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Biomedical subjects

H R Phillips

Publications and source records attributed to H R Phillips.

At least 55 records · Page 3Linked to original sources
PubMed1992

Early and late outcome following deployment of a new flexible tantalum intracoronary stent in dogs.

A new radiopaque, highly flexible balloon-expandable tantalum stent was tested. Thirty-six of 40 stents were successfully deployed percutaneously in the coronary arteries of 31 dogs. The dogs were given aspirin before, intravenous heparin during, and aspirin alone after the procedure. One dog died at 24 hours because of coronary occlusion following traumatic implantation. Four dogs were put to death early, revealing re-endothelialization by 9 days. Eleven dogs were put to death from 2 weeks to 9 months during long-term follow-up, showing all vessels widely patent with the stent uniformly embedded within a stable neointimal layer. Follow-up arteriography showed patency in all remaining stents up to 1 year, with no perforation or aneurysm formation. Four stents were placed into canine peripheral arteries and were removed percutaneously after deployment. Pathology revealed no significant trauma to involved vessels. This tantalum stent exhibits feasibility of percutaneous deployment, early neointimal formation, low thrombogenicity on long-term aspirin therapy alone, and patency up to 1 year in this canine model.

Animals↗
PubMed1992

Prognosis in cardiogenic shock after acute myocardial infarction in the interventional era.

OBJECTIVES: The purpose of this study is to describe the outcome in cardiogenic shock treated with aggressive reperfusion therapy and to identify factors predictive of in-hospital and long-term mortality. BACKGROUND: Cardiogenic shock is the most common cause of death in patients admitted to the coronary care unit. Although studies have reported lower mortality rates in shock treated with angioplasty, few studies have described a cohort of patients with shock who were not selected because they were most likely to benefit from reperfusion therapy. METHODS: A consecutive series of 200 patients admitted with acute myocardial infarction complicated by cardiogenic shock were studied. RESULTS: The in-hospital mortality rate was 53%. Variables with significant univariable association with in-hospital death included patency of the infarct-related artery, patient age, lowest cardiac index, highest arteriovenous oxygen difference and left main coronary artery disease. The most important independent predictors of in-hospital death were patency of the infarct-related artery, cardiac index and peak creatine kinase, MB fraction. The mortality rate in patients with patent infarct-related arteries was 33% versus 75% in those with closed arteries and 84% in those in whom arterial patency was unknown. Patients who survived to hospital discharge were followed up for a median of 2 years, with a mortality rate of 18% after 1 year. The best descriptors of the relation between these variables and postdischarge mortality included age, peak creatine kinase, ejection fraction and patency of the infarct-related artery. CONCLUSIONS: In a large consecutive series of patients with cardiogenic shock with complete follow-up, patency of the infarct-related artery was most strongly associated with in-hospital and long-term mortality. This finding supports an aggressive interventional strategy in patients with cardiogenic shock.

Academic Medical Centers↗
PubMed1992

Renal artery stenosis: prevalence and associated risk factors in patients undergoing routine cardiac catheterization.

The purposes of this study were to determine the prevalence of angiographically significant renal artery stenosis in a patient population referred for diagnostic cardiac catheterization and to develop a model that predicts the highest-risk subset of patients who have significant renal artery narrowing. A prospective validation cohort study was undertaken in a referral-based university hospital. After left ventriculography, abdominal aortography was performed to screen for the presence of renal artery disease. A convenience sample of 1,302 of 1,651 consecutive patients undergoing diagnostic cardiac catheterization were enrolled in the study. Of the 1,302 abdominal aortograms performed, 1,235 (95%) were deemed of adequate quality for the evaluation of renal artery anatomy. Renal artery disease was identified in 30% of the patients. Insignificant renal artery stenosis was found in 187 (15%) and significant (greater than or equal to 50% diameter narrowing) stenosis was found in 188 (15%). Significant unilateral disease was present in 11%, and bilateral disease was present in 4%. By univariable and multivariable logistic regression analysis, the association of both clinically and catheterization-derived variables with renal artery disease was assessed. Multivariable predictors included age, severity of coronary artery disease, congestive heart failure, female gender, and peripheral vascular disease. Hypertension was not an associated variable. These data reveal the previously undetected high prevalence of renal artery disease in patients undergoing cardiac catheterization and provide clinical and angiographic features that assist in predicting its presence.

