Familial risk for endometriosis and its interaction with smoking, age at menarche and body mass index: a population-based cohort study among siblings

OBJECTIVE

To quantify familial risk of endometriosis among full siblings and examine interactions between family history and smoking, age at menarche or body mass index (BMI).

DESIGN, SETTING AND POPULATION

Population-based nationwide cohort study.

METHODS

Using data from the Korean National Health Insurance and Screening Programme databases on kinship, healthcare utilisation, lifestyle and anthropometrics, we identified 2 109 288 women with full siblings and their environmental risk factors from 2002 to 2018. Familial risks were estimated using Cox proportional-hazards models, represented as incidence risk ratios (IRR) with 95% CI. Interaction between family history and smoking, age at menarche or BMI were assessed on an additive scale.

MAIN OUTCOME MEASURES

IRR of endometriosis among women with and without affected siblings.

RESULTS

From 19 195 women with affected siblings, 1126 developed endometriosis with an incidence of 35.45/10 000 person-years. Familial risk of endometriosis with versus without affected siblings was increased to IRR 2.75 (95% CI 2.25-3.36), and the highest risk was with affected twins (IRR 6.98; 95% CI 4.19-11.62). Women with both a family history and either smoking, early menarche or low BMI had a significantly higher risk of endometriosis compared with the general population and can be regarded as a high-risk group, the IRRs were 4.28 (95% CI 2.43-7.55), 3.47 (95% CI 2.82-4.26) and 3.09 (95% CI 2.68-3.56), respectively. Substantial effect modification of the associations was noted by smoking and early menarche, as their combined risk with family history exceeded the sum of their individual risks, which was also statistically significant.

CONCLUSION

Genetic factors are the primary contributor to the familial aggregation of endometriosis. Significant gene-environment interaction exists between family history and smoking or early menarche.

Atenolol is not effective in reducing ventricular arrhythmia severity on exercise stress test in patients with catecholaminergic polymorphic ventricular tachycardia

 

Patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) are at risk for malignant ventricular arrhythmias during exercise and emotions which may lead to sudden cardiac death. Beta-blockers (BB) are the mainstay of therapy in patients with CPVT, but studies comparing the efficacy of different types of BB are scarce. Our objective was to determine the efficacy of different types of BB in reducing the ventricular arrhythmia (VA) severity on exercise stress test (EST) in patients with CPVT.

Data was derived from the International CPVT Registry, a large retrospective cohort study. We included patients who had an EST before (pre-EST) and after start of BB (post-EST). We divided the cohort into five groups based on the first prescribed BB and compared pre-EST and post-EST.

We included 428 patients (median age 18.5 [11.7–39.6] years, 240 (56.%) female), 155 (36.2%) probands) of whom 38 (8.9%) used atenolol, 131 (30.6%) bisoprolol, 82 (19.2%) metoprolol, 124 (29.0%) nadolol and 53 (12.4%) propranolol. Sex and history of aborted cardiac arrest were similar in all groups. The age at start of BB differed (p<0,001): patients using bisoprolol were oldest (35.0 [15.7–35.3]) while patients using propranolol were youngest (12.3 [8.8–24.9]). Median daily BB dose in mg/kg was: 1.0 [0.8–2.3] for atenolol, 0.06 [0.05–0.10] for bisoprolol, 0.9 [0.6–1.5] for metoprolol, 1.1 [0.9–1.6] for nadolol and 1.5 [1.1–2.8] for propranolol. Resting heart rate on pre-EST and post-EST was similar in all groups. Patients using metoprolol had a significantly higher maximum heart rate post-EST compared to nadolol and propranolol (161±18 vs 136±19 and 130±22 bpm, p=0,002 and p=0,001, respectively). The VA severity decreased significantly after BB (147 (37.9%) (non-sustained) ventricular tachycardia ((NS)VT) and 120 (30.9%) no or isolated ventricular premature beat (iVPB) pre-EST vs 46 (11.4%) (NS)VT and 184 (45.7%) iVPB post-EST, p<0,001). Examining the different groups, the VA severity decreased significantly after BB in all but atenolol (13 (40.6%) (NS)VT and 8 (25.0%) iVPB pre-EST vs 9 (25.0%) (NS)VT and 15 (41.7%) iVPB post-EST, p=0,103).

Based on these results we conclude that all beta-blockers except atenolol are effective in reducing the VA severity on EST in patients with CPVT.

