Sven Paulin

First-pass nuclear magnetic resonance imaging studies using gadolinium-DTPA in patients with coronary artery disease

Nuclear magnetic resonance (NMR) imaging has been shown to accurately portray cardiac anatomy and function. To investigate the potential of NMR imaging for the assessment of coronary stenosis in patients with chest pain, ultrafast NMR imaging in conjunction with a T1 (longitudinal relaxation time) contrast agent was performed in 17 patients with chest pain who had undergone cardiac catheterization. These included 12 patients with significant coronary artery stenoses and 4 who underwent repeat NMR study after myocardial revascularization. Cardiac images at rest were obtained during rapid intravenous injection of gadolinium-DTPA (0.04 mM/kg). Electrocardiographic-gated images were acquired over 380 ms, with repetitive images obtained every 3 to 4 s. After contrast injection, there was pronounced signal enhancement in the right ventricular cavity, followed by enhancement in the left ventricular cavity and myocardium. Regional myocardium perfused by a diseased vessel demonstrated a lower peak signal intensity (p = 0.001) and lower rate of signal increase (p = 0.001) than did myocardium perfused by coronary arteries without stenosis. Repeat NMR study after revascularization showed an increase in peak signal intensity (p less than 0.002). These results demonstrate the clinical potential of dynamic gadolinium-DTPA-enhanced NMR imaging for the assessment of coronary artery disease in patients with chest pain. In combination with anatomic and functional NMR imaging, this technique has the potential to provide a comprehensive noninvasive cardiac evaluation of patients with suspected coronary artery disease.

Myocardial Salvage after Intracoronary Thrombolysis with Streptokinase in Acute Myocardial Infarction

Nine patients with acute myocardial infarction had cardiac catheterization and intracoronary infusions of streptokinase 2.3 to 4.3 hours (mean, 3.5) after the onset of symptoms. Occluded coronary arteries were opened within approximately 20 minutes in all patients, but reocclusion occurred in one patient. The immediate effect of thrombolysis on myocardial salvage was assessed with the intracoronary injection of thallium-201. Improved regional perfusion, indicating myocardial salvage after recanalization, was observed in seven of the nine patients. One patient, who had also sustained a nontransmural infarction one week before, had no change after thrombolysis. In the ninth patient, recanalization of a coronary artery was followed by reocclusion and worsening of the myocardial-perfusion defect. Intracoronary thallium-201 studies two weeks and three months after streptokinase infusion in two patients were unchanged in comparison with scintiscans performed 1.5 hours after thrombolysis. These short-term observations suggest that recanalization of obstructed coronary arteries after intracoronary thrombolysis can salvage jeopardized myocardium, However, evaluation of the long-term effects of this procedure on survival and myocardial function will require controlled clinical trials.

Computerized image analysis for quantitative measurement of vessel diameter from cineangiograms.

Subjective estimates of the angiographic severity of coronary artery stenoses show variability and inaccuracy. We therefore tested the accuracy of a newly developed computerized image analysis system for quantitating vessel diameter from cineangiograms. Fourteen cylindrical phantoms of known diameter were filled with contrast medium and filmed over a wide range of clinically relevant radiographic conditions in order to develop regression equations that related computer-derived to anatomic diameters. Computer measurements of vessel diameter were unaffected by vessel size, magnification, focal spot size, thickness of scattering medium, kilovolt peak, or location within the radiographic field, but a correction factor was necessary for a small but significant (p less than .01) linear dependence on contrast medium concentration. The accuracy of computerized vessel diameter measurements ranged between +/- 59 and +/- 137 mu for all conditions except for rapid vessel motion and contrast medium concentrations of 50% or less meglumine diatrizoate (Renografin 76), both of which resulted in reduced accuracy as well as in the inability to locate lumen edges of vessels less than 1 mm in diameter.

Leg phlebography: the incidence, nature and modification of undesirable side effects.

A prospective study was performed to elucidate the side effects of contrast medium phlebography for the diagnosis of deep vein thrombophlebitis (DVTP). The phelbograms were obtained with the patient in a semi-erect position, with an average dose of 125 ml of contrast medium infused continuously over 7-12 min. Renografin 60, or the same agent diluted to three-quarter strength, was used. The major side effects were pain during the study and a symptom complex resembling DVTP starting 12-36 hours after the study. Both were more common with the standard contrast medium (pain: 59.0% vs. 30.0%; delayed reaction: 24.0% vs. 7.5%), although the percentage of positive studies was unchanged (about 35.0%). Side effects were more frequent and severe than previously thought, but their incidence can readily be lowered.

In vivo coronary angioscopy.

