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Biomedical subjects

P J Scanlon

Publications and source records attributed to P J Scanlon.

At least 19 recordsLinked to original sources
PubMed1992

The clinical significance of exercise-induced bundle branch block.

Exercise-induced bundle branch block is an uncommon electrocardiographic entity said to be associated with coronary heart disease. Thirty-seven patients were studied to determine if exercise hemodynamics and stress/rest thallium scans could identify those patients with coronary heart disease. Eighteen patients of the study group also had coronary angiography. Group I (n = 17) with normal thallium scans and group II (n = 20) with abnormal thallium scans had significantly different maximal heart rate, maximal blood pressure, and double product in exercise as well as duration of exercise. Clinical evaluation of the patient study group permitted a division of the patients into two subgroups: group A, atypical chest pain or abnormal exercise electrocardiogram (n = 12), and group B, definite or probable angina (n = 25). Group B patients had significantly more abnormal thallium scans (17/25) than group A patients (3/12) (p less than 0.04). When compared to coronary angiography, stress/rest thallium scans had a predictive accuracy of 85% for coronary heart disease. While exercise-induced ST-segment depression and R wave amplitude increases are not specific in exercise-induced bundle branch block, exercise hemodynamics and stress/rest thallium scans can help diagnose patients with coronary heart disease. These test findings added to a clinical evaluation permit a more accurate stratification of the patients and indicate which patients need further study.

Bundle-Branch Block↗
PubMed1992

Effects of intracoronary administration of contrast media on myocardial high-energy phosphate. A comparison of sodium meglumine diatrizoate and iohexol.

Myocardial ATP, ADP, and AMP were measured from cardiac biopsy in 11 dogs after intracoronary injection of 6 mL of sodium-meglumine diatrizoate (SMD), iohexol (IOH), or 0.9% sodium chloride (NaCl), and in three of the dogs at baseline before any injection. The ATP at baseline and after SMD, IOH, and 0.9% NaCl were 5.39 +/- 0.41, 3.72 +/- 0.70, 5.52 +/- 0.82, and 5.44 +/- 1.40 mumol/g wet weight, respectively. There were significant differences between SMD and IOH (P less than .02), and between SMD and 0.9% NaCl (P less than .05). The energy charge of SMD was 0.82 +/- 0.08, which differed from 0.89 +/- 0.02 for NaCl or 0.9 +/- 0.05 for baseline (P less than .05), but not from 0.85 +/- 0.04 for IOH. In conclusion, diatrizoate caused significant depletions in ATP stores in comparison with iohexol, but there was no significant difference with respect to energy charge. Nonionic contrast media would be preferable for coronary arteriography in patients whose high-energy stores might be depleted from severe ischemia.

Adenosine Diphosphate↗
PubMed1991

Effects of intracoronary administration of contrast media on coronary hemodynamics in a canine post ischemic reperfusion model.

Hemodynamic changes due to intracoronary injections of nonionic contrast medium Omnipaque-350 (OM), ionic dimer Hexabrix (HB), and ionic contrast medium Renografin-76 (R76) were compared at baseline and during reperfusion after a 30-minute left anterior descending coronary artery (LAD) occlusion. In 11 open chest, anesthetized, and atrially paced dogs, 4 ml of either OM, HB, R76, or 0.9% NaCl were injected into the carotid-LAD bypass system. Coronary blood flow (CBF) and coronary vascular resistance (CVR) were measured before, during and after the intracoronary injection. The maximal hyperemic change (in percentage) from the preinjection value of CBF and CVR were calculated. The results at baseline and during reperfusion for CBF were: 104 +/- 14% vs. 85 +/- 10% for OM (NS); 76 +/- 11% vs. 39 +/- 9% for R76 (p less than 0.05); 57 +/- 8% vs. 33 +/- 5% for HB (P less than 0.05); and 30 +/- 7% vs. 9 +/- 4% for 0.9% NaCl (p less than 0.05). Consequently, the hyperemic changes of CVR at baseline and during reperfusion were: -49 +/- 3 vs. -42 +/- 4% for OM (NS); -44 +/- 3% vs. -24 +/- 6% for R76 (p less than 0.01); -36 +/- 3% vs. -24 +/- 4% for HB (p less than 0.05); and -18 +/- 4% vs. -7 +/- 3% for 0.9% NaCl (p less than 0.05). Thus, ischemia and reperfusion significantly dampened the coronary hemodynamic and vascular response to R76, HB, and 0.9% NaCl but not to OM. The preserved coronary vascular reserve with high flow in this canine post-ischemic reperfusion model may explain the advantage of nonionic over ionic contrast media used in emergency coronary angiography following thrombolysis.

