Ronald Danzig’s research while affiliated with Cedars-Sinai Medical Center and other places

What is this page?


This page lists works of an author who doesn't have a ResearchGate profile or hasn't added the works to their profile yet. It is automatically generated from public (personal) data to further our legitimate goal of comprehensive and accurate scientific recordkeeping. If you are this author and want this page removed, please let us know.

Publications (17)


Variability in response to norepinephrine in acute myocardial infarction
  • Article

January 1974

·

12 Reads

·

15 Citations

The American Journal of Cardiology

Edward Abrams

·

·

Kanu Chatterjee

·

[...]

·

H.J.C. Swan

Twenty-seven patients with acute myocardial infarction were studied by infusion of graded levels of norepinephrine at rates of 1 to 3, 3 to 5, 5 to 8 and 8 to 10 μg/min. Twelve patients subsequently died of pump failure during hospitalization. Control levels of stroke work produced excellent separation between survivors and nonsurvivors. The magnitude of maximal stroke work response during norepinephrine infusion in the two groups was also significantly different, but did not further separate the groups. However, the maximal percent change in stroke work in the two groups was similar, thus suggesting that, even in the presence of large infarcts, the remaining viable myocardium remains responsive to inotropic agents. Qualitatively the response of survivors and nonsurvivors was similar at low dose rates, but at a rate of 8 to 10 μg/min, survivors exhibited predominantly an increase in stroke volume with little change in peripheral vascular resistance, whereas nonsurvivors showed predominantly an increase in peripheral vascular resistance with little change in stroke volume. We conclude that the initial level of ventricular function determines both the nature and magnitude of response to inotropic agents in acute myocardial infarction. Clinically, the usefulness of norepinephrine in this disease may be limited, since patients most likely to receive the drug would be expected to respond with a small increase in flow and a significant increase in afterload.


Assessment of Sinus Node Function in Patients with the Sick Sinus Syndrome

November 1972

·

44 Reads

·

195 Citations

Circulation

Thirty-one patients with symptomatic sinus node dysfunction were evaluated with electrocardiograms, Holter monitor recordings, exercise, isoproterenol infusions, atropine administration, Valsalva maneuvers, carotid sinus massage, and overdrive pacing. Four basic clinical subsets were recognized: (1) carotid sinus hypersensitivity (2) bradycardia-tachycardia syndrome, (3) episodic sinus arrest, and (4) persistent symptomatic sinus bradycardia. The study group demonstrated a normal heart rate response to exercise and isoproterenol infusion (%Δ = +95 exercise, +144 isoproterenol) in the face of diminished responsiveness to atropine administration (%Δ = +23). Marked carotid sinus hypersensitivity was demonstrated in eight patients, and four patients demonstrated slight abnormalities during performance of Valsalva maneuvers. Significant suppression of sinus node dysfunction was observed following atrial overdrive in the study group (postpacing pause = 3087 ± 464 msec) as compared to patients without significant sinus node function (postpacing pause = 1073 ± 63 msec) ( P < 0.001). In patients with intact V-A conduction, ventricular overdrive also resulted in sinus node suppression (postpacing pause = 1901 ± 357 msec). There was a marked decrease in the degree of sinus node depression following atropine administration. Ten of 31 patients demonstrated various degrees of A-V block following atrial pacing at rates less than 100 beats/min. It is concluded that the present methods of evaluation of sinus function, especially sinus node recovery time following overdrive pacing, may prove of value in the investigation of patients with syncope of unknown etiology.




Lown-Ganong-Levine Syndrome: A Study Using His Bundle Electrograms

November 1971

·

20 Reads

·

49 Citations

Circulation

His bundle recordings were obtained in three patients with histories of recurrent supraventricular tachycardias and electrocardiograms demonstrating a short P-R interval with a normal QRS (the Lown-Ganong-Levine syndrome). The His bundle electrograms obtained during sinus rhythm demonstrated a normal A-H (atrium-to-His bundle) time in one patient and a low normal A-H time in two patients. The H-V (His bundle-to-ventricle) time was short in all three patients. Atrial pacing in two patients produced an attenuated degree of prolongation of the A-H time without a change in conduction distal to the proximal His bundle. The probable mechanisms of accelerated conduction in these three patients include: (1) partial A-V nodal bypass via (a) the posterior intenodal tract or (b) functional bypass fibers within the A-V node; and (2) accelerated conduction within the A-V conduction system distal to the A-V node.