Aged↗
PubMed1991

Intracoronary ultrasound evaluation of interventional technologies.

The feasibility and applicability of intravascular ultrasound (IVUS) of the coronary arteries were evaluated in 65 patients undergoing 70 coronary interventional procedures. Morphologic and quantitative analyses were performed with a mechanically rotated IVUS catheter (4.8Fr, 20 MHz) and with orthogonal view cineangiography. A semiautomated edge-detection algorithm was used for cineangiographic quantification. Coronary interventions included 45 percutaneous transluminal coronary angioplasties, 9 excimer lasers, 11 directional coronary atherectomies, 3 rotational atherectomies and 2 stents. Most lesions consisted of a mixture of plaque composition (hard, n = 30; soft, n = 64). Other unique morphologic data by IVUS were plaque topography (eccentric, n = 34; concentric, n = 36) and vessel dissection (IVUS [n = 29] versus angiography [n = 14], p less than 0.05). Postprocedure minimal lumen diameter and cross-sectional area measured by IVUS were larger and poorly correlated with angiography (r = 0.28, standard error of the estimate = 0.52 mm; r = 0.08, standard error of the estimate = 1.0 cm2, respectively). IVUS is more sensitive than angiography when assessing postintervention lesion characteristics including vessel dissection and plaque morphology. Catheter-based ultrasound appears to be a useful adjunct to contrast angiography when evaluating and comparing the therapeutic impact of conventional percutaneous transluminal coronary angioplasty with new technologies.

Algorithms↗
PubMed1990

Usefulness of a pericardial friction rub after thrombolytic therapy during acute myocardial infarction in predicting amount of myocardial damage. The TAMI Study Group.

To evaluate the clinical incidence and outcomes of patients with pericarditis after thrombolytic therapy, 810 patients were prospectively studied during acute myocardial infarction (AMI). Pericarditis was defined as the presence of a pericardial friction rub during the hospital course. Only 5% of patients developed a rub during AMI, a low percent compared with that in the prethrombolytic era. A pericardial friction rub more often occurred in the setting of an anterior wall AMI. Patients with, compared to those without, a pericardial friction rub had lower ejection fractions (45 vs 51%, p = 0.002); worse regional left ventricular function (-3.2 vs 2.7, standard deviation per chord); higher in-hospital mortality (15 vs 6%, p = 0.056); a higher frequency of power failure (83 vs 57%); a higher frequency of anterior wall location of the AMI (53% of cases, p = 0.002); and a higher frequency of 3-vessel disease. Therefore, although the frequency of a pericardial friction rub was low (5%) compared with that in the prethrombolytic era, its occurrence denotes more extensive myocardial damage with a worse clinical outcome. Perhaps with successful reperfusion of the infarct-related vessel, transmural myocardial necrosis is prevented and with it the development of pericarditis. Cardiac tamponade did not occur clinically in any patient who developed a pericardial friction rub.

Female↗
PubMed1990

Results of high dose intravenous urokinase for acute myocardial infarction.

