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R A Nishimura

Publications and source records attributed to R A Nishimura.

At least 37 records · Page 2Linked to original sources
PubMed2000

Dual chamber pacing for patients with hypertrophic obstructive cardiomyopathy: a clinical perspective in 2000.

In some patients with hypertrophic cardiomyopathy, the dynamic left ventricular outflow tract obstructive gradient results in exercise-limiting symptoms of dyspnea, angina, and syncope. Dual chamber pacing has been proposed as a widely available alternative treatment for a subset of patients with symptomatic hypertrophic obstructive cardiomyopathy. Initial studies showed a reduction in gradient and an improvement in symptoms in almost 90% of patients with severe symptoms. We report the Mayo Clinic experience with dual chamber pacing in 38 patients with hypertrophic obstructive cardiomyopathy who had permanent pacemakers implanted for limiting symptoms intractable to medical therapy. After a mean +/- SD follow-up of 24 +/- 14 months, subjective improvement was reported in 47% of patients. However, there was no statistical difference between the maximal oxygen consumption at last follow-up and AAI pacing (atrial sensing and atrial pacing) (18.6 +/- 1.1 mL.kg-1.min-1) (i.e., when the pacemaker was implanted but not pacing continuously). This article discusses the clinical perspective on the utility of dual chamber pacing for patients with hypertrophic obstructive cardiomyopathy.

Adult↗
PubMed2000

Idiopathic annular dilation: a rare cause of isolated severe tricuspid regurgitation.

The management of patients with severe tricuspid regurgitation (TR) requires the clinician to clarify the mechanism of regurgitation. Primary disorders of the tricuspid valve, either congenital or acquired, may be readily identified by echocardiography. Severe TR most often results from left-sided heart disease and secondary pulmonary hypertension. Cardiomyopathic processes may also cause right ventricular failure and functional TR. We report three patients with severe TR due to idiopathic annular dilation. The tricuspid valves were otherwise normal on surgical inspection, and the pulmonary pressures were not significantly elevated. Each patient was aged over 65 years and had chronic atrial fibrillation with preserved left ventricular systolic function. Surgical treatment was associated with marked clinical improvement. Clinicians should recognize this unusual but treatable cause of right-sided congestive heart failure.

Aged↗
PubMed1999

Comparison of long-term results of percutaneous mitral balloon valvotomy with closed transventricular mitral commissurotomy at a single North American Institution.

Long-term (>3 years) follow-up data were obtained from 102 consecutive patients undergoing percutaneous mitral balloon valvotomy (PMBV). Data were collected prospectively by review of the medical record, mailed questionnaire, and/or telephone. Data on patients with closed mitral commissurotomy (CMC) at our institution have been previously reported and serve as the comparison group. Follow-up data was 98% complete at a mean of 57 months for PMBV patients. Compared with patients undergoing CMC, these patients were older (54+/-14 vs 43.6+/-10 years, p <0.001) and more likely to have undergone previous mitral valve surgery (17% vs 4%, p <0.001). The observed 5-year survival in the PMBV group was no different from that observed in the CMC group (83% vs 90%, p = NS) or from that predicted by the model developed from the CMC patients. Commissural calcium was associated with death and death or repeat mitral valve procedure in the multivariate analysis. Long-term survival free from repeat procedures was equivalent when patients with commissural calcium were excluded. Thus, PMBV offers long-term survival and freedom from subsequent mitral valve procedures similar to CMC.

Adult↗
PubMed1999

Assessment of permanent dual-chamber pacing as a treatment for drug-refractory symptomatic patients with obstructive hypertrophic cardiomyopathy. A randomized, double-blind, crossover study (M-PATHY).

