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W K Laskey

Publications and source records attributed to W K Laskey.

At least 37 records · Page 2Linked to original sources
PubMed1997

Ischemic preconditioning in unstable coronary syndromes: evidence for time dependence.

OBJECTIVES: We hypothesized a time-dependent relation between angina occurring spontaneously before percutaneous transluminal coronary angioplasty (PTCA) and the likelihood of an ischemic response during initial balloon occlusion. We further hypothesized that the ability to elicit the "classic" mode of PTCA-related preconditioning would vary with the interval from clinical angina to PTCA. BACKGROUND: Antecedent angina represents a potential for myocardial preconditioning in unstable ischemic coronary syndromes. METHODS: We studied 67 patients with Braunwald class III unstable coronary syndromes undergoing PTCA. The interval between the last spontaneous episode of angina preceding PTCA and initial balloon inflation was categorized as follows: 0 to 6 h; 6 to 12 h; 12 to 24 h; and >24 h. RESULTS: Across the various intervals, there was a significant difference (p = 0.004) in the proportion of patients with an absent ischemic response during the first balloon inflation (0 to 6 h, 50%; 6 to 12 h, 35%; 12 to 24 h, 23%; and >24 h, 4%). There was, however, no difference between the first and second inflations in the proportion of patients with a diminished ischemic response until 6 to 12 h (p = 0.017) had elapsed since the last spontaneous episode of angina. Patients whose angina last occurred >24 h before the first inflation showed the greatest inducibility of PTCA-related preconditioning. CONCLUSIONS: Strong evidence exists for the occurrence of ischemic preconditioning in unstable coronary syndromes. Although the protective effect of spontaneous angina appears to wane beyond 6 h, recovery of preconditioning occurs from 6 to 12 h. Thus, preconditioning can be reinduced during PTCA with a marked potentiation of the effect at 24 h. This suggests an underlying time-dependent mechanism with a physiologic "half-life" of 6 to 12 h.

Angina, Unstable↗
PubMed1997

Utility of magnetic resonance imaging in a patient with anomalous origin of the right coronary artery, acute myocardial infarction, and near-sudden cardiac death.

A 46-year-old female presented with an acute myocardial infarction and cardiac arrest. Coronary angiography revealed an anomalous origin of the right coronary artery coursing between the aorta and pulmonary artery. Magnetic resonance imaging confirmed the life-threatening nature of this anomaly and led to referral for surgical revascularization.

Coronary Angiography↗
PubMed1997

Risk of major complications from coronary angioplasty performed immediately after diagnostic coronary angiography: results from the Registry of the Society for Cardiac Angiography and Interventions.

OBJECTIVES: This study was designed to determine the risk of performing percutaneous transluminal coronary angioplasty (PTCA) at the time of diagnostic catheterization ("combined procedures"). BACKGROUND: Health care providers are under increasing pressure to combine diagnostic and interventional coronary procedures to reduce costs. However, the risk associated with combined procedures has not been rigorously assessed. METHODS: A multicenter cohort study of 35,700 patients undergoing elective PTCA from 1992 through 1995 was performed to determine the risk of major complications (myocardial infarction, emergency coronary artery bypass graft surgery or death) from combined relative to staged procedures (i.e., performing PTCA at a session subsequent to diagnostic catheterization). RESULTS: The risks of major complications from combined and staged procedures were 2.0% and 1.6%, respectively (unadjusted odds ratio [OR] 1.28, 95% confidence interval [CI] 1.05 to 1.57). After adjusting for clinical and angiographic differences and clustering by laboratory, the risk from combined procedures was not significantly elevated (multivariable OR 1.18, 95% CI 0.89 to 1.55). However, several subgroups of patients did have an increased risk from combined procedures: patients with multivessel disease (multivariable OR 1.64, 95% CI 1.13 to 2.39); women (multivariable OR 1.64, 95% CI 1.05 to 2.55); patients > 65 years old (multivariable OR 1.40, 5% CI 1.02 to 1.93); and patients undergoing multilesion PTCA (multivariable OR 1.53, 95% CI 1.06 to 2.21). The risk of combined relative to staged procedures decreased over the 4-year period (multivariable p = 0.029). CONCLUSIONS: Combining PTCA with diagnostic catheterization appears to be safe in many patients. However, several subgroups of patients may be at increased risk. Careful patient selection will most likely remain critical to ensuring the safety of combined procedures.

