The coming of age of cardiology in Singapore.
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Cardiology↗
Biomedical subjects
M C Tong
Publications and source records attributed to M C Tong.
Ventricular septal rupture in acute myocardial infarction.
This is a review of 31 patients with ventricular septal rupture occurring in myocardial infarction which have been managed at the Singapore General Hospital. Ventricular septal rupture occurs more frequently in the elderly, in females and those presenting with the first myocardial infarction. Very few have a prior history of stable angina pectoris before the myocardial infarction. Sudden deterioration as manifested by an increase in heart rate, fall in blood pressure and signs of right heart failure in a patient with acute myocardial infarction (AMI) especially if accompanied by a systolic murmur should encourage a search for a mechanical cause, especially a ventricular septal rupture. 2D echocardiography or Swan-Ganz catheterisation are 100% diagnostic and can be easily and rapidly done at the bedside. Medical management includes vasodilator therapy and inotropic support. Intra-aortic balloon counterpulsation is especially useful and was instituted in 6 patients. Early surgical repair of the ventricular septal defect is important if overall prognosis of these patients is to be improved. Our operative survival of 42.9% is comparable to others, considering that without surgery all have died. Survival appears to be related to the site of the myocardial infarction (very poor prognosis in inferior myocardial infarction), operative treatment (no survivors if treated conservatively) and the mode of presentation (poor prognosis in patients who develop a ventricular septal rupture while in hospital).
Aged↗
Coronary artery bypass in patients with impaired left ventricular function.
Myocardial revascularisation in patients with severe left ventricular dysfunction has been shown to improve survival. This report analyses the efficacy of myocardial revascularisation in this subset of patients with coronary artery disease manifesting severe left ventricular dysfunction on the basis of left ventricular ejection fraction (LVEF). Twenty-two consecutive patients with coronary artery disease complicated by severe left ventricular dysfunction underwent aorta-coronary bypass electively at Singapore General Hospital for the 3 year period ending February 1989. Twenty-one patients have angina +/- congestive heart failure refractory to medical therapy. One patient had congestive heart failure and objective evidence of ischaemia confirmed by preoperative thallium stress test. Nineteen (82.6%) patients had triple-vessel coronary artery disease. The mean LVEF for the series was 25% with the range from 10-13%. The duration of follow up was 6 months to 3 years (mean 24 months) with follow up survival data on 100% of patients. The hospital mortality was 9% (2/22) and there were 3 late deaths. Of the 17 survivors available for direct assessment, 12 reported improvement in their symptoms and 3 are completely asymptomatic. These preliminary results indicate that myocardial revascularisation can be performed in patients with severe LV dysfunction at an acceptable risk and that operation results in improvement in survival expectation and symptoms compared with medical therapy.
Angina Pectoris↗
Left main coronary artery obstruction: surgical experience with 93 patients.
Among patients with ischemic heart disease, those with left main stem coronary artery stenosis has attracted most attention due to their ominous prognosis. During the period from August 1982 to February 1989, 93 patients underwent left main coronary artery revascularisation procedures at Singapore General Hospital. All the patients had greater than 75% obstruction of the left main coronary artery. Significant triple vessel disease occurred in 35 patients (37.6%), double vessel disease in 32 patients (34.4%), single vessel disease in 21 patients (22.6%) and left main coronary as an isolated lesion in 5 patients (5.4%). The overall hospital mortality rate is 6.5% and perioperative infarction rate is 8.6%. Since mid-1985, the hospital mortality rate has been reduced to 3.7% and the perioperative infarction rate to 4.9%. Average grafts per patient was 3.5. Intra-aortic balloon pump was used in 5 patients. Follow up period was from 5 months to 84 months with a mean of 36 months with the majority of patients in either New York Heart Association Class I or II and still alive.
Cardiac Catheterization↗
Anti-arrhythmic surgery for atrioventricular junctional and atrioventricular re-entrant tachycardia--a report of six cases.
Since 15th March 1989, six patients with recurrent supraventricular tachycardia (SVT) had antiarrhythmic surgery performed. There were 4 males and 2 females, ages ranged from 23 to 62 years (mean 41 years). Two of these patients with the Wolff Parkinson White (WPW) syndrome also had syncope. Five of these patients had atrioventricular re-entrant tachycardia (AVRT) involving the bypass tracts. Two patients with the WPW syndrome had persistent antegrade conduction, two had intermittent conduction and the last patient had no antegrade conduction via the bypass tract. The bypass tracts were localised at the left free wall in all the five patients. Only one patient had atrioventricular junctional re-entrant tachycardia (AVJRT) of the slow-fast type. The indications for surgery for these patients include failed medical therapy, "dangerous" arrhythmias and patient's preference. All the patients had surgery performed using the endocardial dissection technique on the cardioplegic heart. There were no perioperative mortality and morbidity. All the patients were discharged within 2 weeks. To date, none of the patients had clinical recurrence of SVT and only one patient remained in atrial fibrillation and is on digoxin. In conclusion, antiarrhythmic surgery should be considered for patients with "symptomatic" palpitations as it is curative with a resumption to normal life.
Adult↗
Surgical revascularisation for diffuse CAD--an experience in 116 cases.
