Biomedical subjects
Publications and source records attributed to V F Huckell.
A sedentary 60-year-old man newly diagnosed with diabetes insists on seeing a cardiologist because he has read that diabetes damages blood vessels. Several questions submitted by participants and the corresponding answers (based on group discussion and on the actions taken for the real patient) are presented.
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There is an increasing body of clinical trial evidence to support the use of angiotensin-converting enzyme (ACE) inhibitors in the management of patients following myocardial infarction (MI). Enthusiasm for the use of ACE inhibitors in the acute phase of MI had previously been tempered by the adverse results of an early trial. However, exciting new information is available from several large, randomized studies that has not only quelled those initial concerns but also attests to the efficacy of using this class of medication in the first 24 h after an acute MI. A Canadian National Opinion Leader Symposium was held in November 1995 to review the results of the major ACE inhibitor clinical trials and to discuss key issues and controversies surrounding their use in acute MI. The focus of this paper, the first of two parts, is on the results of the major ACE inhibitor clinical trials.
Over the past 10 years, several clinical studies have concluded that, in patients already receiving conventional therapies, angiotensin-converting enzyme (ACE) inhibitors further reduce the risk of death following myocardial infarction (MI). Post-MI ACE inhibitors have proven to be effective as long term therapy in high risk patients as well as when used for much shorter periods in a broad patient population. However, while considerable mortality data have been collected, the effects of ACE inhibitors post-MI on other cardiovascular outcomes have not been as well documented. In addition, a number of issues regarding the most effective use of these agents remain unresolved. This paper, the second of two parts, focuses on the clinical issues and controversies surrounding the use of ACE inhibitors following acute MI. The effects of ACE inhibitors on the outcomes of sudden death, nonsudden death, recurrent angina, mitral regurgitation and left ventricular dysfunction are reviewed and potential mechanisms of action are proposed. In addition, ACE inhibitor therapy is discussed in terms of patient selection criteria, choice of agent, optimal dosing regimen, concomitant use of other therapies and relative costs of treatment. Finally, potential mechanisms of action of ACE inhibitors are proposed for each of the outcomes examined.
Right outflow tract obstruction due to neurofibroma is rare, with only four cases identified in the world literature. Obstruction due to a pedunculated neurofibroma has never been reported. A 36-year-old woman with no known heart disease presenting with dyspnea, palpitations and chest pain was shown on echocardiogram to have a mobile right ventricular mass. Cardiac catheterization revealed normal coronary arteries and right ventricular outflow tract obstruction by a pedunculated mass, which was surgically removed and histologically proven to be a benign neurofibroma. Following surgery the patient's symptoms disappeared, with no recurrence three years postoperatively.
Exercise-induced left bundle branch block is a relatively rare finding during exercise tolerance testing. A 36-year-old female with intermittent exercise-induced left bundle branch block, a MIBI study suggesting anterior ischemia and normal coronary arteries is reported. A review of the English and French language literature published from January 1985 to January 1996 is presented. Exercise-induced left bundle branch block has been reported in association with and without structural heart disease. Pooled mortality in the group with structural heart disease was 2.7% per year, and mortality was 0.17% per year when no structural heart disease was identified. Exercise-induced left bundle branch block has been reported to resolve with therapy. Noninvasive testing appears to have limited ability to detect or exclude coronary artery disease in this group. If a definitive cardiac diagnosis is required, strong consideration should be given to coronary angiography.
OBJECTIVES: We postulated that femoral vein delivery of contrast medium because of streaming, might enhance precordial echocardiographic detection of patent foramen ovale. BACKGROUND: Although precordial contrast echocardiography is widely used to diagnose patent foramen ovale, this method is limited by poor sensitivity. Previous investigators have demonstrated enhanced detection of atrial defects by the dye-dilution technique after delivery of contrast medium into the inferior rather than the superior vena cava. METHODS: Transthoracic contrast examinations were performed in a randomly selected group of 70 patients (without previous history of cerebral or systemic embolus) undergoing cardiac catheterization. Paired contrast agent injections (10 ml dextrose in water/0.25 ml air) were administered from an upper extremity vein and femoral vein in each patient during spontaneous respiration, cough and Valsalva maneuvers. Studies were interpreted by an experienced echocardiographer unaware of the sequence and site of injections. Positive studies were semiquantitatively graded from +1 (minimal left ventricular opacification) to +4 (intense left ventricular opacification). Catheterization and echocardiographic assessment of patent foramen ovale were compared in 21 subjects. RESULTS: Patent foramen ovale was detected significantly more often during femoral vein versus upper extremity contrast delivery (23 of 70 patients [prevalence 33%] vs. 9 of 70 patients [prevalence 13%], p < 0.001). The intensity of left ventricular opacification was also greater during femoral vein contrast injection. Precordial echocardiography combined with femoral contrast delivery was significantly more sensitive than cardiac catheterization for assessment of patent foramen ovale (8 of 21 patients vs. 2 of 21 patients, p < 0.05). CONCLUSIONS: Femoral vein contrast delivery significantly enhances the ability of precordial contrast echocardiography to diagnose patent foramen ovale. Physiologic patency of the foramen ovale is more common (prevalence 33%) than previously documented.
