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M R Pitney

Publications and source records attributed to M R Pitney.

14 recordsLinked to original sources
PubMed1998

Impact of an aggressive coronary stenting strategy on the incidence of target lesion revascularization.

Coronary stenting has been shown to reduce the incidence of target lesion revascularization (TLR) compared with balloon angioplasty in highly selected patients. However, the impact of an aggressive coronary stenting strategy in unselected patients on the overall incidence of TLR is unclear. We assessed the effect of increased stenting by comparing long-term results in consecutive patients who underwent successful percutaneous revascularization (with or without stents) during June to December 1995 (n=347) with those in June to December 1996 (n=401). Stents were used in 22.5% of patients in 1995 versus 66.1% in 1996 (p <0.0001). Mean age of the patients was 62+/-11 years (71% men) in 1995 versus 63+/-10 in 1996 (76% men) (p=NS). The 2 groups were well matched with the exception that the 1996 cohort included more patients with unstable coronary syndromes (25% in 1995 vs 34% in 1996 (p=0.003). There was no significant difference in the incidence of in-hospital adverse events. After 12 months of follow-up (complete in 95% of patients in each group), the incidence of TLR was significantly lower in the 1996 cohort than in the 1995 cohort (8.5% vs 14.7%, p=0.0075). This was mainly due to reduced requirement for repeat angioplasty in 1996 patients compared with 1995 (6.5% vs 11.8%, p=0.011). It is concluded that in an unselected patient population, an aggressive coronary stenting strategy was associated with a marked overall reduction in requirement for TLR over a 12-month period.

Aged↗
PubMed1997

Simultaneous use of a diagnostic catheter to facilitate stent deployment in aorto-ostial artery stenosis: a case report.

Correct positioning of a stent at an ostial lesion can be difficult due to poor visualisation once the guide is backed out of the artery to allow deployment. This case report illustrates a technique whereby the simultaneous use of a diagnostic catheter allows optimal visualisation of stent position, whilst maintaining a stable guide position well away from the stent.

Aged↗
PubMed1996

Activated clotting time differential is a superior method of monitoring anticoagulation following coronary angioplasty.

The standard high-range activated clotting time (sHR ACT) is used to monitor anticoagulation postangioplasty (PTCA), but may be unreliable. We assessed the accuracy of a new method we termed the ACT differential (ACT Diff), obtained by measuring the difference between an sHR ACT and a heparinase ACT from the same sample. Heparinase removes heparin from its sample and provides a current heparin-free baseline. For phase 1 of the study, the sHR ACT, ACT Diff, and laboratory APTT were measured in 250 samples from 75 PTCA patients. In 125 samples with an APTT prolonged but within measurement range, linear regression against the APTT was performed. The correlation coefficient was 0.74 for the ACT Diff and 0.24 for the sHR ACT. An ACT Diff of 15-25 sec was found to equal an APTT of 2.5-3.5 x control. In 50 samples with a normal activated partial thromboplastin time (APT), there was good differentiation by the ACT Diff of results from those adequately heparinized, with a value of 0.9 +/- 4.4 sec. The sHR ACT was 114 +/- 15.5 sec, and could not reliably distinguish between anticoagulated and nonanticoagulated samples. In 75 samples obtained with a high APTT (above measurement range), the ACT Diff was > 30 sec in 95% of samples, and again this allowed differentiation from therapeutic samples. The equivalent sHR ACT was 148 sec, and could not reliably distinguish between anticoagulated and overanticoagulated samples as the ACT Diff could. In phase 2, to examine the clinical usefulness of the ACT Diff, 286 patients were managed post-PTCA by starting heparin when ACT Diff fell to < 50 sec, maintaining ACT Diff at 15-25 sec during heparin infusions, and following cessation of heparin, by removing sheaths when the ACT Diff was < 7 sec. These patients were compared to a control group of 250 patients. Major bleeding (5% vs. 0.5%, P < 0.005) and minor bleeding (30% vs. 13%, P < 0.001) were significantly reduced in the group managed using the ACT Diff. The reduction in bleeding was thought to be due to the rapid availability of reliable results. Abrupt closure was low in both groups (0% with ACT Diff vs. 0.8%). No other thrombotic events occurred. Following phases 1 and 2, the ACT Diff replaced the APTT in all PTCA patients at this institution. In the 18 mo from July 1993, 1,104 patients were managed this way. Incidence of major bleeding (0.2%), transfusion requirement (0.1%), false anneurysm (0.6%), and abrupt closure during heparin infusion (0.1%) remained low. In conclusion, the ACT Diff is more accurate than an sHR ACT, and its clinical use in PTCA patients is associated with a very low incidence of complications from anticoagulation. Its routine use should be considered by units unable to obtain rapid APTT results.