Funding Acknowledgement

Type of funding source: Public grant(s) – EU funding. Main funding source(s): E-Rare Joint Transnational Call for Proposals 2015 “Improving Diagnosis and Treatment of Catecholaminergic Polymorphic Ventricular Tachycardia: Integrating Clinical and Basic Science”

Mutation-specific differences in arrhythmias and drug responses in CPVT patients: simultaneous patch clamp and video imaging of iPSC derived cardiomyocytes

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited cardiac disease characterized by arrhythmias under adrenergic stress. Mutations in the cardiac ryanodine receptor (RYR2) are the leading cause for CPVT. We characterized electrophysiological properties of CPVT patient-specific induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) carrying different mutations in RYR2 and evaluated effects of carvedilol and flecainide on action potential (AP) and contractile properties of hiPSC-CMs. iPSC-CMs were generated from skin biopsies of CPVT patients carrying exon 3 deletion (E3D) and L4115F mutation in RYR2. APs and contractile movement were recorded simultaneously from the same hiPSC-CMs. Differences in AP properties of ventricular like CMs were seen in CPVT and control CMs: APD90 of both E3D (n = 20) and L4115F (n = 25) CPVT CMs was shorter than in control CMs (n = 15). E3D-CPVT CMs had shortest AP duration, lowest AP amplitude, upstroke velocity and more depolarized diastolic potential than controls. Adrenaline had positive and carvedilol and flecainide negative chronotropic effect in all hiPSC CMs. CPVT CMs had increased amount of delayed after depolarizations (DADs) and early after depolarizations (EADs) after adrenaline exposure. E3D CPVT CMs had the most DADs, EADs, and tachyarrhythmia. Discordant negatively coupled alternans was seen in L4115F CPVT CMs. Carvedilol cured almost all arrhythmias in L4115F CPVT CMs. Both drugs decreased contraction amplitude in all hiPSC CMs. E3D CPVT CMs have electrophysiological properties, which render them more prone to arrhythmias. iPSC-CMs provide a unique platform for disease modeling and drug screening for CPVT. Combining electrophysiological measurements, we can gain deeper insight into mechanisms of arrhythmias.

Electron Solvation and the Unique Liquid Structure of a Mixed-Amine Expanded Metal: The Saturated Li-NH3 -MeNH2 System

Metal-amine solutions provide a unique arena in which to study electrons in solution, and to tune the electron density from the extremes of electrolytic through to true metallic behavior. The existence and structure of a new class of concentrated metal-amine liquid, Li-NH₃ -MeNH₂ , is presented in which the mixed solvent produces a novel type of electron solvation and delocalization that is fundamentally different from either of the constituent systems. NMR, ESR, and neutron diffraction allow the environment of the solvated electron and liquid structure to be precisely interrogated. Unexpectedly it was found that the solution is truly homogeneous and metallic. Equally surprising was the observation of strong longer-range order in this mixed solvent system. This is despite the heterogeneity of the cation solvation, and it is concluded that the solvated electron itself acts as a structural template. This is a quite remarkable observation, given that the liquid is metallic.

The return of unexpected research results in a biobank study and referral to health care for heritable long QT syndrome

BACKGROUND

In this study, we examined how biobank study participants, who were found to have long QT syndrome (LQTS), a potentially life-threatening but treatable cardiac arrhythmia condition, experienced the process of disclosure of unexpected results and referral to health care.

METHODS

All 27 subjects with a LQTS mutation finding were asked to complete a questionnaire. Four participants did not uptake the re-testing and 5 others did not respond to the questionnaire. We received 17 questionnaires from 6 males and 11 females, aged 46-82; 5 of them were also willing to participate in qualitative interviews.

RESULTS

Of the respondents, 16/17 had experienced the process of receiving the results as positive and useful, especially if they had had symptoms. One respondent experienced the process negatively due to concerns related to informing her children. All respondents felt that genetic results should be reported back to the participants, while 2 indicated that this should occur only in the case of treatable conditions. Respondents had informed all of their children about the genetic condition, except 2 minors.

CONCLUSIONS

The respondents from a population biobank study who were informed about an unexpected genetic finding evaluated this process as mainly positive. They considered that delivering genetic information about a life-threatening but actionable condition has more beneficial than adverse consequences. The feedback policy for biobanks should include how and who is informed, advise treatment or care pathways for actionable findings, and it should also include suitable options for those who do not want to know about such findings.

Common candidate gene variants are associated with QT interval duration in the general population

OBJECTIVES

QT interval prolongation is associated with increased risk of sudden cardiac death at the population level. As 30-40% of the QT-interval variability is heritable, we tested the association of common LQTS and NOS1AP gene variants with QT interval in a Finnish population-based sample.

METHODS

We genotyped 12 common LQTS and NOS1AP genetic variants in Health 2000, an epidemiological sample of 5043 Finnish individuals, using Sequenom MALDI-TOF mass spectrometry. ECG parameters were measured from digital 12-lead ECGs and QT intervals were adjusted for age, gender and heart rate with a nomogram (Nc) method derived from the present study population.

RESULTS

The KCNE1 D85N minor allele (frequency 1.4%) was associated with a 10.5 ms (SE 1.6) or 0.57 SD prolongation of the adjusted QT(Nc) interval (P=3.6 x 10(-11)) in gender-pooled analysis. In agreement with previous studies, we replicated the association with QT(Nc) interval with minor alleles of KCNH2 intronic SNP rs3807375 [1.6 ms (SE 0.4) or 0.08 SD, P=4.7 x 10(-5)], KCNH2 K897T [-2.6 ms (SE 0.5) or -0.14 SD, P=2.1 x 10(-7)] and NOSA1P variants including rs2880058 [4.0 ms (SE 0.4) or 0.22 SD, P=3.2 x 10(-24)] under additive models.