Aged↗
PubMed1996

Left ventricular diastolic response to exercise in valvular aortic stenosis.

Exercise produces profound alterations in symptoms and hemodynamics in patients with valvular aortic stenosis (AS). Prior studies have demonstrated marked increases in late left ventricular (LV) diastolic filling pressure with exercise. Little information is available on the exercise response of indexes of early LV diastolic performance. Catheter-tip manometer recordings in 11 patients with AS and 5 age-matched controls were obtained at rest and with supine bicycle exercise at the time of cardiac catheterization. Pressure-derived indexes of LV diastolic performance, isovolumic relaxation rate, and diastolic interval data were examined. At rest, early (patients 22 +/- 6 mm Hg, controls 12 +/- 3 mm Hg; p < 0.01), minimal (patients 9 +/- 4 mm Hg, controls 4 +/- 1 mm Hg; p < 0.01), and late (patients 28 +/- 10 mm Hg, controls 13 +/- 3 mm Hg; p < 0.002) LV diastolic pressures were elevated in patients with AS. The time to onset of isovolumic relaxation (patients 422 +/- 31 ms, controls 363 +/- 40 ms; p < 0.01) and minimal LV diastolic pressure (patients 608 +/- 57 ms, controls 448 +/- 52 ms; p < 0.002) at rest were prolonged in patients with AS. With exercise, early (patients 45 +/- 14 mm Hg, controls 15 +/- 3 mm Hg; p < 0.002), minimal (patients 15 +/- 6 mm Hg, controls 2 +/- 1 mm Hg; p < 0.01), and late (patients 38 +/- 10 mm Hg, controls 18 +/- 5 mm Hg; p < 0.002) LV diastolic pressures were elevated, and the time to minimal LV diastolic pressure (patients 528 +/- 26 ms; controls 393 +/- 56 ms) and peak first derivative of LV pressure decline (-LV dP/dt) patients 395 +/- 41 ms, controls 326 +/- 59 ms) were prolonged in AS. Furthermore, patients with AS failed to comparably increase the rate of LV pressure decay and isovolumic relaxation with exercise. The LV diastolic response to exercise in patients with AS is distinguished from the control response by suboptimal and prolonged relaxation and a diminished rate of LV pressure decay. These abnormal responses in early diastolic function coupled with the known abnormal chamber distensibility in AS contribute to significant elevations in early, mid-, and late diastolic pressures with exercise.

Adult↗
PubMed1995

The relationship between coronary angioplasty procedure volume and major complications.

