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Biomedical subjects

M F Shiu

Publications and source records attributed to M F Shiu.

At least 19 recordsLinked to original sources
PubMed2002

Early experience with a helical coronary thrombectomy device in patients with acute coronary thrombosis.

OBJECTIVE: To report our experience with a new thrombectomy device (X-SIZER(TM)) in patients with angiographically visible thrombus or total coronary occlusion in the setting of acute coronary syndromes. DESIGN: A safety and feasibility study in the use of the X-SIZER during intervention in patients with acute coronary syndromes. PATIENTS: 35 patients, age range 31 to 83 years (mean 60). SETTING: University Hospitals of Coventry and Warwickshire NHS Trust (tertiary referral centre). INTERVENTIONS: The indication for intervention was primary or salvage percutaneous coronary intervention for acute myocardial infarction in 17 of the 35 patients; unstable angina or non-ST-elevation myocardial infarction in 10; and unstable postinfarct angina in eight. Abciximab was given in 11 patients. MAIN OUTCOME MEASURES: Device success (successful deployment of the device at the site of the lesion with resultant improvement in TIMI flow); clinical success (no residual stenosis at the end of the procedure with no in-hospital major adverse coronary events). RESULTS: Successful use of the device was achieved in 26 of the 35 cases. It failed to cross the lesion in five and failed to improve TIMI flow despite crossing the lesion in four. Clinical success was achieved in 30 of the 35 cases. Device related complications occurred in two cases (vessel perforation) and there was one intraprocedural death (acute myocardial infarction with cardiogenic shock). CONCLUSIONS: Thrombectomy with the X-SIZER catheter system appears promising in percutaneous coronary intervention where thrombus extraction is considered necessary before stent implantation.

Adult↗
PubMed2001

Evaluation of patient characteristics and utilisation of invasive cardiac procedures in a UK ethnic population with unstable angina pectoris.

OBJECTIVES: To evaluate patient characteristics and utilisation of invasive cardiac procedures in a UK ethnic population with unstable angina pectoris (UAP). DESIGN: Retrospective, observational study. SETTING: Tertiary referral cardiology centre in the United Kingdom serving a large Asian ethnic population. SUBJECTS: White and Asian patients undergoing PTCA for UAP over a 2.5-year period at a UK referral cardiology centre from a comprehensive PTCA database. Data were also collated for all emergency admissions with unstable angina, or angina (type unspecified), to our institute. MAIN OUTCOME MEASURES: Demographic and angiographic characteristics of patients undergoing PTCA. Frequency of usage of invasive cardiac procedures was determined in emergency angina admissions. RESULTS: From January 1997 to July 1999, 435 White and 36 Asian patients underwent PTCA for UAP at our institute. Asian patients were on average 4.4 years younger (P=0.015), had 19.3% more diabetes (P=0.003) and 19.7% less smoking (P=0.007). Trends to more single vessel disease in Whites and more double vessel disease in Asians were observed, with similar rates of triple vessel disease. Interestingly, Asians also had trends towards more left-sided coronary artery disease and revascularisation, smaller vessels and less bail-out stenting. Asian patients were significantly less likely to undergo coronary angiography, OR 0.64 (CI 0.45-0.91, P=0.012), during the index admission, and showed a trend to less PTCA. CONCLUSIONS: Asian patients with unstable angina pectoris appear to have clinical and angiographic differences from their White counterparts, and are less likely to have invasive cardiac procedures deployed. The reasons for these observations require elucidation and the prognostic significance of these findings is uncertain.

Aged↗
PubMed1999

Coronary pseudo-lesions induced in the left anterior descending and right coronary artery by the angioplasty guide-wire.

New lesions appearing during coronary angioplasty may be due to a number of causes including spasm, dissection, embolisation, thrombosis and creation of a pseudo-lesion. The term "coronary pseudo-lesions" has been given to describe artefactual lesions occurring during percutaneous transluminal coronary angioplasty and induced by the angioplasty guide-wire and/or balloon as a result of straightening of the vessel's curvature. No specific treatment is required as they resolve completely on removal of the angioplasty wire. Few modern texts of interventional cardiology contain description of this important phenomenon and we suspect that they pass largely unrecognised. All angioplasty operators should become familiar with this complication as failure to do so may lead to inappropriate intervention with attendant increase in risk to the patient. We report three cases of coronary pseudo-lesion. In two cases affecting the right coronary artery and in the third the left anterior descending coronary artery. Pseudo-lesions affecting the right coronary artery have been previously reported in the literature however pseudo-lesion affecting the left anterior descending artery has not been described. The possible mechanisms of this phenomenon and its management are discussed.

