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Biomedical subjects

L M Shapiro

Publications and source records attributed to L M Shapiro.

At least 37 records · Page 2Linked to original sources
PubMed1998

Coronary angiography from the radial artery--experience, complications and limitations.

AIMS: to assess the outcomes, complications and limitations of coronary angiography performed via percutaneous radial artery puncture. METHODS AND RESULTS: two hundred and fifty patients underwent diagnostic coronary angiography from the radial artery, 182 (72.8%) of whom had contraindications to the femoral approach, for example due to peripheral vascular disease (n=85), therapeutic anticoagulation (29), or failed femoral approach (17). Procedural success in this high-risk population was achieved in 231 patients (92.4%). Principle reasons for failure were unsuccessful radial access (5) and arterial spasm (5). Procedure duration (SD) for an operator's first 20 cases compared with cases thereafter (min) was 47.7 (16.7) vs. 41.5 (14.6), P=0.0004; fluoroscopy time (min) 9.7 (7.1) vs. 6.6 (5.1), P=0.0001 and procedural success 89.6% vs. 94.1%, P=ns. Complications included two deaths associated temporally with catheterisation, three cases of arterial dissection without ischaemic sequelae and one transient ischaemic attack. CONCLUSIONS: coronary angiography can be performed successfully from the radial artery, but this approach has limitations, which include the need to demonstrate dual palmar vascular supply, the prolonged learning phase, the procedural failure rate, patient discomfort and a demonstrable incidence of vascular and haemodynamic complications. We believe that radial coronary angiography should only be undertaken when there is a contraindication to the femoral approach.

Chi-Square Distribution↗
PubMed1998

Comparison of radial versus brachial approaches for diagnostic coronary angiography when the femoral approach is contraindicated.

One hundred patients with contraindications to the femoral approach were randomized to undergo diagnostic coronary angiography via percutaneous radial puncture or brachial artery cutdown. Procedure duration, fluoroscopy time, and total radiation dose were significantly less via the radial route, whereas procedural success, complication rates, and pain scores were comparable; we conclude that the radial technique should be the arm approach of choice for new trainees, although there will be occasions when radial access fails and a brachial approach is required.

Aged↗
PubMed1998

Balloon mitral valvuloplasty employing double transseptal puncture.

Patients with mechanical aortic valve prostheses occasionally develop subsequent mitral stenosis and present as candidates for further intervention. Repeat thoracotomy in such patients carries considerable operative risk, but the traditional alternative of balloon mitral valvuloplasty with transaortic intraventricular monitoring is not feasible because mechanical aortic prostheses cannot be safely crossed at catheterization. We have therefore developed a technique for performing the procedure via double transseptal puncture. We present the technique and our experience of its use in four patients with mechanical aortic prostheses presenting for balloon mitral valvuloplasty.

Aged↗
PubMed1998

Conservative operation for infective endocarditis of the mitral valve.

BACKGROUND: Subvalvular preservation is necessary to maintain left ventricular function, but accidental retention of infected tissue could cause postoperative endocarditis. METHODS: We examined 71 consecutive patients who underwent operation for mitral endocarditis. Endocarditis was uncontrolled and active in 24 patients, partially treated (unfinished antibiotic course) in 17, and healed in 30. RESULTS: Valves were repaired in 17% versus 59% versus 63% and replaced with subvalvular preservation in 25% versus 6% versus 3% of the uncontrolled active, partially treated, and healed groups, respectively. Thirty-day mortality was 29% versus 0% versus 3.3% (p=0.003), total mortality was 46% versus 18% versus 17% (p=0.035), and complications-related mortality was 38% versus 11% versus 13% (p=0.054), respectively. There was a trend toward lower complications-related mortality with subvalvular preservation than without. Postoperative endocarditis occurred in 3 of 30 patients without and 1 of 41 patients with subvalvular preservation. CONCLUSIONS: Postoperative mortality in uncontrolled active mitral endocarditis remains high, but results are good with partially treated or healed endocarditis. Subvalvular preservation improves outcome, does not increase postoperative endocarditis rates, and should be performed whenever feasible.