CONCLUSIONS

We demonstrate that each additional copy of the KCNE1 D85N minor allele is associated with a considerable 10.5 ms prolongation of the age-, gender- and heart rate-adjusted QT interval and could thus modulate repolarization-related arrhythmia susceptibility at the population level. In addition, we robustly confirm the previous findings that three independent KCNH2 and NOSA1P variants are associated with adjusted QT interval.

Passive transfer of immunoglobulin G and preweaning health in Holstein calves fed a commercial colostrum replacer

The objective of this study was to describe passive transfer of IgG and preweaning health in newborn calves fed a commercially available plasma-derived colostrum replacement (CR) product or maternal colostrum (MC). Twelve commercial Holstein dairy farms enrolled singleton newborn heifer calves to be fed fresh MC (n = 239 calves) or one dose of CR containing 125 g of Ig (n = 218 calves) as the first colostrum feeding. For 7 of these farms that routinely provided a second feeding of 1.9 L of MC to their calves 8 to 12 h after the first colostrum feeding, calves assigned to the CR treatment group were offered a second feeding consisting of 1.9 L of commercial milk replacer supplemented with one dose of a commercially available plasma-derived colostrum supplement, containing 45 g of Ig per dose, 8 to 12 h after the first colostrum feeding. A blood sample was collected from all calves between 1 to 8 d of age for serum IgG and total protein (TP) determination, and records of all treatment and mortality events were collected until weaning. Serum IgG and TP concentrations were significantly higher in calves fed MC (IgG = 14.8 +/- 7.0 mg/mL; TP = 5.5 +/- 0.7 g/dL) compared with calves fed CR (IgG = 5.8 +/- 3.2 mg/mL; TP = 4.6 +/- 0.5 g/dL). The proportion of calves with failure of passive transfer (serum IgG <10.0 mg/mL) was 28.0 and 93.1% in the MC and CR treatment groups, respectively. Though a trend was present, the proportion of calves treated for illness was not statistically different for calves fed MC (51.9%) vs. CR (59.6%). Total number of days treated per calf (MC = 1.7; CR = 2.0), treatment costs per calf (MC = $10.84; CR = $11.88), and proportion of calves dying (MC = 10.0%; CR = 12.4%) was not different between the 2 colostrum treatment groups. The mean serum total protein concentration predictive of successful passive transfer (serum IgG = 10 mg/mL) was 5.0 g/dL in calves fed MC or CR. Long-term follow-up of these calves (to maturity) is ongoing to describe the effects of feeding CR on longevity, productivity, risk for Johne's disease, and economics.

Response of the QT interval to mental and physical stress in types LQT1 and LQT2 of the long QT syndrome

OBJECTIVE

To study and compare the effects of mental and physical stress on long QT syndrome (LQTS) patients.

DESIGN

Case-control study.

MAIN OUTCOME MEASURES

QT intervals were measured from lead V3. Serum potassium and plasma catecholamine concentrations were also monitored.

PATIENTS

16 patients with type 1 LQTS (LQT1), 14 with type 2 LQTS (LQT2), both groups asymptomatic, and 14 healthy control subjects.

INTERVENTIONS

Three types of mental stress tests and a submaximal exercise stress test.

RESULTS

Heart rate responses to mental stress and exercise were similar in all groups. During mental stress, the mean QT interval shortened to a similar extent in controls (-29 ms), LQT1 patients (-34 ms), and LQT2 patients (-30 ms). During exercise, the corresponding QT adaptation to exercise stress was more pronounced (p < 0.01) in healthy controls (-47 ms) than in LQT1 (-38 ms) or LQT2 patients (-38 ms). During exercise changes in serum potassium concentrations were correlated to changes in QT intervals in controls, but not in LQTS patients. LQT1 and LQT2 patients did not differ in serum potassium, catecholamine or heart rate responses to mental or physical stress.

CONCLUSIONS

QT adaptation to mental and exercise stress in healthy people and in patients with LQTS is different. In healthy people QT adaptation is more sensitive to physical than to mental stress while no such diverging pattern was seen in asymptomatic LQTS patients.

Response of the QT interval to mental and physical stress in types LQT1 and LQT2 of the long QT syndrome

OBJECTIVE

To study and compare the effects of mental and physical stress on long QT syndrome (LQTS) patients.

DESIGN

Case–control study.

MAIN OUTCOME MEASURES

QT intervals were measured from lead V3. Serum potassium and plasma catecholamine concentrations were also monitored.

PATIENTS

16 patients with type 1 LQTS (LQT1), 14 with type 2 LQTS (LQT2), both groups asymptomatic, and 14 healthy control subjects.