Aged↗
PubMed1999

Coronary artery stenting in unstable angina pectoris: a comparison with stable angina pectoris.

OBJECTIVE: To compare early complication rates in unselected cases of coronary artery stenting in patients with stable v unstable angina. SETTING: Tertiary referral centre. PATIENTS: 390 patients with stable angina pectoris (SAP) and 306 with unstable angina (UAP). Patients treated for acute myocardial infarction (primary angioplasty) or cardiogenic shock were excluded. INTERVENTIONS: 268 coronary stents were attempted in 211 patients (30.3%). Stents used included AVE (63%), Freedom (14%), NIR (7%), Palmaz-Schatz (5%), JO (5%), and Multilink (4%). Intravascular ultrasound was not used in any of the cases. All stented patients were treated with ticlopidine and aspirin together with periprocedural unfractionated heparin. RESULTS: 123 stents were successfully deployed in 99 SAP patients v 132 stents in 103 UAP patients. Failed deployment occurred with nine stents in SAP patients, v four in UAP patients (NS). Stent thrombosis occurred in four SAP patients and 11 UAP patients. Multivariate analysis showed no relation between stent thrombosis and clinical presentation (SAP v UAP), age, sex, target vessel, stent length, or make of stent. Stent thrombosis was associated with small vessel size (p < 0.001) and bailout stenting (p = 0.01) compared with elective stenting and stenting for suboptimal PTCA, with strong trends toward smaller stent diameter (p = 0.052) and number of stents deployed (p = 0.06). Most stent thromboses occurred in vessels < 3 mm diameter. CONCLUSIONS: Coronary artery stenting in unstable angina is safe in vessels >/= 3 mm diameter, with comparable initial success and stent thrombosis rates to stenting in stable angina.

Angina Pectoris↗
PubMed1998

Coronary spasm in acute myocardial infarction.

A 30 year old man had an acute anterolateral myocardial infarction following which he developed unstable angina requiring percutaneous transluminal coronary angioplasty. He subsequently developed further angina with recurrence of coronary artery lesions that were reversed by intracoronary nitrate. A diagnosis of prinzmetal (vasospastic) angina was made and this had been the apparent cause of his myocardial infarction. He was treated with a calcium antagonist and an oral long acting nitrate with resolution of symptoms. He remained well and symptom free, and was reviewed in the outpatient clinic six weeks after discharge without problems.

Adult↗
PubMed1997

[Low molecular weight heparin, reviparin, after PTCA: results of a randomized double-blind, standard heparin and placebo controlled multicenter study (REDUCE Study].

BACKGROUND: Unfractionated heparin and its low molecular fragments possess antiproliferative effects and have been shown to reduce neointimal smooth muscle cell migration and proliferation in response to vascular injury in experimental studies. OBJECTIVES: The specific objective of the REDUCE trial was to evaluate the effect of a low molecular weight heparin on the incidence and occurrence of restenosis in patients undergoing percutaneous transluminal coronary angioplasty. METHODS: The REDUCE trial is an international prospective, randomized, double-blind, multicenter study. Twenty-six centers in Europe and Canada enrolled 625 patients with single lesion coronary artery obstructions suitable for PTCA. Three hundred and six patients received reviparin as a 7000 U bolus before PTCA followed by 10,500 U as an infusion over 24 hours and then twice a day 3500 U s.c. application for 28 days. The 306 patients in the control group received a bolus of 10,000 U unfractionated heparin followed by an infusion of 24,000 U over 24 hours. These patients then received 28 days of s.c. placebo injections. The primary endpoints were efficacy (defined as a reduction in the incidence of major adverse events, i.e., death, myocardial infarction, need for reintervention or bypass surgery), absolute loss of minimal luminal diameter, and incidence of restenosis during the observation period of 30 weeks after PTCA. RESULTS: Using the intention-to-treat analysis for all patients, 102 patients (33.3%) of the reviparin group and 98 patients (32%) of the control group have reached a primary clinical endpoint (relative risk = 0.98; 95% confidence limit, 0.88-1.09; p = 0.707). Likewise, no difference in late loss of minimal luminal diameter was evident for either group. Acute events within 24 hrs occurred in 3.9% of the reviparin group and in 8.2% of the control group (relative risk = 0.49; 95% confidence limit, 0.26-0.92; p = 0.027) during or immediately after the initial procedure. In the control group, 8 major bleedings occurred, and in the reviparin group, 7 major bleeding complications were observed within 35 days after PTCA. CONCLUSIONS: Reviparin use during and after coronary angioplasty did not reduce the occurrence of major clinical events or the incidence of angiographic restenosis over 30 weeks.