There were 94 male and 22 female, age ranges 32 to 71 years with a mean age of 54 years. All of them had angina pectoris and strong positive stress test inspite of maximum medical treatment. All had severe triple vessel disease including (12 (10%) had critical left main stem lesion, 68 (52%) were diabetic and hypertensive, 51 (44%) had myocardial infarct with 16 (14%) of them showing global hypokinesia of ejection fraction 30%. The average grafts per patient was 3.8 Seventy-nine patients (68%) and RCA endarterectomy; 19 (16%) had right and left coronary endarterectomy and 18 (15%) had left coronary artery endarterectomy. One-hundred and three (86%) were reconstructed with saphenous vein graft. 13 (12%) with IMA grafts. There was no operative mortality. Two hospital deaths and two late deaths occurred in those patients who had very poor left ventricular function. The perioperative infarct rate was 2.7%. All patients were followed-up regularly at 2 weeks, 3 months, 6 months, postoperatively. The mean follow-up was 18 months ranging 10 to 43 months. Clinically over 95% are free from angina pectoris with improved effort tolerance. We conclude that endarterectomy with patch angioplasty is an effective and safe procedure in treating Diffuse Coronary Artery Disease which cannot be treated by bypass alone. The incidence of Diffuse Coronary Artery Disease is likely to increase in the future as the percutaneous balloon angioplasty is becoming more widely practised and Re-do CABG patient would come to surgery at a more advanced state of the disease.
Adult↗
The influence of verapamil on the gastric effects of stress in rats.
The influence of verapamil on stress- or bethanechol-induced gastric effects was investigated in rats. Intraperitoneally injected verapamil (1, 2 or 4 mg/kg), given 30 min beforehand, dose-dependently prevented gastric glandular ulceration, mast cell degranulation and the increased stomach wall contractions evoked by restraint at 4 degrees C for 1 h. Gastric acid secretion, as well as ulceration in both the forestomach and glandular segment, produced by subcutaneously-injected bethanechol (3.2 mg/kg) were also inhibited. It is concluded that decreased amine release from the mast cells, stomach wall relaxation and reduced gastric acid were responsible for the ulcer-antagonising effects of the calcium-entry blocker. The possible antiulcer actions of verapamil are discussed in the light of present knowledge regarding calcium involvement in the various mechanisms thought to contribute to the pathophysiology of stress ulceration in rat stomachs.
Animals↗
Anorectal anomalies: a review of 49 cases.
A series of forty-nine cases of anorectal anomalies treated in the Department of Surgery, Singapore General Hospital, is reviewed. The incidence of ano-rectal malformation in the Singapore population is estimated to be one in 11,500 live births. There is a significant male preponderence with a ratio of 7 to 3. Supralevator lesions accounted for 55% of the cases and of this group, 31% had associated congenital anomalies. In contrast only 11% of the low anomalies had other congenital defects. All patients were treated surgically either by anoplasty for the low lesions or staged rectoplasty for the intermediate and high lesions. The results of surgery for the low anomalies were uniformly good. In the group with high anomalies 7 cases had a good results, 21 had a fair result with occasional soiling only, and 2 cases had a poor result with frank incontinence.
Anal Canal↗
Tubeless anesthetic technique for optimal carbon dioxide laser surgery of the larynx.
PURPOSE: To evaluate the operative conditions and safety of a tubeless technique of anesthesia for carbon dioxide laser surgery of the larynx. MATERIALS AND METHODS: This prospective study evaluated 78 consecutive procedures in 72 adult patients undergoing carbon dioxide laser microlaryngeal surgery. Anesthesia was maintained by an intravenous infusion of Propofol (ICI Pharmaceuticals, Cheshire, UK) while the patient breathed spontaneously without endotracheal intubation. RESULTS: The operative conditions were optimal in 76 of the 78 procedures providing a clear uninterrupted view of the larynx with no combustible material in the surgical field. CONCLUSIONS: This series shows the technique described to be safe without risk of combustion and provides an unobstructed view to the larynx.
Adolescent↗
Acquired posterior choanal stenosis and atresia: management of this unusual complication after radiotherapy for nasopharyngeal carcinoma.
PURPOSE: To report on acquired posterior choanal stenosis and atresia after radiotherapy for nasopharyngeal carcinoma. MATERIALS AND METHODS: Four patients with acquired bilateral choanal atresia and 2 with severe unilateral choanal stenosis in the posterior choanae were identified after treatment of nasopharyngeal carcinoma with radiotherapy. The mean age was 42 years (range, 29 to 48 years). Two patients had stage II, and 4 had stage III disease, according to Ho's classification. They all received a 66 Gy dose of external irradiation delivered to the nasopharynx, and a mean dose of 62.6 Gy to the neck. Five patients had an additional 20 Gy delivered to the parapharyngeal region, and 1 patient had intracavitatory brachytherapy of 18 Gy delivered to the nasopharynx. The mean onset of symptoms was 10.5 months (range, 2 to 40 months) postirradiation. All patients were treated by transnasal endoscopic resection. Merocel epsitaxis packing (Medtronic Xomed, Jacksonville, FL) was used to stent the nasal airway for 2 weeks postoperatively. RESULTS: The mean follow-up was 16.2 months (range, 14 to 18 months) after surgery. Four patients (67%) were symptom-free. Two patients (33%) had unilateral restenosis in the postnasal space that required revision surgery and further nasal stenting for 2 weeks, and both were subsequently free from further restenosis. No adverse postoperative complication occurred. CONCLUSION: Acquired posterior choanal stenosis and atresia is an unusual long-term complication after radiotherapy that can be successfully treated with transnasal endoscopic resection. A 2-week Merocel nasal stent is recommended to prevent restenosis in the posterior choanae.
Adult↗