BACKGROUND: Dual-chamber pacing (DDD) has been proposed as a treatment alternative to surgery for severely symptomatic patients with obstructive hypertrophic cardiomyopathy (HCM), based largely on uncontrolled studies. METHODS AND RESULTS: This prospective, multicenter trial assessed pacing in 48 symptomatic HCM patients with >/=50 mm Hg basal gradient, refractory to drug therapy. Patients were randomized to 3 months each of DDD pacing and pacing backup (AAI-30) in a double-blind, crossover study design, followed by an uncontrolled and unblinded 6-month pacing trial. With randomization, no significant differences were evident between pacing and no pacing for subjective or objective measures of symptoms or exercise capacity, including NYHA functional class, quality of life score, treadmill exercise time or peak oxygen consumption. After 6 additional months of unblinded pacing, functional class and quality of life score were improved compared with baseline (P<0.01), but peak oxygen consumption was unchanged. Outflow gradient decreased 40%, 82+/-32 mm Hg to 48+/-32 mm Hg (P<0. 001), and was reduced in 57% of patients but showed no change or an increase in 43%. At 12 months, 6 individual patients (12%) showed improved functional capacity; each was 65 to 75 years of age. Left ventricular wall thicknesses in the overall study group showed no remodeling between baseline (22+/-5 mm) and 12 months (21+/-5 mm; P=NS). CONCLUSIONS: (1) Pacing cannot be regarded as a primary treatment for obstructive HCM; (2) with randomization, perceived symptomatic improvement was most consistent with a substantial placebo effect; (3) longer, uncontrolled pacing periods were associated with some subjective benefit but unaccompanied by objective improvement in cardiovascular performance and should be interpreted cautiously; (4) modest reduction in outflow gradient was achieved in most patients; and (5) a small subset (12%) >/= 65 years of age showed a clinical response, suggesting that DDD pacing could be a therapeutic option for some elderly patients.

Adult↗
PubMed1999

Carcinoid heart disease and carcinoid syndrome: successful surgical treatment.

Tumor debulking can greatly improve quality of life for patients with malignant carcinoid syndrome, but hepatic cytoreduction is confounded by carcinoid heart disease, which can cause postsinusoidal portal hypertension, thereby increasing the risk of death from hemorrhage during hepatic resection. We describe a patient with metastatic carcinoid syndrome and carcinoid heart disease who had repair of his carcinoid heart disease and, after improvement of right-sided heart function, had successful hepatic debulking of carcinoid metastases.

Adult↗
PubMed1999

Fixed left ventricular outflow tract obstruction in presumed hypertrophic obstructive cardiomyopathy: implications for therapy.

BACKGROUND: A subset of patients presenting with a presumed diagnosis of hypertrophic obstructive cardiomyopathy (HOCM) have a fixed left ventricular outflow tract (LVOT) obstruction. Recognition of this pathophysiologic abnormality is important in choosing therapy. METHODS: Of patients referred for treatment of HOCM, 4 had fixed LVOT obstruction. Clinical and echocardiographic data and surgical findings were reviewed. RESULTS: In the 4 patients with clinical features consistent with HOCM or HOCM-like conditions, echocardiography showed fixed LVOT obstruction with an early-peaking LVOT Doppler signal or absence of severe systolic anterior motion of the mitral valve. The causes of fixed obstruction included accessory mitral tissue with associated fibrous ring (1 patient), fixed subaortic tunnel stenosis (2 patients), and a discreet subaortic ridge (1 patient). After surgical relief of the fixed LVOT obstruction, all patients had relief of the ventricular outflow tract gradient. CONCLUSIONS: Not all patients with a presumed diagnosis of HOCM have isolated dynamic LVOT obstruction but may have isolated or additional fixed obstruction. Careful two-dimensional and Doppler echocardiography are needed to identify this subset of patients who are best treated surgically.

Adult↗
PubMed1999

Comparison of dual-chamber pacing versus septal myectomy for the treatment of patients with hypertrophic obstructive cardiomyopathy: a comparison of objective hemodynamic and exercise end points.

