: June 2012

Total atrioventricular bypass (Kent bundle) does not explain all the findings in some cases of Wolff-Parkinson-White (W-P-W) syndrome. Two cases are reported in which two accessory pathways, set in series or in parallel, could be demonstrated. In case 1, a short P-R interval, gap phenomenon, and presence of delta wave with either a short or long P-R interval suggested the hypothesis of an atrio-His accessory path (James fibers). The presence of a type-B delta wave during His stimulation demonstrated the takeoff of another bypass (Mahaim fibers) below or at the point of stimulation. The His-ventricle accessory path had a supernormal phase of conduction during either atrial or His stimulation. In case 2, the rapid spread of the impulse to the His bundle (P-H 65 msec) was responsible for a normal H-R interval (35 msec) during either reciprocating tachycardia or normal sinus rhythm wtih a nonwidened QRS and minimal W-P-W deformity (partial cancellation of the delta wave). During reciprocating tachycardia, alternatively short and long P'-H intervals with constant H-R (His bundle) and R-P' (Kent bundle) were due to alternate antegrade atrio-His conduction through the atrionodal nodal bypass (James fibers) and the A-V node. Surgical findings confirmed the existence of a left bundle of Kent. The division of the His bundle resulted in a maximal W-P-W deformity (type A) and abolished the reciprocating tachycardia.
Congenital Cardiovascular Disease and Anomalies of the Third and Fourth Pharyngeal Pouch
Authors: FREEDOM ROBERT M. , ROSEN FRED S. , NADAS ALEXANDER S.
Published: June 2012

Patients with the third and fourth pharyngeal pouch syndrome, thymic and parathyroid aplasia or hypoplasia, have a very high incidence of aortic arch anomalies and congenital heart disease. These patients present with a unique syndrome characterized by profound hypocalcemia, defective thymic-mediated cellular immune function, and cardiovascular anomalies. The cardiac abnormalities most frequently are conotruncal malformations of the tetralogy of Fallot or truncus arteriosus types and are often the cause of death. Patients with profound neonatal hypocalcemia should be screened for evidence of normal thymic function and congenital heart disease.
D-Bulboventricular Loop with L-Transposition in Situs Inversus
Authors: ANDERSON R. H. , ARNOLD R. , JONES R. S.
Published: June 2012

In the case described anatomically corrected transposition of the great vessels is associated with situs inversus. Anatomically corrected transposition is extremely rare, and has not been previously reported with situs inversus. This type of transposition should not be confused with classical corrected transposition. Thus the case examined exhibited a D-bulboventricular loop with L-transposition and atrial inversion, so that blood flow was physiologically incorrect as in classical complete transposition. In the case examined, it was also found that bulbar musculature was present between the aorta and the mitral valve.

Additional study of the conducting tissue revealed inversion of the sinoatrial node with the atria, and also of the atrial portion of the atrioventricular node. The atrioventricular bundle and its branches were in expected positions in relation to a large ventricular septal defect. These results are discussed with regard to previous reports and to the embryology of the conducting tissue.
Contribution of Quantitative Assay Technics to the Understanding of the Clinical Pharmacology of Digitalis
Authors: SMITH THOMAS W.
Published: June 2012

Despite recent advances in understanding of the pharmacokinetics and electrophysiologic effects of cardiac glycosides, digitalis toxicity remains distressingly common in clinical practice. Another substantial group of patients is markedly underdigitalized, failing to gain the full therapeutic benefits of optimal use of these drugs. Since cardiac digitalis toxicity is a dose-related phenomenon, and serum or plasma digoxin and digitoxin concentrations rise with increasing doses, at least a statistical correlation between circulating levels and clinical state might be expected. Increasing availability of serum or plasma digitalis concentration measurements thus offers the clinician a potential means of improving the patient's chances of benefiting from treatment with cardiac glycosides. Assay methods in current use include a double-isotope dilution derivative method (digitoxin), red cell
86
Rb-uptake inhibition (digitoxin and digoxin), Na
+
-K
+
ATPase inhibition (digitoxin), ATPase enzymatic displacement (digitoxin and digoxin), gas chromatography (digoxin), and radioimmunoassay (digitoxin, digoxin, and ouabain).