Animals↗
PubMed1991

Failure of adjuvant heparin to reduce myocardial ischemia in the early treatment of patients with unstable angina.

Although the efficacy of long-term administration of antithrombotic agents in unstable angina has been established, short-term effects on myocardial ischemia are unknown. A retrospective analysis was performed in 47 patients undergoing three-channel continuous ST segment monitoring as part of a multicenter trial using esmolol in unstable angina, in which 20 patients received a continuous heparin infusion during the initial assessment of chest pain. Concomitant medications included calcium channel blockers, beta-adrenergic blockers, nitrates, and aspirin in the majority of patients. Clinical variables between the heparin and no heparin groups were similar, except for fewer males and fewer total artery occlusions in the heparin group. No significant differences in the incidence or duration of ischemia were found in a 36 +/- 16 hour monitoring period. Forty percent of the heparin group had 35 episodes of ischemia with a mean of 11 +/- 10 minutes per episode and a total ischemic time of 48 +/- 39 minutes per patient with ischemia. Forty-four percent of the no heparin group had 47 episodes of ischemia with a mean of 13 +/- 13 minutes per episode and a total ischemic time of 58 +/- 47 minutes per patient with ischemia. Multiple linear regression analysis to adjust for intergroup differences did not alter the results. Eighty-five percent of all episodes were asymptomatic. Clinical events, such as episodes of chest pain, emergency coronary arteriography, or coronary revascularization, were also similar between groups. Thus the short-term administration of heparin did not alter the incidence or duration of ischemia in patients with unstable angina.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1991

Effect of cardiopulmonary support on regional and global left ventricular function during transient coronary occlusion.

The ability of extracorporeal cardiopulmonary support (CPS) to unload the left ventricle and reduce ischemic dysfunction during transient coronary occlusion was studied in 10 anesthetized dogs. Three serial 60-second circumflex coronary artery occlusions were performed with CPS initiated only during the second occlusion. CPS significantly reduced preocclusion systolic blood pressure, blood pressure x heart rate double-product, circumflex blood flow, left ventricular end-diastolic pressure (LVEDP), peak negative dP/dt, and left ventricular systolic thickening. Circumflex occlusion caused changes in LVEDP and left ventricular wall thickening that were similar regardless of the presence or absence of CPS. These data suggest that CPS unloads the left ventricle during myocardial ischemia but does not prevent regional or global myocardial dysfunction.

Angioplasty, Balloon, Coronary↗
PubMed1991

Alterations in transesophageal pulsed Doppler indexes of filling of the left ventricle after pericardiotomy.