Anti-Bacterial Agents↗
PubMed1998

Transthoracic echocardiographic measurement of coronary artery diameter: validation against quantitative coronary angiography.

There has been no in vivo validation of the use of transthoracic echocardiography to measure distal left anterior descending coronary artery (LAD) diameter. We therefore undertook transthoracic echocardiography on 65 male patients immediately before cardiac catheterization to compare echocardiographic and angiographic findings. The distal LAD was successfully imaged in 41 (63%) patients; 29 of these had an angiographically normal distal LAD as assessed by an independent cardiologist and formed the study group. Transthoracic echocardiographic and quantitative coronary angiographic measurements of distal LAD diameter were made. Echocardiographic measurements ranged from 0.14 to 0.28 cm (mean 0.20 cm). Angiographic results ranged from 0.12 to 0.28 cm (mean 0.195 cm). Correlation between techniques was good (r=.925). The maximum discrepancy between transthoracic echocardiography and quantitative coronary angiography was 0.03 cm. Limits of agreement were +0.032 to -0.024 cm. We conclude that transthoracic echocardiography is a valid technique for measurement of distal LAD diameter.

Cardiac Catheterization↗
PubMed1998

Noninvasive analysis of coronary artery poststenotic flow characteristics by using transthoracic echocardiography.

This study was performed (1) to test whether transthoracic echocardiography may detect coronary flow velocity in the left anterior descending coronary artery distal to stenoses; and (2) to noninvasively assess coronary artery hemodynamics distal to coronary artery stenoses. High-frequency transthoracic echocardiography was used to assess blood velocity patterns in the distal segment of the left anterior descending coronary artery of 128 consecutive patients (mean age, 58 +/- 9 years; 97 men and 31 women) who underwent cardiac catheterization for investigation of angina. Biphasic, diastolic predominant Doppler velocity patterns were obtained in 67 patients (52%). There was no significant difference in any measurements of systolic blood velocity between patients with unobstructed (less than 30% stenosis) left anterior descending coronary artery, moderate stenosis (30% to 70% obstruction), or severe stenosis (more than 70% obstruction). Patients with severe stenosis demonstrated a reduction in the diastolic component of blood flow velocity in the distal left anterior descending coronary artery compared with patients in the other two groups. This technique may be useful for the noninvasive assessment of the significance of stenotic left anterior descending coronary artery disease or the outcome of interventional procedures.

Blood Flow Velocity↗
PubMed1998

Ventricular pacemaker upgrade: experience, complications and recommendations.

OBJECTIVE: To assess outcomes of pacemaker upgrade from single chamber ventricular to dual chamber. DESIGN: Retrospective analysis of patients undergoing the procedure. SETTING: Specialist cardiothoracic unit. PATIENTS: 44 patients (15 female, 29 male), mean (SD) age at upgrade 68.2 (12.9) years. INTERVENTIONS: Upgrade of single chamber ventricular to dual chamber pacemaker. MAIN OUTCOME MEASURES: Procedure duration and complications. RESULTS: Principal indications for upgrade were pacemaker syndrome (17), "opportunistic"--that is, at elective generator replacement (8), heart failure (7), non-specific breathlessness/fatigue (7), and neurally mediated syncope (3). Mean (SD) upgrade procedure duration (82.9 (32.6) minutes) significantly exceeded mean VVI implantation duration (42.9 (13.3) minutes) and mean DDD implantation duration (56.6 (22.7) minutes) (both p < 0.01). Complications included pneumothorax (1), ventricular arrhythmia requiring cardioversion (2), protracted procedure (10), atrial lead repositioning within six weeks (8), haematoma evacuation (1), superficial infection (1), and admission to hospital with chest pain (1); 20 patients (45%) suffered one or more complications including four of the eight who underwent opportunistic upgrade. CONCLUSIONS: Pacemaker upgrade takes longer and has a higher complication rate than either single or dual chamber pacemaker implantation. This suggests that the procedure should be performed by an experienced operator, and should be undertaken only if a firm indication exists. Patients with atrial activity should not be offered single chamber ventricular systems in the belief that the unit can be upgraded later if necessary at minimal risk.

