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Biomedical subjects

W A Pocock

Publications and source records attributed to W A Pocock.

At least 19 recordsLinked to original sources
PubMed1994

The spectrum of severe rheumatic mitral valve disease in a developing country. Correlations among clinical presentation, surgical pathologic findings, and hemodynamic sequelae.

OBJECTIVE: To describe the demographic, pathologic, and hemodynamic profiles of patients with severe rheumatic mitral valve disease in a developing country and to assess their relation to uncontrolled rheumatic disease activity. DESIGN: Retrospective, cross-sectional, cohort study. SETTING: Tertiary medical center in Soweto, South Africa. PATIENTS: 714 of 737 consecutive black patients, 4 to 73 years old, with pure mitral regurgitation, pure mitral stenosis, or mixed mitral disease who had mitral valve surgery and in whom preoperative and surgical data were concordant. MEASUREMENTS: Valve lesions were evaluated on the basis of clinical, echocardiographic, hemodynamic, and surgical pathologic data. Active rheumatic carditis was diagnosed according to clinical evidence for concurrent acute rheumatic fever (Jones criteria), macroscopic appearances at surgery, and histologic findings. RESULTS: 219 patients had pure mitral regurgitation, 275 had pure mitral stenosis, and 220 had mixed lesions. Ongoing rheumatic activity was diagnosed in 106 patients with pure regurgitation (47%) and in only 5 patients with pure stenosis (2%). Pure regurgitation was the most common lesion in the first and second decades; the relative prevalence of pure stenosis increased with age. Purely regurgitant valves had pliable, unscarred leaflets (95%), dilated mitral annuli (95%), elongated chordae tendineae (92%), and anterior leaflet prolapse (81%). In contrast, purely stenotic valves had fused leaflet commissures (100%) and rigid leaflets (38%) but no evidence of prolapse. CONCLUSIONS: The spectrum of rheumatic mitral valve disease that is hemodynamically severe in developing countries differs from that currently reported in the United States. Severe, pure rheumatic mitral regurgitation is as prevalent as pure stenosis but has an entirely different time course, surgical anatomy, and relation to disease activity, suggesting a separate pathophysiologic mechanism.

Adolescent↗
PubMed1990

Mechanisms and management of heart failure in active rheumatic carditis.

Fulminating active rheumatic carditis has been observed for over three decades in this environment with no recent alteration in either the incidence or the pattern of presentation. Heart failure (in this context defined as 'an inadequate circulation at rest together with a raised pulmonary venous pressure, with or without an associated high systemic venous pressure in the absence of haemodynamically significant tricuspid valve disease or pericardial effusion') is prevalent but occurs only when a haemodynamically important left-sided valve lesion supervenes. Regurgitation is the predominant valve lesion and involves principally the mitral valve. Mitral annular dilatation is marked and predisposes to lengthening--or rupture--of chordae tendineae and prolapse of the anterior leaflet. The resultant cardiac work-overload apparently perpetuates or aggravates the rheumatic activity. Heart failure, as defined, whether caused by or associated with active rheumatic carditis, makes surgical management of the valve lesion mandatory as a life-saving measure. Aggressive medical therapy for heart failure, which should include vasodilator drugs and especially angiotensin-converting enzyme inhibitors, provides temporary improvement only. Contrary to ongoing doctrine, treatment with steroid drugs in this context is neither life-saving nor beneficial.

Adolescent↗
PubMed1989

Functional anatomy of severe mitral regurgitation in active rheumatic carditis.

The mechanism of severe mitral regurgitation (MR) due to active rheumatic carditis is ill defined. This study involved 73 patients, aged 7 to 27 years (mean 13), with severe MR and active rheumatic carditis who were subjected to surgery. Sixty-one were studied retrospectively (group 1) and 12 prospectively (group 2). Active rheumatic carditis was diagnosed according to the modified Jones' criteria, morphologic appearances of the heart at operation and histology of the valve. All patients had preoperative 2-dimensional echocardiographic and intraoperative assessment of the mitral valve apparatus. The presence of mitral valve prolapse--defined as failure of leaflet edge coaptation resulting in systolic displacement of the free edge of the involved leaflet toward the left atrium--was determined in all patients. Mitral anular diameter and maximal systolic chordal length were measured at 2-dimensional echocardiography in group 2 patients and compared to values obtained from matched control subjects. Anular and chordal dimensions in 6 of the group 2 patients were correlated with precise measurements obtained at surgery. Mitral valve prolapse involving the anterior leaflet was detected on echocardiography and confirmed at surgery in 69 patients (94%). Mitral anular dilatation was observed at operation in 70 patients (96%). Maximal anular diameter was significantly greater (p less than 0.0001) than in matched control subjects (37 +/- 4 vs 23 +/- 2 mm). The mean anular dimension measured at surgery (36 +/- 3 mm) was similar to that obtained by echocardiography and individual values using the 2 methods correlated well (r = 0.93). Chordal elongation was observed in 66 patients at operation (90%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Mitral valve billowing and prolapse: perspective at 25 years.

