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Biomedical subjects

R Kornowski

Publications and source records attributed to R Kornowski.

At least 55 records · Page 3Linked to original sources
PubMed1999

Preintervention arterial remodeling as an independent predictor of target-lesion revascularization after nonstent coronary intervention: an analysis of 777 lesions with intravascular ultrasound imaging.

BACKGROUND: Pathological and intravascular ultrasound (IVUS) studies have documented arterial remodeling during atherogenesis. However, the impact of this remodeling process on the long-term outcome after percutaneous intervention is unknown. METHODS AND RESULTS: We used preintervention IVUS to define positive and negative/intermediate remodeling in a total of 777 lesions in 715 patients treated with nonstent techniques. Positive remodeling (lesion external elastic membrane area greater than average reference) was present in 313 lesions; intermediate/negative remodeling (lesion external elastic membrane area less than or equal to reference) was present in the other 464. Baseline clinical and angiographic characteristics were similar, except for a slightly higher percentage of insulin-dependent diabetic patients (10.2% versus 6.1%; P=0.054) in the negative/intermediate-remodeling group. Angiographic success and in-hospital and short-term complications were comparable in the 2 groups. There was no significant correlation between remodeling (as a continuous variable) and final lumen area (r=0.06) or final lesion plaque burden (r=0.17). At 18+/-13 months of clinical follow-up, both groups had similar rates of death and Q-wave myocardial infarction: 3.4% and 2.5% for the negative/intermediate-remodeling group versus 2.7% and 2.7% for the positive-remodeling group. However, the target-lesion revascularization (TLR) rate was 20.2% for the negative/intermediate-remodeling group versus 31.2% for the positive-remodeling group (P=0.007), and remodeling, as a continuous variable, was strongly correlated with probability of TLR (P=0.0001). By multivariable logistic regression analysis, diabetes (OR=2.3), left anterior descending artery location (OR=1.8), and remodeling (OR=5.9) were independent predictors of TLR. CONCLUSIONS: Positive lesion-site remodeling is associated with a higher long-term TLR after a nonstent interventional procedure. Thus, long-term clinical outcome appears to be determined in part by preintervention lesion characteristics.

Aged↗
PubMed1999

Percutaneous transmyocardial laser revascularization: an overview.

Transmyocardial revascularization (TMR) is a novel strategy designed to improve anginal symptoms and enhance myocardial perfusion by applying laser energy directly into the ischemic myocardium. Preliminary surgical experiences using TMR have indicated a significant reduction in angina severity, improved quality of life, and some evidence of improved myocardial perfusion in refractory coronary ischemic syndromes. Possible mechanisms to explain the clinical benefit include stimulated angiogenesis, local myocardial denervation, or both. The goal of catheter-based TMR is to create nontransmural endomyocardial channels smaller in size but comparable in tissue effect to the surgical TMR procedure. At present, most percutaneous TMR experiences seem very promising, although derived from nonrandomized registries with a relatively small number of patients. More rigorous assessments of objective and subjective endpoints derived from ongoing larger randomized clinical trials are needed to render definitive conclusion about the validity of this therapeutic strategy in patients with refractory coronary ischemic syndromes. Cathet. Cardiovasc. Intervent. 47:354-359, 1999.

Angina Pectoris↗
PubMed1999

Evaluation of the acute and chronic safety of the biosense injection catheter system in porcine hearts.

Direct myocardial injection of therapeutic agents has been explored as a new method for myocardial revascularization. The integration of a 3D electromechanical mapping catheter with a retractable injection needle should allow for intramyocardial injection to identified sites, obviating the need for open heart surgery. This study assessed the procedural safety and performance characteristics of a novel guided catheter-based transendocardial injection system. The electromagnetic guidance system was coupled with a retrievable 27G needle for left ventricular endocardial injection. Using this system, we injected, transendocardially, methylene-blue (MB) dye tracer at a volume of 0.1 or 0.2 ml per injection in eight normal pigs. Animals were sacrificed acutely, at 1, 3, and 7 days (two animal in each time). Three animals served as controls. The injections were followed by coronary angiography and echocardiogram to assess possible ventricular or coronary perforation and wall motion abnormalities. CK-MB levels were measured up to 24 hr following the procedure. The animals were sacrificed at the assigned time for gross and histopathology evaluation. A total of 101 injections were made in all regions of the heart except the apex and the mitral valve. No animal died as a result of the mapping or injection procedures. Vital signs did not change relative to baseline after the mapping and injection procedures. CK-MB values did not increase over time and there was no evidence of sustained arrhythmia or hemodynamic compromise. There was no evidence of left ventricular or coronary perforation, global or regional wall motion abnormalities, or hemopericardium. On histologic evaluation, the estimated volume of tissue staining was greater than the volume of the injected MB dye due to dispersion of the injectate in the interstitial and intracellular fluid compartments. It is concluded that using this magnetic guidance catheter-based navigational system, it is feasible and safe to perform the transendocardial injection procedure. Thus, if it is determined that direct intramyocardial injection of drugs is a valid therapeutic strategy, this approach offers a clear advantage over surgically based transepicardial injection procedures. Cathet. Cardiovasc. Intervent. 48:447-453, 1999.