Increase in threshold to ventricular activation related to atrial contraction. A possible example of "Wedensky inhibition"

November 1971

·

17 Reads

·

9 Citations

American Heart Journal

First and second degree pacemaker-ventricular block and second degree exit block of a junctional pacemaker are demonstrated in relationship to atrial depolarization in a 55-year-old man with acute inferior myocardial infarction and impaired atrioventricular conduction. It is proposed that atrial depolarization resulted in a transient increase in threshold of excitation distal to the area of block, and thus represents a possible example of Wedensky inhibition.


Dlastolic Pressure-Volume Relationship in the Canine Left Ventricle

October 1971

·

125 Reads

·

178 Citations

Circulation Research

Analysis of the passive pressure-volume filling curve of the left ventricle demonstrates that heart size and ventricular geometry exert major effects on the pressure-volume curve in the absence of changes in intrinsic muscle stiffness. Because the pressure-volume relationship is curvilinear, both quantitative and qualitative comparison of pressure-volume curves from different hearts is difficult. In the fresh isolated canine left ventricle, the pressure-volume relation was found to be almost perfectly exponential throughout a range of filling pressures from 5 to 30 mm Hg. Therefore, a precise linear and quantitative expression of the pressure-volume relation (dP/dV=aP+b) was developed (r=0.995). The effect of isolated changes in either initial ventricular volume (mean δa=3.1%) or ventricular geometry (mean δa=27.1%) upon the slope, or a constant of this function was small in comparison to changes induced by rigor mortis (mean δa =45%). It was concluded that the a constant was primarily affected by changes in left ventricular wall stiffness. In this manner, comparison of the pressure-volume relationship from different hearts is possible, and the contribution of changes in wall stiffness may be quantified.


Evaluation of Sino-atrial Node Function in Man by Overdrive Suppression

August 1971

·

21 Reads

·

373 Citations

Circulation

Sino-atrial node (SAN) function was evaluated in 46 patients, three of whom had the sick sinus syndrome. Patients were paced from the right atrium for 15 to 180 sec at rates of 90, 110, 130, and 150 beats/min. The rapid cessation of pacing was associated with suppression of the SAN at all paced rates and at all durations of pacing. The observed pause was terminated by a sinus beat in all instances. The duration of pacing had little influence on the duration of the observed pause. The pause increased as the pacing rate was increased until, at a rate of 150 beats/min, a marked decrease in the pause was noted. Atropine (1.5-3.0 mg iv) diminished but did not eliminate the SAN suppression. Subthreshold pacing did not suppress SAN function. Three patients with sick sinus syndrome had a greater degree of SAN suppression than normal patients (4732 ± 415 msec [SSS] M ± sem; 1041 ± 56 msec for normal patients). The determination of the duration of the pause following cessation of atrial pacing provides a technique for recognition of abnormalities of SAN function.


Acute myocardial infarction in man. Comparative hemodynamic effects of norepinephrine and glucagon

July 1971

·

17 Reads

·

24 Citations

The American Journal of Cardiology

The comparative hemodynamic effects of glucagon and graded doses of norepinephrine were examined in 7 subjects with acute myocardial infarction and various degrees of associated left ventricular failure. Glucagon (70 μg/kg) produced a 23 percent increase in cardiac index and a 15 percent decrease in peripheral vascular resistance, with no significant increase in tension-time index. Norepinephrine increased cardiac output 16 percent at a dose of 8 μg/min, but also produced a significant increase in the tension-time index (15 percent). The difference between these 2 agents relates to directionally opposite effects upon peripheral vascular resistance. Thus, glucagon may offer theoretical advantages over norepinephrine in the treatment of acute myocardial infarction and left ventricular failure since it produces the same increase in cardiac output for a smaller increase in tension-time index, a major determinant of myocardial oxygen consumption.


TABLE 3 Haemodynamic effects of 70 [Lg./kg. glucagon in ten subjects 
Haemodynamic effects of glucagon during acute myocardial infarction with left ventricular failure in man
  • Article
  • Full-text available

April 1971

·

29 Reads

·

33 Citations

Heart

Download

Citations (13)


... There is no good evidence that digitalis, or other cardiac glycosides, are useful inotropic agents in the treatment of pump failure unless the underlying cardiac rhythm is atrial fibrillation (Swan et al., 1969). ...