Adult↗
PubMed1996

Low molecular weight heparin (reviparin) in percutaneous transluminal coronary angioplasty. Results of a randomized, double-blind, unfractionated heparin and placebo-controlled, multicenter trial (REDUCE trial). Reduction of Restenosis After PTCA, Early Administration of Reviparin in a Double-Blind Unfractionated Heparin and Placebo-Controlled Evaluation.

OBJECTIVES: The specific objective of the REDUCE trial was to evaluate the effect of low molecular weight heparin on the incidence and occurrence of restenosis in patients undergoing percutaneous transluminal coronary angioplasty (PTCA). BACKGROUND: Unfractionated heparin and its low molecular weight fragments possess antiproliferative effects and have been shown to reduce neointimal smooth muscle cell migration and proliferation in response to vascular injury in experimental studies. METHODS: The REDUCE trial is an international prospective, randomized, double-blind, multicenter study. Twenty-six centers in Europe and Canada enrolled 625 patients with single-lesion coronary artery obstructions suitable for PTCA. Three hundred six patients received reviparin as a 7,000-U bolus before PTCA, followed by 10,500 U as an infusion over 24 h and then twice-daily 3,500-U subcutaneous application for 28 days. The 306 patients in the control group received a bolus of 10,000 U of unfractionated heparin followed by an infusion of 24,000 U over 24 h. These patients then underwent 28 days of subcutaneous placebo injections. The primary end points were efficacy (defined as a reduction in the incidence of major adverse events [i.e., death, myocardial infarction, need for reintervention or bypass surgery]), absolute loss of minimal lumen diameter and incidence of restenosis during the observation period of 30 weeks after PTCA. RESULTS: Using the intention to treat analysis for all patients, 102 (33.3%) in the reviparin group and 98 (32%) in the control group have reached a primary clinical end point (relative risk [RR] 1.04, 95% confidence interval [CI] 0.83 to 1.31, p = 0.707). Likewise, no difference in late loss of minimal lumen diameter was evident for both groups. Acute events within 24 h occurred in 12 patients (3.9%) in the reviparin group and 25 (8.2%) in the control group (RR 0.49, 95% CI 0.26 to 0.92, p = 0.027) during or immediately after the initial procedure. In the control group, eight major bleeding complications occurred, and in the reviparin group, seven were observed within 35 days after PTCA. CONCLUSIONS: Reviparin use during and after coronary angioplasty did not reduce the occurrence of major clinical events or the incidence of angiographic restenosis over 30 weeks.

Angioplasty, Balloon, Coronary↗
PubMed1992

Pleural effusion following coronary perforation during balloon angioplasty: an unusual presentation of the postpericardiotomy syndrome.

We report on the development of features of the postpericardiotomy syndrome following coronary perforation during balloon angioplasty, in a patient that was managed conservatively. The case illustrates that while cardiac tamponade does not invariably follow coronary perforation, late consequences derived from this complication may occur. It also widens the spectrum of conditions where the postpericardiotomy syndrome has been observed.

Angina Pectoris↗
PubMed1992

Referral decisions.

Explore the source record for details and available documents.

Angioplasty, Balloon, Coronary↗
PubMed1991

Evaluation of a theoretical Doppler index to noninvasively estimate peak dP/dt using continuous wave Doppler ultrasound of ascending aortic flow in man.