Animals↗
PubMed1999

Procedural results and late clinical outcomes following multivessel coronary stenting.

OBJECTIVES: To evaluate in-hospital and long-term clinical outcomes in a large consecutive series of patients undergoing percutaneous multivessel stent intervention. BACKGROUND: High restenosis and recurrent angina rates have limited the clinical outcomes of multivessel coronary angioplasty before stents were available to improve angioplasty results. METHODS: We evaluated in-hospital and long-term clinical outcomes (death, Q-wave myocardial infarction [MI], and repeat revascularization rates at one year) in 398 consecutive patients treated with coronary stents in two (94% of patients) or three native arteries, compared to 1,941 patients undergoing stenting procedure in a single coronary artery between January 1, 1994 and August 29, 1997. RESULTS: Overall procedural success was obtained in 96% of patients with two- or three-vessel stenting and in 970% of patients with single-vessel stent intervention (p = 0.36). Procedural complications were also similar (3.8% for multivessel versus 2.9% for single vessel, p = 0.14). During follow up, target lesion revascularization was 15% in multivessel and 16% in single-vessel interventions (p = 0.38), and repeat revascularization (calculated per treated patient) was also similar for both groups (20% vs. 21%, p = 0.73). There was no difference in death (1.4% vs. 0.7%, p = 0.26), and Q-wave MI (1.2% vs. 0%, p = 0.02) was lower following multivessel interventions. Overall cardiac event-free survival was similar for both groups (p = 0.52). CONCLUSIONS: Unlike previous conventional angioplasty experiences, multivessel stenting has (1) similar in-hospital procedural success and major complication rates and (2) similar long-term (one year) clinical outcomes compared with single-vessel stenting. Thus, stents may be a viable therapeutic strategy in carefully selected patients with multivessel coronary disease.

Angioplasty, Balloon, Coronary↗
PubMed1999

Granulomatous 'foreign body reactions' contribute to exaggerated in-stent restenosis.

BACKGROUND: Results of previous studies with stents coated with 'biocompatible' polymers showed that severe inflammatory reaction and subsequent in-stent restenosis may occur. OBJECTIVE: To evaluate the contribution of granulomatous reaction from uncoated stents to formation of in-stent neointimal hyperplasia. METHODS: Uncoated stainless-steel stents were implanted into 21 porcine coronary arteries without oversizing and harvested after 2 months (n = 6) or 6 months (n = 7). We compared the stents with granulomatous reaction with those without foreign-body reaction. RESULTS: Granulomatous reactions occurred in five 21 stents and resulted in there being significantly greater in-stent neointimal hyperplasia than there was with stents without foreign-body reaction (angiographic diameter stenosis 45 +/- 36 versus 16 +/- 16%, area of neointimal 3.30 +/- 1.4 versus 1.22 +/- 0.4 mm2, thickness of neointima 0.46 +/- 0.29 versus 0.11 +/- 0.09 mm, stenosed area 56 +/- 24 versus 20 +/- 7%, P < 0.01 for each comparison). This increase in amount of neointima was accompanied by significantly greater proliferating cell nuclear antibody staining (15 +/- 5 versus 3 +/- 2%, P < 0.05) in the presence of a granuloma near the stent struts. CONCLUSIONS: A localized granulomatous reaction is associated with a significant increase in amount of stent neointima and proliferation of cells. Thus, permanent stent implants may provoke granulomatous vascular reactions that may affect late-healing responses and clinical outcomes.

Animals↗
PubMed1999

Electromechanical characterization of myocardial hibernation in a pig model.