The rapidly expanding literature reporting clinical experience with these technics reflects general agreement that mean serum or plasma digoxini and digitoxin levels are significantly higher in patients with clinical evidence of toxicity compared with nontoxic patients. Nevertheless, multiple factors influence individual responses, and blood level data must be interpreted in the overall clinical context. Hypokalemia, hypercalcemia, hypomagnesemia, acid-base disturbances, hypoxemia, and hypothyroidism all tend to decrease tolerance to any given digitalis dose or blood level. Autonomic nervous system tone and other drugs concurrently received must also be considered. Advanced heart disease in general, and coronary artery disease in particular, appear to predispose patients to apparent digitalis toxicity at relatively lower serum or plasma levels.

Cardiac glycoside assay technics have also proven useful in various studies of the clinical pharmacology of digoxin, digitoxin, and ouabain. Handling of digoxin by patients on cardiopulmonary bypass has been assessed, and gastrointestinal absorption has been evaluated in normal subjects; poor and erratic absorption of the drug has been documented in patients with malabsorption syndromes. Potentially important drug-drug interactions of agents such as phenobarbital and phenylbutazone with digitoxin have been studied, as well as the effects of steroid-binding resins on digoxin and digitoxin metabolism. Studies of ouabain pharmacokineties by radioimmunoassay have demonstrated a plasma half-life of 21 hours, indicating that, as in the case of digoxin and digitoxin, half-life of serum or plasma concentration after establishment of blood-tissue equilibrium bears a close relationship to duration of clinical effect.
Evaluation of Left Ventricular Function by Echocardiography
Authors: FORTUIN NICHOLAS J. , HOOD WILLIAM P. , CRAIGE ERNEST
Published: June 2012

Ventricular minor-axis dimensions were measured by echocardiography at end-systole (S
8
) and end-diastole (S
D
) in five groups of patients: (I) normal; (II) mitral stenosis; (III) compensated volume overload; (IV) idiopathic hypertrophic subaortic stenosis; and (V) congestive heart failure. Cardiac pump function was evaluated by determination of left ventricular volumes and ejection fraction (EF) from the echographic dimensions using formulae previously reported. The mean velocity of circumferential fiber shortening (V
CF
), a parameter of cardiac muscle performance previously obtained only by invasive methods, was determined from the echographic dimensions by the formula:[See Equation in PDF File]. The duration of minor-axis shortening (dt) was measured directly from the echocardiogram.

Dimension and volume measurements in these groups of patients were similar to those reported in similar patients determined by angiographic methods. Measurement of the relative changes in echographic dimensions with systole (%ΔS), EF, and V
CF
allowed separation of patients with clinical heart failure (group V) from normal subjects (group I). Patients in group II had reduced values for these parameters compared to group I. Those in III did not differ significantly, and those in IV had increased values. In general, V
CF
, EF, and %ΔS showed similar trends, but individual patients sometimes differed. The findings reported here demonstrate the feasibility of evaluating ventricular function by a noninvasive method in a large group of ambulatory patients.
Coronary Collateral Circulation and Myocardial Blood Flow Reserve
Authors: KNOEBEL SUZANNE B. , MCHENRY PAUL L. , PHILLIPS JOHN F. , PAULETTO FEBREL J.
Published: June 2012

This study was undertaken to assess the effect of collateral circulation on myocardial blood flow (MBF) reserve (ability to increase myocardial blood flow with a stress that increases myocardial oxygen requirements). One hundred patients had MBF measured at rest and after isoproterenol. After classification by anatomic severity of coronary artery disease (CAI), the groups were further compared by presence or absence of collateral vessels, and whether the collaterals were intercoronary or bridge collaterals. Forty patients (group A) had no coronary artery disease demonstrated by cineangiography. The increase in MBF with isoproterenol for this group was 87% (
P
< 0.001). Fifteen patients (group B) had CAI of 175 or greater. These patients increased MBF 73% on infusion of isoproterenol, an insignificant difference from group A. Forty-five patients (group C) had CAI of 175 or less when an index of 300 represents no occlusive disease. Those with intercoronary collateral vessels (group C
1, 2
) were unable to increase MBF to the same extent as patients in groups A and B did. There was no difference between this group and those without collateral vessels and the same severity of disease. Fifteen patients with CAI of 175 or less (group C
3, 4
) had bridge collaterals and were able to increase MBF to a greater extent than those with no collaterals or with intercoronary collateral vessels. This same group of patients, in a parallel observation, showed less S-T-segment depression on treadmill exercise than patients with intercoronary collateral vessels.