OBJECTIVES: The purpose of this study was to compare the treatment effects of septal myectomy with dual-chamber pacing in patients with hypertrophic obstructive cardiomyopathy (HOCM). BACKGROUND: The optimal treatment for symptomatic patients with drug-refractory HOCM is unknown. Both dual-chamber pacing and surgical myectomy may result in subjective symptom improvement. However, no direct comparisons with objective end points have been reported. METHODS: Thirty-nine patients with symptomatic HOCM were analyzed in this concurrent cohort study. Twenty patients underwent surgical myectomy, and 19 received dual-chamber pacemakers based on patient preference. These patients had prospective baseline and follow-up evaluations including physician assessment, echocardiography and standardized metabolic treadmill exercise testing. RESULTS: Baseline symptom status, left ventricular outflow tract gradients, exercise times and maximal oxygen consumption peak were similar between the two groups. Left ventricular outflow gradient was reduced from 76+/-57 to 9+/-17 mm Hg (p = 0.0001) after myectomy, and from 77+/-61 to 55+/-39 mm Hg (p = 0.07) after pacing (p = 0.02 for comparison with myectomy). Ninety percent of myectomy patients experienced symptomatic improvement as compared with 47% in the pacing group. Exercise duration increased significantly from 6.6+/-2.8 to 8.7+/-3.0 min (p = 0.0003) after myectomy compared with a change from 6.4+/-2.1 to 7.0+/-2.2 min (p = NS) in the pacing group. Maximal oxygen consumption increased from 19.4+/-6.4 to 22.2+/-6.5 ml/kg/min after myectomy (p = 0.004), whereas the pacing group did not experience any significant change (19.6+/-6.5 vs. 20.1+/-6.5 ml/kg/min, p = NS). CONCLUSIONS: Surgical myectomy and dual-chamber pacing improve subjective measures of functional status in patients with symptomatic HOCM. In this nonrandomized study, myectomy offered greater reduction in left ventricular outflow tract gradients and larger improvements in objective measures of patient symptoms and functional status when compared with dual-chamber pacing.

Aged↗
PubMed1999

Isolated tricuspid valve surgery for severe tricuspid regurgitation following prior left heart valve surgery: analysis of outcome in 34 patients.

BACKGROUND AND AIMS OF THE STUDY: Patients with symptoms of right heart failure due to severe tricuspid regurgitation following a prior operation on left heart valves present a difficult problem. The outcome of tricuspid surgery in this setting is not well defined. We describe a single-center experience of isolated tricuspid valve surgery after prior left heart valve surgery, and analyze potential risk factors for a poor outcome. METHODS: Thirty-four patients who underwent isolated tricuspid valve operation for severe tricuspid regurgitation following prior valvular surgery for left-sided valve disease between 1980 and 1997 were identified. Charts were reviewed for clinical, echocardiographic, catheterization and surgical data. Follow up of survivors was conducted by telephone to ascertain functional status. RESULTS: Three patients died in hospital (early mortality rate, 8.8%). At a follow up of 71 +/- 39 months, 13 patients were alive and 21 reached an end-point (three cardiac reoperations, 18 deaths). Event-free actuarial survival at five years was 41.6 +/- 9.2%. Patients who were alive at follow up had a mean NYHA functional class of 2.1 +/- 0.6 compared with 3.4 +/- 0.5 preoperatively; 85% of survivors were symptomatically improved. Predictors of poor outcome were: increased age at the time of tricuspid surgery (p = 0.0007) and higher number of prior cardiac operations (one versus two or three, p-value 0.01, relative risk 3.4). Pulmonary artery systolic pressure, left ventricular ejection fraction, right ventricular function and size, annulus diameter, tricuspid valve pathology, and valve replacement versus repair were not predictive of outcome. CONCLUSIONS: Isolated tricuspid valve surgery for severe tricuspid regurgitation following prior surgery for left-sided heart valve disease can be performed with acceptable early mortality. There remains a high late mortality that is predicted only by age and the number of previous cardiac operations. However, in this selected group of severely symptomatic patients, significant improvement in symptoms are achieved in the survivors.

Adolescent↗
PubMed1998

Pitfalls in clinical recognition and a novel operative approach for hypertrophic cardiomyopathy with severe outflow obstruction due to anomalous papillary muscle.

