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Biomedical subjects

Rick A Nishimura

Publications and source records attributed to Rick A Nishimura.

At least 37 records · Page 2Linked to original sources
PubMed2004

The case for surgery in obstructive hypertrophic cardiomyopathy.

Relief of left ventricular (LV) outflow obstruction in patients with hypertrophic cardiomyopathy (HCM) and disabling symptoms refractory to maximum medical management has historically been a surgical problem. Surgical septal myectomy permanently abolishes systolic anterior motion of the mitral valve and mitral regurgitation, while normalizing LV pressures and wall stress. Also, these salutary goals are achieved without encumbering patients with post-procedural devices (e.g., pacemakers or defibrillators) or creating potentially arrhythmogenic substrates, as may occur with alcohol septal ablation. Procedural morbidity and mortality risk with myectomy is similar to, and in some institutions less than those for alcohol septal ablation. Over four decades, reports from numerous centers worldwide have consistently and unequivocably documented the benefits of surgery on hemodynamic and functional state, restoring normal and acceptable quality of life to patients of all ages by largely reversing the complications of heart failure. Long-term survival after myectomy is similar to that of the general population and superior to non-operated patients with obstruction. The LV outflow tract morphology in HCM is heterogeneous and not uncommonly includes congenital anomalies of the mitral valve apparatus for which the surgeon has the flexibility to adapt the repair, often employing an extended myectomy. In the current atmosphere of increasing and perhaps excessive enthusiasm for newer catheter-based interventions, it is a critical time to promote and re-emphasize that surgery is the time-honored (and presently the most effective) treatment strategy for relieving heart failure-related disability resulting from dynamic LV outflow obstruction in HCM, and is the primary treatment option for this subgroup of severely symptomatic drug-refractory patients.

Cardiomyopathy, Hypertrophic↗
PubMed2004

Coronary hemodynamics in patients with symptomatic hypertrophic cardiomyopathy.

The purpose of this study was to analyze coronary hemodynamics and determine a possible mechanism for microvascular dysfunction in patients with symptomatic hypertrophic cardiomyopathy (HC). Although patients with HC have been shown to have microvascular dysfunction and reduced coronary flow reserve (CFR), the mechanism by which this occurs is not well understood. We studied coronary hemodynamics in 8 patients with symptomatic HC and compared them with 8 matched controls. Compared with controls, patients with HC had higher coronary blood flow, lower coronary resistance, and lower CFR. Patients with HC also had abnormal phasic coronary flow characteristics. These results suggest that the reduction of CFR in patients with HC may be secondary to near maximal vasodilation of the microcirculation in the basal state.

Adult↗
PubMed2004

Septal myectomy results in regression of left ventricular hypertrophy in patients with hypertrophic obstructive cardiomyopathy.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is a genetic disorder characterized by ventricular hypertrophy that occurs in the absence of predisposing cardiovascular stimuli; approximately one quarter of patients with HCM will have left ventricular (LV) outflow tract obstruction. Transaortic septal myectomy relieves outflow gradients and improves symptoms, but the effect of operation on ventricular hypertrophy is not well defined. METHODS: We reviewed 60 patients who underwent septal myectomy for obstructive HCM; all had complete two-dimensional and Doppler studies including calculation of LV mass and LV mass index before operation and after dismissal. RESULTS: Before myectomy the mean LV outflow gradient was 67 +/- 44 mm Hg, and at dismissal the mean LV outflow gradient was 12 +/- 13 mm Hg (p < 0.004). We found a significant decrease in the LV mass and LV mass index that occurred early after operation and persisted beyond 2 years follow-up. The early decrease in LV mass was greatest in patients younger than 50 years, but patients of all ages benefited from extended septal myectomy with decrease in LV hypertrophy. CONCLUSIONS: Transaortic septal myectomy results in significant decreases in LV mass and LV mass index. This favorable remodeling occurs early after operation and persists beyond 2 years. Whether the regression of LV mass continues to decrease or stabilize over time is unclear.

Adrenergic beta-Antagonists↗
PubMed2004

Hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy is a fascinating disease of marked heterogeneity. Hypertrophic cardiomyopathy was originally characterized by massive myocardial hypertrophy in the absence of known cause, a dynamic left ventricular outflow obstruction, and increased risk of sudden death. It is now well accepted that multiple mutations in genes encoding for the cardiac sarcomere are responsible for the disease. Complex morphologic and pathophysiological differences, disparate natural history studies, and novel treatment strategies underscore the challenge to the practicing cardiologist when faced with the management of the patient with hypertrophic cardiomyopathy.