INTERVENTIONS

Three types of mental stress tests and a submaximal exercise stress test.

RESULTS

Heart rate responses to mental stress and exercise were similar in all groups. During mental stress, the mean QT interval shortened to a similar extent in controls (–29 ms), LQT1 patients (–34 ms), and LQT2 patients (–30 ms). During exercise, the corresponding QT adaptation to exercise stress was more pronounced (p < 0.01) in healthy controls (–47 ms) than in LQT1 (–38 ms) or LQT2 patients (–38 ms). During exercise changes in serum potassium concentrations were correlated to changes in QT intervals in controls, but not in LQTS patients. LQT1 and LQT2 patients did not differ in serum potassium, catecholamine or heart rate responses to mental or physical stress.

CONCLUSIONS

QT adaptation to mental and exercise stress in healthy people and in patients with LQTS is different. In healthy people QT adaptation is more sensitive to physical than to mental stress while no such diverging pattern was seen in asymptomatic LQTS patients.

A founder mutation of the potassium channel KCNQ1 in long QT syndrome: implications for estimation of disease prevalence and molecular diagnostics

OBJECTIVES

We took advantage of the genetic isolate of Finns to characterize a common long QT syndrome (LQTS) mutation, and to estimate the prevalence of LQTS.

BACKGROUND

The LQTS is caused by mutations in different ion channel genes, which vary in their molecular nature from family to family.

METHODS

The potassium channel gene KCNQ1 was sequenced in two unrelated Finnish patients with Jervell and Lange-Nielsen syndrome (JLNS), followed by genotyping of 114 LQTS probands and their available family members. The functional properties of the mutation were studied using a whole-cell patch-damp technique.

RESULTS

We identified a novel missense mutation (G589D or KCNQ1-Fin) in the C-terminus of the KCNQ1 subunit. The voltage threshold of activation for the KCNQ1-Fin channel was markedly increased compared to the wild-type channel. This mutation was present in homozygous form in two siblings with JLNS, and in heterozygous form in 34 of 114 probands with Romano-Ward syndrome (RWS) and 282 family members. The mean (+/- SD) rate-corrected QT intervals of the heterozygous subjects (n = 316) and noncarriers (n = 423) were 460 +/- 40 ms and 410 +/- 20 ms (p < 0.001), respectively.

CONCLUSIONS

A single missense mutation of the KCNQ1 gene accounts for 30% of Finnish cases with LQTS, and it may be associated with both the RWS and JLNS phenotypes of the syndrome. The relative enrichment of this mutation most likely represents a founder gene effect. These circumstances provide an excellent opportunity to examine how genetic and nongenetic factors modify the LQTS phenotype.

Mutations of the cardiac ryanodine receptor (RyR2) gene in familial polymorphic ventricular tachycardia

BACKGROUND

Familial polymorphic ventricular tachycardia is an autosomal-dominant, inherited disease with a relatively early onset and a mortality rate of approximately 30% by the age of 30 years. Phenotypically, it is characterized by salvoes of bidirectional and polymorphic ventricular tachycardias in response to vigorous exercise, with no structural evidence of myocardial disease. We previously mapped the causative gene to chromosome 1q42-q43. In the present study, we demonstrate that patients with familial polymorphic ventricular tachycardia have missense mutations in the cardiac sarcoplasmic reticulum calcium release channel (ryanodine receptor type 2 [RyR2]).

METHODS AND RESULTS

In 3 large families studied, 3 different RyR2 mutations (P2328S, Q4201R, V4653F) were detected and shown to fully cosegregate with the characteristic arrhythmic phenotype. These mutations were absent in the nonaffected family members and in 100 healthy controls. In addition to identifying 3 causative mutations, we identified a number of single nucleotide polymorphisms that span the genomic structure of RyR2 and will be useful for candidate-based association studies for other arrhythmic disorders.

CONCLUSIONS

Our data illustrate that mutations of the RyR2 gene cause at least one variety of inherited polymorphic tachycardia. These findings define a new entity of disorders of myocardial calcium signaling.

Molecular genetics of the long QT syndrome: two novel mutations of the KVLQT1 gene and phenotypic expression of the mutant gene in a large kindred

At least three different gene loci were recently shown to account for the long QT syndrome (LQTS), a monogenic disorder with altered myocardial repolarization and occurrence of life-threatening cardiac arrhythmias. We screened 44 unrelated probands for mutations of the gene encoding the cardiac potassium channel KVLQT1 using single-strand conformational polymorphism (SSCP) and subsequent DNA sequencing. Two different mutations, T182I and D188N, were identified in two separate pedigrees. Cosegregation of the mutation with the disease phenotype was evident in both families. No mutations were identified at codon 212, previously suggested to represent a mutational hot spot of the KVLQT1 channel, in any of the 44 probands. The large pedigree with the D188N mutation (30 affected and 43 nonaffected individuals) permitted an analysis of expression of the mutant gene in its documented carriers. Although the mean (+/-SD) QTc interval was markedly longer in affected (484+/-38 ms) than in nonaffected individuals (406+/-27 ms, P < 0.001), there was a marked overlapping of individual values in these two groups. QTc values in symptomatic and asymptomatic carriers of the mutant gene were not significantly different. In conclusion, we have identified two novel mutations of the KVLQT1 component of a cardiac potassium channel. Our data support the functional significance of the pore-S6 domain of this membrane protein and emphasize the diagnostic usefulness of DNA analyses in families with LQTS.

