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Biomedical subjects

L S Griffith

Publications and source records attributed to L S Griffith.

At least 91 records · Page 5Linked to original sources
PubMed1978

Coronary angiography and left ventriculography in survivors of transmural and nontransmural myocardial infarction.

Recent studies have suggested a similar prognosis for patients with transmural myocardial infarction and nontransmural myocardial infarction despite a smaller infarct size in the latter patients estimated by creatine phosphokinase (CPK). Thirty-one patients with transmural myocardial infarction and 17 patients with nontransmural myocardial infarction as defined by electrocardiographic criteria underwent coronary angiography and left ventriculography from 10 to 24 days after they had an acute myocardial infarction. Forty-three of these 48 patients were asymptomatic following their myocardial infarction. When compared to patients with nontransmural myocardial infarction, those with transmural myocardial infarction had greater peak CPK levels, 1,090 +/- 210 versus 290 +/- 60 IU (p less than 0.01). There was no difference in prevalence of single, double or triple vessel coronary artery disease, mean number of coronary arteries 50 per cent narrowed (2.0 +/- 0.2 versus 2.0 +/- 0.2), near total or total occlusions, coronary score (Friesinger) (7.9 +/- 0.6 versus 8.2 +/- 0.7), left ventricular ejection fraction (48 +/- 2 versus 53 +/- 4), or per cent of akinetic-dyskinetic myocardial segments (66 of 242 [27 per cent] versus 32 of 132 [24 per cent]) between two groups. The similar extent of coronary artery narrowing and degree of left ventricular dysfunction may explain the similar prognosis for patients with transmural myocardial infarction and those with nontransmural myocardial infarction despite differences in enzymatically estimated acute infarct size.

Adult↗
PubMed1977

Thallium-201 myocardial perfusion imaging at rest and during exercise. Comparative sensitivity to electrocardiography in coronary artery disease.

The sensitivity of myocardial perfusion imaging (MPI) using thallium-201 injected both at rest and during peak exercise was compared to simultaneously recorded 12 lead electrocardiography (ECG) for the detection of transient ischemia in 20 normal subjects and 63 patients with coronary artery disease (CAD). No significant perfusion defects or ECG changes were seen on either the rest or exercise studies in any of the normal subjects. Fifty-six percent of patients with CAD developed new perfusion defects with exercise compared to 38% who developed ischemic ST-segment depression (P less than 0.02). However, when chest pain and/or ST depression were considered indices of ischemia, the sensitivity of exercise testing and thallium-201 MPI was similar. The increased sensitivity of MPI compared to ST-segment depression on the ECG was due to patients with baseline ECG abnormalities and those who failed to achieve 85% of predicted maximum heart rate with exercise. Analysis of the exercise results according to the extent of coronary artery disease revealed a progressive increase in both positive ECGs and MPI with the number of vessels involved. In patients with single vessel disease the MPI was more sensitive than the ECG (P less than 0.02). The combination of the rest and exercise ECG, MPI and chest pain during exercise failed to identify 11% of patients with CAD. Exercise thallium-201 MPI is a useful adjunct to conventional exercise testing particularly when evaluating patients with abnormal resting ECGs, those who develop ventricular conduction defects of arrhythmias during exercise, and those who fail to achieve their predicted heart rate because of fatigue or breathlessness.

Adult↗
PubMed1977

Left ventricular and coronary angiographic anatomy. Relationship to ventricular irritability in the late hospital phase of acute myocardial infarction.

Late hospital phase ventricular arrhythmias in acute myocardial infarction (MI) have been associated with a high incidence of sudden death following hospital discharge. Thirty-eight patients were studied 10-24 days following onset of symptoms of MI. Each patient had a 24-hour ambulatory ECG tape recording and left ventricular and coronary angiography performed. Patients with complicated ventricular arrhythmias (multiform, coupled, R on T VPCs or ventricular tachycardia), when compared to those with uncomplicated ventricular arrhythmias (unifocal or no VPCs), had a greater number of proximally narrowed major coronary arteries (P less than 0.001), a higher coronary "score" (P less than 0.001), a greater incidence of previous myocardial infarction (P less than 0.005), a greater percentage of abnormal left ventricular segments 86% vs 69% (P less than 0.001) and lower ejection fractions. These data suggest that late hospital phase survivors of MI with complicated ventricular arrhythmias have more extensive coronary artery disease with greater left ventricular dysfunction than survivors with uncomplicated ventricular arrhythmias. This more extensive disease may result in increased areas of ischemic myocardium and may help explain the refractoriness of these arrhythmias to pharmacologic therapy.