The impact of pericardial constraint on patterns of left ventricular filling was measured by transesophageal pulsed Doppler echocardiography in 30 patients undergoing elective nonvalvular cardiac surgery. Peak early left ventricular filling velocity increased from 0.52 +/- 0.11 to 0.56 +/- 0.15 m/s (p less than 0.05) and early left ventricular filling fraction increased from 60 +/- 9% to 65 +/- 9% (p less than 0.005) after pericardiotomy. The study group was retrospectively subdivided into two groups based on the prepericardiotomy mean right atrial pressure, an index of intrapericardial pressure and hence pericardial constraint. In 13 patients with a mean right atrial pressure less than 6 mm Hg, no significant changes in early left ventricular filling were evident after pericardiotomy. In 17 patients with a mean right atrial pressure greater than or equal to 6 mm Hg indicative of a greater degree of pericardial constraint before pericardiotomy, significant increases in peak early filling velocity (0.52 +/- 0.13 to 0.57 +/- 0.19 m/s, p less than 0.05), peak early filling rate (4.29 +/- 0.67 to 4.66 +/- 0.86 stroke volumes/s, p less than 0.05) and early left ventricular filling fraction (57 +/- 7% to 63 +/- 8%, p less than 0.001) were measured after pericardiotomy. Thus, the pericardium does constrain early left ventricular filling and its effects are more pronounced in patients with an elevated right atrial pressure.

Aged↗
PubMed1991

Transesophageal echocardiographic demonstration of distinct mechanisms for right to left shunting across a patent foramen ovale in the absence of pulmonary hypertension.

The optimal visualization of the atrial septum and fossa ovalis by transesophageal echocardiography was utilized to demonstrate saline contrast transit across the atrial septum and to relate it to the motion of the flap valve (septum primum) of the fossa ovalis. In three cases, three distinct mechanisms of right to left interatrial shunting in the absence of right ventricular systolic hypertension were identified: 1) transient spontaneous reversal of the left to right atrial pressure differential with each cardiac cycle; 2) sustained elevation of right atrial pressure above left atrial pressure induced by respiratory maneuvers; and 3) aberrant flow redirection across the foramen ovale due to a large right atrial mass. Any of these three mechanisms may be operative during paradoxic embolism in the absence of elevation of right ventricular pressures.

Aged↗
PubMed1990

Risk of thromboembolism during diagnostic and interventional cardiac procedures with nonionic contrast media.

To investigate the relationship between clot formation and thromboembolism, canine blood was withdrawn into catheter-syringe or catheter-steerable wire systems containing either contrast medium or normal saline as used in debubbling techniques. The contrast media used were iohexol, iopamidol, ioxaglate, and diatrizoate. Without the use of heparin, after a 30-minute incubation, blood clots were harvested from all catheter-syringe systems except those with diatrizoate and from all catheter-steerable wire systems. Significantly more blood clot was harvested from the catheter-steerable wire system. With use of heparinized blood, no clot was found in any system. Twelve dogs that underwent coronary angiography were divided into two groups; one received heparin (5,000 IU) and the other did not. Thromboembolism occurred in all nonheparinized dogs that underwent angiography with iohexol or iopamidol but not in any other group. The authors found that in a dog model nonionic contrast media are more thrombogenic than ionic contrast media, especially in the catheter-steerable wire system. The blood clot in the catheters is associated with thromboembolism during angiography. The authors maintain that in this setting, blood clotting and thromboembolism with nonionic agents can be eliminated with heparin.

Animals↗
PubMed1990

Electrophysiological testing and nonsustained ventricular tachycardia. Use and limitations in patients with coronary artery disease and impaired ventricular function.