Aged↗
PubMed1998

Late complications following permanent pacemaker implantation or elective unit replacement.

OBJECTIVE: To determine the rate of late complications following first implantation or elective unit replacement of a permanent pacemaker system. DESIGN: Analysis of pacemaker data and complications prospectively acquired on a computerised database. Complications were studied over an 11 year period from January 1984 to December 1994. SETTING: Tertiary referral cardiothoracic centre. PATIENTS: Records of 2621 patients were analysed retrospectively. MAIN OUTCOME MEASURES: Complications requiring repeat procedures occurring more than six weeks after pacemaker implantation or elective unit replacement. RESULTS: The overall rate of late complications was significantly lower after first implantation of a permanent pacemaker (34 cases, complication rate 1.4%, 95% confidence interval 0.9% to 1.9%) than after elective unit replacement (16 cases, complication rate 6.5% (3.3% to 9.7%). There were 20 cases of erosion, 18 infections, five electrode problems, and seven miscellaneous problems. Complications were more common with inexperienced operators (18.9% (6.0% to 31.8%)) than with experienced operators (0.9% (0.3% to 1.5%). CONCLUSIONS: The incidence of late complications following pacemaker implantation is low and compares favourably with early complication rates. The majority are caused by erosion and infection. Patients who have undergone elective unit replacement are at particular risk.

Adult↗
PubMed1997

Analysis of phasic flow velocity dynamics in the left anterior descending coronary artery before and after angioplasty using transthoracic echocardiography in patients with stable angina pectoris.

High-frequency transthoracic Doppler echocardiography was used to determine the effects of significant stenosis on distal coronary blood flow velocity profiles. Before coronary angioplasty there was a reduction in diastolic and systolic flow and diastolic/systolic peak velocity ratio. After successful angioplasty velocity ratios returned to normal.

Aged↗
PubMed1997

Midterm results of mitral valve repair with the Sculptor annuloplasty ring.

BACKGROUND: The partly flexible Sculptor ring is more physiologic than the rigid Carpentier-Edwards ring and may improve outcome. METHODS: We studied 221 consecutive patients who underwent mitral valve repair for mitral regurgitation. The Sculptor ring was randomly implanted in 30 patients (Sculptor ring group) and the Carpentier-Edwards ring in 36 patients (Carpentier-Edwards ring control group) from 1993 to 1994. Before 1993, 155 patients received the Carpentier-Edwards ring (Carpentier-Edwards ring historical group). Baseline group characteristics were similar. RESULTS: Thirty-day mortality in the Sculptor ring, Carpentier-Edwards ring control, and Carpentier-Edwards ring historical groups was 0.0% versus 2.8% versus 3.2% (p = 0.61), respectively. At 18 months, survival was 86% +/- 6% versus 88% +/- 7% versus 90% +/- 3% (p = 0.89), and freedom from complications was 100% +/- 0% versus 100% +/- 0% versus 98% +/- 1% (p = 0.51) for endocarditis, 90% +/- 6% versus 94% +/- 4% versus 96% +/- 2% (p = 0.47) for severe mitral regurgitation, 93% +/- 5% versus 91% +/- 5% versus 92% +/- 2% (p = 0.91) for thromboembolism, and 77% +/- 8% versus 80% +/- 7% versus 82% +/- 3% (p = 0.49) for myocardial failure, respectively. CONCLUSIONS: The Sculptor ring is a safe alternative to the prosthetic annuloplasty rings in current use. The benefits of its physiologic design are either clinically insignificant or undetectable with a small sample size.