Acute Disease↗
PubMed1977

Correlation of coronary arteriograms and left ventriculograms with postmortem studies.

To assess the accuracy of angiographic determinations of disease of coronary arteries and left ventricular myocardium we compared clinical with postmortem coronary arteriograms and left ventriculograms with myocardial pathology in 28 patients, all of whom died postoperatively and within three months of angiography; 19 had ischemic heart disease, four valvular heart disease, and five both. Comparison of pre and postmortem lumenal occlusion in 315 epicardial coronary segments, excluding those operated upon, showed greater than 50% narrowing discrepancies in 21 (7%). Significant coronary artery lesions were overestimated in six and underestimated in 15. Of the six overestimations, three appeared to be due to coronary spasm; of the 15 underestimations, 12 were due to overlapping images; six discrepancies were unexplained. Comparison of wall motion in 140 ventriculogram segments with myocardial pathology, excluding any post-study or perioperative injury, showed good correlation of reduced motion with 48 (34%) infarcted and 10 (7%) aneurysmal segments. However, 58 (41%) other segments had poor or absent ventriculogram motion, with structurally normal myocardium and patent coronary artery supply; 19 were on infarct margins and 39 in dilated or hypertrophied hearts. Thus, premortem coronary arteriographic occlusions generally indicate atherosclerotic narrowing; but decreased or absent segmental wall motion frequently does not indicate a myocardial lesion. It may be attributable to ischemia in the distribution of a critically narrowed coronary artery or it could be due to abnormal ventricular topography.

Adult↗
PubMed1977

Occlusive changes at the coronary artery--bypass graft anastomosis. Morphologic study of 95 grafts.

Ninety-five bypass graft anastomoses in 52 patients dying up to 4 years after direct coronary revascularization were studied at autopsy by angiograms and serial histologic sectioning of the graft-artery anastomosis. When new coronary occlusions and narrowings occurred, they were adjacent to either the proximal or distal ends of the anastomosis and were due to compression or loss of circumference of the arterial lumen (40 per cent), thrombus formation (40 per cent), mural dissection of the coronary wall (8 per cent) or the combination of compression and thrombosis (12 per cent). Small coronary artery diameter, local atheromas, and extension of the arteriotomy into a branch vessel were significant factors predisposing to occlusive changes. The findings emphasize the importance of careful artery selection for bypass, the need to avoid local vascular disease and branch-points, and the technical difficulties encountered in the presence of local vascular lesions or small coronary arteries.

Adult↗
PubMed1975

The "angina-producing" myocardial segment: An approach to the interpretation of results of coronary bypass surgery.

The first 153 cases of saphenous vein aortocoronary bypass surgery performed at The Johns Hopkins Hospital were reviewed. Eighty-eight percent of the 140 late survivors reported significant symptomatic improvement. Seventy-one unselected patients consented to complete reevaluation at a mean interval of 6.1 months postoperatively. Vein bypass patency in this group was 66 percent. Eighty-two percent of these 71 patients had improved performance on electrocardiographic stress testing. There were no significant differences between hemodynamic status on pre- and postoperative studies regardless of the status of vein bypass patency. Repeat coronary angiography revealed a 30 percent incidence of new total occlusions of the intrinsic coronary circulation. Segmental wall motion on ventriculography was improved in 12 percent, unchanged in 50 percent and decreased in 38 percent of the segments analyzed. Localized electrocardiographic changes compatible with myocardial damage developed in the immediate postoperative period in 45 of these patients (63 percent); in 38 of the 45, these changes corresponded to new angiographic abnormalities. Physiologic mechanisms underlying symptomatic improvement were sought by identification of an "angina-producing" myocardial segment. In most instances, alleviation of angina could be related to either: (1) a patent bypass graft into an unchanged intrinsic coronary artery with presumed increased blood flow to the distal coronary segment, or (2) occlusion of the bypass graft and the corresponding coronary artery with probable infarction of previously ischemic myocardium. Current criteria for the selection of patients undergoing coronary bypass surgery are reviewed in the light of these findings. It is concluded that relief of disabling angina is the major indication for surgery. Prevention of myocardial infarction and improvement in left ventricular function are at present less reliable objectives.

Angina Pectoris↗