To determine the outcome of patients after treatment with high-dose intravenous urokinase (3 million U) 102 patients were prospectively evaluated in the setting of acute myocardial infarction. The first 61 patients received intravenous urokinase as a continuous infusion and the last 41 patients were treated with an initial 1.5 million U intravenous bolus. Sixty-two percent of all patients had patent infarct-related arteries by the time of immediate angiography (median time 2.2 hours), which was performed in all patients. There was no significant difference in patency rates between patients treated with or without an initial intravenous bolus. Twenty-eight (28%) patients developed clinical evidence of recurrent ischemia (death, reocclusion, emergency angioplasty, urgent bypass surgery) during hospitalization, whereas only 7 (7%) developed angiographically documented reocclusion. Of 28 patients who failed to achieve successful reperfusion at the time of immediate catheterization, rescue angioplasty was technically successful in establishing reperfusion in all but 1 patient. No significant improvement in median global left ventricular function was seen between immediate (48%) and follow-up catheterization (48%). Significant bleeding complications were unusual except in 1 patient who experienced an intracranial hemorrhage. Eight (8%) patients died during hospitalization. Therefore, the use of high-dose intravenous urokinase in patients with acute myocardial infarction is associated with a 62% patency rate, a low incidence of reocclusion and bleeding complications and a high technical success rate with rescue angioplasty at the time of immediate catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

A rapid, effective technique for retrograde crossing of valvular aortic stenosis using standard coronary catheters.

Retrograde crossing of valvular aortic stenosis can be challenging even to experienced angiographers. In 446 of 447 consecutive patients with aortic stenosis catheterized during the past 3 years, a technique using a standard Judkins right coronary catheter and a floppy straight tipped guide wire was successful in rapidly and efficiently crossing these pathologically distorted valves in retrograde fashion. Once the valve was crossed, the coronary catheter was replaced with a pigtail catheter for pressure and ventriculography. The majority of these valves required less than 2 min to cross using this technique. This method is valuable in limiting the time required for catheterization, thus helping to reduce procedure related morbidity in these oftimes critically ill patients.

Aged↗
PubMed1989

Repeat percutaneous transluminal coronary angioplasty and predictors of recurrent restenosis.

One hundred seventeen consecutive patients undergoing repeat percutaneous transluminal coronary angioplasty (PTCA) were studied to assess procedural success and recurrent restenosis rates. Clinical, anatomic and procedural variables were examined as predictors of recurrent restenosis using stepwise logistic regression analysis. Primary success was achieved in 114 patients (97.5%). One patient (0.8%) died after acute occlusion. No other in-hospital complications were encountered. After a mean follow-up interval of 218 +/- 160 days, 72 of 114 successfully dilated patients (63%) remained angina free. There were no late deaths. Three patients (2.6%) experienced a late myocardial infarction. Follow-up arteriography was performed in 100 patients (88%), of whom 32% had recurrent restenosis (greater than 50% luminal diameter narrowing). On univariate analysis, the presence of 3 clinical variables at repeat PTCA was associated with significantly higher recurrent restenosis rates compared with their absence, that is, unstable angina (48 vs 20%, p = 0.003), diabetes (61 vs 26%, p = 0.003) and hypertension (46 vs 18%, p = 0.003). Patients with recurrent restenosis had a shorter interval between first and second PTCA compared with those who remained patent (136 +/- 116 vs 214 +/- 163 days, p = 0.018). Multivariate analysis confirmed unstable angina, diabetes and hypertension as independent predictors of recurrent restenosis. Repeat PTCA may be performed for restenosis with a high likelihood of success and low incidence of complications. The rate of recurrent restenosis is similar to that reported for initial angioplasty. Patients with unstable angina, diabetes and hypertension appear to be at higher risk for recurrent restenosis.

Aged↗
PubMed1988

Perfusion balloon catheter.

An autoperfusion balloon catheter was developed to allow passive myocardial perfusion during balloon inflation, through a central lumen and multiple side holes in the shaft proximal and distal to the balloon. This report reviews preliminary experimental animal data and initial human clinical experience with this device. In our first study with this device, the duration of inflation in dogs was compared with the maximal duration of inflation using a standard angioplasty catheter. Coronary arteriography was performed to demonstrate distal coronary blood flow through the perfusion balloon catheter. Electrocardiographic recordings and repeated left ventriculograms were performed to detect evidence of ischemia during standard and perfusion and balloon catheter inflations. The average inflation time was 3 +/- 1 minute for the standard catheter and 37 +/- 10 minutes for the perfusion catheter. Each dog had evidence of severe myocardial ischemia during standard inflation, yet none of the animals had ST-segment elevation, ventricular arrhythmia or wall motion abnormality during dilatation with the perfusion catheter. In a second experiment, the effect of prolonged balloon inflations (30 minutes) on intimal hyperplasia was evaluated in the rabbit model. Results of this study showed reduction of intimal and medial hyperplasia after 4 weeks in iliac arteries in rabbits treated with prolonged inflations compared with the contralateral vessel in rabbits treated with standard angioplasty. Initial clinical results from patients treated with this new catheter are presented. The availability of an effective autoperfusion catheter should allow for testing the hypothesis that prolonged inflations could alter the acute angioplasty success rate and long-term restenosis rate.