OBJECTIVE: To assess the relationship between the volume of percutaneous transluminal coronary angioplasty (PTCA) procedures performed in a cardiac catheterization laboratory and major complications after adjusting for case mix and to evaluate the applicability of current guidelines for minimum laboratory volume. DESIGN: Cohort study using the 1992 and 1993 registries of the Society for Cardiac Angiography and Interventions. SETTING: Forty-eight cardiac catheterization laboratories from throughout the United States and Canada. PATIENTS: All 19 594 consecutive patients without an acute myocardial infarction (MI) undergoing a first coronary balloon angioplasty. MAIN OUTCOME MEASURES: Emergency bypass surgery, MI, or in-hospital death. RESULTS: There was a significant decrease in the rates of in-hospital mortality (P = .04), emergency bypass surgery (P < .001), MI (P - .001), and major complications (defined as one or more of these outcomes; P < .001) with increasing cardiac catheterization laboratory volume. After adjustment for case mix using multivariable analysis, these associations persisted, although the association with mortality was no longer statistically significant. There was no significant difference in outcomes in laboratories performing at least 200 vs fewer than 200 procedures per year, the currently recommended minimum laboratory volume (odds ratio [OR] for major complications, 0.81; 95% confidence interval [CI], 0.53 to 1.25). However, a statistically significant decrease in major complications was observed in laboratories performing more than 400 procedures per year (adjusted OR, 0.66; 95% CI, 0.46 to 0.96; P = .03; and OR, 0.54; 95% CI, 0.38 to 0.78; P = .001) when laboratories performing 400 through 599 procedures and at least 600 procedures per year, respectively, are compared with those performing fewer than 200 per year. CONCLUSIONS: An inverse association between cardiac catheterization laboratory procedure volume and major complications during PTCA exists independent of differences in patients' risk profiles. Our data suggest that the currently recommended minimum laboratory volume may be too low to distinguish higher-risk from lower-risk laboratories.

Aged↗
PubMed1995

Valvular and systemic arterial hemodynamics in aortic valve stenosis. A model-based approach.

BACKGROUND: Assessment of the severity of a stenotic aortic valve has been confounded by reports of flow dependence of stenosis severity. We hypothesized that the pressure gradient at the stenotic aortic valve would be dependent on the characteristics of the arterial circulation. Therefore, clinically useful measures of the severity of aortic valve stenosis may have to take this dependence into account. METHODS AND RESULTS: We developed an analog model of the systemic arterial circulation in the presence of a stenotic aortic valve. The model clearly describes the dependence of stenosis severity (described by coefficients A and B) on the resistive and capacitive properties of the arterial system. We used high-fidelity pressure recordings obtained at the time of diagnostic cardiac catheterizations and found that a highly significant relation between the measured mean transvalvular gradient and that predicted by the model was demonstrated both at rest (r2 = .90) and with exercise (r2 = .80). Furthermore, the relative constancy of stenosis coefficients A and B was validated. CONCLUSIONS: Transvalvular hemodynamics in patients with aortic valve stenosis are dependent on the properties of the arterial system. The current model describes such behavior, correctly predicts the transvalvular gradient from model parameters, and may be useful in the assessment of stenosis severity under various clinical and physiological conditions.

Aged↗
PubMed1995

Development and validation of simplified predictive index for major complications in contemporary percutaneous transluminal coronary angioplasty practice. The Registry Committee of the Society for Cardiac Angiography and Interventions.

OBJECTIVES: This study was designed to determine the preprocedural risk factors for major complications (emergent coronary bypass surgery, myocardial infarction or death) of coronary angioplasty and to derive and validate a simplified index that predicts patients' a priori risk of complications. BACKGROUND: Previous studies of risk factors for complications after coronary angioplasty may not be generalizable to current, broad-based angioplasty practice. Furthermore, to our knowledge a clinically useful predictive index has not been derived and independently validated. METHODS: From data collected prospectively for the Registry of the Society for Cardiac Angiography and Interventions for 1992, multivariable logistic regression was used to determine which variables were independently associated with complications in 10,622 first angioplasty procedures. Stepwise regression and receiver operating characteristic curves then were used in this registry to develop a predictive index for complications that was validated using 5,250 first angioplasty procedures in the 1993 registry. RESULTS: Predictors of major complications were multivessel disease, unstable angina, recent myocardial infarction, type C lesion or left main angioplasty, shock, age, geographic region and absence of previous coronary bypass surgery. The derived predictive index consisted of the first six of these variables plus aortic valve disease and classified patients into four risk groups: low (1.3% complications), moderate (2.8%), high (12.7%) and very high (29.7%) risk. This index demonstrated consistent reliability and discriminatory ability when applied to the 1993 data. CONCLUSIONS: Predictors of major complications identified in selected populations also apply currently in broad-based practice. From these variables, a predictive index can stratify patients into risk groups before angioplasty, thus aiding in risk assessment, resource allocation and risk adjustment.

