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D K Murdock

Publications and source records attributed to D K Murdock.

At least 37 records · Page 2Linked to original sources
PubMed1988

Hemodynamic effects of contrast media during coronary angiography: a comparison of three nonionic agents to Hypaque-76.

Coronary angiography with standard ionic contrast media is associated with marked alterations in cardiac hemodynamics because of the depressant effects of the contrast media on cardiac contractility. Nonionic contrast media have been reported to produce less hemodynamic alteration than standard ionic contrast media. However, there is no information on how one nonionic media compares to another. Thus we compared the hemodynamic effects of three nonionic contrast media, Iopamidol (IOP), Iohexol (IOH), and Ioversol (IOV) to each other as well as to the standard ionic contrast media Hypaque-76 (H76). In 20 closed-chest anesthetized dogs, we recorded the maximal change in left ventricular systolic pressure (LVSP), mean aortic pressure, left ventricular diastolic pressure (LVDP), and left ventricular dp/dt during 10-cc left main coronary artery injections of H76, IOP, IOH, and IOV. The mean aortic pressure and LVSP decreased 36 +/- 17 mm Hg and 46 +/- 21 mm Hg with H76 but only 5 +/- 5 mm Hg and 6 +/- 5 mm Hg with IOP, 5 +/- 4 mm Hg and 6 +/- 6 mm Hg with IOH, and 5 +/- 4 mm Hg and 7 +/- 6 mm Hg with IOV (P less than 0.001). The LVDP increased 6 +/- 5.0 mm Hg with H76 but only 0.2 +/- 0.5 mm Hg with IOP, 0.2 +/- 0.3 mm Hg with IOH, and 0.5 +/- 1.0 mm Hg with IOV (P less than 0.001). The LV dp/dt decreased 545 +/- 261 mm Hg/sec with H76 but increased 886 +/- 477 mm Hg/sec with IOP, 910 +/- 96 mm Hg/sec with IOH, and 473 +/- 335 mm Hg/sec with IOV (P less than 0.001). Whereas each nonionic agent produced significantly less hemodynamic abnormalities than H76, there was no significant difference between any of the nonionic agents on any hemodynamic parameter. Thus, as compared to H76, these nonionic contrast media produced only trivial alterations in hemodynamics and LV dp/dt. These agents may be preferable in patients with LV dysfunction.

Angiography↗
PubMed1988

Differential hemodynamic effects of Hypaque-76 and Renografin-76 during coronary angiography: the role of calcium-binding additives.

Hypaque-76 (H76) and Renografin-76 (R76) are nearly identical ionic contrast media, except that R76 binds more calcium than H76 because of the presence of sodium citrate and EDTA in R76. To determine whether the calcium-binding additives in ionic contrast media contribute to the hemodynamic effects of contrast media during coronary angiography, left coronary angiography was performed in anesthetized dogs. In nine closed-chest dogs, 10 cc of H76 and R76 were injected in each dog in a blinded, randomized fashion. The effect of H76 and R76 on left ventricular systolic pressure (LVSP) and left ventricular diastolic pressure (LVDP), on mean aortic pressure (MAP), and on left ventricular (LV) dp/dt was recorded. Compared with H76, R76 produced a greater decrease in the LVSP (77 +/- 25 mmHg vs 48 +/- 17 mmHg P less than .05), MAP (72 +/- 24 mmHg vs 38 +/- 18 mmHg P less than .01), and LV dp/dt (747 +/- 87 mmHg/sec vs 460 +/- 81 mmHg/sec P less than .01). In nine additional open-chest dogs, left coronary angiography was performed 1 hour after occlusion of the proximal LAD coronary artery. Seven cc R76 produced a 35 +/- 15 mmHg decrease in LVSP, compared with 20 +/- 9 mmHg with H76 (P less than .01). The LV dp/dt decreased 720 +/- 387 mmHg/sec with R76, compared with 462 +/- 222 mmHg/sec with H76 (P less than 0.05). Thus, R76 produces significantly greater hemodynamic abnormalities than H76. Contrast media lacking calcium-binding agents may be preferable for coronary angiography.

Animals↗
PubMed1988

Contrast media-induced ventricular fibrillation. A comparison of Hypaque-76, Hexabrix, and Omnipaque.