Angioplasty, Balloon↗
PubMed1988

Helicopter transport of patients during acute myocardial infarction.

Initial experience with a regional system of emergency helicopter transport of patients with acute myocardial infarction (AMI) referred for emergent cardiac catheterization and percutaneous transluminal coronary angioplasty (PTCA) is described. Two hundred fifty patients with AMI were transported from within a 150-mile radius to Duke University Medical Center over a 15-month period. All patients were within 12 hours of onset of symptoms. Thrombolytic therapy was administered to 240 (96%) patients (72% before or in-flight). The time to administration of thrombolytic therapy ranged from 30 to 120 minutes (median 180), while the time to arrival in the interventional catheterization laboratory ranged from 105 to 815 minutes (median 300). The flight time was 12 to 77 minutes (median 31). Most patients had 1- or 2-vessel coronary artery disease; the baseline ejection fraction ranged from 27 to 70% (median 42). Transient hypotension was the most common complication both pre-flight and in-flight. Third-degree atrioventricular block and nonsustained ventricular tachycardia were the next most common complications. Ventricular fibrillation or sustained ventricular tachycardia occurred before takeoff in 38 patients (15%). No patients had ventricular fibrillation, asystole or respiratory arrest during transport. Fluid boluses for hypotension were the most common intervention. Five patients required cardiopulmonary resuscitation in-flight; 3 before lift-off and 2 required a brief period of cardiopulmonary resuscitation during sustained ventricular tachycardia. Fourteen patients had pressor therapy, military antishock trousers or both to maintain adequate blood pressure. Neither cardioversion, defibrillation nor intubation were performed in-flight. Thus, inflight complications are infrequent and can be managed en route to an intervention center.(ABSTRACT TRUNCATED AT 250 WORDS)

Aircraft↗
PubMed1988

Late restenosis after emergent coronary angioplasty for acute myocardial infarction: comparison with elective coronary angioplasty.

The late restenosis rate after emergent percutaneous transluminal coronary angioplasty for acute myocardial infarction was assessed by performing outpatient follow-up cardiac catheterization in 79 (87%) of 91 consecutive patients who had been discharged from the hospital with a successful coronary angioplasty. The majority of patients (90%) received high dose intravenous thrombolytic therapy with streptokinase in addition to angioplasty. Similar follow-up data were obtained in 206 (90%) of 228 consecutive patients who had successful elective angioplasty during the same period. The interval from angioplasty to follow-up was 28 +/- 9 weeks for the myocardial infarction group and 30 +/- 11 weeks for the elective group. Baseline clinical variables were similar for both the myocardial infarction and elective groups except for a higher percentage of men in the infarction group (81 versus 63%, p = 0.001). The number of coronary lesions undergoing angioplasty and the incidence of intimal dissection were similar, but multivessel angioplasty was more common in the elective group (13 versus 4%, p = 0.02). The rate of in-hospital reocclusion was higher in the patients receiving angioplasty for myocardial infarction (13 versus 2%, p = 0.0001). At the time of late follow-up after hospital discharge, the patients with myocardial infarction were more often asymptomatic (79 versus 55%, p = 0.0001), and the rate of angiographic coronary restenosis was lower for the infarction group both overall (19 versus 35%, p = 0.006) and when multivessel angioplasty patients were excluded (19 versus 33%, p = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