Coronary vasomotor tone: determinants and effect on coronary angioplasty.

BACKGROUND: Coronary artery reference diameters increase during coronary angioplasty (PTCA). However, in clinical practice, balloon selection is often based on a preceding diagnostic coronary angiogram. It is common to find that the initially selected balloon is undersized due to resting vasomotor tone. This may contribute to a suboptimal angioplasty result. METHODS: Quantitative coronary angiography (QCA) was used to determine the magnitude of coronary artery vasodilatation over baseline angiography and its impact on balloon size choice. Pre-PTCA clinical and treatment variables were analyzed for their potential contribution to resting vasomotor tone. RESULTS: QCA of reference coronary diameters was performed in a group of 103 patients undergoing PTCA. Post PTCA proximal and distal reference diameters significantly increased over baseline. The average increase of the proximal segment was 0.368 mm (13.6%) p < 0. 001 and of the distal segment 0.567 mm (24.8%) p < 0.001. The initial nominal balloon diameter was smaller than the post PTCA proximal segment by an average of 0.34 mm (12.6%) p < 0.001. Of the clinical and treatment variables examined age < 65 years and pre-PTCA beta blocker use, significantly affected baseline vasomotor tone p < 0.05. CONCLUSIONS: Routine diagnostic angiography underestimates the true diameter of the coronary artery. Due to baseline vasomotor tone, coronary reference segments can be expected to increase approximately 13% in diameter during successful PTCA. Patients under 65 years of age and those using beta-blockers may have a significantly increased baseline vasomotor tone. Underestimation of coronary artery diameter based on initial angiography necessitated a second, larger balloon in 16.5% of cases.

Lipoprotein(a) level does not predict restenosis after percutaneous transluminal coronary angioplasty.

The serum lipoprotein(a) [Lp(a)] level is a known risk factor for arteriosclerotic coronary artery disease. However, its association with restenosis after percutaneous transluminal coronary angioplasty (PTCA) is controversial. We hypothesized that the Lp(a) level is a significant risk factor for restenosis after angioplasty through a pathophysiological mechanism leading to excess thrombin generation or inhibition of fibrinolysis. We designed a prospective study of the relation of Lp(a) to outcome after PTCA, in which we measured selected laboratory variables at entry and collected clinical, procedural, lesion-related, and outcome data pertaining to restenosis. Restenosis was defined as >50% stenosis of the target lesion by angiography or as ischemia in the target vessel distribution by radionuclide-perfusion scan. Before the patients underwent PTCA, blood was obtained by venipuncture for measurement of Lp(a), total cholesterol, thrombin-antithrombin (TAT) complex, alpha2-antiplasmin-plasmin (APP) complex, and plasminogen activator inhibitor-1 (PAI-1). Evaluable outcome data were obtained on 162 subjects, who form the basis of this report. Restenosis occurred in 61 subjects (38%). The Lp(a) level was not correlated significantly with TAT, APP, PAI-1, or the TAT-APP ratio. Levels of TAT, APP, and PAI-1 were not statistically different in the patients with versus those without restenosis. The median ratio of TAT to APP was 2-fold higher in the restenosis group, and this difference approached statistical significance (P=0.07). Univariate analysis was performed for the association of clinical, lesion-related, and procedural risk factors with restenosis. Lp(a) levels did not differ significantly in the restenosis versus no-restenosis group, whether assessed categorically (>25 mg/dL versus <25 mg/dL) or as a continuous variable by Mann-Whitney U test. The number of lesions dilated and the lack of family history of premature heart disease were significantly associated with restenosis (P=0.002 and P=0.008, respectively). A history of diabetes mellitus was of borderline significance (P=0.055). By multiple logistic regression analysis, the number of lesions dilated was the only variable significantly associated with restenosis (P=0.03). We conclude that the number of lesions dilated during PTCA is a significant risk factor for restenosis, whereas the serum Lp(a) level was not a significant risk factor for restenosis in our patient population. The TAT to APP ratio merits further study as a possible risk factor for restenosis.

Enhanced external counterpulsation as an adjunct to revascularization in unstable angina.

Enhanced external counterpulsation (EECP) is an effective noninvasive treatment for chronic stable angina. Despite intensive risk factor modification, a patient required two surgical coronary revascularizations and seven multivessel angioplasties over a 26-month period, demonstrating recurrent unstable angina and persistent thallium perfusion defects despite revascularization. Post EECP, angina was relieved, thallium defects were resolved and the patient has remained asymptomatic for 36 months.

Acute myocardial infarction with dynamic outflow obstruction precipitated by intra-aortic balloon counterpulsation.