Contrast media occasionally produce ventricular fibrillation during coronary angiography. We compared the fibrillatory propensity of the conventional ionic contrast medium, Hypaque-76 (H76) to the low osmolar ionic dimer Hexabrix (HB) and to the nonionic agent Omnipaque (OM) in 20 open chest anesthetized dogs. Intracoronary injection of 6 mL of contrast medium produced spontaneous ventricular fibrillation in four of ten dogs with H76, compared with two of ten with HB, and zero of ten with OM (P = .07). The induction of two premature beats by programmed stimulation of the myocardium during injection of 4 mL of contrast medium produced ventricular fibrillation in ten of ten dogs with H76, compared with three of ten with HB, and zero of ten with OM (P less than .001). Both H76 and HB produced ventricular fibrillation in ten of ten dogs when three premature beats were induced, compared with two of ten dogs with OM (P less than .001). Four mL H76 produced a 109 +/- 18 msec increase in the QT interval, compared with an 82 +/- 17 msec increase with HB, and a 45 +/- 12 msec increase with OM. We conclude that both low osmolar HB and OM are less fibrillatory than the conventional ionic medium H76, and that the nonionic medium OM is less fibrillatory than the ionic dimer contrast medium HB.

Angiography↗
PubMed1988

Effects of contrast media on the conducting system of the heart during coronary angiography. A comparison of Renografin-76 to Hypaque-76.

Electrocardiographic changes induced by ionic contrast media can cause complications during coronary angiography. A conduction delay through various parts of the heart is one factor in the genesis of asystole or ventricular fibrillation. Hypaque-76 (H76) and Renografin-76 (R76) are nearly identical ionic contrast media except that R76 binds more calcium than H76 because of the presence of sodium citrate and EDTA in R76. To determine whether the calcium binding additives in ionic contrast media contribute to the cardiac conduction abnormalities, we examined conduction time through the atrioventricular (AV) nodal tissue (via bipolar His bundle electrograms) and through the distal part of the conduction system (recording the QRS complex from the ECG) during coronary angiography. We injected 10 mL of H76 and R76 in 19 closed chest dogs in a blinded, randomized fashion during coronary angiography. The effects of H76 and R76 on heart rate, AH interval, HV interval, V interval and PR interval, and QRS complex duration were recorded. In 14 nonatrial pacing dogs, compared with H76, R76 produced a greater increase in the AV interval (32.9 +/- 6 milliseconds vs 12.4 +/- 2 milliseconds, P less than .01) and the PR interval (29.6 +/- 6 milliseconds vs 11.9 +/- 4 milliseconds, P less than .02). Additionally, the heart rate decreased 13.9 +/- 3.5 beats/minute from control with R76 compared with a decrease of 4.2 +/- 2.6 beats/minute from control with H76 (P less than .05). There was no significant difference between the prolongation of the HV interval and V interval, or QRS complex duration generated by R76 and H76.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1988

Coronary angiography during acute myocardial infarction in dogs: comparison of the hemodynamic effects of ionic and nonionic contrast media.

We compared the hemodynamic effects during coronary angiography of three nonionic contrast media, iopamidol, iohexol, and ioversol, with each other as well as with the standard ionic contrast medium containing 66% diatrizoate meglumine and 10% diatrizoate sodium (Hypaque-76) in the presence of a left anterior descending coronary artery occlusion in dogs. In 13 opened-chest anesthetized dogs, we recorded the maximal change in left ventricular systolic pressure (LVSP), mean aortic pressure (MAP), left ventricular diastolic pressure (LVDP) and rate of rise in left ventricular pressure (LV dp/dt) during left main coronary artery injections of 10 ml each of Hypaque-76, iopamidol, iohexol, and loversal 1 hour after left anterior descending coronary artery occlusion. The changes in LVSP and MAP were, respectively, -29 +/- 12 mm Hg and -21 +/- 11 mm Hg with Hypaque-76, 3 +/- 6.6 mm Hg and -0.2 +/- 3.6 mm Hg with iopamidol, 4.8 +/- 8.6 mm Hg and 0.5 +/- 4 mm Hg with iohexol, and -0.8 +/- 6 mm Hg and -1.5 +/- 33 mm Hg with ioversal (p less than 0.001). The change in LVDP was 5.4 +/- 4.4 mm Hg with Hypaque-76 but -1.5 +/- 3.1 mm Hg with iopamidol, -1.7 +/- 2.4 mm Hg with iohexol, and -0.5 +/- 2.5 mm Hg with ioversol (p less than 0.001). The LV dp/dt decreased 682 +/- 318 mm Hg/sec with Hypaque-76, but increased 412 +/- 297 mm Hg/sec with iopamidol, 350 +/- 214 mm Hg/sec with iohexol, and 293 +/- 191 mm Hg/sec with ioversol (p less than 0.001). Thus, each nonionic agent produced significantly fewer hemodynamic abnormalities than Hypaque-76. There was no significant difference between any of the nonionic agents on any hemodynamic parameter. These agents may be preferable in patients with acute myocardial infarction or significantly impaired myocardial function.