Emery-Dreifuss disease is a benign X-linked muscular dystrophy characterized by a distinct pattern of muscle weakness, which is of insidious onset and slow progression. It is associated with atrial paralysis that results in sudden death in early adulthood if left untreated. The authors report the documentation of electrical and mechanical silence confined to the atria in a patient with this disease. Electrocardiography and electrophysiological study document the absence of electrical atrial activity, and inability to pace the atria. Hemodynamic studies demonstrate the absence of A waves, and angiography revealed immobility of the atria. This patient has done well following the institution of permanent ventricular pacing. His brother, who also had muscular dystrophy, died a sudden cardiac death at the age of 29 after refusing medical intervention. Emery-Dreifuss muscular dystrophy is particularly worthy of recognition because of the preventable occurrence of sudden death in young patients with an otherwise excellent prognosis. Permanent ventricular pacing is indicated.
Origin of a pulmonary artery from the aorta is a rare congenital defect which usually is fatal if not surgically corrected in infancy. Medical treatment often is unsatisfactory because of progressive heart failure. Described is a 19-year follow-up of a patient who underwent surgery at age three weeks to correct a right pulmonary artery from the aorta.
Leiomyosarcomas are extremely rare primary cardiac tumours. A 46-year-old woman presenting with symptoms and signs of rapidly progressive left ventricular failure and apparent systemic lupus erythematosus was subsequently found to have a grade III/III left atrial leiomyosarcoma which was confirmed surgically. Pathology showed a cellular neoplasm arranged in fascicles with multinucleated giant cells, with areas of high grade sarcomatous change. The patient died seven months postoperatively with intractable heart failure. At autopsy, tumour infiltrated the pericardium, both atria and the right ventricle, with invasion of the diaphragm and posterior mediastinum. The current world literature is reviewed with respect to this rare and often misdiagnosed tumour.
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This paper describes the anaesthetic management of a 29-year-old woman for an elective repeat Caesarean section. A diagnosis of peripartum cardiomyopathy (PPCM) had been made after her first delivery by Caesarean section three years earlier. Although the patient was currently asymptomatic, recent echocardiography demonstrated persistent left ventricular dilatation. The choice of haemodynamic monitors and the clinical significance of PPCM in this situation are discussed.
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The authors prospectively compared the ability of Tc-99m pyrophosphate (PYP) and Tc-99m methylene diphosphonate (MDP) to detect acute myocardial infarctions. The agents used were PYP (12 mg) with 3.4 mg of stannous chloride, MDP (10 mg) with 1.0 mg of stannous chloride, and MDP (10 mg) with 3.4 mg of stannous chloride. Imaging was performed on three consecutive days on 34 patients with proven myocardial infarctions, using the same agent on the first and third days of the study and an alternate agent on the second day. Agents were assigned randomly to each of six groups of patients. First images were obtained an average of 3.7 days (range, one to six days) following myocardial infarction. Seventeen of 23 patients (75%) had images positive for acute myocardial infarction with Tc-99m PYP, whereas only two of 21 patients (9.5%) had positive studies with Tc-99m MDP with 3.4 mg of stannous chloride and one of 24 patients (4.2%) had positive studies with Tc-99m MDP and 1.0 mg of stannous chloride. All three myocardial infarctions detected by Tc-99m MDP were extensive and transmural. When MDP and PYP were both positive in the same patient, the apparent size of the myocardial infarction was much smaller with the MDP. It is concluded that MDP can detect only large myocardial infarctions, has poor localization in the infarcted tissue, and varying the stannous chloride content of the preparation does not improve the ability of MDP to detect acute myocardial infarctions.
Amiodarone is an effective antiarrhythmic that has been used in Europe for over a decade and has been available for investigational use in North America for a shorter time. It has several well recognized side effects. Recent reports have related pulmonary disorders to the use of this drug; fibrosing alveolitis has been found by lung biopsy. Amiodarone's toxicity to the lung does not appear to be dose-related. Besides cessation of amiodarone administration, management of this complication includes steroid therapy. A case is described of nonspecific diffuse alveolar damage syndrome in a patient who had received amiodarone.