Cardiomyopathy, Hypertrophic↗
PubMed2004

Tachycardia during the valsalva maneuver: a sign of normal diastolic filling pressures.

Alteration of the loading conditions during the Valsalva maneuver is a helpful ancillary method in the noninvasive assessment of diastolic filling of the heart by Doppler echocardiography. When tachycardia is induced by the maneuver, mitral inflow velocity curves may become uninterpretable because of E velocity (the initial early diastolic velocity on the transmitral flow velocity curve) and A velocity (the velocity at atrial contraction on the transmitral flow velocity curve) wave fusion. To determine the clinical significance of the E velocity and A velocity wave fusion, our study assessed the relation between the heart rate response induced by the Valsalva maneuver and the left ventricular filling pressures measured during cardiac catheterization. In all, 77 patients performed the maneuver during continuous hemodynamic and electrocardiographic monitoring. The ratio between the baseline R-R interval and the shortest R-R interval during the maneuver was calculated. A ratio value higher than 1.1 was predictive of a pre-A pressure of less than 18 mm Hg (94% positive predictive value). Reflex tachycardia during the Valsalva maneuver and subsequent fusion of the E velocity and A velocity waves on the mitral velocity curves is a sign of normal left ventricular filling pressures.

Atrial Function, Left↗
PubMed2004

Extended septal myectomy for hypertrophic obstructive cardiomyopathy with anomalous mitral papillary muscles or chordae.

OBJECTIVES: Transaortic left ventricular septal myectomy yields excellent results for most severely symptomatic patients with hypertrophic obstructive cardiomyopathy. However, associated anomalies of the mitral subvalvular apparatus may prevent complete relief of obstruction, and mitral valve replacement has been advocated. We reviewed our results of procedures designed to relieve obstruction with preservation of the mitral valve. METHODS: Among 291 patients undergoing septal myectomy from 1975 to 2002, 56 (ages 2-77 years) had anomalous mitral subvalvular apparatus including anomalous chordae (n = 28) and papillary muscles with direct insertion into mitral leaflets (n = 13) or fusion to septum (n = 31) or free wall (n = 12); 82% of patients were in New York Heart Association class III or IV. Operation included resection of anomalous chordae (28 patients), relief of papillary muscle fusion (36 patients), and extended septal myectomy, wider at the apex than the base. RESULTS: There were no early deaths and no patients required mitral valve replacement. Mean peak pressure gradients decreased from 70 +/- 28 to 4.9 +/- 8.4 mm Hg and mean mitral regurgitation grade decreased from 2.3 to 1.0 (P <.001). Mean follow-up was 2.8 +/- 2.6 years. Freedom from reoperation at 4 years was 95%. There were 3 late noncardiac deaths; 98% of patients were in New York Heart Association class I or II. CONCLUSIONS: Hypertrophic obstructive cardiomyopathy associated with anomalous mitral papillary muscles or chordae can be successfully treated without mitral valve replacement by surgical relief of the anomalies and an extended septal myectomy; early mortality is low, obstruction and mitral regurgitation are significantly reduced, and late results are excellent.

Adolescent↗
PubMed2004

A nonresident cardiovascular inpatient service improves residents' experiences in an academic medical center: a new model to meet the challenges of the new millennium.

PURPOSE: Hospital practices in academic medical centers have fewer medical residents available to provide hospital care, necessitating alternative models for patient care. This article reports a new model for care of inpatients with cardiovascular diseases. METHOD: In 1998, a new nonresident cardiovascular patient care (Cardiology IV) service was implemented that used a team approach of staff attending cardiologists, cardiovascular fellows, midlevel practitioners (nurse practitioners and physician's assistants), and nurses to evaluate and treat patients. Standard dismissal information was collected for all patients dismissed in 1998 to compare diagnosis-related group, length of stay, in-hospital mortality, and 30-day readmission rates for Cardiology IV. These characteristics were compared with those for the remaining resident teaching services. Patients' satisfaction surveys from 1997 and 1998 were compared. Attending physicians' and internal medicine residents' satisfaction before and after the implementation of the new service was also compared. RESULTS: Staff and resident physicians were more satisfied with their hospital rotations after this intervention was introduced. Optimal patient care was maintained, and efficiency enhanced. Patients on Cardiology IV had a shorter length of stay compared with patients on the resident teaching service. CONCLUSIONS: This new hospital model has provided an alternative to patient care without the need for residents and protects education on the conventional teaching services. This model maintains optimal patient care and has resulted in enhanced satisfaction of attending staff and residents.