Acute Disease↗
PubMed1987

The effect of sodium on the fibrillatory propensity of nonionic contrast media.

Removing sodium from standard ionic contrast media markedly increases the incidence of ventricular fibrillation in patients undergoing coronary angiography. Newer nonionic contrast media, iopamidol, iohexol, and ioversol contain only trace amounts of sodium. To determine whether sodium attenuates or potentiates ventricular fibrillation from nonionic contrast media, we measured the prolongation in QT interval and performed programmed electrical stimulation with one, two and three extra ventricular stimuli in 40 dogs during 4-mL intracoronary injections of iopamidol, iohexol, and ioversol. Solutions of each contrast medium with added NaCl at concentrations of 0.225%, 0.45%, and 0.9% were compared with standard contrast media. The addition of NaCl markedly increased the amount of QT interval prolongation produced by each contrast medium. With iopamidol, the amount of QT interval prolongation was 40 +/- 11 msec with standard iopamidol, but was 58 +/- 11 msec with 0.225% NaCl/iopamidol, 84 +/- 17 msec with 0.45% NaCl/iopamidol, and 132 +/- 42 msec with 0.9% NaCl/iopamidol (P less than .001). Similar results were seen with iohexol and ioversol. Ventricular fibrillation was difficult to induce with standard solutions of these agents (even with three extra stimuli), but became progressively easier to induce when NaCl was added. Three extra stimuli produced ventricular fibrillation in zero of 11 dogs with standard iopamidol, zero of 11 with 0.225% NaCl/iopamidol, three of 11 with 0.45% NaCl/iopamidol, and eight of 11 with 0.9% NaCl/iopamidol (P less than .001). Similar results were observed with iohexol and ioversol. The addition of choline chloride or dextrose did not increase ventricular fibrillation and QT interval prolongation. It is concluded that standard preparations of nonionic contrast media have a very low fibrillatory propensity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Successful reversal of acute cardiac allograft rejection with OKT*3 monoclonal antibody.

The efficacy of OKT*3 monoclonal antibody in reversing acute cardiac allograft rejection was investigated in 10 cardiac transplant recipients aged 5 to 57 years (mean 34 +/- 18) and treated with the same induction and maintenance immunosuppression. Serial endomyocardial biopsies, right heart catheterization, and echocardiograms were performed for rejection surveillance. After intensified immunosuppression with equine antithymocyte globulins and steroids, nine patients showed persistent rejection (lymphocytic infiltration and myocyte necrosis). Conventional immunosuppression was contraindicated in one patient. OKT*3 (5 mg by intravenous push daily for 14 days) resulted in complete resolution of rejection in nine of 10 patients (90%). After therapy with OKT*3 mean right atrial and pulmonary arterial wedge pressure were significantly lower (9.1 +/- 4.0 vs 4.8 +/- 2.0 mm Hg and 13.4 +/- 4.3 vs 8.0 +/- 3.3 mm Hg, respectively; p less than .05). Cardiac index was doubled in two patients with rejection-induced cardiac dysfunction (1.5 vs 3.2 and 1.6 vs 2.7 liters/min/m2). Only two patients developed antibodies to OKT*3. Fever, nausea and headache occurred with the first three doses of OKT*3 and did not recur. One patient developed aseptic meningitis. OKT*3 effectively reverses refractory cardiac allograft rejection before the development of irreversible graft dysfunction. Patients who do not develop antibodies to OKT*3 can be retreated with this drug. Adverse reactions to OKT*3 are self-limited.

Acute Disease↗
PubMed1986

The response of patients with complex ventricular arrhythmias secondary to dilated cardiomyopathy to programmed electrical stimulation.

A prospective study was undertaken to assess the response of patients with idiopathic dilated cardiomyopathy to programmed electrical stimulation (PES). Fifteen patients undergoing evaluation of congestive heart failure were studied. All patients underwent cardiac catheterization and coronary angiography as well as endomyocardial biopsy to exclude known causes of heart failure. No patient had a history of syncope or sustained ventricular arrhythmias. All patients were found to have severe left ventricular dysfunction (mean ejection fraction 17%), as well as nonsustained ventricular tachycardia on ambulatory monitoring or exercise testing. A protocol using up to two premature stimuli and burst pacing, from two right ventricular sites, induced up to four repetitive ventricular responses but failed to induce a sustained ventricular arrhythmia in any patient. Patients with dilated cardiomyopathy, advanced ventricular arrhythmias, and depressed left ventricular function respond differently than do patients with coronary artery disease, advanced ventricular arrhythmias, and depressed left ventricular function, to PES. PES appears to have limited value in the evaluation of patients with dilated cardiomyopathy and nonsustained ventricular arrhythmias.