The data suggest that intercoronary collateral vessels contribute insignificantly, statistically, to myocardial blood flow reserve. Bridge collaterals, however, do seem to contribute in selected patients.
Electrical Stimulation of the Heart in Patients with Ventricular Tachycardia
Authors: WELLENS HEIN J. , SCHUILENBURG REINIER M. , DURRER DIRK
Published: June 2012

The initiation and termination of tachycardias were studied in five patients who suffered from recurrent attacks of ventricular tachycardia. In four, coronary artery disease with old myocardial infarction was present. A ventricular tachycardia could be initiated in all patients by a single right ventricular premature beat given during regular driving of the right ventricle. The tachycardia could be terminated by a single right ventricular premature beat, or two right ventricular premature beats given in close succession. In four of our patients an early right ventricular premature beat was followed by the next QRS complex of the tachycardia after an interval shorter than compensatory. Our results favor reentry as the causal mechanism for the tachycardias in our patients. Possible pathways for circus reentry leading to ventricular tachycardia can theoretically be composed of (1) the bundle branches, (2) Purkinje fibers with or without adjacent ventricular myocardium, (3) infarcted or fibrotic ventricular tissue, and (4) combinations of (1), (2), and (3).
Chronic Hemolysis following Fascia Lata and Starr-Edwards Aortic Valve Replacement
Authors: DAVE KAMAL S. , MADAN CHAND K. , PAKRASHI BROJESH C. , ROBERTS BRYON E. , IONESCU MARIAN I.
Published: June 2012

Sixty-two patients were investigated for chronic intravascular hemolysis from 3 months to 6½ years following aortic valve replacement; 27 patients had Starr-Edwards prostheses and 35 fascia lata grafts.

The findings are suggestive of a significantly higher incidence and degree of hemolysis in patients with Starr-Edwards prostheses compared to those with fascia lata grafts. In both groups regurgitation was an important factor in producing hemolysis. In the absence of regurgitation fascia lata grafts do not produce significant hemolysis, while Starr-Edwards valves traumatize the red cells even in the absence of regurgitation. Starr-Edwards valves of small size are associated with hemolysis more often than larger ones are. Turbulent flow due to the obstructing ball is the probable mechanism of hemolysis in these patients. In most of the patients the degree of hemolysis appears to remain at the same level of activity. In rare instances, however, the hemolysis may regress. The mechanism for this is not clear. In a small number of patients, also, progressive hemolysis may necessitate removal and replacement of the valve.
Phenomenon of Supernormality in the Human Heart
Authors: MASSUMI RASHID A. , AMSTERDAM EZRA A. , MASON DEAN T.
Published: June 2012

This report documents five cases of supernormal (SN) conductivity in the sense of unexpected normalization of the previously existing bundle-branch block (BBB) and three cases of SN excitability in which impulses delivered to the ventricles propagated to the myocardium only during a well-defined interval in the cardiac cycles corresponding to the U waves of the preceding beat. In none of the patients could SN be abolished by atropine, suggesting absence of an important vagal role. In the five patients with SN conductivity there were three examples of right BBB in which spontaneous, as well as electrically induced premature atrial beats, were followed by normal QRS complexes only if they reached the right bundle during its SN phase. In the other two patients with bilateral BBB, strategically placed sinus P waves and electrically induced atrial impulses were conducted to the ventricles with normal P-His and His-Q intervals. Analysis of the electrocardiograms and His bundle electrograms indicated that SN conductivity resided in the bundle branches, and not in the A-V node. In one of two patients with bilateral BBB and SN conductivity in the right bundle branch, the SN-conducted beats occurred after both left and right ventricular escape beats, but were coupled to the preceding escape beats by longer intervals after left ventricular escape beats than after right ventricular escape beats. The difference was accounted for by the later activation of the right bundle branch when the preceding escape beat originated from the contralateral left ventricle. These observations favor an electrophysiologic explanation for the phenomenon of supernormality which is most probably related to the increased voltage of the transmembrane action potential in the period commonly known as the period of negative afterpotentials. This study provides no support for the hemodynamic or vagal theory of supernormality.
Gross Anatomy Associated with Patterns Called Left Posterior Hemiblock
Authors: STRICKLAND A. WADE , HORAN LEO G. , FLOWERS NANCY C.
Published: June 2012

From a compilation of 1411 gross dissections of the hearts from patients who had had recent electrocardiograms prior to death, 62 were found to have frontal QRS axes between +90 and +180°.