Homozygosity for a HERG potassium channel mutation causes a severe form of long QT syndrome: identification of an apparent founder mutation in the Finns

OBJECTIVES

We studied the clinical characteristics and molecular background underlying a severe phenotype of long QT syndrome (LQTS).

BACKGROUND

Mutations of cardiac ion channel genes cause LQTS, manifesting as increased risk of ventricular tachycardia and sudden death.

METHODS

We studied two siblings showing prolonged QT intervals corrected for heart rate (QTc), their asymptomatic parents with only marginally prolonged QTc intervals and their family members. The potassium channel gene HERG was screened for mutations by deoxyribonucleic acid sequencing, and the electrophysiologic consequences of the mutation were studied in vitro using the whole-cell patch-clamp technique.

RESULTS

A novel missense mutation (L552S) in the HERG channel, present in the homozygous state in the affected siblings and in the heterozygous state in their parents, as well as in 38 additional subjects from six LQTS families, was identified. One of the homozygous siblings had 2:1 atrioventricular block immediately after birth, and died at the age of four years after experiencing unexplained hypoglycemia. The other sibling had an episode of torsade de pointes at the age of two years. The mean QTc interval differed significantly (p < 0.001) between heterozygous symptomatic mutation carriers (500 +/- 59 ms), asymptomatic mutation carriers (452 +/- 34 ms) and noncarriers (412 +/- 23 ms). When expressed in vitro, the HERG-L552S formed functional channels with increased activation and deactivation rates.

CONCLUSIONS

Our data demonstrate that homozygosity for a HERG mutation can cause a severe cardiac repolarization disorder without other phenotypic abnormalities. Absence of functional HERG channels appears to be one cause for intrauterine and neonatal bradycardia and 2:1 atrioventricular block.

Survey of the coding region of the HERG gene in long QT syndrome reveals six novel mutations and an amino acid polymorphism with possible phenotypic effects

Analysis of the entire coding region of the HERG gene of 39 Finnish LQTS patients revealed eight mutations, six of which are hitherto unreported. All these mutations are located in the evolutionarily conserved regions of HERG, including the transmembrane domains (P451L, Y569H, 1631delAG, G584S, G601S, T613M) and the cytoplasmic N-terminus (453delC, R176W) of the channel. Our present and earlier results suggest that the LQT2 subtype accounts for approximately 20-30% of LQTS cases in Finland. We also report the first common amino acid polymorphism (K897T) of the HERG channel, with allele frequencies of 0.84 and 0.16. Investigation of 170 genetically homogenous LQT1 patients suggests that this polymorphism may influence QT interval in female individuals.

Arrhythmic disorder mapped to chromosome 1q42-q43 causes malignant polymorphic ventricular tachycardia in structurally normal hearts

OBJECTIVES

The purpose of this study was to provide clinical and anatomical characteristics as well as genetic background of a malignant arrhythmogenic disorder.

BACKGROUND

An inherited autosomally dominant cardiac syndrome causing stress-induced polymorphic ventricular tachycardia and syncope in the absence of structural myocardial changes was detected in two families.

METHODS

Two unrelated families with six victims of sudden death and 51 living members were evaluated. Resting and exercise electrocardiograms (ECG), echocardiography, magnetic resonance imaging (MRI), cineangiography, microscopic examination of endomyocardial biopsies and a drug testing with a class IC antiarrhythmic agent flecainide were performed. A genetic linkage analysis was carried out to map the gene locus.

RESULTS

Of the 24 affected individuals, 10 had succumbed with six cases of sudden death, and 14 survivors showed evidence of disease. Exercise stress test induced ventricular bigeminy or polymorphic ventricular tachycardia in affected individuals. Three children initially examined before 10 years of age developed arrhythmias during a four-year follow-up. Resting ECGs were normal in affected subjects except a slight prolongation of the QT intervals adjusted for heart rate (QTc) (430 +/- 18 vs. 409 +/- 19 ms, affected vs. nonaffected, p < 0.01). Administration of flecainide did not induce ECG abnormalities encountered in familial idiopathic ventricular fibrillation. Ventricular volumes, contractility and wall measurements were normal by echocardiography, right ventricular cineangiography and MRI. Histopathological examination showed no fibrosis or fatty infiltration. The cumulative cardiac mortality by the age of 30 years was 31%. The disease locus was assigned to chromosome 1q42-q43, with a maximal pairwise lod score of 4.74 in the two families combined. Only one heterozygous carrier was clinically unaffected suggesting high disease penetrance in adulthood.