Electrophysiological testing was performed in 100 consecutive patients with spontaneous asymptomatic nonsustained ventricular tachycardia, chronic coronary artery disease, and ejection fraction of less than 40%. Fifty-seven patients without inducible sustained ventricular arrhythmias were discharged on no antiarrhythmic therapy. Sustained monomorphic ventricular tachycardia was induced in 37 patients, and polymorphic ventricular tachycardia or ventricular fibrillation was induced in six patients. Of the 43 patients with inducible sustained ventricular arrhythmias, three had spontaneous cardiac arrest during serial drug testing and were excluded from further analysis. Twenty patients were discharged on drug therapy, resulting in suppression of inducible sustained ventricular arrhythmias. The remaining 20 patients with persistently inducible sustained arrhythmias were discharged on drug therapy, resulting in maximal rate slowing of the induced tachycardia. During a mean follow-up of 16.7 months, there were 10 recurrent cardiac arrests or sudden deaths. The 1- and 2-year actuarial incidence of these events was 2% and 6%, respectively, in patients without inducible sustained ventricular arrhythmias; 0% and 11%, respectively, in patients in whom inducible arrhythmias were suppressed; and 34% and 50%, respectively, in patients with persistently inducible sustained ventricular arrhythmias. Multivariate Cox analysis identified only the persistence of inducible sustained ventricular arrhythmias as a significant independent predictor of sudden death or recurrent sustained arrhythmias (p less than 0.001; relative risk, 3.5; 95% confidence intervals, 2.1-4.9). In this population, therapeutic intervention to prevent sudden death is unnecessary in patients without inducible sustained ventricular arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Cardiac lymphoma associated with superior vena caval syndrome and cardiac tamponade: case history.

A sixty-three-year-old patient with malignant histiocytic lymphoma of the heart presented with both superior vena cava syndrome and cardiac tamponade. A two-dimensional echocardiogram showed a large tumor mass in the right atrium and pericardial effusion with right ventricular compression. Superior and inferior vena cavagrams disclosed a lobulated tumor located in the right atrium that extended into and obstructed the superior vena cava. After the pericardial effusion was drained and the diagnosis was established, the patient was irradiated and given chemotherapy with resolution of the tamponade and superior vena cava obstruction.

Cardiac Tamponade↗
PubMed1990

The effect of sodium on hemodynamic changes during coronary angiography with nonionic contrast media.

To investigate the effect of sodium on cardiac hemodynamics, sodium chloride was added to nonionic contrast media to a 0.9% concentration and was compared with the standard media iohexol, iopamidol, and ioversol. Left coronary angiography was performed in 10 closed-chest, atrial-paced dogs with 10 ml injections of each preparation in a randomized and blinded fashion. The maximum changes in left ventricular systolic pressure, mean aortic pressure, left ventricular and diastolic pressure, and maximal rise of left ventricular pressure were measured. The left ventricular systolic pressure and mean aortic pressure decreased by 17 +/- 7 mm Hg and by 12 +/- 5 mm Hg with iohexol plus 0.9% NaCl, but only by 5 +/- 4 mm Hg and by 4 +/- 3 mm Hg with iohexol alone (p less than 0.001). The left ventricular and end diastolic pressure increased by 2.2 +/- 0.6 mm Hg with iohexol plus 0.9% NaCl, but did not change with iohexol alone (p less than 0.001). Left ventricular dp/dt decreased by 204 +/- 161 mm Hg/sec with iohexol plus 0.9% NaCl but increased by 392 +/- 122 mm Hg/sec with iohexol alone (p less than 0.001). Similar results were obtained from experiments with iopamidol versus iopamidol plus 0.9% NaCl and ioversol versus ioversol plus 0.9% NaCl. Ioversol plus 5% dextrose or ioversol plus 2.1% choline chloride (isomolar to ioversol plus 0.9% NaCl) produced a significant increase in left ventricular systolic pressure and left ventricular dp/dt (versus ioversol plus 0.9% NaCl, p less than 0.001). Thus, sodium, but not the osmolality or chloride, contributed to the negative inotropic effect of the contrast media.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effects of ionic and nonionic contrast media on bradyarrhythmia during coronary angiography: a comparison of Renografin-76, Hypaque-76, and Isovue-370.