Dynamic left ventricular outflow obstruction is associated with structural findings of asymmetric septal hypertrophy (less commonly concentric left ventricular hypertrophy) and systolic anterior motion of the anterior mitral valve leaflet. A patient who did not have this usual substrate for outflow obstruction presented with an acute anterior wall myocardial infarction complicated by congestive heart failure and cardiogenic shock. When an intra-aortic balloon pump was placed, the patient rapidly deteriorated and a dynamic outflow gradient was detected.

Transmural myocardial infarction with coexisting critical aortic stenosis as an etiology for early myocardial rupture.

Myocardial rupture is the most important cause of post-infarct sudden death after myocardial infarction other than shock and dysrhythmias. Usually unrecognized, pseudoaneurysm formation is a delayed consequence of myocardial rupture in a small portion of patients who will remain at high risk for late rupture and death. Clinical studies have defined a profile of the patient who is at increased risk for post-infarct myocardial rupture. We believe that an additional factor, ventricular outflow tract obstruction, may add to the risk of having a post infarct rupture. A high degree of suspicion by the clinician accompanied by the timely performance of diagnostic tests may help to decrease the mortality from this catastrophic event.

The effects of chronic oral milrinone therapy on early postinfarction left ventricular remodeling.

Left ventricular remodeling following acute transmural myocardial infarction may result in early left ventricular enlargement. To characterize the effects of milrinone on components of early left ventricular dilation, rats (n = 120) underwent left coronary artery ligation or sham surgery. In the immediate postoperative period, rats received either no treatment or milrinone (3.17 +/- 0.08 mg/kg/day) dissolved in drinking water for 20 days. Twenty-one days after the initial surgery, hemodynamic measurements were made. The rats were then put to death and the hearts arrested in diastole were excised and fixed at a constant pressure for morphometric analysis. To examine the effects of milrinone on the relative contribution of infarcted and noninfarcted segments to early left ventricular dilation after acute myocardial infarction, a subgroup of infarcted rats chosen randomly was put to death 3 days after the initial surgery for morphometric analysis. Compared with infarcted untreated rats, infarcted milrinone-treated rats had a lower left ventricular volume (1.41 +/- 0.07 ml/kg vs 2.16 +/- 0.19 ml/kg, p < 0.001), lower left ventricular wall stress (0.64 +/- 0.03 vs 0.91 +/- 0.06, p < 0.001), and a lower expansion index (1.61 +/- 0.12 vs 2.61 +/- 0.22, p < 0.001). Morphometric analysis revealed that the noninfarcted segment length did not differ between the two infarcted groups either 3 days or 21 days after left coronary artery ligation. Infarct segment length also did not differ between the two infarcted groups at 3 days, but at 21 days infarct segment was shorter in the milrinone-treated group compared with the untreated group (p < 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Fatty infiltration: another restrictive cardiomyopathic pattern.

Restrictive cardiomyopathies have been shown to occur as result of infiltrative processes from a variety of sources. The current report describes an obese male, who was found to have hemodynamic evidence of a restrictive cardiac process. His pericardium was proven to be normal and an incisional biopsy obtained of the myocardium during coronary artery bypass surgery demonstrated histologic evidence of fatty infiltration of myocardium. Review of the restrictive and pathology literature is discussed and indicates that this is the first report to demonstrate the association between fatty infiltration and hemodynamic findings consistent with a restrictive cardiomyopathy.

Emergency coronary revascularization using polytetrafluoroethylene conduits in a patient in cardiogenic shock.

There is growing awareness that a particular subset of patients with coronary artery disease who need surgical revascularization do not have autologous vein or internal mammary artery available or surgically applicable. The polytetrafluoroethylene graft has had limited use in aortocoronary bypass procedures. We describe a case of cardiogenic shock secondary to severe coronary artery disease and aortic stenosis, where the use of this synthetic graft contributed to a successful outcome. Angiographic patency was documented at 3 months follow-up. Our experience, plus a review of the literature, supports the use of polytetrafluoroethylene grafts during aortocoronary artery bypass to salvage infarcting or ischemic myocardium, when traditional autologous bypass conduits are not available or applicable.

Myocardial revascularization with the lateral costal artery.

The lateral costal artery is a branch of the internal mammary artery that occurs in 27% of cadaver series. The similarities to the internal mammary artery and its easy accessibility would suggest its use as a bypass conduit for coronary revascularization. We describe the harvesting and utilization of this artery as an in situ coronary bypass graft, and we have initiated a study examining the exact frequency of this anomalous vessel. The availability of the lateral costal artery either unilaterally or bilaterally adds another dimension to the concept of complete arterial conduit myocardial revascularization.

Recurrent ischemia in the zone of prior myocardial infarction: results of coronary angioplasty of the infarct-related artery.

