- Email: [email protected]
T WAVES IN LONG Q-T SYNDROMES
171 or torsade de pointes. On the tenth day, replacement therapy with thyroxine, 25 pg progressively increased to 100 ltg daily, and hydrocortisone, 30 mg daily, was started. One month later, the Q-T interval had shortened to 420 ms (Q-Tc 392 ms, 52/min) and peripheral thyroid hormone levels were normal. She had no palpitation, dizziness, or syncope during nine months of follow-up and the Q-T interval remained normal (400 ms) on the
arrhythmia
same treatment.
Torsade de pointes related to Q-T prolongation may be a cause of ventricular arrhythmias during hypothyroidism, as demonstrated in our patient and in the case reported by Kumar et al.2 However, these two patients had secondary hypothyroidism due to panhypopituitarism. By contrast, the case reported by Guthrie et aP had peripheral hypothyroidism. Whether the association with other pituitary deficiencies increases the risk of torsade de pointes in Q-T interval prolongation due to hypothyroidism deserves further
The mechanism is said to be differing repolarisation times in different areas of the ventricle. A cellular defect would therefore have to be patchy to produce this effect. In ischaemic heart disease, when similar changes are found,2 sympathetic imbalance is at least as likely a cause as the myocardial damage. Similarly in alcoholic heart disease, an autonomic neuropathy could be the explanation for
Q-T prolongation. In the hereditary long Q-T syndromes, necropsy studies have failed to demonstrate a consistent abnormality, although James et al have described inflammation or degeneration of the intracardiac nerves
and sinoatrial node.3 There
are
several
reasons
for
supposing, therefore, that the underlying abnormality may be an imbalance of sympathetic innervation rather than a myocardial cellular defect, at least on current evidence. Woodend General Hospital, Aberdeen AB9 2YS
study.
JOHN C. S. DEAN
1. Schwartz
CHARLES EIFERMAN PHILIPPE CHANSON ARIEL COHEN JEAN LUBETZKI
Hôpital Lariboisière, 75475 Paris, France
1. Guthrie GP
Jr, Hunsaker JC, O’Connor WN. Sudden death
N Engl J Med 1987; 317: 1291. 2. Kumar A, Bhandari AK, Rahimtoola SH Torsade prolongation in association with hypothyroidism.
in
hypothyroidism.
de pointes and marked QT Ann Intern Med 1987; 106:
712-13.
T WAVES IN LONG Q-T SYNDROMES
SIR,-Dr Attwell and Dr Lee (May 21, p 1136) emphasise the of the corrected Q-T interval and its variation with heart rate in the diagnosis of a predisposition to arrhythmias. No mention was made, however, of the fact that in the hereditary prolonged Q-T syndromes, T waves with abnormal morphology are commonly found on the standard electrocardiogram (ECG),1 and these can be a helpful pointer to the diagnosis. The figure illustrates the ECG of a 12-year-old girl with Romano-Ward syndrome. These waves have been described as biphasic, bifid, or notched and may also be variably inverted. This abnormality is often much more striking at first glance than the prolongation of the Q-T interval, which may only become apparent measurement
after careful
measurement
PJ. Idiopathic long QT syndrome. Progress and questions. Am Heart J 1985; 109: 399-415. 2. Ahnve S. QT interval prolongation in acute myocardial infarction Eur Heart J 1985,6 (suppl D): 85-95. 3 James TN, Froggatt P, Atkinson WJ, et al. Observations on the pathophysiology of the long QT syndromes with special reference to the neuropathology of the heart. Circulation 1978, 57: 1221-31.
and correction with Bazett’s formula.