CONCLUSIONS

A distinct cardiac disorder linked to chromosome 1q42-q43 causes exercise-induced polymorphic ventricular tachycardia in structurally normal hearts and is highly malignant. Delayed clinical manifestation necessitates repeated exercise electrocardiography to assure diagnosis in young individuals of the families.

Sinus node function and ventricular repolarization during exercise stress test in long QT syndrome patients with KvLQT1 and HERG potassium channel defects

OBJECTIVES

This study was performed to evaluate the QT interval and heart rate responses to exercise and recovery in gene and mutation type-specific subgroups of long QT syndrome (LQTS) patients.

BACKGROUND

Reduced heart rate and repolarization abnormalities are encountered among long QT syndrome (LQTS) patients. The most common types of LQTS are LQT1 and LQT2.

METHODS

An exercise stress test was performed in 23 patients with a pore region mutation and in 22 patients with a C-terminal end mutation of the cardiac potassium channel gene causing LQT1 type of long QT syndrome (KVLQT1 gene), as well as in 20 patients with mutations of the cardiac potassium channel gene causing LQT2 type of long QT syndrome (HERG gene) and in 33 healthy relatives. The QT intervals were measured on electrocardiograms at rest and during and after exercise. QT intervals were compared at similar heart rates, and rate adaptation of QT was studied as QT/heart rate slopes.

RESULTS

In contrast to the LQT2 patients, achieved maximum heart rate was decreased in both LQT1 patient groups, being only 76 +/- 5% of predicted in patients with pore region mutation of KvLQT1. The QT/heart rate slopes were significantly steeper in LQT2 patients than in controls during exercise. During recovery, the QT/heart rate slopes were steeper in all LQTS groups than in controls, signifying that QT intervals lengthened excessively when heart rate decreased. At heart rates of 110 or 100 beats/min during recovery, all LQT1 patients and 89% of LQT2 patients had QT intervals longer than any of the controls.

CONCLUSIONS

LQT1 is associated with diminished chronotropic response and exaggerated prolongation of QT interval after exercise. LQT2 patients differ from LQT1 patients by having marked QT interval shortening and normal heart rate response to exercise. Observing QT duration during recovery enhances the clinical diagnosis of these LQTS types.

Neuroleptanesthesia: current status

PURPOSE

To review the current status and possible future of neuroleptanalgesia/anesthesia, techniques that may be nearly extinct.

SOURCE

Articles from 1966 to present were obtained from the Current Science and Medline databases. Search terms include neurolepananalgesia/anesthesia, conscious sedation, droperidol, benzodiazepines, propofol, ketamine, and opioids. Information and abstracts obtained from meetings on this topic helped complete the collection of information.

PRINCIPAL FINDINGS

Droperidol/fentanyl may still be clinically indicated in the management of surgical seizure therapy for electrocorticography. However, the high incidence of post-operative sedation and restlessness discourage its use for other surgical or diagnostic procedures. Many surgical interventions, once thought ideally suited for neuroleptic agents, now meet better success with newer medications. The use of midazolam and/or propofol, in association with newer opioids, provides ideal anesthetic combinations.

CONCLUSION

The advantages of newer anesthetic agents have redefined the clinical indications for neuroleptanesthesia. In routine modern anesthesia, anxiolysis, sedation, and/or analgesia is better provided, with quicker recovery, by the new pharmacokinetic and pharmacodynamic characteristics of recent medications than by the neuroleptic component of neuroleptanesthesia.

Evaluation of QT interval duration and dispersion and proposed clinical criteria in diagnosis of long QT syndrome in patients with a genetically uniform type of LQT1

OBJECTIVES

This study investigated the ability of QT duration, QT dispersion (QTD) and clinical diagnostic criteria to correctly identify genetically documented LQT1 type long QT syndrome (LQTS) patients, and to separate symptomatic and asymptomatic LQT1 patients.

BACKGROUND

Ventricular repolarization has played an essential role both in diagnosis and risk assessment of LQTS. Today, molecular genetic techniques permit unequivocal identification of many LQTS patients.

METHODS

QT interval and QTD in 12 symptomatic and 18 asymptomatic LQT1 patients and their 43 healthy relatives were evaluated. The sensitivity and specificity of upper normal limits of QT interval, two QT interval adjustment methods (Bazett's and Fridericia's formulas), and the proposed clinical criteria for LQTS were assessed. Occurrence of a mutant (D188N) KVLQT1 gene was considered as the basis of classification into affected and nonaffected individuals.

RESULTS

Diagnostic sensitivity and specificity values were 90% and 88% using Bazett's formula, and 80% and 100% using Fridericia's cubic root formula or upper normal limits for QT interval. Suggested diagnostic criteria for LQTS reached 100% specificity, but 47% of the DNA-documented LQT1 patients were classified into the category of low or intermediate probability of LQTS. QT interval and heart rate did not differ between symptomatic (464 +/- 47 ms, 70 +/- 9 min(-1)) and asymptomatic 460 +/- 41 ms, 65 +/- 13 min(-1)) LQT1 patients. QTD was increased in symptomatic LQT1 patients compared to unaffected relatives (66 +/- 48 vs. 37 +/- 15 ms, p = 0.02), but symptomatic patients LQT1 did not differ from asymptomatic (45 +/- 19 ms).