Academic Medical Centers↗
PubMed2003

Adverse prognosis of patients with hypertrophic cardiomyopathy who have epicardial coronary artery disease.

BACKGROUND: Adult patients with hypertrophic cardiomyopathy (HCM) may develop concomitant atherosclerotic coronary artery disease (CAD). There is a paucity of data on the clinical outcomes of HCM patients who have CAD. METHODS AND RESULTS: We examined the outcome of 433 adult patients with HCM according to the presence and severity of CAD. All patients were aged > or =21 years, had a left ventricular ejection fraction of > or =50%, and were without a history of prior surgical revascularization (mean age, 63 years; 212 men). Compared with HCM patients with mild-to-moderate or no CAD, those with severe CAD demonstrated markedly reduced survival. Ten-year overall survival was 46.1%, 70.5%, and 77.1% for patients with severe, mild-to-moderate, and no CAD, respectively (unadjusted P=0.0001; adjusted P=0.0006). For the end point of cardiac death, this survival was 62.3%, 81.0%, and 80.9% (unadjusted P=0.009; adjusted P=0.004). For the end point of sudden cardiac death, this survival was 77.4%, 93.2%, and 90.3% (unadjusted P=0.01; adjusted P=0.01). The presence of severe CAD also was highly predictive of these events (risk ratio for respective event: 2.31, 2.15, and 2.77) in multivariate models that additionally identified age, prior stroke, hyperlipidemia, and atrial fibrillation as significant covariates. CONCLUSIONS: Among adult patients with HCM who undergo coronary angiography, those who have concomitant severe CAD are at increased risk of death. This risk far exceeds historical death rates of CAD patients with normal left ventricular function.

Adult↗
PubMed2003

Myocardial bridging in adult patients with hypertrophic cardiomyopathy.

OBJECTIVES: This investigation examined the risk of sudden cardiac death and other mortality in adult patients with hypertrophic cardiomyopathy (HCM) who have myocardial bridging diagnosed at coronary angiography. BACKGROUND: Several reports have associated myocardial bridging with an adverse prognosis in pediatric HCM patients, but the prognosis of myocardial bridging in adult patients with HCM is unknown. METHODS: The coronary angiograms of 425 patients with HCM (mean age 60 +/- 15 years [range 18 to 89 years]) at the Mayo Clinic were examined for the presence of myocardial bridging. Clinical follow-up was conducted to assess mortality. Survival of patients with bridging was compared with HCM patients who also underwent angiography but who did not have evidence of bridging. RESULTS: A total of 64 patients (15%) had myocardial bridging. The mean follow-up for the entire study was 6.8 +/- 5.4 years. There was no difference in survival free of all-cause mortality (5-year estimate, bridging vs. no bridging, 91% vs. 85%; p = 0.42), all cardiac death (93% vs. 89%; p = 0.60), and sudden cardiac death (95% vs. 97%; p = 0.72). Univariate and multivariate proportional hazards models also did not identify the presence of bridging or specific characteristics of the degree or extent of bridging with a poor outcome. CONCLUSIONS: This study observed no increased risk of death, including sudden cardiac death, among adult patients with HCM who had myocardial bridging diagnosed at coronary angiography.

Adolescent↗
PubMed2002

Prevalence and severity of "benign" mutations in the beta-myosin heavy chain, cardiac troponin T, and alpha-tropomyosin genes in hypertrophic cardiomyopathy.