SCREENING FOR EARLY OVARIAN CANCER
Sip,—Professor Campbell and colleagues (Mar 26, p 710) report preliminary analysis of ultrasound screening for ovarian cancer. They acknowledge that the specificity of the screen was low, but suggest that the high detection rate and predictive value of a negative result "constitute the most important criteria for the evaluation of any screen for a lethal disease". As their screening their
programme detected all 5 cases of ovarian cancer which occurred in the study populaton during up to 2-years’ follow-up, they conclude that ultrasound is "acceptable and effective". Although high sensitivity is one essential attribute of a screen for cancer, other equally important criteria must be satisfied before a test becomes acceptable. Campbell et al report a specificity of 94-6% and that there was no evidence of morbidity or mortality among the 305 patients (300 false positives) who underwent laparoscopy or laparotomy. They did not, however, consider the psychological morbidity associated with recall for investigation of a positive screening test or the morbidity of laparoscopy or laparotomy even when uncomplicated. In addition the complication rate of diagnostic laparoscopy is 29-9/1000 (major complication rate 3-9/1000).’ The annual incidence of ovarian cancer among women over 45 years in the UK is 40/100000.2 If these figures are accurate a test with 964 specificity used to screen 100 000 women over 45 years of age would detect 40 cases (assuming 100% sensitivity) and produce 5398 false positive results requiring diagnostic surgery. Apart from the cost implications and the difficulty of persuading clinicians to act on a test with such a low positive predictive value, this would result in over 150 complications (21 major), if all patients with positive results were subjected to laparoscopy. Unless the specificity of ultrasound can be improved or benign ovarian tumours are shown to have malignant potential our contention (Feb 6, p 268) that ultrasound alone is unacceptable as a screen for ovarian cancer remains valid. London Hospital, London El 1BB
IAN
JACOBS
1 Chamberlain
G, Brown JC, eds. Gynaecological laparoscopy. the report of the Working Party of the Confidential Enquiry in Gynaecological Laparoscopy. London Royal College of Obstetricians and Gynaecologists, 1978 2 OPCS cancer statistics, registrations. Cases of diagnosed cancer registered in England and Wales London: HM Stationery Office, 1983.
V3 Abnormal T
waves
in
case
of hereditary long
Q-T syndrome.
SiR,—Jacobs et ap.2 reported a sensitivity and specificity of 100% for identifying early ovarian cancer with a combination of serum CA-125 over 30 U/ml, positive vaginal examination, and abnormal pelvic ultrasound. However, because of the insensitivity of vaginal examination all subjects with CA-125 over 30 U/ml (31/1010) were examined by ultrasound. 3 were abnormal and were operated on, but only 1 had ovarian cancer-a positive predictive value (PPV)
arrhythmia
same treatment.
Torsade de pointes related to Q-T prolongation may be a cause of ventricular arrhythmias during hypothyroidism, as demonstrated in our patient and in the case reported by Kumar et al.2 However, these two patients had secondary hypothyroidism due to panhypopituitarism. By contrast, the case reported by Guthrie et aP had peripheral hypothyroidism. Whether the association with other pituitary deficiencies increases the risk of torsade de pointes in Q-T interval prolongation due to hypothyroidism deserves further
The mechanism is said to be differing repolarisation times in different areas of the ventricle. A cellular defect would therefore have to be patchy to produce this effect. In ischaemic heart disease, when similar changes are found,2 sympathetic imbalance is at least as likely a cause as the myocardial damage. Similarly in alcoholic heart disease, an autonomic neuropathy could be the explanation for
Q-T prolongation. In the hereditary long Q-T syndromes, necropsy studies have failed to demonstrate a consistent abnormality, although James et al have described inflammation or degeneration of the intracardiac nerves
and sinoatrial node.3 There
are
several
reasons
for
supposing, therefore, that the underlying abnormality may be an imbalance of sympathetic innervation rather than a myocardial cellular defect, at least on current evidence. Woodend General Hospital, Aberdeen AB9 2YS
study.
JOHN C. S. DEAN
1. Schwartz
CHARLES EIFERMAN PHILIPPE CHANSON ARIEL COHEN JEAN LUBETZKI
Hôpital Lariboisière, 75475 Paris, France
1. Guthrie GP
Jr, Hunsaker JC, O’Connor WN. Sudden death
N Engl J Med 1987; 317: 1291. 2. Kumar A, Bhandari AK, Rahimtoola SH Torsade prolongation in association with hypothyroidism.
in
hypothyroidism.
de pointes and marked QT Ann Intern Med 1987; 106:
712-13.