Aged↗
PubMed1997

The morphologic consequences of systemic training.

The development of echocardiography in the 1970s led to the flourishing of the study of the athlete's heart. From the earliest studies, it was apparent that athletes develop enlargement of the left ventricular cavity and thickening of myocardium in response to prolonged repetitive training. The changes in echocardiographic measurements are small and often within quoted normal ranges. By comparison to sedentary controls, however, left ventricular end-diastolic dimension is increased by approximately 10%, posterior wall dimension by 15% to 20%, and calculated mass by up to 45%.

Echocardiography↗
PubMed1997

Transthoracic echocardiographic measurement of coronary blood flow and reserve.

The objectives of this study were to evaluate the use of high-frequency (5 MHz) transthoracic echocardiography for the noninvasive measurement of coronary blood flow and to test its ability to detect small changes in blood flow that may accompany pharmacologic intervention. High-frequency (5 MHz) transthoracic echocardiography was performed on the distal segment of the left anterior descending coronary artery of 32 consecutive patients (23 men and nine women; mean age 60 +/- 10 years) before and after the administration of 0.4 mg sublingual nitroglycerin. The results were compared with those of 10 patients (eight men and two women; mean age 59 +/- 6 years) in whom the ungrafted left internal mammary artery was studied. Doppler velocity profiles of the left anterior descending coronary artery were detected in 18 (56%) of the 32 Study patients. Left anterior descending coronary artery diameter and blood flow were measured in 14 patients (44%). There was no significant difference in blood flow between the left anterior descending artery (74 +/- 35 ml/min) and the internal mammary artery (52 +/- 25 ml/min). After administration of nitroglycerin, there was a 24% decrease in coronary blood flow from 74 +/- 35 ml/min to 56 +/- 30 ml/min (p < 0.05). This study suggests that high frequency transthoracic echocardiography may allow noninvasive identification of the left anterior descending coronary artery and detection of small changes in blood flow that accompany pharmacologic and mechanical intervention.

Adult↗
PubMed1997

Superiority of mitral valve repair in surgery for degenerative mitral regurgitation.

OBJECTIVES: We aimed to assess the influence of type of operation on outcome in degenerative mitral regurgitation. METHODS: We compared outcomes in 278 consecutive patients who underwent mitral valve repair (167 patients), replacement with subvalvular preservation (22 patients) and without subvalvular preservation (89 patients) for degenerative mitral regurgitation. RESULTS: There was a trend towards lower mortality with repair and replacement with subvalvular preservation compared to replacement without subvalvular preservation. Thirty-day mortality was 1.2% vs 0.0% vs 4.7% (ns) respectively. Six-year survival was, respectively, 67.8 +/- 7.4% (P = 0.088) vs 80.8 +/- 11.0% (P = 0.25) vs 63.3 +/- 5.9% for all-cause death, 78.5 +/- 6.8% (P = 0.063) vs 95.5 +/- 4.4% (P = 0.092) vs 67.6 +/- 5.9% for all complication-related death and 80.5 +/- 6.9% (P = 0.076) vs 100.0 +/- 0.0% (P = 0.045) vs 72.8 +/- 5.8% for complication-related death due to myocardial failure. Multivariate analysis confirmed independent beneficial effects from repair compared to replacement without subvalvular preservation on complication-related death (hazard ratio 0.42, P = 0.010) and death from myocardial failure (hazard ratio 0.40, P = 0.014), and from repair compared to mechanical replacement on thromboembolism (hazard ratio 0.45, P = 0.029) and anticoagulation-related haemorrhage (hazard ratio 0.19, P = 0.026). CONCLUSIONS: Mitral valve repair is superior to replacement. The greatest survival advantage is in reduced mortality from myocardial failure. Repair should be the operation of choice for degenerative mitral regurgitation.

Aged↗
PubMed1997

A quantitative description of dynamic left ventricular geometry in anaesthetized rats using magnetic resonance imaging.