BACKGROUND: Genotype-phenotype correlative studies have implicated 8 particular mutations that cause hypertrophic cardiomyopathy (HCM) as "benign defects," associated with near-normal survival: N232S, G256E, F513C, V606M, R719Q, and L908V of beta-myosin heavy chain (MYH7); S179F of troponin T (TNNT2); and D175N of alpha-tropomyosin (TPM1). Routine genetic screening of HCM patients for specific mutations is anticipated to provide important diagnostic and prognostic information. The frequency and associated phenotype of these mutations in a large, unselected cohort of HCM is unknown. METHODS AND RESULTS: A total of 293 unrelated HCM patients were genotyped for the presence of a benign mutation. DNA was obtained after informed consent; specific MHY7, TNNT2, and TPM1 fragments were amplified by polymerase chain reaction; and the mutations were detected by denaturing high-performance liquid chromatography and automated DNA sequencing. Only 5 (1.7%) of the 293 patients possessed a benign mutation. Moreover, all 5 subjects with an ascribed benign mutation had already manifested clinically severe expression of HCM, with all 5 requiring surgical myectomy, 3 of the 5 having a family history of sudden cardiac death, and 1 adolescent requiring an orthotopic heart transplant. CONCLUSIONS: These findings demonstrate the rarity of specific mutations in HCM and challenge the notion of mutation-specific clinical outcomes. Fewer than 2% of the subjects harbored a benign mutation, and those patients with a benign mutation experienced a very serious clinical course.

Adolescent↗
PubMed2002

Natural history of asymptomatic mitral valve prolapse in the community.

BACKGROUND: The outcome of mitral valve prolapse (MVP) is controversial, with marked discrepancies in reported complication rates. METHODS AND RESULTS: We conducted a community study of all Olmsted County, Minn, residents first diagnosed with asymptomatic MVP between 1989 and 1998 (N=833). Diagnosis, motivated by auscultatory findings (n=557) or incidental (n=276), was always confirmed by echocardiography with the use of current criteria. End points analyzed during 4581 person-years of follow-up were mortality (n=96, 19+/-2% at 10 years), cardiovascular morbidity (n=171), and MVP-related events (n=109, 20+/-2% at 10 years). The most frequent primary risk factors for cardiovascular mortality were mitral regurgitation from moderate to severe (P=0.002, n=131) and, less frequently, ejection fraction <50% (P=0.003, n=31). Secondary risk factors independently predictive of cardiovascular morbidity were slight mitral regurgitation, left atrium > or =40 mm, flail leaflet, atrial fibrillation, and age > or =50 years (all P<0.01). Patients with only 0 or 1 secondary risk factor (n=430) had excellent outcome, with 10-year mortality of 5+/-2% (P=0.17 versus expected), cardiovascular morbidity of 0.5%/y, and MVP-related events of 0.2%/y. Patients with > or =2 secondary risk factors (n=250) had mortality similar to expected (P=0.20) but high cardiovascular morbidity (6.2%/y, P<0.01) and notable MVP-related events (1.7%/y, P<0.01). Patients with primary risk factors (n=153) showed excess 10-year mortality (45+/-9%, P=0.01 versus expected), high morbidity (18.5%/y, P<0.01), and high MVP-related events (15%/y, P<0.01). CONCLUSIONS: Natural history of asymptomatic MVP in the community is widely heterogeneous and may be severe. Clinical and echocardiographic characteristics allow separation of the majority of patients with excellent prognosis from subsets of patients displaying, during follow-up, high morbidity or even excess mortality as direct a consequence of MVP.

Aged↗
PubMed2002

Low-output, low-gradient aortic stenosis in patients with depressed left ventricular systolic function: the clinical utility of the dobutamine challenge in the catheterization laboratory.

BACKGROUND: Although aortic valve replacement can be performed at an acceptable risk level in selected patients with left ventricular systolic dysfunction and low-output, low-gradient aortic stenosis, not all patients presenting with these hemodynamics will benefit from the operation. Some patients may have only mild aortic stenosis, despite a small calculated valve area. We report on the clinical utility of diagnostic dobutamine stimulation during cardiac catheterization in these diagnostically challenging patients. METHODS AND RESULTS: Thirty-two patients with low-output, low-gradient aortic stenosis and an ejection fraction <40% had dobutamine infusion in the catheterization laboratory. On the basis of the results of the dobutamine test, 21 patients underwent aortic valve replacement. All patients with a final aortic valve area < or =1.2 cm2 at peak dobutamine infusion and a mean gradient of >30 mm Hg were found to have severe calcific aortic stenosis at operation. In the 15 patients in whom contractile reserve was identified during dobutamine challenge (increase in stroke volume >20%), 1 patient died perioperatively (7% mortality) and 12 patients were alive in New York Heart Association class I or II status at follow-up. CONCLUSIONS: In patients with left ventricular systolic dysfunction and aortic stenosis with a low output and a low mean gradient, dobutamine challenge may aid in selecting those who would benefit from an aortic valve operation.

Adrenergic beta-Agonists↗