CONCLUSIONS

Not all LQT1 patients can be distinguished from healthy relatives by assessment of QT duration or clinical criteria. Presence of LQT1 gene can carry the risk of cardiac events even with no or only marginal prolongation of QT interval.

Effects of epinephrine and phenylephrine on QT interval dispersion in congenital long QT syndrome

OBJECTIVES

Measurement of QT interval dispersion during pharmacologic adrenergic stimulation was used to assess the effect of alpha- and beta-adrenergic stimulation on arrhythmic vulnerability in familial long QT syndrome (LQTS).

BACKGROUND

Nonhomogeneity in the ventricular action potential duration causes electrical instability leading to life-threatening ventricular arrhythmias and is markedly increased in LQTS. QT interval dispersion measured from the electrocardiogram (ECG) can be used as an index of nonhomogeneous ventricular repolarization.

METHODS

Sixteen symptomatic patients with LQTS and nine healthy control subjects were examined at baseline and during epinephrine (mainly beta-adrenergic agonist, 0.05 microg/kg body weight per min) and phenylephrine infusions (alpha-adrenergic agonist, mean 1.4 microg/kg per min). QT interval dispersion was determined from a 12-lead ECG as interlead range and coefficient of variation measured to the end (QTend) and apex (QTapex) of the T wave.

RESULTS

At baseline QTend dispersion was greater in patients with LQTS compared with control subjects (mean [+/-SD] 68+/-34 vs. 36+/-7 ms, p=0.001). QTend dispersion was markedly increased in patients with LQTS by use of epinephrine (from 68+/-34 to 90+/-36 ms, p=0.002), but remained unchanged in control subjects. Phenylephrine did not affect QT dispersion in either group (all p=NS). Atrial pacing to achieve comparable heart rates during baseline and epinephrine and phenylephrine infusions did not influence the magnitude of QT dispersion in either group. QTapex dispersion analysis gave congruent results.

CONCLUSIONS

Epinephrine but not phenylephrine increased QT dispersion, suggesting that beta-adrenergic stimulation provokes arrhythmias in patients with LQTS by aggravating nonhomogeneity of ventricular repolarization, whereas alpha-adrenergic stimulation is less important for arrhythmic vulnerability. The results also suggest that rapid pacing may not reduce vulnerability to arrhythmias in congenital LQTS.

Rate adaptation of QT intervals during and after exercise in children with congenital long QT syndrome

OBJECTIVES

To improve the diagnostic criteria of the congenital long QT syndrome in borderline cases we examined rate adaptation of ventricular repolarization phases during exercise and subsequent recovery in children with the long QT syndrome and controls.

METHODS

Nineteen children with definite long QT syndrome and 19 healthy controls underwent exercise testing. QT intervals were measured to the apex (early QT), to the end (total QT) and from apex to the end of the T wave (late QT) at heart rates from 90 by steps of 10 to 150 beats, min-1.

RESULTS

In 11/19 long QT syndrome patients (61%) and 2/19 controls (12%) the total QT lengthened during the recovery phase compared with exercise (P = 0.005) at the lowest comparable heart rate. No difference was found between the groups during exercise. The sensitivity of rate adaptation of repolarization intervals was analysed by calculating linear regression slopes relating the QT intervals to the heart rates. During recovery, slopes relating the total QT to heart rate were steeper in long QT syndrome patients than those in controls (-2.50 +/- 0.82 vs -1.79 +/- 0.47, P = 0.003). Total QT/heart rate slopes differed between exercise and recovery phases in the long QT syndrome group only (-1.77 +/- 0.71 vs 2.50 +/- 0.82, P = 0.009). In long QT syndrome patients, the difference in total QT/heart rate slopes was mainly because the late QT/heart rate slopes indicating inhomogeneity of repolarization were steeper during recovery (-1.27 +/- 0.74) than during exercise (-0.46 +/- 0.29, P < 0.0001).

CONCLUSIONS

After exercise in long QT syndrome children the QT interval lengthens abnormally and inhomogeneity of repolarization increases. Evaluation of the QT interval, and especially its late portion after exercise, may help in establishing the diagnosis of long QT syndrome.