T WAVES IN LONG Q-T SYNDROMES
SIR,-Dr Attwell and Dr Lee (May 21, p 1136) emphasise the of the corrected Q-T interval and its variation with heart rate in the diagnosis of a predisposition to arrhythmias. No mention was made, however, of the fact that in the hereditary prolonged Q-T syndromes, T waves with abnormal morphology are commonly found on the standard electrocardiogram (ECG),1 and these can be a helpful pointer to the diagnosis. The figure illustrates the ECG of a 12-year-old girl with Romano-Ward syndrome. These waves have been described as biphasic, bifid, or notched and may also be variably inverted. This abnormality is often much more striking at first glance than the prolongation of the Q-T interval, which may only become apparent measurement
after careful
measurement
PJ. Idiopathic long QT syndrome. Progress and questions. Am Heart J 1985; 109: 399-415. 2. Ahnve S. QT interval prolongation in acute myocardial infarction Eur Heart J 1985,6 (suppl D): 85-95. 3 James TN, Froggatt P, Atkinson WJ, et al. Observations on the pathophysiology of the long QT syndromes with special reference to the neuropathology of the heart. Circulation 1978, 57: 1221-31.
and correction with Bazett’s formula.
SCREENING FOR EARLY OVARIAN CANCER
Sip,—Professor Campbell and colleagues (Mar 26, p 710) report preliminary analysis of ultrasound screening for ovarian cancer. They acknowledge that the specificity of the screen was low, but suggest that the high detection rate and predictive value of a negative result "constitute the most important criteria for the evaluation of any screen for a lethal disease". As their screening their
programme detected all 5 cases of ovarian cancer which occurred in the study populaton during up to 2-years’ follow-up, they conclude that ultrasound is "acceptable and effective". Although high sensitivity is one essential attribute of a screen for cancer, other equally important criteria must be satisfied before a test becomes acceptable. Campbell et al report a specificity of 94-6% and that there was no evidence of morbidity or mortality among the 305 patients (300 false positives) who underwent laparoscopy or laparotomy. They did not, however, consider the psychological morbidity associated with recall for investigation of a positive screening test or the morbidity of laparoscopy or laparotomy even when uncomplicated. In addition the complication rate of diagnostic laparoscopy is 29-9/1000 (major complication rate 3-9/1000).’ The annual incidence of ovarian cancer among women over 45 years in the UK is 40/100000.2 If these figures are accurate a test with 964 specificity used to screen 100 000 women over 45 years of age would detect 40 cases (assuming 100% sensitivity) and produce 5398 false positive results requiring diagnostic surgery. Apart from the cost implications and the difficulty of persuading clinicians to act on a test with such a low positive predictive value, this would result in over 150 complications (21 major), if all patients with positive results were subjected to laparoscopy. Unless the specificity of ultrasound can be improved or benign ovarian tumours are shown to have malignant potential our contention (Feb 6, p 268) that ultrasound alone is unacceptable as a screen for ovarian cancer remains valid. London Hospital, London El 1BB
IAN
JACOBS
1 Chamberlain
G, Brown JC, eds. Gynaecological laparoscopy. the report of the Working Party of the Confidential Enquiry in Gynaecological Laparoscopy. London Royal College of Obstetricians and Gynaecologists, 1978 2 OPCS cancer statistics, registrations. Cases of diagnosed cancer registered in England and Wales London: HM Stationery Office, 1983.
V3 Abnormal T
waves
in
case
of hereditary long
Q-T syndrome.
SiR,—Jacobs et ap.2 reported a sensitivity and specificity of 100% for identifying early ovarian cancer with a combination of serum CA-125 over 30 U/ml, positive vaginal examination, and abnormal pelvic ultrasound. However, because of the insensitivity of vaginal examination all subjects with CA-125 over 30 U/ml (31/1010) were examined by ultrasound. 3 were abnormal and were operated on, but only 1 had ovarian cancer-a positive predictive value (PPV)