The feasibility of in vivo coronary angioscopy was tested utilizing a 1.8 mm angioscope in vessels where blood had been replaced by optically clear liquids, including a new perfluorocarbon emulsion. After trials in postmortem canine and human coronary arteries, in vivo intraluminal visualization was accomplished in the dog with a catheterization technique and in patients during open heart surgery. The results demonstrate the feasibility and potential clinical usefulness of direct visualization of intravascular anatomy and disease, analogous to endoscopy of other organ systems.

Role of the Coronary Collateral Circulation in the Preservation of Left Ventricular Function

An angiographic assessment of the coronary arteries, the presence and quality of arterial collateralization and segmental left ventricular (LV) wall motion indicated that (a) in the presence of total or subtotal obstruction of a coronary artery, there was a significantly higher incidence of normal motion (p less than 0.001) if the segment of LV wall was supplied by good rather than poor collaterals, and (b) normal wall motion with good arterial collateralization was not associated with abnormal Q waves. It is concluded that a positive correlation exists between the quality of collateral filling and the preservation of LV wall motion in the area supplied.

Medically refractory unstable angina pectoris. I. Long-term follow-up of patients undergoing intraaortic balloon counterpulsation and operation.

Of 82 patients with medically refractory unstable angina pectoris seen between October 1972 and January 1978, 60 patients underwent a combination of intraaortic balloon pump counterpulsation, cardiac catheterization and coronary revascularization. Most patients had atherosclerotic involvement of the vessels of the anterior left ventricular wall, 48 patients (80 percent) had abnormalities of left ventricular wall contraction and 22 patients (36 percent) had evidence of acute myocardial injury. One operative and one late death occurred. The perioperative infarction rate was 5 percent. Survivors, followed up for 3 to 63 months (mean 31 months), have done remarkably well; 77 percent are considered employable,and more than 90 percent are in functional class I or II.

Treatment of preinfarction angina with intraaortic balloon counterpulsation and surgery

Abstract Sixteen patients with preinfarction angina unresponsive to medical therapy were treated by Counterpulsation with the intraaortic balloon pump. Chest pain and electrocardiographic changes were abolished or significantly decreased in all but one patient. Counterpulsation reduced peak systolic blood pressure, but had little effect on pulmonary capillary wedge pressure or cardiac output. Coronary anatomy was then defined by coronary angiography. Significant obstructive atherosclerosis of the main left or left anterior descending coronary artery was present in all but one patient. All patients underwent coronary revascularization by saphenous vein aortocoronary bypass graft. Fifteen of 16 patients survived the operation. All survivors are clinically improved, and 13 are completely asymptomatic from 1 to 20 months postoperatively.

Coronary blood flow in man and its relation to the coronary arteriogram.

Abstract Coronary flow was measured by injection of radioactive xenon into the aortic root and registration of the clearance curve in coronary sinus blood. Double determinations at rest were performed in 17 patients and showed good reproducibility. The values were in good agreement with those published earlier. Values for coronary blood flow were related to the degree of coronary heart disease established by coronary arteriogram. No difference in coronary flow was found between patients without detectable disease and patients with advanced coronary heart disease.

Intracoronary thallium-201 scintigraphy after thrombolytic therapy for acute myocardial infarction compared with 10 and 100 day intravenous thallium-201 scintigraphy

Thallium-201 imaging has been utilized to estimate myocardial salvage after thrombolytic therapy for acute myocardial infarction. However, results from recent animal studies have suggested that as a result of reactive hyperemia and delayed necrosis, thallium-201 imaging may overestimate myocardial salvage. To determine whether early overestimation of salvage occurs in humans, intracoronary thallium-201 scans 1 hour after thrombolytic therapy were compared with intravenous thallium-201 scans obtained approximately 10 and 100 days after myocardial infarction in 29 patients. In 10 patients with angiographic evidence of coronary reperfusion, immediate improvement in thallium defects and no interim clinical events, there was no change in imaging in the follow-up studies. Of nine patients with coronary reperfusion but no initial improvement of perfusion defects, none showed worsening of defects in the follow-up images. Six of these patients demonstrated subsequent improvement at either 10 or 100 days after infarction. Seven of 10 patients with neither early evidence of reperfusion nor improvement in perfusion defects had improvement of infarct-related perfusion defects, and none showed worsening. In conclusion, serial scanning at 10 and 100 days after infarction in patients with no subsequent clinical events showed no worsening of the perfusion image compared with images obtained in acute studies. Therefore, there is no evidence that thallium-201 imaging performed early in patients with acute myocardial infarction overestimates improvement.