We report a functional application of magnetic resonance imaging (MRI) for the quantitative description of left ventricular geometry through systole and diastole in normal anaesthetized Wistar rats that might be applicable for the analysis of chronic changes resulting from pathological conditions. Images of cardiac anatomy were acquired through planes both parallel and perpendicular to the principal cardiac axis at times that were synchronized to the R wave of the electrocardiogram. The images of the transverse sections were assembled into three-dimensional representations of left ventricular geometry at consecutive time points through the cardiac cycle. This confirmed the geometrical coherence of the data sets, that each slice showed circular symmetry, and that the images were correctly aligned with the appropriate anatomical axes. Different models for the three-dimensional geometry of the left ventricle were then tested against the epi- and endocardial surfaces reconstructed from images of the transverse sections of the left ventricle in both systole and diastole using least-squares minimizations in three dimensions. In agreement with previous reports in the human heart, an elliptical figure of revolution offered an optimal fit to the epicardial and endocardial geometry for the rat heart in diastole. This was in preference to models that used spherical, quartic or parabolic geometries. However, in contrast to contraction in the human heart, all these geometrical representations broke down during systolic ejection in the rat heart. We therefore introduced a more general hybrid model which described left ventricular geometry in terms of the variation of the radii r(z), independently determined for each slice, with its position z along the principal cardiac axis. The resulting function r(z) could then be described by a simple ellipsoid of revolution not only during diastole, but also throughout ventricular ejection. The findings also ruled out alternative geometrical representations. It was then possible additionally to reconstruct the luminal and total left ventricular volumes, wall thicknesses and ejection fractions through the cardiac cycle and to confirm that the predicted total ventricular wall volume was conserved throughout the cardiac cycle. Our hybrid model of cardiac geometry may thus be useful for non-invasive serial studies of chronic pathological changes that use the rat as a model experimental system.

Animals↗
PubMed1997

Transthoracic Doppler echocardiographic analysis of phasic coronary blood flow velocity in hypertrophic cardiomyopathy.

OBJECTIVE: To use transthoracic Doppler echocardiography to assess coronary blood flow non-invasively in patients with hypertrophic cardiomyopathy. DESIGN: High frequency transthoracic Doppler echocardiography was used to assess resting phasic coronary velocity patterns in patients with hypertrophic cardiomyopathy and to define the relation between coronary flow patterns and clinical, echocardiographic, and haemodynamic manifestations of this condition. SETTING: A tertiary referral cardiothoracic centre. METHODS: Fifteen patients (10 men and five women, mean (SD) age 49 (10.3) years) with asymmetric hypertrophic cardiomyopathy underwent high frequency (5 MHz) transthoracic Doppler echocardiographic assessment of the left anterior descending coronary artery. In addition, standard two dimensional echocardiography was performed. The results were compared with 16 normal participants (nine men and seven women, mean age 61.2 (10.7) years) who had no evidence of cardiac disease. RESULTS: Biphasic diastolic predominant coronary artery blood velocity profiles were obtained in all patients and controls. Systolic peak blood velocity and velocity time integral were significantly reduced in the hypertrophic cardiomyopathy group compared with controls (11.3 (15.8) cm/s and 1.09 (1.78) cm v 20.5 (13.1) cm/s and 4.23 (2.80) cm, respectively, P < 0.05). A reversed pattern of systolic blood flow velocity was found in three patients with severe anterior wall and septal hypertrophy. During diastole there was prolongation of the diastolic acceleration (203 (53) ms v 110 (60) ms in controls, P < 0.05) and deceleration times (487 (200) ms v 210 (90) ms in controls, P < 0.05). There was no significant difference between those with and without symptoms or a left ventricular outflow tract gradient. CONCLUSIONS: Patients with hypertrophic cardiomyopathy have abnormal systolic and diastolic coronary flow profiles at rest when measured by transthoracic echocardiography.

Adult↗