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R M MacMillan

Publications and source records attributed to R M MacMillan.

At least 37 records · Page 2Linked to original sources
PubMed1986

Rapid acquisition computed tomographic assessment of left ventricular regional wall motion using a new long axis view.

A long axis view to demonstrate left ventricular regional wall motion was devised for the ultrafast CT scanner. The patients are positioned supine, head first, into the scanner. The scan table is slewed 20 degrees counter-clockwise in the horizontal plane without tilt. A bolus of contrast is injected via a median antecubital vein. Contiguous level R wave triggered cine studies are obtained during peak passage of contrast through the heart to image the entire left ventricular cavity. Fourteen patients had left ventricular wall motion compared by long axis CT and RAO 30 degrees single plane ventriculography at catheterization. In all cases, regional wall motion in comparable segments by both methods was in agreement. It is concluded that the ultrafast CT long axis view permits diagnosis of left ventricular regional wall motion abnormalities. This view images the apex and sections the interventricular septum and lateral free wall horizontally. Unlike conventional CT views, it is comparable to the RAO left ventriculogram.

Cardiac Catheterization↗
PubMed1986

Angiographic recognition of ostial left main coronary artery stenosis: case report.

Ostial left main coronary stenosis has a poor prognosis and increased mortality rate with coronary arteriography. Due to its anatomic location, visualization of the stenosis may be difficult. A high index of suspicion based upon only a few signs should prompt the physician to perform certain maneuvers to obtain the correct diagnosis. Four illustrative cases are presented and discussed.

Aged↗
PubMed1986

The functional and anatomic evaluation of the cardiovascular system with rapid-acquisition computed tomography (cine CT).

Cine CT combines the advantages of digital cross-sectional imaging with those of angiography. It provides vivid portrayal of complex anatomic relationships as well as important functional data not easily obtainable elsewhere, including quantitation of myocardial wall thickening and regional myocardial blood flow. The blood flow in major vessels following coronary artery bypass graft surgery and cardiac output have been quantified with accuracy. The future of cine CT will depend ultimately on controlled studies comparing this technique with other modalities, including echocardiography, magnetic resonance imaging, radionuclide angiocardiography, and contrast-enhanced catheter angiography.

Blood Flow Velocity↗
PubMed1985

Left ventricular function after elective aneurysmectomy.

Employing rest and exercise first-pass radionuclide angiography before and 3 months after surgery, we studied patients with hemodynamically stable left ventricular aneurysm (LVA) undergoing both coronary artery bypass surgery to relieve angina pectoris and elective aneurysmectomy. There were 15 patients, 14 men and 1 woman with a mean age of 54 +/- 7 years. All patients had anterior and/or apical LVA. After surgery the postexercise mean left ventricular ejection fraction (LVEF) for the whole group improved significantly (p less than 0.004) compared with the preoperative value, but the resting LVEF did not change. The duration of exercise improved (p less than 0.01) after surgery, but not the double product. However, based upon the preoperative LVEF response to exercise, two groups were seen: Group A (n = 5) had greater than or equal to 5% increase in their LVEF with exercise versus Group B (n = 10), who had less than 5% increase or a decrease in their LVEF. Postoperatively, Group A decreased their LVEF with exercise and failed to improve exercise capacity or double product. Postoperatively, Group B increased the LVEF by greater than or equal to 5% as well as increasing exercise capacity (p less than 0.01), and double product (p less than 0.03). Group A had lower preoperative LVEF than Group B (p less than 0.01) and larger LVA. Patients with hemodynamically stable LVA who require coronary artery bypass surgery for angina should not have aneurysmectomy. The presence of hemodynamically stable LVA is not a contraindication to deriving benefit from myocardial revascularization.

Adult↗
PubMed1985

Rest-exercise radionuclide angiographic assessment of left ventricular function in chronic aortic regurgitation: significance of serial studies in medically versus surgically treated groups.

Forty consecutive asymptomatic patients with chronic aortic regurgitation who underwent three serial yearly rest and postexercise radionuclide angiograms were compared with 27 consecutive patients with chronic aortic regurgitation and aortic valve replacement who were studied preoperatively, 3 and 15 months postoperatively. Patients were divided into four subgroups based upon the resting left ventricular ejection fraction and the functional reserve on the initial study. Of the 40 medically treated patients, 19 (47.5%) and 24 (60%) demonstrated a response at least one type lower at 12 months and 24 months, respectively. Initial functional reserve, initial duration of exercise, and the change in exercise duration during the 24 months was not associated with changes in resting or postexercise left ventricular ejection fraction. A seesaw pattern was observed between the resting and the postexercise left ventricular ejection fraction as ventricular function deteriorated. We observed in the surgical groups a reversal of the seesaw interaction between the resting and postexercise ejection fraction seen in the medical patients. In the surgical groups the left ventricular end-diastolic pressure, initial functional reserve, initial duration of exercise, and change in exercise duration postoperatively were not predictors of improvement in left ventricular function at 15 months. Comparing medical and surgical serial data, we suggest yearly radionuclide angiographic determination of rest left ventricular ejection fraction in asymptomatic patients with chronic aortic regurgitation. When the rest ejection fraction is less than 50%, exercise angiography should be performed to determine functional reserve. When functional reserve is also abnormal, surgery should be recommended.

