John M. Lewis

Assessment of myocardial perfusion in humans by contrast echocardiography. I: Evaluation of regional coronary reserve by peak contrast intensity

Myocardial contrast echocardiography was performed during coronary angiography with 2 ml of sonicated meglumine diatrizoate sodium 76% (meglumine) in 40 patients (ranging in age from 25 to 79 years) before and 10 to 15 s after intracoronary injection of papaverine, 8 mg into the right coronary artery (n = 43) and 10 mg into the left (n = 46). The same protocol was repeated in 17 patients 5 to 10 min after completion of coronary angioplasty. In 13 patients with normal coronary angiograms, peak contrast intensity corrected for background myocardial intensity was measured in 36 regions and was found to increase after papaverine from 36 +/- 16 to 55 +/- 22 U (p less than 0.001). In contrast, in the 27 patients with angiographic evidence of coronary artery disease, peak intensity in 64 regions remained unchanged after papaverine (35 +/- 22 versus 36 +/- 23 U). An increase in peak intensity greater than or equal to 10 U was 80% sensitive and 92% specific for coronary artery disease. After successful coronary angioplasty, peak intensity in the involved regions improved significantly (p less than 0.001) during baseline contrast injections (from 32 +/- 16 to 50 +/- 25 U) as well as in the postpapaverine contrast injections (from 30 +/- 12 to 60 +/- 26 U). In conclusion, measurement of peak contrast intensity after intracoronary injections of sonicated meglumine provides a relative index of myocardial perfusion that allows assessment of regional coronary reserve in patients with coronary artery disease. This may be of particular value in evaluating the immediate effects of coronary angioplasty on myocardial perfusion.

Clinical significance of perfusion defects by thallium-201 single photon emission tomography following oral dipyridamole early after coronary angioplasty

The clinical significance of myocardial perfusion defects present early after angiographically successful percutaneous transluminal coronary angioplasty was assessed in 53 patients using thallium-201 single photon emission computed tomography combined with pharmacologic vasodilation induced by a large dose (300 mg) of orally administered dipyridamole. Myocardial tomographic images were obtained at a mean of 20 +/- 6 h (SD) before and 2.9 +/- 2.7 days after angioplasty. Before angioplasty, 15 (28%) of the 53 patients developed angina after dipyridamole administration, in contrast to only 3 (7.5%) of 40 patients after angioplasty (p less than 0.001). The mean percent luminal area stenosis decreased from 93 +/- 6% before angioplasty to 34 +/- 17% after angioplasty (p less than 0.001). Myocardial perfusion defects, present in 49 (93%) of the 53 patients before angioplasty, were reversible in 44 patients (83%), all of whom underwent dilation of arteries supplying the ischemic areas. After angioplasty, 26 (65%) of 40 patients had no ischemic defects, whereas 14 (35%) of the patients still had an ischemic defect in the vascular territory of the dilated artery. After a mean follow-up period of 21.7 months, 13 (33%) of 39 patients developed restenosis, 10 of whom had an ischemic defect early after angioplasty. Restenosis developed in 10 (71%) of 14 patients with an ischemic defect after angioplasty, but in only 3 (11.5%) of the patients without an ischemic defect (p = 0.007). In conclusion, thallium-201 tomography after oral dipyridamole affords convenient assessment of the physiologic significance of coronary stenosis present before angioplasty and the residual stenosis after angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Follow-up results of distal coronary artery bypass for ischemic heart disease

Abstract Statistically significant late results of coronary artery bypass procedures will be unavailable for 5 to 10 years. This report summarizes a critical analysis of the present status of 480 patients followed up for 1 to 30 months after coronary artery bypass. Thirty-day hospital mortality was 6.2 percent and appears to be declining. Arteriographic studies have shown only 1 of 220 patients without at least 1 functioning graft. Graft occlusions appear to be early and technically oriented and ranged from 11 to 14 percent. Significant symptomatic improvement as determined by cardiologists was observed in 92 percent of patients. According to functional classification there was a striking shift from preoperative New York Heart Association classes II, III, and IV, to class I as a result of improved myocardial blood flow. No degenerative changes in autogenous vein bypass grafts have been observed.