BACKGROUND: This study attempted to assess in-vivo electromechanical changes following gradual coronary artery occlusion in a pig ameroid constrictor model using a novel three-dimensional left ventricular mapping system. METHODS AND RESULTS: We measured unipolar and bipolar voltage potentials and local endocardial shortening in the ischemic lateral and non-ischemic anterior zones in animals at rest (n = 9) 5 weeks after the implantation of ameroid constrictors around the left circumflex artery. Echocardiography was used to assess regional contractility (percentage myocardial thickening), and an echo-contrast perfusion study was performed using acoustic densitometry methods. The ischemic lateral zone showed reduced myocardial perfusion at rest (peak intensity; 3.4 +/- 1.7 versus 20.7 +/- 14.8, P = 0.005), impaired mechanical function (percentage wall thickening 22 +/- 19% versus 40 +/- 11%, P = 0.03; local endocardial shortening 2.9 +/- 5.5% versus 11.7 +/- 2.1%, P = 0.002), and preserved electrical activity (unipolar voltage 12.4 +/- 4.7 versus 14.4 +/- 1.9 mV, P = 0.25; bipolar voltage 4.1 +/- 1.1 versus 3.8 +/- 1.5 mV, P = 0.62), compared with the anterior region. CONCLUSIONS: Gradual coronary artery occlusion resulting in regional reduced perfusion and function at rest (i.e. hibernating myocardium) is characterized by preserved electrical activity. An electromechanical left ventricular mapping procedure such as the one described here may be of diagnostic value for identifying the hibernating myocardium.

Animals↗
PubMed1999

Saline infusion via local drug delivery catheters is associated with increased neointimal hyperplasia in a porcine coronary in-stent restenosis model.

BACKGROUND: Catheter-based local drug delivery at the site of stent implantation has been proposed to reduce in-stent restenosis. We examined whether local delivery itself may cause additional vessel wall injury and negate the potential benefit of local drug delivery in a porcine coronary in-stent restenosis model. METHODS: Pigs were randomly assigned to no local delivery (controls, n = 10) or local saline infusion (5 ml) using commercially available catheters (n = 39; Dispatch catheter, Microporous Infusion catheter, and InfusaSleeve) prior to oversized (stent:artery ratio 1.2) coronary stent implantation. The amount of in-stent neointima was evaluated 4 weeks later with angiography and histology. RESULTS: There was no difference in vessel size or stent: artery ratio. However, at follow-up the local saline delivery group had significantly greater diameter stenosis (50 +/- 19% versus 25 +/- 17% in the controls, P < 0.01). Histology revealed similar injury scores but significantly greater neointimal area in the local saline group (3.61 +/- 1.11 mm2 versus 1.96 +/- 0.82 mm2 in the controls, P < 0.01). In a multivariate linear regression analysis, the use of the local delivery catheter was the only independent variable which was positively correlated with the amount of neointima (P = 0.0001). CONCLUSIONS: In this in-stent restenosis model, catheter-based local saline delivery was associated with significantly increased neointimal hyperplasia. Thus, for local drug delivery to reduce in-stent restenosis, the antiproliferative agent should be potent enough to compensate for the additional neointimal hyperplasia from the infusion itself.

Animals↗
PubMed1999

Severe spasm of the free radial artery graft in a patient undergoing high-risk angioplasty under percutaneous cardiopulmonary support.

This report illustrates a case of percutaneous intervention in a very high-risk patient who already had three previous bypass operations and was not a suitable candidate for further surgical revascularization. Since intra-aortic balloon pump insertion was contraindicated due to the origin of a radial graft from the descending aorta, percutaneous cardiopulmonary support (CPS) was used to perform the procedure. Thus, CPS proved useful in providing adequate hemodynamic support and allowed us to use adequate amount of antispastic drugs to relieve any spasm during the procedure. This case also highlights the need to use antispastic drugs before performing percutaneous interventions on arterial conduits, particularly radial artery grafts which are prone to vasospasm. Since the use of the radial artery for bypass surgery has recently been revived with considerable interest, perhaps more percutaneous interventional procedures may be performed in the future on arterial graft stenosis. We therefore recommend the routine use of vasorelaxant drugs in percutaneous interventions involving arterial grafts.

Aged↗
PubMed1999

Electromechanical characterization of acute experimental myocardial infarction.