Reference:

Cardiogenic shock and the hemodynamic effects of arrhythmias
Current Status of Treatment of Power Failure of the Heart in Acute Myocardial Infarction with Drugs and Blood Volume Replacement
  • Citing Article
  • November 1969

Circulation

... Negli anni successivi, lo stesso gruppo pubblicò numerosi articoli sull'uso di questo tipo di catetere a scopi di studio, diagnostici o per verificare gli effetti emodinamici di farmaci, documentandone la praticità d'uso e l'utilità clinica [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] . ...

Variability in response to norepinephrine in acute myocardial infarction
  • Citing Article
  • January 1974

The American Journal of Cardiology

... The advent of techniques of intracardiac recording and stimulation has allowed analysis of the syndrome in great detail. It is now generally accepted that the short PR interval is the result of conduction in a partial or complete AV nodal bypass (Durrer et al., 1970; Castellanos et al., 1971; Mandel et al., 1971). ...

Lown-Ganong-Levine syndrome
  • Citing Article
  • June 1972

Circulation

... As a cholinolytic agent, atropine exerts a positive chronotropic and dromotropic effect, thereby accelerating sinus rate and improving conduction in the AV node. It is usually administered intravenously at a dose of 0.04 mg/kg, under continuous ECG recording for 15 min [43]. An increase in sinus rate ≥ 25% or a sinus rate ≥ 90 bpm in the first 15 min after infusion is considered a positive response. ...

Assessment of Sinus Node Function in Patients with the Sick Sinus Syndrome
  • Citing Article
  • November 1972

Circulation

... Figure 1C describes transition of LV hemodynamics from normal LV function to the severely impaired LV function seen in CS. The decreased myocardial contractility caused by an acute insult (CS) is reflected by the decreasing slope of end-systolic elastance (Ees) [8] (depicted as red arrow a), which results in a smaller stroke volume (b to b') despite higher left ventricular end-diastolic volume and pressure (LVEDV and LVEDP, respectively, depicted as black arrow c), a situation explained by the non-linear end-diastolic pressure-volume relationship (EDPVR) [9]. Figure 1D shows the principal changes in LV hemodynamics caused by the application of VA-ECMO for CS. ...

Dlastolic Pressure-Volume Relationship in the Canine Left Ventricle
  • Citing Article
  • October 1971

Circulation Research

... Studies using prolonged glucagon infusions (.1 hour) of 2 to 7.5 mg/h for an average of 48 to 118 hours (94-97) resulted in no change or even decreased heart rates in patients suffering from heart failure. Other studies otherwise comparable to the above using bolus glucagon observed no effects on heart rate (88,(98)(99)(100). Furthermore, a study on healthy volunteers receiving much lower glucagon infusion rates of 5 and 10 ng/kg/min for 60 minutes observed an average heart rate reduction by 8% and 6% from baseline (101). ...

Acute myocardial infarction in man. Comparative hemodynamic effects of norepinephrine and glucagon
  • Citing Article
  • July 1971

The American Journal of Cardiology

... It is rare pre-excitation condition and characterized by a short PQ interval (< 120 ms), a normal or inverted P wave, and a QRS complex of normal morphology and duration. The combination of the above features with paroxysmal SVTs, episodes of palpitation, giddiness, dyspnea, anxiety, angina, and the complaint of fatigue accompanied by characteristic changes on ECG (short PR), but not atrial brillation or utter are suggestive of LGL syndrome, which comprises the 17% of cases with short PQ interval (1,7). ...

Lown-Ganong-Levine Syndrome: A Study Using His Bundle Electrograms
  • Citing Article
  • November 1971

Circulation

... If it is initiated after occlusion, the oxygen would not be able to reach the ischaemic myocardium, as mice lack native coronary collaterals [127]. However, it is known that augmentation of the fraction of inspired oxygen (FiO 2 ) does not elevate O 2 delivery in patients who are not hypoxemic [117]. In addition, increased FiO 2 has not been found to benefit STEMI patients, possibly due to secondary effects on blood redistribution, as supplemental oxygen causes coronary and systemic vasoconstriction [87,116]. ...

Correcting arterial hypoxemia by oxygen therapy in patients with acute myocardial infarction. Effect on ventilation and hemodynamics
  • Citing Article
  • January 1970

The American Journal of Cardiology

... Myocardial infarction (MI) is considered a highly prevalent disease in the western countries (Mozaffarian et al., 2016); it results from the interruption of blood flow in the coronary arteries, which causes hypoxia and tissue injury (Sukumalchantra et al., 1970). The causes of MI are diverse, and both environmental factors and hormonal factors can influence its development. ...

The Mechanism of Arterial Hypoxemia in Acute Myocardial Infarction
  • Citing Article
  • May 1970

Circulation