Transluminal coronary angioplasty in the elderly

The safety and clinical efficacy of percutaneous transluminal coronary angioplasty (PTCA) in elderly patients has not been established. Of 639 PTCAs performed between March 1980 and May 1984, 119 patients were 65 years or older (mean 70 years). On angiography, elderly patients differed only in the more frequent occurrence of visible calcific deposits (26% vs 8% in younger patients, p less than 0.01). Primary success was achieved in 81%, vs 80% in patients younger than 65 years. Major complication rates were comparable to those of younger patients: emergency coronary artery bypass surgery, 4.1% vs 4.7%; acute myocardial infarction, 2.5% vs 2.9%; and death, 0.8% vs 0. Late clinical follow-up ranging from 5 to 50 months (mean 18) showed that symptomatic improvement was achieved in 91% of patients in whom PTCA was successful, with 55% being asymptomatic. Seventy percent of patients were as active or more active (30%) than before PTCA and 47% were taking fewer medications. Four late deaths occurred, none from cardiac causes. These data support the safety and clinical effectiveness of PTCA in elderly patients and justify the extension of indications for PTCA to selected patients with multivessel disease in this age group.

Intracoronary thrombolytic therapy in acute myocardial infarction: a prospective, randomized, controlled trial.

A prospective, randomized trial was designed to assess the efficacy of intracoronary thrombolytic therapy with streptokinase (STK) in acute myocardial infarction. Sixty-four patients with acute myocardial infarction were randomized within 6 hours of onset of symptoms to 1 of 3 groups. Sixteen patients were treated by conventional means (control group). Nineteen patients underwent coronary arteriography and received corticosteroids and intracoronary and intravenous nitroglycerin (NTG group). Twenty-nine patients received management identical to that of the NTG group, with the addition of intracoronary STK therapy (STK group). Recanalization was demonstrated in 21 of 29 patients (72%) in the STK group. Global and regional ejection fraction (EF) was determined by radionuclide ventriculography before any intervention and 7 to 10 days later. No significant improvement in global EF was achieved in the control and NTG groups. In STK patients as a group, global EF did not increase significantly; however, in patients recanalized with STK, EF improved from 42 +/- 17% to 49 +/- 16% (p = 0.023). All groups showed wide variability of response. Improvement in global EF of more than 5% was noted in 44% of patients recanalized with STK. When subgrouped on the basis of initial global EF of 45% or less or more than 45%, only patients recanalized with STK with an initial EF of 45% or less had an improved global EF (from 30 +/- 10% to 42 +/- 10%, p = 0.015).(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo assessment of vascular dilatation during percutaneous transluminal coronary angioplasty

Previous studies of the mechanism of percutaneous transluminal coronary angioplasty used either postmortem specimens or animal models. To characterize the process of vascular dilatation in vivo, a system was devised for recording the instantaneous pressure-volume changes in the angioplasty balloon during inflation within the stenosed artery. The pressure-volume patterns obtained were compared with those observed in vitro with the balloon inflated in materials whose properties simulate stretching (Silastic tubing), compaction (styrofoam) and cracking (dry macaroni). Of 48 narrowings in 46 patients, a pressure-volume pattern of stretching was observed in 56%, compaction in 27% and cracking in only 17%. Of lesions manifesting a stretching pattern, 85% were longer than 5 mm cr had visible calcium deposits, whereas those that compacted were shorter and lacked calcium deposits. Both of these pressure-volume patterns were associated with a successful clinical outcome. Of 8 lesions exhibiting a cracking pattern, 6 showed dissection angiographically; 3 of these resulted in vessel occlusion.

Effects of transluminal coronary angioplasty on left ventricular systolic and diastolic function at rest and during exercise

The left ventricular global and regional systolic function, ventricular volumes, and peak diastolic filling rate (PDFR) were studied in 30 patients with coronary artery disease, before and 2 to 5 days after transluminal coronary angioplasty (PTCA), utilizing equilibrium radionuclide angiography at rest and during exercise. At rest, the global ejection fraction (EF) was unchanged before (60 +/- 9%) and after PTCA (62 +/- 10%). During exercise, global EF increased from 59 +/- 11% pre PTCA to 67 +/- 10 post PTCA (p less than 0.001). Twenty-two patients had abnormal EF response to exercise pre PTCA, versus seven post PTCA (p less than 0.001). Improvements in exercise regional EF paralleled the changes in global EF. End-systolic volume was unchanged at rest but decreased significantly with exercise post PTCA (60 +/- 36 ml pre vs 49 +/- 32 ml post PTCA, p less than 0.01). At rest, the PDFR was unchanged post PTCA (2.4 +/- 0.9 end-diastolic volume (EDV)/sec pre vs 2.5 +/- 0.8 EDV/sec post). During exercise, PDFR increased from 2.1 +/- 0.7 EDV/sec pre PTCA to 2.5 +/- 0.7 EDV/sec post PTCA (p less than 0.02). In conclusion, in patients with coronary artery disease, successful PTCA improves global and regional systolic function during exercise. Diastolic function is improved during exercise, a fact not previously demonstrated.