Thirty-eight exhibited an S
1
Q
3
R
3
pattern-the second screening criterion basic to consideration for the label of left posterior hemiblock (LPH). Twenty-two of these also had right ventricular free wall weights in excess of 70 g. Two others exhibited inferior myocardial infarction only. Of the remaining 14, six afforded mild clinical suspicion of increased hemodynamic loading of the right heart but did not have increased right ventricular weights. Four had right bundle-branch block (RBBB), and only one had a prolonged P-R interval.

The S
1
Q
3
R
3
pattern with right-axis deviation thus occurred in patients with or without right ventricular hypertrophy and with or without inferior wall myocardial infarction. Right bundle-branch block was a frequent occurrence in the spectrum of right-axis deviation (RAD) whether S
1
Q
3
R
3
was present or not.

The scatter of the frequent associates of RAD-inferior myocardial lesions, right ventricular hypertrophy, a clinical history of right ventricular loading diseases, and RBBB—suggests three alternative ways of viewing the S
1
Q
3
R
3
pattern with RAD: (1) LPH is
a
cause of S
1
Q
3
R
3
with RAD. It is a manifestation of left ventricular myocardial disease, but it may be a result of overt infarction, or may be mimicked by right ventricular disease. (2) LPH is
the
cause of S
1
Q
3
R
3
with RAD. It is the means by which diverse etiologies produce a distinctive electrocardiographic pattern (including left ventricular myocardial deficits, right ventricular enlargement, or a small group of unknown causes). (3) LPH is an artifact of convenience. Patients with RAD may or may not have S
1
Q
3
R
3
; they frequently have inferior wall myocardial infarction, right ventricular overload or enlargement, and RBBB.
Alteration of Glucose and Insulin Metabolism in Congenital Heart Disease
Authors: HAIT GERSHON , CORPUS MARINA , LAMARRE FRANCOIS R. , YUAN SHANG-HSIEN , KYPSON JINDRICH , CHENG GRACE
Published: June 2012

Children with left-to-right shunt, with and without congestive heart failure, were found to have impaired glucose tolerance tests (GTT). In cyanotic children normal levels of glucose were found in association with abnormally high levels of insulin following oral GTT. Several possible mechanisms are proposed to explain the different glucose tolerance alterations: (1) Suppression of insulin release appeared to partially explain the low levels of insulin in congestive heart failure. This suppression may be related to the high levels of circulating norepinephrine found in these patients. (2) Excessive clearance of insulin by the lung may also be responsible for the reduced arterial insulin levels in patients with left-to-right shunt, and underclearance of insulin for the abnormally higher arterial insulin levels in patients with right-to-left shunts in whom a significant amount of venous blood has bypassed the lung. (3) Hypoxia of the pancreas and the liver in cyanotic patients and those with congestive heart failure may explain the reduction of insulin levels in the hepatic vein following i.v. glucose tolerance tests. An excess production of a glucagonlike gastrointestinal factor in cyanotic children may partially explain the abnormally high levels of insulin following oral GTT.
Hemodynamics of Hypertension in Chronic End-Stage Renal Disease
Authors: KIM KWAN EUN , ONESTI GADDO , SCHWARTZ ALLAN B. , CHINITZ JOEL L. , SWARTZ CHARLES
Published: June 2012

This study was undertaken to define the hemodynamic changes in hypertension of chronic end-stage renal disease. Mean cardiac index in 75 uremic patients was higher (
P
< 0.001) than that of 42 normal volunteers while stroke index was not different from normals. The higher cardiac indices of uremic patients were accounted for by increased heart rates. Despite the significantly higher blood pressure in the uremics, their mean total peripheral resistance index was not different from that of normals.

The total group of 75 patients included 52 hypertensive and 23 normotensive uremics. Cardiac index, heart rate, and stroke index were the same in 52 hypertensive and 23 normotensive uremics while mean total peripheral resistance index of hypertensive uremics was higher (
P
< 0.001) than normotensive uremics. Therefore, the hypertension in end-stage renal disease is sustained by a high total peripheral resistance.

Bilateral nephrectomy in 12 hypertensive uremics resulted in no changes in cardiac index; a consistent decrease in blood pressure (
P
< 0.001) and a decrease in total peripheral resistance index (
P
< 0.001) occurred. Bilateral nephrectomy in eight additional uremics with malignant hypertension resulted in an actual increase in cardiac index (
P
< 0.001) with a consistent reduction in blood pressures (
P
< 0.001) and an even more dramatic decrease in total peripheral resistance (
P
< 0.001).