Angioplasty, Balloon, Coronary↗
PubMed1994

Efficacy of adjunctive thrombolytic therapy in percutaneous transluminal coronary angioplasty.

Adjunctive thrombolysis has not been shown to improve angioplasty success or complication rates in elective angioplasty or myocardial infarction and may be detrimental in unstable angina. Thrombolysis of chronically occluded vessels achieves recanalization at a rate comparable to conventional angioplasty and is associated with a high rate of complications and limited long-term patency. Thrombolysis administered for thrombus or acute occlusion complicating angioplasty usually achieves coronary artery patency but is unable to forestall complications in many cases. A benefit of thrombolysis in reducing restenosis has not been conclusively demonstrated.

Angioplasty, Balloon, Coronary↗
PubMed1994

Ischemia-induced changes in human endocardial electrograms during percutaneous transluminal coronary angioplasty.

The electrophysiologic sequelae of acute reversible transmural myocardial ischemia in humans are poorly understood. Experimental models have demonstrated slowing of conduction in ischemic myocardium, but similar evidence in humans is lacking. We used percutaneous transluminal coronary angioplasty as a model for reversible ischemia to (1) analyze the regional endocardial electrogram response to ischemia and (2) determine whether an initial episode of ischemia may mitigate the effects of a subsequent bout of ischemia (preconditioning). We recorded bipolar left ventricular endocardial electrograms during elective angioplasty in 11 patients and examined changes in amplitude and duration on the electrogram. Each of the 11 patients underwent two to seven balloon inflations. The electrogram amplitude at 90 seconds of balloon occlusion fell to 86% +/- 17% of the control value, and the electrogram duration increased to 109% +/- 12% of the control value. These variables returned to baseline values by 30 and 120 seconds, respectively, after balloon deflation. Among the six patients in the preconditioning protocol, the electrogram duration at 90 seconds was less with the second inflation (106% +/- 7%) than with the first (115% +/- 17%, p < 0.05). The difference in electrogram amplitude between the first and the second inflation was not significant (88% +/- 17% vs 85% +/- 13%, p = NS). At 60 seconds of ischemia there was no difference between normal sinus rhythm and paced complexes in the magnitude of change in electrogram amplitude or duration. We conclude that acute transmural myocardial ischemia in humans is associated with a decrease in local bipolar endocardial electrogram amplitude and an increase in electrogram duration. These findings are consistent with slowed conduction in the ischemic zone and are in agreement with experimental findings in animals. Furthermore, a preconditioning effect on electrogram duration suggests a possible protective effect for repeated bouts of ischemia.

Acute Disease↗
PubMed1994

Pressure recovery in aortic valve stenosis.

BACKGROUND: Pressure recovery is the variable increase in lateral pressure downstream from a stenotic orifice. The magnitude and clinical significance of pressure recovery in aortic valve stenosis are poorly defined. METHODS AND RESULTS: We obtained high-fidelity pressure and velocity recordings in 11 patients with isolated significant aortic valve stenosis at the time of diagnostic cardiac catheterization. Systematic catheter pullback from the left ventricular cavity revealed a consistent although variable subvalvular gradient. Further pullback across and distal to the region of the stenosed aortic valve revealed a consistent and progressive increase in the ascending aortic pressure. This increase in lateral pressure occurred pari passu with a diminution in amplitude of the velocity pulse. The extent of pressure recovery was directly related to systemic blood flow and transvalvular flow but inversely related to the Gorlin-derived aortic valve area. CONCLUSIONS: These findings have potentially important implications for the hemodynamic evaluation of mild to moderately severe aortic valve stenosis. The extent of pressure recovery may be of additional utility in the assessment of aortic valve stenosis under varying physiological states.

Aorta↗