Contrast media occasionally produce bradyarrhythmias defined as a 25% decrease in heart rate and/or developing atrioventricular block during coronary angiography. Twelve left coronary angiographies and seven right coronary angiographies were performed with 10 ml of diatrizoate meglumine and diatrizoate sodium (Renografin-76 [R76] or Hypaque [H76]) or iopamidol (Isovue 370 [ISO]) in a blinded randomized fashion. Heart rate decreased significantly from 135 +/- 5 to 120 +/- 5 beats/min (p less than 0.001) with R76, to 127 +/- 7 beats/min (p less than 0.01) with H76, and to 130 +/- 6 beats/min (p less than 0.05) with ISO in left coronary angiographies; more profound decrease was observed in right coronary angiographies from 134 +/- 4 to 87 +/- 18 beats/min (p less than 0.001) with R76, to 99 +/- 14 beats/min (p less than 0.001) with H76, and to 125 +/- 7 beats/min (p less than 0.01) with ISO. In 12 left coronary angiographies bradyarrhythmia was observed in five cases with R76, two with H76, and none with ISO. In seven right coronary angiographies it occurred in six with R76, three with H76, and none with ISO. The differences in the incidence of bradyarrhythmia between R76 and ISO were significant during left and right coronary angiographies (p less than 0.05 and p less than 0.01, respectively). Thus ionic contrast media produced more marked bradyarrhythmias than nonionic contrast media in coronary angiography, especially R76. Right coronary angiography resulted in more profound bradyarrhythmias than left coronary angiographies. This study suggested that nonionic contrast media (ISO) might be preferable to ionic contrast media (R76 or H76) for coronary arteriography.

Angiography↗
PubMed1989

Hemodynamic abnormalities during coronary angiography: comparison of Hypaque-76, Hexabrix, and Omnipaque-350.

The hemodynamic effects induced by coronary angiography in dogs with low osmolar ionic dimer Hexabrix (HB) and nonionic Omnipaque-350 (OM) were compared to the standard ionic contrast medium, Hypaque-76 (H76), both in the normal heart and in one with simulated severe cardiac disease. Left coronary angiography was performed in 12 "normal" closed-chest dogs with 10-cc injections of H76, HB, and OM in a randomized, blinded fashion. The maximal change in the left ventricular (LV) systolic pressure (SP), mean aortic pressure (MAP), left ventricular end diastolic pressure (LVEDP), and LV dp/dt were recorded. The LVSP and MAP fell 30 +/- 3 mm Hg and 26 +/- 4 mm Hg with H76, 22 +/- 2 mm Hg and 19 +/- 2 mm Hg with HB, and 7 +/- 1.5 mm Hg and 5 +/- 1 mm Hg with OM (P less than .001). The LVEDP increased 4.8 +/- 0.5 mm Hg with H76, 3 +/- 0.5 mm Hg with HB, but only 0.2 mm Hg with OM (P less than .001). The LV dp/dt decreased 392 +/- 63 mm Hg/sec with H76 and 235 +/- 21 mm Hg/sec with HB, but increased 411 +/- 50 mm Hg with OM (P less than .001). In eight additional open-chest dogs, left coronary angiography was performed 1 hr after occlusion of the proximal LAD coronary artery and in the presence of a critical circumflex coronary artery (CX) stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1989

The potential risk of thrombosis during coronary angiography using nonionic contrast media.

The influence of contrast media on coagulation has an important association with thromboembolic complication during coronary angiography. In this study, whole blood was methodically mixed with nonionic contrast medium, Iohexol (IOH), conventional ionic contrast medium, Hypaque-76 (H76), and low osmolar ionic dimer Hexabrix (HB) in vitro. The thrombotic propensity of contrast agents can be evaluated by measuring the clot formation of the mixtures. The experiments were repeated with whole blood after systemic heparinization. In the in vitro study, 5 ml of canine (N = 10) and 3 ml of human (N = 11) whole blood was incubated for 30 min in glass tubes with equal volumes of IOH, H76, HB, and 0.9% NaCl before heparinization. Clot formation with IOH and 0.9% NaCl were seen both in dogs (4.0 +/- 0.7 gm and 5.6 +/- 0.8 gm) and in patients (1.4 +/- 0.9 gm and 2.9 +/- 1.3 gm), whereas no clot was seen with H76 or XB. Following heparinization, no clot was visualized in any mixture of whole blood with contrast media or 0.9% NaCl. Similar results were observed in the catheter-syringe system with canine blood (N = 11) mixed with the contrast agents. Blood clots found in 15 min and 30 min of IOH were 0.07 +/- 0.08 gm and 0.44 +/- 0.20 gm (P less than 0.01) and of NaCl were 0.29 +/- 0.37 gm and 0.69 +/- 0.38 gm (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1989

Long term survival of class IV heart failure patients treated with oral amrinone.