BACKGROUND: Ventricular septal myotomy/myectomy (Morrow procedure) is the standard surgical option for severely symptomatic patients with hypertrophic cardiomyopathy (HCM) and marked basal obstruction to left ventricular outflow due to mitral valve systolic anterior motion. In some patients, however, congenital malformations of the mitral apparatus may be responsible for outflow obstruction; the failure to recognize this morphology before operation could have adverse consequences. METHODS AND RESULTS: We recently evaluated 2 patients with obstructive HCM operated on at Mayo Medical Center in 1997 who demonstrated direct anomalous papillary muscle insertion into the anterior mitral leaflet, producing muscular midcavity obstruction. This anomaly is potentially identifiable with echocardiography by exaggerated anterior displacement of hypertrophied papillary muscles within the left ventricular cavity and the direct continuity between papillary muscle and anterior leaflet associated with a rigid motion pattern of the mitral apparatus. Echocardiographic diagnosis, however, was confused in both patients by the association of systolic anterior motion of the mitral valve, probably produced by freely mobile margins of the mitral leaflet unencumbered by papillary muscle insertion, and in 1 patient probably representing a second and more basal level of obstruction. Because outflow tract morphology was judged unsuitable for conventional myotomy/myectomy, a novel surgical strategy was designed to remove the outflow gradient in which an extensive myectomy trough (wider at its apical than basal extent) was created within the ventricular septum to papillary muscle level; also, in 1 patient, attachment of anterolateral papillary muscle with the lateral free wall was partially severed to increase mobility of the mitral apparatus. After surgery, both patients reported substantial relief of symptoms and improved exercise tolerance and also showed reduced or abolished basal outflow obstruction. CONCLUSIONS: In HCM, outflow obstruction due to anomalous papillary muscle insertion directly into anterior mitral leaflet is challenging to identify but should always be contemplated before operative intervention. This important (but often unsuspected) congenital malformation may require alternative surgical strategies to standard myotomy/myectomy, similar to those described here.

Adolescent↗
PubMed1998

Coronary vascular remodeling in association with endothelial dysfunction.

Vascular remodeling has been demonstrated in advanced and early coronary artery disease. Whereas the endothelium may play a role in the adaptive process of vascular remodeling, it is not known if this process occurs in association with changes in coronary blood flow reserve. Early coronary atherosclerosis is characterized by endothelial dysfunction which is manifested by an abnormal coronary blood flow in response to the endothelium-dependent vasodilator acetylcholine. This study was designed to test the hypothesis that coronary vascular remodeling occurs in association with coronary endothelial dysfunction early in the development of coronary atherosclerosis. Thirty-six patients found to have normal coronary angiograms or mild coronary artery disease were studied. Acetylcholine was infused into the left anterior descending artery. Patients were divided into 2 groups based on their coronary blood flow response to acetylcholine. Intravascular ultrasound measurements of the proximal left anterior descending diameter and area were obtained. Vessel diameter and area were measured at the external elastic membrane and indexed to body surface area. Vessel diameter and area were greater in patients with abnormal than normal responses to acetylcholine (5.2 +/- 0.3 mm and 19.5 +/- 0.9 mm2 vs 3.9 +/- 0.3 mm and 12.3 +/- 1.0 mm2; p <0.02, respectively). This difference persisted when measurements were indexed to body surface area. The current study suggests in vivo in humans that coronary vascular remodeling characterized by enlargement of the proximal coronary arteries occurs in association with endothelial dysfunction early in the course of coronary artery disease.

Adult↗
PubMed1998

Summary of the Mayo Clinic experience with direct left ventricular puncture.

Hemodynamic assessment of patients with prosthetic valves can be challenging. Noninvasive techniques may be limited by interference from the prosthetic material, whereas access to the left ventricle for direct pressure measurements often is not possible using common methods. The technique of direct, percutaneous left ventricular puncture has been proven to be a safe method that often provides needed data to help manage difficult clinical situations. We report our 8-yr experience with this technique for assessment of patients with valvular prostheses. Direct left ventricular puncture is a safe technique in patients with prior cardiac surgery and provided significant diagnostic information in the set of patients with multiple valvular prostheses.