We studied the efficacy of coronary angioplasty (PTCA) of the infarct-related artery in 54 patients with recurrent myocardial ischemia in the zone of prior infarction. Our patients had recurrent ischemia 10 +/- 7 days after infarction, with 75% experiencing rest angina and 15% having evidence of reinfarction. Angiography of the infarct-related artery demonstrated a critical stenosis in 35 of 54, a subtotal occlusion in 5 of 54, and a total occlusion in 14 of 54. PTCA was successful in 94% of critical stenoses, 80% of subtotal occlusions, but in only 50% of total occlusions. Complications related to PTCA included a 3.7% rate of emergency surgery, but no deaths or infarctions. During the clinical follow-up period of 11 +/- 7 months, there was one reinfarction and no deaths. Although 27% of our 44 patients with a successful initial PTCA required a second revascularization procedure for recurrent angina, 40 patients (91%) remained symptomatically improved with angioplasty alone (including successful repeat PTCA in eight patients). We conclude that PTCA of the infarct-related artery is beneficial for selected patients with recurrent ischemia in the zone of prior infarction.

Percutaneous transluminal coronary angioplasty in patients with prior myocardial infarction: angioplasty at a distance from the prior infarct zone.

Patients undergoing coronary angioplasty who have had a prior transmural myocardial infarction in the distribution of a contralateral coronary artery are considered a high-risk group because of potentially severe left ventricular dysfunction if an ischemic complication occurs. The purpose of this study was to evaluate the safety and efficacy of coronary angioplasty in 28 patients with prior myocardial infarction remote from the artery undergoing dilatation. Prior myocardial infarction was defined by the presence of pathologic Q waves on ECG or segmental akinesis on ventriculography. Angioplasty was successful in 30 of 33 lesions (91%) and in 25 of 28 patients (89%). Mean stenosis diameter was reduced from 91% +/- 7% to 28% +/- 16%; mean translesional gradient after angioplasty was 6 +/- 5 mm Hg. No patient developed severe hemodynamic deterioration from transient coronary occlusion during balloon inflation or from an acute ischemic complication. Three patients underwent coronary artery bypass surgery after unsuccessful angioplasty. There were no new Q wave infarctions or deaths. The results of coronary angioplasty in patients with prior infarction were compared with those of 203 patients without prior remote infarction. Primary success and occurrence of major complications were comparable in both groups. At a mean follow-up of 12 +/- 6 months, 18 of the 25 patients (72%) who underwent initially successful dilatation have remained symptom free with angioplasty alone. Therefore, coronary angioplasty is a suitable therapeutic procedure in carefully selected patients with angina pectoris and prior myocardial infarction at a distance from the site of angioplasty.

Assessment of the relationship between distal occluded pressure and angiographically evident collateral flow during coronary angioplasty.

The relationship between the presence of collateral filling on the baseline coronary angiogram and the distal occluded pressure obtained during balloon inflation was examined in 83 patients undergoing coronary angioplasty. The patients were divided into three groups: Group I (n = 40) had conventional stenoses (80% to 95% luminal diameter narrowing) without angiographically evident collaterals, group II (n = 22) had conventional stenoses with angiographically present collaterals, and group III (n = 21) had total or functional total occlusions (99% to 100% diameter narrowing) with angiographically evident collateral flow. There was no significant difference in age, sex, vessel distribution, clinical class, residual gradient, or residual percent stenosis following successful angioplasty among the three groups. The distal occluded pressure in group I (18 +/- 5 mm Hg) was, however, significantly lower than the distal occluded pressure in either group II (34 +/- 7 mm Hg) or group III (36 +/- 9 mm Hg) (p less than 0.001). This could not be explained by differences in aortic pressure, since there was no correlation between the mean aortic blood pressure and the distal occluded pressure and since the distal occluded pressure/aortic pressure ratio in group I (0.23 +/- 0.07) was significantly lower than that of group II (0.41 +/- 0.09) or group III (0.41 +/- 0.11) (p less than 0.001). These findings indicate a close correlation between the presence of angiographically evident collateral flow and the distal coronary artery pressure during an angioplasty balloon inflation.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial protection during transient coronary artery occlusion in man: beneficial effects of regional beta-adrenergic blockade.