The syndrome of primary mitral leaflet billow, with or without prolapse, is associated with myxomatous degeneration of the mitral valve apparatus, mainly the posterior leaflet, and the syndrome may be familial. It manifests clinically with an isolated nonejection systolic click (billow), a murmur of mitral regurgitation that is usually late systolic (prolapse), or a combination of murmur and click. Echocardiography identifies and assesses the extent of the billowing of mitral leaflet bodies but there are no specific echocardiographic criteria that can differentiate normal from pathological billowing. Similarly, a prolapsed leaflet is not detected echocardiographically when there is localized and mild failure of leaflet edge apposition but a more severely prolapsed, or flail, leaflet can be demonstrated and confirmed by that technique. Symptoms of the syndrome include anxiety, chest pain and palpitations. The resting electrocardiogram may show ST segment and T wave abnormalities. The majority of patients have a benign course and require reassurance only. Complications include systemic emboli, infective endocarditis, progression to severe mitral regurgitation, arrhythmias and, rarely, sudden death. Patients with prolapse of a leaflet edge are more likely to develop complications than those with only billowing of the leaflet bodies. Surgery, preferably valvuloplasty, is required for severe regurgitation and may also be indicated for potentially lethal tachyarrhythmias unresponsive to medical therapy. Mitral leaflet billow and prolapse may be secondary to, or associated with, many conditions. The prognosis is then principally that of the underlying disease of which ischemic heart disease and hypertrophic cardiomyopathy are the most important.

Death, Sudden↗
PubMed1987

Pulmonary arterial thrombosis in secundum atrial septal defect.

Nineteen adolescent or adult patients with secundum atrial septal defect (ASD) underwent pulmonary arteriography to evaluate the presence of proximal pulmonary arterial (PA) thrombosis. This procedure demonstrated proximal PA thrombosis in 8 patients (group 2). These patients had a distinctive hemodynamic profile, consisting primarily of significant PA hypertension. None of the 11 patients with normal angiograms (group 1) had severe PA hypertension (p less than 0.0001). Proximal PA thrombosis appears to be the major factor in the development and progression of PA hypertension in adult patients with ostium secundum ASD. Pulmonary angiography should be undertaken in all adult patients with ostium secundum ASD who have at least moderate PA hypertension. Long-term anticoagulation is advocated for patients with PA thrombosis irrespective of a decision for surgical intervention.

Adolescent↗
PubMed1987

Echocardiographic and hemodynamic correlates of diastolic closure of mitral valve and diastolic opening of aortic valve in severe aortic regurgitation.

Acute severe aortic regurgitation (AR) is characterized by a steep increase in left ventricular end-diastolic pressure, exceeding left atrial pressure and occasionally equilibrating with aortic diastolic pressure. These pressure phenomena correlate with the M-mode echocardiographic (echo) findings of diastolic closure of the mitral valve (DCMV) and diastolic opening of the aortic valve (DOAV). Six men, aged 23 to 48 years, with recent-onset, severe AR were evaluated by M-mode echo and pressures at cardiac catheterization. DCMV was seen in all 6 patients and DOAV in 4. Near-constant time intervals from the preceding R wave of the electrocardiogram to DCMV and DOAV were seen, even in 3 patients with varying RR intervals (1 with atrial fibrillation and 2 with asynchronous and demand atrial pacing). When the RR intervals were shorter than these intervals, DCMV and DOAV did not occur. Increasing the heart rate in the 2 patients by atrial pacing resulted in a marked decrease in left ventricular end-diastolic pressure. In conclusion, DCMV and DOAV have a near constant relation to the preceding R wave of the electrocardiogram, DCMV with competence of the mitral valve must be present for DOAV to occur, DOAV indicates that the diastolic blood pressure equals left ventricular end-diastolic pressure, and heart rate is an important factor influencing the hemodynamic and echocardiographic parameters in recent-onset, severe AR.

Adult↗
PubMed1986

Contribution of echocardiography and immediate surgery to the management of severe aortic regurgitation from active infective endocarditis.