The purpose of this study was to evaluate the effect of amrinone on the survival of a group of 51 Class IV congestive heart failure patients as well as changes in exercise capacity, hemodynamics, and clinical status. In those 22 patients able to exercise before treatment with amrinone, exercise duration increased from 4.15 minutes to 6.58 minutes on the treadmill. In those 19 patients first treated with intravenous amrinone, there was an increase in cardiac index from 1.9 to 2.6 L/min/m2. Thirty seven patients (72%) died in the follow-up period, most in the first four months. In this group of Class IV heart failure patients, there were two subsets of patients: one with a stable course (Group I) and one with a malignant course (Group II). The Group II patients accounted for much of the mortality in the follow-up. Patients with coronary artery disease did worse than patients with idiopathic dilated cardiomyopathies. There was no evidence that amrinone shortened or prolonged the survival of these Class IV patients.

Aged↗
PubMed1989

The mechanism and significance of ventricularization of intracoronary pressure during coronary angiography.

Ventricularization of pressure during coronary angiography has been said to identify the presence of left main coronary artery disease, but the hemodynamic features and the mechanism of this process have not been studied. Twenty consecutive patients with ventricularization were identified prospectively in our laboratory. Four patients had a discrete ostial left main stenosis and 16 patients had stenosis of the entire length of the left main coronary artery. The degree of pressure drop upon cannulation of the diseased left main coronary artery was highly variable; the systolic pressure decreased by 9 to 94 mm Hg, and the diastolic pressure decreased by 6 to 60 mm Hg. The morphology of the ventricularized pressure was distinct. It had a presystolic deflection resembling an a wave. The upstroke of this waveform was slower and the downstroke was steeper than that of the aortic pressure. An identical waveform was observed in dogs after partial occlusion of the left main coronary artery with a balloon-tipped catheter. The waveform of the so-called ventricularized pressure is derived from the aortic pressure, which is altered by its transmission across the left main coronary stenosis. The appearance of ventricularization is an important clue to the presence of left main coronary artery disease.

Aged↗
PubMed1989

Constrictive pericarditis after cardiac surgery.

Forty-five patients were identified as having constrictive pericarditis after cardiac surgery. The mean patient age was 61 years (range, 40 to 77 years). Twenty-three of 37 patients with adequate clinical information were reported to have had a diagnosis of postpericardiotomy syndrome after the original surgery. The mean interval from original surgery to presentation with constriction was 23.4 months (range, 1 to 204 months). Computerized tomography was helpful in establishing a diagnosis of constriction in 23 of 29 patients (79%). Bypass graft patency was 93% (85 of 91 grafts). Severe pulmonary hypertension (pulmonary artery systolic pressure greater than or equal to 60 mm Hg) was present in nine patients; 8 had coexistent valvular disease (seven cases of mitral valve disease, and aortic valve disease in one). Thirty-seven of the 45 patients underwent pericardial stripping, 28 of whom experienced marked symptomatic improvement. One patient had persistent right heart failure, which was not documented to be secondary to constriction. Four patients had persistent constrictive physiologic conditions. Three of these patients had more extensive pericardial stripping and showed clinical improvement. Four patients (11%) died within 30 days of stripping. Eight patients received medical therapy alone. The decision to treat patients medically was based either on favorable response to medical therapy (five patients), or poor general clinical status.

Coronary Artery Bypass↗