Adolescent↗
PubMed1985

Correlates of prolonged HV conduction in aortic stenosis.

Forty-eight patients with predominant aortic stenosis underwent His bundle electrography (HBE) at the time of diagnostic catheterization. Patients were divided into four groups based upon severity of calcification of the aortic valve fluoroscopically as judged independently by three angiographers. Of 48 patients, three had no calcification, 11 had mild, 18 had moderate, and 16 had severe aortic valve calcification. No correlation was found between HV interval and severity of aortic valve calcification. Significant correlation was found between HV interval prolongation and aortic valve area (p less than 0.02), history of congestive heart failure (p less than 0.02), and increasing left ventricular end-diastolic pressure (p less than 0.05). Left ventricular ejection fraction less than 45% had greater likelihood of HV interval prolongation (p less than 0.01). No correlation was established between HV interval and age, aortic valve gradient, left ventricular peak systolic pressure, syncope, and coronary artery disease. Aortic valve area was the most significant independent predictor of HV prolongation, with history of congestive heart failure second. We conclude that HV interval prolongation in aortic stenosis with calcified valves is best predicted by evidence of declining left ventricular function rather than severity of aortic valve calcification.

Adult↗
PubMed1985

Esophageal P-synchronous pacing.

An esophageal electrode can be employed to provide atrial sensing which then can be used to change from temporary right ventricular (VVI) pacing to P-synchronous (VAT) pacing. Two cases of postoperative aortic valve replacement, each with new complete heart block (CHB) and dopamine dependency, are presented. In both cases, establishment of P-synchronous pacing resulted in improved hemodynamic status characterized by successful weaning from dopamine and maintenance of adequate cardiac output (CO).

Aged↗
PubMed1985

Radionuclide angiography in the quantitation of mitral regurgitation.

First pass radionuclide angiography (RA) was used to assess its ability to detect and quantitate the presence of left-sided regurgitation due to isolated mitral regurgitation (MR). In this study the nuclear regurgitant fraction (NRF) obtained from first pass RA was correlated with the results of contrast ventriculography (CV) in 50 patients, 18 with and 32 without MR. The correlation between CV and RA in the confirmation and quantification of isolated MR revealed a sensitivity of 100 percent and a specificity of 97 percent in patients with LVEF greater than or equal to 35 percent.

Adult↗
PubMed1984

Emergency guide wire pacing: new methods for rapid conversion of a cardiac catheter into a pacemaker.

We developed a new electrode to convert rapidly a previously inserted pulmonary artery or left ventricular catheter into a pacemaker. One method of doing this is by withdrawal of the pulmonary artery catheter from the pulmonary artery to the right ventricle by pressure control, and a Teflon-coated guide wire, stripped of 5 mm of insulation at its tip, is advanced through the catheter to contact the endocardium. In the second method, the pacing electrode is advanced through the distal lumen of the catheter while it is positioned within the pulmonary artery and withdrawn into the right ventricle while pacing. Finally, a third method involves advancement of the guide wire electrode into the left ventricle through a pigtail catheter. To pace, the guide wire electrode is connected to the cathode of a pacemaker referenced to a skin electrode. We paced 10 of 10 right heart cardiac catheterization, intra- and postoperative surgery patients by methods 1 and 2, and 4 of 4 left heart catheterization patients by method 3. Thresholds (mean +/- SEM) for guide wire pacing were: right ventricle 1.52 +/- 0.4 mA; left ventricle 1.33 +/- 0.1 mA. Guide wire pacing is rapid, reliable, and requires little operator skill. Our indications for guide wire pacing are: 1) emergency right ventricular pacing in operative or intensive care unit patients with unexpected bradyarrhythmias who have an indwelling pulmonary artery catheter; and 2) emergency left ventricular pacing in left heart cardiac catheterization patients with contrast-induced bradyarrhythmias.

Bradycardia↗
PubMed1983

Coronary artery obstruction due to blunt chest trauma with residual angina pectoris.

A 41-year-old man developed persistent angina pectoris following blunt trauma to his chest. Three months after the injury coronary angiography demonstrated 80% obstruction of the mid-left anterior descending coronary artery. There was no evidence of atherosclerosis in the remaining coronary arteries. Therefore the assumption is made that blunt trauma can induce incomplete coronary occlusion resulting in classic angina pectoris in apparently otherwise normal coronary arteries. The suggested mechanism of injury to the coronary vessel is either intimal tear and/or subintimal hemorrhage with incomplete luminal thrombosis.

Adult↗
PubMed1978

Congenital coronary arteriovenous fistula: a diagnostic challenge.

This report describes a case of coronary arteriovenous (A-V) fistula involving both the right and the left coronary arteries. The venous component of the two circulations combines into a single channel that empties into the left ventricle just below the mitral valve.

Arteriovenous Fistula↗