Quantitative analysis of thallium-201 uptake and washout before and after transluminal coronary angioplasty

Transluminal coronary angioplasty has become an important therapeutic modality in the treatment of coronary artery disease. The effects of coronary angioplasty on regional myocardial perfusion have been reported in only a small series of patients, employing subjective analysis of thallium-201 perfusion scintigrams. Thus, we studied 61 patients with quantitative analysis of thallium-201 uptake and washout before and after undergoing angioplasty. Prior to angioplasty, there were 105 areas in 47 patients with abnormal thallium-201 uptake during exercise, with a mean uptake of 49 +/- 1.3%. The uptake of thallium-201 in these same areas increased to 71.3 +/- 1.9% post angioplasty (P less than 0.0001), and 68 (65%) of the areas showing abnormal uptake returned to normal. Abnormalities in washout of thallium-201 before angioplasty were seen more frequently than in uptake (150 vs 105 areas, P less than 0.05), with 8 patients having abnormal washout in the presence of totally normal uptake. Thallium-201 washout in the abnormal areas improved from 16 +/- 2.8 pre angioplasty to -23 +/- 1.8% post angioplasty (P less than 0.001). Normalization resulted in 6 of the 8 patients with exclusively washout abnormality. Residual abnormalities in uptake and/or washout were seen in 53% of the patients, usually in areas with prior myocardial infarction or supplied by a vessel with significant stenosis which did not undergo angioplasty. Improved thallium-201 uptake and washout corresponded to reductions in percent coronary area stenosis (89 +/- 1.0 to 36 +/- 2.0%, P less than 0.001) and transstenotic pressure gradient (42 +/- 3.0 to 9.0 +/- 2.0 mm Hg, P less than 0.001). Thus, quantitative analysis of thallium-201 uptake and washout provided objective evidence for improved myocardial perfusion after coronary angioplasty. Due to a fairly high prevalence of residual perfusion abnormalities after this procedure, optimal assessment of benefits requires quantitative comparison of thallium uptake and washout before and after coronary angioplasty.

Factors influencing the outcome of balloon aortic valvuloplasty in the elderly

This study describes the short- and long-term outcome of 44 consecutive percutaneous balloon aortic valvuloplasty procedures performed in 42 elderly patients (age 77.8 +/- 7 years) with calcific aortic stenosis. The initial success rate was 95%, with the peak aortic valve pressure gradient declining from a mean of 82 +/- 32 mm Hg to 44 +/- 23 mm Hg and aortic valve area increasing from a mean of 0.59 +/- 0.15 cm2 to 0.83 +/- 0.40 cm2. One procedure-related death occurred and an additional three patients died less than or equal to 30 days after balloon aortic valvuloplasty. These patients all had New York Heart Association (NYHA) class IV heart failure symptoms prior to the procedure and their mean left ventricular ejection fraction (LVEF) (28 +/- 7%) was lower than that of hospital survivors (52 +/- 13%) (as was their ratio of left ventricular [LV] wall thickness-to-cavity ratio [0.50 +/- 0.10 versus 0.70 +/- 0.15]). At the time of hospital discharge after valvuloplasty, 76% of patients were asymptomatic or markedly improved (NYHA class I or II). After a mean follow-up of 15.5 months (range 2 to 26 months), however, 10 patients had died and 15 had undergone aortic valve replacement for recurrence of NYHA class III or IV symptoms. The adjusted 1- and 2-year survivals were 0.68 and 0.62, respectively, and adjusted 2-year event-free survival was 0.25. Proportional hazard regression analysis indicated that LVEF less than 40% was the only variable affecting survival (p less than 0.01) and was a possible indicator of event-free survival (p = 0.07).(ABSTRACT TRUNCATED AT 250 WORDS)