Adult↗
PubMed1994

A simultaneous electrocardiogram is important when electroencephalography is used in the evaluation of loss of consciousness.

This study examined the use of electroencephalograms (EEGs) in 2 groups of patients with loss of consciousness (LOC), and the importance of a simultaneous electrocardiogram (ECG). Each group consisted of 75 patients referred for EEG. Group 1 patients (LOC without an established cause) had no clear history of convulsive disorder, while group 2 patients (LOC secondary to epilepsy) did. In all patients, it was ascertained if any previous cardiac investigations had been performed. All patients had an EEG performed with a simultaneous ECG. In addition to reporting the EEG, the neurologist reviewed the ECG rhythm and QRS morphology from the strip recording in an attempt to use this as a cardiac screening test. A cardiologist with the availability of all strip recordings and a subsequent 12 lead ECG reviewed his findings. The ECG was classified as significantly abnormal (potentially capable of causing syncope) in 17% of group 1 patients and 5% of group 2. The neurologist, using the simultaneous ECG strip recording only, correctly identified 14 of the 17 significantly abnormal ECGs (84%) and 127 of the 133 normal cases. In most cases, this was the only ECG evaluation as the EEG was performed without any prior cardiac investigation in 53% of group 1 patients and 92% of group 2. In conclusion, the EEG was often used as an initial investigation in these patients with LOC. A simultaneous ECG strip enabled the neurologist to detect most patients with significantly abnormal ECGs or rhythm. This will allow appropriate early cardiac review of these patients.

Adolescent↗
PubMed1994

Modifying fluoroscopic views reduces operator radiation exposure during coronary angioplasty.

OBJECTIVES: This three-part study examined the feasibility of reducing operator radiation exposure during coronary angioplasty. BACKGROUND: As case loads and complexity increase, some cardiologists are receiving increasing radiation scatter doses. Techniques to reduce this are therefore becoming more important. METHODS: First, the determinants of the operator dose were assessed by measuring the differences in scatter dose with different camera views. The relative contribution of fluoroscopy as opposed to cine was then quantified. Finally, operators were provided with these data, and subsequent changes in technique were evaluated. RESULTS: Left anterior oblique views resulted in 2.6 to 6.1 times the operator dose of equivalently angled right anterior oblique views. Increasing steepness of the left anterior oblique view also resulted in a progressive increase in operator dose, with left anterior oblique 90 degrees causing eight times the dose of left anterior oblique 30 degrees and three times that of left anterior oblique 60 degrees. In the 45 coronary angioplasty cases prospectively analyzed, fluoroscopy was found to be a greater source of total radiation than cine by a 6.3:1 ratio (range 1.1 to 15.8). Once operators were made aware of the importance of left anterior oblique fluoroscopy, there was a marked reduction in its use. When this was not feasible, there was a reduction in the steepness of the angulation. Left anterior oblique fluoroscopy during angioplasty of the left anterior descending and circumflex coronary arteries was reduced from 40% of total screening time to approximately 5%, and left anterior oblique angulation for fluoroscopy during angioplasty of the right coronary artery decreased from 43.6 degrees (+/- 9.1 degrees) to 29.4 degrees (+/- 2.2 degrees). Success rates (90% vs. 89%) and screening times (19.5 vs. 20.7 min) remained unchanged in 200 coronary angioplasties performed after the study. Average operator radiation dose (measured by radiation badges worn under lead at waist level) was reduced from 32.6 to 14.3 microSv/operator per week despite a slight increase in case load. CONCLUSIONS: Fluoroscopy is the major source of total radiation exposure during coronary angioplasty, with left anterior oblique views providing the highest dose. Modification of views is feasible and will result in significant reduction of operator radiation dose.

Angioplasty, Balloon↗
PubMed1994

Short and long-term results of coronary angioplasty in patients over 75 years.