The goal of this study was to verify whether myocardial protection could be achieved via the intracoronary administration of propranolol in patients undergoing percutaneous transluminal coronary angioplasty (PTCA). Accordingly, 21 patients undergoing PTCA were randomly assigned to receive either intracoronary placebo (group A, n = 10) or intracoronary propranolol (group B, n = 11). Three balloon inflations (i.e., coronary artery occlusions) were performed in each patient. Inflations I and II (maximum duration 60 sec) served as control occlusions. Inflation III (maximum duration 120 sec) was performed either after intracoronary administration of saline (2 ml) or propranolol (1.1 +/- 0.2 mg). The following electrocardiographic index of myocardial ischemic injury were measured: (1) time to development of ST segment elevation equal to 0.1 mV and (2) magnitude of ST segment elevation after 60 sec of coronary artery occlusion. Both indexes did not differ significantly between the groups during inflations I and II. In group A the time to development of ST segment elevation of 0.1 mV remained unchanged between the second and third occlusions (25 +/- 5 and 26 +/- 4 sec during inflations II and III, respectively). In group B subselective injection of propranolol into the affected coronary artery significantly prolonged the time to ST segment elevation of 0.1 mV from 19 +/- 4 sec (inflation II) to 53 +/- 9 sec (inflation III; p less than .001). Administration of placebo did not change the magnitude of ST segment elevation 60 sec after coronary artery occlusion between the second and third occlusion in group A (0.16 +/- 0.02 and 0.18 +/- 0.03 mV, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Improved stability and visualization during coronary artery angioplasty using a double catheter technique.

Guiding catheters used in coronary angioplasty can make coronary angioplasty potentially hazardous when they become positionally unstable, induce myocardial ischemia, or impair angiographic visualization. In order to avoid this problem, a double catheter technique was employed in seven patients involving nine procedures consisting of a standard 8 or 9 French angioplasty guiding catheter and a standard 7 French angiographic catheter to prevent coronary flow reduction and to permit improved coronary artery visualization. In two of the procedures, the second diagnostic catheter also permitted the prevention of potential plaque disruption by the guide catheter in the proximal right coronary artery. The predilatation stenosis was 88 +/- 12%; the postdilatation stenosis was 28 +/- 9%. The use of the diagnostic catheter as a second catheter prevented damping and permitted the stable disengagement of the guiding catheter from the coronary artery. This technique is most useful in patients who have proximal right coronary artery stenoses because it provides optimal visualization of the segment undergoing dilatation, avoids the potential for ischemia in more distal stenoses, and thereby allows the procedure to be performed in a controlled, unhurried manner.

Unstable angina and evolving myocardial infarction following coronary bypass surgery: pathogenesis and treatment with interventional catheterization.

Effective therapy for patients with unstable angina or evolving myocardial infarction following coronary bypass surgery requires accurate delineation of the pathoanatomy and prompt intervention. We therefore performed cardiac catheterization in 10 consecutive patients: four with acute myocardial infarction and six with refractory unstable angina (NYHA class IV). All patients with acute myocardial infarction were found to have completely thrombosed vein grafts supplying totally occluded native coronary arteries. In three patients with evolving myocardial infarction occurring within 4 weeks of coronary bypass surgery, graft thrombosis was caused by venous valves in two patients and a suboptimal anastomosis in a third. The fourth patient sustained a myocardial infarction 7 years after coronary bypass surgery with atherosclerotic plaque rupture causing vein graft thrombosis. Therapy with intragraft streptokinase resulted in complete clearing of thrombus, pain relief, and control of injury current in all four patients. Rest angina with concomitant ST and T wave changes occurred in six patients. In two patients symptoms occurred early (within 6 months), whereas angina developed 4 to 10 years after coronary bypass graft surgery in four patients. In the two patients with early recurrence of symptoms suboptimal anastomosis was found in one, while the other patient had a venous valve in the vein graft in conjunction with a stenosis in the native coronary artery. In three of four patients with late recurrence of angina, symptoms developed as a result of atherosclerotic stenosis in their vein grafts; in the fourth patient an occluded graft was found to supply a stenosed native coronary artery.(ABSTRACT TRUNCATED AT 250 WORDS)

The use of an exchange guide wire in coronary angioplasty.

Of 84 consecutive patients referred for coronary angioplasty, an exchange length (260 cm) guide wire was used in 17 (20%) to allow serial passage of different sized dilatation catheters. Exchanges were performed for the following reasons: 1) inability to cross the stenotic segment with a full-sized dilatation catheter, with exchange for a smaller catheter to permit initial dilatation followed by a second exchange to reintroduce the full-sized balloon catheter; 2) premeditated initial use of a low-profile balloon catheter in severe stenosis, with subsequent exchange to a full-sized balloon catheter; 3) inability to achieve a satisfactory reduction of the transstenotic gradient or angiographic stenosis with the initial dilation catheter, requiring subsequent passage of a larger balloon catheter into the partially dilated segment. Eighteen of 19 attempted exchanges and 18 of 19 angioplasty procedures were completed successfully. The use of exchange guide wires permits multiple recrossings of a dilated segment, allows safe serial passage of different sized balloon catheters, and obviates the need for renegotiating difficult proximal coronary anatomy. The exchange guide wire techique can be applied safely and effectively to coronary angioplasty and provides an additional option in the successful completion of movable guide wire angioplasty procedures.