OBJECTIVE: A new cardiac mapping system combines harmless magnetic field energy and tip-deflecting catheters (equipped with location sensors) to obtain real-time 3-dimensional electromechanical maps of the left ventricle endocardial surface without using x-ray fluoroscopy. This experimental study assessed electromechanical changes during acute coronary occlusion and reperfusion in a canine model. METHODS: Group 1 (n = 10) underwent coronary occlusion for 45 minutes followed by reperfusion (n = 6) and group 2 (n = 11) underwent coronary occlusion for 90 minutes. Endocardial peak-to-peak voltage amplitudes and local endocardial shortening values were measured in ischemic and non-ischemic zones at baseline, following coronary occlusion and reperfusion. RESULTS: In ischemic zones, local shortening was significantly reduced during coronary occlusion compared to baseline (Group 1: 4.7 +/- 2.0% at 45 minutes vs. 15.5 +/- 3.4%, p < 0.001, 6.2 +/- 2.1% at 90 minutes vs. 15.5 +/- 3.4%, p < 0.001; Group 2: 5.0 +/- 2.9% at 90 minutes vs. 13.9 +/- 3.3%, p = 0.007). Coronary occlusion caused a significant reduction in voltage potentials in the ischemic area (unipolar voltage at 45 minutes: 32.2 +/- 7.3 mV vs. 36.2 +/- 8.5 mV at baseline, p = 0.03; unipolar voltage at 90 minutes: 30.5 +/- 11.3 mV vs. 38.3 +/- 14.2 mV, p = 0.003; bipolar voltage at 45 minutes: 7.6 +/- 5.5 mV vs. 10.1 +/- 6.0 mV, p < 0.04; bipolar voltage at 90 minutes: 7.6 +/- 4.4 mV vs. 9.8 +/- 6.2 mV, p < 0.02). Voltage amplitudes were no longer reduced during reperfusion (unipolar voltage: 34.3 +/- 10.5 mV vs. 36.2 +/- 8.5 mV, p = 0.26; bipolar voltage: 9.1 +/- 4.5 mV vs. 10.1 +/- 6.0 mV at baseline, p = 0.37), or in non-ischemic regions during either coronary occlusion or reperfusion. CONCLUSIONS: Electromechanical mapping study provides unique insights into acute myocardial infarction and stunning by detection and localization of early electromechanical changes during coronary occlusion and/or reperfusion.

Animals↗
PubMed1999

Mechanical Approaches for Myocardial Angiogenesis.

Because angiogenesis appears to be a fundamental mechanism associated with direct myocardial revascularization (DMR) procedures, it seems natural to combine the overall field of DMR with angiogenesis therapy. Such myocardial treatment strategy can thus be termed "mechanical approach for myocardial angiogenesis." In this article, we review the myocardial response to various ablative energy sources in order to explore data indicative for angiogenesis in response to mechanical myocardial injury, or by using hybrid approaches, combining energy sources with proangiogenic pharmacotherapy.

Journal Article↗
PubMed1998

Procedural results and long-term clinical outcomes following coronary stenting in perimyocardial infarction syndromes.

Initial experiences with coronary stents in acute coronary syndromes have suggested higher risk of ischemic complications and stent thrombosis. We evaluated in-hospital and 1-year clinical outcomes of coronary stent implantation in perimyocardial infarction (MI) syndromes. We studied 334 consecutive patients undergoing stent interventions in the first week after acute MI. Stenting was performed within 24 hours (n = 31), within 1 to 3 days (n = 95), and within 4 to 7 days (n = 208). Stents were used to improve angioplasty results and to treat dissections and abrupt/threatened closure. Postprocedure anticoagulation regimens were aspirin, ticlopidine, and low molecular weight heparin. Overall procedural success was achieved in 93% of patients. Major in-hospital complications included death (1.0%), recurrent Q-wave MI (0.6%), and emergent bypass surgery (3.0%). Stent thrombosis occurred in 0.6% of patients. At follow-up, cardiac event-free survival was 80%, mortality 2.2%, recurrent MI 3.5%, and target lesion revascularization 11%. We conclude that coronary stenting in periinfarction syndromes was effective in achieving sustained clinical benefit up to 1 year with low morbidity and mortality. Thus, stents seem to be a viable therapeutic strategy in patients sustaining perimyocardial infarction syndromes.

Aged↗
PubMed1998

Comparison between left ventricular electromechanical mapping and radionuclide perfusion imaging for detection of myocardial viability.

BACKGROUND: A novel 3-dimensional left ventricular (LV) mapping system uses low-intensity magnetic field energy to determine the location of sensor-tipped electrode catheters within the LV. Using this system, we sought to distinguish between infarcted, ischemic, and normal myocardium by comparing LV electromechanical mapping data with myocardial perfusion imaging studies. METHODS AND RESULTS: Unipolar voltage potentials and local endocardial shortening (LS) were measured in 18 patients (mean age, 58+/-12 years) with symptomatic chronic angina having reversible and/or fixed myocardial perfusion defects on single photon emission computed tomography imaging studies using 201Tl at rest and 99mTc-sestamibi after adenosine stress. Overall, a significant difference in voltage potentials and LS values was found between groups (P<0.001 for each comparison by ANOVA). The average voltage potentials (14.0+/-2.0 mV) and LS values (12.5+/-2.8%) were highest when measured in myocardial segments (n=56) with normal perfusion and lowest (7.5+/-3.4 mV and 3.4+/-3.4%) when measured in myocardial segments with fixed perfusion defects (n=20) (P<0.0001). Myocardial segments with reversible perfusion defects (n=66) had intermediate voltage amplitudes (12.0+/-2.8 mV, P=0.048 versus normal and P=0.005 versus fixed segments) and LS values (10.3+/-3.7%, P=0.067 versus normal and P=0.001 versus fixed segments). CONCLUSIONS: In patients with myocardial ischemia, LV mapping, compared with myocardial perfusion imaging, shows (1) mild reduction of endocardial voltage potentials and LS in segments with reversible perfusion defects and (2) profound electromechanical impairment in segments with fixed perfusion defects. Thus, such an LV mapping procedure may allow the detection on-line of myocardial viability in the catheterization laboratory.