These findings imply that a vasopressor substance of renal origin increasing peripheral resistance is the major factor in the pathophysiology of renal hypertension in the late stage of its natural history.
Effects of Coronary Bypass Graft Occlusion on Left Ventricular Performance
Authors: ANDERSON RICHARD P.
Published: June 2012

High-fidelity recordings of left ventricular (LV) pressure and its corresponding first derivative (dP/dt), electrocardiogram, and systemic arterial pressure were obtained intraoperatively following insertion of aortocoronary saphenous vein bypass grafts in eight men. During sequential 3-min periods, the bypass grafts were, in turn, open, occluded by vascular clamps, and opened by releasing the clamps.

Peak dP/dt averaged 1342 mm Hg/sec before graft occlusion, fell to 1223 mm Hg/sec during occlusion, and rose following release of occlusion to 1373 mm Hg/sec. LV end-diastolic pressure (LVEDP) averaged 14.5 mm Hg before, 17.6 mm Hg during, and 16.1 mm Hg after graft occlusion. Arterial systolic and diastolic pressure and heart rate showed little change (
P
> 0.05) throughout the experiments. Left ventricular performance as gauged by peak dP/dt/LVEDP decreased an average of 25% (
P
< 0.001) during graft occlusion and returned to control levels following release of occlusion. Total vein graft blood flow, measured immediately before the occlusion experiments, averaged 164 ml/min. Good correlation was lacking between vein graft blood flow and performance changes during graft occlusion in individual patients.

Aortocoronary vein bypass grafts are capable of participating directly in the mechanical events of the cardiac cycle. Acute graft occlusion can impair, while restoration of graft flow can improve, left ventricular performance.
Supernormal Conduction in the Human Atria
Authors: AGHA ABDUL S. , CASTILLO CESAR A. , CASTELLANOS AGUSTIN , MYERBURG ROBERT J. , TESSLER MICHAEL P.
Published: June 2012

A supernormal period of intra- and interatrial conduction was observed in five patients during premature stimulation of various atrial sites with driving cycle lengths ranging between 500 and 600 msec. Electrograms were recorded with filtered, 1-mm apart, bipolar catheter electrodes placed in the high right atrium, coronary sinus, and midleft atrium. The supernormal period, which lasted from 90 to 140 msec, was located at the end of the relative refractory period. During this part of the cycle, the response
1
-response
2
(R
1
-R
2
) intervals were shorter than the corresponding St
1
-St
2
intervals. As in experiments performed with plunge electrodes, the conduction time of premature atrial responses was shorter than in late diastolic or driven beats. Although a mechanical origin (due to inevitable catheter movement produced with cardiac motion) can be invoked in the genesis of these changes, it is highly probable that supernormality was a true electrophysiologic event involving, predominantly, the specialized atrial tracts.
Evaluation of the Pulse-Contour Method of Determining Stroke Volume in Man
Authors: ALDERMAN EDWIN L. , BRANZI ANGELO , SANDERS WILLIAM , BROWN BYRON W. , HARRISON DONALD C.
Published: June 2012

The pulse-contour method for determining stroke volume has been employed as a continuous rapid method of monitoring the cardiovascular status of patients. Twenty-one patients with ischemic heart disease and 21 patients with mitral valve disease were subjected to a variety of hemodynamic interventions. These included exercise, isoproterenol infusion, and practolol, morphine or pentazocine administration. The pulse-contour estimations, using three different formulae derived by Warner, Kouchoukos, and Herd, were compared with indicator-dilution outputs. The pressure-pulse-contour computations were performed by a small on-line cardiac catheterization laboratory computer. A comparison of the results of the two methods for determining stroke volume yielded correlation coefficients ranging from 0.59 to 0.84. The better performing Warner formula yielded a coefficient of variation of about 20%. The type of hemodynamic interventions employed did not significantly affect the results using the pulse-contour method. This method yielded nearly as reliable results with the catheter positioned in the axillary artery as in the central aorta. Good results were obtained using the pulse-contour method in patients with atrial fibrillation as compared to those with sinus rhythm.