Linkage of the long QT syndrome to the short arm of chromosome 11: use of five highly polymorphic markers towards more detailed localization of the mutant gene

The long QT syndrome is an autosomally dominantly inherited cardiac disorder characterized by abnormalities of myocardial repolarization, exercise- or stress-related syncopal attacks and risk of sudden death due to cardiac arrhythmias. Genetic linkage studies have defined three LQT loci on chromosomes 11p15.5, 3q21-24 and 7p35-36. We performed linkage analyses in three Finnish LQT families using five amplifiable markers assigned to chromosome 11p15. By multipoint linkage analyses we obtained a maximal lod score of 5.503, suggesting that the LQT1 locus maps between D11S922 and D11S1338 on chromosome 11. Our data provide a step towards closer definition of the exact borderlines of the LQT1 locus in chromosome 11 and demonstrate markers with high utility in identification of gene carriers in the affected families.

Aminosulfonic acid buffer preserves myocardium during prolonged ischemia

Prevention of myocardial acidosis during global ischemia in operative cardiopreservation was explored in two series of dogs where acid-base control was the only variable. A specifically designed aminosulfonic acid buffer composition, 3:1 molar equivalents NaMOPS to HEPES, 0.2 mol/L, was compared with NaHCO3 (pH 8). Dissolved in standard cardioplegic solution it was given every 30 minutes by coronary infusion at 20 degrees C during 3 hours of global ischemia. Glass electrode intramyocardial pH, adenosine triphosphate (ATP) level, left ventricular contractility (Dp/Dt) and compliance (-Dp/Dt), and other cardiovascular parameters were measured frequently throughout ischemia and for 75 minutes thereafter. In the buffer group (n = 6) myocardial pH remained above entry levels throughout the study period, adenosine triphosphate level remained normal during ischemia, and Dp/Dt and -Dp/Dt at 75 minutes of reperfusion were above entry levels. In the NaHCO3 group (n = 6) pH declined and remained depressed throughout ischemia, adenosine triphosphate level fell steadily and significantly throughout the experiment, and Dp/Dt and -Dp/Dt never regained entry levels. The difference in each parameter between the two groups was statistically significant (p < 0.05). We conclude that control of myocardial acid-base equilibrium alone during global ischemia will preserve myocardial function and minimize reperfusion injury.

Ultrasonic beam-plotting with very small spheres

A method of pulse-echo ultrasonic beam plotting is described. It differs from traditional pulse-echo beam plotting in that the ultrasonic pulses are scattered off a totally isolated sphere rather than a sphere suspended on a wire. The method also allows extremely small spheres to be used thus providing greater resolution. It is demonstrated that pulse-echo beam plotting using spheres of different size produces different iso-echo amplitude curves.

Quality control of perfusion: monitoring venous blood oxygen tension to prevent hypoxic acidosis

The long-held belief that venous oxygen tension mirrored tissue oxygen tension became suspect in the 1960s when new instrumentation consistently showed that tissue oxygen tension was 10 to 30 torr less than venous oxygen tension. Moreover, a countercurrent of oxygen exchange between terminal arteries and veins was shown to exist. Despite this conflict in scientific theory, however, monitoring venous oxygen tension as a means to control hypothermic cardiopulmonary bypass has been repeatedly urged, since myocardial acidosis is clearly extremely detrimental. This study of the relationship between venous oxygen tension during hypothermic bypass and a concurrent increment in lactacidemia yields strong objective evidence to support the use of on-line venous oxygen tension monitoring to guide perfusion. In a random series of 36 patients, venous blood samples were drawn at five preselected intervals during operation and were analyzed for pH, carbon dioxide tension, oxygen tension, lactic acid, hematocrit, and base excess. Analysis of the data revealed that venous pH and base excess showed no correlation to venous oxygen tension. However, lactic acid showed a strong correlation with venous oxygen tension, with a correlation coefficient of 0.4338 at a confidence level of p less than 0.0001. If the patients were divided into three clinically pertinent groups based on the lowest venous oxygen tension recorded, a strong relationship between venous oxygen tension and lactic acid emerged. If the lowest measurement of venous oxygen tension was greater than 35 mm Hg (group A), the mean rise in lactic acid was only 0.12 microns/ml. If the lowest measurement was between 30 and 34 mm Hg (group B), the mean rise was 0.64 microns/ml. Whereas, if any venous oxygen tension value fell below 30 mm Hg (group C), the mean rise in lactic acid was 2.56 microns/ml. Analysis of variance showed that group C values were significantly different from groups A and B values (p less than 0.0002). A scientific hypothesis relating venous oxygen tension to adequate tissue oxygenation is proposed. Use of venous oxygen tension monitoring with the goal to maintain the level above 35 mm Hg is strongly supported by this study.

Maxillary fibrosarcoma with extracellular immuno-characterization

Maxillary fibrosarcoma of a 31-year-old female is described with special reference to immunofluorescent characterization of the extracellular matrix. Following extractions, endodontic treatment and occlusal adjustment the tumour was operated on. The spindle-shaped tumour cells displayed a herring-bone pattern. The tumour was diagnosed as a fibrosarcoma and graded as poorly differentiated. Immunostaining for the specific type I collagen was positive throughout the tumour matrix, whereas staining for type III collagen was faint and occasional, and did not definitely codistribute with reticulin. Staining for type IV collagen and fibronectin in the tumour matrix was negative.