Aged↗
PubMed1998

Preliminary animal and clinical experiences using an electromechanical endocardial mapping procedure to distinguish infarcted from healthy myocardium.

BACKGROUND: A catheter-based left ventricular (LV) endocardial mapping procedure using electromagnetic field energy for positioning of the catheter tip was designed to acquire simultaneous measurements of endocardial voltage potentials and myocardial contractility. We investigated such a mapping system to distinguish between infarcted and normal myocardium in an animal infarction model and in patients with coronary artery disease. METHODS AND RESULTS: Measurements of LV endocardial unipolar (UP) and bipolar (BP) voltages and local endocardial shortening were derived from dogs at baseline (n=12), at 24 hours (n=6), and at 3 weeks (n=6) after occlusion of the left anterior descending coronary artery. Also, 12 patients with prior myocardial infarction (MI) and 12 control patients underwent the LV endocardial mapping study for assessment of electromechanical function in infarcted versus healthy myocardial regions. In the canine model, a significant decrease in voltage potentials was noted in the MI zone at 24 hours (UP, 42. 8+/-9.6 to 29.1+/-12.2 mV, P=0.007; BP, 11.6+/-2.3 to 4.9+/-1.2 mV, P<0.0001) and at 3 weeks (UP, 41.0+/-8.9 to 13.9+/-3.9 mV, P<0.0001; BP, 11.2+/-2.8 to 2.4+/-0.4 mV, P<0.0001). No change in voltage was noted in zones remote from MI. In patients with prior MI, the average voltage was 7.2+/-2.7 mV (UP)/1.4+/-0.7 mV (BP) in MI regions, 17.8+/-4.6 mV (UP)/4.5+/-1.1 mV (BP) in healthy zones remote from MI, and 19.7+/-4.4 mV (UP)/5.8+/-1.0 mV (BP) in control patients without prior MI (P<0.001 for MI values versus remote zones or control patients). In the canine model and patients, local endocardial shortening was significantly impaired in MI zones compared with controls. CONCLUSIONS: These preliminary data suggest that infarcted myocardium could be accurately diagnosed and distinguished from healthy myocardium by a reduction in both electrical voltage and mechanical activity. Such a diagnostic electromechanical mapping study might be clinically useful for accurate assessment of myocardial function and viability.

Animals↗
PubMed1998

Impact of stents on clinical outcomes in percutaneous left main coronary artery revascularization.

Despite effective treatment of left main coronary artery (LMCA) disease by coronary bypass, there is still need for treatment of the LMCA due to progression of disease or bypass graft failure. We compared the in-hospital and follow-up (1-year) outcomes of patients with LMCA stenosis treated with stents (n = 88), with a matched group of patients undergoing LMCA non-stent procedures (n = 36). Ninety-seven percent of patients in each group underwent previous coronary bypass. Procedural success (angiographic success without major in-hospital complications) tended to be higher in stent patients than in their non-stent counterparts (98% vs 92%, p = 0.12), and overall procedural complications were higher for the non-stent group (5.4% vs 0%, p = 0.03). The incidence of non-Q-wave myocardial infarction was higher in patients with the LMCA treated with stents than in non-stent patients (13% vs 2.7%, p = 0.09). There was no difference in death or Q-wave myocardial infarction between the 2 groups during follow-up. Overall target lesion revascularization at 1 year was 15% after LMCA stenting, and 18% in non-stent patients (p = 0.71). Also, any cardiac event-free survival (including death, Q-wave myocardial infarction, coronary bypass, or angioplasty) was similar for both groups (78% for stents vs 76% for non-stents, p = 0.85). We conclude that in patients undergoing LMCA interventions, stents reduce major hospital complications, but may not significantly reduce repeat revascularization or major cardiac events at 1 year compared with non-stent LMCA procedures.

Aged↗