Adult↗
PubMed1986

Augmentation of cardiac output by external cardiac pacing: pacemaker-induced CPR.

Transthoracic cardiac pacing is frequently associated with simultaneous stimulation of skeletal muscle and nerves. We describe a patient in cardiogenic shock and complete heart block in whom the associated vigorous abdominal and chest muscle contractions caused by transthoracic cardiac pacing resulted in a marked augmentation of cardiac output and systemic blood pressure via a "CPR" effect.

Aged↗
PubMed1986

Pacemaker malfunction: fact or artifact?

In summary, the present examples illustrate how pacemaker malfunction can be simulated by the sources of artifact produced or detected by the monitoring equipment. This form of pseudopacemaker malfunction remains a common cause of mistaken diagnosis of pacemaker malfunction. A thorough understanding of the examples outlined above should help distinguish true pacemaker malfunction from pseudopacemaker malfunction produced by artifact.

Amplifiers, Electronic↗
PubMed1985

Ventricular fibrillation during coronary angiography: reduced incidence in man with contrast media lacking calcium binding additives.

The intracoronary injection of contrast media during coronary angiography occasionally results in ventricular fibrillation. Experimental studies have implicated the calcium sequestering agents, sodium citrate and EDTA in Renografin 76 (RG76), as contributing to this complication. Angiovist 370 (AV370) is a contrast medium similar to RG76 except that it contains disodium calcium EDTA instead of EDTA and sodium citrate. To determine if contrast media lacking sodium citrate and EDTA will result in a lower incidence of ventricular fibrillation in man, this investigation compared the incidence of contrast media-induced ventricular fibrillation in patients undergoing coronary angiography with RG76 to that with AV370. Group A consisted of 2,500 consecutive patients undergoing coronary angiography with RG76 and group B consisted of 2,000 subsequent consecutive patients in whom AV370 was employed as the contrast medium. There was no significant difference between groups A and B with respect to the volume of contrast media used per patient (153 +/- 49 ml vs 154 +/- 45ml), age (58.4 +/- 10 vs 58.6 +/- 10 years), sex (70% male vs 70% male), ejection fraction (59 +/- 17 vs 60 +/- 20), history of mitral valve disease (5.8% vs 7.1%), history of aortic valve disease (6.7% vs 6.5%), prior coronary artery bypass graft surgery (6.6% vs 7.3%), or extent of coronary artery disease. Fifteen episodes of contrast media-induced ventricular fibrillation occurred in group A (incidence 0.6%) whereas two episodes occurred in group B (incidence 0.1%) (p less than 0.02). Each patient was successfully defibrillated and no adverse sequelae resulted. Thus the present investigation suggests that the incidence of ventricular fibrillation during coronary angiography can be significantly decreased by using contrast media lacking sodium citrate and EDTA.

Aged↗
PubMed1985

Ventricular fibrillation during coronary angiography: an analysis of mechanisms.

To investigate the mechanisms of ventricular fibrillation (VF) during coronary angiography, we assessed ventricular automaticity, local QT intervals, local conduction characteristics, and the ability to induce arrhythmias with premature ventricular stimulation in 30 dogs after intracoronary injections of 4 to 6 cc of Renografin 76 (RG 76). Ventricular automaticity was measured in six dogs as the idioventricular escape rate following intense vagal stimulation and was unchanged (51 +/- 6 vs 52 +/- 6 bpm, p greater than 0.05) with 6 cc of RG 76. In addition, 8 of 10 injections of 6 cc of RG 76 produced VF at a heart rate of 200 bpm compared to only 2 of 10 injections at a heart rate of 80 bpm (p less than 0.05). Composite and bipolar plunge electrodes were placed in the region perfused by the left anterior descending coronary artery (LAD) and circumflex coronary artery to assess QT intervals and conduction characteristics. RG 76, 4cc, produced a 116 +/- 18 msec increase in the QT intervals recorded from the region perfused by the LAD, resulting in a marked dispersion in repolarization. Both local bipolar and composite electrograms showed minimal conduction delay, which rarely extended beyond the QRS of a lead II ECG during atrial paced rhythm. As premature beats (spontaneous or induced) conducted through the region of QT prolongation, marked conduction delay was recorded from bipolar electrograms, while composite electrograms recorded continuous fractionated electrical activity spanning the diastolic interval at the onset of VF.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