A theoretical formula for calculation of peak dP/dt was derived using parameters obtained from continuous wave Doppler echocardiography signals of aortic blood flow. The direct proportional relationship between the main variables of this formula and invasively measured peak dP/dt was validated in 20 patients undergoing routine diagnostic cardiac catheterization. Doppler signals of aortic flow were obtained simultaneously to invasive pressure recordings with a 2 MHz continuous wave transducer via the suprasternal echocardiographic window. The Doppler signals were recorded on magnetic tape and measurements were made with digital calipers by two independent, blinded observers. The following parameters were measured: peak velocity (V) and time from onset of ejection to peak velocity (T). V2/T, the variable of the derived formula, was calculated for each of the observer's measured parameters and showed a very high interobserver correlation. The two observers' measurements of each parameter were averaged for each patient and the resulting mean was used in calculating the V2/T and mean acceleration. 4. A good correlation of V2/T with invasively measured peak dP/dt was obtained. Our derived index of left ventricular function showed a higher correlation with peak dP/dt compared to other Doppler indices of ventricular function. V2/T may provide a noninvasive method for estimating peak dP/dt.

Aorta↗
PubMed1991

Ebstein's anomaly associated with splenomegaly and reversible hypersplenism.

A case of Ebstein's anomaly associated with chronic right heart failure, hepatosplenomegaly, and the haematological features of hypersplenism is presented. The haematological abnormalities were corrected after tricuspid valve replacement but recurred with the reemergence of clinical features of right heart failure.

Adult↗
PubMed1991

Changes in Doppler indices of cardiac function during and after percutaneous transluminal coronary angioplasty.

OBJECTIVE: To assess the sensitivities of Doppler indices to changes in global cardiac function during and after controlled myocardial ischaemia induced by coronary angioplasty. DESIGN: Continuous wave Doppler signals of aortic flow were recorded during coronary angioplasty. The following Doppler indices of cardiac function were measured before, during, and after balloon inflation: V (peak velocity), MA (mean acceleration), V2/T (T = time from onset to peak ejection), and MD (minute distance corrected for baseline heart rate). SETTING: A tertiary care cardiological unit in a university hospital. PATIENTS: Sixteen patients undergoing coronary angioplasty of the left anterior descending coronary artery. Eight patients had multivessel disease. MAIN OUTCOME MEASURES: The primary outcome measures were planned before data collection began. RESULTS: 12 patients showed a significant fall of three or more Doppler indices from their baseline values during balloon inflation. This occurred in all patients with multivessel disease. The Doppler indices V2 T, MD, V, and MA fell by 43.7%, 37.7%, 27.4%, and 23% respectively from their baseline values (p less than 0.0001). The relative sensitivities of the Doppler indices to ischaemia were V2/T greater than MD (p less than 0.02), MD greater than (p less than 0.001), and V greater than MA (p less than 0.01). The impairment of global left ventricular function resulting from brief balloon inflation during single vessel angioplasty was reversible in all the patients. CONCLUSIONS: The Doppler indices V2/T, MD, V, and MA are all sensitive, in order of magnitude, to falls in global cardiac function resulting from ischaemia. They may prove useful for assessing cardiac function during ischaemia in the clinical setting.

Adult↗
PubMed1991

Release of creatine kinase-MB and cardiac specific troponin-I following percutaneous transluminal coronary angioplasty.

Up to 20% of patients undergoing successful coronary angioplasty have been shown to have a mild elevation of creatine kinase-MB (CK-MB). The purpose of this study was to investigate the relationship between clinical and angioplasty procedural variables and circulating markers for cardiac injury. We measured both CK-MB and totally cardiac-specific troponin inhibitory protein (Tn-I) in 22 patients immediately before and at an average time of 10 h 36 min following successful angioplasty. Of these patients 16 had stable angina, six had unstable angina and none had recent myocardial infarction. Four patients had minor complications associated with the procedure (prolonged chest pain, limited coronary artery dissection) but none of these patients had increases in either CK-MB or Tn-I. In two patients there was a mild increase in enzyme-activity assayed CK-MB but none of the 22 patients had significant elevation of mass-assayed CK-MB or cardiac-specific Tn-I. This study supports the view that no significant myocardial damage occurs as a result of successful coronary angioplasty irrespective of the stability of the coronary artery disease. This study confirms the known discrepancies between results obtained by immunoassay and immunoinhibition enzyme assay, due to the false-positive results which can be yielded by the latter technique.

Angina Pectoris↗