The timing of surgery in patients with severe aortic regurgitation and left ventricular (LV) failure, particularly when associated with active infective endocarditis (IE), is of the utmost importance. From July 1982 to May 1984, 34 patients, aged 15 to 60 years, with severe aortic regurgitation underwent immediate (within 24 hours of diagnosis) aortic valve surgery. All patients were in New York Heart Association class IV for LV failure. Eighteen patients had right-sided heart failure. Decision for immediate surgery was based on the echocardiographic demonstration of diastolic closure of the mitral valve or of vegetations on the aortic valve. Premature closure of the mitral valve was demonstrated echocardiographically in 17 patients, 13 of whom had diastolic crossover of LV and left atrial pressure tracings recorded at surgery. IE of the aortic valve was confirmed at surgery in 29 patients, 27 of whom had vegetations on echocardiography. Seven patients required replacement of both aortic and mitral valves. Antibiotic therapy for IE was started immediately after blood cultures were taken and continued for 4 to 6 weeks postoperatively. The mortality rate within 30 days of surgery was 6% for the group as a whole and 7% for those with IE. Mean follow-up period for the 32 survivors was 10.6 months. There were 2 late deaths. No patient had periprosthetic regurgitation or persistence of endocarditis. Procrastination in referral for surgery of these extremely ill patients is not justified and is likely to be associated with higher risks of morbidity and mortality.

Adolescent↗
PubMed1984

Sotalol, hypokalaemia, syncope, and torsade de pointes.

Thirteen patients developed syncope and a prolonged QTc interval while taking therapeutic doses of sotalol. Polymorphous ventricular tachycardia was observed in 12 patients, and criteria typical of torsade de pointes were present in 10. In 12 patients sotalol had been given with hydrochlorothiazide in a combined preparation, Sotazide, but with inadequate or no potassium supplementation. Serum potassium concentrations were reduced in eight patients. Four patients were taking other drugs known to prolong the QT interval, including disopyramide (three patients) and tricyclic antidepressants (two patients). The QT interval returned to normal in all patients after withdrawal of the drugs and correction of the hypokalaemia. Thus even in low dosage sotalol may be hazardous in the presence of hypokalaemia or when combined with drugs that also prolong the QT interval. The use of sotalol concurrently with potassium losing diuretics, such as the combined preparation Sotazide, may expose the patient to unnecessary risk and should be avoided unless the class III antiarrhythmic action of this unique beta adrenoreceptor blocking agent is also required.

Adult↗
PubMed1983

Further experience with long-term captopril therapy in severe refractory congestive heart failure.

Fifty patients in severe congestive heart failure (CHF) were treated with captopril (Capoten; Squibb), an oral angiotensin-converting enzyme inhibitor, over a 2-year period (range 3-24 months, mean 8,6 +/- 7,7 months). At entry, all patients were in New York Heart Association (NYHA) functional class IV despite high-dose diuretic and conventional vasodilator therapy. The overall cumulative survival at 6 and 12 months was 64% and 53% respectively. There were 22 deaths (18 during captopril therapy) including 8 sudden deaths. At 2-year follow-up (mean 14,6 +/- 6,9 months), there were 25 survivors on captopril; 18 in NYHA class I or IIS and 7 in class IIM or III. Diuretic requirements were decreased considerably in all. Side-effects were common but transient and in no case did captopril have to be withdrawn. We confirm our earlier conclusion that captopril has long-term beneficial effects and is a highly effective drug in the treatment of patients with CHF refractory to currently accepted therapy. Sudden death despite satisfactory clinical improvement continues to cause concern. Precautions which may reduce or avoid these are briefly discussed.

Adolescent↗
PubMed1982

Long-term captopril therapy in severe refractory congestive heart failure.

1 The favourable haemodynamic effects of captopril in patients with congestive heart failure have been reported. 2 We have treated 25 patients with severe chronic congestive heart failure with captopril in doses of 75-450 mg daily. Before entering the study all patients remained in New York Heart Association functional class IV despite high-dose diuretic and vasodilator therapy. 3 Mean cardiothoracic ratio was 60%, and all patients had a shortening fraction of 18% or less on echocardiography (normal 25 to 40%). 4 Five patients died within one month of captopril and five between four and seven months, three of whom had improved to class IIM and one to IIS before death. 5 Of the 15 survivors one was referred for a heart transplant when he had improved to class IIM. The remaining 14 patients were followed for 8-16 months. Ten improved to New York Heart Association class I or IIS and four to class IIM or III. Diuretic requirements were decreased considerably in all 14. Side effects were common but captopril did not have to be withdrawn. Captopril is a highly effective drug in the treatment of patients with congestive heart failure refractory to currently accepted therapy.

Adolescent↗