AIMS: This report reviews the outcome of percutaneous transluminal coronary angioplasty (PTCA) on patients aged 75 years or over at this institution, in order to provide statistics that may be useful in managing elderly patients. METHODS: All elderly patients undergoing PTCA between January 1984 and December 1990 were included. Data concerning the PTCA procedure and short term (hospital stay) outcome were compared to those of all patients less than 75 years who underwent PTCA during the same period. Long term outcome was obtained for all surviving elderly patients. RESULTS: One hundred and eleven procedures were performed on patients over 75 years, compared to 3183 procedures on patients under 75. The incidence of PTCA in the elderly increased to 6.7% of all procedures in 1990. Elderly patients were more symptomatic (97% vs 79% in patients under 75 years had Canadian Cardiovascular Society grade 3 or 4 angina), more frequently had the procedure performed urgently (39% vs 14%) and often (67%) had risk factors for PTCA (3 vessel disease, significant left ventricular dysfunction, or a complicating medical illness). Primary success rates (86% vs 90% in patients under 75 years), urgent coronary artery bypass grafting (1.8% vs 1.9%) and Q wave infarction (1.8% vs 1.0%) were similar in the two age groups. In the elderly, procedural difficulties requiring non standard equipment were common (61%), and in-hospital mortality was increased (4.5% vs 0.7%). Additionally, three patients died after discharge resulting in a 30 day mortality of 7.2%. A favourable long term outcome was obtained in 50% of patients at a mean follow up of 20 months. Unfavourable or neutral outcome was due to one or more of the following; death (16%), coronary artery bypass grafting (19%), acute myocardial infarction (7.5%) or significant residual angina (17%). CONCLUSIONS: Highly symptomatic patients over 75 years constitute a high risk group for PTCA, with approximately half obtaining a favourable long term outcome.

Age Factors↗
PubMed1993

Undesirable mode switching with a dual chamber rate responsive pacemaker.

The Telectronics 1250 Meta MV DDDR pacemaker is a new device featuring automatic mode switching from DDDR to VVIR pacing in the event of an atrial arrhythmia. Although mode switching is a valuable feature, sinus tachycardia can cause an undesirable mode switch to occur. Of 24 implants at this institution, 11 have been for an AV conduction disorder. Eight of these 11 patients were specifically evaluated for undesirable mode switching. During exercise testing and/or Holter monitoring, mode switching was repeatedly seen in seven of the eight at low levels of exercise. Factors precipitating mode switching were a low rate response factor, low upper rate setting, long base postventricular atrial refractory period (PVARP) and a long AV delay. During Holter monitoring, patients spent up to 50% of the time in VVIR pacing as opposed to DDDR pacing. It is concluded that patients with intact sinus node function are at risk of undesirable mode switching and should probably be programmed to the DDD mode unless there is a specific indication for DDDR pacing. If the DDDR mode is chosen, careful selection of the aforementioned pacing parameters is required.

Adult↗
PubMed1992

Use of twenty-four hour infusions of intracoronary tissue plasminogen activator to increase the application of coronary angioplasty.

Coronary arteries occluded by long lengths of thrombus are usually considered unattractive for angioplasty. Nine patients (8 male, mean age 50.1 years) undergoing angiography for unstable angina were found to have single vessel disease considered unsuitable for angioplasty as the vessel was occluded by a long length of thrombus. These patients were treated with 24 hr intracoronary infusions of 100 mg tPA in an attempt to make angioplasty feasible. Marked thrombolysis occurred in 7 patients who received uncomplicated infusions. One case was unsuccessful due to catheter displacement, while another had the infusion ceased due to an intracerebral bleed from a previously silent A-V malformation. This was the only major complication. Angioplasty was attempted in 6 of 7 cases where lysis had been achieved, with success in all lesions attempted. This reports shows that intracoronary tPA infused over prolonged periods produces excellent thrombolysis, making angioplasty feasible in some patients who were previously unsuitable.

Angina, Unstable↗
PubMed1992

Radiofrequency catheter ablation of the AV node to improve the function of an antitachycardia implantable defibrillator.

A case of coexisting atrial fibrillation and ventricular tachycardia in a patient with an implantable cardioverter defibrillator is described. Despite careful reprogramming, the device was not always able to distinguish between the two arrhythmias and continued to deliver inappropriate antitachycardia therapy including DC shocks. Attempts to pharmacologically control the atrial fibrillation were unsuccessful so radiofrequency ablation of the atrioventricular node was performed. Following successful ablation, there have been no further false detections no episodes of further ventricular tachycardia.

Aged↗