Aortic Valve↗
PubMed1998

Echocardiography in the invasive laboratory: utility of two-dimensional echocardiography in performing transseptal catheterization.

OBJECTIVE: To evaluate the potential utility of transthoracic two-dimensional echocardiography as an aid in the technique of transseptal catheterization. DESIGN: We performed a prospective study of 58 patients (29 men and 29 women; mean age, 64.2 years) referred for cardiac catheterization, in whom a systematic approach was used with selective application of two-dimensional echocardiography. MATERIAL AND METHODS: The study group of 58 patients had the following diagnoses: mitral stenosis in 17, hypertrophic cardiomyopathy in 13, dilated cardiomyopathy in 13, aortic stenosis in 13, and prosthetic valve dysfunction and pulmonary hypertension in 1 each. With use of only fluoroscopic guidance, initial gentle pressure on the dilator alone was attempted for left atrial access. If the catheter resisted entry into the left atrium, two-dimensional echocardiography was performed to assess the catheter's position relative to the atrial septum, and adjustments were made accordingly. Transseptal puncture with a Brockenbrough needle was performed only after confirmation of the catheter position at the region of the fossa ovalis with two-dimensional echocardiography. RESULTS: The catheterization procedure was performed without complication in all 58 patients; the mean time to catheter placement was 5.6 +/- 3.5 minutes (range, 3 to 20). Two-dimensional echocardiography was used in 33 patients (57%) when left atrial access was not obtained. On the basis of echocardiographic images, the transseptal catheter had to be repositioned in 16 of these 33 patients (48%). CONCLUSION: Two-dimensional echocardiography offers value in demonstrating catheter position during transseptal catheterization and may be used in some patients to ensure transseptal puncture at the region of the fossa ovalis.

Adult↗
PubMed1998

Modern management of prosthetic valve anticoagulation.

Prosthetic heart valves have been effectively used for many years. Nonetheless, they are associated with risks of thrombosis and thromboembolic events, as well as anticoagulation-induced bleeding. Substantial changes in anticoagulation measurement and dosing have occurred during the past several years. In this review, the rationale for anticoagulation in patients with prosthetic heart valves, the changes in monitoring and dosing, and the comparison of relevant anticoagulation trials are discussed. On the basis of the existing data, new recommendations regarding lower anticoagulation levels are offered, utilizing a single value goal rather than the traditional therapeutic range. Perioperative management of anticoagulation is discussed in light of the available literature, and major drug interactions are reviewed.

Anticoagulants↗
PubMed1998

Newer advances in the diagnosis and treatment of mitral stenosis.

There have been significant changes in presentation, diagnosis, and therapy of patients with mitral stenosis. Both the prevalence of mitral stenosis, as well as the type of patient now with mitral stenosis, have changed significantly over the past few decades. In patients with mitral stenosis two-dimensional and Doppler echocardiography have become the diagnostic modalities of choice. The advent of percutaneous mitral balloon valvotomy now provides a nonsurgical approach for the treatment of selected patients with mitral stenosis.

Blood Flow Velocity↗
PubMed1998

Clinical assessment and management of mitral stenosis.

There have been significant advances in the diagnosis and treatment of the patient with mitral stenosis over the past two decades. Two-dimensional and Doppler echocardiography have supplanted the cardiac catheterization laboratory in the diagnosis and determination of the hemodynamic severity of the stenotic mitral valve. The development of a catheter-based approach for splitting fused commissures has led to earlier indications for intervention. It is likely that with the resurgence of rheumatic fever as well as influx of immigrant populations, the incidence of mitral stenosis may increase in the twenty-first century. It is thus important for the clinician to have a complete understanding of the evaluation and treatment options for the patient with mitral stenosis in the modern-day era.

Blood Flow Velocity↗