Although the correlation of the pulse-contour and indicator-dilution stroke volumes is high, the coefficient of variation is such that small changes in stroke volume cannot be accurately assessed by the pulse-contour method. However, the simplicity and rapidity of this method compared to determination of cardiac output by Fick or indicator-dilution methods makes it a potentially useful adjunct for monitoring critically ill patients.
Echocardiographic Diagnosis of Mitral Regurgitation due to Ruptured Chordae Tendineae
Authors: SWEATMAN THOMAS , SELZER ARTHUR , KAMAGAKI MASANOBU , COHN KEITH , Basford Judith
Published: June 2012

The echocardiographic findings from six patients with ruptured chordae tendineae from the posterial mitral valve leaflet and three with ruptured chordae from the anterior leaflet are reported; in all cases the diagnosis was later proven by open-heart surgery. The constellation of echocardiographic findings suggesting ruptured chordae tendineae to the posterior leaflet are: (1) The appearance of echoes within the left atrial chamber, representing prolapse of the posterior leaflet and flail chordae tendineae. This finding, although not consistently observed, is the most pathog-nomonic echocardiographic sign. (2) Increased amplitude of systolic excursion of the left atrial wall, in most cases associated with normal or only mildly increased left atrial diameter. (3) Recognition of thin, low-intensity (noncalcified) mitral valve leaflets. (4) The anterior leaflet may also manifest increased amplitude of motion, and may not coapt normally with the posterior leaflet in systole. (5) Increased amplitude of motion of the interventricular septum with an increased estimated stroke volume and normal-to-increased ejection fraction.

The findings suggestive of ruptured chordae tendineae to the anterior leaflet are: (1) A markedly increased amplitude of motion of the anterior mitral valve leaflet is evident. This leaflet appears to approach or touch the left ventricular septum in systole and the left atrial wall in diastole. (2) All of the findings of ruptured chordae to the posterior leaflet are also seen here, except for the observation of the posterior leaflet within the left atrial chamber.

This constellation of findings has not been seen in normal indiviuals, nor is it present in patients with mitral insufficiency proven to be due to other factors, such as papillary muscle dysfunction or rheumatic heart disease. Hence, this noninvasive technic enables one to diagnose accurately the presence of mitral regurgitation due to ruptured chordae tendineae.
A Noninvasive Technic for Determining Patency of Saphenous Vein Coronary Bypass Grafts
Authors: GOULD K. LANCE , MOZERSKY DAVID J. , HOKANSON D. EUGENE , BAKER DONALD W. , KENNEDY J. WARD , SUMNER DAVID S. , STRANDNESS D. EUGENE
Published: June 2012

A noninvasive method for determining patency of saphenous vein coronary bypass grafts has been developed in our laboratory. The system consists of a pulsed ultrasonic Doppler, a position-sensing arm for the Doppler transducer, a memory oscilloscope, an electrocardiogram, and strip-chart recorder. Patients are studied with the transducer in the suprasternal notch and intercostal spaces. Wherever flow is detected in the anterior mediastinum, a visible dot is stored on the oscilloscope screen at a point corresponding to the location of flow in the mediastinum. By repeated sampling at various depths a composite picture of a proximal section of graft is developed. Peak velocity flow signals from grafts occur during diastole distinguishing them from other arterial flow signals. Twenty-eight patients having 41 patent grafts were studied in a preliminary evaluation of the method. Three examples of angiograms with corresponding ultrasonic arteriograms demonstrate the feasibility and potential value of this new noninvasive technic for assessing patency of saphenous vein coronary bypass grafts.
Mitral Insufficiency Secondary to Aortic Valvular Bacterial Endocarditis
Authors: EDWARDS JESSE E.
Published: June 2012

The anterior leaflet of the mitral valve is partly continuous through a fibrous membrane with the aortic valve. Lying immediately subjacent to the aortic valve, the mitral valve and its chordae may become secondarily infected in instances of primary aortic valvular bacterial endocarditis. Destructive changes of the anterior mitral leaflet or mitral chordae may lead to mitral insufficiency. The latter may dominate the functional and clinical pictures. In some instances, when infection is overcome, the clinical picture may appear to be that of primary mitral valvular disease.
Ventricular Fibrillation Occurring on Arousal from Sleep by Auditory Stimuli
Authors: WELLENS HEIN J. J. , VERMEULEN AART , DURRER DIRK
Published: June 2012

A patient is described having syncopal attacks on being awakened from sleep by auditory stimuli. The electrocardiogram registered during these episodes showed Q-T-segment changes followed by ectopic ventricular activity and spontaneously ending attacks of ventricular fibrillation. Aside from the attacks, her ECG only showed abnormalities of the S-T segment with marked U waves. Hemodynamic and electrophysiologic studies showed no abnormalities. Coronary angiograms were normal. Following therapy with propranolol and diphenylhydantoin she has been free from syncopal episodes for the past 11 months. The mechanism responsible for the Q-T-segment changes and ventricular tachyarrhythmias is not understood.